feat: package Rust OCR bridge in LiteLLM wheel

[ishaan-berri]

What changed

Packages the existing Rust OCR bridge inside the default litellm pip wheel instead of creating a separate Rust wheel package.

• Build backend changes from uv_build to maturin so the PyO3 crate can be built as litellm.rust_bridge._native.
• uv build still works as the build frontend; the previous uv_build source excludes were ported to [tool.maturin].exclude.
• The public wheel/sdist exclude litellm/proxy/enterprise with both the bare directory and recursive /** pattern.
• Docker images install Rust only in builder stages; runtime images do not need Rust/Cargo.
• OCR Rust path remains opt-in and falls back to Python when the native bridge is unavailable.

Related install-report issue: #31261

Why this shape

We looked at the Pydantic/Polars packaging pattern: ship the native Rust extension inside the default Python package, with maturin/PyO3 building platform wheels. That avoids a second LiteLLM package for users while still letting us split the bridge later if needed because Python calls it through litellm.rust_bridge.

Validation

• uv lock
• uv build --sdist --wheel
• Artifact inspection confirmed:
  • wheel includes litellm/rust_bridge/_native...so
  • wheel/sdist include litellm/rust_bridge/loader.py
  • wheel/sdist do not include litellm/proxy/enterprise
• uv run black litellm/rust_bridge litellm/ocr/rust_bridge.py tests/test_litellm/ocr/test_rust_bridge.py
• uv run ruff check litellm/rust_bridge litellm/ocr/rust_bridge.py tests/test_litellm/ocr/test_rust_bridge.py
• uv run pytest tests/test_litellm/ocr/test_rust_bridge.py -q (19 passed)
• (cd litellm-rust && cargo fmt --check && cargo clippy --workspace --all-targets --locked -- -D warnings && cargo test --workspace --locked)
• Main Docker build + import smoke passed
• Non-root Docker build + import smoke passed
• CircleCI using_litellm_on_windows passed after adding Rust to that Windows build job

Review status

• Greptile flagged the missing litellm/proxy/enterprise/** exclude and missing negative-cache in the native loader; both are fixed in the latest commit and covered by artifact inspection/tests.
• Veria AI passed with No security issues found.
• CI is green on the latest PR head.

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[codecov]

Codecov Report

❌ Patch coverage is 90.90909% with 2 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
litellm/rust_bridge/loader.py	87.50%	2 Missing ⚠️

📢 Thoughts on this report? Let us know!

[ishaan-berri]

Requesting fresh bot review on latest head 3ac48285ee40d567c046f9a32321d50c8d14e510.

Greptile findings have been addressed:

• Added litellm/proxy/enterprise/** to [tool.maturin].exclude and artifact-checked that wheel/sdist do not include litellm/proxy/enterprise.
• Added native-bridge negative-cache and a regression test for the missing-extension path.

Veria status on latest head: passing, No security issues found, zero annotations.

@greptile-apps please re-review the latest head.

[ishaan-berri]

@greptile review

approved by mistake

[ishaan-berri]

CI is green on final head ad4dff15f0 after rebasing onto current litellm_internal_staging. The previous flaky llm_responses_api_testing job passed, along with Windows install, pip build, Docker DB image, lint, OSV, and Rust checks.\n\nMerge is currently blocked only by the required BerriAI/litellm-engineering approval rule after the rebase/lockfile fix refreshed the head commit.