fix(firefox): add buffered stdin fallback

README.md

@@ -219,6 +219,8 @@ Firefox desktop is also a supported release target, but its support contract is
 different:
 
 - compile/run, Monaco, and extension-runtime flows are supported
+- programs that read `std::cin` use pre-supplied buffered stdin (up to 256 KiB);
+  live prompt-by-prompt stdin remains available on Chromium-family builds
 - file open/save and folder import use fallback browser flows rather than
   Chromium File System Access APIs
 - persistent folder write-back and directory-handle session restore may be
@@ -232,7 +234,7 @@ Full parity requires:
 - File System Access APIs (`showOpenFilePicker`, `showDirectoryPicker`,
   `showSaveFilePicker`)
 - Web Workers and WebAssembly
-- `SharedArrayBuffer` and `Atomics.waitAsync` for interactive stdin
+- `SharedArrayBuffer` and `Atomics.waitAsync` for Chromium live interactive stdin
 - Managed browser policies that allow local file read/write prompts
 
 ### Release-blocking checks
@@ -459,8 +461,8 @@ manual/GitHub-distributed channel.
 4. For self-distribution, verify that the protected release workflow produced a
    signed artifact under `release/firefox-unlisted/`.
 5. Install the signed XPI in Firefox and complete the manual QA checklist
-   below, paying special attention to the documented workspace-persistence
-   limitations.
+   in `docs/firefox-stdin-runtime-acceptance.md`, paying special attention to
+   buffered stdin and the documented workspace-persistence limitations.
 
 ### Manual release QA checklist
 
@@ -524,7 +526,9 @@ Copy the resulting `clang.js` and `clang.wasm` into `dist/clang/`.
   script" dialog.  The compiler runs in a dedicated Web Worker to avoid blocking
   the UI.
 - **Browser scope**: Full parity targets desktop Chrome, Edge, Brave, and
-  Chromium. Firefox and Safari are outside the current release target.
+  Chromium. Firefox is a compatible release target with buffered stdin and
+  workspace-persistence limitations; Safari is outside the current release
+  target.
 - **Managed browsers**: Enterprise policies that block File System Access prompts
   prevent full local workspace read/write support.
 

docs/firefox-stdin-runtime-acceptance.md

@@ -0,0 +1,88 @@
+# Firefox buffered stdin runtime acceptance
+
+Use this procedure to prove GitHub issue #53 is fixed in a real Firefox
+extension context. `npm run test:browser:firefox` validates packaging and
+manifest compatibility, but it does not execute a compiled program in Firefox.
+
+## Setup
+
+1. Run:
+
+   ```bash
+   npm run build
+   npm run test:browser:firefox
+   ```
+
+2. Open `about:debugging#/runtime/this-firefox` in Firefox.
+3. Choose **Load Temporary Add-on** and select `dist-firefox/manifest.json`.
+   For release validation, repeat with the signed XPI under
+   `release/firefox-unlisted/`.
+4. Open browser.cpp from the extension toolbar action.
+
+Record the Firefox version and the unpacked directory or signed XPI path used.
+
+## Test program
+
+Replace the editor contents with exactly:
+
+```cpp
+#include <iostream>
+#include <string>
+
+int main() {
+    std::string name;
+    int age = 0;
+
+    std::cout << "Name? ";
+    std::cin >> name;
+    std::cout << "Age? ";
+    std::cin >> age;
+
+    if (!std::cin) {
+        std::cerr << "input failed\n";
+        return 2;
+    }
+
+    std::cout << "\nHello " << name << ", next year " << (age + 1) << "\n";
+    return 0;
+}
+```
+
+Choose **Compile and Run**. In the **Pre-supplied stdin** dialog, enter exactly:
+
+```text
+Ada
+41
+```
+
+Keep the final newline after `41`, then choose **Run program**.
+
+## Expected result
+
+The process exits with code `0`, stderr is empty, and stdout is exactly:
+
+```text
+Name? Age?␠
+Hello Ada, next year 42
+```
+
+The `␠` marker represents the single trailing ASCII space emitted after
+`Age?`.
+
+The terminal and browser console must not contain any of these strings:
+
+```text
+Interactive stdin requires SharedArrayBuffer
+Cross-Origin-Opener-Policy
+Cross-Origin-Embedder-Policy
+```
+
+## PR evidence
+
+Paste the following into the pull request:
+
+- Firefox version
+- tested artifact path
+- observed stdout
+- confirmation that stderr was empty
+- confirmation that none of the old SharedArrayBuffer/COOP/COEP errors appeared

