windows smoke: foreign-page mic check on a local origin, navigation verified

The example.com check could pass vacuously if the runner can't reach the
internet (goto failed silently, the mic request then came from the app's
own page). Serve a page on http://localhost:9333 instead, confirm the
navigation happened, and fail on builds that should refuse it.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPmy3tPq869XDW4njjVaKA

.gitea/workflows/windows-smoke.yml

@@ -0,0 +1,136 @@
+# cinny-desktop #19: smoke-test the Windows app on the `windows` runner.
+#
+# Installs the NSIS bundle silently, starts the installed app with WebView2's
+# DevTools port open, and drives its real page with scripts/windows-smoke.mjs
+# (playwright-core over CDP): boots to the login screen, local server address,
+# microphone permission for the app and not for a foreign page, the call page's
+# own origin + isolation, the Credential Manager round trip. Features a build
+# doesn't have are reported "n/a".
+#
+# Run it from the Actions tab (workflow_dispatch):
+# - no `ref`: tests the published nightly installer (a couple of minutes);
+# - `ref` = a branch (e.g. a PR branch): builds that branch, then tests it.
+name: Windows smoke
+
+on:
+  workflow_dispatch:
+    inputs:
+      ref:
+        description: 'Branch to build and test (empty: test the published nightly)'
+        required: false
+        default: ''
+
+env:
+  GITEA_URL: ${{ github.server_url }}
+  REPO: ${{ github.repository }}
+
+jobs:
+  smoke:
+    runs-on: windows
+    timeout-minutes: 90
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-node@v4
+        with:
+          node-version-file: .node-version
+
+      - name: Download the published nightly installer
+        if: ${{ inputs.ref == '' }}
+        shell: powershell
+        run: |
+          New-Item -ItemType Directory -Force -Path smoke-installer | Out-Null
+          Invoke-WebRequest -Uri "$env:GITEA_URL/$env:REPO/releases/download/latest/LotusChat-x86_64-setup.exe" -OutFile smoke-installer\setup.exe
+          Get-Item smoke-installer\setup.exe | Select-Object Name, Length
+
+      # A second actions/checkout in one job trips over the host runner's
+      # action cache on Windows ("Access is denied" on its pack files), so
+      # fetch the branch into a worktree with plain git instead.
+      - name: Check out the branch to build
+        if: ${{ inputs.ref != '' }}
+        shell: powershell
+        run: |
+          git fetch --depth=1 origin "${{ inputs.ref }}"
+          git worktree add --force build-src FETCH_HEAD
+          git -C build-src log --oneline -1
+
+      - name: Build the branch
+        if: ${{ inputs.ref != '' }}
+        shell: powershell
+        env:
+          TAURI_SIGNING_PRIVATE_KEY: ${{ secrets.TAURI_SIGNING_PRIVATE_KEY }}
+          TAURI_SIGNING_PRIVATE_KEY_PASSWORD: ''
+          NODE_OPTIONS: '--max_old_space_size=4096'
+          CARGO_REGISTRIES_CRATES_IO_PROTOCOL: sparse
+          CARGO_HTTP_MULTIPLEXING: 'false'
+          CARGO_NET_RETRY: '5'
+        run: |
+          cd build-src
+          git submodule update --init --depth=1
+          cd cinny; npm ci; cd ..
+          node scripts/sync-web-config.mjs
+          npm ci
+          $env:PATH = "$env:USERPROFILE\.cargo\bin;$env:PATH"
+          $toolchain = Get-ChildItem "$env:USERPROFILE\.rustup\toolchains" -Directory -ErrorAction SilentlyContinue |
+                       Where-Object { $_.Name -match 'stable' } | Select-Object -First 1
+          if ($toolchain) { $env:PATH = "$($toolchain.FullName)\bin;$env:PATH" }
+          npm run tauri -- build --bundles nsis
