The allocation-free core implements time-based smoothing, dwell selection and strided YUV_420_888 conversion to RGBA. It accepts caller-owned buffers, validates sizes/strides/rotation and handles mirroring explicitly. JNI never retains camera plane pointers. Java owns fixed filter/dwell arrays and reusable direct buffers; there are no exposed native allocation handles to leak or double-free.
The filter shares the desktop Rust implementation's scalar time/reset contract. Invalid or non-finite samples reset it; gaps above 500 ms snap to reacquired input. Dwell activates once per target entry and resets on loss. YUV conversion supports planar and interleaved chroma using each Android plane's row/pixel stride, including padding. The BT.601 limited-range conversion is an inference preprocessing choice, not a color-managed image export pipeline.
Host tests: cmake -S . -B build/host -DZEKALS_SANITIZERS=ON,
cmake --build build/host, ctest --test-dir build/host --output-on-failure.
NDK builds cover arm64-v8a, armeabi-v7a and x86_64. The application library requests
16 KiB page alignment. Third-party native libraries require separate verification.