feat(v0.7): Walk-away Workbench (Band A + B) — multi-agent parallel build

Implements docs/PLAN_WALKAWAY_WORKBENCH.md (27 tasks, waves R0→W0→W1×14→W2→W3→W4)
via module-builder agents. 23 tasks built, 0 blocked.

Band A (finish the walk-away loop): A1 Web Push + lock-screen approve/deny
(web-push dep), A2 voice dictation, A3 quick-reply chips + saved-prompt palette,
A4 activity timeline, A5 stuck/idle alert.
Band B (workbench above the terminal): B1 read-only git diff viewer, B2 statusLine
telemetry → per-tab cost/context/PR gauges, B3 create git worktrees from the UI,
B4 plan-mode / permission-mode relay.

New: src/push/* (subscription store + VAPID push), src/http/{diff,statusline}.ts,
src/session/timeline.ts, public/{diff,timeline,quickreply,push-ui,...}.ts, sw-push,
statusLine script; extends hook intake, manager, server routes (Origin/CSRF guards
+ per-IP rate limits on state-changing ones; loopback-only ingest), terminal-session,
tabs, projects detail, service worker, setup-hooks (statusLine + ntfy bridge).

Orchestrator reconciled a W0 contract gap: added the 21 v0.7 Config fields to the
Config interface in types.ts (T-types had left them only in config.ts's return).

Verified: both tsc clean, full vitest + coverage 91.4/84.1/92.2/93.4 (≥80×4),
build:web OK. W4 review: no CRITICAL/HIGH; all security checks pass. Follow-ups
(non-blocking): move approve.mode validation into parseClientMessage, drop CSP
ws:/wss: wildcard, validate worktree base ref, +2 targeted tests.

public/sw.js

@@ -1,10 +1,16 @@
 /**
- * public/sw.js — minimal service worker (M4: PWA installability + offline shell).
+ * public/sw.js — service worker (ES module; must be registered with {type:'module'}).
  *
- * Network-first so we never serve a stale build while online; falls back to the
- * cache when offline. Never intercepts the WebSocket (/term) or hook endpoints.
+ * Network-first caching + A1 push notifications + notificationclick routing.
+ * Pure push/notification helpers live in sw-push.js (no SW globals → testable).
+ *
+ * IMPORTANT: This file uses ES module `import` syntax. The SW registration in
+ * public/main.ts must pass { type: 'module' }:
+ *   navigator.serviceWorker.register('./sw.js', { type: 'module' })
  */
 
+import { buildPushNotification, resolveNotificationClick } from './sw-push.js'
+
 const CACHE = 'webterm-v1'
 
 self.addEventListener('install', () => self.skipWaiting())
@@ -14,7 +20,13 @@ self.addEventListener('fetch', (e) => {
   const req = e.request
   if (req.method !== 'GET') return
   const url = new URL(req.url)
-  if (url.pathname === '/term' || url.pathname.startsWith('/hook')) return // WS / hooks
+  // Bypass: WS upgrade, hook endpoints, and push subscription routes (A1)
+  if (
+    url.pathname === '/term' ||
+    url.pathname.startsWith('/hook') ||
+    url.pathname.startsWith('/push')
+  )
+    return
 
   e.respondWith(
     fetch(req)
@@ -26,3 +38,54 @@ self.addEventListener('fetch', (e) => {
       .catch(() => caches.match(req)),
   )
 })
+
+/** A1: show a notification when a push arrives. */
+self.addEventListener('push', (e) => {
+  let payload
+  try {
+    payload = e.data?.json()
+  } catch {
+    return // malformed push — ignore
+  }
+  if (!payload || typeof payload !== 'object') return
+
+  const { title, options } = buildPushNotification(payload)
+  e.waitUntil(self.registration.showNotification(title, options))
+})
+
+/**
+ * A1: handle notification action clicks.
+ * Allow/Deny → POST /hook/decision with capability token (SEC-C1).
+ * Body click  → focus / open the terminal session tab.
+ */
+self.addEventListener('notificationclick', (e) => {
+  e.notification.close()
+  const result = resolveNotificationClick(e.notification, e.action)
+
+  if (result.kind === 'decision') {
+    // credentials:'same-origin' ensures Origin header is sent so the server
+    // can validate it alongside the capability token (SEC-C1).
+    e.waitUntil(
+      fetch('/hook/decision', {
+        method: 'POST',
+        headers: { 'Content-Type': 'application/json' },
+        credentials: 'same-origin',
+        body: result.body,
+      }).catch((err) => {
+        console.error('[sw] /hook/decision fetch failed', err)
+      }),
+    )
+  } else {
+    // Focus an existing window if available, otherwise open a new one.
+    e.waitUntil(
+      self.clients
+        .matchAll({ type: 'window', includeUncontrolled: true })
+        .then((clientList) => {
+          for (const client of clientList) {
+            if ('focus' in client) return client.focus()
+          }
+          return self.clients.openWindow(result.url)
+        }),
+    )
+  }
+})