feat(notifications): desktop and mobile notifications with Web Push

[andrebrait]

Summary

Adds Settings → Notifications: desktop and mobile (PWA) notifications for

• Task finished: the prompt and any background work it started are done (session_settled). Subagents never notify.
• Waiting for input: an ask question, a confirmation, or any other blocking dialog.
• Run failed: prompt_result with status: "error" after omp's retries and fallbacks, or the omp process crashing mid-run.
• Model switched automatically: retry_fallback_applied (refusal, rate limit, usage limit; for example Fable → Opus) and prewalk / plan hand-offs. The reason comes from the retry error omp sends right after the fallback.

Each browser picks its own event types and what happens while you use omp-web in another tab: an in-app toast (default) or always a system notification. Nothing is shown for the session you are viewing, and clicking a notification opens its session.

How it works

• Detection runs on the server in AgentSessionWrapper.handleFrame, so sessions no tab is watching still notify.
• Tabs report presence (visible, recent input, shown session). The server routes each event to a toast, an in-page system notification, or a Web Push (web-push, VAPID keys generated on first use in ~/.omp/agent/omp-web/notifications.json, mode 0600).
• Toasts and in-page notifications ride the existing /api/agent/running/events stream, so a tab opens no extra connection.
• public/sw.js shows pushes with our icon and a monochrome status-bar badge, and opens the session on click.
• Push needs HTTPS (or localhost). iOS/iPadOS needs the Home Screen app. Over plain HTTP on a LAN address, only in-app toasts work.

The previous foreground-only completion notification is removed (noted in the CHANGELOG). The notify host tool now goes through the service worker, so it also works on Android.

Design spec: docs/specs/2026-10-06-notifications-design.md.

Verification

• npm run typecheck, npm run lint (no new warnings), npm test: 1,252 tests, 0 failures. New tests cover the detector, the routing rules, push storage and failure handling, and the rpc-manager wiring.
• Live smoke against omp 18.6.2 in headless Chromium on localhost, with real Web Push through FCM:
  • test push;
  • toast with Open, which opened the session;
  • no notification for the viewed session;
  • push in "always system" mode and while Settings is open;
  • "Waiting for your answer: Deploy now?" from a real ask call;
  • push subscription restored after the server store was deleted.
• One condensed adversarial review round, then Codex and CodeRabbit on the review companion ([companion] feat(notifications): desktop and mobile notifications with Web Push andrebrait/ompweb#78); all findings are fixed in the follow-up commits.

Not done:

• No pushsubscriptionchange handler: a browser-rotated subscription is repaired on the next app load.
• Push endpoints are restricted to https: but not to public hosts (authenticated users already run agents with shell access).

[kahme247]

Review — approve (SHIP)

Verified by independent review in a scratch worktree plus lead checks. All claims hold.

Web Push (#218). VAPID private key never leaves the server (0600 store file; only {publicKey, subscribed} crosses the wire). All four endpoints sit behind the proxy.ts session-cookie gate; the two new matcher entries (/sw.js, /badge-96.png) are static and data-free. Stores bounded (MAX_DEVICES 50, presence pruned on read, zero server timers). Typecheck clean, targeted suites 93/93, mutations killed. The one real item is the #230 collision (below) — clean in isolation.

Coordinated merge note for #218 + #230: exactly one textual hunk (AppShell.handleAgentEnd) plus two silent breakages — #218 deletes lib/browser-notifications.ts that #230 still imports, and the appShell.sessionComplete/taskFinished keys #230 still translates. Resolution: land #230 first, resolve the hunk in favor of #218's useNotifications delivery, drop #230's handleAgentEnd record calls. History coverage then comes free (#218's showToast calls carry {id: tag}, which #230 auto-records with dedup). No duplicate centers, no unrenderable shapes.