E01 · F01 · EN-001 — Write numbers with fixed precision

Write a derived number in SVG output with at most SVG_DECIMALS = 5 decimals (Q10), for every path coordinate of F01.

Acceptance criteria

• Given 1, when written, then the output is 1 (integers stay integers).
• Given 1 / 3, when written, then the output is 0.33333.
• Given 86.602540378, when written, then the output is 86.60254.
• Given 2.5000000001, when written, then the output is 2.5 (no trailing zeros, Product Owner 2026-10-08).
• Given -0.000001, when written, then the output is 0 (never -0, Product Owner 2026-10-08).

Tasks

One task = one commit, referenced as EN-001.Tn.

• T1 — Write the tests of the cases above, values computed by hand (1 h)
• T2 — Add the SVG_DECIMALS constant module in src/io/ (0.5 h) — svg-decimals.ts
• T3 — Implement the number formatting function (format) with its TSDoc and @see REF-SVG2-PATHS (1.5 h) — formatSvgNumber
• T4 — Record the precision rule in docs/domain/shapes.md §1 if anything changes (0.5 h)