# MATE window switcher

Marco exposes the selected window title as a status-bar accessible. While Alt
is held, the old application can remain the X11 foreground client and the
switcher need not send a focus event. Ordinary foreground and editable-text
filters therefore cannot present its selection.

Following Orca's switcher event contract, Cthulhu reads the container name on
text insertion, selection change and showing-state gain. The accompanying
accessible-name signal does not repeat the announcement. The native adapter
handles this before routine background filtering and selected-child lookup.
It requires the `marco` process identity, the Marco application name, a known
visible/showing non-defunct status bar and a containing window on the same
provider bus. It refreshes only that accessible before reading the selection.

The application handler presents the title as transient speech and a Braille
message. It preserves application/native focus, browser mode and review
position, and rejects stale foreground epochs. Terminal handoff permits these
window-manager announcements; screen lock and internal UI still block them.
Normal key interruption and queued speech policy apply. No switcher state,
native references, timers or polling are retained. Other window managers are
outside this change.

## Automated checks

```sh
go test ./internal/app -run '^TestMateWindowSwitcher' -count=1
python3 tests/native_test_session.py env CTHULHU_NATIVE_WINDOW_SWITCHER=1 CTHULHU_NATIVE_BACKGROUND_EVENTS=1 go test -race ./internal/atspi -run '^TestNative(MateWindowSwitcherOutsideForeground|BackgroundEventFiltering)$' -count=1 -timeout=60s -v
```

The application regression reproduces the rejected non-focused status event
from the reported log, repeated forward/reverse selections, showing and
selection events, duplicate name rejection, stale/hidden/dead/impostor
rejection, terminal handoff, screen lock and Braille flash requests. A later
name change on the original control verifies that focus ownership survives.

The private GTK fixture publishes a non-focusable status bar with Marco's
application and process identity. It verifies that repeated insertions and a
showing event survive native background filtering while the editor retains
X11 foreground ownership. It models Marco's AT-SPI contract; it does not run
the real MATE window manager. The existing background flood test checks both
other-provider and same-provider inactive windows and zero content queries.
All native checks use a disposable X server and accessibility bus.

## Live acceptance

After reviewing the diff and starting the candidate through the normal local
launcher when ready:

1. Open at least three differently titled windows. Hold Alt and press Tab
   repeatedly. Confirm each selected title is spoken; repeat with Shift+Tab.
2. Release Alt and confirm normal reading follows the chosen application.
   Repeat from a terminal, and check that terminal delegation resumes.
3. Open the switcher, cycle through titles and press Escape. Confirm reading
   returns to the original control and review/navigation still work.
4. With a browser open, check heading navigation, address-bar editing and
   switching between two windows of the same application. Background status
   updates must stay quiet.
5. If using Braille, confirm each selection appears as a transient message
   and normal application content returns after dismissal. Switcher output
   must not appear while the screen is locked.

Physical keys, audible speech, real Marco cycling/cancellation and physical
Braille remain live acceptance checks. The original log contains an initial
status insertion but no later insertions for its subsequent Tab presses; keep
a fresh timed log if actual cycling still fails.