fix(script): reject a non-object headers, params or cookies in JavaScript

Streaming accepted a chunked body cut at a chunk boundary as complete,
so the limit now comes from the client that reads the body, picked per
requested size. Script requests keep their own default, maxBodySize
accepts sizes like 10MiB, and files sarin downloads for itself are
capped at 64MiB.

.github/workflows/lint.yaml

@@ -13,10 +13,10 @@ jobs:
     name: lint
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v7
-      - uses: actions/setup-go@v6
+      - uses: actions/setup-go@v7
         with:
-          go-version: 1.26.4
+          go-version-file: go.mod
       - name: go fix
         run: |
           go fix ./...
@@ -24,4 +24,4 @@ jobs:
       - name: golangci-lint
         uses: golangci/golangci-lint-action@v9
         with:
-          version: v2.12.2
+          version: v2.14.0

.github/workflows/nix.yaml

@@ -0,0 +1,172 @@
+name: nix
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+    paths:
+      - "go.mod"
+      - "go.sum"
+      - "nix/**"
+      - "flake.nix"
+      - "flake.lock"
+  workflow_call:
+    inputs:
+      ref:
+        description: "Ref to check out. Defaults to the triggering ref."
+        type: string
+        required: false
+
+permissions:
+  contents: read
+
+concurrency:
+  group: nix-${{ github.event_name }}-${{ github.event.pull_request.number || github.ref }}
+  # Keyed on the PR author, which is stable across the fix-up push, so the run
+  # started by that push cannot cancel the run that made it.
+  cancel-in-progress: ${{ github.event_name == 'pull_request' && github.event.pull_request.user.login != 'dependabot[bot]' }}
+
+env:
+  SELF_HOSTED_PR: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.repo.full_name == github.repository }}
+  IS_DEPENDABOT: ${{ github.actor == 'dependabot[bot]' }}
+
+jobs:
+  build:
+    name: build
+    runs-on: ubuntu-latest
+    permissions:
+      # The only write is git push, which authenticates with the PAT that
+      # checkout persists, not with GITHUB_TOKEN.
+      contents: read
+      pull-requests: write
+    steps:
+      - uses: actions/checkout@v7
+        with:
+          # head.sha, not the merge ref: the hash is computed for the tree that
+          # gets pushed, and the run that verifies it must build that same tree.
+          ref: ${{ inputs.ref || github.event.pull_request.head.sha || github.ref }}
+          token: ${{ (env.IS_DEPENDABOT == 'true' && secrets.DEPENDABOT) || secrets.GITHUB_TOKEN }}
+
+      - uses: cachix/install-nix-action@v31
+        with:
+          github_access_token: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: nix build
+        id: build
+        continue-on-error: ${{ env.SELF_HOSTED_PR == 'true' }}
+        run: nix build .#default --no-link --print-build-logs
+
+      - name: Recompute vendorHash
+        id: hash
+        if: steps.build.outcome == 'failure' && env.SELF_HOSTED_PR == 'true'
+        run: |
+          nix run nixpkgs#nix-update -- --flake --version=skip --no-src default
+
+          # An unchanged hash means the build broke for some other reason. Say
+          # nothing and let the job fail on the real error.
+          if git diff --quiet -- nix/package.nix; then
+            echo "stale=false" >> "$GITHUB_OUTPUT"
+            exit 0
+          fi
+
+          echo "stale=true" >> "$GITHUB_OUTPUT"
+          sed -n 's/^[[:space:]]*vendorHash = "\([^"]*\)".*/hash=\1/p' nix/package.nix >> "$GITHUB_OUTPUT"
+
+      - name: Push vendorHash fix
+        if: steps.hash.outputs.stale == 'true' && env.IS_DEPENDABOT == 'true'
+        env:
+          HEAD_REF: ${{ github.head_ref }}
+          PUSH_TOKEN: ${{ secrets.DEPENDABOT }}
+        run: |
+          if [ -z "$PUSH_TOKEN" ]; then
+            echo "::error::the DEPENDABOT push token is missing from the Dependabot secret store"
+            exit 1
+          fi
+          git config user.name "github-actions[bot]"
+          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
+          git add nix/package.nix
+          git commit -m "fix(nix): update vendorHash [dependabot skip]"
+          git push origin "HEAD:refs/heads/$HEAD_REF"
+          echo "::notice::vendorHash updated and pushed; the run on the new commit decides this PR"
+
+      - name: Comment stale vendorHash
+        if: steps.hash.outputs.stale == 'true' && env.IS_DEPENDABOT != 'true'
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          PR: ${{ github.event.pull_request.number }}
+          HASH: ${{ steps.hash.outputs.hash }}
+        run: |
+          marker='<!-- vendorhash-bot -->'
+          body=$(cat <<EOF
+          $marker
+          ### \`nix/package.nix\` vendorHash is stale
+
+          This branch changes the Go dependencies, so the vendor derivation no longer matches the pinned hash and \`nix build\` fails.
+
+          \`\`\`nix
+          vendorHash = "$HASH";
+          \`\`\`
+
+          Run \`task nix-hash\` locally and commit the result, or paste the hash above.
+          EOF
+          )
+
+          # Keep one sticky comment instead of a new one on every push. Without
+          # the explicit check a failed lookup reads as "no comment yet" and
+          # posts a duplicate; piping into head would hide the exit status.
+          if ! matches=$(gh api --paginate "repos/$GITHUB_REPOSITORY/issues/$PR/comments?per_page=100" \
+                           --jq ".[] | select(.user.login == \"github-actions[bot]\" and ((.body // \"\") | contains(\"$marker\"))) | .id"); then
+            echo "::error::could not list the pull request comments"
+            exit 1
+          fi
+          id=$(printf '%s\n' "$matches" | head -n 1)
+          if [ -n "$id" ]; then
+            gh api -X PATCH "repos/$GITHUB_REPOSITORY/issues/comments/$id" -f body="$body" >/dev/null
+          else
+            gh pr comment "$PR" --body "$body"
+          fi
+
+      # Once the hash is fixed the build passes and the step above stops running,
+      # so without this the comment keeps claiming the branch is broken under a
+      # green check.
+      - name: Resolve stale vendorHash comment
+        # Gated on the hash rather than the build: a later push can fix the hash
+        # while the build still fails for an unrelated reason, and the comment
+        # must stop blaming the vendor derivation either way. Skipped when the
+        # recompute itself errored, since then we do not know.
+        if: ${{ !cancelled() && env.SELF_HOSTED_PR == 'true' && steps.hash.outputs.stale != 'true' && steps.hash.outcome != 'failure' }}
+        continue-on-error: true
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          PR: ${{ github.event.pull_request.number }}
+          BUILD: ${{ steps.build.outcome }}
+        run: |
+          marker='<!-- vendorhash-bot -->'
+          if ! matches=$(gh api --paginate "repos/$GITHUB_REPOSITORY/issues/$PR/comments?per_page=100" \
+                           --jq ".[] | select(.user.login == \"github-actions[bot]\" and ((.body // \"\") | contains(\"$marker\"))) | .id"); then
+            echo "::error::could not list the pull request comments"
+            exit 1
+          fi
+          id=$(printf '%s\n' "$matches" | head -n 1)
+          [ -n "$id" ] || exit 0
+
+          if [ "$BUILD" = "success" ]; then
+            detail='`nix build` passes on this branch.'
+          else
+            detail='The build is failing for another reason; see the workflow log.'
+          fi
+          body=$(cat <<EOF
+          $marker
+          ### \`nix/package.nix\` vendorHash is up to date
+
+          $detail
+          EOF
+          )
+          gh api -X PATCH "repos/$GITHUB_REPOSITORY/issues/comments/$id" -f body="$body" >/dev/null
+
+      - name: Report build failure
+        if: ${{ !cancelled() && steps.build.outcome == 'failure' && !(env.IS_DEPENDABOT == 'true' && steps.hash.outputs.stale == 'true') }}
+        run: |
+          echo "::error file=nix/package.nix::nix build failed; see the log above"
+          exit 1

.github/workflows/release.yaml

@@ -2,50 +2,101 @@ name: Build and Release
 
 on:
   release:
-    types: [created]
+    types: [published]
-  workflow_dispatch:
-    inputs:
-      tag:
-        description: "Release tag (e.g., v1.0.0)"
-        required: true
-      build_binaries:
-        description: "Build and upload binaries"
-        type: boolean
-        default: true
-      build_docker:
-        description: "Build and push Docker image"
-        type: boolean
-        default: true
 
 permissions:
   contents: write
 
 jobs:
+  nix:
+    name: Verify Nix package
+    uses: ./.github/workflows/nix.yaml
+    permissions:
+      contents: read
+      pull-requests: write
+    with:
+      ref: ${{ github.ref }}
+
+  # Gate: the tag must come from main, agree with the pre-release flag, and match
+  # the hand-bumped version in nix/package.nix.
+  version:
+    name: Verify release
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+    env:
+      TAG: ${{ github.ref_name }}
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v7
+        with:
+          ref: ${{ github.ref }}
+          # Full history so the tag can be located on main's first-parent line.
+          fetch-depth: 0
+
+      - name: Check the tag is on main
+        run: |
+          git fetch --no-tags origin "+refs/heads/main:refs/remotes/origin/main"
+          git rev-list --first-parent refs/remotes/origin/main > "$RUNNER_TEMP/first-parent.txt"
+          if ! grep -qxF "$GITHUB_SHA" "$RUNNER_TEMP/first-parent.txt"; then
+            echo "::error::$TAG ($GITHUB_SHA) is not on main; releases must be cut from main"
+            exit 1
+          fi
+
+      - name: Check the tag matches the pre-release flag
+        env:
+          PRERELEASE: ${{ github.event.release.prerelease }}
+        run: |
+          # The flag comes from the checkbox, not the tag name, so without this a
+          # tag like v1.5.0-rc1 published as stable would move :latest.
+          case "$TAG" in
+            *-*)
+              if [ "$PRERELEASE" != "true" ]; then
+                echo "::error::tag '$TAG' carries a pre-release suffix but the release is not marked as a pre-release"
+                exit 1
+              fi
+              ;;
+          esac
+
+      - name: Check nix/package.nix matches the release tag
+        run: |
+          expected="${TAG#v}"
+          expected="${expected%%-*}"
+          actual="$(sed -n 's/^[[:space:]]*version = "\([^"]*\)".*/\1/p' nix/package.nix | head -1)"
+          if [ -z "$actual" ]; then
+            echo "::error file=nix/package.nix::could not read the version string"
+            exit 1
+          fi
+          if [ "$actual" != "$expected" ]; then
+            echo "::error file=nix/package.nix::version is '$actual' but the release tag is '$TAG' (expected '$expected')"
+            exit 1
+          fi
+          echo "nix/package.nix version '$actual' matches tag '$TAG'"
+
   build:
     name: Build binaries
+    needs: [nix, version]
     runs-on: ubuntu-latest
 
     steps:
       - name: Checkout code
-        uses: actions/checkout@v6
+        uses: actions/checkout@v7
         with:
-          ref: ${{ inputs.tag || github.ref }}
+          ref: ${{ github.ref }}
 
       - name: Set build metadata
         run: |
           echo "VERSION=$(git describe --tags --always)" >> $GITHUB_ENV
           echo "GIT_COMMIT=$(git rev-parse HEAD)" >> $GITHUB_ENV
-          echo "GO_VERSION=1.26.4" >> $GITHUB_ENV
+          echo "GO_VERSION=$(sed -n 's/^go //p' go.mod)" >> $GITHUB_ENV
 
       - name: Set up Go
-        if: github.event_name == 'release' || inputs.build_binaries
+        uses: actions/setup-go@v7
-        uses: actions/setup-go@v6
         with:
-          go-version: ${{ env.GO_VERSION }}
+          go-version-file: go.mod
           cache: true
 
       - name: Build binaries
-        if: github.event_name == 'release' || inputs.build_binaries
         run: |
           LDFLAGS="-X 'go.aykhans.me/sarin/internal/version.Version=${{ env.VERSION }}' \
                    -X 'go.aykhans.me/sarin/internal/version.GitCommit=${{ env.GIT_COMMIT }}' \
@@ -63,29 +114,24 @@ jobs:
           CGO_ENABLED=0 GOOS=windows GOARCH=arm64 go build -ldflags "$LDFLAGS" -o ./sarin-windows-arm64.exe ./cmd/cli/main.go
 
       - name: Upload Release Assets
-        if: github.event_name == 'release' || inputs.build_binaries
         uses: softprops/action-gh-release@v3
         with:
-          tag_name: ${{ inputs.tag || github.ref_name }}
+          tag_name: ${{ github.ref_name }}
           files: ./sarin-*
 
       - name: Set up QEMU
-        if: github.event_name == 'release' || inputs.build_docker
         uses: docker/setup-qemu-action@v4
 
       - name: Set up Docker Buildx
-        if: github.event_name == 'release' || inputs.build_docker
         uses: docker/setup-buildx-action@v4
 
       - name: Login to Docker Hub
-        if: github.event_name == 'release' || inputs.build_docker
         uses: docker/login-action@v4
         with:
           username: ${{ secrets.DOCKERHUB_USERNAME }}
           password: ${{ secrets.DOCKERHUB_TOKEN }}
 
       - name: Build and push Docker image
-        if: github.event_name == 'release' || inputs.build_docker
         uses: docker/build-push-action@v7
         with:
           context: .
@@ -95,6 +141,56 @@ jobs:
             VERSION=${{ env.VERSION }}
             GIT_COMMIT=${{ env.GIT_COMMIT }}
             GO_VERSION=${{ env.GO_VERSION }}
+          # A pre-release must not take over the tag people get by default.
           tags: |
             ${{ secrets.DOCKERHUB_USERNAME }}/sarin:${{ env.VERSION }}
-            ${{ secrets.DOCKERHUB_USERNAME }}/sarin:latest
+            ${{ !github.event.release.prerelease && format('{0}/sarin:latest', secrets.DOCKERHUB_USERNAME) || '' }}
+
+  # Moving pointer at the newest stable release, so flake users can follow
+  # releases instead of main. Fast-forward only.
+  release-branch:
+    name: Advance release branch
+    needs: build
+    if: ${{ !github.event.release.prerelease }}
+    runs-on: ubuntu-latest
+    permissions:
+      contents: write
+    # Serialize: concurrent releases would otherwise race the push.
+    concurrency:
+      group: release-branch
+      cancel-in-progress: false
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v7
+        with:
+          # The checks below compare against $GITHUB_SHA; check out exactly that.
+          ref: ${{ github.sha }}
+          fetch-depth: 0
+
+      - name: Point release at the tag
+        env:
+          TAG: ${{ github.ref_name }}
+        run: |
+          # Refresh: checkout fetched this, but as of a few seconds ago.
+          git fetch --no-tags origin "+refs/heads/release:refs/remotes/origin/release" || true
+
+          if git rev-parse --verify --quiet refs/remotes/origin/release >/dev/null; then
+            # At or behind the pointer: a re-run of this or an older release.
+            if git merge-base --is-ancestor "$GITHUB_SHA" refs/remotes/origin/release; then
+              if [ "$(git rev-parse refs/remotes/origin/release)" = "$GITHUB_SHA" ]; then
+                echo "::notice::release is already at $TAG"
+              else
+                echo "::warning::release is ahead of $TAG; leaving it alone"
+              fi
+              exit 0
+            fi
+            # The version job put this commit on main, so a pointer that is neither
+            # behind nor ahead is off main history and can never fast-forward again.
+            if ! git merge-base --is-ancestor refs/remotes/origin/release "$GITHUB_SHA"; then
+              echo "::error::release ($(git rev-parse --short refs/remotes/origin/release)) has diverged from main and can no longer fast-forward to $TAG; reset it by hand"
+              exit 1
+            fi
+          fi
+
+          git push origin "$GITHUB_SHA:refs/heads/release"
+          echo "::notice::release branch now points at $TAG"

.gitignore

@@ -1 +1,5 @@
 bin/*
+
+# Nix build artifacts
+result
+result-*

.golangci.yaml

@@ -1,7 +1,7 @@
 version: "2"
 
 run:
-  go: "1.26"
+  go: "1.27"
   concurrency: 12
 
 linters:
@@ -81,6 +81,11 @@ linters:
           - staticcheck
         text: "SA5011"
 
+      - linters:
+          - errcheck
+          - gosec
+        source: "lipgloss\\.Println\\("
+
 formatters:
   enable:
     - gofmt

Dockerfile

@@ -1,4 +1,4 @@
-ARG GO_VERSION=1.26.4
+ARG GO_VERSION=1.27.1
 
 FROM docker.io/library/golang:${GO_VERSION}-alpine AS builder
 

README.md

@@ -3,7 +3,9 @@
 ## Sarin is a high-performance HTTP load testing tool built with Go and fasthttp.
 
 [![Go Reference](https://pkg.go.dev/badge/go.aykhans.me/sarin.svg)](https://pkg.go.dev/go.aykhans.me/sarin)
-[![Go Report Card](https://goreportcard.com/badge/go.aykhans.me/sarin)](https://goreportcard.com/report/go.aykhans.me/sarin)
+[![Docker Pulls](https://img.shields.io/docker/pulls/aykhans/sarin)](https://hub.docker.com/r/aykhans/sarin)
+[![Downloads](https://img.shields.io/github/downloads/aykhans/sarin/total?cacheSeconds=3600)](https://github.com/aykhans/sarin/releases)
+[![Lint](https://img.shields.io/github/actions/workflow/status/aykhans/sarin/lint.yaml?branch=main&label=lint)](https://github.com/aykhans/sarin/actions/workflows/lint.yaml)
 [![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](https://opensource.org/licenses/MIT)
 
 </div>
@@ -24,20 +26,19 @@ Sarin is designed for efficient HTTP load testing with minimal resource consumpt
 
 | ✅ Supported                                               | ❌ Not Supported                |
 | ---------------------------------------------------------- | ------------------------------- |
-| High-performance with low memory footprint                 | Detailed response body analysis |
+| High-performance with low memory footprint                 | Web UI or complex TUI           |
-| Long-running duration/count based tests                    | Extensive response statistics   |
+| Dynamic requests via 370+ template functions               | Detailed response body analysis |
-| Dynamic requests via 340+ template functions               | Web UI or complex TUI           |
 | Request scripting with Lua and JavaScript                  | Distributed load testing        |
 | Multiple proxy protocols<br>(HTTP, HTTPS, SOCKS5, SOCKS5H) | HTTP/2, HTTP/3, WebSocket, gRPC |
 | Captcha solving<br>(2Captcha, Anti-Captcha, CapSolver)     | Plugins / extensions ecosystem  |
-| Flexible config (CLI, ENV, YAML)                           |                                 |
 
 ## Installation
 
-### Docker (Recommended)
+<details open>
+<summary><b>Docker</b></summary>
 
 ```sh
-docker pull aykhans/sarin:latest
+docker run --rm -it aykhans/sarin:latest --version
 ```
 
 With a local config file:
@@ -52,13 +53,50 @@ With a remote config file:
 docker run --rm -it aykhans/sarin -f https://example.com/config.yaml
 ```
 
-### Pre-built Binaries
+</details>
+
+<details>
+<summary><b>Nix</b></summary>
+
+Run directly without installing (requires flakes enabled):
+
+```sh
+nix run github:aykhans/sarin/release -- -U http://example.com -r 100 -c 10
+```
+
+Install into your profile:
+
+```sh
+nix profile add github:aykhans/sarin/release
+```
+
+Or add it to your own flake via the overlay:
+
+```nix
+{
+  inputs.sarin.url = "github:aykhans/sarin/release";
+
+  # In your outputs, apply the overlay to nixpkgs:
+  # nixpkgs.overlays = [ inputs.sarin.overlays.default ];
+  # then reference pkgs.sarin
+}
+```
+
+The `release` branch tracks the newest stable release cut from `main`, so `nix flake update` moves between releases rather than following every commit; pre-releases are excluded. Pin an exact release with `github:aykhans/sarin/v1.4.2`, or track development with `github:aykhans/sarin` (the `main` branch).
+
+</details>
+
+<details>
+<summary><b>Pre-built Binaries</b></summary>
 
 Download the latest binaries from the [releases](https://github.com/aykhans/sarin/releases) page.
 
-### Building from Source
+</details>
 
-Requires [Go 1.26+](https://golang.org/dl/).
+<details>
+<summary><b>Building from Source</b></summary>
+
+Requires the [Go version declared in `go.mod`](go.mod).
 
 ```sh
 git clone https://github.com/aykhans/sarin.git && cd sarin
@@ -72,6 +110,8 @@ CGO_ENABLED=0 go build \
     -o sarin ./cmd/cli/main.go
 ```
 
+</details>
+
 ## Quick Start
 
 Send 10,000 GET requests with 50 concurrent connections and a random User-Agent for each request:
@@ -106,7 +146,7 @@ For detailed documentation on all configuration options (URL, method, timeout, c
 
 ## Templating
 
-Sarin supports Go templates in URL paths, methods, bodies, headers, params, cookies, and values. Use the 340+ built-in functions to generate dynamic data for each request.
+Sarin supports Go templates in URL paths, methods, bodies, headers, params, cookies, and values. Use the 370+ built-in functions to generate dynamic data for each request.
 
 **Example:**
 

Taskfile.yaml

@@ -3,7 +3,9 @@ version: "3"
 
 vars:
   BIN_DIR: ./bin
-  GOLANGCI_LINT_VERSION: v2.12.2
+  GO_VERSION:
+    sh: sed -n 's/^go //p' go.mod
+  GOLANGCI_LINT_VERSION: v2.14.0
   GOLANGCI: "{{.BIN_DIR}}/golangci-lint-{{.GOLANGCI_LINT_VERSION}}"
 
 tasks:
@@ -39,6 +41,11 @@ tasks:
     cmds:
       - "{{.GOLANGCI}} run"
 
+  nix-hash:
+    desc: Recompute nix/package.nix vendorHash after a dependency change.
+    cmds:
+      - nix run nixpkgs#nix-update -- --flake --version=skip --no-src default
+
   test:
     desc: Run Go tests.
     cmds:
@@ -82,7 +89,6 @@ tasks:
     vars:
       IMAGE_NAME: '{{.IMAGE_NAME | default "sarin"}}'
       TAG: '{{.TAG | default "latest"}}'
-      GO_VERSION: '{{.GO_VERSION | default ""}}'
       VERSION:
         sh: git describe --tags --always
       GIT_COMMIT:
@@ -90,7 +96,7 @@ tasks:
     cmds:
       - >-
         docker build
-        {{if .GO_VERSION}}--build-arg GO_VERSION={{.GO_VERSION}}{{end}}
+        --build-arg GO_VERSION={{.GO_VERSION}}
         --build-arg VERSION={{.VERSION}}
         --build-arg GIT_COMMIT={{.GIT_COMMIT}}
         -t {{.IMAGE_NAME}}:{{.TAG}}

cmd/cli/main.go

@@ -7,6 +7,7 @@ import (
 	"os/signal"
 	"syscall"
 
+	"charm.land/lipgloss/v2"
 	"go.aykhans.me/sarin/internal/config"
 	"go.aykhans.me/sarin/internal/sarin"
 	"go.aykhans.me/sarin/internal/types"
@@ -32,13 +33,13 @@ func main() {
 		utilsErr.OnType(func(err types.FieldValidationErrors) error {
 			for _, fieldErr := range err.Errors {
 				if fieldErr.Value == "" {
-					fmt.Fprintln(os.Stderr,
+					fmt.Fprint(os.Stderr, lipgloss.Sprintln(
 						config.StyleYellow.Render(fmt.Sprintf("[VALIDATION] Field '%s': ", fieldErr.Field))+fieldErr.Err.Error(),
-					)
+					))
 				} else {
-					fmt.Fprintln(os.Stderr,
+					fmt.Fprint(os.Stderr, lipgloss.Sprintln(
 						config.StyleYellow.Render(fmt.Sprintf("[VALIDATION] Field '%s' (%s): ", fieldErr.Field, fieldErr.Value))+fieldErr.Err.Error(),
-					)
+					))
 				}
 			}
 			os.Exit(1)
@@ -50,31 +51,32 @@ func main() {
 		ctx,
 		combinedConfig.Methods, combinedConfig.URL, *combinedConfig.Timeout,
 		*combinedConfig.Concurrency, combinedConfig.Requests, combinedConfig.Duration,
-		*combinedConfig.Quiet, *combinedConfig.Insecure, combinedConfig.Params, combinedConfig.Headers,
+		*combinedConfig.Progress == config.ConfigProgressTypeBar, *combinedConfig.Insecure, *combinedConfig.MaxResponseBody,
+		combinedConfig.Params, combinedConfig.Headers,
 		combinedConfig.Cookies, combinedConfig.Bodies, combinedConfig.Proxies, combinedConfig.Values,
 		*combinedConfig.Output != config.ConfigOutputTypeNone,
-		*combinedConfig.DryRun,
+		*combinedConfig.DryRun, *combinedConfig.LogLevel, *combinedConfig.LogFile,
 		combinedConfig.Lua, combinedConfig.Js,
 	)
 	_ = utilsErr.MustHandle(err,
 		utilsErr.OnType(func(err types.ProxyDialError) error {
-			fmt.Fprintln(os.Stderr, config.StyleRed.Render("[PROXY] ")+err.Error())
+			fmt.Fprint(os.Stderr, lipgloss.Sprintln(config.StyleRed.Render("[PROXY] ")+err.Error()))
 			os.Exit(1)
 			return nil
 		}),
 		utilsErr.OnSentinel(types.ErrScriptEmpty, func(err error) error {
-			fmt.Fprintln(os.Stderr, config.StyleRed.Render("[SCRIPT] ")+err.Error())
+			fmt.Fprint(os.Stderr, lipgloss.Sprintln(config.StyleRed.Render("[SCRIPT] ")+err.Error()))
 			os.Exit(1)
 			return nil
 		}),
 		utilsErr.OnType(func(err types.ScriptLoadError) error {
-			fmt.Fprintln(os.Stderr, config.StyleRed.Render("[SCRIPT] ")+err.Error())
+			fmt.Fprint(os.Stderr, lipgloss.Sprintln(config.StyleRed.Render("[SCRIPT] ")+err.Error()))
 			os.Exit(1)
 			return nil
 		}),
 	)
 
-	srn.Start(ctx, stopCtrl)
+	srn.Start(stopCtrl)
 
 	switch *combinedConfig.Output {
 	case config.ConfigOutputTypeNone:

docs/configuration.md

@@ -14,30 +14,33 @@ Use `-s` or `--show-config` to see the final merged configuration before sending
 
 > **Note:** For CLI flags with `string / []string` type, the flag can be used once with a single value or multiple times to provide multiple values.
 
-| Name                        | YAML                                | CLI                                          | ENV                              | Default | Description                  |
+| Name                                    | YAML                                | CLI                                          | ENV                                 | Default | Description                   |
-| --------------------------- | ----------------------------------- | -------------------------------------------- | -------------------------------- | ------- | ---------------------------- |
+| --------------------------------------- | ----------------------------------- | -------------------------------------------- | ----------------------------------- | ------- | ----------------------------- |
-| [Help](#help)               | -                                   | `-help` / `-h`                               | -                                | -       | Show help message            |
+| [Help](#help)                           | -                                   | `-help` / `-h`                               | -                                   | -       | Show help message             |
-| [Version](#version)         | -                                   | `-version` / `-v`                            | -                                | -       | Show version and build info  |
+| [Version](#version)                     | -                                   | `-version` / `-v`                            | -                                   | -       | Show version and build info   |
-| [Show Config](#show-config) | `showConfig`<br>(boolean)           | `-show-config` / `-s`<br>(boolean)           | `SARIN_SHOW_CONFIG`<br>(boolean) | `false` | Show merged configuration    |
+| [Show Config](#show-config)             | `showConfig`<br>(boolean)           | `-show-config` / `-s`<br>(boolean)           | `SARIN_SHOW_CONFIG`<br>(boolean)    | `false` | Show merged configuration     |
-| [Config File](#config-file) | `configFile`<br>(string / []string) | `-config-file` / `-f`<br>(string / []string) | `SARIN_CONFIG_FILE`<br>(string)  | -       | Path to config file(s)       |
+| [Config File](#config-file)             | `configFile`<br>(string / []string) | `-config-file` / `-f`<br>(string / []string) | `SARIN_CONFIG_FILE`<br>(string)     | -       | Path to config file(s)        |
-| [URL](#url)                 | `url`<br>(string)                   | `-url` / `-U`<br>(string)                    | `SARIN_URL`<br>(string)          | -       | Target URL (HTTP/HTTPS)      |
+| [URL](#url)                             | `url`<br>(string)                   | `-url` / `-U`<br>(string)                    | `SARIN_URL`<br>(string)             | -       | Target URL (HTTP/HTTPS)       |
-| [Method](#method)           | `method`<br>(string / []string)     | `-method` / `-M`<br>(string / []string)      | `SARIN_METHOD`<br>(string)       | `GET`   | HTTP method(s)               |
+| [Method](#method)                       | `method`<br>(string / []string)     | `-method` / `-M`<br>(string / []string)      | `SARIN_METHOD`<br>(string)          | `GET`   | HTTP method(s)                |
-| [Timeout](#timeout)         | `timeout`<br>(duration)             | `-timeout` / `-T`<br>(duration)              | `SARIN_TIMEOUT`<br>(duration)    | `10s`   | Request timeout              |
+| [Timeout](#timeout)                     | `timeout`<br>(duration)             | `-timeout` / `-T`<br>(duration)              | `SARIN_TIMEOUT`<br>(duration)       | `10s`   | Request timeout               |
-| [Concurrency](#concurrency) | `concurrency`<br>(number)           | `-concurrency` / `-c`<br>(number)            | `SARIN_CONCURRENCY`<br>(number)  | `1`     | Number of concurrent workers |
+| [Max Response Body](#max-response-body) | `maxResponseBody`<br>(size)         | `-max-response-body` / `-S`<br>(size)        | `SARIN_MAX_RESPONSE_BODY`<br>(size) | `10MiB` | Largest response body to read |
-| [Requests](#requests)       | `requests`<br>(number)              | `-requests` / `-r`<br>(number)               | `SARIN_REQUESTS`<br>(number)     | -       | Total requests to send       |
+| [Concurrency](#concurrency)             | `concurrency`<br>(number)           | `-concurrency` / `-c`<br>(number)            | `SARIN_CONCURRENCY`<br>(number)     | `1`     | Number of concurrent workers  |
-| [Duration](#duration)       | `duration`<br>(duration)            | `-duration` / `-d`<br>(duration)             | `SARIN_DURATION`<br>(duration)   | -       | Test duration                |
+| [Requests](#requests)                   | `requests`<br>(number)              | `-requests` / `-r`<br>(number)               | `SARIN_REQUESTS`<br>(number)        | -       | Total requests to send        |
-| [Quiet](#quiet)             | `quiet`<br>(boolean)                | `-quiet` / `-q`<br>(boolean)                 | `SARIN_QUIET`<br>(boolean)       | `false` | Hide progress bar and logs   |
+| [Duration](#duration)                   | `duration`<br>(duration)            | `-duration` / `-d`<br>(duration)             | `SARIN_DURATION`<br>(duration)      | -       | Test duration                 |
-| [Output](#output)           | `output`<br>(string)                | `-output` / `-o`<br>(string)                 | `SARIN_OUTPUT`<br>(string)       | `table` | Output format for stats      |
+| [Log Level](#log-level)                 | `logLevel`<br>(string)              | `-log-level` / `-l`<br>(string)              | `SARIN_LOG_LEVEL`<br>(string)       | `error` | Runtime log levels to emit    |
-| [Dry Run](#dry-run)         | `dryRun`<br>(boolean)               | `-dry-run` / `-z`<br>(boolean)               | `SARIN_DRY_RUN`<br>(boolean)     | `false` | Generate without sending     |
+| [Log File](#log-file)                   | `logFile`<br>(string)               | `-log-file` / `-w`<br>(string)               | `SARIN_LOG_FILE`<br>(string)        | -       | Write runtime logs to a file  |
-| [Insecure](#insecure)       | `insecure`<br>(boolean)             | `-insecure` / `-I`<br>(boolean)              | `SARIN_INSECURE`<br>(boolean)    | `false` | Skip TLS verification        |
+| [Progress](#progress)                   | `progress`<br>(string)              | `-progress` / `-p`<br>(string)               | `SARIN_PROGRESS`<br>(string)        | `bar`   | Progress display (bar/none)   |
-| [Body](#body)               | `body`<br>(string / []string)       | `-body` / `-B`<br>(string / []string)        | `SARIN_BODY`<br>(string)         | -       | Request body                 |
+| [Output](#output)                       | `output`<br>(string)                | `-output` / `-o`<br>(string)                 | `SARIN_OUTPUT`<br>(string)          | `table` | Output format for stats       |
-| [Params](#params)           | `params`<br>(object)                | `-param` / `-P`<br>(string / []string)       | `SARIN_PARAM`<br>(string)        | -       | URL query parameters         |
+| [Dry Run](#dry-run)                     | `dryRun`<br>(boolean)               | `-dry-run` / `-z`<br>(boolean)               | `SARIN_DRY_RUN`<br>(boolean)        | `false` | Generate without sending      |
-| [Headers](#headers)         | `headers`<br>(object)               | `-header` / `-H`<br>(string / []string)      | `SARIN_HEADER`<br>(string)       | -       | HTTP headers                 |
+| [Insecure](#insecure)                   | `insecure`<br>(boolean)             | `-insecure` / `-I`<br>(boolean)              | `SARIN_INSECURE`<br>(boolean)       | `false` | Skip TLS verification         |
-| [Cookies](#cookies)         | `cookies`<br>(object)               | `-cookie` / `-C`<br>(string / []string)      | `SARIN_COOKIE`<br>(string)       | -       | HTTP cookies                 |
+| [Body](#body)                           | `body`<br>(string / []string)       | `-body` / `-B`<br>(string / []string)        | `SARIN_BODY`<br>(string)            | -       | Request body                  |
-| [Proxy](#proxy)             | `proxy`<br>(string / []string)      | `-proxy` / `-X`<br>(string / []string)       | `SARIN_PROXY`<br>(string)        | -       | Proxy URL(s)                 |
+| [Params](#params)                       | `params`<br>(object)                | `-param` / `-P`<br>(string / []string)       | `SARIN_PARAM`<br>(string)           | -       | URL query parameters          |
-| [Values](#values)           | `values`<br>(string / []string)     | `-values` / `-V`<br>(string / []string)      | `SARIN_VALUES`<br>(string)       | -       | Template values (key=value)  |
+| [Headers](#headers)                     | `headers`<br>(object)               | `-header` / `-H`<br>(string / []string)      | `SARIN_HEADER`<br>(string)          | -       | HTTP headers                  |
-| [Lua](#lua)                 | `lua`<br>(string / []string)        | `-lua`<br>(string / []string)                | `SARIN_LUA`<br>(string)          | -       | Lua script(s)                |
+| [Cookies](#cookies)                     | `cookies`<br>(object)               | `-cookie` / `-C`<br>(string / []string)      | `SARIN_COOKIE`<br>(string)          | -       | HTTP cookies                  |
-| [Js](#js)                   | `js`<br>(string / []string)         | `-js`<br>(string / []string)                 | `SARIN_JS`<br>(string)           | -       | JavaScript script(s)         |
+| [Proxy](#proxy)                         | `proxy`<br>(string / []string)      | `-proxy` / `-X`<br>(string / []string)       | `SARIN_PROXY`<br>(string)           | -       | Proxy URL(s)                  |
+| [Values](#values)                       | `values`<br>(string / []string)     | `-values` / `-V`<br>(string / []string)      | `SARIN_VALUES`<br>(string)          | -       | Template values (key=value)   |
+| [Lua](#lua)                             | `lua`<br>(string / []string)        | `-lua`<br>(string / []string)                | `SARIN_LUA`<br>(string)             | -       | Lua script(s)                 |
+| [Js](#js)                               | `js`<br>(string / []string)         | `-js`<br>(string / []string)                 | `SARIN_JS`<br>(string)              | -       | JavaScript script(s)          |
 
 ---
 
@@ -131,7 +134,7 @@ sarin -U "http://example.com/users/{{ fakeit_UUID }}" -r 1000 -c 10
 
 ## Method
 
-HTTP method(s). If multiple values are provided, Sarin cycles through them in order, starting from a random index for each request. Supports [templating](templating.md).
+HTTP method(s). Defaults to `GET`. If multiple values are provided, Sarin starts at a random index and cycles through them in order. Once the cycle completes, it picks a new random starting point. Supports [templating](templating.md).
 
 **YAML example:**
 
@@ -141,9 +144,9 @@ method: GET
 # OR
 
 method:
-  - GET
+    - GET
-  - POST
+    - POST
-  - PUT
+    - PUT
 ```
 
 **CLI example:**
@@ -160,15 +163,27 @@ SARIN_METHOD=GET
 
 ## Timeout
 
-Request timeout. Must be greater than 0.
+Request timeout. Must be greater than 0. Defaults to `10s`.
 
 Valid time units: `ns`, `us` (or `µs`), `ms`, `s`, `m`, `h`
 
 **Examples:** `5s`, `300ms`, `1m20s`
 
+## Max Response Body
+
+Largest response body sarin reads. Defaults to `10MiB`, and `0` removes the limit.
+
+The value is a whole number of bytes, with or without a unit: `B`, `KB`, `MB`, `GB`, `TB` are powers of 1000, `KiB`, `MiB`, `GiB`, `TiB` are powers of 1024. Case is ignored and a space before the unit is allowed. The largest accepted value is `1GiB`, because one response can take a few times the limit in memory.
+
+**Examples:** `1048576`, `10MiB`, `2MB`, `512KiB`
+
+A server can declare a `Content-Length` far larger than it sends, and the body is allocated from that declared length, so without a limit a single response can exhaust memory. A response above the limit fails with `response body exceeds the body limit` and is counted like any other error.
+
+The limit applies per response in flight, and a declared Content-Length is allocated up to it, so the worst case is a few times the limit times the concurrency. It covers the requests scripts make as well.
+
 ## Concurrency
 
-Number of concurrent workers. Must be between 1 and 100,000,000.
+Number of concurrent workers. Must be between 1 and 100,000,000. Defaults to `1`.
 
 ## Requests
 
@@ -182,15 +197,34 @@ Valid time units: `ns`, `us` (or `µs`), `ms`, `s`, `m`, `h`
 
 **Examples:** `1m30s`, `25s`, `1h`
 
-## Quiet
+## Log Level
 
-Hide the progress bar and runtime logs.
+Runtime log levels to emit, comma-separated. Valid levels: `info`, `error`. Defaults to `error`.
+
+- `error`: errors that occur while generating or sending a request
+- `info`: every completed response
+
+Leave empty to disable logging entirely.
+
+**Examples:** `error` (only errors), `info` (only responses), `info,error` (both)
+
+## Log File
+
+Write runtime logs to this file instead of the terminal or stderr. The parent directory must exist.
+
+```sh
+sarin -U http://example.com -r 1000 --log-file ./run.log
+```
+
+## Progress
+
+Progress display. Valid values: `bar` (default), `none`. Use `none` to hide the progress bar.
 
 ## Output
 
 Output format for response statistics.
 
-Valid formats: `table`, `json`, `yaml`, `none`
+Valid formats: `table` (default), `json`, `yaml`, `none`
 
 Using `none` disables output and reduces memory usage since response statistics are not stored.
 
@@ -204,7 +238,7 @@ Skip TLS certificate verification.
 
 ## Body
 
-Request body. If multiple values are provided, Sarin cycles through them in order, starting from a random index for each request. Supports [templating](templating.md).
+Request body. If multiple values are provided, Sarin starts at a random index and cycles through them in order. Once the cycle completes, it picks a new random starting point. Supports [templating](templating.md).
 