+          New-Item -ItemType Directory -Force -Path ..\smoke-installer | Out-Null
+          $exe = Get-ChildItem src-tauri\target\release\bundle\nsis\*-setup.exe | Select-Object -First 1
+          Copy-Item $exe.FullName ..\smoke-installer\setup.exe
+
+      - name: Install silently
+        shell: powershell
+        run: |
+          Get-Process cinny -ErrorAction SilentlyContinue | Stop-Process -Force
+          Start-Process smoke-installer\setup.exe -ArgumentList '/S' -Wait
+          $app = Join-Path $env:LOCALAPPDATA 'Lotus Chat\cinny.exe'
+          if (-not (Test-Path $app)) { Write-Error "not installed at $app"; exit 1 }
+          (Get-Item $app).VersionInfo | Select-Object ProductVersion, FileVersion
+
+      - name: Start the app and smoke test it
+        shell: powershell
+        run: |
+          New-Item -ItemType Directory -Force -Path smoke-deps | Out-Null
+          Push-Location smoke-deps
+          npm init -y | Out-Null
+          npm install --no-audit --no-fund playwright-core@1 | Out-Null
+          Pop-Location
+          Copy-Item scripts\windows-smoke.mjs smoke-deps\windows-smoke.mjs
+          # Same step as the test: a process started in an earlier step may be
+          # cleaned up when that step ends.
+          # The app sets its own WebView2 arguments, so WebView2's env var doesn't
+          # apply; the app opens the DevTools port itself when asked (#19).
+          $env:LOTUS_WEBVIEW2_DEBUG_PORT = '9222'
+          $app = Join-Path $env:LOCALAPPDATA 'Lotus Chat\cinny.exe'
+          Start-Process $app
+          Start-Sleep -Seconds 15
+          Write-Host "--- processes"
+          Get-Process cinny, msedgewebview2 -ErrorAction SilentlyContinue | Select-Object Name, Id, SessionId | Format-Table | Out-String | Write-Host
+          Write-Host "--- listening ports 9222/44548"
+          Get-NetTCPConnection -State Listen -ErrorAction SilentlyContinue | Where-Object { $_.LocalPort -in 9222, 44548 } | Select-Object LocalAddress, LocalPort, OwningProcess | Format-Table | Out-String | Write-Host
+          Write-Host "--- WebView2 runtime"
+          Get-ItemProperty 'HKLM:\SOFTWARE\WOW6432Node\Microsoft\EdgeUpdate\Clients\{F3017226-FE2A-4295-8BDF-00C3A9A7E4C5}' -ErrorAction SilentlyContinue | Select-Object pv | Out-String | Write-Host
+          Write-Host "--- whoami: $(whoami)"
+          Write-Host "--- webview2 command lines"
+          Get-CimInstance Win32_Process -Filter "Name='msedgewebview2.exe'" | Select-Object -First 2 | ForEach-Object { Write-Host $_.CommandLine.Substring(0, [Math]::Min(600, $_.CommandLine.Length)) }
+          Write-Host "--- netstat"
+          netstat -ano | Select-String "LISTENING" | Select-String ":9222 |:44548 " | ForEach-Object { Write-Host $_ }
+          Write-Host "--- http probes"
+          try { (Invoke-WebRequest -UseBasicParsing http://127.0.0.1:9222/json/version -TimeoutSec 5).Content | Write-Host } catch { Write-Host "9222: $($_.Exception.Message)" }
+          try { (Invoke-WebRequest -UseBasicParsing http://localhost:44548/ -TimeoutSec 5).StatusCode | Write-Host } catch { Write-Host "44548: $($_.Exception.Message)" }
+          node smoke-deps\windows-smoke.mjs smoke-out
+
+      - name: Stop the app
+        if: ${{ always() }}
+        shell: powershell
+        run: |
+          Get-Process cinny -ErrorAction SilentlyContinue | Stop-Process -Force
+          if (Test-Path smoke-out\results.json) { Get-Content smoke-out\results.json }
+
+      - name: Upload results and screenshots
+        if: ${{ always() }}
+        uses: actions/upload-artifact@v3
+        with:
+          name: windows-smoke
+          path: smoke-out

