fix: review follow-ups — Arch default for at-spi fallback, input-backend degradation logging, test cleanups

.claude-plugin/marketplace.json

@@ -8,13 +8,13 @@
   },
   "metadata": {
     "description": "kwin-mcp marketplace \u2014 MCP server and skill for Linux KDE Plasma 6 Wayland desktop GUI automation (virtual sessions for headless testing, live sessions for real-desktop / container / kiosk control).",
-    "version": "0.8.1"
+    "version": "0.8.2"
   },
   "plugins": [
     {
       "name": "kwin-mcp",
       "source": "./integrations/claude-code",
-      "version": "0.8.1",
+      "version": "0.8.2",
       "description": "Bundles the kwin-mcp MCP server (uvx kwin-mcp) plus the kwin-desktop-automation skill that teaches session-mode selection, the observe-act-verify loop, US-QWERTY vs Unicode typing, and platform pitfalls (surface-local coordinates, QMenu invisibility, EIS edge limits, clipboard opt-in).",
       "category": "automation",
       "keywords": [

CHANGELOG.md

@@ -7,6 +7,17 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [0.8.2] - 2026-09-07
+
+### Fixed
+
+- The last-resort fallback of the at-spi-bus-launcher resolver returned `candidates[0]` (`/usr/libexec/...`, the Debian/Ubuntu/Fedora layout) when no candidate file existed and `shutil.which` found nothing — a dead path on Arch. The fallback is now the Arch default `/usr/lib/at-spi-bus-launcher`, and the resolved path is shell-quoted when embedded into the session's bash wrapper
+- The reason an `InputBackend` (KWin EIS) setup failed was silently swallowed when `session_start`/`session_connect` degraded to "no input backend"/ydotool; the exception text is now logged as a warning before the degradation (backend selection unchanged)
+
+### Internal
+
+- Test cleanups (dead assignment, tautological assert) and type hints on test fakes/helpers
+
 ## [0.8.1] - 2026-09-07
 
 ### Fixed

README.md

@@ -396,7 +396,7 @@ sudo apt install wl-clipboard wtype wayland-utils
 
 ## Installation
 
-> **Note**: the `kwin-mcp` name on PyPI tracks the upstream project (`isac322/kwin-mcp`, v0.7.0, MCP SDK 1.x). This repository is the actively maintained fork (v0.8.1, MCP SDK 2.x); install it from git or from a source checkout. The `uvx kwin-mcp` config examples in the [Configuration](#configuration) section resolve to the PyPI package.
+> **Note**: the `kwin-mcp` name on PyPI tracks the upstream project (`isac322/kwin-mcp`, v0.7.0, MCP SDK 1.x). This repository is the actively maintained fork (v0.8.2, MCP SDK 2.x); install it from git or from a source checkout. The `uvx kwin-mcp` config examples in the [Configuration](#configuration) section resolve to the PyPI package.
 
 ### Using uv (recommended)
 

integrations/claude-code/.claude-plugin/plugin.json

@@ -1,7 +1,7 @@
 {
   "$schema": "https://claude.ai/schemas/plugin.json",
   "name": "kwin-mcp",
-  "version": "0.8.1",
+  "version": "0.8.2",
   "description": "MCP server + skill for Linux KDE Plasma 6 Wayland GUI automation. Provides 30 MCP tools (mouse, keyboard, touch, clipboard, screenshot, AT-SPI2 accessibility tree, window mgmt, D-Bus passthrough) plus the kwin-desktop-automation skill that guides session-mode selection, observation/action sequencing, and platform pitfalls.",
   "author": {
     "name": "Byeonghoon Yoo",

integrations/opencode/plugin/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@isac322/kwin-mcp-opencode",
-  "version": "0.8.1",
+  "version": "0.8.2",
   "description": "OpenCode plugin for kwin-mcp \u2014 auto-registers the kwin-mcp MCP server (uvx kwin-mcp) and ships the kwin-desktop-automation skill on backend startup.",
   "type": "module",
   "main": "./dist/index.js",

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "kwin-mcp"
-version = "0.8.1"
+version = "0.8.2"
 description = "MCP server for Linux desktop GUI automation on KDE Plasma 6 Wayland — virtual testing and live desktop automation"
 readme = "README.md"
 license = "MIT"

src/kwin_mcp/core.py

@@ -7,6 +7,7 @@
 from __future__ import annotations
 
 import json
+import logging
 import os
 import shlex
 import shutil
@@ -24,6 +25,8 @@
 from kwin_mcp.screenshot import capture_frame_burst, capture_screenshot_to_file
 from kwin_mcp.session import LiveSession, Session, SessionConfig
 
