v1.2.2: never let Night Shift toggles flip the Light/Dark theme

CLAUDE.md

@@ -97,6 +97,9 @@ The bridge registers a `setStatusNotificationBlock:` handler (delivered on the m
 
 Known remaining edge: if an override spans the *end* of a schedule window (e.g. in Photoshop from 11pm past sunrise), the snapshotted restore intent re-enables Night Shift outside schedule hours when focus leaves. Detecting this would require parsing schedule times from the private status struct.
 
+### Appearance Guard (Auto Light/Dark coupling)
+On some macOS versions (confirmed on Sonoma 14.5; apparently decoupled on newer releases), the "Auto" appearance setting is tied to the Night Shift engine: toggling Night Shift flips the system Light/Dark theme as a side effect. The bridge guards every `setNightShiftEnabled:` call — it snapshots the theme (SkyLight `SLSGetAppearanceThemeLegacy`) and restores it (`SLSSetAppearanceThemeLegacy`) if it changes within ~3s of our toggle, checking at 0.3/1.2/3.0s with a generation counter so rapid toggles don't fight. The guard is behavior-neutral on OSes without the coupling (it only acts when a flip actually happens) and never touches theme changes made outside our own calls.
+
 ### Global Night Shift Toggle (menu bar)
 The menu bar has a "Turn On/Off Night Shift" item (`NightShiftManager.setGlobalEnabled(_:)`). Calling `setEnabled:` is the same thing System Settings' toggle does — when a schedule is configured, the OS itself handles the "until tomorrow / until sunset" scheduling.
 
@@ -117,6 +120,7 @@ When making changes:
    - Menu bar "Turn Off Night Shift" while warming → display unshifts; System Settings shows it off until the next schedule trigger
    - Menu bar toggle while an excluded app is in focus → display must NOT change; the chosen state applies when focus leaves the excluded app
    - Toggle Night Shift in System Settings/Control Center → menu status line and toggle title reflect the change
+   - With Appearance set to "Auto" (System Settings → Appearance), use the menu toggle and switch in/out of an excluded app → the Light/Dark theme must NOT change (macOS couples Auto appearance to Night Shift on some OS versions; the bridge's appearance guard must undo it)
    - Quit the app while overriding → Night Shift should restore
    - Launch the packaged .app from the DMG **with `.build` renamed away** — the baked-in fallback path makes dev-machine launch tests pass even when the packaged app is broken (CI's release smoke test also covers this)
 4. **Release:** merge to `main` with the bumped VERSION file. The release workflow (`.github/workflows/release.yml`) triggers on VERSION changes to main, builds the DMG, creates the `v<VERSION>` tag and GitHub release, and updates the Homebrew cask automatically. It skips silently if the version is already tagged, so a re-run is always safe. (Manual fallback: `./scripts/create-dmg.sh` then `gh release create v<VERSION> ./ShiftChange-<VERSION>.dmg --title "ShiftChange <VERSION>" --notes "<changelog>"`.)

README.md

@@ -65,6 +65,7 @@ That's it. Set it and forget it.
 - **Per-app Night Shift control** — disable Night Shift only when specific apps are in focus
 - **Global Night Shift toggle** — turn Night Shift on or off system-wide right from the menu bar, exactly like the System Settings toggle ("Turn Off Until Tomorrow" / "Turn On Until Sunset"). Per-app switching keeps working either way
 - **Schedule-aware** — if your Night Shift schedule kicks in while a color-critical app is in focus, the display stays unshifted until you switch away
+- **Theme-safe** — toggling Night Shift never flips your Light/Dark appearance (some macOS versions couple the two when Appearance is set to Auto; ShiftChange guards against it)
 - **Menu bar app** — runs quietly out of the way with a status icon
 - **Instant switching** — Night Shift toggles the moment you switch apps, no delay
 - **Smart restore** — respects your existing Night Shift schedule; restores it when you leave an excluded app

