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name: yao-daemon description: "Daemon process management — start, monitor, restart, stop long-running services. ALWAYS invoke this skill when the user asks to start, check, restart, or stop background services, dev servers, or daemon processes."

Daemon Management

Tools

• yao_daemon_start — Start a long-running service. Always runs in background; returns daemon_id immediately.
• yao_daemon_list — List daemons. Supports --status filter and --limit/--offset pagination.
• yao_daemon_status — Get full details for a daemon (daemon_port, daemon_url, started_at, daemon_restarts).
• yao_daemon_stop — Stop a running daemon.
• yao_daemon_restart — Restart a daemon (preserves the same ID, increments daemon_restarts).
• yao_job_output — Read daemon output (pass daemon_id as job_id).

Parameters

yao_daemon_start

| Param | Required | Default | Description | |-------|----------|---------|-------------| | command | yes | — | Shell command to execute | | description | yes | — | Concise 5–10 word summary | | port | no | auto-detect | Expected listen port; the system verifies the port is ready before reporting it | | args | no | — | Additional arguments | | working_dir | no | workspace | Working directory |

yao_daemon_list

| Param | Default | Description | |-------|---------|-------------| | status | all | Filter: running, stopping, completed, failed, cancelled, port_detecting, all | | limit | 20 | Max items per page | | offset | 0 | Skip first N items |

yao_daemon_restart / yao_daemon_status / yao_daemon_stop

| Param | Required | Description | |-------|----------|-------------| | daemon_id | yes | The daemon ID |

Response Fields

All responses are JSON. Daemon objects contain:

id, kind, session_id, status, description,
command, command_argv, command_line, pid, pgid, user,
started_at, finished_at, duration_ms, exit_code, signal, detail,
daemon_port, daemon_url, daemon_restarts, seq

• daemon_port — The verified listen port (0 if not yet detected or not specified).
• daemon_url — http://localhost:<port> (empty until port is verified as listening by the daemon's own process tree).
• daemon_restarts — Number of restarts via yao_daemon_restart.
• started_at — Unix millisecond timestamp of the most recent start.

Port detection behavior:

Both modes start by returning port_detecting with daemon_port: 0 if the port is not confirmed within the initial ~2s settle window. If the port is confirmed within ~2s, start returns running with daemon_port/daemon_url directly.

• --port N (explicit): Verifies port N is listening AND owned by this daemon's process tree. If not confirmed within ~2s, returns status: "port_detecting". Poll yao_daemon_status until status changes to running — either with daemon_port: N and daemon_url (port confirmed), or with daemon_port: 0 and detail: "specified port N not detected within timeout" (~60s).
• No --port (auto-detect): Scans the daemon's process tree for any listening TCP port. If not found within ~2s, returns status: "port_detecting". The scan continues in background (~60s); if a port is found, status changes to running with daemon_port/daemon_url and a <BackgroundJobReceipt> is delivered. If no port is found after ~60s, status changes to running with daemon_port: 0.

List (paginated)

{ "daemons": [...], "total": 5, "offset": 0, "limit": 20, "has_more": false }

Stop (already terminal)

{ "job": { ... }, "detail": "already in terminal state (cancelled); no action taken" }

Errors

Structured JSON with code and message:

{ "error": { "code": "not_found", "message": "daemon \"dmn_xxx\" not found" } }

Codes: invalid_argument, not_found, internal.

Usage Rules

1. Always provide a description.
2. Specify port when starting a server — the system confirms the port is actually listening before reporting daemon_url.
3. Daemons run indefinitely — use yao_daemon_stop to terminate.
4. Use yao_daemon_restart to restart a crashed or misconfigured daemon without losing its ID.
5. Monitor output with yao_job_output passing the daemon_id as job_id.

BackgroundJobReceipt

When a daemon's port becomes ready, the system delivers a <BackgroundJobReceipt> XML message containing the daemon_url. Use that URL for subsequent HTTP requests to the daemon.