DataFusion FFI Skill

This crate exposes a stable C ABI for DataFusion traits so that independently-compiled libraries (different Rust versions, plugins, datafusion-python, etc.) can interoperate at runtime. Stability and correctness here are load-bearing: a missed pattern can cause segfaults, leaks, or silently dropped trait behavior on the consumer side.

Read the crate's README.md first if you have not — it establishes the vocabulary (FFI_X / ForeignX, library_marker_id, release, TaskContextProvider, stabby vs #[repr(C)]).

When to use

Trigger this skill any time the work touches datafusion/ffi/:

• Adding a new FFI_<Trait> + Foreign<Trait> pair
• Adding a method to an existing FFI_X struct
• Reviewing a PR that touches this crate
• Changing the codec / proto serialization layer
• Bumping the wrapped DataFusion trait surface (e.g. a new default method appeared upstream)

Hard rules