docs/release-playbook.md

@@ -87,7 +87,8 @@ real Firefox desktop build:
 2. Confirm Monaco renders and the default sample appears without blocking
    console/runtime errors.
 3. Compile and run the default sample program.
-4. Run a program that reads stdin and confirm terminal interaction works.
+4. Complete `docs/firefox-stdin-runtime-acceptance.md` and confirm pre-supplied
+   buffered stdin works without the old SharedArrayBuffer/COOP/COEP error.
 5. Open a local source file with Firefox's fallback picker and save changes.
 6. Import a folder, compile a multi-file project, and confirm diagnostics appear
    in the expected file.

manifest.json

@@ -3,7 +3,7 @@
   "name": "browser.cpp",
   "short_name": "browser.cpp",
   "description": "In-browser C++20 IDE powered by Monaco Editor and WASM Clang",
-  "version": "0.3.2",
+  "version": "0.4.0",
   "minimum_chrome_version": "105",
   "icons": {
     "16": "icons/icon16.png",

package.json

@@ -1,6 +1,6 @@
 {
   "name": "browser.cpp",
-  "version": "0.3.2",
+  "version": "0.4.0",
   "description": "In-browser C++20 IDE with WASM Clang toolchain",
   "private": true,
   "scripts": {
@@ -10,7 +10,7 @@
     "lint": "eslint .",
     "build": "npm run build:webpack && npm run build:targets",
     "build:firefox": "npm run build",
-    "test:e2e": "node --experimental-detect-module --test scripts/e2e-session-persistence.test.mjs scripts/e2e-session-restore-choice.test.mjs scripts/e2e-multifile-build.test.mjs scripts/e2e-workspace-file-tracking.test.mjs scripts/e2e-terminal-mkdir.test.mjs scripts/e2e-terminal-stop.test.mjs scripts/e2e-terminal-git-removal.test.mjs scripts/e2e-terminal-stop-icon.test.mjs scripts/e2e-browser-compatibility.test.mjs scripts/e2e-firefox-compatibility.test.mjs scripts/e2e-wasi-shim.test.mjs scripts/e2e-release-packaging.test.mjs",
+    "test:e2e": "node --experimental-detect-module --test scripts/e2e-session-persistence.test.mjs scripts/e2e-session-restore-choice.test.mjs scripts/e2e-multifile-build.test.mjs scripts/e2e-workspace-file-tracking.test.mjs scripts/e2e-terminal-mkdir.test.mjs scripts/e2e-terminal-stop.test.mjs scripts/e2e-terminal-git-removal.test.mjs scripts/e2e-terminal-stop-icon.test.mjs scripts/e2e-buffered-stdin-ui.test.mjs scripts/e2e-browser-compatibility.test.mjs scripts/e2e-firefox-compatibility.test.mjs scripts/e2e-wasi-shim.test.mjs scripts/e2e-run-request.test.mjs scripts/e2e-release-packaging.test.mjs",
     "test:preflight-clang": "node scripts/preflight-clang-artifacts.js",
     "test:browser:chrome": "npm run test:preflight-clang && node scripts/smoke-browser.mjs chrome",
     "test:browser:edge": "npm run test:preflight-clang && node scripts/smoke-browser.mjs edge",

scripts/build-target-manifest.js

@@ -42,6 +42,8 @@ function createChromiumManifest(baseManifest) {
 function createFirefoxManifest(baseManifest, firefoxOverlay) {
   const manifest = mergeObjects(baseManifest, firefoxOverlay);
   delete manifest.minimum_chrome_version;
+  delete manifest.cross_origin_opener_policy;
+  delete manifest.cross_origin_embedder_policy;
   manifest.background = {
     scripts: ['firefox-background.js'],
   };

scripts/e2e-browser-compatibility.test.mjs

@@ -46,6 +46,8 @@ test('e2e: reports full Chromium-family capability support', () => {
   assert.deepEqual(report.limitations, []);
   assert.equal(report.capabilities.directoryPicker, true);
   assert.equal(report.capabilities.sharedArrayBuffer, true);
+  assert.equal(report.capabilities.interactiveStdin, true);
+  assert.equal(report.capabilities.stdinMode, 'interactive');
 });
 
