[BUG] Bottom toolbar conflates agents from multiple Claude Code sessions on the same machine

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

TITLE
Bottom toolbar conflates agents from multiple Claude Code sessions on the same machine

BEHAVIOR
When multiple Claude Code sessions run on the same machine (un-sandboxed shared
filesystem), the bottom toolbar in any session shows ALL agent processes across
ALL sessions on the machine — not just the agents owned by the current session.

EVIDENCE FROM A REAL OCCURRENCE THAT TRIGGERED THIS REPORT

• Session A torn down its full team (TeamDelete returned success; all 6 agents

individually confirmed shutdown_approved + teammate_terminated).

• Toolbar still showed ~21 active agents.
• ps -ef | grep team-name confirmed those 21 agents belonged to two OTHER

Claude Code sessions running on the same machine (different parent PIDs,
different team names, different working directories).

• Session A's own agent count via process inspection: 0 (correctly torn down).
• The user's mental model — "the toolbar reflects my session" — was violated.

What Should Happen?

EXPECTED BEHAVIOR

• Default: toolbar shows only agents whose --parent-session-id matches the

current session's UUID.

• Add an opt-in toggle (e.g., a setting or status-line indicator) for users

who want machine-wide visibility across all their concurrent sessions.

WHY THIS MATTERS

• Misleading after teardown — successful teardowns appear to have failed.
• Misleading during dispatch — a user in session A trying to count their own

spawned agents sees noise from sessions B/C/D.

• Multi-session usage is common: one session per worktree, one per repo, one

per parallel feature task. Not an edge case.

• Especially impactful for plugins that orchestrate many concurrent agents

(15+ per session is realistic), where cross-session noise dominates the
toolbar and obscures the actual session state.

FIXABILITY
The data needed to filter is already present in the agent process arguments —
each agent process is launched with --parent-session-id <UUID> (visible via
ps). The toolbar renderer just needs to filter the agent list by current
session's UUID before display. No new state to capture.

ENVIRONMENT

• Claude Code version: 2.1.121
• OS: Darwin 25.4.0
• Shell: zsh
• Backend: Vertex AI (also reproducible on Anthropic API per user reports)
• Trigger context: heavy multi-agent plugin (15+ concurrent agents per

session); the bug applies to ANY multi-session use of the Agent tool, the
plugin just makes it more visible by virtue of agent count.

Error Messages/Logs

Steps to Reproduce

REPRO

1. Open Claude Code session A. Spawn N agents via the Agent tool / TeamCreate.
2. Open Claude Code session B (separate terminal, same machine). Spawn agents

in B too via its own Agent tool / TeamCreate.

1. In either session, observe the toolbar — it shows the union of agents from

both sessions, with no visual indication of which agents belong to which.

1. In session A, fully tear down its agents (TeamDelete + per-agent

shutdown_request → confirmed shutdown_approved → teammate_terminated for
every agent).

1. Session A's toolbar STILL shows session B's agents (which are correctly

running there) — and the user reads this as "my teardown didn't work,"
because the toolbar gives no signal that those remaining entries belong to
another session entirely.

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

❯ claude --version 2.1.128 (Claude Code)

Platform

Google Vertex AI

Operating System

macOS

Terminal/Shell

iTerm2

Additional Information

_No response_