Diagnostic: ThemeLifecycleProbe.java, run against copied QA jar matching build/libs jar.
Both jar SHA256: c854edbbea34d6cfc0e53ac9cf70ef5b2a5dcf550a3959ff0ed99d852950d433
Isolated java.util.prefs.userRoot and user.home. Headless JVM, no document mutation.
Observed 2026-09-24:
regular_is_disabled_instance=true
regular_filter_mutated=true
later_regular_keeps_mutation=true
probe_elapsed_ms=3004
probe_returned=dark

The 2-second SystemTheme timeout failed to bound a 3-second silent child process.
This proves the timeout defect; it does not measure a real desktop theme probe hanging.