 **YAML example:**
 
@@ -214,9 +248,9 @@ body: '{"product": "car"}'
 # OR
 
 body:
-  - '{"product": "car"}'
+    - '{"product": "car"}'
-  - '{"product": "phone"}'
+    - '{"product": "phone"}'
-  - '{"product": "watch"}'
+    - '{"product": "watch"}'
 ```
 
 **CLI example:**
@@ -241,19 +275,19 @@ When the same key appears as **separate entries** (in CLI or config file), all v
 
 ```yaml
 params:
-  key1: value1
+    key1: value1
-  key2: [value2, value3]  # cycles between value2 and value3
+    key2: [value2, value3] # cycles between value2 and value3
 
 # OR
 
 params:
-  - key1: value1
+    - key1: value1
-  - key2: [value2, value3]  # cycles between value2 and value3
+    - key2: [value2, value3] # cycles between value2 and value3
 
 # To send both values in every request, use separate entries:
 params:
-  - key2: value2
+    - key2: value2
-  - key2: value3  # both sent in every request
+    - key2: value3 # both sent in every request
 ```
 
 **CLI example:**
@@ -278,19 +312,19 @@ When the same key appears as **separate entries** (in CLI or config file), all v
 
 ```yaml
 headers:
-  key1: value1
+    key1: value1
-  key2: [value2, value3]  # cycles between value2 and value3
+    key2: [value2, value3] # cycles between value2 and value3
 
 # OR
 
 headers:
-  - key1: value1
+    - key1: value1
-  - key2: [value2, value3]  # cycles between value2 and value3
+    - key2: [value2, value3] # cycles between value2 and value3
 
 # To send both values in every request, use separate entries:
 headers:
-  - key2: value2
+    - key2: value2
-  - key2: value3  # both sent in every request
+    - key2: value3 # both sent in every request
 ```
 
 **CLI example:**
@@ -315,19 +349,19 @@ When the same key appears as **separate entries** (in CLI or config file), all v
 
 ```yaml
 cookies:
-  key1: value1
+    key1: value1
-  key2: [value2, value3]  # cycles between value2 and value3
+    key2: [value2, value3] # cycles between value2 and value3
 
 # OR
 
 cookies:
-  - key1: value1
+    - key1: value1
-  - key2: [value2, value3]  # cycles between value2 and value3
+    - key2: [value2, value3] # cycles between value2 and value3
 
 # To send both values in every request, use separate entries:
 cookies:
-  - key2: value2
+    - key2: value2
-  - key2: value3  # both sent in every request
+    - key2: value3 # both sent in every request
 ```
 
 **CLI example:**
@@ -344,7 +378,7 @@ SARIN_COOKIE="key1=value1"
 
 ## Proxy
 
-Proxy URL(s). If multiple values are provided, Sarin cycles through them in order, starting from a random index for each request.
+Proxy URL(s). If multiple values are provided, Sarin starts at a random index and cycles through them in order. Once the cycle completes, it picks a new random starting point.
 
 Supported protocols: `http`, `https`, `socks5`, `socks5h`
 
@@ -356,9 +390,9 @@ proxy: http://proxy1.com
 # OR
 
 proxy:
-  - http://proxy1.com
+    - http://proxy1.com
-  - socks5://proxy2.com
+    - socks5://proxy2.com
-  - socks5h://proxy3.com
+    - socks5h://proxy3.com
 ```
 
 **CLI example:**
@@ -387,9 +421,9 @@ values: "key=value"
 # OR
 
 values: |
-  key1=value1
+    key1=value1
-  key2=value2
+    key2=value2
-  key3=value3
+    key3=value3
 ```
 
 **CLI example:**
@@ -435,7 +469,9 @@ function transform(req)
 end
 ```
 
-> **Note:** Header, parameter, and cookie values can be a single string or a table (array) for multiple values per key (e.g. `{"val1", "val2"}`).
+> **Note:** Header, parameter, and cookie values can be a single string or a table (array) for multiple values per key (e.g. `{"val1", "val2"}`). Numbers and booleans are converted to text, other values are skipped.
+
+> **Note:** Lua scripts can send their own HTTP requests with `http` and work with JSON through the global `json` table. See [HTTP Requests in Scripts](#http-requests-in-scripts).
 
 **YAML example:**
 
@@ -500,7 +536,9 @@ function transform(req) {
 }
 ```
 
-> **Note:** Header, parameter, and cookie values can be a single string or an array for multiple values per key (e.g. `["val1", "val2"]`).
+> **Note:** Header, parameter, and cookie values can be a single string or an array for multiple values per key (e.g. `["val1", "val2"]`). Numbers and booleans are converted to text, other values are skipped.
+
+> **Note:** JavaScript scripts can send their own HTTP requests with `http`. See [HTTP Requests in Scripts](#http-requests-in-scripts).
 
 **YAML example:**
 
@@ -533,3 +571,104 @@ js:
 ```sh
 SARIN_JS='function transform(req) { req.headers["X-Custom"] = "my-value"; return req; }'
 ```
+
+## HTTP Requests in Scripts
+
+Lua and JavaScript scripts can send their own HTTP requests and use the response in the main request, for example to fetch a fresh token or CSRF value from another endpoint.
+
+**Function:**
+
+```
+http(url, opts)
+```
+
+`url` must be an absolute `http` or `https` URL. `opts` is optional.
+
+**Options:**
+
+| Option         | Type                        | Default | Description                                                                                            |
+| -------------- | --------------------------- | ------- | ------------------------------------------------------------------------------------------------------ |
+| `method`       | string                      | `GET`   | HTTP method, sent as given                                                                             |
+| `headers`      | table/object                | -       | Request headers, same shape as `req.headers`                                                           |
+| `params`       | table/object                | -       | Query parameters, added to any already in the URL                                                      |
+| `cookies`      | table/object                | -       | Cookies, sent as a single `Cookie` header                                                              |
+| `body`         | string                      | `""`    | Request body                                                                                           |
+| `timeout`      | duration string (`"500ms"`) | `30s`   | Request timeout (the `timeout` config does not apply), applied to each hop when redirects are followed |
+| `insecure`     | boolean                     | `false` | Skip TLS verification (the `insecure` config does not apply)                                           |
+| `maxRedirects` | number                      | `0`     | How many redirects to follow, `0` follows none, maximum 100                                            |
+
+Unknown options and values of the wrong type raise an error.
+
+**Response:**
+
+| Field / Method | Description                                                        |
+| -------------- | ------------------------------------------------------------------ |
+| `status`       | Status code (number)                                               |
+| `headers`      | Response headers, each key holding an array of values              |
+| `body`         | Response body (string)                                             |
+| `header(name)` | First value of a header, case-insensitive; `nil`/`null` if missing |
+| `cookie(name)` | Value of a cookie from `Set-Cookie`; `nil`/`null` if missing       |
+| `json()`       | JavaScript only: parses the body as JSON                           |
+| `bytes()`      | JavaScript only: the body as a `Uint8Array`                        |
+
+In Lua, call the helpers as `res:header("name")` or `res.header("name")`.
+
+> **Note:** JavaScript strings hold UTF-16, so `body` replaces bytes that are not valid UTF-8 and `body.length` counts code units rather than bytes. Use `bytes()` for binary responses and for the real byte count. Lua strings keep the bytes as they arrived.
+
+**Behavior:**
+
+- **Runs on every request:** the requests are sent each time `transform` runs, so every main request triggers them. Script globals persist across requests within a worker, so a script can cache a value itself (e.g. `if not token then token = login() end`).
+- **Same proxy:** when proxies are configured, a script's requests go through the same proxy as the main request they belong to.
+- **Status codes:** non-2xx responses are returned normally; check `status` in the script.
+- **Errors:** network failures and timeouts raise a script error. The main request is not sent and the error is counted in the results. Scripts can catch it with `pcall` (Lua) or `try`/`catch` (JavaScript).
+- **Response bodies:** the [Max Response Body](#max-response-body) config bounds these requests too, and a body above it raises an error the script can catch.
+- **Only inside `transform`:** `http` works anywhere while `transform` runs, including in helper functions it calls. Calling it at the top level of a script raises an error, because that code also runs during config validation and when each worker starts.
+- **Dry run:** script requests are still sent in dry-run mode.
+- **Not measured:** script requests are not included in the results.
+
+**Lua JSON:**
+
+Lua has no built-in JSON support, so Lua scripts get a global `json` table:
+
+- `json.decode(string)`: arrays become 1-indexed tables and `null` becomes `nil` (so `null` array items leave holes).
+- `json.encode(value)`: a table with keys exactly `1..n` becomes an array, any other table becomes an object, and an empty table becomes `{}`.
+
+JavaScript scripts use the built-in `JSON` object.
+
+**Lua example:**
+
+```lua
+function transform(req)
+    local res = http("https://api.example.com/login", {
+        method = "POST",
+        headers = { ["Content-Type"] = "application/json" },
+        body = json.encode({ user = "test", password = "secret" }),
+        timeout = "2s",
+    })
+    if res.status ~= 200 then
+        error("login failed: " .. res.status)
+    end
+
+    req.headers["Authorization"] = "Bearer " .. json.decode(res.body).token
+    return req
+end
+```
+
+**JavaScript example:**
+
+```javascript
+function transform(req) {
+    const res = http("https://api.example.com/login", {
+        method: "POST",
+        headers: { "Content-Type": "application/json" },
+        body: JSON.stringify({ user: "test", password: "secret" }),
+        timeout: "2s",
+    });
+    if (res.status !== 200) {
+        throw new Error("login failed: " + res.status);
+    }
+
+    req.headers["Authorization"] = "Bearer " + res.json().token;
+    return req;
+}
+```

docs/examples.md

@@ -13,6 +13,7 @@ This guide provides practical examples for common Sarin use cases.
 - [File Uploads](#file-uploads)
 - [Using Proxies](#using-proxies)
 - [Output Formats](#output-formats)
+- [Runtime Logging](#runtime-logging)
 - [Docker Usage](#docker-usage)
 - [Dry Run Mode](#dry-run-mode)
 - [Show Configuration](#show-configuration)
@@ -372,7 +373,7 @@ body: '{"ip": "{{ fakeit_IPv4Address }}", "timestamp": "{{ fakeit_Date }}", "act
 
 </details>
 
-> For the complete list of 340+ template functions, see the **[Templating Guide](templating.md)**.
+> For the complete list of 370+ template functions, see the **[Templating Guide](templating.md)**.
 
 ## Solving Captchas
 
@@ -719,7 +720,7 @@ proxy: socks5://proxy.example.com:1080
 
 </details>
 
-**Multiple proxies (load balanced):**
+**Multiple proxies (randomly cycled):**
 
 ```sh
 sarin -U http://example.com -r 1000 -c 10 \
@@ -836,10 +837,10 @@ output: none
 
 </details>
 
-**Quiet mode (hide progress bar):**
+**Hide the progress bar:**
 
 ```sh
-sarin -U http://example.com -r 1000 -c 10 -q
+sarin -U http://example.com -r 1000 -c 10 -p none
 ```
 
 <details>
@@ -849,7 +850,42 @@ sarin -U http://example.com -r 1000 -c 10 -q
 url: http://example.com
 requests: 1000
 concurrency: 10
-quiet: true
+progress: none
+```
+
+</details>
+
+## Runtime Logging
+
+`--log-level` selects which runtime logs Sarin emits (comma-separated `info` and `error`, default `error`). `error` covers request and generation errors, `info` covers every completed response (status, duration, headers, body). Logs appear in the progress log box on an interactive terminal, go to stderr when piped, or go to a file with `--log-file`.
+
+**Log responses and errors:**
+
+```sh
+sarin -U http://example.com -r 1000 -c 10 -l info,error
+```
+
+**Write logs to a file (the progress bar stays on screen):**
+
+```sh
+sarin -U http://example.com -r 1000 -c 10 -l info --log-file ./run.log
+```
+
+**Capture logs while keeping results on stdout:**
+
+```sh
+sarin -U http://example.com -r 1000 -l info -o json > stats.json 2> run.log
+```
+
+<details>
+<summary>YAML equivalent</summary>
+
+```yaml
+url: http://example.com
+requests: 1000
+concurrency: 10
+logLevel: info,error
+logFile: ./run.log
 ```
 
 </details>
@@ -1051,3 +1087,139 @@ js: "@./scripts/body.js"
 ```
 
 </details>
+
+**Fetch a value from another endpoint before each request:**
+
+Scripts can send their own requests with `http`. Here each request first fetches a CSRF token and sends it in a header and cookie. See [HTTP Requests in Scripts](configuration.md#http-requests-in-scripts) for all options.
+
+```sh
+sarin -U http://example.com/api/orders -r 1000 -c 10 \
+  -M POST \
+  -lua 'function transform(req)
+    local res = http("http://example.com/csrf")
+    req.headers["X-CSRF-Token"] = json.decode(res.body).token
+    req.cookies["session"] = res:cookie("session")
+    return req
+  end'
+```
+
+<details>
+<summary>YAML equivalent</summary>
+
+```yaml
+url: http://example.com/api/orders
+requests: 1000
+concurrency: 10
+method: POST
+lua: |
+    function transform(req)
+        local res = http("http://example.com/csrf")
+        req.headers["X-CSRF-Token"] = json.decode(res.body).token
+        req.cookies["session"] = res:cookie("session")
+        return req
+    end
+```
+
+</details>
+
+**Log in once per worker and reuse the token (JavaScript):**
+
+```yaml
+url: http://example.com/api/profile
+requests: 1000
+concurrency: 10
+js: |
+    let token;
+
+    function login() {
+        const res = http("http://example.com/login", {
+            method: "POST",
+            headers: { "Content-Type": "application/json" },
+            body: JSON.stringify({ user: "test", password: "secret" }),
+        });
+        if (res.status !== 200) throw new Error("login failed: " + res.status);
+        return res.json().token;
+    }
+
+    function transform(req) {
+        if (!token) token = login();
+        req.headers["Authorization"] = "Bearer " + token;
+        return req;
+    }
+```
+
+**Chain two calls, then use the result in the URL path (Lua):**
+
+```yaml
+url: http://example.com/api/placeholder
+requests: 500
+concurrency: 10
+lua: |
+    function transform(req)
+        local token = json.decode(http("http://example.com/login", {
+            method = "POST",
+            body = json.encode({ user = "test", password = "secret" }),
+            headers = { ["Content-Type"] = "application/json" },
+        }).body).token
+
+        local orders = json.decode(http("http://example.com/api/orders", {
+            headers = { Authorization = "Bearer " .. token },
+        }).body)
+
+        req.path = "/api/orders/" .. orders[1].id
+        req.headers["Authorization"] = "Bearer " .. token
+        return req
+    end
+```
+
+**Refresh a token only when it expires (JavaScript):**
+
+```yaml
+url: http://example.com/api/profile
+requests: 5000
+concurrency: 20
+js: |
+    let token;
+    let expiresAt = 0;
+
+    function transform(req) {
+        if (Date.now() >= expiresAt) {
+            const res = http("http://example.com/login", { method: "POST", body: "{}" });
+            token = res.json().token;
+            expiresAt = Date.now() + 60000; // refresh once a minute per worker
+        }
+        req.headers["Authorization"] = "Bearer " + token;
+        return req;
+    }
+```
+
+**Keep sending the main request even when the extra call fails:**
+
+A failed `http` call raises an error, which skips the main request and records the failure in the results. Catch it to decide yourself:
+
+```sh
+sarin -U http://example.com/api/items -r 1000 -c 10 \
+  -lua 'function transform(req)
+    local ok, res = pcall(http, "http://example.com/api/flags")
+    if ok and res.status == 200 then
+      req.headers["X-Flags"] = res.body
+    else
+      req.headers["X-Flags"] = "default"
+    end
+    return req
+  end'
+```
+
+The JavaScript equivalent:
+
+```sh
+sarin -U http://example.com/api/items -r 1000 -c 10 \
+  -js 'function transform(req) {
+    try {
+      req.headers["X-Flags"] = http("http://example.com/api/flags").body;
+    } catch (e) {
+      req.headers["X-Flags"] = "default";
+    }
+    return req;
+  }'
+```

docs/templating.md

@@ -4,7 +4,7 @@ Sarin supports Go templates in URL paths, methods, bodies, headers, params, cook
 
 > **Note:** Templating in URL host and scheme is not supported. Only the path portion of the URL can contain templates.
 
-> **Note:** Template rendering happens before the request is sent. The request timeout (`-T` / `timeout`) only governs the HTTP request itself and starts _after_ templates have finished rendering, so slow template functions (e.g. captcha solvers, remote `file_Read`) cannot cause a request timeout no matter how long they take.
+> **Note:** Template rendering happens before the request is sent. The request timeout (`-T` / `timeout`) only governs the HTTP request itself and starts _after_ templates have finished rendering, so slow template functions (e.g. captcha solvers, remote `file_Read`) cannot cause a request timeout no matter how long they take. Downloads have their own limits: 30 seconds and 64MiB per file.
 
 ## Table of Contents
 
@@ -183,19 +183,19 @@ body: '{{ body_FormData "image" "@https://example.com/photo.jpg" }}'
 
 # Mixed text fields and files
 body: |
-  {{ body_FormData
+    {{ body_FormData
-     "title" "My Report"
+       "title" "My Report"
-     "author" "John Doe"
+       "author" "John Doe"
-     "cover" "@/path/to/cover.jpg"
+       "cover" "@/path/to/cover.jpg"
-     "document" "@/path/to/report.pdf"
+       "document" "@/path/to/report.pdf"
-  }}
+    }}
 
 # Multiple files with same field name
 body: |
-  {{ body_FormData
+    {{ body_FormData
-     "files" "@/path/to/file1.pdf"
+       "files" "@/path/to/file1.pdf"
-     "files" "@/path/to/file2.pdf"
+       "files" "@/path/to/file2.pdf"
-  }}
+    }}
 
 # Escape @ for literal value (sends "@username")
 body: '{{ body_FormData "twitter" "@@username" }}'
@@ -226,7 +226,7 @@ body: '{"file": "{{ file_Base64 "/path/to/document.pdf" }}", "filename": "docume
 body: '{"image": "{{ file_Base64 "https://example.com/photo.jpg" }}"}'
 
