linux observer
activity: skip FDO ScreenSaver probe on GNOME (idle-inhibit-only endpoint)
GNOME's org.freedesktop.ScreenSaver serves only the idle-inhibit
endpoints defined in the FDO idle-inhibit spec (Inhibit, UnInhibit,
SimulateUserActivity). GetActive is not part of the spec, so calling
it on GNOME raises DBusError("This method is not part of the idle
inhibition specification") — not ServiceUnknown/NameHasNoOwner. The
observable-probes rewrite in cbf581d made this surface as a WARN
every 5 s on GNOME Wayland hosts.
Detect GNOME at call time via case-insensitive token-equality match
on XDG_CURRENT_DESKTOP (colon-split, whitespace-stripped) and skip
the FDO branch entirely on GNOME. Non-GNOME desktops are unchanged
— FDO-first, GNOME fallback. The FDO block remains reachable on
KDE/XFCE/Cinnamon/MATE/etc.
Surfacing trail: lode 7ppx4a7g. Decision to go with
GNOME-as-early-skip (option b) recorded 2026-04-22.
Co-Authored-By: OpenAI Codex <codex@openai.com>
+99
-22
+36
-22
src/solstone_linux/activity.py
+36
-22
src/solstone_linux/activity.py
···
76
76
)
77
77
78
78
79
+
def _is_gnome_desktop() -> bool:
80
+
"""True if any XDG_CURRENT_DESKTOP token equals 'gnome' (case-insensitive)."""
81
+
return any(
82
+
token.strip().casefold() == "gnome"
83
+
for token in os.environ.get("XDG_CURRENT_DESKTOP", "").split(":")
84
+
)
85
+
86
+
79
87
async def _name_has_owner(bus: MessageBus, bus_name: str) -> bool:
80
88
"""Ask the bus daemon whether a well-known name is currently owned.
81
89
···
145
153
146
154
147
155
async def is_screen_locked(bus: MessageBus) -> bool:
148
-
"""Check if the screen is locked via FDO ScreenSaver, then GNOME ScreenSaver.
156
+
"""Check if the screen is locked.
149
157
150
-
Returns True if locked, False if unlocked or all backends unavailable.
158
+
On GNOME, probes only org.gnome.ScreenSaver — the FDO ScreenSaver bus
159
+
on GNOME serves idle-inhibit endpoints only and does not implement
160
+
GetActive. On non-GNOME desktops, tries FDO ScreenSaver first (KDE
161
+
kwin and other compliant desktops), then falls back to GNOME
162
+
ScreenSaver. Returns True if locked, False if unlocked or all
163
+
backends unavailable.
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164
"""
152
-
# Try freedesktop.org ScreenSaver first (KDE kwin + GNOME)
153
-
try:
154
-
intro = await bus.introspect(FDO_SCREENSAVER_BUS, FDO_SCREENSAVER_PATH)
155
-
obj = bus.get_proxy_object(FDO_SCREENSAVER_BUS, FDO_SCREENSAVER_PATH, intro)
156
-
iface = obj.get_interface(FDO_SCREENSAVER_IFACE)
157
-
return bool(await iface.call_get_active())
158
-
except (
159
-
DBusError,
160
-
InvalidMemberNameError,
161
-
InvalidIntrospectionError,
162
-
OSError,
163
-
) as exc:
164
-
if not _is_service_missing(exc):
165
-
logger.warning(
166
-
"is_screen_locked FDO backend failed: service=%s path=%s: %s: %s",
167
-
FDO_SCREENSAVER_BUS,
168
-
FDO_SCREENSAVER_PATH,
169
-
type(exc).__name__,
170
-
exc,
171
-
)
165
+
if not _is_gnome_desktop():
166
+
# Try freedesktop.org ScreenSaver first (KDE kwin and other non-GNOME desktops)
167
+
try:
168
+
intro = await bus.introspect(FDO_SCREENSAVER_BUS, FDO_SCREENSAVER_PATH)
169
+
obj = bus.get_proxy_object(FDO_SCREENSAVER_BUS, FDO_SCREENSAVER_PATH, intro)
170
+
iface = obj.get_interface(FDO_SCREENSAVER_IFACE)
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+
return bool(await iface.call_get_active())
172
+
except (
173
+
DBusError,
174
+
InvalidMemberNameError,
175
+
InvalidIntrospectionError,
176
+
OSError,
177
+
) as exc:
178
+
if not _is_service_missing(exc):
179
+
logger.warning(
180
+
"is_screen_locked FDO backend failed: service=%s path=%s: %s: %s",
181
+
FDO_SCREENSAVER_BUS,
182
+
FDO_SCREENSAVER_PATH,
183
+
type(exc).__name__,
184
+
exc,
185
+
)
172
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187
# Fall back to GNOME ScreenSaver
174
188
try:
+63
tests/test_activity.py
+63
tests/test_activity.py
···
49
49
class TestIsScreenLocked:
50
50
"""Test screen lock fallback order."""
