Merging regions united the faces' outlines with a boolean union. Each
face had been refit on its own, so two faces' shared edge could come out
a hair apart: the union then kept the edge between them, or a spur of
it, and a stroked merged shape (unfilled art) showed a stray line inside.
Subtracting the merged shape from the others left slivers along it too.
pathops::FaceMerger merges faces from the planar arrangement itself,
made once per merge: their contours share their edges exactly, so the
edges between merged faces vanish. The Shape Builder builds the merged
shape that way, and what is left of each shape from its faces not merged
(rather than subtracting the merged shape from it). Selections with open
paths keep the old union.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
regions() made one linesweeper contour pass per distinct coverage mask,
and each pass walks the whole arrangement, so finding the regions cost
masks x segments. Two crossing blends make thousands of both: the
Ribbons example's EPS export never finished, and Flatten Transparency,
the Flattener Preview, Divide, Shape Builder and Live Paint slowed down
the same way on dense art.
The masks now go into batches whose faces share no vertex (a greedy
colouring of the masks meeting at each vertex), one contour pass per
batch. A face's contours are walked as in its own mask's pass, since
no other face of the batch touches it; each contour's mask is the one
of its batch at its first point (a vertex of the arrangement), and
contours group under the nearest enclosing contour of the same mask,
as grouped() does in that mask's pass. The regions come out identical,
in the same order.
Fixes#173.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01U9TrG4w49oSRYbP3cqxA3D
Shipped code no longer unwraps, expects or panics: every one of the 124
unwrap()/expect()/panic!/unreachable! sites outside tests now handles the
failure (Result/Option, ?, let-else, defaults) and reports errors to the user.
- Lints: workspace clippy denies unwrap_used, expect_used, panic, todo,
unimplemented and unreachable; clippy.toml allows them in tests, and
integration tests, examples and testkit opt out explicitly.
- Safety net (vectorcraft_engine::guard): a panic in a top-level command rolls
the document back and returns EngineError::Internal; a panicking tool is
reset; the MCP server answers with an internal error and keeps serving; the
UI frame and each control request are guarded.
- APIs that hid failures now return them: Rendered::to_png/to_jpeg/to_webp
return Result (JPEG/WebP errors used to write empty files),
FontDb::face returns Option, Region::top returns Option.
- Fuzzing: engine/tests/import_fuzz.rs feeds garbage, hostile and mutated SVG
and PDF through import → render → export (30k cases locally, no panics).
- Docs: AGENTS.md/CLAUDE.md rule, docs/development.md "Robustness" section,
README pointer and a PR template checklist.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
The sweep compares a curve with another segment over a y-span shorter than
its tolerance by bounding boxes only, so an edge rising by less than that
tolerance (e.g. a rectangle edge cut through a circle's cap, whose computed
intersection end sits ~1e-12 off the horizontal) was mis-ordered and the
result lost a corner: xor/difference/area disagreed by up to 10%. Every
sweep input now snaps on-curve y values within the tolerance to one level
(handles follow and are levelled with their anchor), so such edges become
exact horizontals, which the sweep handles exactly.
- tests/regressions.rs: the six minimal failures found by the properties,
the root cause in isolation, and the self-crossing "star" polygon.
- The star-polygon strategy rejected no angular step of half a turn or
more, so it sometimes drew self-crossing polygons (the shoelace failure).
- Property suites run from a fixed seed (PROPTEST_CASES / PROPTEST_RNG_SEED
still override), so CI cannot fail at random.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
