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+# Reset tmux window indexes
+
+**Date:** 2026-06-11
+**Status:** Approved
+
+## Goal
+
+Add reusable functionality that compacts tmux window indexes inside the `hqt`
+tmux session so keyboard shortcuts such as `Alt+1`, `Alt+2`, and `Alt+3` stay
+useful after windows have been closed.
+
+This reset affects only tmux window indexes. It does not change database session
+IDs, `tmux_session_name`, harness conversation IDs, nicknames, panes, or running
+processes.
+
+## Behavior
+
+The reset operation works on the configured `hqt` tmux session:
+
+- The home/TUI window always ends at tmux index `0`.
+- Every non-home window keeps its current name, pane, process, and content.
+- Non-home windows are sorted by their current tmux index.
+- Those non-home windows are moved into contiguous indexes starting at `1`.
+
+Example:
+
+```text
+0: ⌂ HQT
+1: hqt-foo
+4: hqt-bar
+9: hqt-baz
+```
+
+becomes:
+
+```text
+0: ⌂ HQT
+1: hqt-foo
+2: hqt-bar
+3: hqt-baz
+```
+
+If the home window is not already at `0`, it is moved to `0` first, then the
+remaining windows are compacted after it in their original index order.
+
+## Architecture
+
+Add the reset at the tmux layer rather than the session or database layer.
+Existing app and service code targets windows by name, so changing tmux indexes
+should not disturb attach, stop, delete, status polling, or label syncing.
+
+### Runner
+
+Add a low-level method on `TmuxRunner`, for example:
+
+```python
+async def reset_window_indexes(self, home_window: str) -> bool:
+    ...
+```
+
+The method should:
+
+1. List windows for `self.session_name` with `#{window_id}`,
+   `#{window_index}`, and `#{window_name}`.
+2. Find the row whose name matches `home_window`.
+3. Move the home window to index `0` if needed.
+4. Sort all other windows by their original index.
+5. Move each non-home window to `1..N` in that order.
+
+Use `move-window` with `window_id` as the source target so changing one index
+cannot make a later move target the wrong window. The destination should target
+the configured tmux session and explicit index.
+
+The implementation should be idempotent: running it against an already compact
+session should return success without changing anything meaningful.
+
+### Manager
+
+Add a thin delegate on `TmuxManager`, for example:
+
+```python
+async def reset_window_indexes(self, home_window: str) -> bool:
+    return await self.runner.reset_window_indexes(home_window)
+```
+
+No `SessionService` change is needed for the initial implementation. This is a
+tmux maintenance operation, not a session lifecycle operation.
+
+### Command Surface
+
+Implement the reusable operation now and defer user-facing wiring. A command
+palette is planned separately, so this feature should expose a callable method
+that the future command can invoke.
+
+Do not add a TUI keybinding or footer item in this change.
+
+## Error Handling
+
+- If the configured tmux session does not exist or cannot be listed, return
+  failure and leave the database untouched.
+- If the home window is missing, return failure rather than guessing which
+  window should become index `0`.
+- If a `move-window` command fails, return failure. The operation may have
+  partially moved tmux windows before the failure; this is acceptable because
+  tmux indexes are maintenance metadata and no persisted hqt state is changed.
+- Log tmux stderr for failed operations to aid debugging.
+
+## Testing
+
+Add focused tests in `tests/test_tmux.py`:
+
+- Missing home window returns failure and performs no moves.
+- Already compact windows return success.
+- Sparse indexes compact in current index order:
+  `0 home, 1 foo, 4 bar, 9 baz` moves `bar` to `2` and `baz` to `3`.
+- Home initially not at `0` is moved to `0`, and all other windows compact to
+  `1..N` in original order.
+- Moves target stable window identities, not mutable index-only targets.
+
+The implementation must pass the project checks after code changes:
+
+```bash
+uv run ruff format src tests
+uv run ruff check src tests
+uv run ty check
+```
+
+## Out of Scope
+
+- Changing database primary keys.
+- Changing `Session.tmux_session_name`.
+- Changing harness session IDs or resume behavior.
+- Adding command palette UI, keybindings, or footer labels.
+- Enabling permanent tmux automatic renumbering.