fix(browse): BROWSER.md says plainly how to enable WebGL; the mismatch refusal links Daemon discipline (#3030)

The GSTACK_DISABLE_GPU row now states the effect and the switch: set
GSTACK_DISABLE_GPU=off to enable WebGL (off is the only recognized value).
The reworded config-mismatch refusal links BROWSER.md's Daemon discipline
section. Free tests pin both.

Co-authored-by: Hagetino <Hagetino@users.noreply.github.com>

BROWSER.md

@@ -1606,7 +1606,7 @@ the global `~/.gstack/browser-skills/foo/` only inside project-a.
 | `BROWSE_TUNNEL` | 0 | Activate the dual-listener tunnel architecture (requires `NGROK_AUTHTOKEN`) |
 | `BROWSE_TUNNEL_LOCAL_ONLY` | 0 | Test-only — bind both listeners locally without ngrok |
 | `CHROMIUM_PROFILE` | unset | Explicit headed Chromium profile directory (used by gbrowser's gbd per-workspace); honored by headed launch and profile-lock cleanup, not used by headless sessions |
-| `GSTACK_DISABLE_GPU` | unset | Set to `off` to skip the macOS headless GPU-taming flag set (applied by default on Darwin to stop runaway GPU-process spin). That flag set also disables WebGL: `getContext('webgl')`/`'webgl2'` return `null`, so WebGL pages (three.js, Mapbox GL, sigma.js) show their fallback. Set `off` to QA WebGL or canvas-heavy apps. |
+| `GSTACK_DISABLE_GPU` | unset | On macOS, headless Chromium starts with a GPU-taming flag set (it stops runaway GPU-process spin) that also disables WebGL: `getContext('webgl')`/`'webgl2'` return `null`, so WebGL pages (three.js, Mapbox GL, sigma.js) show their fallback. Set `GSTACK_DISABLE_GPU=off` to enable WebGL (`off` is the only recognized value). |
 | `GSTACK_BROWSE_MAX_HTML_BYTES` | 52428800 (50MB) | `load-html` size cap |
 | `GSTACK_SECURITY_OFF` | unset | Emergency kill switch — disable ML classifier |
 | `GSTACK_STEALTH` | unset | Set to `extended` (also accepts `1`/`true`) to layer six aggressive patches (WebGL spoof, faked plugins, mediaDevices) on top of Layer C. Actively lies; can break sites. |

browse/src/cli.ts

@@ -860,6 +860,7 @@ async function ensureServer(flags?: GlobalFlags): Promise<ServerState> {
       } else {
         console.error(`[browse] a browse daemon for this project is running with --headed/--proxy (started by another session).`);
         console.error(`[browse] pass the same flags to use it, or run 'browse disconnect' to start a plain one.`);
+        console.error(`[browse] why: BROWSER.md, "Daemon discipline": https://github.com/garrytan/gstack/blob/main/BROWSER.md#headed-mode--proxy--browser-native-downloads-v12800`);
       }
       process.exit(1);
     }

browse/test/cli-config-mismatch-message.test.ts

@@ -43,6 +43,7 @@ describe('#3030: config-mismatch refusal names who started the daemon', () => {
     expect(r.out).toContain('running with --headed/--proxy (started by another session)');
     expect(r.out).toContain("pass the same flags to use it, or run 'browse disconnect'");
     expect(r.out).not.toContain('to apply --proxy/--headed');
+    expect(r.out).toContain('BROWSER.md, "Daemon discipline": https://github.com/garrytan/gstack/blob/main/BROWSER.md#headed-mode--proxy--browser-native-downloads-v12800');
   }, 45_000);
 
   test('a call that passed a different flag keeps the apply-via-disconnect hint', async () => {
@@ -51,3 +52,21 @@ describe('#3030: config-mismatch refusal names who started the daemon', () => {
     expect(r.out).toContain("run 'browse disconnect' first to apply --proxy/--headed");
   }, 45_000);
 });
+
+describe('#3030: BROWSER.md says how to enable WebGL', () => {
+  const browserMd = fs.readFileSync(path.resolve(import.meta.dir, '../../BROWSER.md'), 'utf8');
+
+  test('the GSTACK_DISABLE_GPU row states the effect and the only recognized value', () => {
+    const row = browserMd.split('\n').find(line => line.startsWith('| `GSTACK_DISABLE_GPU`')) ?? '';
+    expect(row).toContain('also disables WebGL');
+    expect(row).toContain('Set `GSTACK_DISABLE_GPU=off` to enable WebGL (`off` is the only recognized value).');
+  });
+
+  test('the Daemon discipline paragraph sits under the heading the refusal links to', () => {
+    const heading = browserMd.indexOf('### Headed mode + proxy + browser-native downloads (v1.28.0.0)');
+    const discipline = browserMd.indexOf('**Daemon discipline.**');
+    expect(heading).toBeGreaterThan(-1);
+    expect(discipline).toBeGreaterThan(heading);
+    expect(browserMd.slice(heading + 3, discipline).replace(/```[\s\S]*?```/g, '')).not.toMatch(/\n#{1,3} /);
+  });
+});