VS Code's rust-analyzer extension ships a server newer than 1.92.0
supports and prompts, on every window, to add one. Listing the component
in rust-toolchain.toml makes rustup supply the server matching the pin —
the same thing the pin buys everywhere else.

The cost lands outside the editor, which is why this is four files
rather than one. rustup reconciles that component list against the
installed toolchain on the first cargo call in the work tree and
downloads what is missing, inside whatever job happens to be running. An
unasked-for fetch in the middle of a build step is nobody's line item
and hard to find in a log. So every environment that builds this repo
names it too: baked into the Android image, and in the install step of
each CI job that rolls its own toolchain.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

2026-08-29 23:21:44 +02:00

assemble-apk.sh

Let a test build be opened up, when asked

2026-08-29 08:32:01 +02:00

build.sh

Add the Android app shell; cap cross-build parallelism

2026-08-09 21:10:00 +02:00

Dockerfile

Name rust-analyzer everywhere the toolchain is installed

2026-08-29 23:21:44 +02:00

package.sh

Let a test build be opened up, when asked

2026-08-29 08:32:01 +02:00

README.md

Package the models on every platform, not just the phone

2026-08-27 18:05:23 +02:00

README.md

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 models/face/ into the APK, and the entry point unpacks it on first launch. That directory is shared with the Arch package rather than owned by this platform. 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.