 # Combined with values for reuse
-values: "FILE_DATA={{ file_Base64 \"/path/to/file.bin\" }}"
+values: 'FILE_DATA={{ file_Base64 "/path/to/file.bin" }}'
 body: '{"data": "{{ .Values.FILE_DATA }}"}'
 ```
 
@@ -234,7 +234,7 @@ body: '{"data": "{{ .Values.FILE_DATA }}"}'
 
 Captcha functions solve a captcha challenge through a third-party solving service and return the resulting token, which can then be embedded directly into a request. They are intended for load testing endpoints protected by reCAPTCHA, hCaptcha, or Cloudflare Turnstile.
 
-The functions are organized by service: `twocaptcha_*`, `anticaptcha_*`, and `capsolver_*`. Each accepts the API key as the first argument so no global configuration is required — bring your own key and use any of the supported services per template.
+The functions are organized by service: `twocaptcha_*`, `anticaptcha_*`, and `capsolver_*`. Each accepts the API key as the first argument so no global configuration is required. Bring your own key and use any of the supported services per template.
 
 > **Important: performance and cost:**
 >
@@ -249,7 +249,7 @@ The functions are organized by service: `twocaptcha_*`, `anticaptcha_*`, and `ca
 
 ### 2Captcha
 
-Functions for the [2Captcha](https://2captcha.com) service. Note: 2Captcha **does not currently support hCaptcha** through their API.
+Functions for the [2Captcha](https://2captcha.com) service. Sarin supports reCAPTCHA v2, reCAPTCHA v3, and Cloudflare Turnstile through this integration.
 
 | Function                                                                 | Description                                                               |
 | ------------------------------------------------------------------------ | ------------------------------------------------------------------------- |
@@ -259,7 +259,7 @@ Functions for the [2Captcha](https://2captcha.com) service. Note: 2Captcha **doe
 
 ### Anti-Captcha
 
-Functions for the [Anti-Captcha](https://anti-captcha.com) service. This is currently the only service that supports all four captcha types end-to-end.
+Functions for the [Anti-Captcha](https://anti-captcha.com) service. This is the only Sarin captcha integration that exposes an hCaptcha function.
 
 | Function                                                                  | Description                                                                                                           |
 | ------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------- |
@@ -270,7 +270,7 @@ Functions for the [Anti-Captcha](https://anti-captcha.com) service. This is curr
 
 ### CapSolver
 
-Functions for the [CapSolver](https://capsolver.com) service. Note: CapSolver no longer supports hCaptcha.
+Functions for the [CapSolver](https://capsolver.com) service. Sarin supports reCAPTCHA v2, reCAPTCHA v3, and Cloudflare Turnstile through this integration.
 
 | Function                                                                | Description                                                               |
 | ----------------------------------------------------------------------- | ------------------------------------------------------------------------- |
@@ -302,7 +302,7 @@ body: |
 ```
 
 ```yaml
-# hCaptcha via Anti-Captcha (the only service that still supports it)
+# hCaptcha via Anti-Captcha
 method: POST
 url: https://example.com/protected
 body: |
@@ -325,10 +325,10 @@ These functions are powered by [gofakeit](https://github.com/brianvoe/gofakeit)
 
 ### File
 
-| Function               | Description    | Example Output       |
+| Function               | Description    | Example Output        |
-| ---------------------- | -------------- | -------------------- |
+| ---------------------- | -------------- | --------------------- |
-| `fakeit_FileExtension` | File extension | `"nes"`              |
+| `fakeit_FileExtension` | File extension | `"nes"`               |
-| `fakeit_FileMimeType`  | MIME type      | `"application/json"` |
+| `fakeit_FileMimeType`  | MIME type      | `"application/x-wri"` |
 
 ### ID
 
@@ -347,7 +347,7 @@ These functions are powered by [gofakeit](https://github.com/brianvoe/gofakeit)
 | `fakeit_ProductFeature`     | Product feature     | `"ultra-lightweight"`             |
 | `fakeit_ProductMaterial`    | Product material    | `"brass"`                         |
 | `fakeit_ProductUPC`         | UPC code            | `"012780949980"`                  |
-| `fakeit_ProductAudience`    | Target audience     | `["adults"]`                      |
+| `fakeit_ProductAudience`    | Target audience     | `[adults]`                        |
 | `fakeit_ProductDimension`   | Product dimension   | `"medium"`                        |
 | `fakeit_ProductUseCase`     | Use case            | `"home"`                          |
 | `fakeit_ProductBenefit`     | Product benefit     | `"comfort"`                       |
@@ -356,23 +356,25 @@ These functions are powered by [gofakeit](https://github.com/brianvoe/gofakeit)
 
 ### Person
 
-| Function                | Description            | Example Output           |
+| Function                | Description            | Example Output                                                      |
-| ----------------------- | ---------------------- | ------------------------ |
+| ----------------------- | ---------------------- | ------------------------------------------------------------------- |
-| `fakeit_Name`           | Full name              | `"Markus Moen"`          |
+| `fakeit_Name`           | Full name              | `"Priscilla Thornton"`                                              |
-| `fakeit_NamePrefix`     | Name prefix            | `"Mr."`                  |
+| `fakeit_NamePrefix`     | Name prefix            | `"Mr."`                                                             |
-| `fakeit_NameSuffix`     | Name suffix            | `"Jr."`                  |
+| `fakeit_NameSuffix`     | Name suffix            | `"Jr."`                                                             |
-| `fakeit_FirstName`      | First name             | `"Markus"`               |
+| `fakeit_FirstName`      | First name             | `"Priscilla"`                                                       |
-| `fakeit_MiddleName`     | Middle name            | `"Belinda"`              |
+| `fakeit_MiddleName`     | Middle name            | `"Belinda"`                                                         |
-| `fakeit_LastName`       | Last name              | `"Daniel"`               |
+| `fakeit_LastName`       | Last name              | `"Daniel"`                                                          |
-| `fakeit_Gender`         | Gender                 | `"male"`                 |
+| `fakeit_Gender`         | Gender                 | `"male"`                                                            |
-| `fakeit_Age`            | Age                    | `40`                     |
+| `fakeit_Age`            | Age                    | `40`                                                                |
-| `fakeit_Ethnicity`      | Ethnicity              | `"German"`               |
+| `fakeit_Ethnicity`      | Ethnicity              | `"German"`                                                          |
-| `fakeit_SSN`            | Social Security Number | `"296446360"`            |
+| `fakeit_SSN`            | Social Security Number | `"296446360"`                                                       |
-| `fakeit_EIN`            | Employer ID Number     | `"12-3456789"`           |
+| `fakeit_EIN`            | Employer ID Number     | `"12-3456789"`                                                      |
-| `fakeit_Hobby`          | Hobby                  | `"Swimming"`             |
+| `fakeit_Hobby`          | Hobby                  | `"Swimming"`                                                        |
-| `fakeit_Email`          | Email address          | `"markusmoen@pagac.net"` |
+| `fakeit_SocialMedia`    | Social media profile   | `"https://twitter.com/ImpossibleTrousers"`                          |
-| `fakeit_Phone`          | Phone number           | `"6136459948"`           |
+| `fakeit_Bio`            | Biography              | `"Born in New York, John grew up to become a Software Engineer..."` |
-| `fakeit_PhoneFormatted` | Formatted phone        | `"136-459-9489"`         |
+| `fakeit_Email`          | Email address          | `"priscilla.thornton@duncan.biz"`                                   |
+| `fakeit_Phone`          | Phone number           | `"6136459948"`                                                      |
+| `fakeit_PhoneFormatted` | Formatted phone        | `"136-459-9489"`                                                    |
 
 ### Generate
 
@@ -391,7 +393,7 @@ These functions are powered by [gofakeit](https://github.com/brianvoe/gofakeit)
 
 | Function                                            | Description                  | Example Output                                       |
 | --------------------------------------------------- | ---------------------------- | ---------------------------------------------------- |
-| `fakeit_City`                                       | City name                    | `"Marcelside"`                                       |
+| `fakeit_City`                                       | City name                    | `"Reno"`                                             |
 | `fakeit_Country`                                    | Country name                 | `"United States of America"`                         |
 | `fakeit_CountryAbr`                                 | Country abbreviation         | `"US"`                                               |
 | `fakeit_State`                                      | State name                   | `"Illinois"`                                         |
@@ -400,7 +402,7 @@ These functions are powered by [gofakeit](https://github.com/brianvoe/gofakeit)
 | `fakeit_StreetName`                                 | Street name                  | `"View"`                                             |
 | `fakeit_StreetNumber`                               | Street number                | `"13645"`                                            |
 | `fakeit_StreetPrefix`                               | Street prefix                | `"East"`                                             |
-| `fakeit_StreetSuffix`                               | Street suffix                | `"Ave"`                                              |
+| `fakeit_StreetSuffix`                               | Street suffix                | `"side"`                                             |
 | `fakeit_Unit`                                       | Unit                         | `"Apt 123"`                                          |
 | `fakeit_Zip`                                        | ZIP code                     | `"13645"`                                            |
 | `fakeit_Latitude`                                   | Random latitude              | `-73.534056`                                         |
@@ -408,11 +410,23 @@ These functions are powered by [gofakeit](https://github.com/brianvoe/gofakeit)
 | `fakeit_LatitudeInRange(min float64, max float64)`  | Latitude in specified range  | `{{ fakeit_LatitudeInRange 0 90 }}` → `22.921026`    |
 | `fakeit_LongitudeInRange(min float64, max float64)` | Longitude in specified range | `{{ fakeit_LongitudeInRange 0 180 }}` → `122.471830` |
 
+### Airline
+
+| Function                      | Description       | Example Output                                       |
+| ----------------------------- | ----------------- | ---------------------------------------------------- |
+| `fakeit_AirlineAircraftType`  | Aircraft type     | `"narrowbody"`                                       |
+| `fakeit_AirlineAirplane`      | Airplane model    | `"Airbus A320"`                                      |
+| `fakeit_AirlineAirport`       | Airport name      | `"Hartsfield-Jackson Atlanta International Airport"` |
+| `fakeit_AirlineAirportIATA`   | Airport IATA code | `"ATL"`                                              |
+| `fakeit_AirlineFlightNumber`  | Flight number     | `"AA1234"`                                           |
+| `fakeit_AirlineRecordLocator` | Booking reference | `"ABCDEF"`                                           |
+| `fakeit_AirlineSeat`          | Seat assignment   | `"12A"`                                              |
+
 ### Game
 
-| Function          | Description | Example Output      |
+| Function          | Description | Example Output    |
-| ----------------- | ----------- | ------------------- |
+| ----------------- | ----------- | ----------------- |
-| `fakeit_Gamertag` | Gamer tag   | `"footinterpret63"` |
+| `fakeit_Gamertag` | Gamer tag   | `"TurkeyThinker"` |
 
 ### Beer
 
@@ -443,18 +457,22 @@ These functions are powered by [gofakeit](https://github.com/brianvoe/gofakeit)
 | ---------------------------------- | --------------------------- | ---------------- |
 | `fakeit_Word`                      | Random word                 | `"example"`      |
 | `fakeit_Noun`                      | Random noun                 | `"computer"`     |
-| `fakeit_NounCommon`                | Common noun                 | `"table"`        |
+| `fakeit_NounCommon`                | Common noun                 | `"group"`        |
 | `fakeit_NounConcrete`              | Concrete noun               | `"chair"`        |
 | `fakeit_NounAbstract`              | Abstract noun               | `"freedom"`      |
 | `fakeit_NounCollectivePeople`      | Collective noun (people)    | `"team"`         |
-| `fakeit_NounCollectiveAnimal`      | Collective noun (animal)    | `"herd"`         |
+| `fakeit_NounCollectiveAnimal`      | Collective noun (animal)    | `"leap"`         |
 | `fakeit_NounCollectiveThing`       | Collective noun (thing)     | `"bunch"`        |
 | `fakeit_NounCountable`             | Countable noun              | `"book"`         |
 | `fakeit_NounUncountable`           | Uncountable noun            | `"water"`        |
-| `fakeit_Verb`                      | Random verb                 | `"run"`          |
+| `fakeit_NounProper`                | Proper noun                 | `"John"`         |
+| `fakeit_NounDeterminer`            | Noun determiner             | `"your"`         |
+| `fakeit_Verb`                      | Random verb                 | `"would"`        |
 | `fakeit_VerbAction`                | Action verb                 | `"jump"`         |
 | `fakeit_VerbLinking`               | Linking verb                | `"is"`           |
 | `fakeit_VerbHelping`               | Helping verb                | `"can"`          |
+| `fakeit_VerbTransitive`            | Transitive verb             | `"follow"`       |
+| `fakeit_VerbIntransitive`          | Intransitive verb           | `"laugh"`        |
 | `fakeit_Adverb`                    | Random adverb               | `"quickly"`      |
 | `fakeit_AdverbManner`              | Manner adverb               | `"carefully"`    |
 | `fakeit_AdverbDegree`              | Degree adverb               | `"very"`         |
@@ -468,7 +486,7 @@ These functions are powered by [gofakeit](https://github.com/brianvoe/gofakeit)
 | `fakeit_PrepositionDouble`         | Double preposition          | `"out of"`       |
 | `fakeit_PrepositionCompound`       | Compound preposition        | `"according to"` |
 | `fakeit_Adjective`                 | Random adjective            | `"beautiful"`    |
-| `fakeit_AdjectiveDescriptive`      | Descriptive adjective       | `"large"`        |
+| `fakeit_AdjectiveDescriptive`      | Descriptive adjective       | `"tired"`        |
 | `fakeit_AdjectiveQuantitative`     | Quantitative adjective      | `"many"`         |
 | `fakeit_AdjectiveProper`           | Proper adjective            | `"American"`     |
 | `fakeit_AdjectiveDemonstrative`    | Demonstrative adjective     | `"this"`         |
@@ -483,26 +501,33 @@ These functions are powered by [gofakeit](https://github.com/brianvoe/gofakeit)
 | `fakeit_PronounDemonstrative`      | Demonstrative pronoun       | `"that"`         |
 | `fakeit_PronounInterrogative`      | Interrogative pronoun       | `"who"`          |
 | `fakeit_PronounRelative`           | Relative pronoun            | `"which"`        |
+| `fakeit_PronounIndefinite`         | Indefinite pronoun          | `"few"`          |
 | `fakeit_Connective`                | Random connective           | `"however"`      |
 | `fakeit_ConnectiveTime`            | Time connective             | `"then"`         |
-| `fakeit_ConnectiveComparative`     | Comparative connective      | `"similarly"`    |
+| `fakeit_ConnectiveComparative`     | Comparative connective      | `"after all"`    |
-| `fakeit_ConnectiveComplaint`       | Complaint connective        | `"although"`     |
+| `fakeit_ConnectiveComplaint`       | Complaint connective        | `"i.e."`         |
 | `fakeit_ConnectiveListing`         | Listing connective          | `"firstly"`      |
 | `fakeit_ConnectiveCasual`          | Casual connective           | `"because"`      |
 | `fakeit_ConnectiveExamplify`       | Examplify connective        | `"for example"`  |
+| `fakeit_Interjection`              | Interjection                | `"wow"`          |
 
 ### Text
 
-| Function                                                                                 | Description                                     | Example                                               |
+| Function                                                                                 | Description                                     | Example                                       |
-| ---------------------------------------------------------------------------------------- | ----------------------------------------------- | ----------------------------------------------------- |
+| ---------------------------------------------------------------------------------------- | ----------------------------------------------- | --------------------------------------------- |
-| `fakeit_Sentence(wordCount ...int)`                                                      | Random sentence (optional word count)           | `{{ fakeit_Sentence }}` or `{{ fakeit_Sentence 10 }}` |
+| `fakeit_Sentence`                                                                        | Random sentence                                 | `{{ fakeit_Sentence }}`                       |
-| `fakeit_Paragraph`                                                                       | Random paragraph                                | `{{ fakeit_Paragraph }}`                              |
+| `fakeit_Paragraph`                                                                       | Random paragraph                                | `{{ fakeit_Paragraph }}`                      |
-| `fakeit_LoremIpsumWord`                                                                  | Lorem ipsum word                                | `"lorem"`                                             |
+| `fakeit_LoremIpsumWord`                                                                  | Lorem ipsum word                                | `"eveniet"`                                   |
-| `fakeit_LoremIpsumSentence(wordCount int)`                                               | Lorem ipsum sentence with specified word count  | `{{ fakeit_LoremIpsumSentence 5 }}`                   |
+| `fakeit_LoremIpsumSentence(wordCount int)`                                               | Lorem ipsum sentence with specified word count  | `{{ fakeit_LoremIpsumSentence 5 }}`           |
-| `fakeit_LoremIpsumParagraph(paragraphs int, sentences int, words int, separator string)` | Lorem ipsum paragraphs with specified structure | `{{ fakeit_LoremIpsumParagraph 1 3 5 "\n" }}`         |
+| `fakeit_LoremIpsumParagraph(paragraphs int, sentences int, words int, separator string)` | Lorem ipsum paragraphs with specified structure | `{{ fakeit_LoremIpsumParagraph 1 3 5 "\n" }}` |
-| `fakeit_Question`                                                                        | Random question                                 | `"What is your name?"`                                |
+| `fakeit_Question`                                                                        | Random question                                 | `"What is the marginal gain from fear?"`      |
-| `fakeit_Quote`                                                                           | Random quote                                    | `"Life is what happens..."`                           |
+| `fakeit_Quote`                                                                           | Random quote                                    | `"Energy is contagious so is fear"`           |
-| `fakeit_Phrase`                                                                          | Random phrase                                   | `"a piece of cake"`                                   |
+| `fakeit_Phrase`                                                                          | Random phrase                                   | `"how many siblings do you have"`             |
+| `fakeit_PhraseNoun`                                                                      | Noun phrase                                     | `"a tribe"`                                   |
+| `fakeit_PhraseVerb`                                                                      | Verb phrase                                     | `"fully integrate a system"`                  |
+| `fakeit_PhraseAdverb`                                                                    | Adverb phrase                                   | `"fully gladly"`                              |
+| `fakeit_PhrasePreposition`                                                               | Preposition phrase                              | `"out the black thing"`                       |
+| `fakeit_Comment`                                                                         | Comment                                         | `"add some a little bit team"`                |
 
 ### Foods
 
@@ -515,6 +540,7 @@ These functions are powered by [gofakeit](https://github.com/brianvoe/gofakeit)
 | `fakeit_Dinner`    | Dinner food    | `"Wild addicting dip"`                   |
 | `fakeit_Snack`     | Snack          | `"Trail mix"`                            |
 | `fakeit_Dessert`   | Dessert        | `"French napoleons"`                     |
+| `fakeit_Drink`     | Drink          | `"Soda"`                                 |
 
 ### Misc
 
@@ -525,20 +551,23 @@ These functions are powered by [gofakeit](https://github.com/brianvoe/gofakeit)
 
 ### Color
 
-| Function            | Description        | Example Output                                            |
+| Function            | Description        | Example Output                              |
-| ------------------- | ------------------ | --------------------------------------------------------- |
+| ------------------- | ------------------ | ------------------------------------------- |
-| `fakeit_Color`      | Color name         | `"MediumOrchid"`                                          |
+| `fakeit_Color`      | Color name         | `"MediumOrchid"`                            |
-| `fakeit_HexColor`   | Hex color          | `"#a99fb4"`                                               |
+| `fakeit_HexColor`   | Hex color          | `"#a99fb4"`                                 |
-| `fakeit_RGBColor`   | RGB color          | `[85, 224, 195]`                                          |
+| `fakeit_RGBColor`   | RGB color          | `[85 224 195]`                              |
-| `fakeit_SafeColor`  | Safe color         | `"black"`                                                 |
+| `fakeit_HSLColor`   | HSL color          | `[210 85 50]`                               |
-| `fakeit_NiceColors` | Nice color palette | `["#cfffdd", "#b4dec1", "#5c5863", "#a85163", "#ff1f4c"]` |
+| `fakeit_SafeColor`  | Safe color         | `"black"`                                   |
+| `fakeit_NiceColors` | Nice color palette | `[#cfffdd #b4dec1 #5c5863 #a85163 #ff1f4c]` |
 
 ### Image
 
-| Function                                  | Description               | Example                          |
+| Function                                  | Description                | Example                          |
-| ----------------------------------------- | ------------------------- | -------------------------------- |
+| ----------------------------------------- | -------------------------- | -------------------------------- |
-| `fakeit_ImageJpeg(width int, height int)` | Generate JPEG image bytes | `{{ fakeit_ImageJpeg 100 100 }}` |
+| `fakeit_ImageJpeg(width int, height int)` | Generate a JPEG byte slice | `{{ fakeit_ImageJpeg 100 100 }}` |
-| `fakeit_ImagePng(width int, height int)`  | Generate PNG image bytes  | `{{ fakeit_ImagePng 100 100 }}`  |
+| `fakeit_ImagePng(width int, height int)`  | Generate a PNG byte slice  | `{{ fakeit_ImagePng 100 100 }}`  |
+
+> **Note:** Go templates render byte slices as decimal lists, not raw binary image data. Use `{{ json_Encode (fakeit_ImagePng 100 100) }}` to produce a Base64-encoded JSON string. These functions cannot write raw image bytes directly through body templating.
 
 ### Internet
 
@@ -567,16 +596,16 @@ These functions are powered by [gofakeit](https://github.com/brianvoe/gofakeit)
 
 | Function           | Description     | Example Output     |
 | ------------------ | --------------- | ------------------ |
-| `fakeit_InputName` | HTML input name | `"email"`          |
+| `fakeit_InputName` | HTML input name | `"message"`        |
 | `fakeit_Svg`       | SVG image       | `"<svg>...</svg>"` |
 
 ### Date/Time
 
 | Function                                           | Description                       | Example                                                                              |
 | -------------------------------------------------- | --------------------------------- | ------------------------------------------------------------------------------------ |
-| `fakeit_Date`                                      | Random date                       | `2023-06-15 14:30:00`                                                                |
+| `fakeit_Date`                                      | Random date                       | `2013-11-07 04:31:13.726582492 +0000 UTC`                                            |
-| `fakeit_PastDate`                                  | Past date                         | `2022-03-10 09:15:00`                                                                |
+| `fakeit_PastDate`                                  | Date 1–12 hours before now        | Current time − 1–12 hours                                                            |
-| `fakeit_FutureDate`                                | Future date                       | `2025-12-20 18:45:00`                                                                |
+| `fakeit_FutureDate`                                | Date 1–12 hours after now         | Current time + 1–12 hours                                                            |
 | `fakeit_DateRange(start time.Time, end time.Time)` | Random date between start and end | `{{ fakeit_DateRange (strings_ToDate "2020-01-01") (strings_ToDate "2025-12-31") }}` |
 | `fakeit_NanoSecond`                                | Nanosecond                        | `123456789`                                                                          |
 | `fakeit_Second`                                    | Second (0-59)                     | `45`                                                                                 |
@@ -587,11 +616,11 @@ These functions are powered by [gofakeit](https://github.com/brianvoe/gofakeit)
 | `fakeit_Day`                                       | Day (1-31)                        | `15`                                                                                 |
 | `fakeit_WeekDay`                                   | Weekday                           | `"Monday"`                                                                           |
 | `fakeit_Year`                                      | Year                              | `2024`                                                                               |
-| `fakeit_TimeZone`                                  | Timezone                          | `"America/New_York"`                                                                 |
+| `fakeit_TimeZone`                                  | Timezone name                     | `"West Pacific Standard Time"`                                                       |
 | `fakeit_TimeZoneAbv`                               | Timezone abbreviation             | `"EST"`                                                                              |
-| `fakeit_TimeZoneFull`                              | Full timezone                     | `"Eastern Standard Time"`                                                            |
+| `fakeit_TimeZoneFull`                              | Full timezone                     | `"(UTC+10:00) Guam, Port Moresby"`                                                   |
 | `fakeit_TimeZoneOffset`                            | Timezone offset                   | `-5`                                                                                 |
-| `fakeit_TimeZoneRegion`                            | Timezone region                   | `"America"`                                                                          |
+| `fakeit_TimeZoneRegion`                            | Timezone region                   | `"Indian/Chagos"`                                                                    |
 
 ### Payment
 
@@ -607,8 +636,8 @@ These functions are powered by [gofakeit](https://github.com/brianvoe/gofakeit)
 | `fakeit_AchRouting`                      | ACH routing number                                    | `"513715684"`                                                  |
 | `fakeit_AchAccount`                      | ACH account number                                    | `"491527954328"`                                               |
 | `fakeit_BitcoinAddress`                  | Bitcoin address                                       | `"1BoatSLRHtKNngkdXEeobR76b53LETtpyT"`                         |
-| `fakeit_BitcoinPrivateKey`               | Bitcoin private key                                   | `"5HueCGU8rMjxEXxiPuD5BDuG6o5xjA7QkbPp"`                       |
+| `fakeit_BitcoinPrivateKey`               | Bitcoin private key                                   | `"5JMZxkQX2PgaasaHc8wnWLNdMu7rxeU7xS64ev7RWNinacicPfm"`        |
-| `fakeit_BankName`                        | Bank name                                             | `"Wells Fargo"`                                                |
+| `fakeit_BankName`                        | Bank name                                             | `"Toronto Dominion Bank"`                                      |
 | `fakeit_BankType`                        | Bank type                                             | `"Investment Bank"`                                            |
 
 ### Finance
@@ -620,17 +649,17 @@ These functions are powered by [gofakeit](https://github.com/brianvoe/gofakeit)
 
 ### Company
 
-| Function               | Description    | Example Output                             |
+| Function               | Description    | Example Output         |
-| ---------------------- | -------------- | ------------------------------------------ |
+| ---------------------- | -------------- | ---------------------- |
-| `fakeit_BS`            | Business speak | `"front-end"`                              |
+| `fakeit_BS`            | Business speak | `"front-end"`          |
-| `fakeit_Blurb`         | Company blurb  | `"word"`                                   |
+| `fakeit_Blurb`         | Company blurb  | `"Teamwork"`           |
-| `fakeit_BuzzWord`      | Buzzword       | `"disintermediate"`                        |
+| `fakeit_BuzzWord`      | Buzzword       | `"disintermediate"`    |
-| `fakeit_Company`       | Company name   | `"Moen, Pagac and Wuckert"`                |
+| `fakeit_Company`       | Company name   | `"TransparaGov"`       |
-| `fakeit_CompanySuffix` | Company suffix | `"Inc"`                                    |
+| `fakeit_CompanySuffix` | Company suffix | `"Inc"`                |
-| `fakeit_JobDescriptor` | Job descriptor | `"Central"`                                |
+| `fakeit_JobDescriptor` | Job descriptor | `"Central"`            |
-| `fakeit_JobLevel`      | Job level      | `"Assurance"`                              |
+| `fakeit_JobLevel`      | Job level      | `"Assurance"`          |
-| `fakeit_JobTitle`      | Job title      | `"Director"`                               |
+| `fakeit_JobTitle`      | Job title      | `"Director"`           |
-| `fakeit_Slogan`        | Company slogan | `"Universal seamless Focus, interactive."` |
+| `fakeit_Slogan`        | Company slogan | `"Made of styrofoam."` |
 
 ### Hacker
 
@@ -695,9 +724,9 @@ These functions are powered by [gofakeit](https://github.com/brianvoe/gofakeit)
 | `fakeit_EmojiTools`       | Tools emoji                                    | `"🔧"`                                                 |
 | `fakeit_EmojiWeather`     | Weather emoji                                  | `"☀️"`                                                 |
 | `fakeit_EmojiJob`         | Job emoji                                      | `"👨‍💻"`                                                 |
-| `fakeit_EmojiPerson`      | Person emoji                                   | `"👤"`                                                 |
+| `fakeit_EmojiPerson`      | Person emoji                                   | `"🧓"`                                                 |
-| `fakeit_EmojiGesture`     | Gesture emoji                                  | `"🙌"`                                                 |
+| `fakeit_EmojiGesture`     | Gesture emoji                                  | `"🤦‍♀️"`                                                 |
-| `fakeit_EmojiCostume`     | Costume emoji                                  | `"🎃"`                                                 |
+| `fakeit_EmojiCostume`     | Costume emoji                                  | `"🧞"`                                                 |
 | `fakeit_EmojiSentence`    | Emoji sentence with random emojis interspersed | `"Weekends reserve time for 🖼️ Disc 🏨 golf and day."` |
 
 ### Language
@@ -706,31 +735,35 @@ These functions are powered by [gofakeit](https://github.com/brianvoe/gofakeit)
 | ----------------------------- | --------------------- | -------------- |
 | `fakeit_Language`             | Language              | `"English"`    |
 | `fakeit_LanguageAbbreviation` | Language abbreviation | `"en"`         |
+| `fakeit_LanguageBCP`          | BCP language tag      | `"en-US"`      |
 | `fakeit_ProgrammingLanguage`  | Programming language  | `"Go"`         |
 
 ### Number
 
-| Function                                        | Description                         | Example                                    |
+| Function                                        | Description                         | Example                                      |
-| ----------------------------------------------- | ----------------------------------- | ------------------------------------------ |
+| ----------------------------------------------- | ----------------------------------- | -------------------------------------------- |
-| `fakeit_Number(min int, max int)`               | Random number in range              | `{{ fakeit_Number 1 100 }}` → `42`         |
+| `fakeit_Number(min int, max int)`               | Random number in range              | `{{ fakeit_Number 1 100 }}` → `42`           |
-| `fakeit_Int`                                    | Random int                          | `{{ fakeit_Int }}`                         |
+| `fakeit_Int`                                    | Random int                          | `{{ fakeit_Int }}`                           |
-| `fakeit_IntN(n int)`                            | Random int from 0 to n              | `{{ fakeit_IntN 100 }}`                    |
+| `fakeit_IntN(n int)`                            | Random int in `[0, n)`              | `{{ fakeit_IntN 100 }}`                      |
-| `fakeit_Int8`                                   | Random int8                         | `{{ fakeit_Int8 }}`                        |
+| `fakeit_Int8`                                   | Random int8                         | `{{ fakeit_Int8 }}`                          |
-| `fakeit_Int16`                                  | Random int16                        | `{{ fakeit_Int16 }}`                       |
+| `fakeit_Int16`                                  | Random int16                        | `{{ fakeit_Int16 }}`                         |
-| `fakeit_Int32`                                  | Random int32                        | `{{ fakeit_Int32 }}`                       |
+| `fakeit_Int32`                                  | Random int32                        | `{{ fakeit_Int32 }}`                         |
-| `fakeit_Int64`                                  | Random int64                        | `{{ fakeit_Int64 }}`                       |
+| `fakeit_Int64`                                  | Random int64                        | `{{ fakeit_Int64 }}`                         |
-| `fakeit_Uint`                                   | Random uint                         | `{{ fakeit_Uint }}`                        |
+| `fakeit_IntRange(min int, max int)`             | Random int in range                 | `{{ fakeit_IntRange -10 10 }}`               |
-| `fakeit_UintN(n uint)`                          | Random uint from 0 to n             | `{{ fakeit_UintN 100 }}`                   |
+| `fakeit_Uint`                                   | Random uint                         | `{{ fakeit_Uint }}`                          |
-| `fakeit_Uint8`                                  | Random uint8                        | `{{ fakeit_Uint8 }}`                       |
+| `fakeit_UintN(n uint)`                          | Random uint in `[0, n)`             | `{{ fakeit_UintN 100 }}`                     |
-| `fakeit_Uint16`                                 | Random uint16                       | `{{ fakeit_Uint16 }}`                      |
+| `fakeit_Uint8`                                  | Random uint8                        | `{{ fakeit_Uint8 }}`                         |
-| `fakeit_Uint32`                                 | Random uint32                       | `{{ fakeit_Uint32 }}`                      |
+| `fakeit_Uint16`                                 | Random uint16                       | `{{ fakeit_Uint16 }}`                        |
-| `fakeit_Uint64`                                 | Random uint64                       | `{{ fakeit_Uint64 }}`                      |
+| `fakeit_Uint32`                                 | Random uint32                       | `{{ fakeit_Uint32 }}`                        |
-| `fakeit_Float32`                                | Random float32                      | `{{ fakeit_Float32 }}`                     |
+| `fakeit_Uint64`                                 | Random uint64                       | `{{ fakeit_Uint64 }}`                        |
-| `fakeit_Float32Range(min float32, max float32)` | Random float32 in range             | `{{ fakeit_Float32Range 0 100 }}`          |
+| `fakeit_UintRange(min uint, max uint)`          | Random uint in range                | `{{ fakeit_UintRange 10 100 }}`              |
-| `fakeit_Float64`                                | Random float64                      | `{{ fakeit_Float64 }}`                     |
+| `fakeit_Float32`                                | Random float32                      | `{{ fakeit_Float32 }}`                       |
-| `fakeit_Float64Range(min float64, max float64)` | Random float64 in range             | `{{ fakeit_Float64Range 0 100 }}`          |
