feat(desktop): session hygiene, archive, media streaming + connecting overlay (#37099)

* feat(desktop): session hygiene, archive, media streaming + connecting overlay

Address a batch of desktop feedback:

- Stop leaking empty "Untitled" sessions: the TUI gateway pre-created a DB
  row on every session.create (i.e. every launch/draft). Persist the row
  lazily on first prompt instead, and hide message-less rows in the sidebar.
- Archive/hide sessions: new `archived` column + set_session_archived, web
  API (`?archived=` + PATCH archived), Ctrl/⌘-click and a context-menu item
  in the sidebar, and an "Archived Chats" settings panel to restore/delete.
- Videos load via a streaming `hermes-media://` protocol instead of capped,
  in-memory data URLs (16 MB limit) — bypasses the cap and supports seeking.
- Background-process completions route to the session that launched them:
  the completion event now carries session_key and each poller only consumes
  its own.
- Sidebar: "Group by workspace" toggle is always visible; each workspace
  group gets a "+" to start a session in that directory; "New agent"/"Agents"
  relabeled to "New session"/"Sessions".
- New gateway connecting overlay (ascii decode → fade out) replacing the bare
  skeleton/"starting gateway" state.

* fix(desktop): bail connecting overlay on boot error

The shownRef latch kept the connecting overlay mounted behind
BootFailureOverlay after a hard boot failure. Return null on boot.error
so the failure recovery surface fully owns the screen.

* fix(desktop): address Copilot review

- /api/sessions: validate `archived` (400 on unknown) and return `archived`
  as a JSON boolean instead of SQLite's 0/1.
- PATCH /api/sessions/{id}: 400 (not a misleading 404) when the body has no
  updatable fields; stop conflating a no-op with "not found".
- hermes-media protocol: drop `bypassCSP` — streaming only needs
  secure/standard/stream/supportFetchAPI.
- Sidebar workspace header: split the toggle and the "+" into sibling buttons
  so we no longer nest interactive elements inside a <button>.

* fix(desktop): address Copilot re-review

- hermes-media protocol: restrict streaming to an audio/video extension
  allowlist (415 otherwise) so it can't be used to read arbitrary local files.
- Connecting overlay: use z-[1200] instead of the non-standard z-1200 utility.

* Potential fix for pull request finding

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

apps/desktop/electron/main.cjs

@@ -8,6 +8,8 @@ const {
   ipcMain,
   nativeImage,
   nativeTheme,
+  net: electronNet,
+  protocol,
   safeStorage,
   session,
   shell,
@@ -364,6 +366,66 @@ app.setAboutPanelOptions({
   copyright: 'Copyright © 2026 Nous Research'
 })
 
+// Custom scheme for streaming local media (video/audio) into the renderer.
+// Reading large media through `readFileDataUrl` failed: it base64-loads the
+// whole file into memory and is hard-capped at DATA_URL_READ_MAX_BYTES (16 MB),
+// so any non-trivial video silently refused to load. Streaming via a protocol
+// handler removes the size cap and gives the <video> element seekable,
+// range-aware playback. Must be registered before the app is ready.
+const MEDIA_PROTOCOL = 'hermes-media'
+// Only audio/video may be streamed. Without this the handler would read any
+// non-blocklisted local file (no size cap) for any `fetch(hermes-media://…)`.
+const STREAMABLE_MEDIA_EXTS = new Set([
+  '.avi',
+  '.flac',
+  '.m4a',
+  '.mkv',
+  '.mov',
+  '.mp3',
+  '.mp4',
+  '.ogg',
+  '.opus',
+  '.wav',
+  '.webm'
+])
+
+protocol.registerSchemesAsPrivileged([
+  {
+    scheme: MEDIA_PROTOCOL,
+    privileges: {
+      secure: true,
+      standard: true,
+      stream: true,
+      supportFetchAPI: true
+    }
+  }
+])
+
+function registerMediaProtocol() {
+  protocol.handle(MEDIA_PROTOCOL, async request => {
+    let resolvedPath
+    try {
+      const url = new URL(request.url)
+      const filePath = decodeURIComponent(url.pathname.replace(/^\/+/, ''))
+      ;({ resolvedPath } = await resolveReadableFileForIpc(filePath, { purpose: 'Media stream' }))
+    } catch {
+      return new Response('Media not found', { status: 404 })
+    }
+
+    if (!STREAMABLE_MEDIA_EXTS.has(path.extname(resolvedPath).toLowerCase())) {
+      return new Response('Unsupported media type', { status: 415 })
+    }
+
+    // Delegate to Electron's net stack on a file:// URL — it resolves the
+    // content-type and honors Range requests so seeking works. Forward the
+    // renderer's headers (notably Range) and skip custom-protocol re-entry.
+    return electronNet.fetch(pathToFileURL(resolvedPath).toString(), {
+      bypassCustomProtocolHandlers: true,
+      headers: request.headers
+    })
+  })
+}
+
 let mainWindow = null
 let hermesProcess = null
 let connectionPromise = null
@@ -3654,6 +3716,7 @@ app.whenReady().then(() => {
     Menu.setApplicationMenu(null)
   }
   installMediaPermissions()
+  registerMediaProtocol()
   ensureWslWindowsFonts()
   createWindow()