config.json

@@ -24,5 +24,16 @@
     "basename": "/"
   },
   "gifApiKey": "",
-  "webAppUrl": "https://chat.lotusguild.org"
+  "webAppUrl": "https://chat.lotusguild.org",
+  "statusPages": {
+    "matrix.lotusguild.org": {
+      "url": "https://isitup.lotusguild.org",
+      "slug": "matrix",
+      "groups": {
+        "homeserver": "Homeserver",
+        "calls": "Voice calls",
+        "login": "Login"
+      }
+    }
+  }
 }

scripts/windows-smoke.mjs

@@ -0,0 +1,193 @@
+// cinny-desktop #19: Windows smoke test against the INSTALLED app.
+//
+// The app is started with WebView2's DevTools port open
+// (WEBVIEW2_ADDITIONAL_BROWSER_ARGUMENTS=--remote-debugging-port=9222) and this
+// script drives its real page over CDP with playwright-core. No login: every
+// check runs on the login screen or through the app's own Tauri commands.
+//
+//   node scripts/windows-smoke.mjs <outDir>
+//
+// Checks whose feature isn't in the build under test are reported "n/a"
+// instead of failing, so the same script runs on main and on PR branches.
+import { writeFileSync, mkdirSync } from 'node:fs';
+import { execSync } from 'node:child_process';
+import { createServer } from 'node:http';
+import { chromium } from 'playwright-core';
+
+const OUT = process.argv[2] || 'smoke-out';
+mkdirSync(OUT, { recursive: true });
+const APP = 'http://localhost:44548';
+const results = [];
+const record = (name, status, detail = '') => {
+  results.push({ name, status, detail });
+  console.log(`${status.toUpperCase().padEnd(4)} ${name}${detail ? ` — ${detail}` : ''}`);
+};
+
+const until = async (fn, ms, step = 500) => {
+  const end = Date.now() + ms;
+  for (;;) {
+    let v;
+    try {
+      v = await fn();
+    } catch {
+      v = undefined;
+    }
+    if (v || Date.now() > end) return v;
+    await new Promise((r) => setTimeout(r, step));
+  }
+};
+
+// 1. Connect to the running app's WebView2.
+const browser = await until(() => chromium.connectOverCDP('http://127.0.0.1:9222'), 60_000, 1000);
+if (!browser) {
+  record('connect to the app over CDP', 'fail', 'no DevTools endpoint on :9222');
+  writeFileSync(`${OUT}/results.json`, JSON.stringify(results, null, 2));
+  process.exit(1);
+}
+const page = await until(
+  () => browser.contexts().flatMap((c) => c.pages()).find((p) => p.url().startsWith(APP)),
+  60_000,
+);
+if (!page) {
+  record('app page found', 'fail', browser.contexts().flatMap((c) => c.pages()).map((p) => p.url()).join(', '));
+  process.exit(1);
+}
+record('app page found', 'pass', page.url());
+
+// 2. Boots to the login screen.
+const booted = await until(async () => /Login|Homeserver/.test(await page.locator('body').innerText()), 60_000);
+record('boots to the login screen', booted ? 'pass' : 'fail');
+await page.screenshot({ path: `${OUT}/01-login.png` });
+
+// 3. The local server's address (cinny #43 binds 127.0.0.1 explicitly).
+try {
+  const listen = execSync(
+    'powershell -NoProfile -Command "(Get-NetTCPConnection -LocalPort 44548 -State Listen).LocalAddress -join \',\'"',
+  )
+    .toString()
+    .trim();
+  record('local server listening', listen ? 'pass' : 'fail', listen);
+} catch (e) {
+  record('local server listening', 'fail', String(e).slice(0, 120));
+}
+
+const cfg = await page.evaluate(() => fetch('/config.json').then((r) => r.json()));
+
+// 4. Microphone for the app itself (WebView2 PermissionRequested handler, #22).
+const appMic = await page.evaluate(async () => {
+  try {
+    const s = await navigator.mediaDevices.getUserMedia({ audio: true });
+    s.getTracks().forEach((t) => t.stop());
+    return 'ok';
+  } catch (e) {
+    return `${e.name}: ${e.message}`;
+  }
+});
+record('microphone allowed for the app', appMic === 'ok' ? 'pass' : 'fail', appMic);
+
+// 5. Call page on its own origin, isolated from the app (cinny #43 / #27).
+if (cfg.desktopCallOrigin) {
+  const src = `${cfg.desktopCallOrigin}/public/element-call/index.html`;
+  await page.evaluate((s) => {
+    const f = document.createElement('iframe');
+    f.id = 'smoke-call';
+    f.src = s;
+    f.allow = 'microphone; camera; display-capture; autoplay; clipboard-write;';
+    f.sandbox = 'allow-forms allow-scripts allow-same-origin allow-popups allow-modals allow-downloads';
+    document.body.appendChild(f);
+  }, src);
+  const frame = await until(() => page.frames().find((f) => f.url().startsWith(src)), 30_000);
