feat: compile gh-aw compiler to WebAssembly for browser usage by Mossaka · Pull Request #16289 · github/gh-aw

Mossaka · 2026-02-17T05:31:47Z

Summary

Adds GOOS=js GOARCH=wasm build target (make build-wasm) that compiles the gh-aw workflow compiler to run entirely in the browser
Uses Go build tags to swap TUI libraries and os/exec-dependent code with lightweight stubs
Provides a Promise-based JS API: compileWorkflow(markdown) → {yaml, warnings, error}
Includes an interactive playground (wasm-playground/) and a live editor docs page (/reference/live-editor/)
Wasm binary (~17MB) is gitignored and generated at deploy time via scripts/bundle-wasm-docs.sh

What's included

Area	Files	Description
Build tags	~20 existing files	`!js && !wasm` constraints on files using lipgloss, bubbletea, huh, os/exec, go-gh
Wasm stubs	~20 new `_wasm.go` files	Plain-text/no-op implementations for browser builds
String API	`compiler_string_api.go`	`ParseWorkflowString()` + `CompileToYAML()` for in-memory compilation
Entry point	`cmd/gh-aw-wasm/main.go`	Registers `compileWorkflow` global via `syscall/js`
JS library	`wasm-playground/lib/`, `docs/public/wasm/`	Browser loader, Web Worker wrapper
Playground	`wasm-playground/index.html`	Split-panel editor for testing
Docs	`reference/wasm-compilation.md`, `reference/live-editor.mdx`	Reference docs + live editor page

Test plan

GOOS=js GOARCH=wasm go build succeeds
Native go build ./cmd/gh-aw still works (no regressions)
Unit tests pass: pkg/tty, pkg/styles, pkg/console, pkg/workflow, pkg/parser
Playwright browser test: wasm loads, compiles sample workflow, produces valid YAML
make build-docs succeeds with new docs pages
Manual: open playground in browser, paste workflow markdown, verify YAML output

🤖 Generated with Claude Code

Add GOOS=js GOARCH=wasm build target that compiles the workflow compiler to run in the browser. Uses build tags to swap TUI libraries (lipgloss, bubbletea, huh) and os/exec-dependent validation with plain-text stubs. Key changes: - Build tags (!js && !wasm / js || wasm) on ~20 existing files - ~20 new _wasm.go stub files for platform-specific code - ParseWorkflowString() for in-memory compilation without filesystem - CompileToYAML() returns YAML as string without writing to disk - Promise-based JS API: compileWorkflow(markdown) → {yaml, warnings, error} - Web Worker loader for off-main-thread compilation - Interactive playground at wasm-playground/ - Live editor page in docs at /reference/live-editor/ - Documentation at /reference/wasm-compilation/ - make build-wasm target, scripts/bundle-wasm-docs.sh for deployment The wasm binary (~17MB) is gitignored and generated at deploy time via scripts/bundle-wasm-docs.sh. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Copilot

Pull request overview

Adds a WebAssembly build of the gh-aw workflow compiler for in-browser compilation, along with a playground and docs integration so users can compile markdown workflows to GitHub Actions YAML client-side.

Changes:

Introduces a build-wasm Makefile target and a cmd/gh-aw-wasm entrypoint exporting a JS-facing compileWorkflow() Promise API.
Adds extensive js/wasm build-tagged stubs to replace TUI, os/exec, and network-dependent functionality at compile time.
Adds a standalone playground plus an Astro docs “Live Editor” page backed by a Web Worker loader, and supporting docs/scripts/gitignore updates.

Reviewed changes

Copilot reviewed 59 out of 60 changed files in this pull request and generated 10 comments.