ShiftChange/Sources/CBlueLightBridge/CBlueLightBridge.m

@@ -14,6 +14,44 @@
     unsigned char _padding[508];
 } BlueLightStatus;
 
+#pragma mark - Appearance guard (SkyLight)
+
+// macOS couples the "Auto" appearance setting to the Night Shift engine:
+// toggling Night Shift can flip the system Light/Dark theme as a side
+// effect. Night Shift tinting and the theme are independent settings from
+// the user's point of view, so we snapshot the theme before our own
+// setEnabled: calls and restore it if it changes in the seconds after.
+// Scoped to OUR toggles only — theme changes made by the user or by the
+// schedule outside our calls are left alone.
+
+typedef BOOL (*SLSGetAppearanceThemeLegacyFunc)(void);
+typedef void (*SLSSetAppearanceThemeLegacyFunc)(BOOL);
+
+static SLSGetAppearanceThemeLegacyFunc slsGetTheme = NULL;
+static SLSSetAppearanceThemeLegacyFunc slsSetTheme = NULL;
+static NSUInteger themeGuardGeneration = 0;
+
+static void loadSkyLightIfNeeded(void) {
+    static dispatch_once_t onceToken;
+    dispatch_once(&onceToken, ^{
+        void *handle = dlopen(
+            "/System/Library/PrivateFrameworks/SkyLight.framework/SkyLight",
+            RTLD_LAZY
+        );
+        if (!handle) {
+            NSLog(@"[ShiftChange] Failed to load SkyLight — appearance guard disabled");
+            return;
+        }
+        slsGetTheme = (SLSGetAppearanceThemeLegacyFunc)dlsym(handle, "SLSGetAppearanceThemeLegacy");
+        slsSetTheme = (SLSSetAppearanceThemeLegacyFunc)dlsym(handle, "SLSSetAppearanceThemeLegacy");
+        if (!slsGetTheme || !slsSetTheme) {
+            NSLog(@"[ShiftChange] SkyLight appearance symbols not found — appearance guard disabled");
+            slsGetTheme = NULL;
+            slsSetTheme = NULL;
+        }
+    });
+}
+
 @implementation CBlueLightBridge
 
 + (id _Nullable)sharedClient {
@@ -81,9 +119,35 @@ + (void)setNightShiftEnabled:(BOOL)enabled {
         return;
     }
 
-    void (*setEnabled)(id, SEL, BOOL) =
+    // Snapshot the theme so the appearance guard can undo any Light/Dark
+    // flip this toggle causes (see the guard comment above).
+    loadSkyLightIfNeeded();
+    BOOL guardActive = (slsGetTheme != NULL && slsSetTheme != NULL);
+    BOOL themeBefore = guardActive ? slsGetTheme() : NO;
+    NSUInteger generation = ++themeGuardGeneration;
+
+    void (*setEnabledFn)(id, SEL, BOOL) =
         (void (*)(id, SEL, BOOL))objc_msgSend;
-    setEnabled(client, sel, enabled);
+    setEnabledFn(client, sel, enabled);
+
+    if (!guardActive) return;
+
+    // The appearance engine reacts asynchronously, so check a few times.
+    // A newer toggle supersedes this guard via the generation counter.
+    void (^restoreTheme)(void) = ^{
+        if (generation != themeGuardGeneration) return;
+        if (slsGetTheme() != themeBefore) {
+            NSLog(@"[ShiftChange] Night Shift toggle flipped the system appearance — restoring");
+            slsSetTheme(themeBefore);
+        }
+    };
+    for (NSNumber *delay in @[@0.3, @1.2, @3.0]) {
+        dispatch_after(
+            dispatch_time(DISPATCH_TIME_NOW, (int64_t)(delay.doubleValue * NSEC_PER_SEC)),
+            dispatch_get_main_queue(),
+            restoreTheme
+        );
+    }
 }
 
 + (BOOL)isNightShiftScheduled {

ShiftChange/Sources/ShiftChange/Resources/VERSION

@@ -1 +1 @@
-1.2.1
+1.2.2