imazen/imageflow

# Imageflow Project Instructions

## SIMD & Dispatch Crates

`multiversion` is allowed in this project for autovectorization dispatch on scalar loops (e.g., `scaling.rs`). Prefer the defaults provided by `multiversed` for new code — use `multiversion` only where `multiversed` doesn't fit.

For explicit SIMD intrinsics, use `archmage` (already in use for `transpose.rs`).

## f32/f64 Clamping

**Do NOT replace `min(max(...))` patterns with `.clamp()` on floats.** `f32::clamp()` propagates NaN, while `min(max(...))` suppresses it. In image processing pipelines, NaN propagation turns a single bad pixel into a full-image corruption. The `min(max(...))` pattern is intentional NaN defense.

## Git Workflow

Always commit `cargo fmt` changes as a separate commit from code changes.

## Test Commands

All integration tests live in `imageflow_core/tests/integration/` as a single binary.

```bash
just test              # run all tests with nextest
just test-filter NAME  # run tests matching NAME
just test-update       # run tests, auto-accept checksums within tolerance
just test-replace      # reset all checksum baselines to current output
just test-list         # list all test names
just test-build        # compile-check tests without running
```

Checksum TOML files: `imageflow_core/tests/visuals/checksums/`
Reference images: `imageflow_core/tests/visuals/checksums/images/`

## Known Bugs

## Delayed TODOs

- **Licensing/caching module** (`imageflow_helpers/src/unused/`): ~2300 lines of draft licensing, caching, and polling code. Currently unreferenced (no `mod` declaration). Needs review, modernization, and wiring into the build when ready to complete.