editor

0010 — Sources of F10: round shape ​

Spike SP-008, 2026-10-12. Claude Code's own research; every source below was read.

The capsule (EN-016) ​

  • A rectangle capped by two half circles is a stadium (also discorectangle, obround) (REF-MATHWORLD-STADIUM). The project calls it a capsule in plain words.
  • Rounding every corner of the box by half its smaller side gives it exactly: on the short sides the two setbacks fill the side, on the long sides a straight part remains, and no radius is reduced (DERIV-round-shape step 1, from DERIV-local-radius-clamp). SVG does not draw a capsule from a rect: it caps rx at half the width and ry at half the height separately (REF-SVG2-SHAPES §10.2), so a 120 × 80 rect with a large radius has elliptical corners. Figma's rounded rectangle at its maximal radius was not read; the derivation does not need it.
  • No new geometry: the round shape's corners go through roundedContour, as every shape.

Conversion (EN-016, US-020) ​

  • Integer radii of half the smaller side rounded up draw the same shape: an odd side is reduced to exactly its half by the clamp (DERIV-round-shape step 2; in floating point 40.50000000000001: tests use a tolerance). The free shape is the rectangle tool's for the box, valid at a size of 0.

Model (EN-016) ​

  • A shape of its own (draft ADR-0036, accepted on the feature branch, never on main): kind: "round", width, height, angle, position; one function tells the three shapes apart. The playground's tests of "anchor" in model take a shape without anchor for a free shape: US-020 replaces them (read-edited-free-shape, show-point-fields, show-delete-button, show-point-buttons, mount-playground, create-box-elements, listen-to-point-fields, shape-reading).

Archive: F10 cancelled in E01 (2026-10-12) ​

F10 was built up to its audit, then cancelled at its validation (VAL-008), and moved to E14 by the Product Owner. None of its code reached main. It is kept for E14:

  • The code: the Git tag archive/f10-round-shape holds the last state of the validation branch (code, tests, draft ADR-0036, stories, guided test steps 58 to 64, demo page f10-round-shape.md). The pull requests into the feature branch keep each story's diff: SP-008 (#134), EN-016 (#135), CHK-008 (#136), US-020 (#138), AUD-008 (#139).
  • The model (src/model/): RoundShape (kind: "round", width, height, angle, position), isValidRoundShape, roundShapeCorners (the box rounded by half its smaller side), roundShapeAsFreeShape (the rectangle tool's free shape, radii rounded up), shapeKind and isFreeShape (three kinds of shape told apart), shapeAsFreeShape and isConvertible (one rule for converting a polygon or a round shape).
  • The playground: a "Round" choice; read-shape split by kind (read-polygon-shape, read-rectangle-shape, read-round-shape); the radius fields hidden for a round shape; the tests of "anchor" in model replaced by isFreeShape, which E14 can reuse for any new kind of shape.
  • Lessons from the reviews: a derived radius must not leak into the next shape's fields; a degenerate shape (width 0) must stay convertible; a rule used in two places is written once.

Validation (VAL-008, 2026-10-12) ​

  • Steps 58 to 64: no other remark.
  • Product Owner decision: a round shape in a long box is an ellipse, as in Figma and Inkscape, not a capsule — a capsule is what a rectangle with a very large radius gives; this replaces the refinement's choice of the capsule.
  • A converted round shape should also offer points on the curve, at its top, right, bottom and left, with handles as in Figma, besides the 4 corners of its box.
  • Ellipses and curves with handles are outside ADR-0001 (Q4), and the subject is too large for E01: the round shape, the ellipse and Bézier curves with handles make epic E14; text (F05) makes epic E15; E01 ends with F06.

Open ​

For E14's first spike: the questions listed in the epic.