[FEATURE] Mods: let a mod see agents that run outside the lead's process (pane teammates, remote agents)

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet (closest: #100918, workflow agents)
• [x] This is a single feature request (not multiple features)

Problem Statement

Mods cannot see agents that run outside the lead's process. In 2.1.296:

• AgentInfo has no tool count or activity time.
• "A teammate in a terminal pane of its own runs no loop here". Its status comes from "what it last wrote in its team's roster ... a pane that is closed or dies leaves that word standing."
• For a pane teammate, $.session.messages({ agentId }) returns SessionMessagesDeny: "the agent runs in another process (a pane-hosted teammate)".
• A remote agent (isolation: 'remote') raises no tool.call in the lead.
• A message between two pane teammates raises no session.receive in the lead.

So a mod cannot tell a busy remote agent or pane teammate from a stalled one.

Proposed Solution

1. Add to AgentInfo: location: 'process' | 'pane' | 'remote', toolCount?, lastActivityAt?, and statusAt? (when status was last reported). List remote agents in $.agent.list().
2. In the lead, raise an observe-only session.receive for a mailbox message between two pane teammates, with origin.teammate as the sender and agentId as the receiver's address.

Alternative Solutions

• Let $.session.messages({ agentId }) read a pane teammate's saved transcript. This covers messages, not liveness.
• Read the team's inbox files. The format is undocumented.

Priority

Medium - Would be very helpful

Feature Category

Developer tools/SDK

Use Case Example

1. Downrange (github.com/dot-agi/downrange) shows each background agent's tool count and flags quiet after 2 minutes of silence.
2. A remote subagent or a tmux-pane teammate shows 0 tools and quiet while it works. Item 1 fixes that.
3. High Command (github.com/dot-agi/high-command) "does not see messages between teammates that run in their own split panes". Item 2 fixes that.

Additional Context

Claude Code 2.1.296, macOS. Quotes are from the mod index.d.ts that 2.1.296 writes. Related: #98657, #87415.