+logger = logging.getLogger(__name__)
+
 # Install hints for external binaries
 _INSTALL_HINTS: dict[str, str] = {
     "wl-paste": (
@@ -246,7 +249,10 @@ def session_start(
         time.sleep(0.5)
         try:
             self._input = InputBackend(info.dbus_address)
-        except RuntimeError:
+        except RuntimeError as exc:
+            logger.warning(
+                "KWin EIS input backend unavailable, degrading to no input backend: %s", exc
+            )
             self._input = None
 
         input_status = "Input backend: KWin EIS" if self._input else "No input backend available"
@@ -306,7 +312,10 @@ def session_connect(
         try:
             self._input = InputBackend(dbus_addr)
             result += "\nInput backend: KWin EIS"
-        except RuntimeError:
+        except RuntimeError as exc:
+            logger.warning(
+                "KWin EIS input backend unavailable, falling back to ydotool if present: %s", exc
+            )
             self._input = None
             if shutil.which("ydotool"):
                 result += "\nInput backend: ydotool (EIS unavailable)"

src/kwin_mcp/session.py

@@ -10,6 +10,7 @@
 import contextlib
 import os
 import queue
+import shlex
 import shutil
 import signal
 import subprocess
@@ -29,13 +30,19 @@
     "/usr/lib/at-spi2-core/at-spi-bus-launcher",
 )
 
+# Last-resort default when no candidate exists and PATH lookup fails: the
+# Arch layout (the primary development platform). A literal rather than a
+# candidate index so reordering _AT_SPI_LAUNCHER_CANDIDATES cannot silently
+# repoint the fallback at another distro's path.
+_AT_SPI_LAUNCHER_FALLBACK = "/usr/lib/at-spi-bus-launcher"
+
 
 def _at_spi_bus_launcher() -> str:
     """Locate the AT-SPI bus launcher binary for the current distribution."""
     for candidate in _AT_SPI_LAUNCHER_CANDIDATES:
         if Path(candidate).exists():
             return candidate
-    return shutil.which("at-spi-bus-launcher") or _AT_SPI_LAUNCHER_CANDIDATES[0]
+    return shutil.which("at-spi-bus-launcher") or _AT_SPI_LAUNCHER_FALLBACK
 
 
 class SessionType(Enum):
@@ -400,7 +407,7 @@ def _build_wrapper_script(self, config: SessionConfig) -> str:
 # instead of dbus-broker (which reuses the host's AT-SPI bus).
 # The launcher path is distro-specific: resolved on the Python side
 # (_at_spi_bus_launcher) before this wrapper is assembled.
-{_at_spi_bus_launcher()} --launch-immediately &
+{shlex.quote(_at_spi_bus_launcher())} --launch-immediately &
 AT_SPI_PID=$!
 sleep 0.2
 

tests/test_input_eis_error.py

@@ -46,7 +46,9 @@ def test_setup_translates_dbus_exception_to_runtime_error() -> None:
     assert isinstance(caught.value.__cause__, dbus.DBusException)
 
 
-def test_setup_translates_connect_failure_from_interface_proxy(monkeypatch) -> None:
+def test_setup_translates_connect_failure_from_interface_proxy(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
     """A DBusException surfacing later (Interface/connectToEIS stage) is also
     translated: the whole dbus block is covered, not just get_object."""
 
@@ -59,7 +61,6 @@ def connectToEIS(self, *args: Any) -> None:  # noqa: N802
             raise dbus.DBusException("org.kde.KWin.EIS.RemoteDesktop: not supported")
 
     monkeypatch.setattr(input_module.dbus, "Interface", _ThrowingIface)
-    client = _client_with_bus(object())
 
     class _OkBus:
         def get_object(self, *args: Any, **kwargs: Any) -> object:

tests/test_screenshot_fallback.py

@@ -12,18 +12,23 @@
 
 from __future__ import annotations
 
+from typing import TYPE_CHECKING
+
 import dbus
 import pytest
 
+if TYPE_CHECKING:
+    from pathlib import Path
+
 import kwin_mcp.screenshot as screenshot_module
 from kwin_mcp.screenshot import capture_screenshot_to_file
 
 
-def test_dbus_success_skips_spectacle(monkeypatch, tmp_path) -> None:
+def test_dbus_success_skips_spectacle(monkeypatch: pytest.MonkeyPatch, tmp_path: Path) -> None:
     """A successful D-Bus capture returns immediately; spectacle is not called."""
     calls: list[str] = []
 
-    def fake_dbus(address: str, path, *, include_cursor: bool = False):
+    def fake_dbus(address: str, path: Path, *, include_cursor: bool = False) -> Path:
         calls.append("dbus")
         path.write_bytes(b"png")
         return path
@@ -40,15 +45,23 @@ def fake_dbus(address: str, path, *, include_cursor: bool = False):
     assert path.parent == tmp_path
 
 
-def test_dbus_failure_falls_back_to_spectacle(monkeypatch, tmp_path) -> None:
+def test_dbus_failure_falls_back_to_spectacle(
+    monkeypatch: pytest.MonkeyPatch, tmp_path: Path
+) -> None:
     """A D-Bus failure (DBusException) degrades to spectacle, not an error."""
     calls: list[str] = []
 
-    def failing_dbus(address: str, path, *, include_cursor: bool = False):
+    def failing_dbus(address: str, path: Path, *, include_cursor: bool = False) -> Path:
         calls.append("dbus")
         raise dbus.DBusException("not authorized")
 