Show a summary per file

File	Description
wasm-playground/lib/gh-aw-compiler.js	JS glue to load wasm + expose `Compiler.compile()`
wasm-playground/index.html	Standalone browser playground UI + schema validation
scripts/bundle-wasm-docs.sh	Builds wasm and copies artifacts into docs public dir
pkg/workflow/repository_features_validation_wasm.go	Wasm stub for repo-features validation
pkg/workflow/repository_features_validation.go	Excludes native repo-features validation from wasm
pkg/workflow/pip_validation_wasm.go	Wasm stubs for pip/uv validation
pkg/workflow/pip_validation.go	Excludes native pip validation from wasm
pkg/workflow/npm_validation_wasm.go	Wasm stub for npm validation
pkg/workflow/npm_validation.go	Excludes native npm validation from wasm
pkg/workflow/github_cli_wasm.go	Wasm stub for gh CLI integration
pkg/workflow/github_cli.go	Excludes native gh CLI integration from wasm
pkg/workflow/git_helpers_wasm.go	Wasm stubs for git helpers
pkg/workflow/git_helpers.go	Excludes native git helpers from wasm
pkg/workflow/docker_validation_wasm.go	Wasm stub for docker image validation
pkg/workflow/docker_validation.go	Excludes native docker validation from wasm
pkg/workflow/dependabot_wasm.go	Wasm stub for dependabot generation
pkg/workflow/dependabot.go	Excludes native dependabot generation from wasm
pkg/workflow/compiler_types.go	Adds `contentOverride` to support in-memory compilation
pkg/workflow/compiler_string_api.go	Adds string-based parse/compile API (`ParseWorkflowString`, `CompileToYAML`)
pkg/workflow/compiler_orchestrator_tools.go	Uses content-based name extraction when compiling from memory
pkg/tty/tty_wasm.go	Wasm stub for TTY detection
pkg/tty/tty.go	Excludes native TTY detection from wasm
pkg/styles/theme_wasm.go	Wasm no-op styles (no ANSI)
pkg/styles/theme_test.go	Excludes style tests from wasm
pkg/styles/theme.go	Excludes native theme from wasm
pkg/parser/remote_fetch_wasm.go	Wasm behavior for include/import resolution (no remote fetch)
pkg/parser/remote_fetch.go	Excludes native remote fetch from wasm
pkg/parser/github_wasm.go	Wasm token lookup via env vars only
pkg/parser/github.go	Excludes native token retrieval from wasm
pkg/parser/frontmatter_content.go	Adds content-based workflow-name extraction helper
pkg/console/spinner_wasm.go	Wasm spinner stub
pkg/console/spinner.go	Excludes native spinner from wasm
pkg/console/select_wasm.go	Wasm select prompt stub
pkg/console/select.go	Excludes native select prompt from wasm; removes duplicated types
pkg/console/progress_wasm.go	Wasm progress bar stub
pkg/console/progress_shared.go	Shared `formatBytes()` helper extracted from native progress
pkg/console/progress.go	Excludes native progress UI from wasm; removes duplicated helper
pkg/console/list_wasm.go	Wasm interactive list stub
pkg/console/list.go	Excludes native interactive list from wasm; removes duplicated types
pkg/console/layout_wasm.go	Wasm layout helpers (plain text)
pkg/console/layout.go	Excludes native layout helpers from wasm
pkg/console/input_wasm.go	Wasm input prompt stubs
pkg/console/input.go	Excludes native input prompts from wasm
pkg/console/form_wasm.go	Wasm form stub
pkg/console/form.go	Excludes native forms from wasm; removes duplicated types
pkg/console/console_wasm.go	Wasm console formatting (plain text)
pkg/console/console_types.go	Consolidates shared console types/helpers across builds
pkg/console/console.go	Excludes native styled console from wasm; moves shared types out
pkg/console/confirm_wasm.go	Wasm confirm prompt stub
pkg/console/confirm.go	Excludes native confirm prompt from wasm
pkg/console/banner_wasm.go	Wasm banner stub
pkg/console/banner.go	Excludes native banner from wasm
docs/src/content/docs/reference/wasm-compilation.md	Reference documentation for wasm build + JS API
docs/src/content/docs/reference/live-editor.mdx	Live editor docs page embedding worker-backed compiler
docs/public/wasm/compiler-worker.js	Web Worker that loads wasm and exposes compile via messages
docs/public/wasm/compiler-loader.js	ES module wrapper for worker protocol + `ready` promise
docs/astro.config.mjs	Adds “Live Editor” to reference navigation
cmd/gh-aw-wasm/main.go	Wasm entrypoint that registers global `compileWorkflow`
Makefile	Adds `build-wasm` target
.gitignore	Ignores wasm artifacts and docs wasm outputs

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Copilot · 2026-02-17T05:38:33Z

pkg/workflow/github_cli_wasm.go

+import (
+	"bytes"
+	"context"
+	"fmt"
+	"os/exec"
+)


pkg/workflow/github_cli_wasm.go is built for js/wasm but imports and references os/exec (*exec.Cmd, exec.Command). os/exec is not available on GOOS=js builds, so this stub will fail to compile for the Wasm target. Consider removing this file entirely for Wasm builds (if nothing needs these functions), or refactor the ExecGH* API so the Wasm build doesn’t depend on *exec.Cmd/os/exec types.

