Subagent Watcher

The Subagent Watcher provides real-time monitoring of sub-agents spawned by your primary AI agents. AgentMux offers two complementary views: the Swarm pane for overview and the Subagent pane for focused inspection.

Swarm Pane

The Swarm pane is the bird’s-eye view of all agent activity. Open it from the top bar (bee icon) or right-click a pane header and select Swarm.

Overview Tab

Shows all sub-agents across your workspace, split into:

Active Subagents — Currently running, with event count and last activity time
Completed Subagents — Finished sessions

Each entry shows:

Field	Description
Agent ID	Unique identifier (truncated)
Slug	Human-readable name
Parent Agent	Which agent spawned this sub-agent
Status	`active` or `completed`
Event Count	Number of events recorded
Model	AI model being used

Click any sub-agent to open a dedicated Subagent pane for that agent.

History Tab

Browse past agent sessions with metadata:

Field	Description
Session ID	Unique session identifier
Provider / Model	AI provider and model used
Slug	Session name
Working Directory	Project path
Git Branch	Branch at time of session
Message Count	Total messages exchanged
Token Usage	Total tokens consumed
Created / Modified	Session timestamps

Search Tab

Full-text search across all agent sessions. Results include:

Agent ID and session
Timestamp and event type
Content preview
Relevance score

Subagent Pane

A focused view of a single sub-agent’s activity stream. Open one by clicking a sub-agent in the Swarm overview, or programmatically.

The header displays:

Sub-agent slug and ID
Status badge (active, completed, loading)
Event count
Last activity timestamp
Model name

Event Stream

Events are displayed in chronological order:

Event Type	Display
Text	Agent text output
Tool Use	Tool name and input summary
Tool Result	Success/error indicator with result preview
Progress	Progress output from long-running operations

Auto-Scroll

The Subagent pane auto-scrolls to follow new events. Scrolling up pauses auto-scroll and shows a “scroll to bottom” button. Scrolling to the bottom re-enables auto-scroll.

How It Works

When an agent session starts, the backend begins tracking its JSONL output stream
Sub-agents spawned by the parent agent are detected from the stream
The backend emits subagent events via the pub-sub system
The Swarm pane subscribes to all subagent events for the overview
Individual Subagent panes subscribe to events for a specific agent ID

Data is persisted in JSONL files on disk, allowing history browsing even after sessions complete.