feat(cockpit): quick wins — sync chip, cost budget guard, digest, recent commits (W3)

Four small, high-delight features that turn passive capture into glanceable signals.

- Sync chip on project cards: ahead/behind vs upstream + last-commit time, folded
  into the existing concurrent per-repo metadata pass (git rev-list --count
  --left-right @{u}...HEAD + git log -1 --format=%ct; no upstream → undefined, no route).
- Cost budget guard: COST_BUDGET_USD env (0 = off); a per-session one-shot latch
  (Session.budgetNotified, cost is monotonic so never re-armed) fires a single push
  on threshold crossing in manager.handleStatusLine; the already-broadcast telemetry
  frame carries the warn (tg-cost-warn styling derived from costUsd>=budget via
  /config/ui — no new ServerMessage). web-push title added to sw-push.js.
- "While you were away" digest: GET /digest?since= → {finished, needsInput, stuck,
  totalCostUsd, sessions[]} aggregate over manager.list(); FE banner on reconnect.
- Recent commits per project: src/http/git-log.ts (NUL-delimited git log → CommitInfo[]),
  GET /projects/log?path= (isValidGitDir), textContent-inert render in project detail.

All git via execFile (no shell) + validated cwd; new routes read-only; commit
messages rendered via textContent. Verified: typecheck + build:web clean, 1904 pass
at --test-timeout=30000 (two default-5s failures are slow-sandbox real-subprocess
timeout flakes — the known ring-buffer test + a new real-git-clone sync test — not
logic regressions).

test/http/digest.test.ts

@@ -0,0 +1,114 @@
+/**
+ * test/http/digest.test.ts (W3 quick-wins c) — buildDigest read-side aggregate.
+ *
+ * Pure over an injected LiveSessionInfo[] (mirrors buildProjects injection):
+ * counts finished (idle & lastOutputAt > since), needsInput (waiting), stuck,
+ * working; sums telemetry.costUsd; empty → zeroes; future `since` → 0 finished;
+ * bad `since` clamps to 0.
+ */
+
+import { describe, it, expect } from 'vitest'
+import type { LiveSessionInfo, ClaudeStatus } from '../../src/types.js'
+import { buildDigest, clampSince } from '../../src/http/digest.js'
+
+function live(over: Partial<LiveSessionInfo> & { id: string; status: ClaudeStatus }): LiveSessionInfo {
+  return {
+    createdAt: 1000,
+    clientCount: 0,
+    exited: false,
+    cwd: null,
+    cols: 80,
+    rows: 24,
+    ...over,
+  }
+}
+
+// ── clampSince ────────────────────────────────────────────────────────────────
+
+describe('clampSince', () => {
+  it('passes through a finite non-negative number', () => {
+    expect(clampSince(1234)).toBe(1234)
+    expect(clampSince(0)).toBe(0)
+  })
+
+  it('clamps NaN / negative / non-numeric / undefined to 0', () => {
+    expect(clampSince(NaN)).toBe(0)
+    expect(clampSince(-5)).toBe(0)
+    expect(clampSince('abc')).toBe(0)
+    expect(clampSince(undefined)).toBe(0)
+  })
+
+  it('parses a numeric string', () => {
+    expect(clampSince('42')).toBe(42)
+  })
+})
+
+// ── buildDigest ───────────────────────────────────────────────────────────────
+
+describe('buildDigest', () => {
+  it('returns an all-zero aggregate for an empty list', () => {
+    const d = buildDigest([], 0)
+    expect(d).toMatchObject({
+      since: 0,
+      total: 0,
+      finished: 0,
+      needsInput: 0,
+      stuck: 0,
+      working: 0,
+      totalCostUsd: 0,
+      sessions: [],
+    })
+    expect(typeof d.generatedAt).toBe('number')
+  })
+
+  it('counts finished (idle + output after since), needsInput, stuck, working', () => {
+    const sessions: LiveSessionInfo[] = [
+      live({ id: 'a', status: 'idle', lastOutputAt: 5000 }), // finished (5000 > 100)
+      live({ id: 'b', status: 'waiting' }), // needsInput
+      live({ id: 'c', status: 'stuck' }), // stuck
+      live({ id: 'd', status: 'working' }), // working
+      live({ id: 'e', status: 'idle', lastOutputAt: 50 }), // idle but stale (50 < 100) → not finished
+    ]
+    const d = buildDigest(sessions, 100)
+    expect(d.total).toBe(5)
+    expect(d.finished).toBe(1)
+    expect(d.needsInput).toBe(1)
+    expect(d.stuck).toBe(1)
+    expect(d.working).toBe(1)
+  })
+
+  it('does not count an idle session with no lastOutputAt as finished', () => {
+    const d = buildDigest([live({ id: 'a', status: 'idle' })], 0)
+    expect(d.finished).toBe(0)
+  })
+
+  it('treats a future `since` as "nothing new" (0 finished)', () => {
+    const d = buildDigest([live({ id: 'a', status: 'idle', lastOutputAt: 1000 })], 999_999_999_999)
+    expect(d.finished).toBe(0)
+  })
+
+  it('sums telemetry.costUsd across sessions', () => {
+    const sessions: LiveSessionInfo[] = [
+      live({ id: 'a', status: 'idle', telemetry: { at: 1, costUsd: 1.5 } }),
+      live({ id: 'b', status: 'working', telemetry: { at: 1, costUsd: 2.25 } }),
+      live({ id: 'c', status: 'working' }), // no telemetry → contributes 0
+    ]
+    const d = buildDigest(sessions, 0)
+    expect(d.totalCostUsd).toBeCloseTo(3.75)
+  })
+
+  it('projects per-session flags + title (last cwd segment)', () => {
+    const d = buildDigest([live({ id: 'a', status: 'waiting', cwd: '/home/u/my-repo' })], 0)
+    const row = d.sessions[0]
+    expect(row?.id).toBe('a')
+    expect(row?.title).toBe('my-repo')
+    expect(row?.needsInput).toBe(true)
+    expect(row?.finished).toBe(false)
+    expect(row?.stuck).toBe(false)
+  })
+
+  it('clamps a bad `since` to 0', () => {
+    const d = buildDigest([], NaN as unknown as number)
+    expect(d.since).toBe(0)
+  })
+})