L03-13g — Measure distance, perimeter, and area on the Quick canvas #238

Outcome

Operators can measure on the page in production units, replacing the retired dimensions plugin.

Parent and boundary

Parent: #231. Owner: LoopEditor. This issue owns one bounded slice of Quick Workspace; consume accepted upstream contracts and keep PDF/verdict/publication authority with Core.

Grounding

• docs/product-surface.json absorbs dimensions-plugin into loop-pages-production.
• No measurement tool exists in LoopEditor or LoopLibQuick; existing measure hits are canvas present metrics.

Acceptance

• Measurement is a tool in the InteractionTool vocabulary and never mutates the document.
• Results respect UserUnit and page rotation and match reference geometry within a stated tolerance.
• Measurements are readable by screen readers and keyboard-operable.
• Failure case: a measurement across a revision change is cleared, not carried to the new geometry.

Required proof

Geometry fixtures with rotation and UserUnit; interaction-controller tests; accessibility smoke. Record the exact source SHA, test command or hosted run, fixture/artifact identity, and any skipped or unavailable lane. Run the repository's mapped proof and check-change gate for a PR.

Handoff

Record changed files, observed result, remaining risk, and a 1–3 sentence anti-slop review. Completion means acceptance evidence, not merely a merged implementation.

Sources

Approved master roadmap · Gap review of docs/loop-shell-actions.json against Quick command handlers, 2026-10-06.