+| `fakeit_Float32Range(min float32, max float32)` | Random float32 in range             | `{{ fakeit_Float32Range 0 100 }}`            |
-| `fakeit_RandomInt(slice []int)`                 | Random int from slice               | `{{ fakeit_RandomInt (slice_Int 1 2 3) }}` |
+| `fakeit_Float64`                                | Random float64                      | `{{ fakeit_Float64 }}`                       |
-| `fakeit_HexUint(bits int)`                      | Random hex uint with specified bits | `{{ fakeit_HexUint 8 }}` → `"0xff"`        |
+| `fakeit_Float64Range(min float64, max float64)` | Random float64 in range             | `{{ fakeit_Float64Range 0 100 }}`            |
+| `fakeit_RandomInt(slice []int)`                 | Random int from slice               | `{{ fakeit_RandomInt (slice_Int 1 2 3) }}`   |
+| `fakeit_RandomUint(slice []uint)`               | Random uint from slice              | `{{ fakeit_RandomUint (slice_Uint 1 2 3) }}` |
+| `fakeit_HexUint(bits int)`                      | Random hex uint with specified bits | `{{ fakeit_HexUint 8 }}` → `"0xff"`          |
 
 ### String
 
@@ -740,6 +773,7 @@ These functions are powered by [gofakeit](https://github.com/brianvoe/gofakeit)
 | `fakeit_DigitN(n uint)`               | Generate `n` random digits      | `{{ fakeit_DigitN 5 }}` → `"71364"`                             |
 | `fakeit_Letter`                       | Single random letter            | `"g"`                                                           |
 | `fakeit_LetterN(n uint)`              | Generate `n` random letters     | `{{ fakeit_LetterN 10 }}` → `"gbRMaRxHki"`                      |
+| `fakeit_Vowel`                        | Single lowercase vowel          | `"a"`                                                           |
 | `fakeit_Lexify(pattern string)`       | Replace `?` with random letters | `{{ fakeit_Lexify "?????@??????.com" }}` → `"billy@mister.com"` |
 | `fakeit_Numerify(pattern string)`     | Replace `#` with random digits  | `{{ fakeit_Numerify "(###)###-####" }}` → `"(555)867-5309"`     |
 | `fakeit_RandomString(slice []string)` | Random string from slice        | `{{ fakeit_RandomString (slice_Str "a" "b" "c") }}`             |
@@ -754,26 +788,26 @@ These functions are powered by [gofakeit](https://github.com/brianvoe/gofakeit)
 
 ### Minecraft
 
-| Function                          | Description       | Example Output   |
+| Function                          | Description       | Example Output      |
-| --------------------------------- | ----------------- | ---------------- |
+| --------------------------------- | ----------------- | ------------------- |
-| `fakeit_MinecraftOre`             | Minecraft ore     | `"coal"`         |
+| `fakeit_MinecraftOre`             | Minecraft ore     | `"coal"`            |
-| `fakeit_MinecraftWood`            | Minecraft wood    | `"oak"`          |
+| `fakeit_MinecraftWood`            | Minecraft wood    | `"oak"`             |
-| `fakeit_MinecraftArmorTier`       | Armor tier        | `"iron"`         |
+| `fakeit_MinecraftArmorTier`       | Armor tier        | `"iron"`            |
-| `fakeit_MinecraftArmorPart`       | Armor part        | `"helmet"`       |
+| `fakeit_MinecraftArmorPart`       | Armor part        | `"helmet"`          |
-| `fakeit_MinecraftWeapon`          | Minecraft weapon  | `"bow"`          |
+| `fakeit_MinecraftWeapon`          | Minecraft weapon  | `"bow"`             |
-| `fakeit_MinecraftTool`            | Minecraft tool    | `"shovel"`       |
+| `fakeit_MinecraftTool`            | Minecraft tool    | `"shovel"`          |
-| `fakeit_MinecraftDye`             | Minecraft dye     | `"white"`        |
+| `fakeit_MinecraftDye`             | Minecraft dye     | `"white"`           |
-| `fakeit_MinecraftFood`            | Minecraft food    | `"apple"`        |
+| `fakeit_MinecraftFood`            | Minecraft food    | `"apple"`           |
-| `fakeit_MinecraftAnimal`          | Minecraft animal  | `"chicken"`      |
+| `fakeit_MinecraftAnimal`          | Minecraft animal  | `"chicken"`         |
-| `fakeit_MinecraftVillagerJob`     | Villager job      | `"farmer"`       |
+| `fakeit_MinecraftVillagerJob`     | Villager job      | `"farmer"`          |
-| `fakeit_MinecraftVillagerStation` | Villager station  | `"furnace"`      |
+| `fakeit_MinecraftVillagerStation` | Villager station  | `"stonecutter"`     |
-| `fakeit_MinecraftVillagerLevel`   | Villager level    | `"master"`       |
+| `fakeit_MinecraftVillagerLevel`   | Villager level    | `"master"`          |
-| `fakeit_MinecraftMobPassive`      | Passive mob       | `"cow"`          |
+| `fakeit_MinecraftMobPassive`      | Passive mob       | `"cow"`             |
-| `fakeit_MinecraftMobNeutral`      | Neutral mob       | `"bee"`          |
+| `fakeit_MinecraftMobNeutral`      | Neutral mob       | `"bee"`             |
-| `fakeit_MinecraftMobHostile`      | Hostile mob       | `"spider"`       |
+| `fakeit_MinecraftMobHostile`      | Hostile mob       | `"wither skeleton"` |
-| `fakeit_MinecraftMobBoss`         | Boss mob          | `"ender dragon"` |
+| `fakeit_MinecraftMobBoss`         | Boss mob          | `"ender dragon"`    |
-| `fakeit_MinecraftBiome`           | Minecraft biome   | `"forest"`       |
+| `fakeit_MinecraftBiome`           | Minecraft biome   | `"forest"`          |
-| `fakeit_MinecraftWeather`         | Minecraft weather | `"rain"`         |
+| `fakeit_MinecraftWeather`         | Minecraft weather | `"rain"`            |
 
 ### Book
 
@@ -792,26 +826,28 @@ These functions are powered by [gofakeit](https://github.com/brianvoe/gofakeit)
 
 ### Error
 
-| Function                 | Description       | Example Output                     |
+| Function                 | Description       | Example Output                                  |
-| ------------------------ | ----------------- | ---------------------------------- |
+| ------------------------ | ----------------- | ----------------------------------------------- |
-| `fakeit_Error`           | Random error      | `"connection refused"`             |
+| `fakeit_Error`           | Random error      | `"variable assigned before declaration"`        |
-| `fakeit_ErrorDatabase`   | Database error    | `"database connection failed"`     |
+| `fakeit_ErrorObject`     | Error object      | `"protocol"`                                    |
-| `fakeit_ErrorGRPC`       | gRPC error        | `"rpc error: code = Unavailable"`  |
+| `fakeit_ErrorDatabase`   | Database error    | `"destination pointer is nil"`                  |
-| `fakeit_ErrorHTTP`       | HTTP error        | `"HTTP 500 Internal Server Error"` |
+| `fakeit_ErrorGRPC`       | gRPC error        | `"connection refused"`                          |
-| `fakeit_ErrorHTTPClient` | HTTP client error | `"HTTP 404 Not Found"`             |
+| `fakeit_ErrorHTTP`       | HTTP error        | `"wrote more than the declared Content-Length"` |
-| `fakeit_ErrorHTTPServer` | HTTP server error | `"HTTP 503 Service Unavailable"`   |
+| `fakeit_ErrorHTTPClient` | HTTP client error | `"expectation failed"`                          |
-| `fakeit_ErrorRuntime`    | Runtime error     | `"panic: runtime error"`           |
+| `fakeit_ErrorHTTPServer` | HTTP server error | `"not extended"`                                |
+| `fakeit_ErrorRuntime`    | Runtime error     | `"expected 2 arguments, got 3"`                 |
+| `fakeit_ErrorValidation` | Validation error  | `"missing required field"`                      |
 
 ### School
 
-| Function        | Description | Example Output         |
+| Function        | Description | Example Output               |
-| --------------- | ----------- | ---------------------- |
+| --------------- | ----------- | ---------------------------- |
-| `fakeit_School` | School name | `"Harvard University"` |
+| `fakeit_School` | School name | `"Hillside Private Academy"` |
 
 ### Song
 
-| Function            | Description | Example Output        |
+| Function            | Description | Example Output           |
-| ------------------- | ----------- | --------------------- |
+| ------------------- | ----------- | ------------------------ |
-| `fakeit_SongName`   | Song name   | `"Bohemian Rhapsody"` |
+| `fakeit_SongName`   | Song name   | `"What Was I Made For?"` |
-| `fakeit_SongArtist` | Song artist | `"Queen"`             |
+| `fakeit_SongArtist` | Song artist | `"Queen"`                |
-| `fakeit_SongGenre`  | Song genre  | `"Rock"`              |
+| `fakeit_SongGenre`  | Song genre  | `"Rock"`                 |

flake.lock

@@ -0,0 +1,27 @@
+{
+  "nodes": {
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1789006805,
+        "narHash": "sha256-xB8mKMOx1IA9vTDNLmJZ6n4wCMq/cuWBBOzGCRnqxrU=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "8ce4ef6cb6f871616146b9fe26d2a5ae594e94fe",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixos-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "nixpkgs": "nixpkgs"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

@@ -0,0 +1,55 @@
+{
+  description = "Sarin - high-performance HTTP load testing tool built with Go and fasthttp";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+  };
+
+  outputs = { self, nixpkgs }:
+    let
+      inherit (nixpkgs) lib;
+
+      systems = [
+        "x86_64-linux"
+        "aarch64-linux"
+        "x86_64-darwin"
+        "aarch64-darwin"
+      ];
+
+      forAllSystems = f: lib.genAttrs systems (system: f nixpkgs.legacyPackages.${system});
+
+      rev = self.rev or self.dirtyRev or "unknown";
+
+      # self.lastModifiedDate is "YYYYMMDDHHMMSS"; reshape to RFC 3339 (UTC).
+      raw = self.lastModifiedDate or "19700101000000";
+      s = i: n: lib.substring i n raw;
+      buildDate = "${s 0 4}-${s 4 2}-${s 6 2}T${s 8 2}:${s 10 2}:${s 12 2}Z";
+    in
+    {
+      packages = forAllSystems (pkgs: {
+        default = pkgs.callPackage ./nix/package.nix {
+          inherit rev buildDate;
+        };
+      });
+
+      # nix run github:aykhans/sarin/release -- <args>
+      apps = forAllSystems (pkgs: {
+        default = {
+          type = "app";
+          program = "${self.packages.${pkgs.stdenv.hostPlatform.system}.default}/bin/sarin";
+          meta.description = "High-performance HTTP load testing tool";
+        };
+      });
+
+      devShells = forAllSystems (pkgs: {
+        default = pkgs.mkShell {
+          packages = [ pkgs.go_1_27 pkgs.golangci-lint pkgs.go-task ];
+        };
+      });
+
+      # For downstream flakes: inputs.sarin.overlays.default
+      overlays.default = final: _prev: {
+        sarin = final.callPackage ./nix/package.nix { };
+      };
+    };
+}

go.mod

@@ -1,58 +1,53 @@
 module go.aykhans.me/sarin
 
-go 1.26.4
+go 1.27.1
 
 require (
-	github.com/brianvoe/gofakeit/v7 v7.15.0
+	charm.land/bubbles/v2 v2.2.1
-	github.com/charmbracelet/bubbles v1.0.0
+	charm.land/bubbletea/v2 v2.0.9
-	github.com/charmbracelet/bubbletea v1.3.10
+	charm.land/glamour/v2 v2.0.1
-	github.com/charmbracelet/glamour v1.0.0
+	charm.land/lipgloss/v2 v2.0.6
-	github.com/charmbracelet/lipgloss v1.1.1-0.20250404203927-76690c660834
+	github.com/brianvoe/gofakeit/v7 v7.17.0
 	github.com/charmbracelet/x/term v0.2.2
-	github.com/dop251/goja v0.0.0-20260603143327-1f200ca63355
+	github.com/dop251/goja v0.0.0-20260911104922-fabc3b8078ad
 	github.com/joho/godotenv v1.5.1
-	github.com/valyala/fasthttp v1.71.0
+	github.com/valyala/fasthttp v1.74.0
 	github.com/yuin/gopher-lua v1.1.2
 	go.aykhans.me/utils v1.0.7
-	go.yaml.in/yaml/v4 v4.0.0-rc.4
+	go.yaml.in/yaml/v4 v4.0.0-rc.6
-	golang.org/x/net v0.55.0
+	golang.org/x/net v0.59.0
 )
 
 require (
-	github.com/alecthomas/chroma/v2 v2.26.1 // indirect
+	github.com/alecthomas/chroma/v2 v2.27.0 // indirect
-	github.com/andybalholm/brotli v1.2.1 // indirect
-	github.com/aymanbagabas/go-osc52/v2 v2.0.1 // indirect
 	github.com/aymerick/douceur v0.2.0 // indirect
 	github.com/charmbracelet/colorprofile v0.4.3 // indirect
 	github.com/charmbracelet/harmonica v0.2.0 // indirect
-	github.com/charmbracelet/x/ansi v0.11.7 // indirect
+	github.com/charmbracelet/ultraviolet v0.0.0-20260910203606-6c9e17dc7a16 // indirect
-	github.com/charmbracelet/x/cellbuf v0.0.15 // indirect
+	github.com/charmbracelet/x/ansi v0.11.8 // indirect
-	github.com/charmbracelet/x/exp/slice v0.0.0-20260602025833-85a30b5e440a // indirect
+	github.com/charmbracelet/x/exp/slice v0.0.0-20260906004030-3986e9119cf9 // indirect
+	github.com/charmbracelet/x/termios v0.1.1 // indirect
+	github.com/charmbracelet/x/windows v0.2.2 // indirect
 	github.com/clipperhouse/displaywidth v0.11.0 // indirect
 	github.com/clipperhouse/uax29/v2 v2.7.0 // indirect
 	github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc // indirect
-	github.com/dlclark/regexp2/v2 v2.1.2 // indirect
+	github.com/dlclark/regexp2/v2 v2.8.0 // indirect
-	github.com/erikgeiser/coninput v0.0.0-20211004153227-1c3628e74d0f // indirect
 	github.com/go-sourcemap/sourcemap v2.1.4+incompatible // indirect
-	github.com/google/pprof v0.0.0-20260604005048-7023385849c0 // indirect
+	github.com/google/pprof v0.0.0-20260906184651-6331bc6350fe // indirect
 	github.com/gorilla/css v1.0.1 // indirect
-	github.com/klauspost/compress v1.18.6 // indirect
+	github.com/klauspost/compress v1.20.0 // indirect
-	github.com/lucasb-eyer/go-colorful v1.4.0 // indirect
+	github.com/lucasb-eyer/go-colorful v1.4.1 // indirect
-	github.com/mattn/go-isatty v0.0.22 // indirect
+	github.com/mattn/go-runewidth v0.0.30 // indirect
-	github.com/mattn/go-localereader v0.0.1 // indirect
-	github.com/mattn/go-runewidth v0.0.24 // indirect
 	github.com/microcosm-cc/bluemonday v1.0.27 // indirect
-	github.com/muesli/ansi v0.0.0-20230316100256-276c6243b2f6 // indirect
+	github.com/molecule-man/go-brrr v1.1.0 // indirect
 	github.com/muesli/cancelreader v0.2.2 // indirect
-	github.com/muesli/reflow v0.3.0 // indirect
-	github.com/muesli/termenv v0.16.0 // indirect
 	github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 // indirect
 	github.com/rivo/uniseg v0.4.7 // indirect
 	github.com/valyala/bytebufferpool v1.0.0 // indirect
-	github.com/xo/terminfo v0.0.0-20220910002029-abceb7e1c41e // indirect
+	github.com/xo/terminfo v1.0.0 // indirect
-	github.com/yuin/goldmark v1.8.2 // indirect
+	github.com/yuin/goldmark v1.8.6 // indirect
 	github.com/yuin/goldmark-emoji v1.0.6 // indirect
-	golang.org/x/sys v0.45.0 // indirect
+	golang.org/x/sync v0.23.0 // indirect
-	golang.org/x/term v0.43.0 // indirect
+	golang.org/x/sys v0.48.0 // indirect
-	golang.org/x/text v0.37.0 // indirect
+	golang.org/x/text v0.42.0 // indirect
 )

go.sum

@@ -1,124 +1,110 @@
-github.com/Masterminds/semver/v3 v3.2.1 h1:RN9w6+7QoMeJVGyfmbcgs28Br8cvmnucEXnY0rYXWg0=
+charm.land/bubbles/v2 v2.2.1 h1:Fq1+qm5hV6GkvzLQDhCBpXXE5tLgvh1PRriCLwSvIQU=
-github.com/Masterminds/semver/v3 v3.2.1/go.mod h1:qvl/7zhW3nngYb5+80sSMF+FG2BjYrf8m9wsX0PNOMQ=
+charm.land/bubbles/v2 v2.2.1/go.mod h1:wdMgn+sje1KNXdwFizIWjbf328fIUBxqEmJ/vYPo8yc=
+charm.land/bubbletea/v2 v2.0.9 h1:DpJCMWKgzQK8SJv4zbKKFHAI10ymWy/evClPFk0k0f8=
+charm.land/bubbletea/v2 v2.0.9/go.mod h1:2SkdgoTXluXJHOUwAoRlRXF/28vklb1rFl6GcgV1/ss=
+charm.land/glamour/v2 v2.0.1 h1:xl+r00A4aJWU0z8fgwKd9fQQ4rsphqGUzuEiXZP5n+c=
+charm.land/glamour/v2 v2.0.1/go.mod h1:jo9z8XqVKPeEFMVdvCRLGk++RyJ3CdUwgNr7EvXLw3k=
+charm.land/lipgloss/v2 v2.0.6 h1:EaGKeuA8FvF+v2BT5VmZd2LoYLaMZJXA5n34th8nCIQ=
+charm.land/lipgloss/v2 v2.0.6/go.mod h1:ipDDJNSGa1hlwDtSfW1s2/xR8Vdhbut4PXh2zEKZd0Q=
+github.com/Masterminds/semver/v3 v3.5.0 h1:kQceYJfbupGfZOKZQg0kou0DgAKhzDg2NZPAwZ/2OOE=
+github.com/Masterminds/semver/v3 v3.5.0/go.mod h1:4V+yj/TJE1HU9XfppCwVMZq3I84lprf4nC11bSS5beM=
 github.com/alecthomas/assert/v2 v2.11.0 h1:2Q9r3ki8+JYXvGsDyBXwH3LcJ+WK5D0gc5E8vS6K3D0=
 github.com/alecthomas/assert/v2 v2.11.0/go.mod h1:Bze95FyfUr7x34QZrjL+XP+0qgp/zg8yS+TtBj1WA3k=
-github.com/alecthomas/chroma/v2 v2.26.1 h1:2X21EdxGZNv5GF9mG5u+uzc02GCFyGxbcBm3Grd9A78=
+github.com/alecthomas/chroma/v2 v2.27.0 h1:FodwmyOBgJULFYmDqibcp9pvfDLWdtPRh9v/r5BXYZs=
-github.com/alecthomas/chroma/v2 v2.26.1/go.mod h1:lxhRRa9H4hPmRLOOdYga4zkQIQjq3dtrrdwQeCfu78Y=
+github.com/alecthomas/chroma/v2 v2.27.0/go.mod h1:NjJ3ciIgrqBNeIkWZ4e46nseoLDslxU1LmfCoL+wcY8=
 github.com/alecthomas/repr v0.5.2 h1:SU73FTI9D1P5UNtvseffFSGmdNci/O6RsqzeXJtP0Qs=
 github.com/alecthomas/repr v0.5.2/go.mod h1:Fr0507jx4eOXV7AlPV6AVZLYrLIuIeSOWtW57eE/O/4=
-github.com/andybalholm/brotli v1.2.1 h1:R+f5xP285VArJDRgowrfb9DqL18yVK0gKAW/F+eTWro=
+github.com/aymanbagabas/go-udiff v0.4.1 h1:OEIrQ8maEeDBXQDoGCbbTTXYJMYRCRO1fnodZ12Gv5o=
-github.com/andybalholm/brotli v1.2.1/go.mod h1:rzTDkvFWvIrjDXZHkuS16NPggd91W3kUSvPlQ1pLaKY=
+github.com/aymanbagabas/go-udiff v0.4.1/go.mod h1:0L9PGwj20lrtmEMeyw4WKJ/TMyDtvAoK9bf2u/mNo3w=
-github.com/aymanbagabas/go-osc52/v2 v2.0.1 h1:HwpRHbFMcZLEVr42D4p7XBqjyuxQH5SMiErDT4WkJ2k=
-github.com/aymanbagabas/go-osc52/v2 v2.0.1/go.mod h1:uYgXzlJ7ZpABp8OJ+exZzJJhRNQ2ASbcXHWsFqH8hp8=
-github.com/aymanbagabas/go-udiff v0.3.1 h1:LV+qyBQ2pqe0u42ZsUEtPiCaUoqgA9gYRDs3vj1nolY=
-github.com/aymanbagabas/go-udiff v0.3.1/go.mod h1:G0fsKmG+P6ylD0r6N/KgQD/nWzgfnl8ZBcNLgcbrw8E=
 github.com/aymerick/douceur v0.2.0 h1:Mv+mAeH1Q+n9Fr+oyamOlAkUNPWPlA8PPGR0QAaYuPk=
 github.com/aymerick/douceur v0.2.0/go.mod h1:wlT5vV2O3h55X9m7iVYN0TBM0NH/MmbLnd30/FjWUq4=
-github.com/brianvoe/gofakeit/v7 v7.15.0 h1:kGLYAWN8tnmxq2PelKVK6zwpM7kMxdz9SGPH31mFkNs=
+github.com/brianvoe/gofakeit/v7 v7.17.0 h1:usvHa73vmAjC1JmX4dpZAm1eQkR0riXaxvilScRTFb0=
-github.com/brianvoe/gofakeit/v7 v7.15.0/go.mod h1:QXuPeBw164PJCzCUZVmgpgHJ3Llj49jSLVkKPMtxtxA=
+github.com/brianvoe/gofakeit/v7 v7.17.0/go.mod h1:QXuPeBw164PJCzCUZVmgpgHJ3Llj49jSLVkKPMtxtxA=
-github.com/charmbracelet/bubbles v1.0.0 h1:12J8/ak/uCZEMQ6KU7pcfwceyjLlWsDLAxB5fXonfvc=
-github.com/charmbracelet/bubbles v1.0.0/go.mod h1:9d/Zd5GdnauMI5ivUIVisuEm3ave1XwXtD1ckyV6r3E=
-github.com/charmbracelet/bubbletea v1.3.10 h1:otUDHWMMzQSB0Pkc87rm691KZ3SWa4KUlvF9nRvCICw=
-github.com/charmbracelet/bubbletea v1.3.10/go.mod h1:ORQfo0fk8U+po9VaNvnV95UPWA1BitP1E0N6xJPlHr4=
 github.com/charmbracelet/colorprofile v0.4.3 h1:QPa1IWkYI+AOB+fE+mg/5/4HRMZcaXex9t5KX76i20Q=
 github.com/charmbracelet/colorprofile v0.4.3/go.mod h1:/zT4BhpD5aGFpqQQqw7a+VtHCzu+zrQtt1zhMt9mR4Q=
-github.com/charmbracelet/glamour v1.0.0 h1:AWMLOVFHTsysl4WV8T8QgkQ0s/ZNZo7CiE4WKhk8l08=
-github.com/charmbracelet/glamour v1.0.0/go.mod h1:DSdohgOBkMr2ZQNhw4LZxSGpx3SvpeujNoXrQyH2hxo=
 github.com/charmbracelet/harmonica v0.2.0 h1:8NxJWRWg/bzKqqEaaeFNipOu77YR5t8aSwG4pgaUBiQ=
 github.com/charmbracelet/harmonica v0.2.0/go.mod h1:KSri/1RMQOZLbw7AHqgcBycp8pgJnQMYYT8QZRqZ1Ao=
-github.com/charmbracelet/lipgloss v1.1.1-0.20250404203927-76690c660834 h1:ZR7e0ro+SZZiIZD7msJyA+NjkCNNavuiPBLgerbOziE=
+github.com/charmbracelet/ultraviolet v0.0.0-20260910203606-6c9e17dc7a16 h1:/hSCZO1puetbGd2JikHKN0nAcb2mFevzxJElFoduhaw=
-github.com/charmbracelet/lipgloss v1.1.1-0.20250404203927-76690c660834/go.mod h1:aKC/t2arECF6rNOnaKaVU6y4t4ZeHQzqfxedE/VkVhA=
+github.com/charmbracelet/ultraviolet v0.0.0-20260910203606-6c9e17dc7a16/go.mod h1:JFvmQPZh3uAu7PpSZU91bcR0BrIy24HhW+0EsW1uGxE=
-github.com/charmbracelet/x/ansi v0.11.7 h1:kzv1kJvjg2S3r9KHo8hDdHFQLEqn4RBCb39dAYC84jI=
+github.com/charmbracelet/x/ansi v0.11.8 h1:JMFwp0CgDC2+jcOB162HH5k7I3FVbgFSMMYg7dSPBQQ=
-github.com/charmbracelet/x/ansi v0.11.7/go.mod h1:9qGpnAVYz+8ACONkZBUWPtL7lulP9No6p1epAihUZwQ=
+github.com/charmbracelet/x/ansi v0.11.8/go.mod h1:ZNN+3mXny/516oTQPLMPIBeSINvNJJQ8uQXDgbeJxY0=
-github.com/charmbracelet/x/cellbuf v0.0.15 h1:ur3pZy0o6z/R7EylET877CBxaiE1Sp1GMxoFPAIztPI=
+github.com/charmbracelet/x/exp/golden v0.0.0-20250806222409-83e3a29d542f h1:pk6gmGpCE7F3FcjaOEKYriCvpmIN4+6OS/RD0vm4uIA=
-github.com/charmbracelet/x/cellbuf v0.0.15/go.mod h1:J1YVbR7MUuEGIFPCaaZ96KDl5NoS0DAWkskup+mOY+Q=
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-github.com/charmbracelet/x/exp/golden v0.0.0-20241011142426-46044092ad91 h1:payRxjMjKgx2PaCWLZ4p3ro9y97+TVLZNaRZgJwSVDQ=
+github.com/charmbracelet/x/exp/slice v0.0.0-20260906004030-3986e9119cf9 h1:zW96vcZ3zDetccerbN7sS/sCydOE/l/9S+C94pozsaU=
-github.com/charmbracelet/x/exp/golden v0.0.0-20241011142426-46044092ad91/go.mod h1:wDlXFlCrmJ8J+swcL/MnGUuYnqgQdW9rhSD61oNMb6U=
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-github.com/charmbracelet/x/exp/slice v0.0.0-20260602025833-85a30b5e440a h1:wjp4RGuKcbK244BiURmgle3N9HMT1ParMh96omH6Lj4=
-github.com/charmbracelet/x/exp/slice v0.0.0-20260602025833-85a30b5e440a/go.mod h1:vqEfX6xzqW1pKKZUUiFOKg0OQ7bCh54Q2vR/tserrRA=
 github.com/charmbracelet/x/term v0.2.2 h1:xVRT/S2ZcKdhhOuSP4t5cLi5o+JxklsoEObBSgfgZRk=
 github.com/charmbracelet/x/term v0.2.2/go.mod h1:kF8CY5RddLWrsgVwpw4kAa6TESp6EB5y3uxGLeCqzAI=
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+github.com/charmbracelet/x/termios v0.1.1/go.mod h1:rB7fnv1TgOPOyyKRJ9o+AsTU/vK5WHJ2ivHeut/Pcwo=
+github.com/charmbracelet/x/windows v0.2.2 h1:IofanmuvaxnKHuV04sC0eBy/smG6kIKrWG2/jYn2GuM=
+github.com/charmbracelet/x/windows v0.2.2/go.mod h1:/8XtdKZzedat74NQFn0NGlGL4soHB0YQZrETF96h75k=
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 github.com/clipperhouse/displaywidth v0.11.0/go.mod h1:bkrFNkf81G8HyVqmKGxsPufD3JhNl3dSqnGhOoSD/o0=
 github.com/clipperhouse/uax29/v2 v2.7.0 h1:+gs4oBZ2gPfVrKPthwbMzWZDaAFPGYK72F0NJv2v7Vk=
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 github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc h1:U9qPSI2PIWSS1VwoXQT9A3Wy9MM3WgvqSxFWenqJduM=
 github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
-github.com/dlclark/regexp2/v2 v2.1.2 h1:RJjAeD/h91npDhTG4rMD4+gzGVnLT32qQy/q/ECbyUs=
+github.com/dlclark/regexp2/v2 v2.8.0 h1:CekDhPLGfm+GAJmPVFIG+5dqMIQPkyHJll7BbdneDfw=
-github.com/dlclark/regexp2/v2 v2.1.2/go.mod h1:avUrQvPaLz2DrFNHJF0taWAFFX2C1GMSSoeiqFjcBmU=
+github.com/dlclark/regexp2/v2 v2.8.0/go.mod h1:avUrQvPaLz2DrFNHJF0taWAFFX2C1GMSSoeiqFjcBmU=
-github.com/dop251/goja v0.0.0-20260603143327-1f200ca63355 h1:QCZbLvvKw3vwkMubwAHHBIecVHyLGfyty0yf5+cx5As=
+github.com/dop251/goja v0.0.0-20260911104922-fabc3b8078ad h1:5gT9hQ9h8CplLZfAGgFMcoLqQS6I9T2sZwQOCXy8/3s=
-github.com/dop251/goja v0.0.0-20260603143327-1f200ca63355/go.mod h1:YkABBhNI1qP6/NuyyPL5QqJ4L28ax4m+WAywAWr9fJk=
+github.com/dop251/goja v0.0.0-20260911104922-fabc3b8078ad/go.mod h1:u8yZRUavu+N4EnFFy6J5fVtjE7lEcZ2YyV2GcBXY9c8=
-github.com/erikgeiser/coninput v0.0.0-20211004153227-1c3628e74d0f h1:Y/CXytFA4m6baUTXGLOoWe4PQhGxaX0KpnayAqC48p4=
-github.com/erikgeiser/coninput v0.0.0-20211004153227-1c3628e74d0f/go.mod h1:vw97MGsxSvLiUE2X8qFplwetxpGLQrlU1Q9AUEIzCaM=
 github.com/go-sourcemap/sourcemap v2.1.4+incompatible h1:a+iTbH5auLKxaNwQFg0B+TCYl6lbukKPc7b5x0n1s6Q=
 github.com/go-sourcemap/sourcemap v2.1.4+incompatible/go.mod h1:F8jJfvm2KbVjc5NqelyYJmf/v5J0dwNLS2mL4sNA1Jg=
 github.com/goccy/go-yaml v1.19.2 h1:PmFC1S6h8ljIz6gMRBopkjP1TVT7xuwrButHID66PoM=
 github.com/goccy/go-yaml v1.19.2/go.mod h1:XBurs7gK8ATbW4ZPGKgcbrY1Br56PdM69F7LkFRi1kA=
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-github.com/google/pprof v0.0.0-20260604005048-7023385849c0/go.mod h1:MxpfABSjhmINe3F1It9d+8exIHFvUqtLIRCdOGNXqiI=
+github.com/google/pprof v0.0.0-20260906184651-6331bc6350fe/go.mod h1:jl5iWTm0/hd5PjEYEOuwAJ57L/CibdZfrqZ5XA5GrCk=
 github.com/gorilla/css v1.0.1 h1:ntNaBIghp6JmvWnxbZKANoLyuXTPZ4cAMlo6RyhlbO8=
 github.com/gorilla/css v1.0.1/go.mod h1:BvnYkspnSzMmwRK+b8/xgNPLiIuNZr6vbZBTPQ2A3b0=
 github.com/hexops/gotextdiff v1.0.3 h1:gitA9+qJrrTCsiCl7+kh75nPqQt1cx4ZkudSTLoUqJM=
 github.com/hexops/gotextdiff v1.0.3/go.mod h1:pSWU5MAI3yDq+fZBTazCSJysOMbxWL1BSow5/V2vxeg=
 github.com/joho/godotenv v1.5.1 h1:7eLL/+HRGLY0ldzfGMeQkb7vMd0as4CfYvUVzLqw0N0=
 github.com/joho/godotenv v1.5.1/go.mod h1:f4LDr5Voq0i2e/R5DDNOoa2zzDfwtkZa6DnEwAbqwq4=
-github.com/klauspost/compress v1.18.6 h1:2jupLlAwFm95+YDR+NwD2MEfFO9d4z4Prjl1XXDjuao=
+github.com/klauspost/compress v1.20.0 h1:a3C1ke2ohxFymNlb2HWAHjDeKCI90scRskErZkR0ezA=
-github.com/klauspost/compress v1.18.6/go.mod h1:cwPg85FWrGar70rWktvGQj8/hthj3wpl0PGDogxkrSQ=
+github.com/klauspost/compress v1.20.0/go.mod h1:LUdAzn7YLVvxLpc7y3V1m40wESHTgc1422pwwBSKYuI=
-github.com/lucasb-eyer/go-colorful v1.4.0 h1:UtrWVfLdarDgc44HcS7pYloGHJUjHV/4FwW4TvVgFr4=
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 github.com/microcosm-cc/bluemonday v1.0.27/go.mod h1:jFi9vgW+H7c3V0lb6nR74Ib/DIB5OBs92Dimizgw2cA=
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 github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
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 github.com/rivo/uniseg v0.4.7/go.mod h1:FN3SvrM+Zdj16jyLfmOkMNblXMcoc8DfTHruCPUcx88=
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 github.com/stretchr/testify v1.11.1/go.mod h1:wZwfW3scLgRK+23gO65QZefKpKQRnfz6sD981Nm4B6U=
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 github.com/valyala/bytebufferpool v1.0.0/go.mod h1:6bBcMArwyJ5K/AmCkWv1jt77kVWyCJ6HpOuEn7z0Csc=
-github.com/valyala/fasthttp v1.71.0 h1:tepR7H+Guh9VUqxxcPggYi8R3lGUu2Rsdh+z7/FCY3k=
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-github.com/xyproto/randomstring v1.0.5 h1:YtlWPoRdgMu3NZtP45drfy1GKoojuR7hmRcnhZqKjWU=
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-github.com/yuin/goldmark v1.8.2 h1:kEGpgqJXdgbkhcOgBxkC0X0PmoPG1ZyoZ117rDVp4zE=
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 go.aykhans.me/utils v1.0.7/go.mod h1:0Jz8GlZLN35cCHLOLx39sazWwEe33bF6SYlSeqzEXoI=
-go.yaml.in/yaml/v4 v4.0.0-rc.4 h1:UP4+v6fFrBIb1l934bDl//mmnoIZEDK0idg1+AIvX5U=
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 gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

internal/config/bytesize.go

@@ -0,0 +1,40 @@
+package config
+
+import (
+	"flag"
+	"fmt"
+
+	"go.aykhans.me/sarin/internal/types"
+	"go.yaml.in/yaml/v4"
+)
+
+var (
+	_ flag.Value       = (*byteSize)(nil)
+	_ yaml.Unmarshaler = (*byteSize)(nil)
+)
+
+// byteSize is a size in bytes that reads and prints unit suffixes such as 10MiB.
+type byteSize uint64
+
+func (size byteSize) String() string {
+	return types.FormatByteSize(uint64(size))
+}
+
+// Set fills the size from a command line value.
+func (size *byteSize) Set(value string) error {
+	parsed, err := types.ParseByteSize(value)
+	if err != nil {
+		return err
+	}
+	*size = byteSize(parsed)
+	return nil
+}
+
+// UnmarshalYAML reads the raw scalar so a size parses the same way here as on the command line.
+func (size *byteSize) UnmarshalYAML(node *yaml.Node) error {
+	if node.Kind != yaml.ScalarNode {
+		return fmt.Errorf("expected a size, but got %s", yamlNodeName(node))
+	}
+
+	return size.Set(node.Value)
+}

internal/config/cli.go

@@ -20,30 +20,33 @@ Simple usage:
 
 Flags:
   General Config:
-    -h, -help                     Help for sarin
+    -h, -help                         Help for sarin
-    -v, -version                  Version for sarin
+    -v, -version                      Version for sarin
-    -s, -show-config   bool       Show the final config after parsing all sources (default %v)
+    -s, -show-config       bool       Show the final config after parsing all sources (default %v)
-    -f, -config-file   string     Path to the config file (local file / http URL)
+    -f, -config-file       []string   Path to the config file (local file / http URL)
-    -c, -concurrency   uint       Number of concurrent requests (default %d)
+    -c, -concurrency       uint       Number of concurrent requests (default %d)
-    -r, -requests      uint       Number of total requests
+    -r, -requests          uint       Number of total requests
-    -d, -duration      time       Maximum duration for the test (e.g. 30s, 1m, 5h)
+    -d, -duration          time       Maximum duration for the test (e.g. 30s, 1m, 5h)
-    -q, -quiet         bool       Hide the progress bar and runtime logs (default %v)
+    -l, -log-level         string     Runtime log levels to emit, comma-separated (possible values: info, error) (default %s)
-    -o, -output        string     Output format (possible values: table, json, yaml, none) (default '%v')
+    -w, -log-file          string     Write runtime logs to this file instead of the terminal/stderr
-    -z, -dry-run       bool       Run without sending requests (default %v)
+    -p, -progress          string     Progress display (possible values: bar, none) (default '%v')
+    -o, -output            string     Output format (possible values: table, json, yaml, none) (default '%v')
+    -z, -dry-run           bool       Run without sending requests (default %v)
 
   Request Config:
-    -U, -url           string     Target URL for the request
+    -U, -url               string     Target URL for the request
-    -M, -method        []string   HTTP method for the request (default %s)
+    -M, -method            []string   HTTP method for the request (default %s)
-    -B, -body          []string   Body for the request (e.g. "body text")
+    -B, -body              []string   Body for the request (e.g. "body text")
-    -P, -param         []string   URL parameter for the request (e.g. "key1=value1")
+    -P, -param             []string   URL parameter for the request (e.g. "key1=value1")
-    -H, -header        []string   Header for the request (e.g. "key1: value1")
+    -H, -header            []string   Header for the request (e.g. "key1: value1")
-    -C, -cookie        []string   Cookie for the request (e.g. "key1=value1")
+    -C, -cookie            []string   Cookie for the request (e.g. "key1=value1")
-    -X, -proxy         []string   Proxy for the request (e.g. "http://proxy.example.com:8080")
+    -X, -proxy             []string   Proxy for the request (e.g. "http://proxy.example.com:8080")
-    -V, -values        []string   List of values for templating (e.g. "key1=value1")
+    -V, -values            []string   List of values for templating (e.g. "key1=value1")
-    -T, -timeout       time       Timeout for the request (e.g. 400ms, 3s, 1m10s) (default %v)
+    -T, -timeout           time       Timeout for the request (e.g. 400ms, 3s, 1m10s) (default %v)
-    -I, -insecure      bool       Skip SSL/TLS certificate verification (default %v)
+    -S, -max-response-body size       Largest response body to read (e.g. 10MiB, 2MB), 0 for no limit (default %s)
-        -lua           []string   Lua script for request transformation (inline or @file/@url)
+    -I, -insecure          bool       Skip SSL/TLS certificate verification (default %v)
-        -js            []string   JavaScript script for request transformation (inline or @file/@url)`
+        -lua               []string   Lua script for request transformation (inline or @file/@url)
+        -js                []string   JavaScript script for request transformation (inline or @file/@url)`
 
 var _ IParser = ConfigCLIParser{}
 
@@ -88,23 +91,26 @@ func (parser ConfigCLIParser) Parse() (*Config, error) {
 		concurrency  uint
 		requestCount uint64
 		duration     time.Duration
-		quiet        bool
+		logLevel     string
+		logFile      string
+		progress     string
 		output       string
 		dryRun       bool
 
 		// Request config
-		urlInput   string
+		urlInput        string
-		methods    = stringSliceArg{}
+		methods         = stringSliceArg{}
-		bodies     = stringSliceArg{}
+		bodies          = stringSliceArg{}
-		params     = stringSliceArg{}
+		params          = stringSliceArg{}
-		headers    = stringSliceArg{}
+		headers         = stringSliceArg{}
-		cookies    = stringSliceArg{}
+		cookies         = stringSliceArg{}
-		proxies    = stringSliceArg{}
+		proxies         = stringSliceArg{}
-		values     = stringSliceArg{}
+		values          = stringSliceArg{}
-		timeout    time.Duration
+		timeout         time.Duration
-		insecure   bool
+		maxResponseBody byteSize
-		luaScripts = stringSliceArg{}
+		insecure        bool
-		jsScripts  = stringSliceArg{}
+		luaScripts      = stringSliceArg{}
+		jsScripts       = stringSliceArg{}
 	)
 
 	{
@@ -127,8 +133,14 @@ func (parser ConfigCLIParser) Parse() (*Config, error) {
 		flagSet.DurationVar(&duration, "duration", 0, "Maximum duration for the test")
 		flagSet.DurationVar(&duration, "d", 0, "Maximum duration for the test")
 
-		flagSet.BoolVar(&quiet, "quiet", false, "Hide the progress bar and runtime logs")
+		flagSet.StringVar(&logLevel, "log-level", "", "Runtime log levels to emit, comma-separated (possible values: info, error)")
-		flagSet.BoolVar(&quiet, "q", false, "Hide the progress bar and runtime logs")
+		flagSet.StringVar(&logLevel, "l", "", "Runtime log levels to emit, comma-separated (possible values: info, error)")
+
+		flagSet.StringVar(&logFile, "log-file", "", "Write runtime logs to this file instead of the terminal/stderr")
+		flagSet.StringVar(&logFile, "w", "", "Write runtime logs to this file instead of the terminal/stderr")
+
+		flagSet.StringVar(&progress, "progress", "", "Progress display (possible values: bar, none)")
+		flagSet.StringVar(&progress, "p", "", "Progress display (possible values: bar, none)")
 
 		flagSet.StringVar(&output, "output", "", "Output format (possible values: table, json, yaml, none)")
 		flagSet.StringVar(&output, "o", "", "Output format (possible values: table, json, yaml, none)")
@@ -164,6 +176,9 @@ func (parser ConfigCLIParser) Parse() (*Config, error) {
 		flagSet.DurationVar(&timeout, "timeout", 0, "Timeout for the request (e.g. 400ms, 15s, 1m10s)")
 		flagSet.DurationVar(&timeout, "T", 0, "Timeout for the request (e.g. 400ms, 15s, 1m10s)")
 
+		flagSet.Var(&maxResponseBody, "max-response-body", "Largest response body to read (e.g. 1048576, 10MiB, 2MB), 0 for no limit")
+		flagSet.Var(&maxResponseBody, "S", "Largest response body to read (e.g. 1048576, 10MiB, 2MB), 0 for no limit")
+
 		flagSet.BoolVar(&insecure, "insecure", false, "Skip SSL/TLS certificate verification")
 		flagSet.BoolVar(&insecure, "I", false, "Skip SSL/TLS certificate verification")
 
@@ -205,8 +220,12 @@ func (parser ConfigCLIParser) Parse() (*Config, error) {
 			config.Requests = new(requestCount)
 		case "duration", "d":
 			config.Duration = new(duration)
-		case "quiet", "q":
+		case "log-level", "l":
-			config.Quiet = new(quiet)
+			config.LogLevel = new(logLevel)
+		case "log-file", "w":
+			config.LogFile = new(logFile)
+		case "progress", "p":
+			config.Progress = new(ConfigProgressType(progress))
 		case "output", "o":
 			config.Output = new(ConfigOutputType(output))
 		case "dry-run", "z":
@@ -244,6 +263,8 @@ func (parser ConfigCLIParser) Parse() (*Config, error) {
 			config.Values = append(config.Values, values...)
 		case "timeout", "T":
 			config.Timeout = new(timeout)
+		case "max-response-body", "S":
+			config.MaxResponseBody = new(uint64(maxResponseBody))
 		case "insecure", "I":
 			config.Insecure = new(insecure)
 		case "lua":
@@ -265,12 +286,14 @@ func (parser ConfigCLIParser) PrintHelp() {
 		cliUsageText+"\n",
 		Defaults.ShowConfig,
 		Defaults.Concurrency,
-		Defaults.Quiet,
+		Defaults.LogLevel,
+		Defaults.Progress,
 		Defaults.Output,
 		Defaults.DryRun,
 
 		Defaults.Method,
 		Defaults.RequestTimeout,
+		types.FormatByteSize(Defaults.MaxResponseBody),
 		Defaults.Insecure,
 	)
 }

internal/config/config.go

@@ -6,17 +6,18 @@ import (
 	"fmt"
 	"net/url"
 	"os"
+	"path/filepath"
 	"slices"
 	"strconv"
 	"strings"
 	"time"
 
-	"github.com/charmbracelet/bubbles/viewport"
+	"charm.land/bubbles/v2/viewport"
-	tea "github.com/charmbracelet/bubbletea"
+	tea "charm.land/bubbletea/v2"
-	"github.com/charmbracelet/glamour"
+	"charm.land/glamour/v2"
-	"github.com/charmbracelet/glamour/styles"
+	"charm.land/glamour/v2/styles"
-	"github.com/charmbracelet/lipgloss"
+	"charm.land/lipgloss/v2"
-	"github.com/charmbracelet/x/term"
+	"go.aykhans.me/sarin/internal/sarin"
 	"go.aykhans.me/sarin/internal/script"
 	"go.aykhans.me/sarin/internal/types"
 	"go.aykhans.me/sarin/internal/version"
@@ -26,30 +27,35 @@ import (
 )
 
 var Defaults = struct {
-	UserAgent      string
+	UserAgent       string
-	Method         string
+	Method          string
-	RequestTimeout time.Duration
+	RequestTimeout  time.Duration
-	Concurrency    uint
+	MaxResponseBody uint64
-	ShowConfig     bool
+	Concurrency     uint
-	Quiet          bool
+	ShowConfig      bool
-	Insecure       bool
+	Progress        ConfigProgressType
-	Output         ConfigOutputType
+	Insecure        bool
-	DryRun         bool
+	Output          ConfigOutputType
+	DryRun          bool
+	LogLevel        string
 }{
-	UserAgent:      "Sarin/" + version.Version,
+	UserAgent:       "Sarin/" + version.Version,
-	Method:         "GET",
+	Method:          "GET",
-	RequestTimeout: time.Second * 10,
+	RequestTimeout:  time.Second * 10,
-	Concurrency:    1,
+	MaxResponseBody: 10 << 20, // 10 MiB
-	ShowConfig:     false,
+	Concurrency:     1,
-	Quiet:          false,
+	ShowConfig:      false,
-	Insecure:       false,
+	Progress:        ConfigProgressTypeBar,
-	Output:         ConfigOutputTypeTable,
+	Insecure:        false,
-	DryRun:         false,
+	Output:          ConfigOutputTypeTable,
+	DryRun:          false,
+	LogLevel:        "error",
 }
 
 var (
 	ValidProxySchemes      = []string{"http", "https", "socks5", "socks5h"}
 	ValidRequestURLSchemes = []string{"http", "https"}
+	ValidLogLevels         = []string{"info", "error"}
 )
 
 var (
@@ -70,27 +76,37 @@ var (
 	ConfigOutputTypeNone  ConfigOutputType = "none"
 )
 
+type ConfigProgressType string
+
+var (
+	ConfigProgressTypeBar  ConfigProgressType = "bar"
+	ConfigProgressTypeNone ConfigProgressType = "none"
+)
+
 type Config struct {
-	ShowConfig  *bool              `yaml:"showConfig,omitempty"`
+	ShowConfig      *bool               `yaml:"showConfig,omitempty"`
-	Files       []types.ConfigFile `yaml:"files,omitempty"`
+	Files           []types.ConfigFile  `yaml:"files,omitempty"`
-	Methods     []string           `yaml:"methods,omitempty"`
+	Methods         []string            `yaml:"methods,omitempty"`
-	URL         *url.URL           `yaml:"url,omitempty"`
+	URL             *url.URL            `yaml:"url,omitempty"`
-	Timeout     *time.Duration     `yaml:"timeout,omitempty"`
+	Timeout         *time.Duration      `yaml:"timeout,omitempty"`
-	Concurrency *uint              `yaml:"concurrency,omitempty"`
+	MaxResponseBody *uint64             `yaml:"maxResponseBody,omitempty"`
-	Requests    *uint64            `yaml:"requests,omitempty"`
+	Concurrency     *uint               `yaml:"concurrency,omitempty"`
-	Duration    *time.Duration     `yaml:"duration,omitempty"`
+	Requests        *uint64             `yaml:"requests,omitempty"`
-	Quiet       *bool              `yaml:"quiet,omitempty"`
+	Duration        *time.Duration      `yaml:"duration,omitempty"`
-	Output      *ConfigOutputType  `yaml:"output,omitempty"`
+	Progress        *ConfigProgressType `yaml:"progress,omitempty"`
-	Insecure    *bool              `yaml:"insecure,omitempty"`
+	Output          *ConfigOutputType   `yaml:"output,omitempty"`
-	DryRun      *bool              `yaml:"dryRun,omitempty"`
+	Insecure        *bool               `yaml:"insecure,omitempty"`
-	Params      types.Params       `yaml:"params,omitempty"`
+	DryRun          *bool               `yaml:"dryRun,omitempty"`
-	Headers     types.Headers      `yaml:"headers,omitempty"`
+	Params          types.Params        `yaml:"params,omitempty"`
-	Cookies     types.Cookies      `yaml:"cookies,omitempty"`
+	Headers         types.Headers       `yaml:"headers,omitempty"`
-	Bodies      []string           `yaml:"bodies,omitempty"`
+	Cookies         types.Cookies       `yaml:"cookies,omitempty"`
-	Proxies     types.Proxies      `yaml:"proxies,omitempty"`
+	Bodies          []string            `yaml:"bodies,omitempty"`
-	Values      []string           `yaml:"values,omitempty"`
+	Proxies         types.Proxies       `yaml:"proxies,omitempty"`
-	Lua         []string           `yaml:"lua,omitempty"`
+	Values          []string            `yaml:"values,omitempty"`
-	Js          []string           `yaml:"js,omitempty"`
+	Lua             []string            `yaml:"lua,omitempty"`
+	Js              []string            `yaml:"js,omitempty"`
+	LogLevel        *string             `yaml:"logLevel,omitempty"`
+	LogFile         *string             `yaml:"logFile,omitempty"`
 }
 
 func (config Config) MarshalYAML() (any, error) {
@@ -164,6 +180,9 @@ func (config Config) MarshalYAML() (any, error) {
 	if config.Timeout != nil {
 		addField(content, "timeout", toNode(*config.Timeout), "")
 	}
+	if config.MaxResponseBody != nil {
