Rename StreamProxy helper to LiteRtLmBridge

[leehack]

Summary

• Rename the downstream helper concept from StreamProxy to LiteRtLmBridge in docs and packaging scripts.
• Move the helper source to native/bridge/litert_lm_bridge.c and keep the exported stream_proxy_* symbols unchanged for downstream ABI compatibility.
• Add a repo-owned native/bridge/BUILD.bazel package that defines the shared LiteRT-LM runtime targets with embedded bridge symbols.
• Make tools/build_upstream_runtime.py build //bridge:* through Bazel --package_path=<repo native dir>:<upstream source>, so source-built runtimes no longer copy files into upstream or edit upstream c/BUILD, WORKSPACE, or patch files.
• Replace existing staged artifacts by unlinking before copy so read-only local runtime files do not break rebuilds.
• Refresh docs/current_upstream.md to the latest upstream v0.13.1 metadata reported by the repo tooling.

Validation

• macOS arm64 local source build:
  • python3 tools/build_upstream_runtime.py --upstream-tag local --platform macos --arch arm64 --source-root /opt/UnitySrc/personal/llama/LiteRT-LM-text-lora-resource-manager --jobs=4
  • Built //bridge:libLiteRtLm.dylib through --package_path.
  • Validated LiteRT-LM C API plus stream_proxy_* bridge symbols.
  • Staged bin/macos/arm64/libLiteRtLm.dylib.
• macOS x64 local source build:
  • python3 tools/build_upstream_runtime.py --upstream-tag local --platform macos --arch x64 --source-root /opt/UnitySrc/personal/llama/LiteRT-LM-text-lora-resource-manager --jobs=4
  • Built and linked //bridge:libLiteRtLm.dylib through --package_path.
  • Validated LiteRT-LM C API plus stream_proxy_* bridge symbols.
  • Staged bin/macos/x64/libLiteRtLm.dylib.
• Android arm64 local source build with NDK r28c:
  • ANDROID_NDK_HOME="$HOME/Library/Android/sdk/ndk/28.2.13676358" python3 tools/build_upstream_runtime.py --upstream-tag local --platform android --arch arm64 --source-root /opt/UnitySrc/personal/llama/LiteRT-LM-text-lora-resource-manager --jobs=4
  • Built and linked //bridge:libLiteRtLm.so through --package_path.
  • Validated LiteRT-LM C API plus stream_proxy_* bridge symbols.
  • Staged libLiteRtLm.so, libGemmaModelConstraintProvider.so, and libLiteRt.so.
• Android x64 local source build with NDK r28c:
  • ANDROID_NDK_HOME="$HOME/Library/Android/sdk/ndk/28.2.13676358" python3 tools/build_upstream_runtime.py --upstream-tag local --platform android --arch x64 --source-root /opt/UnitySrc/personal/llama/LiteRT-LM-text-lora-resource-manager --jobs=4
  • Built and linked //bridge:libLiteRtLm.so through --package_path.
  • Validated LiteRT-LM C API plus stream_proxy_* bridge symbols.
  • Staged libLiteRtLm.so, libGemmaModelConstraintProvider.so, and libLiteRt.so.
• Linux arm64 Docker source build:
  • docker run --platform linux/arm64 ... python3 tools/build_upstream_runtime.py --upstream-tag local --platform linux --arch arm64 --source-root /work/LiteRT-LM --jobs=4 && python3 tools/validate_runtime_dependencies.py
  • Built and linked //bridge:libLiteRtLm.so through --package_path from a container-local copy of both repos.
  • Validated LiteRT-LM C API plus stream_proxy_* bridge symbols.
  • Staged libLiteRtLm.so, libGemmaModelConstraintProvider.so, and libLiteRt.so in the container copy.
  • Dependency validation passed for 3 ELF libraries.
• Linux x64 Docker source build under linux/amd64 emulation:
  • docker run --platform linux/amd64 ... python3 tools/build_upstream_runtime.py --upstream-tag local --platform linux --arch x64 --source-root /work/LiteRT-LM --jobs=4 && python3 tools/validate_runtime_dependencies.py
  • Built and linked //bridge:libLiteRtLm.so through --package_path from a container-local copy of both repos.
  • Validated LiteRT-LM C API plus stream_proxy_* bridge symbols.
  • Staged libLiteRtLm.so, libGemmaModelConstraintProvider.so, and libLiteRt.so in the container copy.
  • Dependency validation passed for 3 ELF libraries.
• llamadart macOS arm64 consumer smoke using the locally staged PR runtime:
  • LLAMADART_LITERT_LM_LIB_DIR=/opt/UnitySrc/personal/llama/litert-lm-native/bin/macos/arm64 dart run tool/litert_lm_engine_smoke.dart /opt/UnitySrc/personal/llama/LiteRT-LM-text-lora-resource-manager/runtime/testdata/test_lm.litertlm cpu 'What is 2+2? Answer only with the number.' 4 1024
  • Loaded the PR-built libLiteRtLm.dylib, initialized the LiteRT-LM CPU backend, loaded a .litertlm model fixture, tokenized/detokenized, and streamed 4 generated tokens through llamadart.
• python3 tools/validate_runtime_dependencies.py passed in the host checkout for the locally staged Android ELF libraries.
• python3 -m py_compile tools/runtime_dependency_utils.py tools/fetch_upstream.py tools/build_upstream_runtime.py tools/package_release.py tools/validate_artifacts.py tools/package_upstream_prebuilts.py tools/package_official_release_assets.py tools/package_ios_runtime.py tools/package_apple_xcframeworks.py tools/validate_runtime_artifacts.py tools/validate_runtime_dependencies.py tools/validate_release_manifest.py
• cc -std=c11 -Wall -Wextra -fsyntax-only native/bridge/litert_lm_bridge.c
• node web/src/index.js --self-test
• python3 tools/package_release.py --upstream-tag v0.12.0 && python3 tools/validate_artifacts.py completed with the local artifact cache; generated metadata was restored because artifact-cache churn is not part of this PR.
• Temporary prebuilt packaging probe for v0.13.1 in a throwaway repo copy:
  • python3 tools/package_upstream_prebuilts.py --upstream-tag v0.13.1 --clean
  • Copied 38 upstream prebuilt files.
  • rg "version https://git-lfs.github.com/spec/v1" bin -S found 0 Git LFS pointer files.
• python3 tools/fetch_upstream.py --latest --metadata-only resolved upstream v0.13.1 and was used to refresh docs/current_upstream.md.
• git diff --check

Not run:

• Windows source build. This still needs GitHub Actions or a Windows machine.
• Full release-artifact completeness validation in this host checkout. python3 tools/validate_runtime_artifacts.py --upstream-tag v0.13.1 currently fails locally because the Linux Docker artifacts were intentionally isolated from the host checkout, the Windows runtime is absent, and dist/official/v0.13.1/CLiteRTLM.xcframework.zip is not staged locally.
• iOS source build is not applicable to this bridge change; the repo packages iOS from upstream official CLiteRTLM.xcframework assets.