[rapheljr]

Resolves #276

Root Cause Analysis

In Steam Big Picture mode on macOS, clicking Resume Game deactivates the Big Picture UI and attempts to reactivate the game by calling ActivateApplication(pid) / ActivateProcess(pid) (in steamui.dylib and steamclient.dylib):

1. Steam executes:
   [NSRunningApplication runningApplicationWithProcessIdentifier:tracked_pid] activateWithOptions:NSApplicationActivateIgnoringOtherApps
2. For native macOS games, Steam tracks the game's GUI application process directly, which has an NSRunningApplication, so window activation succeeds.
3. For NotProton games, Steam spawns and tracks /bin/sh -c '...compat_run.sh waitforexitandrun ...'. Because /bin/sh is a non-GUI CLI process (not an application bundle), runningApplicationWithProcessIdentifier:sh_pid returns nil.
4. Steam then dispatches [nil activateWithOptions:2], which silently returns NO. Steam deactivates Big Picture, but WindowServer never brings the game forward, dropping focus to whatever inactive background window was behind Big Picture ("switching to the non-active application").

Solution

1. dylib/hooks/hook_activate.c:
   • Hook +[NSRunningApplication runningApplicationWithProcessIdentifier:].
   • If orig_running_app returns a valid NSRunningApplication, return it immediately (zero impact on native apps or already-recognized processes).
   • If orig_running_app returns nil for pid > 1:
     • Process Tree Resolution: Search descendant processes via proc_listchildpids() breadth-first to find child GUI processes like wine.app / wine64-preloader.
     • Launcher Bundle Fallback: When games are launched via open -n -W -a "$loader_app" (where launchd reparents the app to PID 1), inspect [[NSWorkspace sharedWorkspace] runningApplications] and resolve the newest, non-terminated application matching com.notproton.launcher.*.
2. overlay-shim/overlay_shim.m:
   • When the overlay deactivates (np_overlay_shim_set_active(0)), dispatch [[NSApplication sharedApplication] activateIgnoringOtherApps:YES] on the main thread inside Wine so the Cocoa game window regains key focus.
3. dylib/tests/activatecheck.c:
   • Add unit test coverage verifying:
     • Hook installation on NSRunningApplication.
     • Direct PID lookups returning original application.
     • Rejection of invalid PIDs (0, negative).
     • Child and multi-level descendant resolution via proc_listchildpids.
     • Fallback resolution of com.notproton.launcher.* applications with terminated filter and launch timestamp comparison.
     • Proper return of nil for unrelated processes.

Verification

All existing and new test suites pass with 0 failures:

• make -s activatecheck: passed (100%)
• make -s overlay-shim-tests: 10 passed, 0 skipped (100%)
• make -s launchercheck: all passed
• make -s envcheck: all passed
• make -s defaults-check: all passed
• make -s runcheck: all passed
• make -s scriptcheck: 28 scripts lint and parse clean
• Clean full rebuild (make clean && make -s all) succeeds and codesigns properly.

[NotProtonNot]

Thank you for this! This is getting merged!