feat(plugin): voice-message mic UI in app.js — closes Phase 2.A UX gap (L8)

Migrates the boot.js mic-button behavior change from reverted fork commit
014b9eef into plugin/static/app.js. Replaces vanilla dictation-to-textbox
mic flow with voice-message mode: tap to record, tap again to stop → audio
File attached + sent automatically. Server-side audio_attachment_processor
in routes/transcribe.py transcribes for text-only models.

Implementation strategy:
- Own #btnMic onclick (boot.js sets it during init; plugin overrides via
  MutationObserver after DOM mutations + idempotent dataset.svrntyVm flag)
- MediaRecorder with same mime-type fallbacks as the original
  (webm/opus → webm → ogg/opus → mp4)
- DataTransfer to set #fileInput.files programmatically (cross-browser path)
- Dispatch 'change' so boot.js's fileInput.onchange → addFiles() runs
- Click #btnSend after 50ms tick so attachment registers before submit

Filename convention: voice-message-${timestamp}.{webm|ogg|mp4} — matches the
audio processor's name-prefix detection in _transcribe_audio_attachments.

Tests: 6 new JS-static checks in tests/unit/test_app_js.py (idempotent
guard, voice-message prefix, DataTransfer pattern, vault URL pin, mic
override). 26 tests total, all PASS.

Connection map: now 9 public API · 0 forced internal · 1 frontend.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

static/app.js

@@ -6,6 +6,125 @@
   if (window.__svrntyExtLoaded) return;
   window.__svrntyExtLoaded = true;
 
+  // ── Voice-message mic mode (migrated from fork commit 014b9eef) ─────────
+  // Replaces vanilla dictation-to-textbox mic flow with voice-message mode:
+  // tap to record, tap again to stop → file attached + sent automatically.
+  // The server-side audio_attachment_processor in routes/transcribe.py
+  // transcribes it so text-only models can read voice messages.
+  //
+  // Strategy: replace #btnMic onclick handler (set by boot.js) with our own
+  // MediaRecorder flow. Programmatically inject the recorded File into
+  // #fileInput via DataTransfer + dispatch change event (boot.js's onchange
+  // calls addFiles automatically). Then click #btnSend to submit.
+  let _vmRecorder = null;
+  let _vmStream = null;
+  let _vmChunks = [];
+  let _vmRecording = false;
+
+  function _vmStopTracks() {
+    if (_vmStream) {
+      try { _vmStream.getTracks().forEach((t) => t.stop()); } catch (_) { /* ignore */ }
+      _vmStream = null;
+    }
+  }
+
+  async function _vmStart(btn, status) {
+    if (!navigator.mediaDevices || !window.MediaRecorder) {
+      console.warn("[svrnty] MediaRecorder unavailable; voice-message disabled");
+      return false;
+    }
+    try {
+      _vmStream = await navigator.mediaDevices.getUserMedia({ audio: true });
+    } catch (e) {
+      console.warn("[svrnty] mic permission denied:", e && e.message);
+      return false;
+    }
+    const preferred = ["audio/webm;codecs=opus", "audio/webm", "audio/ogg;codecs=opus", "audio/mp4"];
+    const mime = preferred.find((t) => window.MediaRecorder.isTypeSupported && window.MediaRecorder.isTypeSupported(t)) || "";
+    _vmRecorder = new MediaRecorder(_vmStream, mime ? { mimeType: mime } : undefined);
+    _vmChunks = [];
+    _vmRecorder.ondataavailable = (e) => { if (e.data && e.data.size) _vmChunks.push(e.data); };
+    _vmRecorder.onerror = () => { _vmRecording = false; _vmStopTracks(); _vmSetUI(btn, status, false); };
+    _vmRecorder.onstop = () => {
+      _vmRecording = false;
+      _vmSetUI(btn, status, false);
+      const blob = new Blob(_vmChunks, { type: _vmRecorder.mimeType || mime || "audio/webm" });
+      _vmStopTracks();
+      if (!blob.size) return;
+      _vmAttachAndSend(blob);
+    };
+    _vmRecorder.start();
+    _vmRecording = true;
+    _vmSetUI(btn, status, true);
+    return true;
+  }
+
+  function _vmStop() {
+    if (_vmRecorder && _vmRecorder.state !== "inactive") {
+      try { _vmRecorder.stop(); } catch (_) { /* ignore */ }
+    }
+  }
+
+  function _vmSetUI(btn, status, on) {
+    if (btn) btn.classList.toggle("recording", !!on);
+    if (status) status.textContent = on ? "Recording…" : "";
+  }
+
+  function _vmAttachAndSend(blob) {
+    // Pick extension matching mime so the server-side filename detection
+    // (voice-message-* + audio extension) triggers the audio processor.
+    const bt = blob.type || "";
+    const ext = bt.includes("mp4") ? "mp4" : bt.includes("ogg") ? "ogg" : "webm";
+    const filename = `voice-message-${Date.now()}.${ext}`;
+    const file = new File([blob], filename, { type: bt || `audio/${ext}` });
+
+    const fileInput = document.getElementById("fileInput");
+    const btnSend = document.getElementById("btnSend");
+    if (!fileInput || !btnSend) {
+      console.warn("[svrnty] composer file input or send button missing");
+      return;
+    }
+    // DataTransfer trick to set FileList programmatically (Chrome/Firefox/Safari).
+    const dt = new DataTransfer();
+    dt.items.add(file);
+    fileInput.files = dt.files;
+    fileInput.dispatchEvent(new Event("change", { bubbles: true }));
+    // Wait one tick so addFiles() processes the attachment, then send.
+    setTimeout(() => { try { btnSend.click(); } catch (_) { /* ignore */ } }, 50);
+  }
+
+  function _vmInstall() {
+    const btn = document.getElementById("btnMic");
+    if (!btn || btn.dataset.svrntyVm === "1") return;
+    btn.dataset.svrntyVm = "1";
+    const status = document.getElementById("micStatus");
+    // Replace boot.js's onclick. We own the mic now.
+    btn.onclick = async (e) => {
+      if (e && e.preventDefault) e.preventDefault();
+      if (_vmRecording) {
+        _vmStop();
+      } else {
+        const ok = await _vmStart(btn, status);
+        if (!ok) console.warn("[svrnty] voice-message recording start failed");
+      }
+    };
+  }
+
+  function _vmHook() {
+    // boot.js sets btn.onclick in its IIFE that runs at DOMContentLoaded; we
+    // override after a microtask so our handler wins. Also re-install on
+    // future DOM mutations (some session-switching flows rebuild the bar).
+    _vmInstall();
+    const observer = new MutationObserver(() => _vmInstall());
+    observer.observe(document.body, { childList: true, subtree: true });
+  }
+
+  if (document.readyState === "loading") {
+    document.addEventListener("DOMContentLoaded", _vmHook);
+  } else {
+    _vmHook();
+  }
+
   // ── Vault status panel (migrated from fork commit 3e2c74f3) ─────────────
   // Injects a "Vault connections" section into Settings → System on demand,
   // populates it from GET /api/vault/status (served by plugin/routes/vault_status.py).