Summary

This PR adds proper support for the label parameter in sessions_spawn:

• Persist the label in the session store
• Expose it in sessions.list response
• Display it in the web UI sessions table
• Allow sessions_send to find sessions by label

Motivation

The label parameter existed in sessions_spawn but was never actually persisted - it was a "phantom parameter". This PR makes it functional, enabling users to:

1. Identify sub-agents by human-readable names instead of UUIDs
2. Reconnect to sub-agents using their label via sessions_send

Changes

Core Feature

• sessions.patch: Accept and store label field
• sessions.list: Return label in session entries
• sessions_spawn: Pass label through registry → announce flow → patch
• sessions_send: New optional label param for lookup (alternative to sessionKey)

UI

• Add "Label" column to sessions table in web UI

Safety Improvement

• Session store writes now merge with existing entries ({ ...existing, ...new })
• Prevents accidental loss of fields like label during concurrent writes

Architecture Note

We initially attempted to persist the label "properly" by passing it through the agent call and storing it during session initialization. However, the auto-reply flow has multiple session write points that overwrite entries, and making them all merge-aware proved unreliable.

Working solution: Patch the label in the finally block of runSubagentAnnounceFlow, after all other writes complete. This is a workaround but robust.

A future refactor could make all session writes consistently merge-based, enabling the cleaner approach.

Usage

// Spawn with label
sessions_spawn({ task: "Implement feature X", label: "feature-x-worker" })

// Later, reconnect by label (no need to remember the UUID!)
sessions_send({ label: "feature-x-worker", message: "Continue with step 2" })

// View labels in sessions list
sessions_list({ activeMinutes: 60 })
// Returns: [{ key: "agent:main:subagent:abc...", label: "feature-x-worker", ... }]

Files Changed (20)

Core:

• src/config/sessions.ts - Add label to SessionEntry type
• src/gateway/protocol/schema.ts - Add label to schemas
• src/gateway/server-methods/sessions.ts - Handle label in patch
• src/gateway/session-utils.ts - Return label in list mapping
• src/agents/tools/sessions-spawn-tool.ts - Pass label to registry
• src/agents/subagent-registry.ts - Store and forward label
• src/agents/subagent-announce.ts - Patch label in finally
• src/agents/tools/sessions-send-tool.ts - Label lookup support

Safety (merge writes):

• src/auto-reply/reply/session.ts
• src/auto-reply/reply/agent-runner.ts
• src/auto-reply/reply/directive-handling.ts
• src/auto-reply/reply/model-selection.ts
• src/auto-reply/reply/session-updates.ts

UI:

• ui/src/ui/types.ts
• ui/src/ui/views/sessions.ts