[hellovai]

Changes

• publish crates/bridge_cffi/include/baml_cffi.h as the canonical C/C++ contract for baml_get_api_v1
• make Rust ABI declarations authoritative via pinned, deterministic cbindgen generation and checked-in drift tests
• document practical ownership, lifetime, threading, panic, and V1 evolution rules next to the public declarations
• verify enum widths/discriminants, structure size/alignment/offsets, table order, function signatures, and calling conventions from Rust, C11, and C++17
• add C and C++ dynamic-loader smoke consumers that resolve only baml_get_api_v1, validate the table, call version, and release its buffer
• run the public-header smoke in the existing bridge CFFI release workflow on Linux, macOS, and Windows/MSVC

Testing

• cargo fmt --all --check
• cargo test -p bridge_cffi
• cargo clippy -p bridge_cffi --all-targets -- -D warnings
• cargo check -p bridge_cffi --target wasm32-unknown-unknown
• strict C11 and C++17 compile/layout tests
• macOS C and C++ runtime smoke against libbridge_cffi.dylib
• repository pre-commit hooks

Summary by CodeRabbit

• New Features
  • Introduced a stricter, versioned public C/C++ ABI contract with explicit ABI versioning, compatibility validation, and a typed function-table surface (including updated exported naming and stable enum discriminants).
• Tests
  • Added compile-time ABI assertions, cross-language ABI layout verification, deterministic public header generation checks, and a new ABI smoke test that dynamically loads a bridge and validates required entrypoints.
• Documentation
  • Clarified FFI buffer ownership/release expectations and expanded ABI/status documentation.
• CI / Chores
  • Updated ABI smoke workflow to use the new runner and removed the legacy smoke script; standardized test runs on Windows to suppress profiling output.

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Project	Deployment	Actions	Updated (UTC)
beps	Ready	Preview, Comment	Jul 16, 2026 9:36am
promptfiddle	Ready	Preview, Comment	Jul 16, 2026 9:36am
promptfiddle2	Ready	Preview, Comment	Jul 16, 2026 9:36am

[github-actions]

⏭️ Performance benchmarks were skipped

Perf benchmarks (CodSpeed) are opt-in on pull requests — they no longer run on every push. They always run automatically after merge to canary/main.

To run them on this PR, do any of the following, then push a commit (or re-run CI):

• Add RUN_CODSPEED=1 to the PR description, or
• Include run-perf or /perf in the PR title or any commit message.

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📝 Walkthrough

Walkthrough

The bridge CFFI surface now has a generated versioned C/C++ ABI header, explicit Rust callback and function-pointer types, cross-language layout assertions, deterministic header checks, and dynamic smoke tests that resolve baml_get_api_v1 and verify the product version. The Windows standard test workflow also disables incidental profiling output.

Changes

CFFI ABI contract and validation

Layer / File(s)	Summary
Versioned ABI contract and generated header baml_language/{Cargo.toml,crates/bridge_cffi/Cargo.toml}, baml_language/crates/bridge_cffi/{cbindgen.toml,include/baml_cffi.h,src/api.rs}	Defines the versioned append-only API table, public enums, callback types, export rules, calling conventions, and generated header contract.
Rust ABI wiring and ownership contracts baml_language/crates/bridge_cffi/src/{buffer.rs,lib_native.rs}, baml_language/crates/bridge_cffi/src/ffi/*	Aligns callback re-exports and host-release signatures, expands public exports, and documents buffer, status, and bridge metadata boundary rules.
C and C++ ABI layout validation baml_language/crates/bridge_cffi/tests/{abi_assertions.h,abi_layout.*,header_generation.rs}	Adds compile-time and runtime checks for ABI widths, discriminants, field layouts, function-pointer types, generated-header determinism, and Rust representation attributes.
Header-based dynamic smoke flow baml_language/crates/bridge_cffi/tests/{abi_smoke.c,run_abi_smoke.py}, .github/workflows/build2-bridge-cffi.reusable.yaml	Builds C11/C++17 consumers, loads the shared library, validates the API table, calls version(), and compares both observed versions with release-plan.json.

Windows test profile

Layer / File(s)	Summary
Disable default profiling output .github/workflows/cargo-tests.reusable.yaml	Sets BAML_PROFILE to 0 for the standard Windows cargo test step and documents the profiling behavior.

Estimated code review effort: 4 (Complex) | ~60 minutes

Possibly related PRs

• BoundaryML/baml#4033 — Changes the same workflow’s shared-library smoke testing.
• BoundaryML/baml#4037 — Replaces the legacy ctypes smoke invocation.
• BoundaryML/baml#4041 — Establishes the related versioned bridge ABI foundation.

Sequence Diagram(s)

sequenceDiagram
  participant SmokeRunner
  participant CConsumer
  participant CppConsumer
  participant BridgeLibrary
  SmokeRunner->>CConsumer: compile and execute public-header consumer
  SmokeRunner->>CppConsumer: compile and execute public-header consumer
  CConsumer->>BridgeLibrary: resolve baml_get_api_v1
  CppConsumer->>BridgeLibrary: resolve baml_get_api_v1
  BridgeLibrary-->>CConsumer: return compatible BamlApiV1
  BridgeLibrary-->>CppConsumer: return compatible BamlApiV1
  CConsumer->>BridgeLibrary: call version and free buffer
  CppConsumer->>BridgeLibrary: call version and free buffer
  SmokeRunner-->>SmokeRunner: compare observed versions with expected version

Loading

Poem

I’m a rabbit with headers, hopping ABI-wide,
C and C++ consumers now run side by side.
Tables stay ordered, versions ring true,
Buffers are freed as they’re meant to do.
baml_get_api_v1 leads the way—
Hop, compile, smoke, and yay! 🐇

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 18.75% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly summarizes the main change: publishing the generated V1 C ABI for bridge_cffi.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch codex/public-cffi-abi

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[github-actions]

Binary size checks passed

✅ 7 passed

	Artifact	Platform	File	Gzip	Gated on	Baseline	Delta	Status
✅	baml-cli	Linux	🔒 22.8 MB	9.7 MB	file	22.8 MB	+66.0 KB (+0.3%)	OK
✅	packed-program	Linux	🔒 16.3 MB	6.8 MB	file	16.3 MB	+24.6 KB (+0.2%)	OK
✅	baml-cli	macOS	🔒 17.6 MB	8.5 MB	file	17.5 MB	+49.7 KB (+0.3%)	OK
✅	packed-program	macOS	🔒 12.6 MB	6.0 MB	file	12.6 MB	+32 B (+0.0%)	OK
✅	baml-cli	Windows	🔒 19.2 MB	8.7 MB	file	18.7 MB	+425.5 KB (+2.3%)	OK
✅	packed-program	Windows	🔒 13.5 MB	6.1 MB	file	13.5 MB	+5.6 KB (+0.0%)	OK
✅	bridge_wasm	WASM	15.2 MB	🔒 4.3 MB	gzip	4.3 MB	+4.6 KB (+0.1%)	OK

🔒 = the size this artifact is GATED on (ceiling + delta). Binaries gate on file size (installed binary); WASM gates on gzip (download size). The other size is shown for information only.

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Generated by cargo size-gate · workflow run