feat: add import support to wasm playground editor by Mossaka · Pull Request #16440 · github/gh-aw

Mossaka · 2026-02-17T21:00:57Z

Summary

Introduces a virtual filesystem (virtual_fs.go / virtual_fs_wasm.go) so the wasm compiler can resolve imports: without real filesystem access
Replaces direct os.ReadFile calls in import/include processors with an overridable readFileFunc — native builds default to os.ReadFile, wasm builds use the virtual FS
Updates compileWorkflow(md, files?) to accept an optional files map for import resolution
Adds a file tab system to the playground editor: users can create shared imports (e.g. shared/tools.md), switch between tabs, and the compiler resolves them automatically

Test plan

GOOS=js GOARCH=wasm go build ./cmd/gh-aw-wasm succeeds
go build ./cmd/gh-aw still works (native build)
go test -short ./pkg/parser/ passes
go test -short ./pkg/workflow/ passes
Manual: open playground, add a shared import tab, reference it via imports:, verify compilation works

🤖 Generated with Claude Code

Enable `imports:` resolution in the browser-based wasm compiler by introducing a virtual filesystem. The editor now supports multiple file tabs — the main workflow file plus any shared imports — and passes them to the Go wasm runtime as a files map. Changes: - Add virtual_fs.go / virtual_fs_wasm.go for in-memory file storage - Replace os.ReadFile with readFileFunc in import/include/yaml parsers - Update remote_fetch_wasm.go to check virtual FS instead of os.Stat - Accept optional files object in compileWorkflow(md, files) - Thread files through compiler-worker.js and compiler-loader.js - Add file tab UI to the playground editor (add/remove/switch tabs) Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Copilot

Pull request overview

This PR adds import/include support to the WASM playground compiler by introducing a virtual filesystem for in-browser builds and wiring the editor/worker protocol to pass additional files for import resolution.

Changes:

Introduces a parser-level overridable readFileFunc, with a WASM virtual filesystem implementation (SetVirtualFiles / ClearVirtualFiles).
Updates include/import/YAML-import code paths to use readFileFunc instead of os.ReadFile.
Extends the WASM compiler bridge and playground editor to pass/maintain a files map (via file tabs) so imports: can resolve in the browser.

Reviewed changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
pkg/parser/yaml_import.go	Switch YAML import reads to `readFileFunc`.
pkg/parser/virtual_fs.go	Adds `readFileFunc` indirection (defaults to `os.ReadFile`).
pkg/parser/virtual_fs_wasm.go	Implements in-memory virtual FS + overrides `readFileFunc` for WASM.
pkg/parser/remote_fetch_wasm.go	Uses virtual FS existence checks for include resolution in WASM.
pkg/parser/include_processor.go	Reads included files via `readFileFunc`.
pkg/parser/include_expander.go	Reads included files via `readFileFunc`.
pkg/parser/import_processor.go	Reads imported files via `readFileFunc` (including topo-sort).
docs/public/wasm/compiler-worker.js	Extends worker protocol to forward optional `files`.
docs/public/wasm/compiler-loader.js	Extends `compile(markdown, files?)` API and message payload.
docs/public/editor/index.html	Adds tabbed file UI and passes non-main files as imports to the compiler.
cmd/gh-aw-wasm/main.go	Accepts optional `filesObject`, sets virtual FS, and compiles with import support.

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Copilot · 2026-02-17T21:06:22Z

cmd/gh-aw-wasm/main.go

+// jsObjectToFileMap converts a JS object {path: content, ...} to map[string][]byte.
+func jsObjectToFileMap(obj js.Value) map[string][]byte {
+	files := make(map[string][]byte)
+
+	// Use Object.keys() to iterate over the JS object
+	keys := js.Global().Get("Object").Call("keys", obj)
+	length := keys.Length()
+	for i := 0; i < length; i++ {
+		key := keys.Index(i).String()
+		value := obj.Get(key).String()
+		files[key] = []byte(value)
+	}
+
+	return files


jsObjectToFileMap assumes the optional second argument is a plain object whose values are strings. If a caller passes a non-object (e.g. a string/array) or non-string values, .String() will coerce silently (e.g. "[object Object]") and lead to confusing compile errors. Consider validating args[1] is an object and that each value is a string (or can be converted to one) and rejecting the Promise with a clear message when the shape is invalid.

