[ignaciomella]

Problem

apply_pane_style / reset_pane_style (and the inline resets in pane-focus-in.sh / reset_all.sh) tint pane backgrounds with select-pane -t <pane> -P "bg=…". select-pane with -P still makes the target pane the active pane (verified on tmux 3.6a), so any agent state change that styles a non-active pane also moves focus.

The capture/restore added in 01b363c mitigates this but can't eliminate it:

• it races with the user — switching panes between the capture and the restore snaps focus back to the stale captured pane;
• when the script runs without a client context (e.g. from agent hooks), tmux display-message -p '#{pane_id}' can resolve a different pane than the one the attached client is on, so the restore itself moves the user's focus.

In practice, when working in a window that shares panes with running agents (a common grid layout), focus gets randomly yanked to another pane whenever an agent changes state.

Fix

Write the style through the pane-scoped window-style option instead:

tmux set-option -p -t "$pane_id" window-style "bg=…"

This sets the same style (select-pane -P is implemented on top of the same pane option) but has no focus side effect, so the capture/restore dance can be dropped entirely. Pane-scoped options need tmux ≥ 3.1, so this PR updates the README minimum from 3.0 to 3.1.

Verification

• Added tests/test-pane-style-preserves-focus.sh to verify styling and reset preserve the active pane and window_zoomed_flag while applying the expected background to an inactive pane.
• bash -n agent-indicator.tmux scripts/*.sh install.sh setup.sh tests/*.sh tests/lib/*.sh
• shellcheck -x -S warning agent-indicator.tmux scripts/*.sh install.sh setup.sh tests/*.sh tests/lib/*.sh
• python3 -m py_compile scripts/agent-limits.py
• ./tests/run-all.sh

🤖 Generated with Claude Code

[hammondr]

Independently reached the same fix on tmux 3.7b before finding this PR, and can confirm both the diagnosis and the resolution.

One consequence worth adding to the record: on 3.7b, select-pane -t <pane> -P "bg=..." against a non-active pane not only moves the active pane, it also clears the window zoomed flag. So in a zoomed layout, any background agent reaching needs-input or done unzooms the user's current view in addition to stealing focus. set-option -p -t <pane> window-style "bg=..." sets the same background with neither side effect.

Reproduction (tmux 3.7b), starting from a zoomed 2-pane window:

zoom pane %42 (active)               -> window_zoomed_flag=1  active=%42
select-pane -t %43 -P "bg=colour52"  -> window_zoomed_flag=0  active=%43
set-option -p -t %43 window-style "bg=colour52" (from zoom) -> window_zoomed_flag=1  active=%42

Verified end to end: a background pane transitioning to done while another pane is zoomed keeps both the zoom and the active pane, tints the background pane, and clears the tint on focus. +1 to merging this.

[accessd]

So in a zoomed layout, any background agent reaching needs-input or done unzooms the user's current view in addition to stealing focus.

I've been struggled with this too! Nice to have the fix!