vtracer/docs/design/roadmap.md

Roadmap and Verification

Milestones

Each milestone leaves the repo building and tested.

1. Scaffold — new workspace (crates/vtracer-core, crates/vtracer); IR + stage traits; port the existing stacked pipeline behind them, behavior-identical; golden-SVG snapshot tests over the sample images; CLI ported to clap 4 (range validation via value_parser, no more panic!).
2. Writer + optimizer — VectorDoc writer with relative/shorthand encoding, QuantizePass, SimplifyPass; byte-size benchmark vs the 0.6.x output; rasterize-and-diff regression (resvg) proving visual equivalence.
3. Color fitting — FixedPalette (OKLab nearest) + AutoQuantize + adjacent-region merge; --palette / --palette-file CLI.
4. Mosaic — boundary-graph module + open-polyline fitting (see mosaic.md); --hierarchical cutout switched to the true mosaic; full unit/property test suite.
5. Bindings — pyo3 port, vtracer-wasm, the npm package under nodejs/; delete webapp/; CI covers crates.io + PyPI + npm releases.

Verification strategy

• Unit — hand-crafted label maps for mosaic (checkerboard, T-junction, nested islands, border-touching, self-loops); fitter round-trips; writer encoding cases.
• Snapshot — golden SVGs for the sample images per preset/mode; asserted byte-size budget for the optimizer.
• Property (proptest) — mosaic invariants: every boundary edge used exactly twice; shoelace area == pixel counts; PixelFitter rasterize round-trip is byte-identical to the label map; fitted deviation ≤ 0.5 px budget; endpoints exact on lattice nodes.
• Visual — rasterize output with resvg; pixel-diff/SSIM against the input (thresholded) and against pre-rewrite output for stacked mode; mosaic diffs confined to a ~1-px boundary band.
• Targets — cargo build --target wasm32-unknown-unknown -p vtracer-core -p vtracer-wasm; maturin build with python-binding; npm test in nodejs/.