+		addField(content, "maxResponseBody", toNode(types.FormatByteSize(*config.MaxResponseBody)), "")
+	}
 	if config.Concurrency != nil {
 		addField(content, "concurrency", toNode(*config.Concurrency), "")
 	}
@@ -173,8 +192,8 @@ func (config Config) MarshalYAML() (any, error) {
 	if config.Duration != nil {
 		addField(content, "duration", toNode(*config.Duration), "")
 	}
-	if config.Quiet != nil {
+	if config.Progress != nil {
-		addField(content, "quiet", toNode(*config.Quiet), "")
+		addField(content, "progress", toNode(string(*config.Progress)), "")
 	}
 	if config.Output != nil {
 		addField(content, "output", toNode(string(*config.Output)), "")
@@ -221,6 +240,13 @@ func (config Config) MarshalYAML() (any, error) {
 	addStringSlice(content, "values", config.Values, false)
 	addStringSlice(content, "lua", config.Lua, false)
 	addStringSlice(content, "js", config.Js, false)
+	if config.LogLevel != nil {
+		addField(content, "logLevel", toNode(*config.LogLevel), "")
+	}
+
+	if config.LogFile != nil {
+		addField(content, "logFile", toNode(*config.LogFile), "")
+	}
 
 	return root, nil
 }
@@ -228,12 +254,12 @@ func (config Config) MarshalYAML() (any, error) {
 func (config Config) Print() bool {
 	configYAML, err := yaml.Marshal(config)
 	if err != nil {
-		fmt.Fprintln(os.Stderr, StyleRed.Render("Error marshaling config to yaml: "+err.Error()))
+		fmt.Fprint(os.Stderr, lipgloss.Sprintln(StyleRed.Render("Error marshaling config to yaml: "+err.Error())))
 		os.Exit(1)
 	}
 
 	// Pipe mode: output raw content directly
-	if !term.IsTerminal(os.Stdout.Fd()) {
+	if !sarin.IsInteractiveTerminal(os.Stdout.Fd()) {
 		fmt.Println(string(configYAML))
 		os.Exit(0)
 	}
@@ -247,25 +273,23 @@ func (config Config) Print() bool {
 		glamour.WithWordWrap(0),
 	)
 	if err != nil {
-		fmt.Fprintln(os.Stderr, StyleRed.Render(err.Error()))
+		fmt.Fprint(os.Stderr, lipgloss.Sprintln(StyleRed.Render(err.Error())))
 		os.Exit(1)
 	}
 
 	content, err := renderer.Render("```yaml\n" + string(configYAML) + "```")
 	if err != nil {
-		fmt.Fprintln(os.Stderr, StyleRed.Render(err.Error()))
+		fmt.Fprint(os.Stderr, lipgloss.Sprintln(StyleRed.Render(err.Error())))
 		os.Exit(1)
 	}
 
 	p := tea.NewProgram(
 		printConfigModel{content: strings.Trim(content, "\n"), rawContent: configYAML},
-		tea.WithAltScreen(),
-		tea.WithMouseCellMotion(),
 	)
 
 	m, err := p.Run()
 	if err != nil {
-		fmt.Fprintln(os.Stderr, StyleRed.Render(err.Error()))
+		fmt.Fprint(os.Stderr, lipgloss.Sprintln(StyleRed.Render(err.Error())))
 		os.Exit(1)
 	}
 
@@ -283,6 +307,9 @@ func (config *Config) Merge(newConfig *Config) {
 	if newConfig.Timeout != nil {
 		config.Timeout = newConfig.Timeout
 	}
+	if newConfig.MaxResponseBody != nil {
+		config.MaxResponseBody = newConfig.MaxResponseBody
+	}
 	if newConfig.Concurrency != nil {
 		config.Concurrency = newConfig.Concurrency
 	}
@@ -295,8 +322,8 @@ func (config *Config) Merge(newConfig *Config) {
 	if newConfig.ShowConfig != nil {
 		config.ShowConfig = newConfig.ShowConfig
 	}
-	if newConfig.Quiet != nil {
+	if newConfig.Progress != nil {
-		config.Quiet = newConfig.Quiet
+		config.Progress = newConfig.Progress
 	}
 	if newConfig.Output != nil {
 		config.Output = newConfig.Output
@@ -331,6 +358,12 @@ func (config *Config) Merge(newConfig *Config) {
 	if len(newConfig.Js) != 0 {
 		config.Js = append(config.Js, newConfig.Js...)
 	}
+	if newConfig.LogLevel != nil {
+		config.LogLevel = newConfig.LogLevel
+	}
+	if newConfig.LogFile != nil {
+		config.LogFile = newConfig.LogFile
+	}
 }
 
 func (config *Config) SetDefaults() {
@@ -355,14 +388,17 @@ func (config *Config) SetDefaults() {
 	if config.Timeout == nil {
 		config.Timeout = &Defaults.RequestTimeout
 	}
+	if config.MaxResponseBody == nil {
+		config.MaxResponseBody = &Defaults.MaxResponseBody
+	}
 	if config.Concurrency == nil {
 		config.Concurrency = new(Defaults.Concurrency)
 	}
 	if config.ShowConfig == nil {
 		config.ShowConfig = new(Defaults.ShowConfig)
 	}
-	if config.Quiet == nil {
+	if config.Progress == nil {
-		config.Quiet = new(Defaults.Quiet)
+		config.Progress = new(Defaults.Progress)
 	}
 	if config.Insecure == nil {
 		config.Insecure = new(Defaults.Insecure)
@@ -377,6 +413,14 @@ func (config *Config) SetDefaults() {
 	if config.Output == nil {
 		config.Output = new(Defaults.Output)
 	}
+
+	if config.LogLevel == nil {
+		config.LogLevel = new(Defaults.LogLevel)
+	}
+
+	if config.LogFile == nil {
+		config.LogFile = new("")
+	}
 }
 
 // Validate validates the config fields.
@@ -422,12 +466,33 @@ func (config Config) Validate() error {
 		validationErrors = append(validationErrors, types.NewFieldValidationError("Timeout", "0", errors.New("timeout must be greater than 0")))
 	}
 
+	if config.MaxResponseBody != nil && *config.MaxResponseBody > types.ByteSizeLimit {
+		validationErrors = append(validationErrors, types.NewFieldValidationError(
+			"MaxResponseBody",
+			types.FormatByteSize(*config.MaxResponseBody),
+			errors.New("max response body must not exceed "+types.FormatByteSize(types.ByteSizeLimit)),
+		))
+	}
+
 	if config.ShowConfig == nil {
 		validationErrors = append(validationErrors, types.NewFieldValidationError("ShowConfig", "", errors.New("showConfig field is required")))
 	}
 
-	if config.Quiet == nil {
+	if config.Progress == nil {
-		validationErrors = append(validationErrors, types.NewFieldValidationError("Quiet", "", errors.New("quiet field is required")))
+		validationErrors = append(validationErrors, types.NewFieldValidationError("Progress", "", errors.New("progress field is required")))
+	} else {
+		switch *config.Progress {
+		case ConfigProgressTypeBar, ConfigProgressTypeNone:
+		default:
+			validationErrors = append(
+				validationErrors,
+				types.NewFieldValidationError(
+					"Progress",
+					string(*config.Progress),
+					fmt.Errorf("progress must be one of: %s, %s", ConfigProgressTypeBar, ConfigProgressTypeNone),
+				),
+			)
+		}
 	}
 
 	if config.Output == nil {
@@ -460,6 +525,36 @@ func (config Config) Validate() error {
 		validationErrors = append(validationErrors, types.NewFieldValidationError("DryRun", "", errors.New("dryRun field is required")))
 	}
 
+	if config.LogLevel != nil {
+		for i, level := range sarin.SplitLogLevels(*config.LogLevel) {
+			if !slices.Contains(ValidLogLevels, level) {
+				validationErrors = append(
+					validationErrors,
+					types.NewFieldValidationError(
+						fmt.Sprintf("LogLevel[%d]", i),
+						level,
+						fmt.Errorf("log level must be one of: %s", strings.Join(ValidLogLevels, ", ")),
+					),
+				)
+			}
+		}
+	}
+
+	if config.LogFile != nil && *config.LogFile != "" {
+		dir := filepath.Dir(*config.LogFile)
+		if info, err := os.Stat(dir); err != nil {
+			validationErrors = append(
+				validationErrors,
+				types.NewFieldValidationError("LogFile", *config.LogFile, fmt.Errorf("parent directory %q is not accessible", dir)),
+			)
+		} else if !info.IsDir() {
+			validationErrors = append(
+				validationErrors,
+				types.NewFieldValidationError("LogFile", *config.LogFile, fmt.Errorf("parent path %q is not a directory", dir)),
+			)
+		}
+	}
+
 	for i, proxy := range config.Proxies {
 		if !slices.Contains(ValidProxySchemes, proxy.Scheme) {
 			validationErrors = append(
@@ -538,11 +633,11 @@ func ReadAllConfigs() *Config {
 	_ = utilsErr.MustHandle(err,
 		utilsErr.OnType(func(err types.CLIUnexpectedArgsError) error {
 			cliParser.PrintHelp()
-			fmt.Fprintln(os.Stderr,
+			fmt.Fprint(os.Stderr, lipgloss.Sprintln(
 				StyleYellow.Render(
 					"\nUnexpected CLI arguments provided: ",
 				)+strings.Join(err.Args, ", "),
-			)
+			))
 			os.Exit(1)
 			return nil
 		}),
@@ -557,28 +652,35 @@ func ReadAllConfigs() *Config {
 
 	for _, configFile := range append(envConfig.Files, cliConf.Files...) {
 		fileConfig, err := parseConfigFile(configFile, 10)
+
+		// A nested configFile fails under its own name, not the one given on the command line.
+		path := configFile.Path()
+		if configFileErr, ok := errors.AsType[types.ConfigFileError](err); ok {
+			path = configFileErr.Path
+		}
+
 		_ = utilsErr.MustHandle(err,
 			utilsErr.OnType(func(err types.ConfigFileReadError) error {
 				cliParser.PrintHelp()
-				fmt.Fprintln(os.Stderr,
+				fmt.Fprint(os.Stderr, lipgloss.Sprintln(
 					StyleYellow.Render(
-						fmt.Sprintf("\nFailed to read config file (%s): ", configFile.Path())+err.Error(),
+						fmt.Sprintf("\nFailed to read config file (%s): ", path)+err.Error(),
 					),
-				)
+				))
 				os.Exit(1)
 				return nil
 			}),
 			utilsErr.OnType(func(err types.UnmarshalError) error {
-				fmt.Fprintln(os.Stderr,
+				fmt.Fprint(os.Stderr, lipgloss.Sprintln(
 					StyleYellow.Render(
-						fmt.Sprintf("\nFailed to parse config file (%s): ", configFile.Path())+err.Error(),
+						fmt.Sprintf("\nFailed to parse config file (%s): ", path)+err.Error(),
 					),
-				)
+				))
 				os.Exit(1)
 				return nil
 			}),
 			utilsErr.OnType(func(err types.FieldParseErrors) error {
-				printParseErrors(fmt.Sprintf("CONFIG FILE '%s'", configFile.Path()), err.Errors...)
+				printParseErrors(fmt.Sprintf("CONFIG FILE '%s'", path), err.Errors...)
 				os.Exit(1)
 				return nil
 			}),
@@ -594,7 +696,7 @@ func ReadAllConfigs() *Config {
 
 // parseConfigFile recursively parses a config file and its nested files up to maxDepth levels.
 // Returns the merged configuration or an error if parsing fails.
-// It can return the following errors:
+// It can return the following errors, each wrapped in a types.ConfigFileError naming the file:
 // - types.ConfigFileReadError
 // - types.UnmarshalError
 // - types.FieldParseErrors
@@ -602,7 +704,7 @@ func parseConfigFile(configFile types.ConfigFile, maxDepth int) (*Config, error)
 	configFileParser := NewConfigFileParser(configFile)
 	fileConfig, err := configFileParser.Parse()
 	if err != nil {
-		return nil, err
+		return nil, types.NewConfigFileError(configFile.Path(), err)
 	}
 
 	if maxDepth <= 0 {
@@ -640,7 +742,7 @@ func validateScriptSource(script string) error {
 		return types.ErrScriptEmpty
 	}
 
-	// Not a file/URL reference - it's an inline script
+	// Not a file/URL reference, so it's an inline script
 	if !strings.HasPrefix(script, "@") {
 		return nil
 	}
@@ -650,7 +752,7 @@ func validateScriptSource(script string) error {
 		return nil
 	}
 
-	// It's a file or URL reference - validate the source
+	// It's a file or URL reference, so validate the source
 	source := script[1:] // Remove the @ prefix
 
 	if source == "" {
@@ -669,20 +771,20 @@ func validateScriptSource(script string) error {
 		return nil
 	}
 
-	// It's a file path - basic validation (not empty, checked above)
+	// It's a file path, already checked to be non-empty above
 	return nil
 }
 
 func printParseErrors(parserName string, errors ...types.FieldParseError) {
 	for _, fieldErr := range errors {
 		if fieldErr.Value == "" {
-			fmt.Fprintln(os.Stderr,
+			fmt.Fprint(os.Stderr, lipgloss.Sprintln(
 				StyleYellow.Render(fmt.Sprintf("[%s] Field '%s': ", parserName, fieldErr.Field))+fieldErr.Err.Error(),
-			)
+			))
 		} else {
-			fmt.Fprintln(os.Stderr,
+			fmt.Fprint(os.Stderr, lipgloss.Sprintln(
 				StyleYellow.Render(fmt.Sprintf("[%s] Field '%s' (%s): ", parserName, fieldErr.Field, fieldErr.Value))+fieldErr.Err.Error(),
-			)
+			))
 		}
 	}
 }
@@ -723,7 +825,7 @@ func (m printConfigModel) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 	var cmd tea.Cmd
 
 	switch msg := msg.(type) {
-	case tea.KeyMsg:
+	case tea.KeyPressMsg:
 		switch msg.String() {
 		case "ctrl+c", "esc":
 			return m, tea.Quit
@@ -746,13 +848,22 @@ func (m printConfigModel) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 	return m, cmd
 }
 
-func (m printConfigModel) View() string {
+func (m printConfigModel) View() tea.View {
+	// AltScreen and MouseMode were program options in bubbletea v1, in v2 they
+	// are view properties, so every return path has to declare them.
+	newView := func(s string) tea.View {
+		v := tea.NewView(s)
+		v.AltScreen = true
+		v.MouseMode = tea.MouseModeCellMotion
+		return v
+	}
+
 	if !m.ready {
-		return "\n  Initializing..."
+		return newView("\n  Initializing...")
 	}
 
 	content := lipgloss.JoinHorizontal(lipgloss.Top, m.viewport.View(), m.scrollbar())
-	return fmt.Sprintf("%s\n%s\n%s", m.headerView(), content, m.footerView())
+	return newView(fmt.Sprintf("%s\n%s\n%s", m.headerView(), content, m.footerView()))
 }
 
 func (m *printConfigModel) saveContent() (printConfigModel, tea.Cmd) {
@@ -772,12 +883,13 @@ func (m *printConfigModel) handleResize(msg tea.WindowSizeMsg) {
 	width := msg.Width - scrollbarWidth
 
 	if !m.ready {
-		m.viewport = viewport.New(width, height)
+		m.viewport = viewport.New(viewport.WithWidth(width), viewport.WithHeight(height))
+		m.viewport.SetHorizontalStep(0)
 		m.viewport.SetContent(m.contentWithLineNumbers())
 		m.ready = true
 	} else {
-		m.viewport.Width = width
+		m.viewport.SetWidth(width)
-		m.viewport.Height = height
+		m.viewport.SetHeight(height)
 	}
 }
 
@@ -792,12 +904,12 @@ func (m printConfigModel) headerView() string {
 			printConfigKeyStyle.Render("ESC") + printConfigDescStyle.Render(" exit")
 		title = printConfigHelpStyle.Render(help)
 	}
-	line := strings.Repeat("─", max(0, m.viewport.Width+scrollbarWidth-lipgloss.Width(title)))
+	line := strings.Repeat("─", max(0, m.viewport.Width()+scrollbarWidth-lipgloss.Width(title)))
 	return lipgloss.JoinHorizontal(lipgloss.Center, title, line)
 }
 
 func (m printConfigModel) footerView() string {
-	return strings.Repeat("─", m.viewport.Width+scrollbarWidth)
+	return strings.Repeat("─", m.viewport.Width()+scrollbarWidth)
 }
 
 func (m printConfigModel) contentWithLineNumbers() string {
@@ -819,7 +931,7 @@ func (m printConfigModel) contentWithLineNumbers() string {
 }
 
 func (m printConfigModel) scrollbar() string {
-	height := m.viewport.Height
+	height := m.viewport.Height()
 	trackHeight := height - scrollbarBottomSpace
 	totalLines := m.viewport.TotalLineCount()
 

internal/config/env.go

@@ -49,74 +49,6 @@ func (parser ConfigENVParser) Parse() (*Config, error) {
 		config.Files = append(config.Files, *types.ParseConfigFile(configFile))
 	}
 
-	if quiet := parser.getEnv("QUIET"); quiet != "" {
-		quietParsed, err := utilsParse.ParseString[bool](quiet)
-		if err != nil {
-			fieldParseErrors = append(
-				fieldParseErrors,
-				types.NewFieldParseError(
-					parser.getFullEnvName("QUIET"),
-					quiet,
-					errors.New("invalid value for boolean, expected 'true' or 'false'"),
-				),
-			)
-		} else {
-			config.Quiet = &quietParsed
-		}
-	}
-
-	if output := parser.getEnv("OUTPUT"); output != "" {
-		config.Output = new(ConfigOutputType(output))
-	}
-
-	if insecure := parser.getEnv("INSECURE"); insecure != "" {
-		insecureParsed, err := utilsParse.ParseString[bool](insecure)
-		if err != nil {
-			fieldParseErrors = append(
-				fieldParseErrors,
-				types.NewFieldParseError(
-					parser.getFullEnvName("INSECURE"),
-					insecure,
-					errors.New("invalid value for boolean, expected 'true' or 'false'"),
-				),
-			)
-		} else {
-			config.Insecure = &insecureParsed
-		}
-	}
-
-	if dryRun := parser.getEnv("DRY_RUN"); dryRun != "" {
-		dryRunParsed, err := utilsParse.ParseString[bool](dryRun)
-		if err != nil {
-			fieldParseErrors = append(
-				fieldParseErrors,
-				types.NewFieldParseError(
-					parser.getFullEnvName("DRY_RUN"),
-					dryRun,
-					errors.New("invalid value for boolean, expected 'true' or 'false'"),
-				),
-			)
-		} else {
-			config.DryRun = &dryRunParsed
-		}
-	}
-
-	if method := parser.getEnv("METHOD"); method != "" {
-		config.Methods = []string{method}
-	}
-
-	if urlEnv := parser.getEnv("URL"); urlEnv != "" {
-		urlEnvParsed, err := url.Parse(urlEnv)
-		if err != nil {
-			fieldParseErrors = append(
-				fieldParseErrors,
-				types.NewFieldParseError(parser.getFullEnvName("URL"), urlEnv, err),
-			)
-		} else {
-			config.URL = urlEnvParsed
-		}
-	}
-
 	if concurrency := parser.getEnv("CONCURRENCY"); concurrency != "" {
 		concurrencyParsed, err := utilsParse.ParseString[uint](concurrency)
 		if err != nil {
@@ -165,22 +97,58 @@ func (parser ConfigENVParser) Parse() (*Config, error) {
 		}
 	}
 
-	if timeout := parser.getEnv("TIMEOUT"); timeout != "" {
+	if logLevel := parser.getEnv("LOG_LEVEL"); logLevel != "" {
-		timeoutParsed, err := utilsParse.ParseString[time.Duration](timeout)
+		config.LogLevel = new(logLevel)
+	}
+
+	if logFile := parser.getEnv("LOG_FILE"); logFile != "" {
+		config.LogFile = new(logFile)
+	}
+
+	if progress := parser.getEnv("PROGRESS"); progress != "" {
+		config.Progress = new(ConfigProgressType(progress))
+	}
+
+	if output := parser.getEnv("OUTPUT"); output != "" {
+		config.Output = new(ConfigOutputType(output))
+	}
+
+	if dryRun := parser.getEnv("DRY_RUN"); dryRun != "" {
+		dryRunParsed, err := utilsParse.ParseString[bool](dryRun)
 		if err != nil {
 			fieldParseErrors = append(
 				fieldParseErrors,
 				types.NewFieldParseError(
-					parser.getFullEnvName("TIMEOUT"),
+					parser.getFullEnvName("DRY_RUN"),
-					timeout,
+					dryRun,
-					errors.New("invalid value for duration, expected a duration string (e.g., '10s', '1h30m')"),
+					errors.New("invalid value for boolean, expected 'true' or 'false'"),
 				),
 			)
 		} else {
-			config.Timeout = &timeoutParsed
+			config.DryRun = &dryRunParsed
 		}
 	}
 
+	if urlEnv := parser.getEnv("URL"); urlEnv != "" {
+		urlEnvParsed, err := url.Parse(urlEnv)
+		if err != nil {
+			fieldParseErrors = append(
+				fieldParseErrors,
+				types.NewFieldParseError(parser.getFullEnvName("URL"), urlEnv, err),
+			)
+		} else {
+			config.URL = urlEnvParsed
+		}
+	}
+
+	if method := parser.getEnv("METHOD"); method != "" {
+		config.Methods = []string{method}
+	}
+
+	if body := parser.getEnv("BODY"); body != "" {
+		config.Bodies = []string{body}
+	}
+
 	if param := parser.getEnv("PARAM"); param != "" {
 		config.Params.Parse(param)
 	}
@@ -193,10 +161,6 @@ func (parser ConfigENVParser) Parse() (*Config, error) {
 		config.Cookies.Parse(cookie)
 	}
 
-	if body := parser.getEnv("BODY"); body != "" {
-		config.Bodies = []string{body}
-	}
-
 	if proxy := parser.getEnv("PROXY"); proxy != "" {
 		err := config.Proxies.Parse(proxy)
 		if err != nil {
@@ -215,6 +179,54 @@ func (parser ConfigENVParser) Parse() (*Config, error) {
 		config.Values = []string{values}
 	}
 
+	if timeout := parser.getEnv("TIMEOUT"); timeout != "" {
+		timeoutParsed, err := utilsParse.ParseString[time.Duration](timeout)
+		if err != nil {
+			fieldParseErrors = append(
+				fieldParseErrors,
+				types.NewFieldParseError(
+					parser.getFullEnvName("TIMEOUT"),
+					timeout,
+					errors.New("invalid value for duration, expected a duration string (e.g., '10s', '1h30m')"),
+				),
+			)
+		} else {
+			config.Timeout = &timeoutParsed
+		}
+	}
+
+	if maxResponseBody := parser.getEnv("MAX_RESPONSE_BODY"); maxResponseBody != "" {
+		maxResponseBodyParsed, err := types.ParseByteSize(maxResponseBody)
+		if err != nil {
+			fieldParseErrors = append(
+				fieldParseErrors,
+				types.NewFieldParseError(
+					parser.getFullEnvName("MAX_RESPONSE_BODY"),
+					maxResponseBody,
+					err,
+				),
+			)
+		} else {
+			config.MaxResponseBody = &maxResponseBodyParsed
+		}
+	}
+
+	if insecure := parser.getEnv("INSECURE"); insecure != "" {
+		insecureParsed, err := utilsParse.ParseString[bool](insecure)
+		if err != nil {
+			fieldParseErrors = append(
+				fieldParseErrors,
+				types.NewFieldParseError(
+					parser.getFullEnvName("INSECURE"),
+					insecure,
+					errors.New("invalid value for boolean, expected 'true' or 'false'"),
+				),
+			)
+		} else {
+			config.Insecure = &insecureParsed
+		}
+	}
+
 	if lua := parser.getEnv("LUA"); lua != "" {
 		config.Lua = []string{lua}
 	}

internal/config/file.go

@@ -1,13 +1,17 @@
 package config
 
 import (
+	"bytes"
 	"context"
+	"errors"
 	"fmt"
 	"io"
 	"net/http"
 	"net/url"
 	"os"
 	"path/filepath"
+	"reflect"
+	"strconv"
 	"strings"
 	"time"
 
@@ -79,10 +83,18 @@ func fetchHTTP(ctx context.Context, url string) ([]byte, error) {
 		return nil, types.NewHTTPStatusError(url, resp.StatusCode, resp.Status)
 	}
 
-	data, err := io.ReadAll(resp.Body)
+	// A declared size above the limit is refused before anything is read.
+	if resp.ContentLength > types.RemoteFetchLimit {
+		return nil, types.NewHTTPFetchError(url, types.ErrRemoteFileTooLarge)
+	}
+
+	data, err := io.ReadAll(io.LimitReader(resp.Body, types.RemoteFetchLimit+1))
 	if err != nil {
 		return nil, types.NewHTTPFetchError(url, err)
 	}
+	if len(data) > types.RemoteFetchLimit {
+		return nil, types.NewHTTPFetchError(url, types.ErrRemoteFileTooLarge)
+	}
 
 	return data, nil
 }
@@ -126,7 +138,7 @@ func (ss *stringOrSliceField) UnmarshalYAML(node *yaml.Node) error {
 		*ss = slice
 		return nil
 	default:
-		return fmt.Errorf("expected a string or a sequence of strings, but got %v", node.Kind)
+		return fmt.Errorf("expected a string or a sequence of strings, but got %s", yamlNodeName(node))
 	}
 }
 
@@ -147,7 +159,7 @@ func (kv *keyValuesField) UnmarshalYAML(node *yaml.Node) error {
 		// Handle sequence of maps: [{key1: value1}, {key2: value2}]
 		for _, item := range node.Content {
 			if item.Kind != yaml.MappingNode {
-				return fmt.Errorf("expected a mapping in sequence, but got %v", item.Kind)
+				return fmt.Errorf("expected a mapping in sequence, but got %s", yamlNodeName(item))
 			}
 			if err := kv.unmarshalMapping(item); err != nil {
 				return err
@@ -155,7 +167,7 @@ func (kv *keyValuesField) UnmarshalYAML(node *yaml.Node) error {
 		}
 		return nil
 	default:
-		return fmt.Errorf("expected a mapping or sequence of mappings, but got %v", node.Kind)
+		return fmt.Errorf("expected a mapping or sequence of mappings, but got %s", yamlNodeName(node))
 	}
 }
 
@@ -166,7 +178,7 @@ func (kv *keyValuesField) unmarshalMapping(node *yaml.Node) error {
 		valueNode := node.Content[i+1]
 
 		if keyNode.Kind != yaml.ScalarNode {
-			return fmt.Errorf("expected a string key, but got %v", keyNode.Kind)
+			return fmt.Errorf("expected a string key, but got %s", yamlNodeName(keyNode))
 		}
 
 		key := keyNode.Value
@@ -178,12 +190,12 @@ func (kv *keyValuesField) unmarshalMapping(node *yaml.Node) error {
 		case yaml.SequenceNode:
 			for _, v := range valueNode.Content {
 				if v.Kind != yaml.ScalarNode {
-					return fmt.Errorf("expected string values in array for key %q, but got %v", key, v.Kind)
+					return fmt.Errorf("expected string values in array for key %q, but got %s", key, yamlNodeName(v))
 				}
 				values = append(values, v.Value)
 			}
 		default:
-			return fmt.Errorf("expected a string or array of strings for key %q, but got %v", key, valueNode.Kind)
+			return fmt.Errorf("expected a string or array of strings for key %q, but got %s", key, yamlNodeName(valueNode))
 		}
 
 		*kv = append(*kv, types.KeyValue[string, []string]{Key: key, Value: values})
@@ -192,26 +204,29 @@ func (kv *keyValuesField) unmarshalMapping(node *yaml.Node) error {
 }
 
 type configYAML struct {
-	ConfigFiles  stringOrSliceField `yaml:"configFile"`
+	ShowConfig      *bool              `yaml:"showConfig"`
-	Method       stringOrSliceField `yaml:"method"`
+	ConfigFiles     stringOrSliceField `yaml:"configFile"`
-	URL          *string            `yaml:"url"`
+	Concurrency     *uint              `yaml:"concurrency"`
-	Timeout      *time.Duration     `yaml:"timeout"`
+	RequestCount    *uint64            `yaml:"requests"`
-	Concurrency  *uint              `yaml:"concurrency"`
+	Duration        *time.Duration     `yaml:"duration"`
-	RequestCount *uint64            `yaml:"requests"`
+	LogLevel        *string            `yaml:"logLevel"`
-	Duration     *time.Duration     `yaml:"duration"`
+	LogFile         *string            `yaml:"logFile"`
-	Quiet        *bool              `yaml:"quiet"`
+	Progress        *string            `yaml:"progress"`
-	Output       *string            `yaml:"output"`
+	Output          *string            `yaml:"output"`
-	Insecure     *bool              `yaml:"insecure"`
+	DryRun          *bool              `yaml:"dryRun"`
-	ShowConfig   *bool              `yaml:"showConfig"`
+	URL             *string            `yaml:"url"`
-	DryRun       *bool              `yaml:"dryRun"`
+	Method          stringOrSliceField `yaml:"method"`
-	Params       keyValuesField     `yaml:"params"`
+	Bodies          stringOrSliceField `yaml:"body"`
-	Headers      keyValuesField     `yaml:"headers"`
+	Params          keyValuesField     `yaml:"params"`
-	Cookies      keyValuesField     `yaml:"cookies"`
+	Headers         keyValuesField     `yaml:"headers"`
-	Bodies       stringOrSliceField `yaml:"body"`
+	Cookies         keyValuesField     `yaml:"cookies"`
-	Proxies      stringOrSliceField `yaml:"proxy"`
+	Proxies         stringOrSliceField `yaml:"proxy"`
-	Values       stringOrSliceField `yaml:"values"`
+	Values          stringOrSliceField `yaml:"values"`
-	Lua          stringOrSliceField `yaml:"lua"`
+	Timeout         *time.Duration     `yaml:"timeout"`
-	Js           stringOrSliceField `yaml:"js"`
+	MaxResponseBody *byteSize          `yaml:"maxResponseBody"`
+	Insecure        *bool              `yaml:"insecure"`
+	Lua             stringOrSliceField `yaml:"lua"`
+	Js              stringOrSliceField `yaml:"js"`
 }
 
 // ParseYAML parses YAML config file arguments into a Config object.
@@ -224,40 +239,31 @@ func (parser ConfigFileParser) ParseYAML(data []byte) (*Config, error) {
 		parsedData = &configYAML{}
 	)
 
-	err := yaml.Unmarshal(data, &parsedData)
+	decoder := yaml.NewDecoder(bytes.NewReader(data))
-	if err != nil {
+	decoder.KnownFields(true)
-		return nil, types.NewUnmarshalError(err)
+	// The decoder returns a bare io.EOF for an empty file, errors.Is would also match a wrapped one.
+	if err := decoder.Decode(parsedData); err != nil && err != io.EOF { //nolint:errorlint
+		return nil, types.NewUnmarshalError(yamlError(err))
+	}
+
+	// Decode reads one document, so anything after the first "---" would be dropped silently.
+	for {
+		var next yaml.Node
+		err := decoder.Decode(&next)
+		if err == io.EOF { //nolint:errorlint
+			break
+		}
+		if err != nil {
+			return nil, types.NewUnmarshalError(yamlError(err))
+		}
+		if !isEmptyDocument(&next) {
+			return nil, types.NewUnmarshalError(types.ErrYAMLMultipleDocuments)
+		}
 	}
 
 	var fieldParseErrors []types.FieldParseError
 
-	config.Methods = append(config.Methods, parsedData.Method...)
-	config.Timeout = parsedData.Timeout
-	config.Concurrency = parsedData.Concurrency
-	config.Requests = parsedData.RequestCount
-	config.Duration = parsedData.Duration
 	config.ShowConfig = parsedData.ShowConfig
-	config.Quiet = parsedData.Quiet
-
-	if parsedData.Output != nil {
-		config.Output = new(ConfigOutputType(*parsedData.Output))
-	}
-
-	config.Insecure = parsedData.Insecure
-	config.DryRun = parsedData.DryRun
-	for _, kv := range parsedData.Params {
-		config.Params = append(config.Params, types.Param(kv))
-	}
-	for _, kv := range parsedData.Headers {
-		config.Headers = append(config.Headers, types.Header(kv))
-	}
-	for _, kv := range parsedData.Cookies {
-		config.Cookies = append(config.Cookies, types.Cookie(kv))
-	}
-	config.Bodies = append(config.Bodies, parsedData.Bodies...)
-	config.Values = append(config.Values, parsedData.Values...)
-	config.Lua = append(config.Lua, parsedData.Lua...)
-	config.Js = append(config.Js, parsedData.Js...)
 
 	if len(parsedData.ConfigFiles) > 0 {
 		for _, configFile := range parsedData.ConfigFiles {
@@ -265,6 +271,22 @@ func (parser ConfigFileParser) ParseYAML(data []byte) (*Config, error) {
 		}
 	}
 
+	config.Concurrency = parsedData.Concurrency
+	config.Requests = parsedData.RequestCount
+	config.Duration = parsedData.Duration
+	config.LogLevel = parsedData.LogLevel
+	config.LogFile = parsedData.LogFile
+
+	if parsedData.Progress != nil {
+		config.Progress = new(ConfigProgressType(*parsedData.Progress))
+	}
+
+	if parsedData.Output != nil {
+		config.Output = new(ConfigOutputType(*parsedData.Output))
+	}
+
+	config.DryRun = parsedData.DryRun
+
 	if parsedData.URL != nil {
 		urlParsed, err := url.Parse(*parsedData.URL)
 		if err != nil {
@@ -274,6 +296,18 @@ func (parser ConfigFileParser) ParseYAML(data []byte) (*Config, error) {
 		}
 	}
 
+	config.Methods = append(config.Methods, parsedData.Method...)
+	config.Bodies = append(config.Bodies, parsedData.Bodies...)
+	for _, kv := range parsedData.Params {
+		config.Params = append(config.Params, types.Param(kv))
+	}
+	for _, kv := range parsedData.Headers {
+		config.Headers = append(config.Headers, types.Header(kv))
+	}
+	for _, kv := range parsedData.Cookies {
+		config.Cookies = append(config.Cookies, types.Cookie(kv))
+	}
+
 	for i, proxy := range parsedData.Proxies {
 		err := config.Proxies.Parse(proxy)
 		if err != nil {
@@ -284,9 +318,201 @@ func (parser ConfigFileParser) ParseYAML(data []byte) (*Config, error) {
 		}
 	}
 
+	config.Values = append(config.Values, parsedData.Values...)
+	config.Timeout = parsedData.Timeout
+	if parsedData.MaxResponseBody != nil {
+		config.MaxResponseBody = new(uint64(*parsedData.MaxResponseBody))
+	}
+	config.Insecure = parsedData.Insecure
+	config.Lua = append(config.Lua, parsedData.Lua...)
+	config.Js = append(config.Js, parsedData.Js...)
+
 	if len(fieldParseErrors) > 0 {
 		return nil, types.NewFieldParseErrors(fieldParseErrors)
 	}
 
 	return config, nil
 }
+
+// configYAMLTypeName is the Go type name the yaml package puts in its messages.
+var configYAMLTypeName = reflect.TypeFor[configYAML]().String()
+
+// isEmptyDocument reports whether a document holds nothing, which a trailing "---" produces.
+// A null tag alone is not enough, since a user can hang it on a mapping that does hold content.
+func isEmptyDocument(node *yaml.Node) bool {
+	if len(node.Content) == 0 {
+		return true
+	}
+	root := node.Content[0]
+	return root.Kind == yaml.ScalarNode && root.Tag == "!!null"
+}
+
+// yamlError rewrites yaml decode errors so they read like config file errors.
+// Errors from building the config arrive collected, everything earlier arrives on its own.
+func yamlError(err error) error {
+	var loadErrors *yaml.LoadErrors
+	if errors.As(err, &loadErrors) && len(loadErrors.Errors) > 0 {
+		var builder strings.Builder
+		for i, loadError := range loadErrors.Errors {
+			if i > 0 {
+				builder.WriteString("\n")
+			}
+			builder.WriteString(yamlErrorText(loadError))
+		}
+		return errors.New(builder.String())
+	}
+
+	if loadError, ok := errors.AsType[*yaml.LoadError](err); ok {
+		return errors.New(yamlErrorText(loadError))
+	}
+
+	return err
+}
+
+// yamlErrorText renders one error as "line 3: while scanning a plain scalar: found a tab character".
+// The mark is where reading gave up and the context mark starts the construct that broke.
+func yamlErrorText(loadError *yaml.LoadError) string {
+	var builder strings.Builder
+	if loadError.Mark.Line > 0 {
+		fmt.Fprintf(&builder, "line %d: ", loadError.Mark.Line)
+	}
+	if loadError.ContextMsg != "" {
+		builder.WriteString(loadError.ContextMsg + ": ")
+	}
+	builder.WriteString(yamlErrorMessage(loadError.Message))
+
+	start := loadError.ContextMark
+	if loadError.ContextMsg != "" && start.Line > 0 && start.Line != loadError.Mark.Line {
+		fmt.Fprintf(&builder, " (started at line %d)", start.Line)
+	}
+
+	return builder.String()
+}
+
+// yamlTypeNames maps the Go types and YAML tags the yaml package prints to words a user knows.
+var yamlTypeNames = map[string]string{
+	"!!str":            "text",
+	"!!int":            "a number",
+	"!!float":          "a number",
+	"!!bool":           "true or false",
+	"!!seq":            "a list",
+	"!!map":            "a mapping",
+	"!!null":           "an empty value",
+	"!!timestamp":      "a date",
+	"!!binary":         "binary data",
+	"string":           "text",
+	"bool":             "true or false",
+	"uint":             "a whole number of 0 or more",
+	"uint64":           "a whole number of 0 or more",
+	"time.Duration":    "a duration such as 10s",
+	configYAMLTypeName: "a mapping of config keys",
+}
+
+// yamlNodeName names what a node holds, so an error can say "a list" instead of a kind number.
+// A tag that contradicts the shape is kept, since the shape alone would read as a contradiction.
+func yamlNodeName(node *yaml.Node) string {
+	if name, ok := yamlTypeNames[node.Tag]; ok && yamlTagKind(node.Tag) == node.Kind {
+		return name
+	}
+	if node.Tag == "" {
+		return yamlKindName(node.Kind)
+	}
+	return yamlKindName(node.Kind) + " tagged " + node.Tag
+}
+
+// yamlTagKind returns the node shape a tag belongs on, so a mismatch can be spotted.
+func yamlTagKind(tag string) yaml.Kind {
+	switch tag {
+	case "!!seq":
+		return yaml.SequenceNode
+	case "!!map":
+		return yaml.MappingNode
+	default:
+		return yaml.ScalarNode
+	}
+}
+
+// yamlKindName names a node by its shape, for when its tag says nothing a user would know.
+func yamlKindName(kind yaml.Kind) string {
+	switch kind {
+	case yaml.SequenceNode:
+		return "a list"
+	case yaml.MappingNode:
+		return "a mapping"
+	case yaml.AliasNode:
+		return "an alias"
+	default:
+		return "a value"
+	}
+}
+
+// yamlErrorMessage turns "field x not found in type config.configYAML" into "unknown key "x"".
+func yamlErrorMessage(message string) string {
+	if field, ok := strings.CutSuffix(message, " not found in type "+configYAMLTypeName); ok {
+		if name, ok := strings.CutPrefix(field, "field "); ok {
+			return fmt.Sprintf("unknown key %q", name)
+		}
+	}
+
+	// The user controls the value, so the rightmost separator is the only one that is ours.
+	// After "as a" comes the tag the user wrote, after "into" comes the type the key accepts.
+	if names, ok := strings.CutPrefix(message, "cannot construct "); ok {
+		at, width, tagged := -1, 0, false
+		for index, separator := range []string{" into ", " as a "} {
+			if found := strings.LastIndex(names, separator); found > at {
+				at, width, tagged = found, len(separator), index == 1
+			}
+		}
+		if at >= 0 {
+			got, want := yamlGotName(names[:at]), yamlWantedName(names[at+width:])
+			if tagged {
+				return fmt.Sprintf("%s is not %s", got, want)
+			}
+			return fmt.Sprintf("expected %s, but got %s", want, got)
+		}
+	}
+
+	return strings.ReplaceAll(message, configYAMLTypeName, "the config file")
+}
+
+// yamlWantedName names what a key accepts, which the yaml package prints as a Go type.
+func yamlWantedName(text string) string {
+	if name, ok := yamlTypeNames[text]; ok {
+		return name
+	}
+	return text
+}
+
+// yamlGotName names what the file held, which the yaml package prints as a tag and sometimes a value.
+// A tag the user would not know stays in the text, since without it the message reads as nonsense.
+func yamlGotName(text string) string {
+	// A collection tag carries no backticks, so a scalar wearing one arrives glued to it.
+	for _, tag := range []string{"!!seq", "!!map"} {
+		if value, ok := strings.CutPrefix(text, tag); ok && value != "" {
+			return yamlValueText(value) + " tagged " + tag
+		}
+	}
+
+	tag, value, _ := strings.Cut(text, " ")
+	value = strings.TrimSuffix(strings.TrimPrefix(value, "`"), "`")
+
+	name, known := yamlTypeNames[tag]
+	switch {
+	case known && value != "":
+		return yamlValueText(value)
+	case known:
+		return name
+	case value != "":
+		return yamlValueText(value) + " tagged " + tag
+	default:
+		return "a value tagged " + tag
+	}
+}
+
+// yamlValueText quotes a value, saying so when the yaml package shortened it to seven characters.
+func yamlValueText(value string) string {
+	if start, ok := strings.CutSuffix(value, "..."); ok && len(start) == 7 {
+		return "a value starting with " + strconv.Quote(start)
+	}
+	return strconv.Quote(value)
+}

internal/config/template_validator.go

@@ -193,7 +193,7 @@ func validateTemplateURLPath(urlPath string, funcMap template.FuncMap) []types.F
 
 func ValidateTemplates(config *Config) []types.FieldValidationError {
 	// Create template function map using the same functions as sarin package
-	// Use nil for fileCache during validation - templates are only parsed, not executed
+	// fileCache is nil because templates are only parsed here, not executed
 	randSource := sarin.NewDefaultRandSource()
 	funcMap := sarin.NewDefaultTemplateFuncMap(randSource, nil)
 

internal/sarin/client.go

@@ -5,27 +5,19 @@ import (
 	"context"
 	"crypto/tls"
 	"encoding/base64"
-	"math"
 	"net"
 	"net/http"
 	"net/url"
 	"time"
 
 	"github.com/valyala/fasthttp"
-	"github.com/valyala/fasthttp/fasthttpproxy"
 	"go.aykhans.me/sarin/internal/types"
 	utilsSlice "go.aykhans.me/utils/slice"
 	"golang.org/x/net/proxy"
 )
 
-type HostClientGenerator func() *fasthttp.HostClient
+// clientIndexGenerator returns the index of the host client (and proxy) to use next.
-
+type clientIndexGenerator func() int
-func safeUintToInt(u uint) int {
-	if u > math.MaxInt {
-		return math.MaxInt
-	}
-	return int(u)
-}
 
 // NewHostClients creates a list of fasthttp.HostClient instances for the given proxies.
 // If no proxies are provided, a single client without a proxy is returned.
@@ -38,6 +30,7 @@ func NewHostClients(
 	maxConns uint,
 	requestURL *url.URL,
 	skipVerify bool,
+	maxResponseBody uint64,
 ) ([]*fasthttp.HostClient, error) {
 	isTLS := requestURL.Scheme == "https"
 
@@ -66,6 +59,9 @@ func NewHostClients(
 				MaxConnDuration:               timeout,
 				WriteTimeout:                  timeout,
 				ReadTimeout:                   timeout,
+				MaxResponseBodySize:           safeUint64ToInt(maxResponseBody),
+				MaxIdemponentCallAttempts:     1,
+				ReadBufferSize:                64 << 10, // 64 KiB
 				DisableHeaderNamesNormalizing: true,
 				DisablePathNormalizing:        true,
 				NoDefaultUserAgentHeader:      true,
@@ -77,8 +73,9 @@ func NewHostClients(
 	}
 
 	client := &fasthttp.HostClient{
-		MaxConns: safeUintToInt(maxConns),
+		MaxConns:      safeUintToInt(maxConns),
-		IsTLS:    isTLS,
+		IsTLS:         isTLS,
+		DialDualStack: true,
 		TLSConfig: &tls.Config{
 			InsecureSkipVerify: skipVerify, //nolint:gosec
 		},
@@ -87,6 +84,9 @@ func NewHostClients(
 		MaxConnDuration:               timeout,
 		WriteTimeout:                  timeout,
 		ReadTimeout:                   timeout,
+		MaxResponseBodySize:           safeUint64ToInt(maxResponseBody),
+		MaxIdemponentCallAttempts:     1,
+		ReadBufferSize:                64 << 10, // 64 KiB
 		DisableHeaderNamesNormalizing: true,
 		DisablePathNormalizing:        true,
 		NoDefaultUserAgentHeader:      true,
@@ -94,40 +94,45 @@ func NewHostClients(
 	return []*fasthttp.HostClient{client}, nil
 }
 
-// NewProxyDialFunc creates a dial function for the given proxy URL.
+// NewProxyDialFunc creates a dial function for the given proxy URL with a fixed timeout.
 // It can return the following errors:
 //   - types.ProxyUnsupportedSchemeError
+//   - types.ErrProxyNoContextDialer
 func NewProxyDialFunc(ctx context.Context, proxyURL *url.URL, timeout time.Duration) (fasthttp.DialFunc, error) {
-	var (
+	dial, err := NewProxyDialFuncWithTimeout(ctx, proxyURL)
-		dialer fasthttp.DialFunc
+	if err != nil {
-		err    error
+		return nil, err
-	)
+	}
 
+	return func(addr string) (net.Conn, error) {
+		return dial(addr, timeout)
+	}, nil
+}
+
+// NewProxyDialFuncWithTimeout creates a dial function for the given proxy URL that takes the timeout per call.
+// It can return the following errors:
+//   - types.ProxyUnsupportedSchemeError
+//   - types.ErrProxyNoContextDialer
+func NewProxyDialFuncWithTimeout(ctx context.Context, proxyURL *url.URL) (fasthttp.DialFuncWithTimeout, error) {
 	switch proxyURL.Scheme {
 	case "socks5":
-		dialer, err = fasthttpSocksDialerDualStackTimeout(ctx, proxyURL, timeout, true)
+		return fasthttpSocksDialer(ctx, proxyURL, true)
-		if err != nil {
-			return nil, err
-		}
 	case "socks5h":
-		dialer, err = fasthttpSocksDialerDualStackTimeout(ctx, proxyURL, timeout, false)
+		return fasthttpSocksDialer(ctx, proxyURL, false)
-		if err != nil {
-			return nil, err
-		}
 	case "http":
-		dialer = fasthttpproxy.FasthttpHTTPDialerDualStackTimeout(proxyURL.String(), timeout)
+		return fasthttpConnectDialer(proxyURL, false), nil
 	case "https":
-		dialer = fasthttpHTTPSDialerDualStackTimeout(proxyURL, timeout)
+		return fasthttpConnectDialer(proxyURL, true), nil
 	default:
 		return nil, types.NewProxyUnsupportedSchemeError(proxyURL.Scheme)
 	}
-
-	return dialer, nil
 }
 
