dtourolleandClaude Opus 5
eaafacc3fb
Face indexing was compiled into the APK all along — dr-ui takes dr-face with `inference` on every target, so SCRFD, alignment, MBF, calibration and clustering were all in there. What was missing was the weights, and on Android there was no way to supply them. Route C (docs/faces.md §2.2) says the user obtains the model and the app loads it. On a desktop that is a real gesture: drop two files in ~/.local/share/darkroom/models/ and indexing starts working. On Android it is not a gesture at all. `internal_data_path` is app-private, `run-as` needs a debuggable build, and the in-app fetch route C specifies was never built — so the settings page reported "no face model is installed" on every launch with nothing behind the message. Not "off until you supply weights"; off. So the shape-fixed pair goes into LFS under the APK's assets, assemble-apk.sh copies it into the package, and `android_main` unpacks it to the shared models directory before anything asks whether a model is present. Three things that are not incidental: The models directory is now shared across accounts rather than per-account. Weights are identified by `faces.model_id`, not by who is signed in, so two accounts had no reason to hold two copies — and the unpack runs before any session exists to key a per-account path off. `face_models` still prefers a per-account directory when one is populated, so anyone mid-migration keeps the ability to pin one library to its own pair. The unpack writes under a temporary name and renames. `face_models` decides availability on `is_file()` alone, so a copy truncated by the process being killed would leave a file that passes that test and fails inside tract — reported to the user as a broken model rather than a missing one. assemble-apk.sh refuses an LFS pointer. At ~130 bytes it looks exactly like a model to `cp`, and unchecked it reaches the device and fails in the graph loader instead of telling someone to run `git lfs pull` — the same guard dr-segment's build script applies to yolo26n-seg.onnx. The licensing half is unchanged and recorded in §2.2a: the InsightFace grant is research-only, this is a private repository and a self-installed build, and these files come back out before anything is published. The weights are still not a cargo build input — dr-face has no `models/` directory and no `embedded-model` feature, and nothing in the build reads them. The APK assembly step copies two files and is the only thing in the tree that knows they exist. Verified on device: both models unpack on first launch (2524817 and 13616095 bytes) and the APK carries them at assets/models/. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Android build environment
Reproducible container for cross-compiling DarkRoom to Android. CI and local builds use the same image, so a break appears in one place rather than two.
Use
# Cross-compile for a device ABI
./docker/android/build.sh cargo ndk -t arm64-v8a build --release
# All four ABIs
./docker/android/build.sh cargo ndk -t arm64-v8a -t armeabi-v7a -t x86_64 -t x86 build --release
# Type-check without linking
./docker/android/build.sh cargo check --target aarch64-linux-android
# Interactive shell
./docker/android/build.sh
# After editing the Dockerfile
./docker/android/build.sh --rebuild
Prefers podman, falls back to docker. First run builds the image, which takes several minutes;
after that it is cached.
In CI
.gitea/workflows/android-image.yml builds this image and pushes it to
gitea.tourolle.paris/dtourolle/darkroom-android, which the Android job then runs inside. It is
called on every push and finishes in seconds unless something here changed — the image is tagged
with the git tree hash of docker/android/, so a rebuild happens when and only when a file in this
directory does.
Nothing needs pushing by hand. Editing the Dockerfile is the trigger; latest follows
automatically. To force a rebuild without a content change, run the workflow from the Gitea UI with
force set to true.
The job runs on the host runner rather than in a container, because it needs the Docker daemon and the runner host's cached registry credentials.
Face models
package.sh bundles apps/darkroom-android/android/assets/models/ into the APK, and the entry point
unpacks it on first launch. The models are in LFS, so a clone without git lfs pull has 130-byte
pointers there; the build detects that and stops rather than shipping them.
This exists because Android offers no other route to a model: the directory the app reads from is
inside app-private storage, run-as needs a debuggable build, and the app has no picker and no
fetch. docs/faces.md §2.2a is the decision and its limits — these files come back out before anything
is published.
Pinned versions
| Component | Version | Why this one |
|---|---|---|
| JDK | 17 | AGP's stable target. The host's JDK 25 breaks Gradle. |
| Compile SDK | API 36 | Required for Play distribution |
| Min API | 28 (Android 9) | Floor where Vulkan support is dependable (NFR-COMPAT-1) |
| Build tools | 36.0.0 | Matches compile SDK |
| NDK | 27.2.12479018 (r27c) | Current LTS |
| Rust | 1.92.0 | Slint 1.17 requires it; cargo-ndk 4.1.x needs ≥ 1.86 |
| cargo-ndk | 4.1.2 |
Bumping any of these is a reviewable change, not silent drift.
Compile SDK versus min API
These are different and both matter. ANDROID_API (36) is what the SDK compiles against — the
newest APIs available. MIN_API (28) is what native code links against, and determines the
oldest device that can run the result.
cargo-ndk defaults to API 21 if not told otherwise, which is far below what this app needs.
CARGO_NDK_PLATFORM and the per-target linker paths both pin it to MIN_API. Verify with:
file target/aarch64-linux-android/release/*.so
# → "... for Android 28, built by NDK r27c"
Caching
The cargo registry and target directory persist in ~/.cache/darkroom-android, so rebuilds do not
re-download the crate index. Clear with:
rm -rf ~/.cache/darkroom-android
The Android target dir is kept separate from the host's target/ — sharing one directory between
host and container builds causes constant rebuilds as they invalidate each other's fingerprints.
What is not here
No emulator, no adb device access. This image cross-compiles; it does not run or deploy. Device
testing (spikes S2 and S10, which need two GPU vendors) happens on real hardware — the emulator's
GPU behaviour is not representative of Adreno or Mali, which is precisely what those spikes exist
to test.