Android fd backed shm

.bazelrc

@@ -42,6 +42,7 @@ build:macos_x86_64 --extra_execution_platforms=//platform/host:darwin_x86_64
 
 # For all builds, use C++17
 build --cxxopt="-std=c++17"
+build --java_runtime_version=remotejdk_17
 
 # Statically link C++ deps into Rust binaries (avoids RPATH issues)
 build --@rules_rust//rust/settings:experimental_use_cc_common_link=True
@@ -97,6 +98,10 @@ build:android_arm64 --cpu=aarch64
 build:android_arm64 --linkopt=-lc++_static
 build:android_arm64 --linkopt=-lc++abi
 build:android_arm64 --extra_toolchains=@androidndk//:all
+# Abseil strips flag names on Android by default (ABSL_FLAGS_STRIP_NAMES=1),
+# which breaks parsing flags by name (e.g. --socket) on the command line even
+# though GetFlag() still works.  Keep the names so server/tool flags work.
+build:android_arm64 --copt=-DABSL_FLAGS_STRIP_NAMES=0
 
 build:android_x86_64 --platforms=//platform/android:android_x86_64
 build:android_x86_64 --action_env=ANDROID_NDK_HOME
@@ -105,6 +110,8 @@ build:android_x86_64 --cpu=x86_64
 build:android_x86_64 --linkopt=-lc++_static
 build:android_x86_64 --linkopt=-lc++abi
 build:android_x86_64 --extra_toolchains=@androidndk//:all
+# See android_arm64 note above.
+build:android_x86_64 --copt=-DABSL_FLAGS_STRIP_NAMES=0
 
 build:android --config=android_arm64
 

.cursor/skills/subspace-builds/SKILL.md

@@ -0,0 +1,144 @@
+---
+name: subspace-builds
+description: Build and test Subspace across supported platforms and build systems. Use when the user asks how to build, test, cross-compile, run CI-equivalent checks, or work with Bazel, CMake, Android, Soong/Blueprint, AOSP, QNX, Linux, or macOS builds in this repository.
+---
+
+# Subspace Builds
+
+## General Rules
+
+- User-facing examples should use `bazel`; use `bazelisk` as a drop-in
+  replacement if `bazel` is not available.
+- Prefer focused targets while iterating; use `bazel test //...` only when
+  broad verification is needed.
+- Check `.bazelrc`, `.github/workflows/ci.yml`, and `docs/android.md` before changing platform build behavior.
+- Do not check in generated protobuf files.
+
+## Native Host Builds
+
+Linux:
+
+```bash
+CC=clang bazel build //...
+bazel test //...
+
+cmake -S . -B build/cmake-Debug -DCMAKE_BUILD_TYPE=Debug
+cmake --build build/cmake-Debug --parallel
+ctest --test-dir build/cmake-Debug --output-on-failure
+```
+
+macOS Apple Silicon:
+
+```bash
+bazel build //... --config=macos_arm64
+bazel test //... --config=macos_arm64
+```
+
+macOS Intel:
+
+```bash
+bazel build //... --config=macos_x86_64
+bazel test //... --config=macos_x86_64
+```
+
+## Android With Bazel
+
+Requires `ANDROID_NDK_HOME`.
+
+```bash
+bazel build \
+  //server:subspace_server \
+  //client:client_test \
+  //c_client:client_test \
+  //plugins:nop_plugin.so \
+  //plugins:split_buffer_free_test_plugin.so \
+  //android/jni:libsubspace_jni.so \
+  //android/java:subspace-java \
+  //android/java:subspace-java-test \
+  --config=android_arm64
+```
+
+Use `--config=android_x86_64` for x86_64 emulators and GitHub CI. The emulator
+deployment and test flow is in `.github/scripts/android-test.sh`.
+
+## Android With CMake
+
+Requires `ANDROID_NDK_HOME`. Build a host `protoc` first and pass it into the
+Android cross-compile so protobuf versions match:
+
+```bash
+cmake -S . -B build/host-protoc -DCMAKE_BUILD_TYPE=Release
+cmake --build build/host-protoc --target protoc --parallel
+
+cmake -S . -B build/android \
+  -DCMAKE_TOOLCHAIN_FILE=$ANDROID_NDK_HOME/build/cmake/android.toolchain.cmake \
+  -DANDROID_ABI=arm64-v8a \
+  -DANDROID_PLATFORM=android-28 \
+  -DANDROID_STL=c++_shared \
+  -DCMAKE_BUILD_TYPE=Release \
+  -DPROTOC_EXECUTABLE="$PWD/build/host-protoc/_deps/protobuf-build/protoc"
+
+cmake --build build/android --parallel
+```
+
+Use `-DANDROID_ABI=x86_64` for x86_64 emulators and GitHub CI. The emulator
+deployment and test flow is in `.github/scripts/cmake-android-test.sh`.
+
+## Android With Soong/Blueprint
+
+Soong requires a full AOSP checkout; GitHub-hosted runners do not provide one.
+Use a local AOSP tree or a self-hosted runner with AOSP already synced.
+
+Place this repository at `external/subspace`, ensure `external/coroutines` and
+`external/cpp_toolbelt` are present, and copy their repository-provided
+`Android.bp.example` files to `Android.bp`.
+
+Add to the product:
+
+```make
+PRODUCT_SOONG_NAMESPACES += external/subspace
+PRODUCT_PACKAGES += \
+    subspace_server \
+    libsubspace_client \
+    libsubspace_jni \
+    subspace-java \
+    subspace_java_client_test
+```
+
+Build from AOSP root:
+
+```bash
+source build/envsetup.sh
+lunch <product>-userdebug
+
+m external.subspace-subspace_server-soong \
+  external.subspace-libsubspace_client-soong \
+  external.subspace-libsubspace_jni-soong \
+  external.subspace-subspace-java-soong \
+  external.subspace-subspace_java_client_test-soong
+```
+
+Run the device-side Java integration test:
+
+```bash
+adb shell subspace_java_client_test
+```
+
+## QNX With Bazel
+
+Requires the QNX SDP and `QNX_SDP_PATH`.
+
+```bash
+bazel build //... --config=qnx_aarch64
+bazel build //... --config=qnx_x86_64
+```
+
+If the default path in `.bazelrc` is wrong, set `QNX_SDP_PATH` in the
+environment or user-local `user.bazelrc`.
+
+## References
+
+- Android details: `docs/android.md`
+- General Bazel/CMake docs: `README.md`
+- CI build matrix: `.github/workflows/ci.yml`
+- Test runner rule: `.cursor/rules/test-runner.mdc`