 test('e2e: reports missing full-parity browser APIs', () => {

scripts/e2e-buffered-stdin-ui.test.mjs

@@ -0,0 +1,25 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+import { readFile } from 'node:fs/promises';
+
+test('e2e: buffered stdin dialog has accessible controls and status feedback', async () => {
+  const html = await readFile('src/ui/index.html', 'utf8');
+  const dialog = html.match(/<dialog id="buffered-stdin-dialog"[\s\S]*?<\/dialog>/)?.[0];
+
+  assert.ok(dialog, 'buffered stdin dialog markup should exist');
+  assert.match(dialog, /aria-labelledby="buffered-stdin-title"/);
+  assert.match(dialog, /<label for="buffered-stdin-input"/);
+  assert.match(dialog, /<textarea[\s\S]*id="buffered-stdin-input"[\s\S]*aria-describedby="buffered-stdin-feedback"/);
+  assert.match(dialog, /<textarea[\s\S]*maxlength="262144"/);
+  assert.match(dialog, /id="buffered-stdin-feedback"[\s\S]*aria-live="polite"/);
+  assert.match(dialog, /<button[^>]*id="buffered-stdin-cancel"/);
+  assert.match(dialog, /<button[^>]*id="buffered-stdin-run"/);
+});
+
+test('e2e: buffered stdin dialog styles remain usable in narrow extension windows', async () => {
+  const css = await readFile('src/ui/styles.css', 'utf8');
+
+  assert.match(css, /#buffered-stdin-dialog\s*\{[\s\S]*width:\s*min\(/);
+  assert.match(css, /#buffered-stdin-input\s*\{[\s\S]*resize:\s*vertical/);
+  assert.match(css, /buffered-stdin-feedback/);
+});

scripts/e2e-firefox-compatibility.test.mjs

@@ -35,9 +35,9 @@ function firefoxLikeRoot(overrides = {}) {
     },
     Worker() {},
     WebAssembly: { instantiate() {} },
-    SharedArrayBuffer() {},
-    Atomics: { waitAsync() {} },
-    crossOriginIsolated: true,
+    SharedArrayBuffer: undefined,
+    Atomics: {},
+    crossOriginIsolated: false,
     ...overrides,
   };
 }
@@ -54,8 +54,12 @@ test('e2e: Firefox compatibility report accepts supported fallback-based capabil
   assert.equal(report.ok, true);
   assert.equal(report.capabilities.browserFamily, 'firefox');
   assert.equal(report.capabilities.supportLevel, 'compatible');
+  assert.equal(report.capabilities.interactiveStdin, false);
+  assert.equal(report.capabilities.stdinMode, 'buffered');
   assert.deepEqual(report.missing, []);
+  assert.ok(report.limitations.some((item) => item.key === 'limitedInteractiveStdin'));
   assert.ok(report.limitations.some((item) => item.key === 'firefoxWorkspacePersistence'));
+  assert.ok(message.includes('pre-supplied buffered stdin'));
   assert.ok(message.includes('Persistent folder write-back'));
 });
 
@@ -70,6 +74,8 @@ test('e2e: target manifest generation creates a Firefox manifest without Chromiu
       service_worker: 'service-worker.js',
       type: 'module',
     },
+    cross_origin_opener_policy: { value: 'same-origin' },
+    cross_origin_embedder_policy: { value: 'require-corp' },
   });
   writeJson(path.join(repoRoot, 'manifest.firefox.json'), {
     browser_specific_settings: {
@@ -92,6 +98,16 @@ test('e2e: target manifest generation creates a Firefox manifest without Chromiu
 
   assert.equal(firefoxManifest.minimum_chrome_version, undefined);
   assert.equal(firefoxManifest.background.service_worker, undefined);
+  assert.equal(firefoxManifest.cross_origin_opener_policy, undefined);
+  assert.equal(firefoxManifest.cross_origin_embedder_policy, undefined);
+  assert.deepEqual(
+    result.chromiumManifest.cross_origin_opener_policy,
+    { value: 'same-origin' }
+  );
+  assert.deepEqual(
+    result.chromiumManifest.cross_origin_embedder_policy,
+    { value: 'require-corp' }
+  );
   assert.deepEqual(firefoxManifest.background.scripts, ['firefox-background.js']);
   assert.equal(firefoxManifest.browser_specific_settings.gecko.id, 'browser.cpp@example.test');
 });
@@ -105,6 +121,8 @@ test('e2e: createFirefoxManifest strips Chromium-specific background configurati
         type: 'module',
       },
       minimum_chrome_version: '105',
+      cross_origin_opener_policy: { value: 'same-origin' },
+      cross_origin_embedder_policy: { value: 'require-corp' },
     },
     {
       browser_specific_settings: {
@@ -117,5 +135,7 @@ test('e2e: createFirefoxManifest strips Chromium-specific background configurati
 