-// The returned dial function can return the following errors:
+// fasthttpSocksDialer creates a SOCKS5 dial function that takes the timeout per call.
+// It can return the following errors:
+//   - types.ErrProxyNoContextDialer
 //   - types.ProxyDialError
-func fasthttpSocksDialerDualStackTimeout(ctx context.Context, proxyURL *url.URL, timeout time.Duration, resolveLocally bool) (fasthttp.DialFunc, error) {
+func fasthttpSocksDialer(ctx context.Context, proxyURL *url.URL, resolveLocally bool) (fasthttp.DialFuncWithTimeout, error) {
 	netDialer := &net.Dialer{}
 
 	// Parse auth from proxy URL if present
@@ -149,66 +154,92 @@ func fasthttpSocksDialerDualStackTimeout(ctx context.Context, proxyURL *url.URL,
 
 	proxyStr := proxyURL.String()
 
-	// Assert to ContextDialer for timeout support
+	// Timeouts need DialContext, which proxy.SOCKS5 always provides with a net.Dialer.
 	contextDialer, ok := socksDialer.(proxy.ContextDialer)
 	if !ok {
-		// Fallback without timeout (should not happen with net.Dialer)
+		return nil, types.ErrProxyNoContextDialer
-		return func(addr string) (net.Conn, error) {
-			conn, err := socksDialer.Dial("tcp", addr)
-			if err != nil {
-				return nil, types.NewProxyDialError(proxyStr, err)
-			}
-			return conn, nil
-		}, nil
 	}
 
 	// Return dial function that uses context with timeout
-	return func(addr string) (net.Conn, error) {
+	return func(addr string, timeout time.Duration) (net.Conn, error) {
 		deadline := time.Now().Add(timeout)
 
+		addrs := []string{addr}
 		if resolveLocally {
-			host, port, err := net.SplitHostPort(addr)
+			var err error
+			addrs, err = resolveIPv4First(ctx, addr, timeout)
 			if err != nil {
 				return nil, types.NewProxyDialError(proxyStr, err)
 			}
+		}
 
-			dnsCtx, dnsCancel := context.WithTimeout(ctx, timeout)
+		// Try every resolved address, so one unreachable family does not fail the dial.
-			ips, err := net.DefaultResolver.LookupIP(dnsCtx, "ip", host)
+		var lastErr error
-			dnsCancel()
+		for _, candidate := range addrs {
-			if err != nil {
+			remaining := time.Until(deadline)
-				return nil, types.NewProxyDialError(proxyStr, err)
+			if remaining <= 0 {
-			}
+				return nil, types.NewProxyDialError(proxyStr, context.DeadlineExceeded)
-			if len(ips) == 0 {
-				return nil, types.NewProxyDialError(proxyStr, types.NewProxyResolveError(host))
 			}
 
-			// Use the first resolved IP
+			dialCtx, dialCancel := context.WithTimeout(ctx, remaining)
-			addr = net.JoinHostPort(ips[0].String(), port)
+			conn, err := contextDialer.DialContext(dialCtx, "tcp", candidate)
+			dialCancel()
+			if err == nil {
+				return conn, nil
+			}
+			lastErr = err
 		}
-
+		return nil, types.NewProxyDialError(proxyStr, lastErr)
-		// Use remaining time for dial
-		remaining := time.Until(deadline)
-		if remaining <= 0 {
-			return nil, types.NewProxyDialError(proxyStr, context.DeadlineExceeded)
-		}
-
-		dialCtx, dialCancel := context.WithTimeout(ctx, remaining)
-		defer dialCancel()
-
-		conn, err := contextDialer.DialContext(dialCtx, "tcp", addr)
-		if err != nil {
-			return nil, types.NewProxyDialError(proxyStr, err)
-		}
-		return conn, nil
 	}, nil
 }
 
+// resolveIPv4First resolves the host of addr into candidate addresses, IPv4 ones first.
+// It can return the following errors:
+//   - types.ProxyResolveError
+func resolveIPv4First(ctx context.Context, addr string, timeout time.Duration) ([]string, error) {
+	host, port, err := net.SplitHostPort(addr)
+	if err != nil {
+		return nil, err
+	}
+
+	dnsCtx, dnsCancel := context.WithTimeout(ctx, timeout)
+	ips, err := net.DefaultResolver.LookupIP(dnsCtx, "ip", host)
+	dnsCancel()
+	if err != nil {
+		return nil, err
+	}
+	if len(ips) == 0 {
+		return nil, types.NewProxyResolveError(host)
+	}
+
+	addrs := make([]string, 0, len(ips))
+	for _, ip := range ips {
+		if ip.To4() != nil {
+			addrs = append(addrs, net.JoinHostPort(ip.String(), port))
+		}
+	}
+	for _, ip := range ips {
+		if ip.To4() == nil {
+			addrs = append(addrs, net.JoinHostPort(ip.String(), port))
+		}
+	}
+	return addrs, nil
+}
+
+// fasthttpConnectDialer creates a dial function that tunnels through an HTTP proxy with CONNECT,
+// reaching the proxy over TLS when useTLS is set.
+//
 // The returned dial function can return the following errors:
 //   - types.ProxyDialError
-func fasthttpHTTPSDialerDualStackTimeout(proxyURL *url.URL, timeout time.Duration) fasthttp.DialFunc {
+func fasthttpConnectDialer(proxyURL *url.URL, useTLS bool) fasthttp.DialFuncWithTimeout {
+	defaultPort := "80"
+	if useTLS {
+		defaultPort = "443"
+	}
+
 	proxyAddr := proxyURL.Host
 	if proxyURL.Port() == "" {
-		proxyAddr = net.JoinHostPort(proxyURL.Hostname(), "443")
+		proxyAddr = net.JoinHostPort(proxyURL.Hostname(), defaultPort)
 	}
 
 	// Build Proxy-Authorization header if auth is present
@@ -222,7 +253,7 @@ func fasthttpHTTPSDialerDualStackTimeout(proxyURL *url.URL, timeout time.Duratio
 
 	proxyStr := proxyURL.String()
 
-	return func(addr string) (net.Conn, error) {
+	return func(addr string, timeout time.Duration) (net.Conn, error) {
 		// Establish TCP connection to proxy with timeout
 		start := time.Now()
 		conn, err := fasthttp.DialDualStackTimeout(proxyAddr, timeout)
@@ -242,13 +273,15 @@ func fasthttpHTTPSDialerDualStackTimeout(proxyURL *url.URL, timeout time.Duratio
 			return nil, types.NewProxyDialError(proxyStr, err)
 		}
 
-		// Upgrade to TLS
+		if useTLS {
-		tlsConn := tls.Client(conn, &tls.Config{
+			tlsConn := tls.Client(conn, &tls.Config{
-			ServerName: proxyURL.Hostname(),
+				ServerName: proxyURL.Hostname(),
-		})
+			})
-		if err := tlsConn.Handshake(); err != nil {
+			if err := tlsConn.Handshake(); err != nil {
-			tlsConn.Close() //nolint:errcheck,gosec
+				tlsConn.Close() //nolint:errcheck,gosec
-			return nil, types.NewProxyDialError(proxyStr, err)
+				return nil, types.NewProxyDialError(proxyStr, err)
+			}
+			conn = tlsConn
 		}
 
 		// Build and send CONNECT request
@@ -262,35 +295,35 @@ func fasthttpHTTPSDialerDualStackTimeout(proxyURL *url.URL, timeout time.Duratio
 			connectReq.Header.Set("Proxy-Authorization", proxyAuth)
 		}
 
-		if err := connectReq.Write(tlsConn); err != nil {
+		if err := connectReq.Write(conn); err != nil {
-			tlsConn.Close() //nolint:errcheck,gosec
+			conn.Close() //nolint:errcheck,gosec
 			return nil, types.NewProxyDialError(proxyStr, err)
 		}
 
 		// Read response using buffered reader, but return wrapped connection
 		// to preserve any buffered data
-		bufReader := bufio.NewReader(tlsConn)
+		bufReader := bufio.NewReader(conn)
 		resp, err := http.ReadResponse(bufReader, connectReq)
 		if err != nil {
-			tlsConn.Close() //nolint:errcheck,gosec
+			conn.Close() //nolint:errcheck,gosec
 			return nil, types.NewProxyDialError(proxyStr, err)
 		}
 		resp.Body.Close() //nolint:errcheck,gosec
 
 		if resp.StatusCode != http.StatusOK {
-			tlsConn.Close() //nolint:errcheck,gosec
+			conn.Close() //nolint:errcheck,gosec
 			return nil, types.NewProxyDialError(proxyStr, types.NewProxyConnectError(resp.Status))
 		}
 
 		// Clear deadline for the tunneled connection
-		if err := tlsConn.SetDeadline(time.Time{}); err != nil {
+		if err := conn.SetDeadline(time.Time{}); err != nil {
-			tlsConn.Close() //nolint:errcheck,gosec
+			conn.Close() //nolint:errcheck,gosec
 			return nil, types.NewProxyDialError(proxyStr, err)
 		}
 
 		// Return wrapped connection that uses the buffered reader
 		// to avoid losing any data that was read ahead
-		return &bufferedConn{Conn: tlsConn, reader: bufReader}, nil
+		return &bufferedConn{Conn: conn, reader: bufReader}, nil
 	}
 }
 
@@ -306,18 +339,10 @@ func (c *bufferedConn) Read(b []byte) (int, error) {
 	return c.reader.Read(b)
 }
 
-func NewHostClientGenerator(clients ...*fasthttp.HostClient) HostClientGenerator {
+func newClientIndexGenerator(count int) clientIndexGenerator {
-	switch len(clients) {
+	indexes := make([]int, count)
-	case 0:
+	for i := range indexes {
-		hostClient := &fasthttp.HostClient{}
+		indexes[i] = i
-		return func() *fasthttp.HostClient {
-			return hostClient
-		}
-	case 1:
-		return func() *fasthttp.HostClient {
-			return clients[0]
-		}
-	default:
-		return utilsSlice.RandomCycle(nil, clients...)
 	}
+	return utilsSlice.RandomCycle(nil, indexes...)
 }

internal/sarin/filecache.go

@@ -58,8 +58,7 @@ func (fc *FileCache) GetOrLoad(source string) (*CachedFile, error) {
 
 	file := &CachedFile{Content: content, Filename: filename}
 
-	// LoadOrStore handles race condition - if another goroutine
+	// If another goroutine cached it first, LoadOrStore returns theirs
-	// cached it first, we get theirs (no duplicate storage)
 	actual, _ := fc.cache.LoadOrStore(source, file)
 	return actual.(*CachedFile), nil
 }
@@ -94,10 +93,18 @@ func (fc *FileCache) fetchURL(url string) ([]byte, string, error) {
 		return nil, "", types.NewHTTPStatusError(url, resp.StatusCode, resp.Status)
 	}
 
-	content, err := io.ReadAll(resp.Body)
+	// A declared size above the limit is refused before anything is read.
+	if resp.ContentLength > types.RemoteFetchLimit {
+		return nil, "", types.NewHTTPFetchError(url, types.ErrRemoteFileTooLarge)
+	}
+
+	content, err := io.ReadAll(io.LimitReader(resp.Body, types.RemoteFetchLimit+1))
 	if err != nil {
 		return nil, "", types.NewHTTPFetchError(url, err)
 	}
+	if len(content) > types.RemoteFetchLimit {
+		return nil, "", types.NewHTTPFetchError(url, types.ErrRemoteFileTooLarge)
+	}
 
 	// Extract filename from URL path
 	filename := path.Base(url)

internal/sarin/helpers.go

@@ -1,6 +1,7 @@
 package sarin
 
 import (
+	"math"
 	"math/rand/v2"
 	"time"
 )
@@ -19,3 +20,17 @@ func firstOrEmpty(values []string) string {
 	}
 	return values[0]
 }
+
+func safeUintToInt(u uint) int {
+	if u > math.MaxInt {
+		return math.MaxInt
+	}
+	return int(u)
+}
+
+func safeUint64ToInt(u uint64) int {
+	if u > math.MaxInt {
+		return math.MaxInt
+	}
+	return int(u)
+}

internal/sarin/request.go

@@ -56,9 +56,9 @@ func NewRequestGenerator(
 
 	pathGenerator, isPathGeneratorDynamic := createTemplateFunc(requestURL.Path, lazyTemplateRoot)
 	methodGenerator, isMethodGeneratorDynamic := NewMethodGeneratorFunc(localRand, methods, lazyTemplateRoot)
-	paramsGenerator, isParamsGeneratorDynamic := NewParamsGeneratorFunc(localRand, params, lazyTemplateRoot)
+	paramsGenerator, isParamsGeneratorDynamic, paramKeysAreStatic := NewParamsGeneratorFunc(localRand, params, lazyTemplateRoot)
-	headersGenerator, isHeadersGeneratorDynamic := NewHeadersGeneratorFunc(localRand, headers, lazyTemplateRoot)
+	headersGenerator, isHeadersGeneratorDynamic, headerKeysAreStatic := NewHeadersGeneratorFunc(localRand, headers, lazyTemplateRoot)
-	cookiesGenerator, isCookiesGeneratorDynamic := NewCookiesGeneratorFunc(localRand, cookies, lazyTemplateRoot)
+	cookiesGenerator, isCookiesGeneratorDynamic, cookieKeysAreStatic := NewCookiesGeneratorFunc(localRand, cookies, lazyTemplateRoot)
 
 	bodyTemplateFuncMapData := &BodyTemplateFuncMapData{}
 	var bodyTemplateRoot *template.Template
@@ -83,13 +83,26 @@ func NewRequestGenerator(
 		Cookies: make(map[string][]string),
 	}
 
+	// When a map's key set is fixed, every request refills exactly the same keys, so
+	// the value slices can be truncated and reused instead of being reallocated after
+	// a clear(). Scripts are excluded: they may swap the maps out or add keys of their
+	// own, and they would observe a leftover empty slice where a key used to be absent.
+	reuseParamSlices := paramKeysAreStatic && !hasScripts
+	reuseHeaderSlices := headerKeysAreStatic && !hasScripts
+	reuseCookieSlices := cookieKeysAreStatic && !hasScripts
+
 	var (
 		data valuesData
 		path string
 		err  error
 	)
 	return func(req *fasthttp.Request) error {
-			resetRequestData(reqData)
+			resetStringSliceMap(reqData.Headers, reuseHeaderSlices)
+			resetStringSliceMap(reqData.Params, reuseParamSlices)
+			resetStringSliceMap(reqData.Cookies, reuseCookieSlices)
+			reqData.Method = ""
+			reqData.Path = ""
+			reqData.Body = ""
 
 			data, err = valuesGenerator()
 			if err != nil {
@@ -143,20 +156,24 @@ func NewRequestGenerator(
 			hasScripts
 }
 
-func resetRequestData(reqData *script.RequestData) {
+// resetStringSliceMap empties m for the next render. With reuse it truncates the
-	reqData.Method = ""
+// value slices in place so the following appends land in the existing backing
-	reqData.Path = ""
+// arrays, without it the map is cleared so no stale key can survive.
-	reqData.Body = ""
+func resetStringSliceMap(m map[string][]string, reuse bool) {
-	clear(reqData.Headers)
+	if !reuse {
-	clear(reqData.Params)
+		clear(m)
-	clear(reqData.Cookies)
+		return
+	}
+	for k, v := range m {
+		m[k] = v[:0]
+	}
 }
 
 func applyRequestDataToFastHTTP(reqData *script.RequestData, req *fasthttp.Request, host, scheme string) {
 	req.Header.SetHost(host)
 	req.SetRequestURI(reqData.Path)
 	req.Header.SetMethod(reqData.Method)
-	req.SetBody([]byte(reqData.Body))
+	req.SetBodyString(reqData.Body)
 
 	for k, values := range reqData.Headers {
 		for _, v := range values {
@@ -164,20 +181,17 @@ func applyRequestDataToFastHTTP(reqData *script.RequestData, req *fasthttp.Reque
 		}
 	}
 
-	for k, values := range reqData.Params {
+	if len(reqData.Params) > 0 {
-		for _, v := range values {
+		args := req.URI().QueryArgs()
-			req.URI().QueryArgs().Add(k, v)
+		for k, values := range reqData.Params {
+			for _, v := range values {
+				args.Add(k, v)
+			}
 		}
 	}
 
 	if len(reqData.Cookies) > 0 {
-		cookieStrings := make([]string, 0, len(reqData.Cookies))
+		req.Header.Add("Cookie", cookieHeaderValue(reqData.Cookies))
-		for k, values := range reqData.Cookies {
-			for _, v := range values {
-				cookieStrings = append(cookieStrings, k+"="+v)
-			}
-		}
-		req.Header.Add("Cookie", strings.Join(cookieStrings, "; "))
 	}
 
 	if scheme == "https" {
@@ -185,6 +199,22 @@ func applyRequestDataToFastHTTP(reqData *script.RequestData, req *fasthttp.Reque
 	}
 }
 
+// cookieHeaderValue joins cookies into a single Cookie header value ("a=1; b=2").
+func cookieHeaderValue(cookies map[string][]string) string {
+	var sb strings.Builder
+	for k, values := range cookies {
+		for _, v := range values {
+			if sb.Len() > 0 {
+				sb.WriteString("; ")
+			}
+			sb.WriteString(k)
+			sb.WriteByte('=')
+			sb.WriteString(v)
+		}
+	}
+	return sb.String()
+}
+
 func NewMethodGeneratorFunc(localRand *rand.Rand, methods []string, lazyRoot func() *template.Template) (requestDataGenerator, bool) {
 	methodGenerator, isDynamic := buildStringSliceGenerator(localRand, methods, lazyRoot)
 
@@ -221,8 +251,8 @@ func NewBodyGeneratorFunc(localRand *rand.Rand, bodies []string, lazyRoot func()
 	}, isDynamic
 }
 
-func NewParamsGeneratorFunc(localRand *rand.Rand, params types.Params, lazyRoot func() *template.Template) (requestDataGenerator, bool) {
+func NewParamsGeneratorFunc(localRand *rand.Rand, params types.Params, lazyRoot func() *template.Template) (requestDataGenerator, bool, bool) {
-	generators, isDynamic := buildKeyValueGenerators(localRand, params, lazyRoot)
+	generators, isDynamic, keysAreStatic := buildKeyValueGenerators(localRand, params, lazyRoot)
 
 	var (
 		key, value string
@@ -243,11 +273,11 @@ func NewParamsGeneratorFunc(localRand *rand.Rand, params types.Params, lazyRoot
 			reqData.Params[key] = append(reqData.Params[key], value)
 		}
 		return nil
-	}, isDynamic
+	}, isDynamic, keysAreStatic
 }
 
-func NewHeadersGeneratorFunc(localRand *rand.Rand, headers types.Headers, lazyRoot func() *template.Template) (requestDataGenerator, bool) {
+func NewHeadersGeneratorFunc(localRand *rand.Rand, headers types.Headers, lazyRoot func() *template.Template) (requestDataGenerator, bool, bool) {
-	generators, isDynamic := buildKeyValueGenerators(localRand, headers, lazyRoot)
+	generators, isDynamic, keysAreStatic := buildKeyValueGenerators(localRand, headers, lazyRoot)
 
 	var (
 		key, value string
@@ -268,11 +298,11 @@ func NewHeadersGeneratorFunc(localRand *rand.Rand, headers types.Headers, lazyRo
 			reqData.Headers[key] = append(reqData.Headers[key], value)
 		}
 		return nil
-	}, isDynamic
+	}, isDynamic, keysAreStatic
 }
 
-func NewCookiesGeneratorFunc(localRand *rand.Rand, cookies types.Cookies, lazyRoot func() *template.Template) (requestDataGenerator, bool) {
+func NewCookiesGeneratorFunc(localRand *rand.Rand, cookies types.Cookies, lazyRoot func() *template.Template) (requestDataGenerator, bool, bool) {
-	generators, isDynamic := buildKeyValueGenerators(localRand, cookies, lazyRoot)
+	generators, isDynamic, keysAreStatic := buildKeyValueGenerators(localRand, cookies, lazyRoot)
 
 	var (
 		key, value string
@@ -293,14 +323,26 @@ func NewCookiesGeneratorFunc(localRand *rand.Rand, cookies types.Cookies, lazyRo
 			reqData.Cookies[key] = append(reqData.Cookies[key], value)
 		}
 		return nil
-	}, isDynamic
+	}, isDynamic, keysAreStatic
 }
 
 func NewValuesGeneratorFunc(values []string, lazyRoot func() *template.Template) func() (valuesData, error) {
+	// No values configured: hand back one shared empty map instead of allocating a
+	// fresh one for every request. Nothing ever writes to it.
+	if len(values) == 0 {
+		empty := valuesData{Values: map[string]string{}}
+		return func() (valuesData, error) { return empty, nil }
+	}
+
 	generators := make([]func(_ any) (string, error), len(values))
 
+	isDynamic := false
 	for i, v := range values {
-		generators[i], _ = createTemplateFunc(v, lazyRoot)
+		var valueIsDynamic bool
+		generators[i], valueIsDynamic = createTemplateFunc(v, lazyRoot)
+		if valueIsDynamic {
+			isDynamic = true
+		}
 	}
 
 	var (
@@ -308,7 +350,7 @@ func NewValuesGeneratorFunc(values []string, lazyRoot func() *template.Template)
 		data     map[string]string
 		err      error
 	)
-	return func() (valuesData, error) {
+	generate := func() (valuesData, error) {
 		result := make(map[string]string)
 		for _, generator := range generators {
 			rendered, err = generator(nil)
@@ -326,6 +368,15 @@ func NewValuesGeneratorFunc(values []string, lazyRoot func() *template.Template)
 
 		return valuesData{Values: result}, nil
 	}
+
+	// Every value is a literal, so the parsed result is identical on every request:
+	// render and parse once instead of re-running godotenv per request.
+	if !isDynamic {
+		staticResult, staticErr := generate()
+		return func() (valuesData, error) { return staticResult, staticErr }
+	}
+
+	return generate
 }
 
 func createTemplateFunc(value string, lazyRoot func() *template.Template) (func(data any) (string, error), bool) {
@@ -335,15 +386,19 @@ func createTemplateFunc(value string, lazyRoot func() *template.Template) (func(
 
 	tmpl, err := lazyRoot().New("").Parse(value)
 	if err == nil && hasTemplateActions(tmpl) {
-		var err error
+		var (
+			buf bytes.Buffer
+			err error
+		)
 		return func(data any) (string, error) {
-			var buf bytes.Buffer
+			buf.Reset()
 			if err = tmpl.Execute(&buf, data); err != nil {
 				return "", types.NewTemplateRenderError(err)
 			}
 			return buf.String(), nil
 		}, true
 	}
+
 	return func(_ any) (string, error) { return value, nil }, false
 }
 
@@ -360,8 +415,9 @@ func buildKeyValueGenerators[T keyValueItem](
 	localRand *rand.Rand,
 	items []T,
 	lazyRoot func() *template.Template,
-) ([]keyValueGenerator, bool) {
+) ([]keyValueGenerator, bool, bool) {
 	isDynamic := false
+	keysAreStatic := true
 	generators := make([]keyValueGenerator, len(items))
 
 	for generatorIndex, item := range items {
@@ -372,6 +428,7 @@ func buildKeyValueGenerators[T keyValueItem](
 		keyFunc, keyIsDynamic := createTemplateFunc(keyValue.Key, lazyRoot)
 		if keyIsDynamic {
 			isDynamic = true
+			keysAreStatic = false
 		}
 
 		// Generate value functions
@@ -394,7 +451,7 @@ func buildKeyValueGenerators[T keyValueItem](
 		}
 	}
 
-	return generators, isDynamic
+	return generators, isDynamic, keysAreStatic
 }
 
 func buildStringSliceGenerator(

internal/sarin/response.go

@@ -2,7 +2,6 @@ package sarin
 
 import (
 	"encoding/json"
-	"fmt"
 	"math/big"
 	"os"
 	"slices"
@@ -10,14 +9,22 @@ import (
 	"sync"
 	"time"
 
-	"github.com/charmbracelet/lipgloss"
+	"charm.land/lipgloss/v2"
-	"github.com/charmbracelet/lipgloss/table"
+	"charm.land/lipgloss/v2/table"
 	"go.yaml.in/yaml/v4"
 )
 
 const DefaultResponseDurationAccuracy uint32 = 1
 const DefaultResponseColumnMaxWidth = 50
 
+// maxResponseKeys bounds the distinct response keys, so error messages carrying
+// per-request text cannot grow the map without limit. It stays above the number of
+// HTTP status codes, so real ones are never merged.
+const maxResponseKeys = 1000
+
+// otherResponseKey collects everything that arrives after the key limit is reached.
+const otherResponseKey = "other"
+
 // Duration wraps time.Duration to provide consistent JSON/YAML marshaling as human-readable strings.
 type Duration time.Duration
 
@@ -96,6 +103,11 @@ func (data *SarinResponseData) Add(responseKey string, responseTime time.Duratio
 	defer data.Unlock()
 
 	response, ok := data.Responses[responseKey]
+	if !ok && len(data.Responses) >= maxResponseKeys {
+		responseKey = otherResponseKey
+		response, ok = data.Responses[responseKey]
+	}
+
 	if !ok {
 		data.Responses[responseKey] = &Response{
 			durations: map[time.Duration]uint64{
@@ -159,7 +171,7 @@ func (data *SarinResponseData) PrintTable() {
 			return cellStyle
 		})
 
-	fmt.Println(tbl)
+	lipgloss.Println(tbl)
 }
 
 func (data *SarinResponseData) PrintJSON() {

internal/sarin/runner.go

@@ -2,8 +2,13 @@ package sarin
 
 import (
 	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"log"
 	"net/url"
 	"os"
+	"strings"
 	"sync"
 	"sync/atomic"
 	"time"
@@ -14,20 +19,165 @@ import (
 	"go.aykhans.me/sarin/internal/types"
 )
 
-type runtimeMessageLevel uint8
+type runtimeLogLevel uint8
 
 const (
-	runtimeMessageLevelWarning runtimeMessageLevel = iota
+	runtimeLogLevelInfo runtimeLogLevel = iota
-	runtimeMessageLevelError
+	runtimeLogLevelError
 )
 
-type runtimeMessage struct {
+type runtimeLog struct {
 	timestamp time.Time
-	level     runtimeMessageLevel
+	level     runtimeLogLevel
 	text      string
 }
 
-type messageSender func(level runtimeMessageLevel, text string)
+type runtimeLogger func(level runtimeLogLevel, text string)
+
+// SplitLogLevels parses a comma-separated log-level string into a deduplicated
+// slice of level tokens (surrounding whitespace trimmed, empties dropped). Level
+// names are matched case-sensitively, like the other enum options.
+func SplitLogLevels(levels string) []string {
+	var out []string
+	seen := make(map[string]bool)
+	for part := range strings.SplitSeq(levels, ",") {
+		token := strings.TrimSpace(part)
+		if token == "" || seen[token] {
+			continue
+		}
+		seen[token] = true
+		out = append(out, token)
+	}
+	return out
+}
+
+// IsInteractiveTerminal reports whether fd is a terminal that can actually be
+// drawn on. A pty reports as a terminal even while its size is still zero, and
+// Bubble Tea paints into a width x height cell buffer, so a zero dimension
+// renders nothing at all.
+func IsInteractiveTerminal(fd uintptr) bool {
+	if !term.IsTerminal(fd) {
+		return false
+	}
+	width, height, err := term.GetSize(fd)
+	return err == nil && width > 0 && height > 0
+}
+
+// respLogger logs a single completed response.
+type respLogger func(duration time.Duration, resp *fasthttp.Response)
+
+func noopLog(runtimeLogLevel, string)               {}
+func noopRespLog(time.Duration, *fasthttp.Response) {}
+
+// gateSendLog wraps emit with level filtering decided once from the enabled
+// levels. It stays general (any level filters correctly) while avoiding a
+// per-log check when both levels are on and any work at all when both are off.
+func gateSendLog(logInfo, logError bool, emit func(level runtimeLogLevel, text string)) runtimeLogger {
+	switch {
+	case logInfo && logError:
+		return emit
+	case logInfo:
+		return func(level runtimeLogLevel, text string) {
+			if level == runtimeLogLevelInfo {
+				emit(level, text)
+			}
+		}
+	case logError:
+		return func(level runtimeLogLevel, text string) {
+			if level == runtimeLogLevelError {
+				emit(level, text)
+			}
+		}
+	default:
+		return noopLog
+	}
+}
+
+// respBodySnippetLen bounds how many bytes of the body the compact (TUI)
+// rendering shows.
+const respBodySnippetLen = 100
+
+// formatRuntimeLogLine renders a runtime log as a plain (unstyled) line for
+// stderr output. ANSI styling is left to the TUI.
+func formatRuntimeLogLine(timestamp time.Time, level runtimeLogLevel, text string) string {
+	levelStr := "ERROR"
+	if level == runtimeLogLevelInfo {
+		levelStr = "INFO"
+	}
+	return "[" + timestamp.Format("15:04:05") + "] " + levelStr + ": " + text
+}
+
+// respToLog renders a response as a compact one-line summary for the TUI log box
+// (the "[time] INFO:" prefix is added by the TUI).
+func respToLog(duration time.Duration, resp *fasthttp.Response) string {
+	var sb strings.Builder
+	sb.WriteString(statusCodeToString(resp.StatusCode()))
+	sb.WriteString(" ")
+	sb.WriteString(Duration(duration).String())
+	if snippet := bodySnippet(resp.Body(), respBodySnippetLen); snippet != "" {
+		sb.WriteString(" | ")
+		sb.WriteString(snippet)
+	}
+	return sb.String()
+}
+
+type respLogEntry struct {
+	Status   int                 `json:"status"`
+	Duration string              `json:"duration"`
+	Headers  map[string][]string `json:"headers,omitempty"`
+	Body     string              `json:"body,omitempty"`
+}
+
+// respToLogJSON renders a response as a single, self-contained JSON line so the
+// stderr stream stays valid NDJSON (pipeable to jq or any consumer).
+func respToLogJSON(duration time.Duration, resp *fasthttp.Response) string {
+	entry := respLogEntry{
+		Status:   resp.StatusCode(),
+		Duration: Duration(duration).String(),
+		Headers:  collectRespHeaders(resp),
+		Body:     string(resp.Body()),
+	}
+	data, err := json.Marshal(entry)
+	if err != nil {
+		return `{"error":"failed to marshal response log"}`
+	}
+	return string(data)
+}
+
+func collectRespHeaders(resp *fasthttp.Response) map[string][]string {
+	headers := make(map[string][]string)
+	for key, value := range resp.Header.All() {
+		k := string(key)
+		headers[k] = append(headers[k], string(value))
+	}
+	return headers
+}
+
+// bodySnippet returns the first maxLen bytes of body collapsed onto a single
+// line (control characters replaced with spaces), with an ellipsis when truncated.
+func bodySnippet(body []byte, maxLen int) string {
+	if len(body) == 0 {
+		return ""
+	}
+
+	truncated := false
+	if len(body) > maxLen {
+		body = body[:maxLen]
+		truncated = true
+	}
+
+	s := strings.Map(func(r rune) rune {
+		if r == '\n' || r == '\r' || r == '\t' {
+			return ' '
+		}
+		return r
+	}, string(body))
+
+	if truncated {
+		s += "..."
+	}
+	return s
+}
 
 type sarin struct {
 	workers        uint
@@ -40,16 +190,24 @@ type sarin struct {
 	totalRequests  *uint64
 	totalDuration  *time.Duration
 	timeout        time.Duration
-	quiet          bool
+	showProgress   bool
 	skipCertVerify bool
 	values         []string
 	collectStats   bool
 	dryRun         bool
+	logInfo        bool
+	logError       bool
+	logFile        string
 
-	hostClients []*fasthttp.HostClient
+	// jobsCtx ends the run, either when the duration expires or on Ctrl+C.
-	responses   *SarinResponseData
+	jobsCtx    context.Context //nolint:containedctx
-	fileCache   *FileCache
+	jobsCancel context.CancelFunc
-	scriptChain *script.Chain
+
+	hostClients       []*fasthttp.HostClient
+	scriptHTTPClients []*scriptHTTPClient
+	responses         *SarinResponseData
+	fileCache         *FileCache
+	scriptChain       *script.Chain
 }
 
 // NewSarin creates a new sarin instance for load testing.
@@ -65,8 +223,9 @@ func NewSarin(
 	workers uint,
 	totalRequests *uint64,
 	totalDuration *time.Duration,
-	quiet bool,
+	showProgress bool,
 	skipCertVerify bool,
+	maxResponseBody uint64,
 	params types.Params,
 	headers types.Headers,
 	cookies types.Cookies,
@@ -75,6 +234,8 @@ func NewSarin(
 	values []string,
 	collectStats bool,
 	dryRun bool,
+	logLevel string,
+	logFile string,
 	luaScripts []string,
 	jsScripts []string,
 ) (*sarin, error) {
@@ -82,7 +243,23 @@ func NewSarin(
 		workers = 1
 	}
 
-	hostClients, err := newHostClients(ctx, timeout, proxies, workers, requestURL, skipCertVerify)
+	// Resolve which log levels are enabled once, up front.
+	var logInfo, logError bool
+	for _, level := range SplitLogLevels(logLevel) {
+		switch level {
+		case "info":
+			logInfo = true
+		case "error":
+			logError = true
+		}
+	}
+
+	proxyURLs := make([]url.URL, len(proxies))
+	for i, proxy := range proxies {
+		proxyURLs[i] = url.URL(proxy)
+	}
+
+	hostClients, err := NewHostClients(ctx, timeout, proxyURLs, workers, requestURL, skipCertVerify, maxResponseBody)
 	if err != nil {
 		return nil, err
 	}
@@ -100,25 +277,42 @@ func NewSarin(
 
 	scriptChain := script.NewChain(luaSources, jsSources)
 
+	jobsCtx, jobsCancel := context.WithCancel(ctx)
+
+	var scriptHTTPClients []*scriptHTTPClient
+	if !scriptChain.IsEmpty() {
+		scriptHTTPClients, err = newScriptHTTPClients(jobsCtx, proxyURLs, workers, maxResponseBody)
+		if err != nil {
+			jobsCancel()
+			return nil, err
+		}
+	}
+
 	srn := &sarin{
-		workers:        workers,
+		jobsCtx:           jobsCtx,
-		requestURL:     requestURL,
+		jobsCancel:        jobsCancel,
-		methods:        methods,
+		workers:           workers,
-		params:         params,
+		requestURL:        requestURL,
-		headers:        headers,
+		methods:           methods,
-		cookies:        cookies,
+		params:            params,
-		bodies:         bodies,
+		headers:           headers,
-		totalRequests:  totalRequests,
+		cookies:           cookies,
-		totalDuration:  totalDuration,
+		bodies:            bodies,
-		timeout:        timeout,
+		totalRequests:     totalRequests,
-		quiet:          quiet,
+		totalDuration:     totalDuration,
-		skipCertVerify: skipCertVerify,
+		timeout:           timeout,
-		values:         values,
+		showProgress:      showProgress,
-		collectStats:   collectStats,
+		skipCertVerify:    skipCertVerify,
-		dryRun:         dryRun,
+		values:            values,
-		hostClients:    hostClients,
+		collectStats:      collectStats,
-		fileCache:      NewFileCache(time.Second * 10),
+		dryRun:            dryRun,
-		scriptChain:    scriptChain,
+		logInfo:           logInfo,
+		logError:          logError,
+		logFile:           logFile,
+		hostClients:       hostClients,
+		scriptHTTPClients: scriptHTTPClients,
+		fileCache:         NewFileCache(time.Second * 30),
+		scriptChain:       scriptChain,
 	}
 
 	if collectStats {
@@ -128,73 +322,92 @@ func NewSarin(
 	return srn, nil
 }
 
-func (q sarin) GetResponses() *SarinResponseData {
+func (s sarin) GetResponses() *SarinResponseData {
-	return q.responses
+	return s.responses
 }
 
-func (q sarin) Start(ctx context.Context, stopCtrl *StopController) {
+func (s sarin) Start(stopCtrl *StopController) {
-	jobsCtx, jobsCancel := context.WithCancel(ctx)
-
 	var workersWG sync.WaitGroup
-	jobsCh := make(chan struct{}, max(q.workers, 1))
+	jobsCh := make(chan struct{}, max(s.workers, 1))
 
 	var counter atomic.Uint64
 
 	totalRequests := uint64(0)
-	if q.totalRequests != nil {
+	if s.totalRequests != nil {
-		totalRequests = *q.totalRequests
+		totalRequests = *s.totalRequests
 	}
 
-	var streamCtx context.Context
+	onTerminal := IsInteractiveTerminal(os.Stdout.Fd())
-	var streamCancel context.CancelFunc
+	// The progress bar needs an interactive terminal to render.
-	var streamCh chan struct{}
+	showProgressBar := s.showProgress && onTerminal
-	var messageChannel chan runtimeMessage
+	// The bubbletea TUI hosts the bar and/or the live log box, so it runs whenever
-	var sendMessage messageSender
+	// either has something to show: the bar, or logs that would land in the box
+	// (i.e. logs are enabled and not redirected to a file).
+	runTUI := showProgressBar || (onTerminal && (s.logInfo || s.logError) && s.logFile == "")
 
-	if !q.quiet && !term.IsTerminal(os.Stdout.Fd()) {
+	// Open the log file up front, before registering any defer, so a bad path
-		q.quiet = true
+	// exits cleanly.
+	var logFile *os.File
+	if s.logFile != "" {
+		f, err := os.OpenFile(s.logFile, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, 0o600)
+		if err != nil {
+			fmt.Fprintln(os.Stderr, "failed to open log file "+s.logFile+": "+err.Error())
+			os.Exit(1)
+		}
+		defer f.Close() //nolint:errcheck
+		logFile = f
 	}
 
-	if q.quiet {
+	var (
-		sendMessage = func(level runtimeMessageLevel, text string) {}
+		streamCtx     context.Context
-	} else {
+		streamCancel  context.CancelFunc
+		streamCh      chan struct{}
+		tuiLogChannel chan runtimeLog
+	)
+	if runTUI {
 		streamCtx, streamCancel = context.WithCancel(context.Background())
 		defer streamCancel()
 		streamCh = make(chan struct{})
-		messageChannel = make(chan runtimeMessage, max(q.workers, 1))
+		tuiLogChannel = make(chan runtimeLog, max(s.workers, 1))
-		sendMessage = func(level runtimeMessageLevel, text string) {
+	}
-			messageChannel <- runtimeMessage{
+
-				timestamp: time.Now(),
+	// Route logs: to the file if given, else to the TUI log box while it runs,
-				level:     level,
+	// otherwise to stderr.
-				text:      text,
+	var (
-			}
+		sendLog     runtimeLogger
-		}
+		sendRespLog respLogger
+	)
+	switch {
+	case logFile != nil:
+		sendLog, sendRespLog = s.newWriterLog(logFile)
+	case runTUI:
+		sendLog, sendRespLog = s.newChannelLog(tuiLogChannel)
+	default:
+		sendLog, sendRespLog = s.newWriterLog(os.Stderr)
 	}
 
 	// Start workers
-	q.startWorkers(&workersWG, jobsCh, q.hostClients, &counter, sendMessage)
+	s.startWorkers(&workersWG, jobsCh, &counter, sendLog, sendRespLog)
 
-	if !q.quiet {
+	if runTUI {
-		// Start streaming to terminal
+		go s.streamProgress(streamCtx, stopCtrl, streamCh, totalRequests, &counter, tuiLogChannel, showProgressBar)
-		//nolint:contextcheck // streamCtx must remain active until all workers complete to ensure all collected data is streamed
-		go q.streamProgress(streamCtx, stopCtrl, streamCh, totalRequests, &counter, messageChannel)
 	}
 
 	// Setup duration-based cancellation
-	q.setupDurationTimeout(ctx, jobsCancel)
+	s.setupDurationTimeout()
 	// Distribute jobs to workers.
 	// This blocks until all jobs are sent or the context is canceled.
-	q.sendJobs(jobsCtx, jobsCh)
+	s.sendJobs(jobsCh)
 
 	// Close the jobs channel so workers stop after completing their current job
 	close(jobsCh)
 	// Wait until all workers stopped
 	workersWG.Wait()
-	if messageChannel != nil {
+	if tuiLogChannel != nil {
-		close(messageChannel)
+		close(tuiLogChannel)
 	}
 
-	if !q.quiet {
+	if runTUI {
 		// Stop the progress streaming
 		streamCancel()
 		// Wait until progress streaming has completely stopped
@@ -202,65 +415,78 @@ func (q sarin) Start(ctx context.Context, stopCtrl *StopController) {
 	}
 }
 
-// newHostClients initializes HTTP clients for the given configuration.
+// newWriterLog builds the loggers that write formatted lines to w (a log file or
-// It can return the following errors:
+// stderr). sendLog stays general (it filters by each log's level), while sendRespLog
-// - types.ProxyDialError
+// only ever emits info, so its decision is baked once into a no-op when off.
-func newHostClients(
+func (s sarin) newWriterLog(w io.Writer) (runtimeLogger, respLogger) {
-	ctx context.Context,
+	// log.Logger serializes writes with its own mutex, so concurrent workers
-	timeout time.Duration,
+	// won't interleave lines.
-	proxies types.Proxies,
+	logger := log.New(w, "", 0)
-	workers uint,
+
-	requestURL *url.URL,
+	sendLog := gateSendLog(s.logInfo, s.logError, func(level runtimeLogLevel, text string) {
-	skipCertVerify bool,
+		logger.Println(formatRuntimeLogLine(time.Now(), level, text))
-) ([]*fasthttp.HostClient, error) {
+	})
-	proxiesRaw := make([]url.URL, len(proxies))
+
-	for i, proxy := range proxies {
+	var sendRespLog respLogger = noopRespLog
-		proxiesRaw[i] = url.URL(proxy)
+	if s.logInfo {
+		sendRespLog = func(duration time.Duration, resp *fasthttp.Response) {
+			logger.Println(formatRuntimeLogLine(time.Now(), runtimeLogLevelInfo, respToLogJSON(duration, resp)))
+		}
 	}
 
-	return NewHostClients(
+	return sendLog, sendRespLog
-		ctx,
-		timeout,
-		proxiesRaw,
-		workers,
-		requestURL,
-		skipCertVerify,
-	)
 }
 
-func (q sarin) startWorkers(wg *sync.WaitGroup, jobs <-chan struct{}, hostClients []*fasthttp.HostClient, counter *atomic.Uint64, sendMessage messageSender) {
+// newChannelLog builds the loggers that feed the TUI log box through ch, with the
-	for range max(q.workers, 1) {
+// same gating as newWriterLog.
+func (s sarin) newChannelLog(ch chan<- runtimeLog) (runtimeLogger, respLogger) {
+	sendLog := gateSendLog(s.logInfo, s.logError, func(level runtimeLogLevel, text string) {
+		ch <- runtimeLog{timestamp: time.Now(), level: level, text: text}
+	})
+
+	var sendRespLog respLogger = noopRespLog
+	if s.logInfo {
+		sendRespLog = func(duration time.Duration, resp *fasthttp.Response) {
+			ch <- runtimeLog{timestamp: time.Now(), level: runtimeLogLevelInfo, text: respToLog(duration, resp)}
+		}
+	}
+
+	return sendLog, sendRespLog
+}
+
+func (s sarin) startWorkers(wg *sync.WaitGroup, jobs <-chan struct{}, counter *atomic.Uint64, sendLog runtimeLogger, sendRespLog respLogger) {
+	for range max(s.workers, 1) {
 		wg.Go(func() {
-			q.Worker(jobs, NewHostClientGenerator(hostClients...), counter, sendMessage)
+			s.Worker(jobs, counter, sendLog, sendRespLog)
 		})
 	}
 }
 
-func (q sarin) setupDurationTimeout(ctx context.Context, cancel context.CancelFunc) {
+func (s sarin) setupDurationTimeout() {
-	if q.totalDuration != nil {
+	if s.totalDuration != nil {
 		go func() {
-			timer := time.NewTimer(*q.totalDuration)
+			timer := time.NewTimer(*s.totalDuration)
 			defer timer.Stop()
 			select {
 			case <-timer.C:
-				cancel()
+				s.jobsCancel()
-			case <-ctx.Done():
+			case <-s.jobsCtx.Done():
 				// Context cancelled, cleanup
 			}
 		}()
 	}
 }
 
-func (q sarin) sendJobs(ctx context.Context, jobs chan<- struct{}) {
+func (s sarin) sendJobs(jobs chan<- struct{}) {
-	if q.totalRequests != nil && *q.totalRequests > 0 {
+	if s.totalRequests != nil && *s.totalRequests > 0 {
-		for range *q.totalRequests {
+		for range *s.totalRequests {
-			if ctx.Err() != nil {
+			if s.jobsCtx.Err() != nil {
 				break
 			}
 			jobs <- struct{}{}
 		}
 	} else {
-		for ctx.Err() == nil {
+		for s.jobsCtx.Err() == nil {
 			jobs <- struct{}{}
 		}
 	}

internal/sarin/scripthttp.go

@@ -0,0 +1,176 @@
+package sarin
+
+import (
+	"context"
+	"crypto/tls"
+	"errors"
+	"net"
+	"net/url"
+	"time"
+
+	"github.com/valyala/fasthttp"
+	"go.aykhans.me/sarin/internal/script"
+	"go.aykhans.me/sarin/internal/types"
+)
+
+// scriptHTTPDefaultTimeout is the default timeout for script requests, independent of -T.
+const scriptHTTPDefaultTimeout = 30 * time.Second
+
+// scriptHTTPClient sends scripts' http.* requests. It is safe for concurrent use.
+type scriptHTTPClient struct {
+	ctx            context.Context //nolint:containedctx
+	client         *fasthttp.Client
+	insecureClient *fasthttp.Client
+	defaultTimeout time.Duration
+}
+
+var _ script.HTTPDoer = (*scriptHTTPClient)(nil)
+
+// newScriptHTTPClients creates one client per proxy, in the same order as NewHostClients.
+// It can return the following errors:
+//   - types.ProxyDialError
+func newScriptHTTPClients(ctx context.Context, proxies []url.URL, maxConns uint, maxResponseBody uint64) ([]*scriptHTTPClient, error) {
+	if len(proxies) == 0 {
+		return []*scriptHTTPClient{newScriptHTTPClient(ctx, fasthttp.DialDualStackTimeout, scriptHTTPDefaultTimeout, maxConns, maxResponseBody)}, nil
+	}
+
+	clients := make([]*scriptHTTPClient, 0, len(proxies))
+	for _, proxy := range proxies {
+		dial, err := NewProxyDialFuncWithTimeout(ctx, &proxy)
+		if err != nil {
+			return nil, types.NewProxyDialError(proxy.String(), err)
+		}
+		clients = append(clients, newScriptHTTPClient(ctx, dial, scriptHTTPDefaultTimeout, maxConns, maxResponseBody))
+	}
+	return clients, nil
+}
+
+func newScriptHTTPClient(
+	ctx context.Context,
+	dial fasthttp.DialFuncWithTimeout,
+	defaultTimeout time.Duration,
+	maxConns uint,
+	maxResponseBody uint64,
+) *scriptHTTPClient {
+	newClient := func(insecure bool) *fasthttp.Client {