+  if (!frame) {
+    record('call page loads from its own origin', 'fail', 'frame did not load (CSP?)');
+  } else {
+    await frame.waitForLoadState('domcontentloaded').catch(() => undefined);
+    const iso = await frame.evaluate(async () => {
+      const r = { origin: location.origin };
+      try {
+        r.parentStorage = String(parent.localStorage.length);
+      } catch (e) {
+        r.parentStorage = e.name;
+      }
+      try {
+        const s = await navigator.mediaDevices.getUserMedia({ audio: true });
+        s.getTracks().forEach((t) => t.stop());
+        r.mic = 'ok';
+      } catch (e) {
+        r.mic = e.name;
+      }
+      return r;
+    });
+    record('call page loads from its own origin', 'pass', iso.origin);
+    record('call page cannot read the app storage', iso.parentStorage === 'SecurityError' ? 'pass' : 'fail', iso.parentStorage);
+    record('call page gets the microphone', iso.mic === 'ok' ? 'pass' : 'fail', iso.mic);
+  }
+} else {
+  record('call page on its own origin', 'n/a', 'desktopCallOrigin not set in this build');
+}
+
+// 6. OS keychain round trip (cinny #105, step 1).
+const kc = await page.evaluate(async () => {
+  const inv = window.__TAURI_INTERNALS__?.invoke;
+  if (!inv) return { error: 'no Tauri bridge' };
+  try {
+    const supported = await inv('secure_session_supported');
+    if (!supported) return { supported };
+    const tokens = { userId: '@smoke:ci.invalid', deviceId: 'SMOKE', accessToken: `smoke-${Date.now()}` };
+    const before = await inv('secure_session_get');
+    await inv('secure_session_set', { tokens });
+    const back = await inv('secure_session_get');
+    // Put back whatever was there (nothing, on a clean runner).
+    if (before) await inv('secure_session_set', { tokens: before });
+    else await inv('secure_session_clear');
+    const after = await inv('secure_session_get');
+    return { supported, roundTrip: back?.accessToken === tokens.accessToken, restored: JSON.stringify(after) === JSON.stringify(before ?? null) };
+  } catch (e) {
+    return { error: String(e).slice(0, 160) };
+  }
+});
+if (kc.error && /not found/i.test(kc.error)) record('keychain round trip', 'n/a', 'commands not in this build');
+else if (kc.error) record('keychain round trip', 'fail', kc.error);
+else if (!kc.supported) record('keychain round trip', 'fail', 'secure_session_supported = false on Windows');
+else record('keychain round trip', kc.roundTrip && kc.restored ? 'pass' : 'fail', JSON.stringify(kc));
+
+// 7. A foreign page loaded in the window must not get the microphone (#22).
+// Served locally on another port (a different origin, still a secure context),
+// so the check doesn't depend on the runner reaching the internet.
+const foreign = createServer((_, res) => {
+  res.writeHead(200, { 'Content-Type': 'text/html' });
+  res.end('<!doctype html><title>foreign</title>foreign page');
+});
+await new Promise((r) => foreign.listen(9333, '127.0.0.1', r));
+const FOREIGN = 'http://localhost:9333/';
+await page.goto(FOREIGN).catch(() => undefined);
+if (!page.url().startsWith(FOREIGN)) {
+  record('microphone refused to a foreign page', 'fail', `navigation did not happen (at ${page.url()})`);
+} else {
+  const foreignMic = await page.evaluate(async () => {
+    try {
+      const s = await navigator.mediaDevices.getUserMedia({ audio: true });
+      s.getTracks().forEach((t) => t.stop());
+      return 'ok';
+    } catch (e) {
+      return e.name;
+    }
+  });
+  const guarded = cfg.desktopCallOrigin !== undefined; // builds with #22 also carry #43
+  let status = 'info';
+  if (foreignMic === 'NotAllowedError') status = 'pass';
+  else if (guarded) status = 'fail';
+  record(
+    'microphone refused to a foreign page',
+    status,
+    `${foreignMic} at ${page.url()}${status === 'info' ? ' (build without the #22 origin check)' : ''}`,
+  );
+}
+foreign.close();
+await page.goto(APP).catch(() => undefined);
+await page.screenshot({ path: `${OUT}/02-end.png` }).catch(() => undefined);
+
+writeFileSync(`${OUT}/results.json`, JSON.stringify(results, null, 2));
+await browser.close().catch(() => undefined);
+const failed = results.filter((r) => r.status === 'fail');
+console.log(`\n${results.filter((r) => r.status === 'pass').length} passed, ${failed.length} failed`);
+process.exit(failed.length ? 1 : 0);

