[chrisuthe]

Adds android, a client-only implementation backed by SendspinDroid. This is the first of four steps toward replacing the sendspin-jvm client; sendspin-jvm stays until the last one. Part of Sendspin/backlog#70.

What changes

• Adapter (adapters/android/client/): a Kotlin/JVM Gradle project, ported from SendspinDroid's own conformance-client.
  • It builds SendspinDroid's Kotlin Multiplatform :shared module from repos/SendspinDroid through a composite build, using the clone's own Gradle wrapper.
  • It runs on the app's handshake driver, Noise wire codec, MessageBuilder and MessageParser.
  • It is launched as a fat jar by src/conformance/adapters/android_client.py.
• Advertised formats: client/hello comes from the app's MessageBuilder.buildSupportedFormats, not a hand-written list.
  • The scenario's preferred codec is the app's preferred-codec input.
  • Bit depths are those of an API 31+ device: 48 kHz stereo and mono PCM at 32, 24 and 16 bits, behind the one preferred compressed codec.
• Format preference: the preferred format is sent in every client/state once set, as the app's protocol handler does.
• Evidence:
  • PCM is hashed from the decrypted frames.
  • FLAC and OPUS are decoded only by Android MediaCodec, so the adapter reports encoded hashes and the codec header, and decoded audio is not judged.
• Build: _gradle_build_result now takes the adapter and repository, so sendspin-jvm and android share it.
• Report links: repository_versions.py takes each implementation's link from the registry's remote_url instead of assuming the Sendspin organization. Every existing row's link is unchanged; android links chrisuthe/SendspinDroid.
• CI: publish.yml adds android to the client list and installs JDK 21 alongside 17. The macos-26 image already provides ANDROID_HOME with android-36, which SendspinDroid's Gradle settings need to configure.

Results

Run locally against aiosendspin and sendspin-server-cpp:

Scenario	Result	Cause
client-initiated-state-format-pcm	passes on both	Renegotiates from 32-bit to 16-bit PCM.
client-initiated-pcm	fails on both, PCM hash mismatch	The app advertises 48 kHz only and the fixture is 8 kHz mono, so the server resamples and the canonical hash cannot match. This follows from what the app advertises, not from the harness.
client-initiated-state-format-flac	fails on both	The app lists its preferred codec ahead of PCM and offers no other codec, so it cannot advertise the PCM-then-FLAC order the scenario starts from. The adapter still takes part, then fails with that reason. Tracked in chrisuthe/SendspinDroid#336.

Known differences from the app

• The adapter drives :shared with its own session logic, because the app's SendSpinProtocolHandler lives in the Android-bound :player module.
• As a result it reports available: true straight after activation, where the app waits for clock sync.