Claude Code pane reports `working` while idle at the prompt with a background shell running

Is this a reproducible bug?

• I confirm this is a reproducible bug, not a feature request, idea, question, contribution proposal, or direction check.
• I reproduced this bug on the version and environment reported below using the exact steps provided.

Current behavior

A Claude Code pane sitting at an empty ❯ prompt reports agent_status: working if it has a background shell running. herdr agent explain shows background_shell_working (priority 965, manifest 2026.08.29.1) matching on the footer's · 1 shell ·, beating live_prompt_box (idle, 950).

Expected behavior

An idle prompt box should report idle. A background shell can outlive the turn that started it, so its presence doesn't mean the agent is in a turn.

Some examples:

• Running a background server
• Opening a file in a new tab in Neovim so the user can edit it.

Reproduction

1. Start Claude Code in a Herdr pane.
2. Ask it to run a long command as a background shell, such as sleep 300 with run_in_background, so that the footer shows · 1 shell ·.
3. Wait for the turn to finish, so the agent is sitting at its prompt with nothing to do.
4. Run herdr pane get <pane>, which reports agent_status: working instead of idle.

Impact

This change means that I can't distinguish between an agent that's genuinely done work and one that's simply running a background task.

Environment

• Herdr version: 0.8.2 (Homebrew)
• Update channel (stable or preview): stable
• Operating system: macOS 26.6.2 (arm64)
• Terminal: Ghostty
• Shell, if relevant: zsh
• Relevant config, if any: Claude Code 2.1.251; Claude detection manifest 2026.08.29.1 (remote)