Skip to content

hook-debugging.md

Latest commit

 

History

History
130 lines (87 loc) · 3.88 KB

hook-debugging.md

File metadata and controls

130 lines (87 loc) · 3.88 KB
Raw

Hidden-App Hook Debugging

This is an internal engineering note. It captures a specific debugging thread for contributors working on helper behavior and Dock re-promotion issues.

Context

GhostTile originally hid apps by injecting a helper into the target process and blocking the app from promoting itself back into the Dock.

The modern rewrite now loads the helper persistently by:

  • patching the managed app binary with LC_LOAD_DYLIB @rpath/ghosthide.dylib
  • staging the helper at Contents/Frameworks/ghosthide.dylib
  • re-signing the modified binary and bundle ad hoc

This replaces the earlier DYLD_INSERT_LIBRARIES-only launch path and allows normal app launches to keep the helper loaded.

Useful Release Hooks

These hooks remain in the release helper because they are useful and correspond to real promotion behavior:

  • -[NSApplication setActivationPolicy:]
  • -[NSApplication activateIgnoringOtherApps:]
  • TransformProcessType

GhostTile uses the saved original TransformProcessType only for its own explicit show and hide transitions.

Probes That Were Tested

These hooks were tested during debugging but are not kept in the release helper:

  • -[NSApplication unhide:]
  • -[NSWindow makeKeyAndOrderFront:]
  • applicationShouldHandleReopen:hasVisibleWindows: on Electron's app delegate
  • -[NSRunningApplication activateWithOptions:]
  • SetFrontProcess
  • SetFrontProcessWithOptions

Legcord Repro

Target app:

  • Legcord
  • Electron version 40.6.0

Relevant Legcord app code that was inspected:

  • src/discord/tray.ts
    • tray click calls mainWindow.show()
  • src/discord/window.ts
    • app activate handler calls app.show()

Relevant Electron macOS code that was checked:

  • NativeWindowMac::Show()
    • activateIgnoringOtherApps:YES
    • makeKeyAndOrderFront:nil
  • Browser::Show()
    • unhide:nil
  • Browser::DockShow()
    • TransformProcessType(...Foreground)
    • activateWithOptions(...)

Test Method

  1. Build debug helper:
GHOSTHIDE_DEBUG=1 just build-cli
  1. Re-prepare Legcord:
./.build/release/ghosttile prepare --force /Applications/legcord.app
  1. Launch Legcord normally:
open -a /Applications/legcord.app
  1. Click the Dock icon through UI scripting:
osascript <<'APPLESCRIPT'
tell application "System Events"
  tell process "Dock"
    click UI element "Legcord" of list 1
  end tell
end tell
APPLESCRIPT
  1. Inspect:
  • activation policy through NSWorkspace.shared.runningApplications
  • helper log at ~/.config/ghosttile/ghosthide.log

Final Legcord Findings

Fresh Dock-click repro on a hidden Legcord process showed:

  • activateIgnoringOtherApps intercepted, flag=1 hidden=1
  • makeKeyAndOrderFront intercepted, window=Legcord sender=nil hidden=1

What did not fire on the decisive repro:

  • unhide
  • activateWithOptions
  • TransformProcessType
  • applicationShouldHandleReopen:hasVisibleWindows:

Even with activateIgnoringOtherApps: and makeKeyAndOrderFront: blocked in-process, Legcord still flipped from NSApplicationActivationPolicyAccessory to NSApplicationActivationPolicyRegular.

Conclusion

For Electron apps like Legcord, Dock activation can still promote the process back to a regular app outside the direct in-process methods we tested.

Practical implication:

  • more in-process hooks are unlikely to fully solve Dock-click re-promotion cleanly
  • a future "sticky hidden" behavior should be treated as an explicit option that re-applies hidden state after activation
  • do not re-add unhide, makeKeyAndOrderFront, or delegate reopen hooks to release mode without a new confirmed repro that shows they are the decisive enforcement point

Current Recommendation

  • keep the release helper minimal
  • preserve debug-only logging infrastructure for future targeted investigations
  • add any stronger post-activation enforcement behind a user preference instead of making it the default behavior