Copilot · 2026-02-17T05:38:33Z

wasm-playground/index.html

The playground loads js-yaml and ajv from a third-party CDN without Subresource Integrity (SRI) and without pinning via local bundling. For a docs/playground surface, this increases supply-chain risk. Prefer bundling these dependencies (or serving from your own static assets) and/or adding SRI + crossorigin attributes.

Copilot · 2026-02-17T05:38:33Z

wasm-playground/lib/gh-aw-compiler.js

Compiler.compile(markdown, importResolver) forwards importResolver to the global compileWorkflow, but the current Wasm entrypoint (cmd/gh-aw-wasm/main.go) only reads args[0] and ignores any resolver callback. Either implement the resolver plumbing end-to-end (Go -> JS callback) or remove/document that the second argument is unsupported to avoid a confusing no-op API.

Copilot · 2026-02-17T05:38:34Z

wasm-playground/lib/gh-aw-compiler.js

WebAssembly.instantiateStreaming(fetch(...)) will fail in common setups where the server doesn’t serve .wasm with application/wasm (or when using file://). Consider adding a fallback to fetch(...).then(r => r.arrayBuffer()).then(buf => WebAssembly.instantiate(buf, ...)) so the playground/docs loader works more reliably.

Copilot · 2026-02-17T05:38:34Z

cmd/gh-aw-wasm/main.go

+// Usage: compileWorkflow(markdownString) → Promise<{yaml, warnings, error}>
+func compileWorkflow(this js.Value, args []js.Value) any {
+	if len(args) < 1 {
+		return newRejectedPromise("compileWorkflow requires at least 1 argument: markdown string")
+	}
+


This JS API/docs describe compileWorkflow(markdown, importResolver?), but the current implementation only uses args[0] and ignores a resolver callback. If import resolution is intended to work in-browser, the Go entrypoint needs to accept/call the JS resolver (and the compiler needs a way to consume that content). Otherwise, update the public API contract (JS glue + docs) to avoid promising unsupported behavior.

Suggested change

// Usage: compileWorkflow(markdownString) → Promise<{yaml, warnings, error}>

func compileWorkflow(this js.Value, args []js.Value) any {

if len(args) < 1 {

return newRejectedPromise("compileWorkflow requires at least 1 argument: markdown string")

}

// Usage (WASM): compileWorkflow(markdownString) → Promise<{yaml, warnings, error}>

// Note: An importResolver callback is not supported in this WASM entrypoint; passing a

// second argument will cause the returned Promise to be rejected.

func compileWorkflow(this js.Value, args []js.Value) any {

if len(args) < 1 {

return newRejectedPromise("compileWorkflow requires at least 1 argument: markdown string")

}

// If a second argument is provided (e.g., an importResolver callback), explicitly

// reject the call to avoid silently ignoring unsupported behavior.

if len(args) > 1 && args[1].Type() != js.TypeUndefined && args[1].Type() != js.TypeNull {

return newRejectedPromise("compileWorkflow (WASM) does not support an importResolver argument; omit the second parameter")

}

Copilot · 2026-02-17T05:38:34Z

cmd/gh-aw-wasm/main.go

Each call to compileWorkflow() allocates a new js.Func (handler := js.FuncOf(...)) but never calls Release(). In long-lived Wasm sessions (live editor / playground), this leaks JS function wrappers over time. Ensure the handler is released after resolve/reject (or use a reusable handler) to avoid unbounded growth.

Copilot · 2026-02-17T05:38:35Z

docs/src/content/docs/reference/wasm-compilation.md

The docs state Go "1.23 or later", but go.mod specifies go 1.25.0. Update the prerequisite to match the repo’s actual minimum Go version so readers don’t attempt a build with an unsupported toolchain.

Suggested change

- Go 1.23 or later

- Go 1.25 or later

Copilot · 2026-02-17T05:38:35Z

wasm-playground/index.html

showValidation() builds div.innerHTML and injects item.path without escaping. Since item.path ultimately derives from user-controlled YAML (schema validation errors include instancePath), this can lead to XSS in the playground. Use textContent for both path/message, or escape item.path before injecting into innerHTML.

Copilot · 2026-02-17T05:38:35Z

docs/src/content/docs/reference/wasm-compilation.md

This page documents compileWorkflow(markdown, importResolver?) and claims the compiler will call the resolver for imports:. The current Wasm entrypoint does not accept a resolver argument (and wasm-playground/lib/gh-aw-compiler.js passes one that will be ignored). Please align the docs with the implemented API, or add the missing resolver support end-to-end.

