This looks great, Mozart! Really nice overhaul! I did an AI code review and some manual testing.

Manual testing comments:

1. The labels at the top of each demo are inconsistent. I like that they tell you what demo you're in, but in some of the demos the label is missing (for example, "Take a video"). Also, some of them have the demo name label lower on the screen than others (for example, Zoom & Torch has the label a bit low, and the "x" button and "torch" button are on a different y-value as well, making the buttons feel a little off). This was tested on a Pixel 9 Pro.
2. There are some Camera2 examples that are easier to do CameraX, but there is no CameraX sample. For example, slow motion video capture and Raw DNG photo capture. Both of these CameraX features are explained in this blog post: https://developer.android.com/blog/posts/introducing-camera-x-powerful-video-recording-and-pro-level-image-capture. And Viewfinder Effects are possible in CameraX with the CameraX-Media3-effects bridge, which is exaplined in this blog post: https://android-developers.googleblog.com/2024/12/whats-new-in-camerax-140-and-jetpack-compose-support.html
3. It would be nice to have a toast message when media is saved in all of the demos.
4. Consistent controls. For example, Take a Photo has "Retake" and "Done" buttons after capture, but Take a Video only has a back button in the upper left-hand corner after capture.
5. The CameraX Extensions demo is bugging for me. When I click the capture button, it flashes what I think the the post capture screen, but then it takes me back to the preview screen and no photo is saved.
6. Concurrent camera has a round rect over the front facing feed. Is that meant to be a mask, so that the front feed has a sleek rounded look?
7. The UIs for the CameraX and Camera2 effects demos are different. Not a major issue, but I found it odd. Also, the "Invert" effects aren't the same. I think the Camera2 one applies a B&W filter and then inverts it, and the CameraX one actually inverts the colors.

AI review comments:

🏗️ 1. Code Pattern & Architecture Review
Status: EXCELLENT
The architectural overhaul is highly successful, introducing significant improvements in maintainability and readability.

• Architectural Consistency: The 26 new sample modules demonstrate strict adherence to a modern MVVM/MVI architecture. Each sample is cleanly divided into a Screen (UI), ViewModel (state orchestration),
  UiState (MVI pattern via StateFlow), and a Controller (Camera API plumbing).
• DRY Principles: The extraction of core-camera and core-ui was highly effective. Complex Camera2 boilerplate (background threads, lifecycle, tap-to-focus) is abstracted cleanly into BaseCamera2Controller.
  Reusable Compose UI elements (CameraSampleScaffold, FocusIndicator, etc.) ensure a uniform aesthetic and eliminate redundant code.

🛡️ 2. Security Review
Status: CRITICAL ISSUE FOUND

• 🔴 Improper Scoped Storage Access (MediaStoreSaver.kt): There is a critical flaw in how new video files are created for Camera2 samples. The newVideoFile() function uses
  Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DCIM) and writes directly to java.io.File. Starting in Android 10 (API 29), apps are restricted from directly writing to shared storage
  without Scoped Storage compliant APIs. This will result in a SecurityException or IOException (Permission denied) crash on modern Android versions.
  • Fix: Refactor to use the MediaStore API (inserting a pending MediaStore.Video.Media.EXTERNAL_CONTENT_URI record) or write to scoped storage (Context.getExternalFilesDir()).
• 🟢 Manifest & Intents: MainActivity is correctly exported for Android 12+. The FileProvider is safely configured without path traversal vulnerabilities.
• 🟡 Permissions: Use of @SuppressLint("MissingPermission") in controllers is deemed acceptable here because permissions are explicitly verified at the UI layer by CameraSampleScaffold.kt before
  initialization.

🏎️ 3. Performance & Memory Review
Status: CRITICAL ISSUES FOUND

• 🔴 Leaked ImageProxy Instances: In controllers like CameraXTakeAPhotoController, the ImageProxy received in onCaptureSuccess is handed off to a Compose-tied coroutine. If the Composable is disposed and the
  coroutine cancels, image.close() is never called, exhausting the ImageReader buffer and permanently stalling the camera pipeline.
  • Fix: Convert the ImageProxy to a Bitmap (or extract the buffer) synchronously inside onCaptureSuccess, close it via finally, and then launch the coroutine to pass the result.
• 🔴 Activity Context Leaks: Controllers are injected with LocalContext.current (an Activity Context) and passed directly to ProcessCameraProvider.getInstance(context).
  • Fix: Always use context.applicationContext to prevent leaking the Activity singleton.
• 🟡 Thread Pool Leaks: Controllers define Executors.newSingleThreadExecutor() and are managed by Compose's remember. If not properly disposed in a DisposableEffect, threads will leak.
• 🟡 Unstable UI State Parameters: UI State classes use standard Kotlin Lists (e.g., val availableModes: List). Compose treats List as unstable, forcing unnecessary recompositions of the camera UI tree.
  • Fix: Use @immutable data classes or ImmutableList from kotlinx.collections.immutable.
• 🟡 Unbounded Coroutines: ViewModels process images via indiscriminate viewModelScope.launch { withContext(Dispatchers.IO) }. Spamming capture can spike memory allocations and lead to an OutOfMemoryError.

📱 4. Modern Android Development (MAD) Review
Status: GOOD WITH MINOR DEVIATIONS
The codebase makes excellent use of Jetpack Compose, Coroutines, StateFlow, and Dagger Hilt. However, there are a few deviations from idiomatic practices:

• 🟡 Imperative Future Handling: In controllers, ProcessCameraProvider.getInstance(context) is resolved using .addListener(...).
  • Idiomatic Approach: Use the androidx.concurrent:concurrent-futures-ktx artifact and await the result cleanly using Coroutines: ProcessCameraProvider.getInstance(context).await().
• 🟡 Verbose hiltViewModel(): hiltViewModel(checkNotNull(LocalViewModelStoreOwner.current)) is used in UI screens.
  • Idiomatic Approach: Just call hiltViewModel() without arguments; it automatically resolves the current LocalViewModelStoreOwner.
• 🟡 Callback Stability in remember: Passing callbacks like viewModel::onCameraReady as a remember key in screens can cause unintended controller recreations.
  • Idiomatic Approach: Use rememberUpdatedState for callbacks inside remembered components to ensure they invoke the latest reference without recreation.
• 🟡 Internal ViewModel State: Standalone mutable variables (like var isFrontCamera) require imperative methods to reconstruct and push the entire UI state.
  • Idiomatic Approach: Fold these properties into a unified state data class or use flow combine operators for a true single source of truth.