src-tauri/src/gpu_workarounds.rs

@@ -1,17 +1,22 @@
 //! WebKitGTK workarounds for NVIDIA's proprietary driver on Linux.
 //!
-//! On NVIDIA + Wayland (reported on CachyOS/KDE, driver 615, webkit2gtk 2.52)
-//! the app never shows a window: GDK dies with "Error 71 (Protocol error)
-//! dispatching to Wayland display", and under XWayland WebKit's DMA-BUF
-//! renderer then fails with "Failed to create GBM buffer … Invalid argument".
-//! `WEBKIT_DISABLE_DMABUF_RENDERER=1 GDK_BACKEND=x11` makes it run normally.
+//! Diagnosed on CachyOS/KDE Wayland, RTX 3070, driver 615.71.09, webkit2gtk
+//! 2.52.6 (reported 2026-09-27, WAYLAND_DEBUG trace in the PR):
+//! - Native Wayland: the compositor kills the connection with
+//!   `wp_linux_drm_syncobj_surface_v1 … "explicit sync is used, but no acquire
+//!   point is set"` (GDK: "Error 71 (Protocol error)"), i.e. an explicit-sync
+//!   bug between WebKit and the driver, not a buffer-format problem.
+//!   `__NV_DISABLE_EXPLICIT_SYNC=1` fixes it and keeps WebKit's GPU (DMA-BUF)
+//!   renderer, so that is the default on native Wayland.
+//! - X11 / XWayland: the DMA-BUF renderer can't allocate or import buffers
+//!   ("Failed to create GBM buffer … Invalid argument", "Failed to import
+//!   DMABuf"), so there it is disabled (`WEBKIT_DISABLE_DMABUF_RENDERER=1`,
+//!   shared-memory frames). We never force X11 any more.
 //!
-//! So, before GTK/WebKit initialise, and only when the NVIDIA driver is loaded:
-//! - `WEBKIT_DISABLE_DMABUF_RENDERER=1`;
-//! - on a Wayland session with XWayland available, `GDK_BACKEND=x11`.
-//!
-//! Anything the user already set wins, and `LOTUS_NO_GPU_WORKAROUNDS=1`
-//! disables all of it (e.g. once a newer driver/WebKit fixes this).
+//! Opt-ins / opt-outs (anything the user already set always wins):
+//! - `LOTUS_GPU_SAFE_MODE=1`: last resort, shared-memory rendering on Wayland
+//!   too (slower, especially at high resolutions).
+//! - `LOTUS_NO_GPU_WORKAROUNDS=1`: change nothing.
 
 /// Environment variables to set: pure, for tests.
 pub(crate) fn decide(
@@ -22,15 +27,30 @@ pub(crate) fn decide(
     if !nvidia || set("LOTUS_NO_GPU_WORKAROUNDS") {
         return Vec::new();
     }
-    let mut out = Vec::new();
-    if !set("WEBKIT_DISABLE_DMABUF_RENDERER") {
-        out.push(("WEBKIT_DISABLE_DMABUF_RENDERER", "1"));
-    }
-    let wayland = set("WAYLAND_DISPLAY")
+    let wayland_session = set("WAYLAND_DISPLAY")
         || get("XDG_SESSION_TYPE").is_some_and(|v| v.eq_ignore_ascii_case("wayland"));
-    // Only fall back to X11 when there is an X server (XWayland) to talk to.
-    if wayland && set("DISPLAY") && !set("GDK_BACKEND") {
-        out.push(("GDK_BACKEND", "x11"));
+    // GTK uses Wayland unless GDK_BACKEND says otherwise (it may list
+    // several, e.g. "wayland,x11": the first one wins).
+    let native_wayland = wayland_session
+        && get("GDK_BACKEND").map_or(true, |v| {
+            v.is_empty()
+                || v.trim_start().to_ascii_lowercase().starts_with("wayland")
+                || v.trim() == "*"
+        });
+
+    let mut out = Vec::new();
+    let mut want = |k: &'static str, v: &'static str| {
+        if !set(k) {
+            out.push((k, v));
+        }
+    };
+    if native_wayland {
+        want("__NV_DISABLE_EXPLICIT_SYNC", "1");
+        if set("LOTUS_GPU_SAFE_MODE") {
+            want("WEBKIT_DISABLE_DMABUF_RENDERER", "1");
+        }
+    } else {
+        want("WEBKIT_DISABLE_DMABUF_RENDERER", "1");
     }
     out
 }
@@ -44,9 +64,20 @@ fn nvidia_driver_loaded() -> bool {
 /// Call first thing in `main`, before anything starts GTK or spawns threads.
 pub fn apply() {
     #[cfg(target_os = "linux")]
-    for (key, value) in decide(nvidia_driver_loaded(), |k| std::env::var(k).ok()) {
-        eprintln!("gpu-workarounds: NVIDIA driver detected, setting {key}={value} (LOTUS_NO_GPU_WORKAROUNDS=1 to disable)");
-        std::env::set_var(key, value);
+    {
+        let changes = decide(nvidia_driver_loaded(), |k| std::env::var(k).ok());
+        if changes.is_empty() {
+            return;
+        }
+        let list: Vec<String> = changes.iter().map(|(k, v)| format!("{k}={v}")).collect();
+        eprintln!(
+            "gpu-workarounds: NVIDIA driver detected, setting {} \
+             (LOTUS_GPU_SAFE_MODE=1 for shared-memory rendering, LOTUS_NO_GPU_WORKAROUNDS=1 to disable)",
+            list.join(" ")
+        );
+        for (key, value) in changes {
+            std::env::set_var(key, value);
+        }
     }
 }
 
