feat: 3 additional events, session_started, user_message, client_connected

[grota]

Summary

Adds three new configurable event types and improves subagent detection performance by introducing in-memory session tracking.

New events

Event type	Trigger	Default
session_started	A new top-level (non-subagent) session is opened (session.created)	sound only
user_message	The user submits a message in a top-level session (message.updated, role=user)	sound only
client_connected	The OpenCode plugin finishes initializing and is ready	sound only

All three default to sound enabled, notification disabled to avoid notification spam for high-frequency or low-urgency events. Users can override each individually in opencode-notifier.json.

Note on client_connected

There is no SDK event that reliably signals client connection from a plugin's perspective. The implementation fires the event via a short setTimeout after plugin startup, which is the closest available approximation. Config is read at fire-time (not schedule-time) so user overrides are respected, and the timeout only runs after the desktop-client guard has already passed.

In-memory subagent tracking

Previously, every session.idle event required an API call (client.session.get) to determine whether the session was a subagent (by checking parentID). This PR introduces a module-level subagentSessionIds: Set<string> populated from session.created, session.updated, and session.deleted events.

• Fast path: if a session ID is already known to be a subagent, processSessionIdle returns immediately without any API call.
• Fallback: sessions not yet seen in the Set still go through the API call, and if confirmed as a subagent, are added to the Set for future events.
• The Set is pruned during the existing 5-minute cleanup interval alongside the other per-session maps.

Configuration

The three new events are fully configurable like all existing events:

{
  "events": {
    "session_started": { "sound": true, "notification": false, "command": true },
    "user_message": { "sound": false, "notification": false, "command": false },
    "client_connected": { "sound": true, "notification": true, "command": false }
  },
  "messages": {
    "session_started": "Session started: {sessionTitle}",
    "user_message": "User sent a message: {sessionTitle}",
    "client_connected": "OpenCode connected"
  },
  "sounds": {
    "session_started": "/path/to/custom.wav",
    "user_message": null,
    "client_connected": null
  },
  "volumes": {
    "session_started": 0.5,
    "user_message": 0.3,
    "client_connected": 1.0
  }
}

Changes

• src/config.ts: Added session_started, user_message, and client_connected to EventType, NotifierConfig, DEFAULT_CONFIG, and loadConfig().
• src/index.ts:
  • Added subagentSessionIds: Set<string> for in-memory subagent tracking.
  • Handle session.created: register subagent IDs; fire session_started for top-level sessions.
  • Handle session.updated / session.deleted: keep the subagent Set accurate.
  • Handle message.updated: fire user_message when role === "user" for non-subagent sessions.
  • Fire client_connected via setTimeout after plugin initialization (inside the desktop-client guard).
  • Updated processSessionIdle to use the fast path before falling back to the API.

Tests

All 43 tests pass. No new test failures introduced.