feat(core): AgentWork primitive + heartbeat STATUS protocol replacement

[luokerenx4]

Summary

Three architectural changes that landed together because they're
load-bearing on each other:

1. Introduces AgentWork core primitive — the missing abstraction
   for "Alice does an async task outside chat". Three trigger sources
   today (heartbeat / cron / task-router) and any future ones plug
   into the same shape: payload + work + gates + emit.
2. Adds notify_user tool — Alice's structured way to signal
   "deliver this to the user" intent during autonomous work, replacing
   the legacy STATUS: HEARTBEAT_OK | CHAT_YES + CONTENT: ... regex
   protocol that heartbeat used.
3. Migrates all three trigger sources to the new primitive. The
   STATUS regex parser dies, copy-paste between cron and task-router
   collapses, heartbeat persona prompt rewritten to teach the tool.

The payload + work shape was identified in conversation — heartbeat
/ cron / task-router are isomorphic at the abstraction level (same
trigger → AI → notify → emit pipeline, only labels differ); they
just lacked a primitive to share.

Per-session contributions

2026-05-10 — AgentWork + notify_user

• New: src/core/agent-work.ts (~250 lines) — AgentWorkRunner class
  with input/output gates, error handling, emit fan-out
• New: src/core/agent-work.spec.ts (37 tests) — gate combinations,
  error paths, tool-call observation, hook misbehaviour, concurrent runs
• New: src/tool/notify-user.ts — intent-signal tool, no side-effects
  (runner-side outputGate handles dedup + delivery)
• Modified: src/ai-providers/types.ts — ProviderResult.toolCalls
  optional field (additive)
• Modified: src/core/agent-center.ts — accumulates tool_use events,
  packages into final done event
• Rewritten: src/task/heartbeat/heartbeat.ts (410 → 290 lines) —
  parseHeartbeatResponse deleted; default persona prompt rewritten
  to teach notify_user; active-hours becomes inputGate; dedup +
  notify_user inspection becomes outputGate
• Rewritten: src/task/heartbeat/heartbeat.spec.ts — 28 tests
  (was 35; 10 STATUS-regex tests deleted with the function)
• Thinned: src/task/cron/listener.ts (135 → 110 lines)
• Thinned: src/task/task-router/listener.ts (122 → 100 lines)
• Wired in src/main.ts: AgentWorkRunner constructed once, shared
  across all three listeners; notify_user registered in ToolCenter
• Key commits: c7d011d, 014b844, b857d7a

Full commit log

b857d7a refactor(task): migrate heartbeat / cron / task-router to AgentWorkRunner
014b844 feat(tool): add notify_user — intent signal for autonomous notifications
c7d011d feat(core): AgentWork primitive + ProviderResult.toolCalls plumbing

Test plan

• npx tsc --noEmit clean
• pnpm test — 1622 / 1622 passing (+30 net: 37 new agent-work, +-7 heartbeat after STATUS deletion + notify_user-based rewrite)
• vite build clean
• pnpm build clean
• Manual (required — this changes Alice's notification protocol;
  AI-portfolio-intuition memory note flags this category for
  careful visual verification):
  • Trigger heartbeat manually (runNow on __heartbeat__ job).
    Verify Alice either calls notify_user (notification appears in
    inbox + connectors) or stays silent (skip emit, no notification).
  • Trigger heartbeat outside active-hours config — verify skip
    event with reason: 'outside-active-hours' and AI never invoked.
  • Two heartbeat fires with same notify_user text within window —
    verify second is skipped with reason: 'duplicate'.
  • Run a user-defined cron job — verify notification shows up just
    as before (cron behaviour unchanged).
  • Send a task.requested webhook — verify notification just as
    before (task-router behaviour unchanged).
  • Verify parseHeartbeatResponse is gone:
    git grep parseHeartbeatResponse returns nothing.
  • Verify STATUS regex is gone:
    git grep "STATUS:.*HEARTBEAT_OK" returns nothing in src/.

Out of scope (deferred)

• Workspace primitive (VS Code-style directory + state per
  long-running async task) — discussed extensively; the right
  long-term shape but too disruptive for this PR. AgentWork is
  structurally compatible.
• i18n for AI output — addressed per-prompt at instruction time;
  no system-level i18n introduced.
• task-router renaming — task.requested event + module name
  kept as-is; semantic is "router that submits webhook events as
  AgentWork".
• cron / task-router prompt changes — defaults unchanged; AI in
  those sessions still doesn't reference notify_user, so behaviour
  is identical to before this PR.

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