@@ -71,51 +102,70 @@ mod tests {
     }
 
     #[test]
-    fn nvidia_wayland_gets_both() {
+    fn nvidia_wayland_keeps_gpu_renderer_and_disables_explicit_sync() {
         assert_eq!(
             run(true, WAYLAND),
-            vec![
-                ("WEBKIT_DISABLE_DMABUF_RENDERER", "1"),
-                ("GDK_BACKEND", "x11")
-            ]
+            vec![("__NV_DISABLE_EXPLICIT_SYNC", "1")]
         );
     }
 
     #[test]
-    fn nvidia_x11_session_only_disables_dmabuf() {
-        assert_eq!(
-            run(true, &[("DISPLAY", ":0")]),
-            vec![("WEBKIT_DISABLE_DMABUF_RENDERER", "1")]
-        );
-    }
-
-    #[test]
-    fn wayland_without_xwayland_keeps_wayland() {
-        assert_eq!(
-            run(true, &[("WAYLAND_DISPLAY", "wayland-0")]),
-            vec![("WEBKIT_DISABLE_DMABUF_RENDERER", "1")]
-        );
+    fn never_forces_x11() {
+        for env in [
+            WAYLAND,
+            &[("DISPLAY", ":0")][..],
+            &[("WAYLAND_DISPLAY", "w")][..],
+        ] {
+            assert!(run(true, env).iter().all(|(k, _)| *k != "GDK_BACKEND"));
+        }
     }
 
     #[test]
     fn xdg_session_type_counts_as_wayland() {
         assert_eq!(
-            run(true, &[("XDG_SESSION_TYPE", "wayland"), ("DISPLAY", ":1")]),
+            run(true, &[("XDG_SESSION_TYPE", "wayland")]),
+            vec![("__NV_DISABLE_EXPLICIT_SYNC", "1")]
+        );
+    }
+
+    #[test]
+    fn nvidia_x11_session_disables_dmabuf_renderer() {
+        assert_eq!(
+            run(true, &[("DISPLAY", ":0"), ("XDG_SESSION_TYPE", "x11")]),
+            vec![("WEBKIT_DISABLE_DMABUF_RENDERER", "1")]
+        );
+    }
+
+    #[test]
+    fn user_forced_x11_on_wayland_counts_as_x11() {
+        let mut env = WAYLAND.to_vec();
+        env.push(("GDK_BACKEND", "x11"));
+        assert_eq!(
+            run(true, &env),
+            vec![("WEBKIT_DISABLE_DMABUF_RENDERER", "1")]
+        );
+        let mut env = WAYLAND.to_vec();
+        env.push(("GDK_BACKEND", "wayland,x11"));
+        assert_eq!(run(true, &env), vec![("__NV_DISABLE_EXPLICIT_SYNC", "1")]);
+    }
+
+    #[test]
+    fn safe_mode_adds_shared_memory_rendering_on_wayland() {
+        let mut env = WAYLAND.to_vec();
+        env.push(("LOTUS_GPU_SAFE_MODE", "1"));
+        assert_eq!(
+            run(true, &env),
             vec![
-                ("WEBKIT_DISABLE_DMABUF_RENDERER", "1"),
-                ("GDK_BACKEND", "x11")
+                ("__NV_DISABLE_EXPLICIT_SYNC", "1"),
+                ("WEBKIT_DISABLE_DMABUF_RENDERER", "1")
             ]
         );
     }
 
