fix: preserve window identity across native tabs

[qeude]

Summary

• Detect and coalesce native tab backing windows behind their Accessibility representative.
• Preserve window identity and runtime placement when native tab representatives change.
• Add diagnostics and comprehensive discovery/reconciliation coverage for native tabs.

Testing

• Not run (change request content only).

[greptile-apps]

Greptile Summary

The PR coalesces native macOS tab backing windows under their Accessibility representative and preserves logical window identity when that representative changes.

• Detects native tab groups and suppresses their physical backing windows during discovery.
• Propagates representative-ID replacements through runtime layout, fullscreen placement, selection, and pending focus state.
• Adds discovery, reconciliation, and displaced-focus recovery coverage.

Confidence Score: 5/5

The PR appears safe to merge.

No blocking failure remains.

Important Files Changed

Filename	Overview
Sources/DefiDaemon/DaemonDesktopSynchronization.swift	Applies representative replacements to prior selection, managed-window tracking, focus requests, and runtime reconciliation.
Sources/DefiDaemon/DaemonPointerFocusRecovery.swift	Rebinds command, workspace, and displaced-pointer focus state when native-tab representative IDs change, resolving the prior stale-identity path.
Sources/DefiMacOS/MacOSPlatform+WindowSnapshotDiscovery.swift	Detects and coalesces native-tab backing windows and emits live, unambiguous representative replacements.
Sources/DefiMacOS/WindowDiscoverySupport.swift	Adds native-tab grouping, matching, rebinding, and representative-replacement algorithms.
Sources/DefiRuntime/WindowReconciliation.swift	Rekeys runtime windows and associated layout and fullscreen placement state without removing and reinserting the logical window.
Tests/DefiDaemonTests/DaemonPointerFocusRecoveryTests.swift	Verifies displaced command-focus recovery adopts replacement target and previous-selection identities.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart LR
  AX[Accessibility window discovery] --> Tabs[Detect native tab group]
  Tabs --> Coalesce[Coalesce backing window IDs]
  Coalesce --> Replace[Derive representative ID replacement]
  Replace --> Runtime[Rekey runtime window and placement state]
  Replace --> Focus[Rebind pending and displaced focus requests]
  Runtime --> Stable[Preserve logical window identity]
  Focus --> Stable

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_{Reviews (3): Last reviewed commit: "Merge branch 'main' into fix/native-tabs" | Re-trigger Greptile}