feat(mvp): Phase 1 control layer + API vertical slice

Implements the Phase 1 MVP from the README: a stateless control layer + HTTP
API over a centralized database, with hook-enforced test/push gates.

- DB layer: SQLAlchemy Core, one schema rendering both Postgres (BIGSERIAL /
  TIMESTAMPTZ / JSONB) and SQLite (INTEGER PK / TEXT / JSON) via portable types;
  native ON CONFLICT DO UPDATE checkmark upsert on both dialects.
- Alembic dual-dialect migrations (render_as_batch for SQLite); tests run a real
  `alembic upgrade head`.
- FastAPI: projects/agents/checkmark/log/answer/resume + shared log/context
  routes, single global bearer token, higher-trust token gating shared-context
  writes, project isolation on every route.
- Hooks (`python -m handler.hooks <event>`): Stop test gate (block on red),
  PreToolUse AskUserQuestion defer + `git push` gate (tests then throwaway
  build), Notification generic webhook (no-op without WEBHOOK_URL). Identity via
  env injected at spawn; verify is the mock seam.
- Control CLI: spawn/list/attach/kill, hard `.mise.toml [tasks.test]` gate,
  generated per-agent settings.json, identity + DATABASE_URL injected via tmux;
  tmux is the mock seam.
- 45 tests (SQLite), ruff clean. Live claude/tmux/mise spawning deferred behind
  the mocked seams.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01W5ZuS5pV1NS6eKsRZHXonY

tests/test_api_projects_agents.py

@@ -0,0 +1,64 @@
+"""Project + agent routes, and project isolation (README 3.4)."""
+
+from __future__ import annotations
+
+
+def _mk_project(client, auth, pid="proj", root="/tmp/proj"):
+    return client.post("/projects", json={"id": pid, "root_dir": root}, headers=auth)
+
+
+def test_create_and_list_project(client, auth):
+    r = _mk_project(client, auth)
+    assert r.status_code == 201
+    assert r.json()["id"] == "proj"
+    listing = client.get("/projects", headers=auth).json()
+    assert [p["id"] for p in listing] == ["proj"]
+
+
+def test_duplicate_project_conflicts(client, auth):
+    _mk_project(client, auth)
+    assert _mk_project(client, auth).status_code == 409
+
+
+def test_create_and_list_agent(client, auth):
+    _mk_project(client, auth)
+    r = client.post(
+        "/projects/proj/agents",
+        json={"name": "api", "working_dir": "/tmp/proj/api"},
+        headers=auth,
+    )
+    assert r.status_code == 201
+    agents = client.get("/projects/proj/agents", headers=auth).json()
+    assert [a["name"] for a in agents] == ["api"]
+
+
+def test_agent_under_missing_project_is_404(client, auth):
+    r = client.get("/projects/ghost/agents", headers=auth)
+    assert r.status_code == 404
+
+
+def test_project_isolation_same_agent_name(client, auth):
+    # Two projects can each have an agent named "api"; neither leaks into the other.
+    _mk_project(client, auth, "a", "/tmp/a")
+    _mk_project(client, auth, "b", "/tmp/b")
+    client.post(
+        "/projects/a/agents",
+        json={"name": "api", "working_dir": "/tmp/a/api"},
+        headers=auth,
+    )
+    a_agents = client.get("/projects/a/agents", headers=auth).json()
+    b_agents = client.get("/projects/b/agents", headers=auth).json()
+    assert [x["name"] for x in a_agents] == ["api"]
+    assert b_agents == []
+    # The agent is invisible under project b.
+    assert client.get("/projects/b/agents/api/checkmark", headers=auth).status_code == 404
+
+
+def test_checkmark_404_before_any_checkpoint(client, auth):
+    _mk_project(client, auth)
+    client.post(
+        "/projects/proj/agents",
+        json={"name": "api", "working_dir": "/tmp/proj/api"},
+        headers=auth,
+    )
+    assert client.get("/projects/proj/agents/api/checkmark", headers=auth).status_code == 404