     #[test]
     fn user_settings_win() {
-        let env = [
-            ("WAYLAND_DISPLAY", "wayland-0"),
-            ("DISPLAY", ":0"),
-            ("WEBKIT_DISABLE_DMABUF_RENDERER", "0"),
-            ("GDK_BACKEND", "wayland"),
-        ];
+        let mut env = WAYLAND.to_vec();
+        env.push(("__NV_DISABLE_EXPLICIT_SYNC", "0"));
         assert!(run(true, &env).is_empty());
     }
 

src-tauri/src/lib.rs

@@ -1128,9 +1128,9 @@ pub fn run() {
                 // Tauri's default WebView2 args (setting this overrides them) and
                 // appends the Chromium background-throttling disables. Windows-only
                 // in effect; harmless elsewhere. Does not block system sleep.
-                .additional_browser_args(
-                    "--disable-features=msWebOOUI,msPdfOOUI --disable-background-timer-throttling --disable-renderer-backgrounding --disable-backgrounding-occluded-windows",
-                )
+                .additional_browser_args(&webview2_browser_args(
+                    std::env::var("LOTUS_WEBVIEW2_DEBUG_PORT").ok().as_deref(),
+                ))
                 .on_page_load(move |window, payload| {
                     if matches!(payload.event(), PageLoadEvent::Finished) {
                         // Reveal only on the FIRST settle: later page loads (e.g. a
@@ -1289,6 +1289,50 @@ pub fn run() {
         .expect("error while building tauri application");
 }
 
+/// WebView2 browser arguments. Setting them replaces Tauri's defaults, so
+/// they're kept, plus the Chromium background-throttling disables (P5-42).
+///
+/// cinny-desktop #19: `LOTUS_WEBVIEW2_DEBUG_PORT=<port>` in the environment
+/// opens WebView2's DevTools port on localhost so the Windows smoke test can
+/// drive the installed app, and gives it Chromium's fake capture devices (the
+/// CI VM has no microphone; permission requests still go through the app's
+/// real PermissionRequested handler). WebView2's own
+/// `WEBVIEW2_ADDITIONAL_BROWSER_ARGUMENTS` doesn't apply because the app sets
+/// its arguments explicitly. Off unless the variable holds a valid port; only
+/// whoever launches the app can set it.
+pub(crate) fn webview2_browser_args(debug_port: Option<&str>) -> String {
+    let mut args = String::from(
+        "--disable-features=msWebOOUI,msPdfOOUI --disable-background-timer-throttling --disable-renderer-backgrounding --disable-backgrounding-occluded-windows",
+    );
+    if let Some(port) = debug_port
+        .and_then(|p| p.trim().parse::<u16>().ok())
+        .filter(|p| *p >= 1024)
+    {
+        eprintln!("webview: DevTools port {port} open (LOTUS_WEBVIEW2_DEBUG_PORT)");
+        args.push_str(&format!(
+            " --remote-debugging-port={port} --use-fake-device-for-media-stream"
+        ));
+    }
+    args
+}
+
+#[cfg(test)]
+mod webview2_args_tests {
+    use super::webview2_browser_args;
+
+    #[test]
+    fn debug_port_only_when_asked_for_and_valid() {
+        let base = webview2_browser_args(None);
+        assert!(base.contains("--disable-renderer-backgrounding"));
+        assert!(!base.contains("remote-debugging"));
+        assert!(webview2_browser_args(Some("9222"))
+            .ends_with(" --remote-debugging-port=9222 --use-fake-device-for-media-stream"));
+        for bad in ["", "abc", "80", "70000", "9222 --evil", "-1"] {
+            assert_eq!(webview2_browser_args(Some(bad)), base, "{bad}");
+        }
+    }
+}
+
 #[cfg(test)]
 mod tray_tests {
     use super::*;