-    def fake_spectacle(address: str, socket: str, *, output_path, include_cursor: bool = False):
+    def fake_spectacle(
+        address: str,
+        socket: str,
+        *,
+        output_path: Path,
+        include_cursor: bool = False,
+    ) -> None:
         calls.append("spectacle")
         output_path.write_bytes(b"png")
 
@@ -60,13 +73,21 @@ def fake_spectacle(address: str, socket: str, *, output_path, include_cursor: bo
     assert path.exists()
 
 
-def test_both_routes_failing_reports_both_errors(monkeypatch, tmp_path) -> None:
+def test_both_routes_failing_reports_both_errors(
+    monkeypatch: pytest.MonkeyPatch, tmp_path: Path
+) -> None:
     """When D-Bus and spectacle both fail, the error names both causes."""
 
-    def failing_dbus(address: str, path, *, include_cursor: bool = False):
+    def failing_dbus(address: str, path: Path, *, include_cursor: bool = False) -> Path:
         raise dbus.DBusException("not authorized")
 
-    def failing_spectacle(address: str, socket: str, *, output_path, include_cursor: bool = False):
+    def failing_spectacle(
+        address: str,
+        socket: str,
+        *,
+        output_path: Path,
+        include_cursor: bool = False,
+    ) -> None:
         raise RuntimeError("spectacle not found")
 
     monkeypatch.setattr(screenshot_module, "capture_screenshot_dbus", failing_dbus)
@@ -76,15 +97,24 @@ def failing_spectacle(address: str, socket: str, *, output_path, include_cursor:
         capture_screenshot_to_file("unix:path=/tmp/dbus", "wayland-0", output_dir=tmp_path)
 
 
-def test_frame_burst_skips_empty_frames(monkeypatch, tmp_path) -> None:
+def test_frame_burst_skips_empty_frames(monkeypatch: pytest.MonkeyPatch, tmp_path: Path) -> None:
     """Regression guard for the frame burst path: an empty frame is skipped in
     phase 2 instead of aborting the burst (pre-refactor behavior)."""
 
     from PIL import Image
 
-    def fake_raw_frame(iface, options):
+    saved: list[object] = []
+
+    def fake_raw_frame(
+        iface: dbus.Interface,
+        options: dict[str, dbus.Boolean],
+    ) -> tuple[bytes, int, int, int]:
         return b"", 0, 0, 0
 
+    def fake_frombytes(*args: object, **kwargs: object) -> object:
+        saved.append(args)
+        return object()
+
     class _StubBus:
         def __init__(self, *args: object, **kwargs: object) -> None:
             pass
@@ -95,8 +125,10 @@ def get_object(self, *args: object, **kwargs: object) -> object:
     monkeypatch.setattr(screenshot_module.dbus.bus, "BusConnection", _StubBus)
     monkeypatch.setattr(screenshot_module.dbus, "Interface", lambda *a: object())
     monkeypatch.setattr(screenshot_module, "_capture_raw_frame", fake_raw_frame)
+    monkeypatch.setattr(Image, "frombytes", fake_frombytes)
     frames = screenshot_module._capture_frame_burst_dbus(
         "unix:path=/tmp/dbus", tmp_path, [0], include_cursor=False
     )
     assert frames == []
-    assert Image  # PIL import inside the function is exercised by the call above
+    # Phase 2 must not attempt a PNG conversion of the empty frame either.
+    assert saved == []

tests/test_session_startup.py

@@ -114,18 +114,24 @@ def test_at_spi_launcher_falls_back_to_which(monkeypatch) -> None:
     assert session_module._at_spi_bus_launcher() == "/usr/local/bin/at-spi-bus-launcher"
 
     monkeypatch.setattr(session_module.shutil, "which", lambda name: None)
-    assert session_module._at_spi_bus_launcher() == "/nonexistent/a"
+    assert session_module._at_spi_bus_launcher() == "/usr/lib/at-spi-bus-launcher"
 
 
 def test_wrapper_script_contains_resolved_launcher(monkeypatch) -> None:
-    """The wrapper embeds the resolved launcher path, not a hardcoded one."""
+    """The wrapper embeds the resolved launcher path, not a hardcoded one, and
+    shell-quotes it so paths with special characters stay one argument."""
     monkeypatch.setattr(session_module, "_at_spi_bus_launcher", lambda: "/resolved/launcher")
     session = Session()
     session._socket_name = "wayland-mcp-test"
     script = session._build_wrapper_script(SessionConfig())
+    # shlex.quote leaves a plain path untouched (no spurious quotes).
     assert "/resolved/launcher --launch-immediately" in script
     assert "/usr/lib/at-spi-bus-launcher" not in script
 
+    monkeypatch.setattr(session_module, "_at_spi_bus_launcher", lambda: "/opt/my tools/launcher")
+    quoted = session._build_wrapper_script(SessionConfig())
+    assert "'/opt/my tools/launcher' --launch-immediately" in quoted
+
 
 def test_launch_app_strips_host_display(monkeypatch, tmp_path) -> None:
     """launch_app removes the host DISPLAY from the app environment so X11