SNTConfigurator: skip override-file watcher when overrides disabled

[mlw]

The DEBUG-only override-file watcher was dispatched onto a global queue unconditionally and held self in a polling loop. Under xctest's --runs_per_test, the worker block survived bundle teardown and aborted on objc_msgSend to a now-unloaded class, manifesting as a 1/25 flake in DaemonConfigBundleTest.

Gate the dispatch on the same xctest+ENABLE_CONFIG_OVERRIDES check that already short-circuits applyOverrides:, lifted into a shared overridesEnabled helper so both call sites can't drift.

[coderabbitai]

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ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 00adb322-e446-480a-a043-c4f95a876e32

📥 Commits

Reviewing files that changed from the base of the PR and between 801d6c9 and 924cdff.

📒 Files selected for processing (1)

• Source/common/SNTConfigurator.mm

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📝 Walkthrough

Walkthrough

SNTConfigurator refactors debug-only config override gating by extracting gate logic into a new overridesEnabled helper method. This helper centralizes DEBUG/xctest/environment checks. Both applyOverrides: and startWatchingDefaults now use this helper instead of embedding gate logic inline.

Changes

Config Override Gating Refactor

Layer / File(s)	Summary
Override Gate Helper Source/common/SNTConfigurator.mm	New overridesEnabled instance method determines whether the config override mechanism is active in the current process, respecting DEBUG build flag and ENABLE_CONFIG_OVERRIDES environment variable under xctest.
ApplyOverrides Gate Source/common/SNTConfigurator.mm	applyOverrides: replaces inline DEBUG/xctest conditional checks with an early-return guard that calls overridesEnabled.
Conditional Watcher Setup Source/common/SNTConfigurator.mm	startWatchingDefaults conditionally initiates the overrides-file watcher asynchronously only when overridesEnabled returns true, instead of always starting the watcher under DEBUG.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

🚥 Pre-merge checks | ✅ 2

✅ Passed checks (2 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately describes the main change: preventing the override-file watcher from starting when overrides are disabled, which is the core fix for the flaky test.
Description check	✅ Passed	The description clearly explains the problem (flaky test under xctest), the root cause (unconditional watcher dispatch), and the solution (gating dispatch with shared helper).

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch mlw/fix-flaky-daemon-cfg-bundle-test

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