Dock tile icon

The system ⌘Tab runs inside the Dock process and reads the tile image directly (-[ASAppSwitcher show:] calls -[Tile getImage:glassCompositingFilter:]). The Dock exposes no call that returns a tile image to another process: its DockExtraServer and CoreDock* entry points only set images. So each app whose Dock icon differs gets a hand-written entry in BetterCmdTab/Catalog/DockTileIcon.swift that rebuilds the same icon from the app's own bundle and preferences.

1. Classify the mismatch

Compare three icons: the Dock tile, the system ⌘Tab (quit BetterCmdTab, then press ⌘Tab) and the BetterCmdTab tile. Then pick the class:

• Finder custom icon (Get Info, NSWorkspace.setIcon): NSRunningApplication.icon already returns it. If the tile still differs, it is a stale IconCache entry, not a DockTileIcon case.
• Dock-only static icon: the app sets NSApp.applicationIconImage or ships an NSDockTilePlugIn that picks one of a few icons from a preference or the appearance. This is the only class DockTileIcon handles.
• Live content (Calendar date, Clock hands, progress bars, badges): drawn every minute or on events. Out of scope: report it and stop.

Complete when: the app is in exactly one class, with the evidence named.

2. Find the icon source

For a Dock-only static icon, find three facts in the app bundle:

1. The images: plutil -extract NSDockTilePlugIn raw <app>/Contents/Info.plist names the plugin; assetutil --info <app>/Contents/Resources/Assets.car lists the alternate icon names (cmux: AppIconDark, AppIconLight).
2. The selector: the defaults key and values that pick the image. defaults read <bundle id> while flipping the in-app setting shows it; the app's source or strings on the plugin binary confirms the values.
3. The change signal: a distributed notification the app posts when the icon changes (cmux: com.cmuxterm.appIconDidChange). Search the source or strings for a reverse-DNS name. No signal means the system appearance notification is the only eviction trigger, so say so in the report.

Closed-source app: decompile the plugin with the rea CLI (Hopper at /Applications/Hopper Disassembler.app, set HOPPER_LAUNCHER_PATH to its Contents/MacOS/hopper) and read the method that calls setContentView: or setApplicationIconImage:.

Complete when: each of the three facts has a concrete value, or is confirmed absent.

3. Add the entry

In DockTileIcon.swift, match on the bundle identifier, read the selector with CFPreferencesAppSynchronize then CFPreferencesCopyAppValue (the app's domain, not ours), and load the image with Bundle(url:).image(forResource:). Return nil for anything unmatched so IconCache falls back to the bundle icon. Add the change notification to observeChanges() and evict that bundle identifier.

Keep it on the cache-miss path only: IconCache calls DockTileIcon before caching, so the ⌘Tab hot path never reads a bundle. Match the stable bundle identifier only; nightly and beta builds show their bundle icon.

Complete when: xc build passes.

4. Verify

Run the Debug build, open the switcher with macui chord 1500 48, and compare the tile to the Dock in every selector value and in light and dark appearance. Flip the setting while BetterCmdTab runs: the next ⌘Tab shows the new icon without a relaunch. Restore the app's original setting afterwards, and quit with osascript -e 'quit app "BetterCmdTab Debug"'.

Complete when: a screenshot per selector value matches the Dock.