[Crashlytics] com.google.mlkit:face-detection@@16.1.7 - com.google.mlkit.vision.face.bundled.internal.ThickFaceDetectorCreator.<clinit>

[stozo04]

Automated triage — a new fatal crash was reported by Firebase Crashlytics.

• Crashlytics-Issue-ID: 37081b243b0f5bf705e7e5e8ccd47489
• Title: com.google.mlkit:face-detection@@16.1.7 - com.google.mlkit.vision.face.bundled.internal.ThickFaceDetectorCreator.
• Subtitle: java.lang.UnsatisfiedLinkError - dlopen failed: library "libface_detector_v2_jni.so" not found
• First seen app version: 1.0.52
• Console: https://console.firebase.google.com/project/openloop-8c266/crashlytics/app/android:io.github.stozo04.openloop/issues/37081b243b0f5bf705e7e5e8ccd47489

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@claude please triage this crash. Use the Firebase MCP Crashlytics tools to fetch the
stacktrace and sample events for issue 37081b243b0f5bf705e7e5e8ccd47489, consult docs/lessons_learned/,
and post a root-cause comment. If you can point to a specific cause in the code, open a
draft PR with a minimal fix per docs/DEFINITION_OF_DONE.md (note CI could not run
the emulator). Otherwise label needs-human and explain. Never auto-merge.

[claude]

Root-cause analysis

MCP note: crashlytics_list_events returned an empty array (no sample events retrieved under this workflow's service-account auth — see issue #107). Triage is based on the issue metadata, the stacktrace in the title/subtitle, docs/lessons_learned/, and the source code.

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Failing frame

com.google.mlkit.vision.face.bundled.internal.ThickFaceDetectorCreator.<clinit>
java.lang.UnsatisfiedLinkError: dlopen failed: library "libface_detector_v2_jni.so" not found

Root cause

FaceTracker initializes the ML Kit face detector at field-init time with no error handling.

// camera/lens/FaceTracker.kt:50
private val detector = FaceDetection.getClient(
    FaceDetectorOptions.Builder()…
)

When this field is initialized, ML Kit's ThickFaceDetectorCreator.<clinit> (the bundled model's static initializer) calls System.loadLibrary("face_detector_v2_jni"). On affected devices, dlopen cannot find libface_detector_v2_jni.so — most likely because that device's ABI is not covered by the bundled ML Kit 16.1.7 AAR, or the library fails 16 KB page-alignment mapping on an Android 15 device with 16 KB page size. The resulting UnsatisfiedLinkError propagates uncaught as ExceptionInInitializerError → fatal crash.

Files involved

• app/src/main/java/io/github/stozo04/openloop/camera/lens/FaceTracker.kt — missing LinkageError guard
• app/src/main/java/io/github/stozo04/openloop/diagnostics/ReverseCrashlytics.kt — needs reportFaceTrackerUnavailable()

Lesson 040 precedent

HandTracker had the identical failure mode (MediaPipe's libmediapipe_tasks_jni.so absent / static initializer crash under R8), documented in docs/lessons_learned/040-run-the-release-apk-when-a-native-dependency-lands.md. The fix there: wrap tracker creation in try/catch (error: LinkageError), set a broken flag, report a non-fatal to Crashlytics, and degrade gracefully (camera still works, face lenses show pass-through).

FaceTracker was introduced alongside HandTracker but was never given the same resilience.

Fix

1. Move FaceDetection.getClient() from a field initializer into an init {} block with try/catch (error: LinkageError).
2. On failure: set broken = true, log, report non-fatal via ReverseCrashlytics.reportFaceTrackerUnavailable().
3. analyze() bails early when broken — camera and other lenses continue working.
4. Add reportFaceTrackerUnavailable() to ReverseCrashlytics.

Confidence: HIGH — the same crash shape, the same library load path, the same missing guard, and an existing pattern in the codebase to follow. A draft PR with the minimal fix follows.