feat(tinker): add TinkerNativeBackend #532
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added 3 commits
January 23, 2026 07:57
Separate native Tinker training/inference from LocalBackend to keep the API clear while enabling explicit loss/checkpoint behavior and config.
Align tinker native types with OpenAI tooling and update tests to avoid invalid type expressions under pyright.
Use merge_state for backend persistence to avoid clobbering model state, and fail fast on trajectories without Choice objects to prevent no-op training. Expose policy version fields on trajectories for off-policy tracking.
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Summary
TinkerNativeBackendthat implements native Tinker loss/checkpoint flow with renderer-based data conversion and an in-process OpenAI-compatible server.tinkerdependency group (fastapi/uvicorn/tinker/tinker-cookbook) and conditionally export Tinker backends to keep base installs light.LocalBackendmodelbase_pathwith backend path and add an integration test for the Tinker native flow.This is an alternative to #523. That PR tried to combine native Tinker behavior with ART-native behavior in a single backend, which made the code too complex to reason about. Here we split it into a separate native backend. Downside: args are less compatible with
LocalBackend. Upside: we can take advantage of Tinker's functionality more explicitly.Experimental: not yet tested with multi-turn rollouts or tool-calls, but the yes-no-maybe flow converges (avg reward ~0.955 by step 4).
Test plan
uv run pytest tests/integration/test_tinker_native_backend.py -v -s