+		// Read and write timeouts stay unset because they would cap the per-call timeout,
+		// so dialWithDeadline is what bounds the TLS handshake.
+		return &fasthttp.Client{
+			DialTimeout:               dialWithDeadline(dial),
+			MaxConnsPerHost:           safeUintToInt(maxConns),
+			MaxResponseBodySize:       safeUint64ToInt(maxResponseBody),
+			MaxIdemponentCallAttempts: 1,
+			ReadBufferSize:            64 << 10, // 64 KiB
+			TLSConfig: &tls.Config{
+				InsecureSkipVerify: insecure, //nolint:gosec
+			},
+			DisableHeaderNamesNormalizing: true,
+			DisablePathNormalizing:        true,
+			NoDefaultUserAgentHeader:      true,
+		}
+	}
+
+	return &scriptHTTPClient{
+		ctx:            ctx,
+		client:         newClient(false),
+		insecureClient: newClient(true),
+		defaultTimeout: defaultTimeout,
+	}
+}
+
+// dialWithDeadline dials within the request timeout and keeps it as the connection deadline,
+// so the TLS handshake fasthttp runs on the first write cannot outlive the request.
+func dialWithDeadline(dial fasthttp.DialFuncWithTimeout) fasthttp.DialFuncWithTimeout {
+	return func(addr string, timeout time.Duration) (net.Conn, error) {
+		if timeout <= 0 {
+			timeout = scriptHTTPDefaultTimeout
+		}
+		deadline := time.Now().Add(timeout)
+
+		conn, err := dial(addr, timeout)
+		if err != nil {
+			return nil, err
+		}
+		if err := conn.SetDeadline(deadline); err != nil {
+			conn.Close() //nolint:errcheck,gosec
+			return nil, err
+		}
+		return conn, nil
+	}
+}
+
+// Do sends the request. With maxRedirects the timeout applies to each hop.
+// It can return the following errors:
+//   - types.ScriptHTTPRequestError
+func (c *scriptHTTPClient) Do(r *script.HTTPRequest) (*script.HTTPResponse, error) {
+	if err := c.ctx.Err(); err != nil {
+		return nil, types.NewScriptHTTPRequestError(r.Method, r.URL, err)
+	}
+
+	parsedURL, err := url.Parse(r.URL)
+	if err != nil {
+		return nil, types.NewScriptHTTPRequestError(r.Method, r.URL, err)
+	}
+	if (parsedURL.Scheme != "http" && parsedURL.Scheme != "https") || parsedURL.Host == "" {
+		return nil, types.NewScriptHTTPRequestError(r.Method, r.URL, types.ErrScriptHTTPURLInvalid)
+	}
+
+	req := fasthttp.AcquireRequest()
+	resp := fasthttp.AcquireResponse()
+	defer fasthttp.ReleaseRequest(req)
+	defer fasthttp.ReleaseResponse(resp)
+
+	req.SetRequestURI(r.URL)
+	req.Header.SetMethod(r.Method)
+	for key, values := range r.Headers {
+		for _, value := range values {
+			req.Header.Add(key, value)
+		}
+	}
+
+	if len(r.Params) > 0 {
+		args := req.URI().QueryArgs()
+		for key, values := range r.Params {
+			for _, value := range values {
+				args.Add(key, value)
+			}
+		}
+	}
+
+	if len(r.Cookies) > 0 {
+		req.Header.Add("Cookie", cookieHeaderValue(r.Cookies))
+	}
+
+	req.SetBodyString(r.Body)
+
+	timeout := r.Timeout
+	if timeout <= 0 {
+		timeout = c.defaultTimeout
+	}
+
+	client := c.client
+	if r.Insecure {
+		client = c.insecureClient
+	}
+
+	req.SetTimeout(timeout)
+	if r.MaxRedirects > 0 {
+		err = client.DoRedirects(req, resp, r.MaxRedirects)
+	} else {
+		err = client.Do(req, resp)
+	}
+	if err != nil {
+		if errors.Is(err, fasthttp.ErrBodyTooLarge) {
+			err = types.ErrResponseBodyTooLarge
+		}
+		return nil, types.NewScriptHTTPRequestError(r.Method, r.URL, err)
+	}
+
+	body := resp.Body()
+
+	return &script.HTTPResponse{
+		Status:  resp.StatusCode(),
+		Headers: collectRespHeaders(resp),
+		Body:    string(body),
+	}, nil
+}

internal/sarin/stop.go

@@ -6,7 +6,7 @@ import (
 	"sync"
 	"sync/atomic"
 
-	tea "github.com/charmbracelet/bubbletea"
+	tea "charm.land/bubbletea/v2"
 )
 
 const forceExitCode = 130

internal/sarin/template.go

@@ -97,7 +97,7 @@ func NewDefaultTemplateFuncMap(randSource rand.Source, fileCache *FileCache) tem
 			return string(data), nil
 		},
 		// json_Object builds a JSON object from interleaved key-value pairs and returns it
-		// as a JSON string. Keys must be strings; values may be any JSON-encodable type.
+		// as a JSON string. Keys must be strings, values may be any JSON-encodable type.
 		// Usage: {{ json_Object "name" "Alice" "age" 30 }}
 		"json_Object": func(pairs ...any) (string, error) {
 			if len(pairs)%2 != 0 {
@@ -207,18 +207,20 @@ func NewDefaultTemplateFuncMap(randSource rand.Source, fileCache *FileCache) tem
 
 		// Fakeit / Person
 		// "fakeit_Person": fakeit.Person() *PersonInfo,
-		"fakeit_Name":       fakeit.Name,
+		"fakeit_Name":        fakeit.Name,
-		"fakeit_NamePrefix": fakeit.NamePrefix,
+		"fakeit_NamePrefix":  fakeit.NamePrefix,
-		"fakeit_NameSuffix": fakeit.NameSuffix,
+		"fakeit_NameSuffix":  fakeit.NameSuffix,
-		"fakeit_FirstName":  fakeit.FirstName,
+		"fakeit_FirstName":   fakeit.FirstName,
-		"fakeit_MiddleName": fakeit.MiddleName,
+		"fakeit_MiddleName":  fakeit.MiddleName,
-		"fakeit_LastName":   fakeit.LastName,
+		"fakeit_LastName":    fakeit.LastName,
-		"fakeit_Gender":     fakeit.Gender,
+		"fakeit_Gender":      fakeit.Gender,
-		"fakeit_Age":        fakeit.Age,
+		"fakeit_Age":         fakeit.Age,
-		"fakeit_Ethnicity":  fakeit.Ethnicity,
+		"fakeit_Ethnicity":   fakeit.Ethnicity,
-		"fakeit_SSN":        fakeit.SSN,
+		"fakeit_SSN":         fakeit.SSN,
-		"fakeit_EIN":        fakeit.EIN,
+		"fakeit_EIN":         fakeit.EIN,
-		"fakeit_Hobby":      fakeit.Hobby,
+		"fakeit_Hobby":       fakeit.Hobby,
+		"fakeit_SocialMedia": fakeit.SocialMedia,
+		"fakeit_Bio":         fakeit.Bio,
 		// "fakeit_Contact": fakeit.Contact() *ContactInfo,
 		"fakeit_Email":          fakeit.Email,
 		"fakeit_Phone":          fakeit.Phone,
@@ -232,6 +234,9 @@ func NewDefaultTemplateFuncMap(randSource rand.Source, fileCache *FileCache) tem
 		// "fakeit_Generate": fakeit.Generate(value string) string,
 		"fakeit_Regex": fakeit.Regex,
 
+		// Fakeit / Database
+		// "fakeit_SQL": fakeit.SQL(so *SQLOptions) (string, error),
+
 		// Fakeit / Auth
 		"fakeit_Username": fakeit.Username,
 		"fakeit_Password": fakeit.Password,
@@ -269,6 +274,15 @@ func NewDefaultTemplateFuncMap(randSource rand.Source, fileCache *FileCache) tem
 			return value
 		},
 
+		// Fakeit / Airline
+		"fakeit_AirlineAircraftType":  fakeit.AirlineAircraftType,
+		"fakeit_AirlineAirplane":      fakeit.AirlineAirplane,
+		"fakeit_AirlineAirport":       fakeit.AirlineAirport,
+		"fakeit_AirlineAirportIATA":   fakeit.AirlineAirportIATA,
+		"fakeit_AirlineFlightNumber":  fakeit.AirlineFlightNumber,
+		"fakeit_AirlineRecordLocator": fakeit.AirlineRecordLocator,
+		"fakeit_AirlineSeat":          fakeit.AirlineSeat,
+
 		// Fakeit / Game
 		"fakeit_Gamertag": fakeit.Gamertag,
 		// "fakeit_Dice": fakeit.Dice(numDice uint, sides []uint) []uint,
@@ -302,12 +316,16 @@ func NewDefaultTemplateFuncMap(randSource rand.Source, fileCache *FileCache) tem
 		"fakeit_NounCollectiveThing":  fakeit.NounCollectiveThing,
 		"fakeit_NounCountable":        fakeit.NounCountable,
 		"fakeit_NounUncountable":      fakeit.NounUncountable,
+		"fakeit_NounProper":           fakeit.NounProper,
+		"fakeit_NounDeterminer":       fakeit.NounDeterminer,
 
 		// Verbs
-		"fakeit_Verb":        fakeit.Verb,
+		"fakeit_Verb":             fakeit.Verb,
-		"fakeit_VerbAction":  fakeit.VerbAction,
+		"fakeit_VerbAction":       fakeit.VerbAction,
-		"fakeit_VerbLinking": fakeit.VerbLinking,
+		"fakeit_VerbLinking":      fakeit.VerbLinking,
-		"fakeit_VerbHelping": fakeit.VerbHelping,
+		"fakeit_VerbHelping":      fakeit.VerbHelping,
+		"fakeit_VerbTransitive":   fakeit.VerbTransitive,
+		"fakeit_VerbIntransitive": fakeit.VerbIntransitive,
 
 		// Adverbs
 		"fakeit_Adverb":                    fakeit.Adverb,
@@ -344,6 +362,7 @@ func NewDefaultTemplateFuncMap(randSource rand.Source, fileCache *FileCache) tem
 		"fakeit_PronounDemonstrative": fakeit.PronounDemonstrative,
 		"fakeit_PronounInterrogative": fakeit.PronounInterrogative,
 		"fakeit_PronounRelative":      fakeit.PronounRelative,
+		"fakeit_PronounIndefinite":    fakeit.PronounIndefinite,
 
 		// Connectives
 		"fakeit_Connective":            fakeit.Connective,
@@ -355,7 +374,8 @@ func NewDefaultTemplateFuncMap(randSource rand.Source, fileCache *FileCache) tem
 		"fakeit_ConnectiveExamplify":   fakeit.ConnectiveExamplify,
 
 		// Words
-		"fakeit_Word": fakeit.Word,
+		"fakeit_Word":         fakeit.Word,
+		"fakeit_Interjection": fakeit.Interjection,
 
 		// Text
 		"fakeit_Sentence":            fakeit.Sentence,
@@ -366,6 +386,11 @@ func NewDefaultTemplateFuncMap(randSource rand.Source, fileCache *FileCache) tem
 		"fakeit_Question":            fakeit.Question,
 		"fakeit_Quote":               fakeit.Quote,
 		"fakeit_Phrase":              fakeit.Phrase,
+		"fakeit_PhraseNoun":          fakeit.PhraseNoun,
+		"fakeit_PhraseVerb":          fakeit.PhraseVerb,
+		"fakeit_PhraseAdverb":        fakeit.PhraseAdverb,
+		"fakeit_PhrasePreposition":   fakeit.PhrasePreposition,
+		"fakeit_Comment":             fakeit.Comment,
 
 		// Fakeit / Foods
 		"fakeit_Fruit":     fakeit.Fruit,
@@ -375,6 +400,7 @@ func NewDefaultTemplateFuncMap(randSource rand.Source, fileCache *FileCache) tem
 		"fakeit_Dinner":    fakeit.Dinner,
 		"fakeit_Snack":     fakeit.Snack,
 		"fakeit_Dessert":   fakeit.Dessert,
+		"fakeit_Drink":     fakeit.Drink,
 
 		// Fakeit / Misc
 		"fakeit_Bool": fakeit.Bool,
@@ -387,6 +413,7 @@ func NewDefaultTemplateFuncMap(randSource rand.Source, fileCache *FileCache) tem
 		"fakeit_Color":      fakeit.Color,
 		"fakeit_HexColor":   fakeit.HexColor,
 		"fakeit_RGBColor":   fakeit.RGBColor,
+		"fakeit_HSLColor":   fakeit.HSLColor,
 		"fakeit_SafeColor":  fakeit.SafeColor,
 		"fakeit_NiceColors": fakeit.NiceColors,
 
@@ -530,6 +557,7 @@ func NewDefaultTemplateFuncMap(randSource rand.Source, fileCache *FileCache) tem
 		// Fakeit / Language
 		"fakeit_Language":             fakeit.Language,
 		"fakeit_LanguageAbbreviation": fakeit.LanguageAbbreviation,
+		"fakeit_LanguageBCP":          fakeit.LanguageBCP,
 		"fakeit_ProgrammingLanguage":  fakeit.ProgrammingLanguage,
 
 		// Fakeit / Number
@@ -540,25 +568,29 @@ func NewDefaultTemplateFuncMap(randSource rand.Source, fileCache *FileCache) tem
 		"fakeit_Int16":        fakeit.Int16,
 		"fakeit_Int32":        fakeit.Int32,
 		"fakeit_Int64":        fakeit.Int64,
+		"fakeit_IntRange":     fakeit.IntRange,
 		"fakeit_Uint":         fakeit.Uint,
 		"fakeit_UintN":        fakeit.UintN,
 		"fakeit_Uint8":        fakeit.Uint8,
 		"fakeit_Uint16":       fakeit.Uint16,
 		"fakeit_Uint32":       fakeit.Uint32,
 		"fakeit_Uint64":       fakeit.Uint64,
+		"fakeit_UintRange":    fakeit.UintRange,
 		"fakeit_Float32":      fakeit.Float32,
 		"fakeit_Float32Range": fakeit.Float32Range,
 		"fakeit_Float64":      fakeit.Float64,
 		"fakeit_Float64Range": fakeit.Float64Range,
 		// "fakeit_ShuffleInts":  fakeit.ShuffleInts,
-		"fakeit_RandomInt": fakeit.RandomInt,
+		"fakeit_RandomInt":  fakeit.RandomInt,
-		"fakeit_HexUint":   fakeit.HexUint,
+		"fakeit_RandomUint": fakeit.RandomUint,
+		"fakeit_HexUint":    fakeit.HexUint,
 
 		// Fakeit / String
 		"fakeit_Digit":    fakeit.Digit,
 		"fakeit_DigitN":   fakeit.DigitN,
 		"fakeit_Letter":   fakeit.Letter,
 		"fakeit_LetterN":  fakeit.LetterN,
+		"fakeit_Vowel":    fakeit.Vowel,
 		"fakeit_Lexify":   fakeit.Lexify,
 		"fakeit_Numerify": fakeit.Numerify,
 		// "fakeit_ShuffleStrings": fakeit.ShuffleStrings,
@@ -602,12 +634,14 @@ func NewDefaultTemplateFuncMap(randSource rand.Source, fileCache *FileCache) tem
 
 		// Fakeit / Error
 		"fakeit_Error":           func() string { return fakeit.Error().Error() },
+		"fakeit_ErrorObject":     func() string { return fakeit.ErrorObject().Error() },
 		"fakeit_ErrorDatabase":   func() string { return fakeit.ErrorDatabase().Error() },
 		"fakeit_ErrorGRPC":       func() string { return fakeit.ErrorGRPC().Error() },
 		"fakeit_ErrorHTTP":       func() string { return fakeit.ErrorHTTP().Error() },
 		"fakeit_ErrorHTTPClient": func() string { return fakeit.ErrorHTTPClient().Error() },
 		"fakeit_ErrorHTTPServer": func() string { return fakeit.ErrorHTTPServer().Error() },
 		"fakeit_ErrorRuntime":    func() string { return fakeit.ErrorRuntime().Error() },
+		"fakeit_ErrorValidation": func() string { return fakeit.ErrorValidation().Error() },
 
 		// Fakeit / School
 		"fakeit_School": fakeit.School,
@@ -717,7 +751,7 @@ func NewDefaultBodyTemplateFuncMap(
 
 				switch {
 				case strings.HasPrefix(val, "@@"):
-					// Escaped @ - send as literal string without first @
+					// Escaped @: send the string without the first @
 					if err := writer.WriteField(key, val[1:]); err != nil {
 						return "", err
 					}

internal/sarin/tui.go

@@ -2,38 +2,86 @@ package sarin
 
 import (
 	"context"
+	"slices"
 	"strconv"
 	"strings"
 	"sync/atomic"
 	"time"
 
-	"github.com/charmbracelet/bubbles/progress"
+	"charm.land/bubbles/v2/progress"
-	"github.com/charmbracelet/bubbles/spinner"
+	"charm.land/bubbles/v2/spinner"
-	tea "github.com/charmbracelet/bubbletea"
+	tea "charm.land/bubbletea/v2"
-	"github.com/charmbracelet/lipgloss"
+	"charm.land/lipgloss/v2"
 )
 
 type tickMsg time.Time
 
-var (
+// logBatch carries the log lines accumulated since the last repaint.
-	helpStyle           = lipgloss.NewStyle().Foreground(lipgloss.Color("#d1d1d1"))
+type logBatch []runtimeLog
-	errorStyle          = lipgloss.NewStyle().Foreground(lipgloss.Color("#FC5B5B")).Bold(true)
+
-	warningStyle        = lipgloss.NewStyle().Foreground(lipgloss.Color("#FFD93D")).Bold(true)
+const (
-	messageChannelStyle = lipgloss.NewStyle().
+	// logBoxLines is how many lines the log box shows at once.
-				Border(lipgloss.ThickBorder(), false, false, false, true).
+	logBoxLines = 8
-				BorderForeground(lipgloss.Color("#757575")).
+	// logBatchInterval is how often accumulated logs are handed to the program.
-				PaddingLeft(1).
+	logBatchInterval = 250 * time.Millisecond
-				Margin(1, 0, 0, 0).
-				Foreground(lipgloss.Color("#888888"))
 )
 
+var (
+	helpStyle  = lipgloss.NewStyle().Foreground(lipgloss.Color("#d1d1d1"))
+	errorStyle = lipgloss.NewStyle().Foreground(lipgloss.Color("#FC5B5B")).Bold(true)
+	infoStyle  = lipgloss.NewStyle().Foreground(lipgloss.Color("#5BC0FC")).Bold(true)
+
+	errorLabel = errorStyle.Render("ERROR: ")
+	infoLabel  = infoStyle.Render("INFO: ")
+
+	logChannelStyle = lipgloss.NewStyle().
+			Border(lipgloss.ThickBorder(), false, false, false, true).
+			BorderForeground(lipgloss.Color("#757575")).
+			PaddingLeft(1).
+			Margin(1, 0, 0, 0).
+			Foreground(lipgloss.Color("#888888"))
+)
+
+// renderRuntimeLog builds a single styled log line for the TUI log box.
+func renderRuntimeLog(log runtimeLog) string {
+	label := errorLabel
+	if log.level == runtimeLogLevelInfo {
+		label = infoLabel
+	}
+	return "[" + log.timestamp.Format("15:04:05") + "] " + label + log.text
+}
+
+// renderLogBox renders the styled log box, or "" when there are no lines.
+func renderLogBox(logs []string) string {
+	var b strings.Builder
+	for i, line := range logs {
+		if len(line) > 0 {
+			b.WriteString(line)
+			if i < len(logs)-1 {
+				b.WriteString("\n")
+			}
+		}
+	}
+	if b.Len() == 0 {
+		return ""
+	}
+	return logChannelStyle.Render(b.String())
+}
+
+func helpLine(cancelling bool) string {
+	if cancelling {
+		return helpStyle.Render("Stopping... (Ctrl+C again to force)")
+	}
+	return helpStyle.Render("Press Ctrl+C to quit")
+}
+
 type progressModel struct {
 	progress   progress.Model
 	startTime  time.Time
-	messages   []string
+	logs       []string
 	counter    *atomic.Uint64
-	current    uint64
 	maxValue   uint64
+	showBar    bool
 	ctx        context.Context //nolint:containedctx
 	stop       func()
 	cancelling bool
@@ -45,33 +93,24 @@ func (m progressModel) Init() tea.Cmd {
 
 func (m progressModel) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 	switch msg := msg.(type) {
-	case tea.KeyMsg:
+	case tea.KeyPressMsg:
-		if msg.Type == tea.KeyCtrlC {
+		if msg.String() == "ctrl+c" {
 			m.cancelling = true
 			m.stop()
 		}
 		return m, nil
 
 	case tea.WindowSizeMsg:
-		m.progress.Width = max(10, msg.Width-1)
+		m.progress.SetWidth(max(10, msg.Width-1))
 		if m.ctx.Err() != nil {
 			return m, tea.Quit
 		}
 		return m, nil
 
-	case runtimeMessage:
+	case logBatch:
-		var msgBuilder strings.Builder
+		for _, entry := range msg {
-		msgBuilder.WriteString("[")
+			m.logs = append(m.logs[1:], renderRuntimeLog(entry))
-		msgBuilder.WriteString(msg.timestamp.Format("15:04:05"))
-		msgBuilder.WriteString("] ")
-		switch msg.level {
-		case runtimeMessageLevelError:
-			msgBuilder.WriteString(errorStyle.Render("ERROR: "))
-		case runtimeMessageLevelWarning:
-			msgBuilder.WriteString(warningStyle.Render("WARNING: "))
 		}
-		msgBuilder.WriteString(msg.text)
-		m.messages = append(m.messages[1:], msgBuilder.String())
 		if m.ctx.Err() != nil {
 			return m, tea.Quit
 		}
@@ -91,39 +130,28 @@ func (m progressModel) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 	}
 }
 
-func (m progressModel) View() string {
+func (m progressModel) View() tea.View {
-	var messagesBuilder strings.Builder
+	var b strings.Builder
-	for i, msg := range m.messages {
+	if box := renderLogBox(m.logs); box != "" {
-		if len(msg) > 0 {
+		b.WriteString(box)
-			messagesBuilder.WriteString(msg)
+		b.WriteString("\n")
-			if i < len(m.messages)-1 {
-				messagesBuilder.WriteString("\n")
-			}
-		}
 	}
 
-	var finalBuilder strings.Builder
+	if m.showBar {
-	if messagesBuilder.Len() > 0 {
+		current := m.counter.Load()
-		finalBuilder.WriteString(messageChannelStyle.Render(messagesBuilder.String()))
+		b.WriteString("\n ")
-		finalBuilder.WriteString("\n")
+		b.WriteString(strconv.FormatUint(current, 10))
+		b.WriteString("/")
+		b.WriteString(strconv.FormatUint(m.maxValue, 10))
+		b.WriteString(" - ")
+		b.WriteString(time.Since(m.startTime).Round(time.Second / 10).String())
+		b.WriteString("\n ")
+		b.WriteString(m.progress.ViewAs(float64(current) / float64(m.maxValue)))
 	}
 
-	m.current = m.counter.Load()
+	b.WriteString("\n\n  ")
-	finalBuilder.WriteString("\n ")
+	b.WriteString(helpLine(m.cancelling))
-	finalBuilder.WriteString(strconv.FormatUint(m.current, 10))
+	return tea.NewView(b.String())
-	finalBuilder.WriteString("/")
-	finalBuilder.WriteString(strconv.FormatUint(m.maxValue, 10))
-	finalBuilder.WriteString(" - ")
-	finalBuilder.WriteString(time.Since(m.startTime).Round(time.Second / 10).String())
-	finalBuilder.WriteString("\n ")
-	finalBuilder.WriteString(m.progress.ViewAs(float64(m.current) / float64(m.maxValue)))
-	finalBuilder.WriteString("\n\n  ")
-	if m.cancelling {
-		finalBuilder.WriteString(helpStyle.Render("Stopping... (Ctrl+C again to force)"))
-	} else {
-		finalBuilder.WriteString(helpStyle.Render("Press Ctrl+C to quit"))
-	}
-	return finalBuilder.String()
 }
 
 func progressTickCmd() tea.Cmd {
@@ -138,7 +166,8 @@ type infiniteProgressModel struct {
 	spinner    spinner.Model
 	startTime  time.Time
 	counter    *atomic.Uint64
-	messages   []string
+	logs       []string
+	showBar    bool
 	ctx        context.Context //nolint:containedctx
 	quit       bool
 	stop       func()
@@ -151,26 +180,17 @@ func (m infiniteProgressModel) Init() tea.Cmd {
 
 func (m infiniteProgressModel) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 	switch msg := msg.(type) {
-	case tea.KeyMsg:
+	case tea.KeyPressMsg:
-		if msg.Type == tea.KeyCtrlC {
+		if msg.String() == "ctrl+c" {
 			m.cancelling = true
 			m.stop()
 		}
 		return m, nil
 
-	case runtimeMessage:
+	case logBatch:
-		var msgBuilder strings.Builder
+		for _, entry := range msg {
-		msgBuilder.WriteString("[")
+			m.logs = append(m.logs[1:], renderRuntimeLog(entry))
-		msgBuilder.WriteString(msg.timestamp.Format("15:04:05"))
-		msgBuilder.WriteString("] ")
-		switch msg.level {
-		case runtimeMessageLevelError:
-			msgBuilder.WriteString(errorStyle.Render("ERROR: "))
-		case runtimeMessageLevelWarning:
-			msgBuilder.WriteString(warningStyle.Render("WARNING: "))
 		}
-		msgBuilder.WriteString(msg.text)
-		m.messages = append(m.messages[1:], msgBuilder.String())
 		if m.ctx.Err() != nil {
 			m.quit = true
 			return m, tea.Quit
@@ -188,65 +208,64 @@ func (m infiniteProgressModel) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 	}
 }
 
-func (m infiniteProgressModel) View() string {
+func (m infiniteProgressModel) View() tea.View {
-	var messagesBuilder strings.Builder
+	var b strings.Builder
-	for i, msg := range m.messages {
+	if box := renderLogBox(m.logs); box != "" {
-		if len(msg) > 0 {
+		b.WriteString(box)
-			messagesBuilder.WriteString(msg)
+		b.WriteString("\n")
-			if i < len(m.messages)-1 {
-				messagesBuilder.WriteString("\n")
-			}
-		}
 	}
 
-	var finalBuilder strings.Builder
+	// Without a spinner, the view is just the log box (plus help until quit).
-	if messagesBuilder.Len() > 0 {
+	if !m.showBar {
-		finalBuilder.WriteString(messageChannelStyle.Render(messagesBuilder.String()))
+		if !m.quit {
-		finalBuilder.WriteString("\n")
+			b.WriteString("\n\n  ")
+			b.WriteString(helpLine(m.cancelling))
+		}
+		return tea.NewView(b.String())
 	}
 
 	if m.quit {
-		finalBuilder.WriteString("\n  ")
+		b.WriteString("\n  ")
-		finalBuilder.WriteString(strconv.FormatUint(m.counter.Load(), 10))
+		b.WriteString(strconv.FormatUint(m.counter.Load(), 10))
-		finalBuilder.WriteString("  ")
+		b.WriteString("  ")
-		finalBuilder.WriteString(infiniteProgressStyle.Render("∙∙∙∙∙"))
+		b.WriteString(infiniteProgressStyle.Render("∙∙∙∙∙"))
-		finalBuilder.WriteString("  ")
+		b.WriteString("  ")
-		finalBuilder.WriteString(time.Since(m.startTime).Round(time.Second / 10).String())
+		b.WriteString(time.Since(m.startTime).Round(time.Second / 10).String())
-		finalBuilder.WriteString("\n\n")
+		b.WriteString("\n\n")
 	} else {
-		finalBuilder.WriteString("\n  ")
+		b.WriteString("\n  ")
-		finalBuilder.WriteString(strconv.FormatUint(m.counter.Load(), 10))
+		b.WriteString(strconv.FormatUint(m.counter.Load(), 10))
-		finalBuilder.WriteString("  ")
+		b.WriteString("  ")
-		finalBuilder.WriteString(m.spinner.View())
+		b.WriteString(m.spinner.View())
-		finalBuilder.WriteString("  ")
+		b.WriteString("  ")
-		finalBuilder.WriteString(time.Since(m.startTime).Round(time.Second / 10).String())
+		b.WriteString(time.Since(m.startTime).Round(time.Second / 10).String())
-		finalBuilder.WriteString("\n\n  ")
+		b.WriteString("\n\n  ")
-		if m.cancelling {
+		b.WriteString(helpLine(m.cancelling))
-			finalBuilder.WriteString(helpStyle.Render("Stopping... (Ctrl+C again to force)"))
-		} else {
-			finalBuilder.WriteString(helpStyle.Render("Press Ctrl+C to quit"))
-		}
 	}
-	return finalBuilder.String()
+	return tea.NewView(b.String())
 }
 
-func (q sarin) streamProgress(
+func (s sarin) streamProgress(
 	ctx context.Context,
 	stopCtrl *StopController,
 	done chan<- struct{},
 	total uint64,
 	counter *atomic.Uint64,
-	messageChannel <-chan runtimeMessage,
+	logChannel <-chan runtimeLog,
+	showBar bool,
 ) {
 	var program *tea.Program
 	if total > 0 {
 		model := progressModel{
-			progress:  progress.New(progress.WithGradient("#151594", "#00D4FF")),
+			progress: progress.New(
+				progress.WithColors(lipgloss.Color("#151594"), lipgloss.Color("#00D4FF")),
+				progress.WithFillCharacters(progress.DefaultFullCharFullBlock, progress.DefaultEmptyCharBlock),
+			),
 			startTime: time.Now(),
-			messages:  make([]string, 8),
+			logs:      make([]string, logBoxLines),
 			counter:   counter,
-			current:   0,
 			maxValue:  total,
+			showBar:   showBar,
 			ctx:       ctx,
 			stop:      stopCtrl.Stop,
 		}
@@ -274,7 +293,8 @@ func (q sarin) streamProgress(
 			),
 			startTime: time.Now(),
 			counter:   counter,
-			messages:  make([]string, 8),
+			logs:      make([]string, logBoxLines),
+			showBar:   showBar,
 			ctx:       ctx,
 			stop:      stopCtrl.Stop,
 			quit:      false,
@@ -286,9 +306,35 @@ func (q sarin) streamProgress(
 	stopCtrl.AttachProgram(program)
 	defer stopCtrl.AttachProgram(nil)
 
+	// Bubble Tea repaints once per message, so forwarding every log made the run
+	// wait on the terminal. Send only what the box shows, on a fixed cadence.
 	go func() {
-		for msg := range messageChannel {
+		ticker := time.NewTicker(logBatchInterval)
-			program.Send(msg)
+		defer ticker.Stop()
+
+		pending := make(logBatch, 0, logBoxLines)
+		flush := func() {
+			if len(pending) == 0 {
+				return
+			}
+			program.Send(slices.Clone(pending))
+			pending = pending[:0]
+		}
+
+		for {
+			select {
+			case entry, ok := <-logChannel:
+				if !ok {
+					flush()
+					return
+				}
+				if len(pending) == logBoxLines {
+					pending = append(pending[:0], pending[1:]...)
+				}
+				pending = append(pending, entry)
+			case <-ticker.C:
+				flush()
+			}
 		}
 	}()
 

internal/sarin/worker.go

@@ -1,39 +1,71 @@
 package sarin
 
 import (
+	"errors"
+	"net"
 	"strconv"
+	"strings"
 	"sync/atomic"
 	"time"
 
 	"github.com/valyala/fasthttp"
 	"go.aykhans.me/sarin/internal/script"
+	"go.aykhans.me/sarin/internal/types"
 )
 
 const dryRunResponseKey = "dry-run"
 
 // statusCodeStrings contains pre-computed string representations for HTTP status codes 100-599.
-var statusCodeStrings = func() map[int]string {
+var statusCodeStrings = func() [500]string {
-	m := make(map[int]string, 500)
+	var codes [500]string
-	for i := 100; i < 600; i++ {
+	for i := range codes {
-		m[i] = strconv.Itoa(i)
+		codes[i] = strconv.Itoa(i + 100)
 	}
-	return m
+	return codes
 }()
 
 // statusCodeToString returns a string representation of the HTTP status code.
-// Uses a pre-computed map for codes 100-599, falls back to strconv.Itoa for others.
+// Uses a pre-computed table for codes 100-599, falls back to strconv.Itoa for others.
 func statusCodeToString(code int) string {
-	if s, ok := statusCodeStrings[code]; ok {
+	if i := code - 100; i >= 0 && i < len(statusCodeStrings) {
-		return s
+		return statusCodeStrings[i]
 	}
 	return strconv.Itoa(code)
 }
 
-func (q sarin) Worker(
+// responseErrorKey drops the local address, whose port would mint a stats entry per connection.
+func responseErrorKey(err error) string {
+	if errors.Is(err, fasthttp.ErrBodyTooLarge) {
+		return types.ErrResponseBodyTooLarge.Error()
+	}
+
+	message := err.Error()
+
+	var opErr *net.OpError
+	if !errors.As(err, &opErr) || opErr.Source == nil {
+		return message
+	}
+
+	withoutSource := *opErr
+	withoutSource.Source = nil
+	return strings.Replace(message, opErr.Error(), withoutSource.Error(), 1)
+}
+
+// requestErrorKey keys a generation failure by its source instead of its message.
+// A script picks its own URLs and error texts, so the message would mint a new
+// stats entry per request. The full message still goes to the runtime log.
+func requestErrorKey(err error) string {
+	if chainErr, ok := errors.AsType[types.ScriptChainError](err); ok {
+		return chainErr.EngineType + " script[" + strconv.Itoa(chainErr.Index) + "] error"
+	}
+	return "request generation error"
+}
+
+func (s sarin) Worker(
 	jobs <-chan struct{},
-	hostClientGenerator HostClientGenerator,
 	counter *atomic.Uint64,
-	sendMessage messageSender,
+	sendLog runtimeLogger,
+	sendRespLog respLogger,
 ) {
 	req := fasthttp.AcquireRequest()
 	resp := fasthttp.AcquireResponse()
@@ -43,143 +75,174 @@ func (q sarin) Worker(
 	// Create script transformer for this worker (engines are not thread-safe)
 	// Scripts are pre-validated in NewSarin, so this should not fail
 	var scriptTransformer *script.Transformer
-	if !q.scriptChain.IsEmpty() {
+	if !s.scriptChain.IsEmpty() {
 		var err error
-		scriptTransformer, err = q.scriptChain.NewTransformer()
+		scriptTransformer, err = s.scriptChain.NewTransformer()
 		if err != nil {
 			panic(err)
 		}
 		defer scriptTransformer.Close()
 	}
 
+	nextClientIndex := newClientIndexGenerator(len(s.hostClients))
+	bindScriptProxy := s.newScriptProxyBinder(scriptTransformer)
+
 	requestGenerator, isDynamic := NewRequestGenerator(
-		q.methods, q.requestURL, q.params, q.headers, q.cookies, q.bodies, q.values, q.fileCache, scriptTransformer,
+		s.methods, s.requestURL, s.params, s.headers, s.cookies, s.bodies, s.values, s.fileCache, scriptTransformer,
 	)
 
-	if q.dryRun {
+	if s.dryRun {
 		switch {
-		case q.collectStats && isDynamic:
+		case s.collectStats && isDynamic:
-			q.workerDryRunStatsWithDynamic(jobs, req, requestGenerator, counter, sendMessage)
+			s.workerDryRunStatsWithDynamic(jobs, req, requestGenerator, nextClientIndex, bindScriptProxy, counter, sendLog)
-		case q.collectStats && !isDynamic:
+		case s.collectStats && !isDynamic:
-			q.workerDryRunStatsWithStatic(jobs, req, requestGenerator, counter, sendMessage)
+			s.workerDryRunStatsWithStatic(jobs, req, requestGenerator, counter, sendLog)
-		case !q.collectStats && isDynamic:
+		case !s.collectStats && isDynamic:
-			q.workerDryRunNoStatsWithDynamic(jobs, req, requestGenerator, counter, sendMessage)
+			s.workerDryRunNoStatsWithDynamic(jobs, req, requestGenerator, nextClientIndex, bindScriptProxy, counter, sendLog)
 		default:
-			q.workerDryRunNoStatsWithStatic(jobs, req, requestGenerator, counter, sendMessage)
+			s.workerDryRunNoStatsWithStatic(jobs, req, requestGenerator, counter, sendLog)
 		}
 	} else {
 		switch {
-		case q.collectStats && isDynamic:
+		case s.collectStats && isDynamic:
-			q.workerStatsWithDynamic(jobs, req, resp, requestGenerator, hostClientGenerator, counter, sendMessage)
+			s.workerStatsWithDynamic(jobs, req, resp, requestGenerator, nextClientIndex, bindScriptProxy, counter, sendLog, sendRespLog)
-		case q.collectStats && !isDynamic:
+		case s.collectStats && !isDynamic:
-			q.workerStatsWithStatic(jobs, req, resp, requestGenerator, hostClientGenerator, counter, sendMessage)
+			s.workerStatsWithStatic(jobs, req, resp, requestGenerator, nextClientIndex, counter, sendLog, sendRespLog)
-		case !q.collectStats && isDynamic:
+		case !s.collectStats && isDynamic:
-			q.workerNoStatsWithDynamic(jobs, req, resp, requestGenerator, hostClientGenerator, counter, sendMessage)
+			s.workerNoStatsWithDynamic(jobs, req, resp, requestGenerator, nextClientIndex, bindScriptProxy, counter, sendLog, sendRespLog)
 		default:
-			q.workerNoStatsWithStatic(jobs, req, resp, requestGenerator, hostClientGenerator, counter, sendMessage)
+			s.workerNoStatsWithStatic(jobs, req, resp, requestGenerator, nextClientIndex, counter, sendLog, sendRespLog)
 		}
 	}
 }
 
-func (q sarin) workerStatsWithDynamic(
+// newScriptProxyBinder returns a func that sends the scripts' http.* calls through proxy i.
+func (s sarin) newScriptProxyBinder(scriptTransformer *script.Transformer) func(i int) {
+	if scriptTransformer == nil || scriptTransformer.IsEmpty() {
+		return func(int) {}
+	}
+	return func(i int) {
+		scriptTransformer.SetHTTPDoer(s.scriptHTTPClients[i])
+	}
+}
+
+func (s sarin) workerStatsWithDynamic(
 	jobs <-chan struct{},
 	req *fasthttp.Request,
 	resp *fasthttp.Response,
 	requestGenerator RequestGenerator,
-	hostClientGenerator HostClientGenerator,
+	nextClientIndex clientIndexGenerator,
+	bindScriptProxy func(int),
 	counter *atomic.Uint64,
-	sendMessage messageSender,
+	sendLog runtimeLogger,
+	sendRespLog respLogger,
 ) {
 	for range jobs {
 		req.Reset()
-		resp.Reset()
 
+		// Bound before generation so scripts' http.* calls use the main request's proxy.
+		clientIndex := nextClientIndex()
+		bindScriptProxy(clientIndex)
 		if err := requestGenerator(req); err != nil {
-			q.responses.Add(err.Error(), 0)
+			s.responses.Add(requestErrorKey(err), 0)
-			sendMessage(runtimeMessageLevelError, err.Error())
+			sendLog(runtimeLogLevelError, err.Error())
 			counter.Add(1)
 			continue
 		}
 
 		startTime := time.Now()
-		err := hostClientGenerator().DoTimeout(req, resp, q.timeout)
+		err := s.hostClients[clientIndex].DoTimeout(req, resp, s.timeout)
+		respDuration := time.Since(startTime)
+
 		if err != nil {
-			q.responses.Add(err.Error(), time.Since(startTime))
+			s.responses.Add(responseErrorKey(err), respDuration)
 		} else {
-			q.responses.Add(statusCodeToString(resp.StatusCode()), time.Since(startTime))
+			s.responses.Add(statusCodeToString(resp.StatusCode()), respDuration)
+			sendRespLog(respDuration, resp)
 		}
 		counter.Add(1)
 	}
 }
 
-func (q sarin) workerStatsWithStatic(
+func (s sarin) workerStatsWithStatic(
 	jobs <-chan struct{},
 	req *fasthttp.Request,
 	resp *fasthttp.Response,
 	requestGenerator RequestGenerator,
-	hostClientGenerator HostClientGenerator,
+	nextClientIndex clientIndexGenerator,
 	counter *atomic.Uint64,
-	sendMessage messageSender,
+	sendLog runtimeLogger,
+	sendRespLog respLogger,
 ) {
 	if err := requestGenerator(req); err != nil {
-		// Static request generation failed - record all jobs as errors
+		// Static request generation failed, so record all jobs as errors
+		errorKey := requestErrorKey(err)
 		for range jobs {
-			q.responses.Add(err.Error(), 0)
+			s.responses.Add(errorKey, 0)
-			sendMessage(runtimeMessageLevelError, err.Error())
+			sendLog(runtimeLogLevelError, err.Error())
 			counter.Add(1)
 		}
 		return
 	}
 
 	for range jobs {
-		resp.Reset()
-
 		startTime := time.Now()
-		err := hostClientGenerator().DoTimeout(req, resp, q.timeout)
+		err := s.hostClients[nextClientIndex()].DoTimeout(req, resp, s.timeout)
+		respDuration := time.Since(startTime)
 		if err != nil {
-			q.responses.Add(err.Error(), time.Since(startTime))
+			s.responses.Add(responseErrorKey(err), respDuration)
 		} else {
-			q.responses.Add(statusCodeToString(resp.StatusCode()), time.Since(startTime))
+			s.responses.Add(statusCodeToString(resp.StatusCode()), respDuration)
+			sendRespLog(respDuration, resp)
 		}
 		counter.Add(1)
 	}
 }
 
-func (q sarin) workerNoStatsWithDynamic(
+func (s sarin) workerNoStatsWithDynamic(
 	jobs <-chan struct{},
 	req *fasthttp.Request,
 	resp *fasthttp.Response,
 	requestGenerator RequestGenerator,
-	hostClientGenerator HostClientGenerator,
+	nextClientIndex clientIndexGenerator,
+	bindScriptProxy func(int),
 	counter *atomic.Uint64,
-	sendMessage messageSender,
+	sendLog runtimeLogger,
+	sendRespLog respLogger,
 ) {
 	for range jobs {
 		req.Reset()
-		resp.Reset()
+		// Bound before generation so scripts' http.* calls use the main request's proxy.
+		clientIndex := nextClientIndex()
+		bindScriptProxy(clientIndex)
 		if err := requestGenerator(req); err != nil {
-			sendMessage(runtimeMessageLevelError, err.Error())
+			sendLog(runtimeLogLevelError, err.Error())
 			counter.Add(1)
 			continue
 		}
-		_ = hostClientGenerator().DoTimeout(req, resp, q.timeout)
+		startTime := time.Now()
+		err := s.hostClients[clientIndex].DoTimeout(req, resp, s.timeout)
+		if err == nil {
+			sendRespLog(time.Since(startTime), resp)
+		}
 		counter.Add(1)
 	}
 }
 
-func (q sarin) workerNoStatsWithStatic(
+func (s sarin) workerNoStatsWithStatic(
 	jobs <-chan struct{},
 	req *fasthttp.Request,
 	resp *fasthttp.Response,
 	requestGenerator RequestGenerator,
-	hostClientGenerator HostClientGenerator,
+	nextClientIndex clientIndexGenerator,
 	counter *atomic.Uint64,
-	sendMessage messageSender,
+	sendLog runtimeLogger,
+	sendRespLog respLogger,
 ) {
 	if err := requestGenerator(req); err != nil {
-		sendMessage(runtimeMessageLevelError, err.Error())
+		sendLog(runtimeLogLevelError, err.Error())
 
-		// Static request generation failed - just count the jobs without sending
+		// Static request generation failed, so just count the jobs without sending
 		for range jobs {
 			counter.Add(1)
 		}
@@ -187,81 +250,93 @@ func (q sarin) workerNoStatsWithStatic(
 	}
 
 	for range jobs {
-		resp.Reset()
+		startTime := time.Now()
-		_ = hostClientGenerator().DoTimeout(req, resp, q.timeout)
+		err := s.hostClients[nextClientIndex()].DoTimeout(req, resp, s.timeout)
+		if err == nil {
+			sendRespLog(time.Since(startTime), resp)
+		}
 		counter.Add(1)
 	}
 }
 
-func (q sarin) workerDryRunStatsWithDynamic(
+func (s sarin) workerDryRunStatsWithDynamic(
 	jobs <-chan struct{},
 	req *fasthttp.Request,
 	requestGenerator RequestGenerator,
+	nextClientIndex clientIndexGenerator,
+	bindScriptProxy func(int),
 	counter *atomic.Uint64,
-	sendMessage messageSender,
+	sendLog runtimeLogger,
 ) {
 	for range jobs {
 		req.Reset()
+		// Nothing is sent, this only binds a proxy for the scripts' http.* calls.
+		bindScriptProxy(nextClientIndex())
 		startTime := time.Now()
 		if err := requestGenerator(req); err != nil {
-			q.responses.Add(err.Error(), time.Since(startTime))
+			s.responses.Add(requestErrorKey(err), time.Since(startTime))
-			sendMessage(runtimeMessageLevelError, err.Error())
+			sendLog(runtimeLogLevelError, err.Error())
 			counter.Add(1)
 			continue
 		}
-		q.responses.Add(dryRunResponseKey, time.Since(startTime))
+		s.responses.Add(dryRunResponseKey, time.Since(startTime))
 		counter.Add(1)
 	}
 }
 
-func (q sarin) workerDryRunStatsWithStatic(
+func (s sarin) workerDryRunStatsWithStatic(
 	jobs <-chan struct{},
 	req *fasthttp.Request,
 	requestGenerator RequestGenerator,
 	counter *atomic.Uint64,
-	sendMessage messageSender,
+	sendLog runtimeLogger,
 ) {
 	if err := requestGenerator(req); err != nil {
-		// Static request generation failed - record all jobs as errors
+		// Static request generation failed, so record all jobs as errors
+		errorKey := requestErrorKey(err)
 		for range jobs {
-			q.responses.Add(err.Error(), 0)
+			s.responses.Add(errorKey, 0)
-			sendMessage(runtimeMessageLevelError, err.Error())
+			sendLog(runtimeLogLevelError, err.Error())
 			counter.Add(1)
 		}
 		return
 	}
 
 	for range jobs {
-		q.responses.Add(dryRunResponseKey, 0)
+		s.responses.Add(dryRunResponseKey, 0)
 		counter.Add(1)
 	}
 }
 
-func (q sarin) workerDryRunNoStatsWithDynamic(
+func (s sarin) workerDryRunNoStatsWithDynamic(
 	jobs <-chan struct{},
 	req *fasthttp.Request,
 	requestGenerator RequestGenerator,
+	nextClientIndex clientIndexGenerator,
+	bindScriptProxy func(int),
 	counter *atomic.Uint64,
-	sendMessage messageSender,
+	sendLog runtimeLogger,
 ) {
 	for range jobs {
 		req.Reset()
+		// Nothing is sent, this only binds a proxy for the scripts' http.* calls.
+		bindScriptProxy(nextClientIndex())
 		if err := requestGenerator(req); err != nil {
-			sendMessage(runtimeMessageLevelError, err.Error())
+			sendLog(runtimeLogLevelError, err.Error())
 		}
 		counter.Add(1)
 	}
 }
 
-func (q sarin) workerDryRunNoStatsWithStatic(
+func (s sarin) workerDryRunNoStatsWithStatic(
 	jobs <-chan struct{},
 	req *fasthttp.Request,
 	requestGenerator RequestGenerator,
 	counter *atomic.Uint64,
-	sendMessage messageSender,
+	sendLog runtimeLogger,
 ) {
 	if err := requestGenerator(req); err != nil {
-		sendMessage(runtimeMessageLevelError, err.Error())
+		sendLog(runtimeLogLevelError, err.Error())
 	}
 
 	for range jobs {

internal/script/chain.go

@@ -91,6 +91,16 @@ func (t *Transformer) Transform(req *RequestData) error {
 	return nil
 }
 
+// SetHTTPDoer sets the doer that the scripts' http.* calls are sent through.
+func (t *Transformer) SetHTTPDoer(doer HTTPDoer) {
+	for _, engine := range t.luaEngines {
+		engine.SetHTTPDoer(doer)
+	}
+	for _, engine := range t.jsEngines {
+		engine.SetHTTPDoer(doer)
+	}
+}
+
 // Close releases all engine resources.
 func (t *Transformer) Close() {
 	for _, engine := range t.luaEngines {

internal/script/http.go

@@ -0,0 +1,133 @@
+package script
+
+import (
+	"math"
+	"net/http"
+	"strconv"
+	"strings"
+	"time"
+
+	"go.aykhans.me/sarin/internal/types"
+)
+
+// HTTPRequest is a request made by a script through the http.* functions.
+type HTTPRequest struct {
+	Method       string
+	URL          string
+	Headers      map[string][]string
+	Params       map[string][]string
+	Cookies      map[string][]string
+	Body         string
+	Timeout      time.Duration // zero means the doer's default timeout
+	Insecure     bool
+	MaxRedirects int
+}
+
+// HTTPResponse is the response returned to a script by the http.* functions.
+type HTTPResponse struct {
+	Status  int
+	Headers map[string][]string
+	Body    string
+}
+
+// Header returns the first value of the named header, matching the name case-insensitively.
+func (r *HTTPResponse) Header(name string) (string, bool) {
+	for key, values := range r.Headers {
+		if strings.EqualFold(key, name) && len(values) > 0 {
+			return values[0], true
+		}
+	}
+	return "", false
+}
+
+// Cookie returns the value of the named cookie from the Set-Cookie headers.
+func (r *HTTPResponse) Cookie(name string) (string, bool) {
+	for key, values := range r.Headers {
+		if !strings.EqualFold(key, "Set-Cookie") {
+			continue
+		}
+		for _, line := range values {
