feat: add crg-daemon multi-repo watch daemon

[imkarrer]

Summary

Adds a multi-repo watch daemon (crg-daemon) that spawns child processes (subprocess.Popen) each running code-review-graph watch for a configured repository. The daemon reads its configuration from a TOML file, monitors it for live changes, health-checks running watchers, and auto-restarts dead ones. No external dependencies (no tmux, no screen) — pure Python stdlib process management.

Motivation

The graph can go stale when changes occur outside agent-driven updates — manual edits, branch switches, rebases, or pulls from teammates. The daemon orchestrates watchers automatically across configured repos so the graph stays current without relying on hooks or manual rebuilds.

Related: #36, #59.

Changes

New files

File	Lines	Description
code_review_graph/daemon.py	~870	Core daemon: DaemonConfig/WatchRepo dataclasses, TOML load/save, ConfigWatcher, WatchDaemon (start/stop/reconcile/daemonize/health-check/run_forever), PID management, subprocess.Popen child process management with threading.Lock, persisted state file (daemon-state.json) for cross-process status queries
code_review_graph/daemon_cli.py	~330	Standalone crg-daemon argparse CLI with 7 subcommands: start, stop, restart, status, logs, add, remove; status reads persisted state to report live/dead watchers
tests/test_daemon.py	~790	39 tests covering config parsing, PID management, WatchDaemon lifecycle, health checking with auto-restart, reconciliation, state persistence, cross-process status reporting, and CLI handlers

Modified files

File	Description
code_review_graph/cli.py	Added daemon subparser group with 7 subcommands delegating to daemon_cli handlers; updated module docstring
pyproject.toml	Added crg-daemon entry point in [project.scripts]; added tomli conditional dependency for Python < 3.11
README.md	Added "Multi-repo daemon" to Features table, CLI reference, and new expandable details section
docs/COMMANDS.md	Added daemon CLI commands and standalone crg-daemon reference with config example
docs/ROADMAP.md	Added v2.2.0 section under Shipped

How it works

1. User defines repos in ~/.code-review-graph/watch.toml
2. crg-daemon start spawns one subprocess.Popen child per repo, each running code-review-graph watch with stdout/stderr redirected to per-repo log files
3. A background thread monitors watch.toml for changes and reconciles child processes (starts new repos, terminates removed ones)
4. Health checks run every 30 seconds — dead watchers (detected via proc.poll()) are automatically restarted
5. crg-daemon start (without --foreground) double-forks to daemonize, writing a PID file for lifecycle management
6. _terminate_child() sends SIGTERM, waits up to 5 seconds, then escalates to SIGKILL
7. Thread-safe access to _children: dict[str, Popen] via threading.Lock
8. Cross-process status: daemon persists child PIDs to daemon-state.json on every mutation; crg-daemon status reads this file and probes PIDs with os.kill(pid, 0) to report alive/dead without needing the daemon object in-memory

Usage

# Add repos
crg-daemon add ~/project-a --alias proj-a
crg-daemon add ~/project-b

# Start daemon
crg-daemon start

# Check status
crg-daemon status

# View logs
crg-daemon logs --repo proj-a -f

# Stop
crg-daemon stop

Also available as code-review-graph daemon start|stop|status|....

Testing

• 39 tests in tests/test_daemon.py
• All tests pass: uv run pytest tests/test_daemon.py -v
• Ruff: clean
• Mypy: no new errors (3 pre-existing unrelated issues in cli.py)

Checklist

• Feature branch from main
• Tests added for new functionality (39 tests)
• All tests pass (uv run pytest)
• Linting passes (uv run ruff check code_review_graph/)
• Documentation updated (README, COMMANDS.md, ROADMAP.md)
• No breaking changes to existing CLI or MCP tools
• No external dependencies (pure stdlib subprocess management)
• Code style: 100-char lines, Python 3.10+, from __future__ import annotations, type hints, logging.getLogger(__name__), no shell=True, parameterized SQL
• Cross-process status reporting via persisted state file