   assert.equal(manifest.minimum_chrome_version, undefined);
   assert.equal(manifest.background.service_worker, undefined);
+  assert.equal(manifest.cross_origin_opener_policy, undefined);
+  assert.equal(manifest.cross_origin_embedder_policy, undefined);
   assert.deepEqual(manifest.background.scripts, ['firefox-background.js']);
 });

scripts/e2e-run-request.test.mjs

@@ -0,0 +1,81 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+
+import {
+  BUFFERED_STDIN_MAX_BYTES,
+  validateRunRequest,
+} from '../src/workers/run-request.mjs';
+
+function interactiveRequest(overrides = {}) {
+  return {
+    type: 'run',
+    stdinMode: 'interactive',
+    sharedBuffer: new SharedArrayBuffer(16),
+    vfsFiles: [{ path: 'input.txt', bytes: new Uint8Array([1, 2]) }],
+    binaryBytes: new Uint8Array([0, 97, 115, 109]),
+    ...overrides,
+  };
+}
+
+test('e2e: worker run contract accepts and normalizes all stdin modes', () => {
+  const interactive = validateRunRequest(interactiveRequest());
+  assert.equal(interactive.ok, true);
+  assert.equal(interactive.value.stdin.mode, 'interactive');
+
+  const buffered = validateRunRequest(interactiveRequest({
+    stdinMode: 'buffered',
+    sharedBuffer: undefined,
+    stdinBuffer: new TextEncoder().encode('Ada\n41\n').buffer,
+  }));
+  assert.equal(buffered.ok, true);
+  assert.equal(buffered.value.stdin.mode, 'buffered');
+  assert.deepEqual(
+    [...buffered.value.stdin.bytes],
+    [...new TextEncoder().encode('Ada\n41\n')]
+  );
+
+  const none = validateRunRequest(interactiveRequest({
+    stdinMode: 'none',
+    sharedBuffer: undefined,
+  }));
+  assert.equal(none.ok, true);
+  assert.deepEqual(none.value.stdin, { mode: 'none' });
+});
+
+test('e2e: worker run contract rejects mismatched stdin variants', () => {
+  const cases = [
+    interactiveRequest({ sharedBuffer: new ArrayBuffer(16) }),
+    interactiveRequest({ stdinMode: 'buffered', sharedBuffer: undefined, stdinBuffer: 'Ada' }),
+    interactiveRequest({ stdinMode: 'none', sharedBuffer: new SharedArrayBuffer(16) }),
+    interactiveRequest({ stdinMode: 'unknown' }),
+  ];
+
+  for (const request of cases) {
+    const result = validateRunRequest(request);
+    assert.equal(result.ok, false);
+    assert.match(result.error, /stdin/i);
+  }
+});
+
+test('e2e: worker run contract rejects buffered stdin above the shared size limit', () => {
+  const result = validateRunRequest(interactiveRequest({
+    stdinMode: 'buffered',
+    sharedBuffer: undefined,
+    stdinBuffer: new Uint8Array(BUFFERED_STDIN_MAX_BYTES + 1),
+  }));
+
+  assert.equal(result.ok, false);
+  assert.match(result.error, /256 KiB/);
+});
+
+test('e2e: worker run contract rejects invalid binary and VFS byte fields', () => {
+  const invalidBinary = validateRunRequest(interactiveRequest({ binaryBytes: 'wasm' }));
+  assert.equal(invalidBinary.ok, false);
+  assert.match(invalidBinary.error, /binaryBytes/);
+
+  const invalidVfs = validateRunRequest(interactiveRequest({
+    vfsFiles: [{ path: 'input.txt', bytes: [1, 2] }],
+  }));
+  assert.equal(invalidVfs.ok, false);
+  assert.match(invalidVfs.error, /vfsFiles/);
+});