ANDROID_PLATFORM means "link native code for API 28" to cargo-ndk, but the
android-build crate reads the same variable as "compile Java against
platforms/android-28/android.jar" — a directory that does not exist in the
image, because only the compile SDK is installed. Slint's Android backend
builds a Java helper through that crate, so it panicked with "No Android
platforms found" while android.jar sat in android-36.
ANDROID_JAR is checked ahead of the platform lookup and settles it: Java
compiles against the compile SDK, native code still links against MIN_API.
The two are meant to differ; only the variable name is overloaded.
Assisted-by: LLM
Correcting the previous commit: I claimed VFS placeholders could not be
downloaded. That was wrong. The desktop client exposes a socket at
$XDG_RUNTIME_DIR/Nextcloud/socket speaking newline-delimited
COMMAND:argument, and MAKE_AVAILABLE_LOCALLY:<path> does fetch the file.
Verified against client 4.0.7: a 1-byte stub became a real 2.8MB file in
2.8 seconds.
Implemented as dr-sync-nextcloud::desktop_client, deliberately optional.
Android has no desktop client, no XDG_RUNTIME_DIR socket and no
placeholders, so detect() returns None there and callers fall back to the
connector. It earns its place only because it is ~30 lines with no
dependencies: where a library already lives in a VFS folder, asking the
client to fetch beats downloading a second copy over WebDAV and leaving
the client's placeholder state inconsistent.
What this does not change: hydration is whole-file, so it suits the
original tier and never browsing. Filling a grid this way downloads the
entire library. Range extraction remains the only mechanism satisfying
FR-NC-3, and ARCH §9.0 now says so precisely.
Also fixes two real Android build failures found by cross-compiling:
- reqwest's `rustls` feature defaults to aws-lc-rs, whose aws-lc-sys
crate is C and fails under the NDK — exactly the pain D1 chose Rust
to avoid. Switched to rustls-no-provider + ring, installing the
provider in the constructor so no caller can build a client that
panics on first use.
- ring itself needs CC/AR per target; cargo-ndk sets only the linker.
Added them to the container.
87 tests passing. dr-sync-nextcloud cross-compiles for aarch64-linux-android.
Establishes the v0.1 foundations on both platforms:
- dr-types: SourceRef (never a filesystem path — Android SAF has none),
Format, Availability, Validator with ETag quote normalisation
- dr-gpu: wgpu device, compute pass writing a storage texture, resize
- dr-ui: Slint shell with FR-UI-1 adaptive layout, computed in Rust to
avoid a binding loop
- docker/android: pinned toolchain, verified producing API 28 ARM binaries
Measured the cost of the temporary CPU readback path (dr-gpu bench):
compute is 0.06-0.28ms across sizes while readback is 0.63-7.43ms, so
readback is 90-96% of frame time and scales with area. Recorded in
ARCH §6.1 — this is why spike S1 is the priority.
Mitigations pending S1: reuse the staging buffer, apply at most one
resize per frame, and cap render resolution at 2048 on the long edge.
10 tests passing; core crates cross-compile for aarch64-linux-android.
dtourolle