cheatah-plot

All notable changes to cheatah-plot. This project is alpha — expect breaking changes between releases. Public at github.com/BrofessorDoucette/cheatah-plot; a Biome Standard member alongside the other cheatah extensions.

v0.1.0-alpha (2026-08-14) — figures to pixels: the whole plotting stack, on CPU and GPU

The first release carries the whole arc from the plot.scale seed to rendered PNGs.

The model layers (pure cheatah on ndarray)

• plot.scale grows log-axis geometry (decade log_ticks with 1-2-5 subdivision, to_pixel_log); plot.color (palettes, viridis/magma/coolwarm, a CSS-style name table); plot.series (the mark value + two-arity constructors for all nine mark kinds); plot.stats (histogram binning, the linalg.lstsq fit line, SEM via statistics); plot.figure (subplot grids, axes, the fluent free-function builder).
• Conventions that emerged from the language: two arities instead of default arguments, list<Color> palettes, fluent functions returning modified copies.

The renderer (cheatah-plot's own layer on cheatah-gpu)

• Compute-shader rasterization: ONE Slang source (plot_clear + plot_raster), a 64-byte primitive ABI (segments, discs, rects, triangles, glyphs — the glyph's bitmap rides in the prim), CPU reduce → 16×16 tile binning → per-pixel integer src-over blending. Deterministic by construction.
• Three lanes, one contract: the C++ reference rasterizer is the executable spec; the emulated-Metal lane is BIT-EXACT against it (verified byte-for-byte); the Vulkan lane is tolerance-checked and runs on real hardware and llvmpipe. render() prefers a live GPU lane and falls back to the reference with a one-time notice; CHEATAH_PLOT_FORCE_CPU=1 pins the reference path.
• Dependency-free stored-deflate PNG encoder (+ PPM) and an ORIGINAL 8×16 bitmap font.
• The purr surface: plot.save(fig, path) / plot.render(fig) after building any figure.

Tested and documented to the house bar

• 100% line + function coverage over the package (backend bring-up excluded per the cheatah-gpu-linalg precedent, held instead by the dedicated GPU-lane tests); 78 C++ tests.
• 17 systests through the real runtime — one per plotting FEATURE (every mark kind, styles, grouping, log axes, subplots, legends, fit overlays, PNG save with verified bytes).
• An @par Example block with a complete compilable program on EVERY public function, compile-verified by scripts/check_doc_examples.sh (a hard gate stage).
• 15 example programs render the gallery (examples/purr_plot/run_examples.sh); a Google Benchmark suite covers reduce, binning, raster fill-rate, and PNG encoding.
• The full QA ladder: coverage → docs → module sync → build → systests → biome-install → unit tests → ASan/UBSan → Valgrind → cppcheck → private-refs → doc examples.

Docs

• DESIGN.md and the API outline rewritten to the real architecture: headless first, the renderer on cheatah-gpu's raw forwarders, windowing as a later plot.window layer; the manifest targets the v1.10.0-alpha toolchain and requires cheatah-gpu + cheatah-gpu-linalg.