fix(cua-driver/linux): surface native Wayland windows in list_windows on GNOME/KDE (#1978)

[ai-ag2026]

Summary

list_windows returned no real application windows on GNOME/Mutter (and KDE/KWin) — only XWayland infrastructure. Native Wayland apps were invisible (#1978). This surfaces them via the AT-SPI registry.

Root cause

list_windows_dispatch gates the native-Wayland enumeration on is_wayland(), which requires DISPLAY unset. GNOME/KDE always run XWayland → DISPLAY set → is_wayland() false → it goes straight to X11 enumeration, which only sees XWayland apps. Native Wayland apps have no X11 XID, so they never appear.

Change

On an opted-in Wayland session (CUA_DRIVER_RS_ENABLE_WAYLAND=1 + WAYLAND_DISPLAY), merge the AT-SPI registry (keyed by pid — the same tree get_window_state walks) into the X11 results:

• X11 entries keep priority (real XID + geometry).
• AT-SPI adds windows for pids X11 didn't report (native Wayland apps that expose accessibility).

No change on pure-wlroots sessions (the existing is_wayland() path) or non-opted-in sessions.

Validation (Ubuntu 26.04, Mutter, Wayland)

• Before: list_windows returns only mutter guard window, GNOME Shell, mutter-x11-frames, ibus-* — no real apps.
• After: a native gnome-text-editor (no X11 XID) appears with its pid + title (New Document (Draft) - Text Editor), alongside the XWayland windows.

Limitations

Only apps that expose an AT-SPI accessibility tree are enumerable this way (the same constraint as get_window_state). AT-SPI windows carry a stable synthetic xid + pid but no geometry (x/y/size are 0), consistent with the existing AT-SPI fallback used on wlroots. Full native-Wayland geometry needs a compositor-side helper (out of scope).

Refs

Part of the #1922 native-Wayland follow-ups. Complements #2112 (input) — you can now both enumerate and drive native Wayland apps on GNOME/KDE.

Summary by CodeRabbit

• Bug Fixes
  • Improved window listing on Wayland by combining information from multiple sources when available.
  • Reduced missing or duplicate windows in mixed Wayland/X11 sessions by merging results more intelligently.

[coderabbitai]

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📝 Walkthrough

Walkthrough

The Wayland fallback path in list_windows_dispatch now merges window lists from X11 enumeration and the AT-SPI registry instead of returning X11 results alone. It always collects X11 windows, then conditionally appends AT-SPI windows whose pids weren't already present, when native Wayland is enabled and WAYLAND_DISPLAY is set.

Changes

Wayland Fallback Enumeration

Layer / File(s)	Summary
Merge AT-SPI windows into X11 fallback list libs/cua-driver/rust/crates/platform-linux/src/wayland/mod.rs	list_windows_dispatch's Wayland last-resort path now starts with X11 list_windows, then conditionally merges AT-SPI windows for pids not already reported by X11 when wayland_enabled() is true and WAYLAND_DISPLAY is set.

Estimated code review effort: 1 (Trivial) | ~5 minutes

Possibly related PRs

• trycua/cua#1998: Modifies AT-SPI tree walking retry behavior, directly affecting the AT-SPI-derived windows this fallback now enumerates.

Poem

A rabbit peeks through Wayland's veil,
X11's list, then AT-SPI's trail,
Pids unseen now hop right in,
No window left behind again!
🐇✨🪟

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly matches the main change: surfacing native Wayland windows in Linux list_windows on GNOME/KDE.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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[ai-ag2026]

Closing as superseded: the Linux convergence landing (#2182, commit 51a8e25) incorporated this fix verbatim — merge_atspi_windows, the already-covered skip of the redundant AT-SPI walk, and the documented merge caveats all ship on main as a strict superset (plus the ext_toplevel fallback and native-window enrichment beyond this branch). A rebase leaves an empty diff, so there is nothing left to merge. Thanks for folding the fix into the convergence series.