feat(web): closed-tab Web Push notifications (SW + PWA + server VAPID push)

[radroid]

Closes #19

What

Closes the accepted v1 gap from #14 (in-tab notifications only): deliver a browser notification when the T3 tab is fully closed, via a service worker + PWA manifest + server-side Web Push.

Client (apps/web)

• PWA manifest + 192/512 icons + iOS meta (installability; iOS Safari Web Push requires an installed PWA).
• Push-only service worker (public/sw.js) — deliberately no fetch handler (not an offline PWA; avoids stale-asset risk). Shows on push, focuses/opens the waiting thread on notificationclick, and suppresses when any T3 tab is open so the merged in-page NotificationCoordinator stays the single source while a tab is alive.
• PushSubscriptionManager keeps the subscription in sync with the existing notifyOnNeedsInput setting + permission (reacts to a post-mount grant via the Permissions API). Pure, unit-tested VAPID/subscription helpers (push.logic.ts).

Server (apps/server/src/t3x/webPush, fork-seam clean)

Mirrors the auto-resume feature: zero edits to upstream-owned files (contracts / ws.ts / http.ts / Migrations.ts / server.ts). Everything mounts through the existing T3xLayerLive + T3xRoutesLive seams.

• Reactor taps OrchestrationEngine.streamDomainEvents, recomputes the awareness phase with the shared projectThreadAwareness, edge-detects the same transitions the web client does (waiting_for_input / waiting_for_approval; running → completed), and sends Web Push to registered subscriptions, pruning expired (404/410) ones.
• JSON subscription store in the state dir (keyed by endpoint) — no DB migration.
• VAPID keypair via ServerSecretStore (generated + persisted on first boot; T3X_VAPID_PUBLIC_KEY/T3X_VAPID_PRIVATE_KEY/T3X_VAPID_SUBJECT env override supported).
• Raw routes GET/POST /api/t3x/push/{vapid-public-key,subscribe,unsubscribe} (read/operate scoped), called from the client exactly like AutoResumeOverlay calls /api/t3x/auto-resume.

Identity note

apps/server is single-user/single-environment (no Clerk server-side), so subscriptions key by auth session (device); "notify me" = push to all subscriptions in the environment.

Verified

• apps/web + apps/server typecheck clean (0 errors).
• Unit tests pass: web push.logic (7), server attention edge-tracker + suite (157).
• web-push loads at runtime (VAPID generation OK); server + bin construction tests (277) pass with the reactor/routes wired in.

Manual QA (needs a real browser + push service — not automatable here)

1. Open T3 over HTTPS (the Tailscale URL works); grant notification permission; on iPhone add to Home Screen.
2. Start an agent turn, then close the tab; when the agent needs input / completes, confirm a push arrives and clicking it opens the thread.
3. With a tab open, confirm no duplicate (in-page path handles it).

Deliberate v1 tradeoffs

• De-dup is service-worker-side (suppress when a tab is open). When a tab is open but backgrounded, the push is received-but-not-shown; Chrome's silent-push budget makes this fine at this low volume, but a future refinement is server-side presence gating.
• Multi-device: push goes to all registered devices; per-device presence isn't tracked yet.

🤖 Generated with Claude Code

[coderabbitai]

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[radroid]

Adversarial self-review + fixes

Ran an adversarial review of this branch and pushed fixes for the actionable findings:

• Reactor priming (medium): the store-empty short-circuit ran before tracker.observe, so the first transition after a device subscribed could be swallowed as first-seen. Now observes the phase unconditionally and gates only the send on subscription count. Also added a conservative event denylist (skip meta/mode-change events) so we don't refetch the shell on every domain event.
• VAPID recovery (medium): if the server's VAPID key ever changes, old subscriptions became permanently undeliverable with no recovery. Now the client re-subscribes when an existing subscription's applicationServerKey ≠ the current server key, and the server also prunes on 403 (not just 404/410).
• Permission-revoked cleanup (low): unsubscribe server-side when notification permission flips to denied while the setting stays on.
• Malformed body (low): a non-JSON request body now returns 400 instead of 500.

Known v1 limitations (documented, not blocking)

• SW de-dup vs. silent-push budget: the service worker suppresses when any T3 tab is open (so notifications are never doubled), which means a push received while a tab is open shows nothing. Chrome's silent-push budget tolerates this at low volume, but the clean long-term fix is server-side presence gating (skip pushing to a device whose auth session has a live connection). Edge: if the only open tab is on a route that doesn't mount the in-page coordinator (e.g. /pair), that push is suppressed without an in-page fallback.
• Post-auth subscribe timing: if the very first subscribe attempt races primary-environment auth it no-ops until the next permission/setting change; narrow and usually masked.

Verification: both packages typecheck clean (0 errors); web + server unit tests pass; web-push loads at runtime; server+bin construction tests (277) pass. Browser end-to-end remains manual QA.