vernier 0.0.1

High-performance, parity-preserving COCO-style evaluation

vernier

High-performance, parity-preserving COCO-style evaluation for object detection, instance segmentation, and keypoints. Rust core, Python frontend, optional CLI.

Status: early development. Public API is unstable and the project is pre-1.0. See docs/adr/ for the design decisions that are shaping it.

Why vernier

Existing COCO evaluation tooling presents a forced choice: the reference pycocotools is correct-by-definition but slow and unmaintained; faster reimplementations exist but each comes with its own drift from the reference. vernier aims to provide a single library that is:

• Bitwise identical to the pycocotools reference on the minimal API
• Fast — Rust core, SIMD-friendly data layout, zero-copy on the hot path
• Honest about quirks — extended API offers corrected definitions alongside the reference, with the difference documented per-quirk
• Embeddable — pure-Rust core usable from CLI, ROS2 nodes, or any other Rust program without dragging Python along

Layout

crates/
  vernier-core/   pure Rust evaluation logic; no Python dependency
  vernier-ffi/    PyO3 bindings; data conversion only, no business logic
python/
  vernier/        thin Python wrapper; the user-facing API lives here
docs/
  adr/            Architecture Decision Records
  ...             Diátaxis-organized documentation
tests/
  rust/           Rust integration tests
  python/         Python tests against the FFI boundary

Quickstart (development)

Prerequisites: Rust stable, uv, just, and cargo-nextest.

# One-time setup
just bootstrap

# Iterate
just develop      # fast incremental rebuild
just test         # Rust + Python tests
just lint         # clippy + ruff + pyright (read-only, CI-equivalent)
just fmt          # auto-format everything

Project governance

Architectural decisions are recorded in docs/adr/. The first ADR (0001-record-architecture-decisions.md) establishes the process itself. Significant changes — anything that affects the public API, the FFI boundary, or the parity contract — start as an ADR draft.

License

Dual-licensed under either of Apache License, Version 2.0 or MIT license at your option.