Drawing an outline by hand for every frame of a sheet is slow, and the outline mostly follows the opaque part of the image anyway. The texture tab now traces it: one click, a corner budget, and every Frame collision collider and tile using that frame blocks with the result. - "Generate collision..." sits in the texture tab header and is off while the texture has no frames. - The dialog has Max points (default 8, 3 to 64), Solid from ... % alpha (default 50) and All frames of the texture. A live line says what Generate will write, and Generate stays off when nothing is solid enough. - traceCollision walks each island of solid pixels along the pixel edges, then drops the least important corners until at most N are left and no stair step remains. A slope becomes one straight edge. - An outline never crosses itself. Where the image would force that, the island's convex hull is taken instead. - Crumbs under 1 % of the frame area are dropped unless they are the only island. Holes are not reproduced. - Existing outlines are replaced. One frame or all frames is a single undo step. - TextureLibrary hands out the sheet's RGBA data, and a pure function cuts a frame's region from it. Findings: - The wedge in the e2e fixture gets 4 corners, not 3. Its tip is one pixel wide in the image, and that real edge stays while corners are still free. Tests: - ./check.sh: 131 files, 1941 tests, CHECK EXIT 0 (was 130 / 1931). - 10 new unit tests in tests/core/trace-collision.test.ts, including 150 random shapes that must all be valid and within the budget. - GM_STEPS=42, freshly seeded: ALL PASSED, 20 checks (was 16). - Three counter-probes bite: no hull fallback, no stair threshold, dialog ignoring the alpha threshold. - Check sum 1202 in README is computed (1198 + 4), CI measures it. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>