51
51
52
+
@pytest.fixture(autouse=True)
53
+
def _clear_xdg_desktop(self, monkeypatch):
54
+
monkeypatch.delenv("XDG_CURRENT_DESKTOP", raising=False)
55
+
52
56
@pytest.mark.asyncio
53
57
async def test_fdo_backend_returns_true_without_gnome_fallback(self):
58
+
bus = MagicMock()
59
+
bus.introspect = AsyncMock(return_value=object())
60
+
iface = MagicMock()
61
+
iface.call_get_active = AsyncMock(return_value=True)
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+
bus.get_proxy_object.return_value = _make_proxy_with_interface(iface)
63
+
64
+
result = await activity.is_screen_locked(bus)
65
+
66
+
assert result is True
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+
assert bus.introspect.await_count == 1
68
+
bus.introspect.assert_awaited_once_with(
69
+
activity.FDO_SCREENSAVER_BUS, activity.FDO_SCREENSAVER_PATH
70
+
)
71
+
72
+
@pytest.mark.asyncio
73
+
async def test_xdg_current_desktop_ubuntu_gnome_skips_fdo_and_returns_gnome_state(
74
+
self, monkeypatch, caplog
75
+
):
76
+
monkeypatch.setenv("XDG_CURRENT_DESKTOP", "ubuntu:GNOME")
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+
bus = MagicMock()
78
+
bus.introspect = AsyncMock(return_value=object())
79
+
iface = MagicMock()
80
+
iface.call_get_active = AsyncMock(return_value=True)
81
+
bus.get_proxy_object.return_value = _make_proxy_with_interface(iface)
82
+
83
+
with caplog.at_level(logging.WARNING):
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+
result = await activity.is_screen_locked(bus)
85
+
86
+
assert result is True
87
+
assert bus.introspect.await_args_list == [
88
+
call(activity.GNOME_SCREENSAVER_BUS, activity.GNOME_SCREENSAVER_PATH)
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+
]
90
+
assert not any(
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+
"is_screen_locked FDO backend failed" in record.message
92
+
for record in caplog.records
93
+
)
94
+
95
+
@pytest.mark.asyncio
96
+
async def test_xdg_current_desktop_kde_still_probes_fdo_first(self, monkeypatch):
97
+
monkeypatch.setenv("XDG_CURRENT_DESKTOP", "KDE")
98
+
bus = MagicMock()
99
+
bus.introspect = AsyncMock(return_value=object())
100
+
iface = MagicMock()
101
+
iface.call_get_active = AsyncMock(return_value=True)
102
+
bus.get_proxy_object.return_value = _make_proxy_with_interface(iface)
103
+
104
+
result = await activity.is_screen_locked(bus)
105
+
106
+
assert result is True
107
+
assert bus.introspect.await_count == 1
108
+
bus.introspect.assert_awaited_once_with(
109
+
activity.FDO_SCREENSAVER_BUS, activity.FDO_SCREENSAVER_PATH
110
+
)
111
+
112
+
@pytest.mark.asyncio
113
+
async def test_xdg_current_desktop_not_gnome_does_not_match_substring(
114
+
self, monkeypatch
115
+
):
116
+
monkeypatch.setenv("XDG_CURRENT_DESKTOP", "NOT-GNOME")
54
117
bus = MagicMock()
55
118
bus.introspect = AsyncMock(return_value=object())
56
119
iface = MagicMock()