Copilot · 2026-02-17T21:06:22Z

cmd/gh-aw-wasm/main.go

+	// Set up virtual filesystem for import resolution
+	if files != nil {
+		parser.SetVirtualFiles(files)
+		defer parser.ClearVirtualFiles()
+	}


SetVirtualFiles/ClearVirtualFiles mutate package-level globals, but compileWorkflow launches each request in a goroutine. If multiple compileWorkflow() calls are in-flight concurrently (possible for createWorkerCompiler().compile() consumers), the virtual FS can be overwritten/cleared mid-compilation, producing incorrect results. Consider serializing compilation in the WASM entrypoint (e.g., a mutex) or making the virtual FS state per-compilation instead of global.

Copilot · 2026-02-17T21:06:23Z

docs/public/editor/index.html

+    const tab = document.createElement('div');
+    tab.className = 'tab' + (file.name === activeTab ? ' active' : '');
+    tab.dataset.name = file.name;
+
+    const label = document.createElement('span');
+    label.textContent = file.name;
+    tab.appendChild(label);
+
+    // Close button (not for the main workflow file)
+    if (file.name !== MAIN_FILE) {
+      const close = document.createElement('button');
+      close.className = 'tab-close';
+      close.title = 'Remove file';
+      close.innerHTML = '<svg width="12" height="12" viewBox="0 0 16 16" fill="currentColor"><path d="M3.72 3.72a.75.75 0 011.06 0L8 6.94l3.22-3.22a.749.749 0 011.275.326.749.749 0 01-.215.734L9.06 8l3.22 3.22a.749.749 0 01-.326 1.275.749.749 0 01-.734-.215L8 9.06l-3.22 3.22a.751.751 0 01-1.042-.018.751.751 0 01-.018-1.042L6.94 8 3.72 4.78a.75.75 0 010-1.06z"/></svg>';
+      close.addEventListener('click', (e) => {
+        e.stopPropagation();
+        removeTab(file.name);
+      });
+      tab.appendChild(close);
+    }
+
+    tab.addEventListener('click', () => switchTab(file.name));
+    tabBar.insertBefore(tab, tabAdd);
+  }


Tabs are rendered as clickable <div> elements with click handlers, which are not keyboard-focusable by default and lack appropriate ARIA roles. This makes the new tab system hard to use with keyboard-only navigation and screen readers. Consider rendering tabs as <button> elements (or add role="tab", tabindex="0", and keyboard handlers for Enter/Space + focus management).

# Conflicts: # docs/public/editor/index.html

The schema versioning change (e995df1) requires lock files to have a gh-aw-metadata comment. Update the test lock content to include it. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

# Conflicts: # pkg/workflow/action_sha_validation_test.go

# Conflicts: # docs/public/editor/index.html

Copilot AI review requested due to automatic review settings February 17, 2026 21:00

Copilot started reviewing on behalf of Mossaka February 17, 2026 21:01 View session

Copilot AI reviewed Feb 17, 2026

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github-actions bot mentioned this pull request Feb 17, 2026

[Contribution Check Report]Contribution Check — February 17, 2026 #16442

Closed

Mossaka and others added 4 commits February 17, 2026 21:38

Merge remote-tracking branch 'origin/main' into feat/wasm-imports

8ea5de7

# Conflicts: # docs/public/editor/index.html

fix: add schema metadata to test lock content for compatibility

c8c7958

The schema versioning change (e995df1) requires lock files to have a gh-aw-metadata comment. Update the test lock content to include it. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Merge remote-tracking branch 'origin/main' into feat/wasm-imports

d4ab500

# Conflicts: # pkg/workflow/action_sha_validation_test.go

Merge remote-tracking branch 'origin/main' into feat/wasm-imports

e56e3e1

# Conflicts: # docs/public/editor/index.html

Mossaka merged commit bc7b473 into main Feb 17, 2026
54 checks passed

Mossaka deleted the feat/wasm-imports branch February 17, 2026 22:59

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feat: add import support to wasm playground editor#16440

feat: add import support to wasm playground editor#16440
Mossaka merged 5 commits intomainfrom
feat/wasm-imports

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Mossaka commented Feb 17, 2026

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