Copilot · 2026-02-17T05:38:35Z

pkg/workflow/compiler_string_api.go

+// CompileToYAML compiles workflow data and returns the YAML as a string
+// without writing to disk. This is useful for Wasm builds and programmatic usage.
+func (c *Compiler) CompileToYAML(workflowData *WorkflowData, markdownPath string) (string, error) {
+	c.markdownPath = markdownPath
+
+	startTime := time.Now()
+	defer func() {
+		log.Printf("CompileToYAML completed in %v", time.Since(startTime))
+	}()
+
+	c.stepOrderTracker = NewStepOrderTracker()
+	c.scheduleFriendlyFormats = nil
+
+	if c.artifactManager == nil {
+		c.artifactManager = NewArtifactManager()
+	} else {
+		c.artifactManager.Reset()
+	}
+
+	lockFile := stringutil.MarkdownToLockFile(markdownPath)
+
+	if err := c.validateWorkflowData(workflowData, markdownPath); err != nil {
+		return "", err
+	}
+
+	yamlContent, err := c.generateAndValidateYAML(workflowData, markdownPath, lockFile)
+	if err != nil {
+		return "", err
+	}
+
+	return yamlContent, nil
+}
+
+// ParseWorkflowString parses workflow markdown content from a string rather than a file.
+// This is the primary entry point for Wasm/browser usage where filesystem access is unavailable.
+// The virtualPath is used for error messages and lock file naming (e.g., "workflow.md").
+func (c *Compiler) ParseWorkflowString(content string, virtualPath string) (*WorkflowData, error) {
+	log.Printf("ParseWorkflowString: parsing %d bytes with virtual path %s", len(content), virtualPath)


ParseWorkflowString() / CompileToYAML() introduce a new public string-based compilation path, but there are currently no unit tests exercising it (including error formatting, virtual path behavior, and ensuring WithNoEmit(true) doesn’t write lock files). Given the surrounding package has extensive tests, adding a focused test would help prevent regressions in the browser build.

- Fix live editor compilation error by updating compiler-worker.js path - Fix light mode styling with Starlight CSS custom properties - Add wasm-opt -Oz optimization to build-wasm target (~8% size reduction) - Fix wasm_exec.js path resolution in bundle script for Go 1.24+ - Add .gitignore entries for wasm build artifacts Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

PR review fixes: - Reject unsupported importResolver arg in wasm entrypoint - Fix js.Func leak by releasing handlers after resolve/reject - Add SRI hashes for CDN scripts (js-yaml, ajv) - Fix XSS in validation display (innerHTML → textContent) - Add WebAssembly.instantiate fallback for non-streaming loads - Remove importResolver from JS API (not yet supported) - Fix Go version prerequisite (1.23 → 1.25) - Add unit tests for ParseWorkflowString/CompileToYAML - Document os/exec availability in js/wasm build New standalone editor: - Full-screen editor at /editor/ with dark/light theme toggle - Split-panel layout with line numbers and auto-compile - Works independently of Starlight layout Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

- Replace errors.As with assert.ErrorAs (testifylint) - Remove unused errors import Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

- Fix XSS: use textContent instead of innerHTML for error messages (live-editor.mdx) - Add WebAssembly.instantiate fallback in compiler-worker.js - Fix Makefile portability: replace stat -c%s with wc -c (works on macOS) - Remove unused escapeHtml function from playground - Fix docs contradiction about import resolver support Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

The standalone playground was a development/testing tool used to verify the wasm compiler works in the browser. It's now replaced by the production editor at docs/public/editor/index.html. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Copilot AI review requested due to automatic review settings February 17, 2026 05:31

Copilot started reviewing on behalf of Mossaka February 17, 2026 05:32 View session

Copilot AI reviewed Feb 17, 2026

View reviewed changes

Mossaka and others added 4 commits February 17, 2026 05:55

fix: lint errors in compiler_string_api_test.go

23b23bd

- Replace errors.As with assert.ErrorAs (testifylint) - Remove unused errors import Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

fix: go fmt formatting issues

2b954f8

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

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Mossaka and others added 2 commits February 17, 2026 06:41

Mossaka merged commit 1a3cd12 into main Feb 17, 2026
52 checks passed

Mossaka deleted the feat/wasm-compiler branch February 17, 2026 06:57

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Mossaka commented Feb 17, 2026

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