+			if cookie, err := http.ParseSetCookie(line); err == nil && cookie.Name == name {
+				return cookie.Value, true
+			}
+		}
+	}
+	return "", false
+}
+
+// HTTPDoer sends the HTTP requests that scripts make.
+type HTTPDoer interface {
+	Do(req *HTTPRequest) (*HTTPResponse, error)
+}
+
+// httpDefaultMethod is used when the options set no method.
+const httpDefaultMethod = http.MethodGet
+
+// httpMaxRedirectsLimit is the highest maxRedirects a script may ask for.
+const httpMaxRedirectsLimit = 100
+
+// Option keys accepted by the http function.
+const (
+	httpOptionMethod       = "method"
+	httpOptionHeaders      = "headers"
+	httpOptionParams       = "params"
+	httpOptionCookies      = "cookies"
+	httpOptionBody         = "body"
+	httpOptionTimeout      = "timeout"
+	httpOptionInsecure     = "insecure"
+	httpOptionMaxRedirects = "maxRedirects"
+)
+
+// httpBridge connects http to the doer. Calls only work while transform runs.
+type httpBridge struct {
+	doer   HTTPDoer
+	active bool
+}
+
+// It can return the following errors:
+//   - types.ErrScriptHTTPOutsideTransform
+//   - types.ErrScriptHTTPUnavailable
+//   - types.ErrScriptHTTPMethodEmpty
+//   - any error returned by the doer
+func (b *httpBridge) do(req *HTTPRequest) (*HTTPResponse, error) {
+	if !b.active {
+		return nil, types.ErrScriptHTTPOutsideTransform
+	}
+	if b.doer == nil {
+		return nil, types.ErrScriptHTTPUnavailable
+	}
+	if req.Method == "" {
+		return nil, types.ErrScriptHTTPMethodEmpty
+	}
+	return b.doer.Do(req)
+}
+
+// parseHTTPMaxRedirects checks that the redirect limit is a non-negative whole number.
+// It can return the following errors:
+//   - types.ScriptHTTPOptionError
+func parseHTTPMaxRedirects(count float64) (int, error) {
+	if math.IsNaN(count) || count < 0 || count > httpMaxRedirectsLimit || count != math.Trunc(count) {
+		return 0, types.NewScriptHTTPOptionError(
+			httpOptionMaxRedirects,
+			types.NewScriptTypeError(
+				"a whole number between 0 and "+strconv.Itoa(httpMaxRedirectsLimit),
+				strconv.FormatFloat(count, 'g', -1, 64),
+			),
+		)
+	}
+	return int(count), nil
+}
+
+// parseHTTPTimeout parses a Go duration string such as "500ms" or "2s".
+// It can return the following errors:
+//   - types.ScriptHTTPOptionError
+func parseHTTPTimeout(value string) (time.Duration, error) {
+	timeout, err := time.ParseDuration(value)
+	if err != nil {
+		return 0, types.NewScriptHTTPOptionError(httpOptionTimeout, err)
+	}
+	if timeout <= 0 {
+		return 0, types.NewScriptHTTPOptionError(httpOptionTimeout, types.NewScriptTypeError("a duration greater than 0", value))
+	}
+	return timeout, nil
+}

internal/script/js.go

@@ -2,6 +2,9 @@ package script
 
 import (
 	"errors"
+	"fmt"
+	"reflect"
+	"strconv"
 
 	"github.com/dop251/goja"
 	"go.aykhans.me/sarin/internal/types"
@@ -11,8 +14,15 @@ import (
 type JsEngine struct {
 	runtime   *goja.Runtime
 	transform goja.Callable
+	jsonParse goja.Callable
+	// errorConstructor is the built-in Error, captured before the script can replace it.
+	errorConstructor goja.Value
+	http             httpBridge
 }
 
+// promiseType is what a transform returns when it is declared async or as a generator.
+var promiseType = reflect.TypeFor[*goja.Promise]()
+
 // NewJsEngine creates a new JavaScript script engine with the given script content.
 // The script must define a global `transform` function that takes a request object
 // and returns the modified request object.
@@ -29,11 +39,16 @@ type JsEngine struct {
 //   - types.ScriptExecutionError
 func NewJsEngine(scriptContent string) (*JsEngine, error) {
 	vm := goja.New()
+	engine := &JsEngine{runtime: vm}
+
+	// Register the globals before running the script so its functions can use them
+	if err := engine.registerHTTP(); err != nil {
+		return nil, types.NewScriptExecutionError("JavaScript", err)
+	}
 
 	// Execute the script to define the transform function
-	_, err := vm.RunString(scriptContent)
+	if _, err := vm.RunString(scriptContent); err != nil {
-	if err != nil {
+		return nil, types.NewScriptExecutionError("JavaScript", engine.exceptionError(err))
-		return nil, types.NewScriptExecutionError("JavaScript", err)
 	}
 
 	// Get the transform function
@@ -47,23 +62,43 @@ func NewJsEngine(scriptContent string) (*JsEngine, error) {
 		return nil, types.NewScriptExecutionError("JavaScript", errors.New("'transform' must be a function"))
 	}
 
-	return &JsEngine{
+	// A generator returns an iterator, which is an ordinary object to Go, so the
-		runtime:   vm,
+	// call cannot tell it apart and the declaration is the only thing left to read.
-		transform: transform,
+	if isGeneratorFunction(vm, transformVal) {
-	}, nil
+		return nil, types.ErrScriptTransformAsync
+	}
+
+	engine.transform = transform
+
+	return engine, nil
+}
+
+// SetHTTPDoer sets the doer that the script's http.* calls are sent through.
+func (e *JsEngine) SetHTTPDoer(doer HTTPDoer) {
+	e.http.doer = doer
 }
 
 // Transform executes the JavaScript transform function with the given request data.
 // It can return the following errors:
 //   - types.ScriptExecutionError
 func (e *JsEngine) Transform(req *RequestData) error {
+	e.http.active = true
+	defer func() { e.http.active = false }()
+
 	// Convert RequestData to JavaScript object
 	reqObj := e.requestDataToObject(req)
 
 	// Call transform(req)
 	result, err := e.transform(goja.Undefined(), reqObj)
 	if err != nil {
-		return types.NewScriptExecutionError("JavaScript", err)
+		return types.NewScriptExecutionError("JavaScript", e.exceptionError(err))
+	}
+
+	// An async or generator transform returns a promise nothing ever awaits, and a promise
+	// carries none of the request fields, so the request would go out untransformed.
+	// ExportType reads the type alone, while Export would run every getter on the result.
+	if result.ExportType() == promiseType {
+		return types.ErrScriptTransformAsync
 	}
 
 	// Update RequestData from the returned object
@@ -79,6 +114,8 @@ func (e *JsEngine) Close() {
 	// goja doesn't have an explicit close method, but we can help GC
 	e.runtime = nil
 	e.transform = nil
+	e.jsonParse = nil
+	e.errorConstructor = nil
 }
 
 // requestDataToObject converts RequestData to a goja Value (JavaScript object).
@@ -124,37 +161,70 @@ func (e *JsEngine) objectToRequestData(val goja.Value, req *RequestData) error {
 		return types.ErrScriptTransformReturnObject
 	}
 
-	// Method
+	// Reading a field runs the script's own getters and toString, which throw as a Go
-	if v := obj.Get("method"); v != nil && !goja.IsUndefined(v) {
+	// panic outside goja's execution context, so the whole read runs inside Try.
-		req.Method = v.String()
+	var fieldErr error
+	if thrown := e.runtime.Try(func() {
+		// Method
+		if v := obj.Get("method"); v != nil && !goja.IsUndefined(v) && !goja.IsNull(v) {
+			req.Method = v.String()
+		}
+
+		// Path
+		if v := obj.Get("path"); v != nil && !goja.IsUndefined(v) && !goja.IsNull(v) {
+			req.Path = v.String()
+		}
+
+		// Body
+		if v := obj.Get("body"); v != nil && !goja.IsUndefined(v) && !goja.IsNull(v) {
+			req.Body = v.String()
+		}
+
+		// Headers
+		if v := obj.Get("headers"); v != nil && !goja.IsUndefined(v) && !goja.IsNull(v) {
+			values, err := objectField("headers", v)
+			if err != nil {
+				fieldErr = err
+				return
+			}
+			req.Headers = e.objectToStringSliceMap(values)
+		}
+
+		// Params
+		if v := obj.Get("params"); v != nil && !goja.IsUndefined(v) && !goja.IsNull(v) {
+			values, err := objectField("params", v)
+			if err != nil {
+				fieldErr = err
+				return
+			}
+			req.Params = e.objectToStringSliceMap(values)
+		}
+
+		// Cookies
+		if v := obj.Get("cookies"); v != nil && !goja.IsUndefined(v) && !goja.IsNull(v) {
+			values, err := objectField("cookies", v)
+			if err != nil {
+				fieldErr = err
+				return
+			}
+			req.Cookies = e.objectToStringSliceMap(values)
+		}
+	}); thrown != nil {
+		return e.exceptionError(thrown)
 	}
 
-	// Path
+	return fieldErr
-	if v := obj.Get("path"); v != nil && !goja.IsUndefined(v) {
+}
-		req.Path = v.String()
-	}
 
-	// Body
+// objectField rejects anything that is not a plain object, since reading keys off an
-	if v := obj.Get("body"); v != nil && !goja.IsUndefined(v) {
+// array or a boxed string yields headers named after indexes and off a Date yields none.
-		req.Body = v.String()
+// A Map, a Set and a typed array still pass, so the field is emptied rather than refused.
+func objectField(name string, value goja.Value) (*goja.Object, error) {
+	obj, ok := value.(*goja.Object)
+	if !ok || obj.ClassName() != "Object" {
+		return nil, fmt.Errorf("%s must be an object", name)
 	}
-
+	return obj, nil
-	// Headers
-	if v := obj.Get("headers"); v != nil && !goja.IsUndefined(v) && !goja.IsNull(v) {
-		req.Headers = e.objectToStringSliceMap(v.ToObject(e.runtime))
-	}
-
-	// Params
-	if v := obj.Get("params"); v != nil && !goja.IsUndefined(v) && !goja.IsNull(v) {
-		req.Params = e.objectToStringSliceMap(v.ToObject(e.runtime))
-	}
-
-	// Cookies
-	if v := obj.Get("cookies"); v != nil && !goja.IsUndefined(v) && !goja.IsNull(v) {
-		req.Cookies = e.objectToStringSliceMap(v.ToObject(e.runtime))
-	}
-
-	return nil
 }
 
 // stringSliceToArray converts a Go []string to a JavaScript array.
@@ -176,23 +246,78 @@ func (e *JsEngine) objectToStringSliceMap(obj *goja.Object) map[string][]string
 	result := make(map[string][]string)
 	for _, key := range obj.Keys() {
 		v := obj.Get(key)
-		if v == nil || goja.IsUndefined(v) || goja.IsNull(v) {
-			continue
-		}
 
 		// Check if it's an array
-		if arr, ok := v.Export().([]any); ok {
+		if arr, ok := v.(*goja.Object); ok && arr.ClassName() == "Array" {
-			var values []string
+			length := int(arr.Get("length").ToInteger())
-			for _, item := range arr {
+			values := make([]string, 0, length)
-				if s, ok := item.(string); ok {
+			for i := range length {
-					values = append(values, s)
+				if text, ok := jsStringValue(arr.Get(strconv.Itoa(i))); ok {
+					values = append(values, text)
 				}
 			}
 			result[key] = values
-		} else {
+			continue
-			// Single value - wrap in slice
+		}
-			result[key] = []string{v.String()}
+
+		// Single value, wrap it in a slice
+		if text, ok := jsStringValue(v); ok {
+			result[key] = []string{text}
 		}
 	}
 	return result
 }
+
+// exceptionError keeps the thrown value's message without goja's stack frame.
+// Stringifying runs through Runtime.Try because a thrown value with no usable
+// toString makes goja panic outside its own execution context.
+func (e *JsEngine) exceptionError(err error) error {
+	var exception *goja.Exception
+	if !errors.As(err, &exception) {
+		return err
+	}
+
+	var message string
+	if thrown := e.runtime.Try(func() { message = exception.Value().String() }); thrown != nil {
+		message = "unprintable thrown value"
+	}
+	return errors.New(message)
+}
+
+// jsStringValue renders a JavaScript primitive the way the script would see it.
+// Objects, arrays and functions have no useful text form, so they are skipped.
+func jsStringValue(v goja.Value) (string, bool) {
+	if v == nil || goja.IsUndefined(v) || goja.IsNull(v) {
+		return "", false
+	}
+	if _, isObject := v.(*goja.Object); isObject {
+		return "", false
+	}
+	return v.String(), true
+}
+
+// isGeneratorFunction reports whether a function is declared with a star.
+// The name comes from the script's own prototype chain, so a script can falsify it either way.
+// Reading it can run a script getter, so the whole walk stays inside Try.
+func isGeneratorFunction(runtime *goja.Runtime, value goja.Value) bool {
+	var name string
+	thrown := runtime.Try(func() {
+		obj := value.ToObject(runtime)
+		if obj == nil {
+			return
+		}
+		constructor := obj.Get("constructor")
+		if constructor == nil || goja.IsUndefined(constructor) || goja.IsNull(constructor) {
+			return
+		}
+		constructorObj := constructor.ToObject(runtime)
+		if constructorObj == nil {
+			return
+		}
+		if value := constructorObj.Get("name"); value != nil {
+			name = value.String()
+		}
+	})
+
+	return thrown == nil && name == "GeneratorFunction"
+}

internal/script/js_http.go

@@ -0,0 +1,220 @@
+package script
+
+import (
+	"errors"
+
+	"github.com/dop251/goja"
+	"go.aykhans.me/sarin/internal/types"
+)
+
+// registerHTTP defines the global http function.
+func (e *JsEngine) registerHTTP() error {
+	rt := e.runtime
+
+	jsonParse, ok := goja.AssertFunction(rt.Get("JSON").ToObject(rt).Get("parse"))
+	if !ok {
+		return errors.New("JSON.parse is not available")
+	}
+	e.jsonParse = jsonParse
+	e.errorConstructor = rt.Get("Error")
+
+	return rt.Set("http", func(call goja.FunctionCall) goja.Value {
+		return e.httpCall(call.Argument(0), call.Argument(1))
+	})
+}
+
+func (e *JsEngine) httpCall(urlValue, optsValue goja.Value) goja.Value {
+	rt := e.runtime
+
+	url, ok := urlValue.Export().(string)
+	if !ok {
+		panic(rt.NewTypeError("http: url must be a string, got %s", jsTypeName(urlValue)))
+	}
+	req := &HTTPRequest{Method: httpDefaultMethod, URL: url}
+
+	if !goja.IsUndefined(optsValue) && !goja.IsNull(optsValue) {
+		opts, ok := optsValue.(*goja.Object)
+		if !ok {
+			panic(rt.NewTypeError("http: options must be an object, got %s", jsTypeName(optsValue)))
+		}
+		if err := e.parseHTTPOptions(opts, req); err != nil {
+			e.throw(err)
+		}
+	}
+
+	resp, err := e.http.do(req)
+	if err != nil {
+		e.throw(err)
+	}
+
+	return e.httpResponseToObject(resp)
+}
+
+// parseHTTPOptions fills req from a JavaScript options object.
+// It can return the following errors:
+//   - types.ScriptHTTPOptionError
+func (e *JsEngine) parseHTTPOptions(opts *goja.Object, req *HTTPRequest) error {
+	for _, name := range opts.Keys() {
+		value := opts.Get(name)
+		if goja.IsUndefined(value) {
+			continue
+		}
+
+		switch name {
+		case httpOptionMethod:
+			method, ok := value.Export().(string)
+			if !ok {
+				return types.NewScriptHTTPOptionError(name, types.NewScriptTypeError("string", jsTypeName(value)))
+			}
+
+			req.Method = method
+		case httpOptionHeaders, httpOptionParams, httpOptionCookies:
+			object, ok := value.(*goja.Object)
+			if !ok {
+				return types.NewScriptHTTPOptionError(name, types.NewScriptTypeError("object", jsTypeName(value)))
+			}
+
+			values := e.objectToStringSliceMap(object)
+			switch name {
+			case httpOptionHeaders:
+				req.Headers = values
+			case httpOptionParams:
+				req.Params = values
+			default:
+				req.Cookies = values
+			}
+		case httpOptionBody:
+			body, ok := value.Export().(string)
+			if !ok {
+				return types.NewScriptHTTPOptionError(name, types.NewScriptTypeError("string", jsTypeName(value)))
+			}
+
+			req.Body = body
+		case httpOptionTimeout:
+			timeout, ok := value.Export().(string)
+			if !ok {
+				return types.NewScriptHTTPOptionError(name, types.NewScriptTypeError("duration string", jsTypeName(value)))
+			}
+
+			var err error
+			if req.Timeout, err = parseHTTPTimeout(timeout); err != nil {
+				return err
+			}
+		case httpOptionInsecure:
+			flag, ok := value.Export().(bool)
+			if !ok {
+				return types.NewScriptHTTPOptionError(name, types.NewScriptTypeError("boolean", jsTypeName(value)))
+			}
+
+			req.Insecure = flag
+		case httpOptionMaxRedirects:
+			count, ok := numberValue(value)
+			if !ok {
+				return types.NewScriptHTTPOptionError(name, types.NewScriptTypeError("number", jsTypeName(value)))
+			}
+
+			var err error
+			if req.MaxRedirects, err = parseHTTPMaxRedirects(count); err != nil {
+				return err
+			}
+		default:
+			return types.NewScriptHTTPOptionError(name, types.ErrScriptHTTPUnknownOption)
+		}
+	}
+	return nil
+}
+
+// httpResponseToObject converts a response to a JavaScript object.
+func (e *JsEngine) httpResponseToObject(resp *HTTPResponse) *goja.Object {
+	rt := e.runtime
+	obj := rt.NewObject()
+
+	headers := rt.NewObject()
+	for key, values := range resp.Headers {
+		_ = headers.Set(key, e.stringSliceToArray(values))
+	}
+
+	lookup := func(find func(string) (string, bool)) func(goja.FunctionCall) goja.Value {
+		return func(call goja.FunctionCall) goja.Value {
+			name, ok := call.Argument(0).Export().(string)
+			if !ok {
+				panic(rt.NewTypeError("name must be a string, got %s", jsTypeName(call.Argument(0))))
+			}
+			if value, ok := find(name); ok {
+				return rt.ToValue(value)
+			}
+			return goja.Null()
+		}
+	}
+
+	_ = obj.Set("status", resp.Status)
+	_ = obj.Set("headers", headers)
+	_ = obj.Set("body", resp.Body)
+	_ = obj.Set("header", lookup(resp.Header))
+	_ = obj.Set("cookie", lookup(resp.Cookie))
+	_ = obj.Set("json", func(goja.FunctionCall) goja.Value {
+		value, err := e.jsonParse(goja.Undefined(), rt.ToValue(resp.Body))
+		if err != nil {
+			panic(err)
+		}
+		return value
+	})
+	// body is a JavaScript string, so bytes that are not valid UTF-8 reach the script
+	// only through this.
+	_ = obj.Set("bytes", func(goja.FunctionCall) goja.Value {
+		buffer := rt.NewArrayBuffer([]byte(resp.Body))
+		value, err := rt.New(rt.Get("Uint8Array").ToObject(rt), rt.ToValue(buffer))
+		if err != nil {
+			panic(err)
+		}
+		return value
+	})
+
+	return obj
+}
+
+// jsTypeName returns a short type name for error messages.
+func jsTypeName(value goja.Value) string {
+	switch {
+	case value == nil || goja.IsUndefined(value):
+		return "undefined"
+	case goja.IsNull(value):
+		return "null"
+	}
+	switch value.Export().(type) {
+	case string:
+		return "string"
+	case bool:
+		return "boolean"
+	case int64, float64:
+		return "number"
+	case []any:
+		return "array"
+	default:
+		if _, ok := goja.AssertFunction(value); ok {
+			return "function"
+		}
+		return "object"
+	}
+}
+
+// throw raises err as a plain JavaScript Error instead of a GoError.
+func (e *JsEngine) throw(err error) {
+	errorValue, newErr := e.runtime.New(e.errorConstructor, e.runtime.ToValue(err.Error()))
+	if newErr != nil {
+		panic(e.runtime.NewGoError(err))
+	}
+	panic(errorValue)
+}
+
+// numberValue reports whether value is a JavaScript number, and returns it.
+func numberValue(value goja.Value) (float64, bool) {
+	switch number := value.Export().(type) {
+	case int64:
+		return float64(number), true
+	case float64:
+		return number, true
+	default:
+		return 0, false
+	}
+}

internal/script/lua.go

@@ -11,6 +11,7 @@ import (
 type LuaEngine struct {
 	state     *lua.LState
 	transform *lua.LFunction
+	http      httpBridge
 }
 
 // NewLuaEngine creates a new Lua script engine with the given script content.
@@ -29,6 +30,11 @@ type LuaEngine struct {
 //   - types.ScriptExecutionError
 func NewLuaEngine(scriptContent string) (*LuaEngine, error) {
 	L := lua.NewState()
+	engine := &LuaEngine{state: L}
+
+	// Register the globals before running the script so its functions can use them
+	engine.registerHTTP()
+	registerLuaJSON(L)
 
 	// Execute the script to define the transform function
 	if err := L.DoString(scriptContent); err != nil {
@@ -42,17 +48,23 @@ func NewLuaEngine(scriptContent string) (*LuaEngine, error) {
 		L.Close()
 		return nil, types.ErrScriptTransformMissing
 	}
+	engine.transform = transform.(*lua.LFunction)
 
-	return &LuaEngine{
+	return engine, nil
-		state:     L,
+}
-		transform: transform.(*lua.LFunction),
+
-	}, nil
+// SetHTTPDoer sets the doer that the script's http.* calls are sent through.
+func (e *LuaEngine) SetHTTPDoer(doer HTTPDoer) {
+	e.http.doer = doer
 }
 
 // Transform executes the Lua transform function with the given request data.
 // It can return the following errors:
 //   - types.ScriptExecutionError
 func (e *LuaEngine) Transform(req *RequestData) error {
+	e.http.active = true
+	defer func() { e.http.active = false }()
+
 	// Convert RequestData to Lua table
 	reqTable := e.requestDataToTable(req)
 
@@ -93,39 +105,23 @@ func (e *LuaEngine) requestDataToTable(req *RequestData) *lua.LTable {
 	t.RawSetString("path", lua.LString(req.Path))
 	t.RawSetString("body", lua.LString(req.Body))
 
-	// Headers (map[string][]string -> table of arrays)
+	t.RawSetString("headers", stringSliceMapToTable(L, req.Headers))
-	headers := L.NewTable()
+	t.RawSetString("params", stringSliceMapToTable(L, req.Params))
-	for k, values := range req.Headers {
+	t.RawSetString("cookies", stringSliceMapToTable(L, req.Cookies))
-		arr := L.NewTable()
+
+	return t
+}
+
+// stringSliceMapToTable converts a Go map[string][]string to a Lua table of arrays.
+func stringSliceMapToTable(state *lua.LState, m map[string][]string) *lua.LTable {
+	t := state.NewTable()
+	for k, values := range m {
+		arr := state.NewTable()
 		for _, v := range values {
 			arr.Append(lua.LString(v))
 		}
-		headers.RawSetString(k, arr)
+		t.RawSetString(k, arr)
 	}
-	t.RawSetString("headers", headers)
-
-	// Params (map[string][]string -> table of arrays)
-	params := L.NewTable()
-	for k, values := range req.Params {
-		arr := L.NewTable()
-		for _, v := range values {
-			arr.Append(lua.LString(v))
-		}
-		params.RawSetString(k, arr)
-	}
-	t.RawSetString("params", params)
-
-	// Cookies (map[string][]string -> table of arrays)
-	cookies := L.NewTable()
-	for k, values := range req.Cookies {
-		arr := L.NewTable()
-		for _, v := range values {
-			arr.Append(lua.LString(v))
-		}
-		cookies.RawSetString(k, arr)
-	}
-	t.RawSetString("cookies", cookies)
-
 	return t
 }
 
@@ -172,20 +168,33 @@ func (e *LuaEngine) tableToStringSliceMap(t *lua.LTable) map[string][]string {
 		}
 		key := string(k.(lua.LString))
 
-		switch v.Type() {
+		if v.Type() == lua.LTTable {
-		case lua.LTString:
+			// Array of values, keys outside 1..n are skipped
-			// Single string value
+			arr := v.(*lua.LTable)
-			result[key] = []string{string(v.(lua.LString))}
+			length := arr.Len()
-		case lua.LTTable:
+			values := make([]string, 0, length)
-			// Array of strings
+			for i := 1; i <= length; i++ {
-			var values []string
+				if text, ok := luaScalarString(arr.RawGetInt(i)); ok {
-			v.(*lua.LTable).ForEach(func(_, item lua.LValue) {
+					values = append(values, text)
-				if item.Type() == lua.LTString {
-					values = append(values, string(item.(lua.LString)))
 				}
-			})
+			}
 			result[key] = values
+			return
+		}
+
+		if text, ok := luaScalarString(v); ok {
+			result[key] = []string{text}
 		}
 	})
 	return result
 }
+
+// luaScalarString renders strings, numbers and booleans as text.
+func luaScalarString(v lua.LValue) (string, bool) {
+	switch v.Type() {
+	case lua.LTString, lua.LTNumber, lua.LTBool:
+		return v.String(), true
+	default:
+		return "", false
+	}
+}

internal/script/lua_http.go

@@ -0,0 +1,142 @@
+package script
+
+import (
+	lua "github.com/yuin/gopher-lua"
+	"go.aykhans.me/sarin/internal/types"
+)
+
+// registerHTTP defines the global http function.
+func (e *LuaEngine) registerHTTP() {
+	L := e.state
+	L.SetGlobal("http", L.NewFunction(func(L *lua.LState) int {
+		return e.httpCall(L, 1)
+	}))
+}
+
+// httpCall sends the request whose URL is at stack position urlIndex and pushes the response.
+func (e *LuaEngine) httpCall(state *lua.LState, urlIndex int) int {
+	req := &HTTPRequest{
+		Method: httpDefaultMethod,
+		URL:    state.CheckString(urlIndex),
+	}
+
+	switch opts := state.Get(urlIndex + 1).(type) {
+	case *lua.LNilType:
+	case *lua.LTable:
+		if err := e.parseHTTPOptions(opts, req); err != nil {
+			state.RaiseError("%s", err.Error())
+		}
+	default:
+		state.ArgError(urlIndex+1, "options must be a table")
+	}
+
+	resp, err := e.http.do(req)
+	if err != nil {
+		state.RaiseError("%s", err.Error())
+	}
+
+	state.Push(httpResponseToTable(state, resp))
+	return 1
+}
+
+// parseHTTPOptions fills req from a Lua options table.
+// It can return the following errors:
+//   - types.ScriptHTTPOptionError
+func (e *LuaEngine) parseHTTPOptions(opts *lua.LTable, req *HTTPRequest) error {
+	var err error
+	opts.ForEach(func(k, v lua.LValue) {
+		if err != nil {
+			return
+		}
+
+		key, ok := k.(lua.LString)
+		if !ok {
+			err = types.NewScriptHTTPOptionError(k.String(), types.ErrScriptHTTPUnknownOption)
+			return
+		}
+
+		switch name := string(key); name {
+		case httpOptionMethod:
+			method, ok := v.(lua.LString)
+			if !ok {
+				err = types.NewScriptHTTPOptionError(name, types.NewScriptTypeError("string", v.Type().String()))
+				return
+			}
+			req.Method = string(method)
+		case httpOptionHeaders, httpOptionParams, httpOptionCookies:
+			table, ok := v.(*lua.LTable)
+			if !ok {
+				err = types.NewScriptHTTPOptionError(name, types.NewScriptTypeError("table", v.Type().String()))
+				return
+			}
+			values := e.tableToStringSliceMap(table)
+			switch name {
+			case httpOptionHeaders:
+				req.Headers = values
+			case httpOptionParams:
+				req.Params = values
+			default:
+				req.Cookies = values
+			}
+		case httpOptionBody:
+			body, ok := v.(lua.LString)
+			if !ok {
+				err = types.NewScriptHTTPOptionError(name, types.NewScriptTypeError("string", v.Type().String()))
+				return
+			}
+			req.Body = string(body)
+		case httpOptionTimeout:
+			timeout, ok := v.(lua.LString)
+			if !ok {
+				err = types.NewScriptHTTPOptionError(name, types.NewScriptTypeError("duration string", v.Type().String()))
+				return
+			}
+			req.Timeout, err = parseHTTPTimeout(string(timeout))
+		case httpOptionInsecure:
+			flag, ok := v.(lua.LBool)
+			if !ok {
+				err = types.NewScriptHTTPOptionError(name, types.NewScriptTypeError("boolean", v.Type().String()))
+				return
+			}
+			req.Insecure = bool(flag)
+		case httpOptionMaxRedirects:
+			count, ok := v.(lua.LNumber)
+			if !ok {
+				err = types.NewScriptHTTPOptionError(name, types.NewScriptTypeError("number", v.Type().String()))
+				return
+			}
+			req.MaxRedirects, err = parseHTTPMaxRedirects(float64(count))
+		default:
+			err = types.NewScriptHTTPOptionError(name, types.ErrScriptHTTPUnknownOption)
+		}
+	})
+	return err
+}
+
+// httpResponseToTable converts a response to a Lua table.
+func httpResponseToTable(state *lua.LState, resp *HTTPResponse) *lua.LTable {
+	t := state.NewTable()
+	t.RawSetString("status", lua.LNumber(resp.Status))
+	t.RawSetString("headers", stringSliceMapToTable(state, resp.Headers))
+	t.RawSetString("body", lua.LString(resp.Body))
+
+	lookup := func(find func(string) (string, bool)) *lua.LFunction {
+		return state.NewFunction(func(L *lua.LState) int {
+			// Last argument, so both res:header() and res.header() work.
+			top := L.GetTop()
+			if top == 0 {
+				L.ArgError(1, "name expected")
+			}
+			if value, ok := find(L.CheckString(top)); ok {
+				L.Push(lua.LString(value))
+			} else {
+				L.Push(lua.LNil)
+			}
+			return 1
+		})
+	}
+	t.RawSetString("header", lookup(resp.Header))
+	t.RawSetString("cookie", lookup(resp.Cookie))
+
+	return t
+}

internal/script/lua_json.go

@@ -0,0 +1,148 @@
+package script
+
+import (
+	"bytes"
+	"encoding/json"
+	"math"
+	"strings"
+
+	lua "github.com/yuin/gopher-lua"
+	"go.aykhans.me/sarin/internal/types"
+)
+
+// registerLuaJSON defines the global json table with encode and decode.
+func registerLuaJSON(state *lua.LState) {
+	module := state.NewTable()
+	module.RawSetString("encode", state.NewFunction(luaJSONEncode))
+	module.RawSetString("decode", state.NewFunction(luaJSONDecode))
+	state.SetGlobal("json", module)
+}
+
+func luaJSONEncode(state *lua.LState) int {
+	value, err := luaToGo(state.CheckAny(1), make(map[*lua.LTable]bool))
+	if err != nil {
+		state.RaiseError("%s", types.NewScriptJSONError("encode", err).Error())
+	}
+
+	var buf bytes.Buffer
+	encoder := json.NewEncoder(&buf)
+	encoder.SetEscapeHTML(false)
+	if err := encoder.Encode(value); err != nil {
+		state.RaiseError("%s", types.NewScriptJSONError("encode", err).Error())
+	}
+
+	state.Push(lua.LString(strings.TrimSuffix(buf.String(), "\n")))
+	return 1
+}
+
+func luaJSONDecode(state *lua.LState) int {
+	var value any
+	if err := json.Unmarshal([]byte(state.CheckString(1)), &value); err != nil {
+		state.RaiseError("%s", types.NewScriptJSONError("decode", err).Error())
+	}
+
+	state.Push(goToLua(state, value))
+	return 1
+}
+
+// luaToGo converts a Lua value to a JSON-encodable Go value.
+// It can return the following errors:
+//   - types.ErrScriptJSONCycle
+//   - types.ScriptTypeError
+func luaToGo(value lua.LValue, visiting map[*lua.LTable]bool) (any, error) {
+	switch v := value.(type) {
+	case *lua.LNilType:
+		return nil, nil
+	case lua.LBool:
+		return bool(v), nil
+	case lua.LNumber:
+		return float64(v), nil
+	case lua.LString:
+		return string(v), nil
+	case *lua.LTable:
+		if visiting[v] {
+			return nil, types.ErrScriptJSONCycle
+		}
+		visiting[v] = true
+		defer delete(visiting, v)
+
+		if length, ok := luaArrayLength(v); ok {
+			array := make([]any, length)
+			for i := range length {
+				item, err := luaToGo(v.RawGetInt(i+1), visiting)
+				if err != nil {
+					return nil, err
+				}
+				array[i] = item
+			}
+			return array, nil
+		}
+
+		object := make(map[string]any)
+		var err error
+		v.ForEach(func(key, item lua.LValue) {
+			if err != nil {
+				return
+			}
+			switch key.(type) {
+			case lua.LString, lua.LNumber:
+			default:
+				err = types.NewScriptTypeError("string or number object key", key.Type().String())
+				return
+			}
+			object[key.String()], err = luaToGo(item, visiting)
+		})
+		if err != nil {
+			return nil, err
+		}
+		return object, nil
+	default:
+		return nil, types.NewScriptTypeError("nil, boolean, number, string or table", value.Type().String())
+	}
+}
+
+// luaArrayLength reports whether t is a non-empty sequence with keys exactly 1..n.
+func luaArrayLength(t *lua.LTable) (int, bool) {
+	count := 0
+	isArray := true
+	maxKey := 0.0
+	t.ForEach(func(key, _ lua.LValue) {
+		count++
+		number, ok := key.(lua.LNumber)
+		if !ok || float64(number) < 1 || float64(number) != math.Trunc(float64(number)) {
+			isArray = false
+			return
+		}
+		maxKey = max(maxKey, float64(number))
+	})
+	if !isArray || count == 0 || maxKey != float64(count) {
+		return 0, false
+	}
+	return count, true
+}
+
+// goToLua converts a value produced by encoding/json to a Lua value.
+func goToLua(state *lua.LState, value any) lua.LValue {
+	switch v := value.(type) {
+	case bool:
+		return lua.LBool(v)
+	case float64:
+		return lua.LNumber(v)
+	case string:
+		return lua.LString(v)
+	case []any:
+		t := state.CreateTable(len(v), 0)
+		for i, item := range v {
+			t.RawSetInt(i+1, goToLua(state, item))
+		}
+		return t
+	case map[string]any:
+		t := state.CreateTable(0, len(v))
+		for key, item := range v {
+			t.RawSetString(key, goToLua(state, item))
+		}
+		return t
+	default:
+		return lua.LNil
+	}
+}

internal/script/script.go

@@ -31,6 +31,9 @@ type Engine interface {
 	// The script should modify the RequestData and return it.
 	Transform(req *RequestData) error
 
+	// SetHTTPDoer sets the doer that the script's http.* calls are sent through.
+	SetHTTPDoer(doer HTTPDoer)
+
 	// Close releases any resources held by the engine.
 	Close()
 }
@@ -69,7 +72,7 @@ func LoadSource(ctx context.Context, source string, engineType EngineType) (*Sou
 
 	switch {
 	case strings.HasPrefix(source, "@@"):
-		// Escaped @ - it's an inline script starting with literal @
+		// Escaped @: an inline script starting with a literal @
 		content = source[1:] // Remove first @, keep the rest
 	case strings.HasPrefix(source, "@"):
 		// File or URL reference
@@ -125,7 +128,7 @@ func ValidateScript(ctx context.Context, source string, engineType EngineType) e
 		return err
 	}
 
-	// Try to create an engine - this validates syntax and transform function
+	// Creating an engine validates the syntax and the transform function
 	var engine Engine
 	switch engineType {
 	case EngineTypeLua:
@@ -140,7 +143,7 @@ func ValidateScript(ctx context.Context, source string, engineType EngineType) e
 		return err
 	}
 
-	// Clean up the engine - we only needed it for validation
+	// The engine was only needed for validation
 	engine.Close()
 	return nil
 }
@@ -168,10 +171,18 @@ func fetchURL(ctx context.Context, url string) (string, error) {
 		return "", types.NewHTTPStatusError(url, resp.StatusCode, resp.Status)
 	}
 
-	data, err := io.ReadAll(resp.Body)
+	// A declared size above the limit is refused before anything is read.
+	if resp.ContentLength > types.RemoteFetchLimit {
+		return "", types.NewHTTPFetchError(url, types.ErrRemoteFileTooLarge)
+	}
+
+	data, err := io.ReadAll(io.LimitReader(resp.Body, types.RemoteFetchLimit+1))
 	if err != nil {
 		return "", types.NewHTTPFetchError(url, err)
 	}
+	if len(data) > types.RemoteFetchLimit {
+		return "", types.NewHTTPFetchError(url, types.ErrRemoteFileTooLarge)
+	}
 
 	return string(data), nil
 }

internal/types/byte_size.go

@@ -0,0 +1,87 @@
+package types
+
+import (
+	"math"
+	"strconv"
+	"strings"
+)
+
+// ByteSizeLimit is the largest size any option may ask for. A limit is also the most
+// memory one response may take, so it stays well under what a machine can hold.
+const ByteSizeLimit = 1 << 30 // 1 GiB
+
+// RemoteFetchLimit bounds a file sarin downloads for itself, such as a config file or a script.
+const RemoteFetchLimit = 64 << 20 // 64 MiB
+
+// byteSizeUnits run from the largest scale down, so formatting picks the largest unit
+// that fits. A bare "K" is out: the common libraries disagree on whether it counts
+// 1000 or 1024 bytes.
+var byteSizeUnits = []struct {
+	suffix string
+	scale  uint64
+}{
+	{"TiB", 1 << 40},
+	{"TB", 1000 * 1000 * 1000 * 1000},
+	{"GiB", 1 << 30},
+	{"GB", 1000 * 1000 * 1000},
+	{"MiB", 1 << 20},
+	{"MB", 1000 * 1000},
+	{"KiB", 1 << 10},
+	{"KB", 1000},
+	{"B", 1},
+}
+
+// ParseByteSize reads a byte count, with or without a unit suffix.
+// It can return the following errors:
+//   - ErrByteSizeInvalid
+func ParseByteSize(value string) (uint64, error) {
+	text := strings.TrimSpace(value)
+
+	// The suffix is split off by index, so no case mapping can shift the digits.
+	digitsEnd := len(text)
+	for digitsEnd > 0 && isASCIILetter(text[digitsEnd-1]) {
+		digitsEnd--
+	}
+
+	scale := uint64(1)
+	if suffix := text[digitsEnd:]; suffix != "" {
+		unitScale, ok := byteSizeScale(suffix)
+		if !ok {
+			return 0, ErrByteSizeInvalid
+		}
+		scale = unitScale
+	}
+
+	size, err := strconv.ParseUint(strings.TrimSpace(text[:digitsEnd]), 10, 64)
+	if err != nil {
+		return 0, ErrByteSizeInvalid
+	}
+	if size > math.MaxUint64/scale {
+		return 0, ErrByteSizeInvalid
+	}
+	return size * scale, nil
+}
+
+// FormatByteSize renders a byte count so that ParseByteSize reads back the same value.
+func FormatByteSize(size uint64) string {
+	for _, unit := range byteSizeUnits {
+		if unit.scale > 1 && size >= unit.scale && size%unit.scale == 0 {
+			return strconv.FormatUint(size/unit.scale, 10) + unit.suffix
+		}
+	}
+	return strconv.FormatUint(size, 10)
+}
+
+// byteSizeScale looks up a unit suffix, ignoring case.
+func byteSizeScale(suffix string) (uint64, bool) {
+	for _, unit := range byteSizeUnits {
+		if strings.EqualFold(suffix, unit.suffix) {
+			return unit.scale, true
+		}
+	}
+	return 0, false
+}
+
+func isASCIILetter(char byte) bool {
+	return (char >= 'a' && char <= 'z') || (char >= 'A' && char <= 'Z')
+}

internal/types/errors.go

@@ -10,6 +10,17 @@ import (
 
 var (
 	errNoError = errors.New("no error (internal)")
+
+	ErrByteSizeInvalid = errors.New(
+		"invalid value for size, expected a whole number of bytes or a whole number with a unit: " +
+			"B, KB, MB, GB, TB (1000 based) or KiB, MiB, GiB, TiB (1024 based), e.g. '1048576', '10MiB', '2MB'",
+	)
+
+	ErrRemoteFileTooLarge = errors.New("remote file exceeds " + FormatByteSize(RemoteFetchLimit))
+
+	ErrResponseBodyTooLarge = errors.New("response body exceeds the body limit")
+
+	ErrYAMLMultipleDocuments = errors.New("expected a single YAML document, but found more than one")
 )
 
 type FieldParseError struct {
@@ -297,6 +308,27 @@ func (e CLIUnexpectedArgsError) Error() string {
 
 // ======================================== Config File ========================================
 
+// ConfigFileError names the file a parse error came from, which nested configFile chains lose.
+type ConfigFileError struct {
+	Path  string
+	error error
+}
+
+func NewConfigFileError(path string, err error) ConfigFileError {
+	if err == nil {
+		err = errNoError
+	}
+	return ConfigFileError{path, err}
+}
+
+func (e ConfigFileError) Error() string {
+	return e.error.Error()
+}
+
+func (e ConfigFileError) Unwrap() error {
+	return e.error
+}
+
 type ConfigFileReadError struct {
 	error error
 }
@@ -318,6 +350,8 @@ func (e ConfigFileReadError) Unwrap() error {
 
 // ======================================== Proxy ========================================
 
+var ErrProxyNoContextDialer = errors.New("SOCKS5 dialer does not support timeouts")
+
 type ProxyUnsupportedSchemeError struct {
 	Scheme string
 }
@@ -400,9 +434,90 @@ var (
 	ErrScriptSourceEmpty           = errors.New("script source cannot be empty after @")
 	ErrScriptTransformMissing      = errors.New("script must define a global 'transform' function")
 	ErrScriptTransformReturnObject = errors.New("transform function must return an object")
+	ErrScriptTransformAsync        = errors.New("transform function must be synchronous, async and generator functions are not supported")
 	ErrScriptURLNoHost             = errors.New("script URL must have a host")
+	ErrScriptHTTPOutsideTransform  = errors.New("http functions can only be called while transform is running")
+	ErrScriptHTTPUnavailable       = errors.New("http client is not available")
+	ErrScriptHTTPMethodEmpty       = errors.New("http method cannot be empty")
+	ErrScriptHTTPURLInvalid        = errors.New("URL must be an absolute http or https URL")
+	ErrScriptHTTPUnknownOption     = errors.New("unknown option")
+	ErrScriptJSONCycle             = errors.New("cannot encode a table that contains itself")
 )
 
+type ScriptTypeError struct {
+	Expected string
+	Got      string
+}
+
+func NewScriptTypeError(expected, got string) ScriptTypeError {
+	return ScriptTypeError{expected, got}
+}
+
+func (e ScriptTypeError) Error() string {
+	return fmt.Sprintf("expected %s, got %s", e.Expected, e.Got)
+}
+
+type ScriptHTTPOptionError struct {
+	Option string
+	Err    error
+}
+
+func NewScriptHTTPOptionError(option string, err error) ScriptHTTPOptionError {
+	if err == nil {
+		err = errNoError
+	}
+	return ScriptHTTPOptionError{option, err}
+}
+
+func (e ScriptHTTPOptionError) Error() string {
+	return fmt.Sprintf("http option %q: %v", e.Option, e.Err)
+}
+
+func (e ScriptHTTPOptionError) Unwrap() error {
+	return e.Err
+}
+
+type ScriptHTTPRequestError struct {
+	Method string
+	URL    string
+	Err    error
+}
+
+func NewScriptHTTPRequestError(method, url string, err error) ScriptHTTPRequestError {
+	if err == nil {
+		err = errNoError
+	}
+	return ScriptHTTPRequestError{method, url, err}
+}
+
+func (e ScriptHTTPRequestError) Error() string {
+	return fmt.Sprintf("http %s %s: %v", e.Method, e.URL, e.Err)
+}
+
+func (e ScriptHTTPRequestError) Unwrap() error {
+	return e.Err
+}
+
+type ScriptJSONError struct {
+	Op  string
+	Err error
+}
+
+func NewScriptJSONError(op string, err error) ScriptJSONError {
+	if err == nil {
+		err = errNoError
+	}
+	return ScriptJSONError{op, err}
+}
+
+func (e ScriptJSONError) Error() string {
+	return fmt.Sprintf("json.%s: %v", e.Op, e.Err)
+}
+
+func (e ScriptJSONError) Unwrap() error {
+	return e.Err
+}
+
 type ScriptLoadError struct {
 	Source string
 	Err    error

nix/package.nix

@@ -0,0 +1,44 @@
+{
+  lib,
+  buildGoModule,
+  go_1_27,
+  rev ? "unknown",
+  buildDate ? "unknown",
+}:
+
+(buildGoModule.override { go = go_1_27; }) (finalAttrs: {
+  pname = "sarin";
+  version = "1.4.4"; # bump per release
+
+  src = lib.cleanSource ../.;
+
+  vendorHash = "sha256-KUxzFDxYbKvKASMze+f7jxfpCQbs01ezeG6a1VboHxw=";
+
+  subPackages = [ "cmd/cli" ];
+
+  env.CGO_ENABLED = 0; # fully static binary
+
+  ldflags = [
+    "-s"
+    "-w"
+    "-X=go.aykhans.me/sarin/internal/version.Version=v${finalAttrs.version}"
+    "-X=go.aykhans.me/sarin/internal/version.GitCommit=${rev}"
+    "-X=go.aykhans.me/sarin/internal/version.BuildDate=${buildDate}"
+  ];
+
+  preBuild = ''
+    ldflags+=("-X 'go.aykhans.me/sarin/internal/version.GoVersion=$(go version)'")
+  '';
+
+  postInstall = ''
+    mv $out/bin/cli $out/bin/sarin
+  '';
+
+  meta = {
+    description = "High-performance HTTP load testing tool built with Go and fasthttp";
+    homepage = "https://github.com/aykhans/sarin";
+    license = lib.licenses.mit;
+    mainProgram = "sarin";
+    maintainers = [ ];
+  };
+})