E01 · F07 · SP-003 — Research for F07

Find, read and record the sources of every story of F07 before its implementation (ADR-0020, research protocol §8).

Acceptance criteria

• Given each story of F07, when the spike ends, then every formula and behavior it needs has a verified REF-* or a DERIV-*.
• Given the sources found, when the spike ends, then the stories' criteria and tasks cite them, and a research note records what was found and what remains open.

Questions

• Placement of a uniformly scaled box in a larger one with nine alignments: a normative source (SVG's preserveAspectRatio and its viewBox transform), and how DERIV-regular-polygon-fit step 5 changes.
• Edges: whether the anchored vertices land exactly on x = 0, x = w, y = 0, y = h in floating point (answer: within rounding, written exactly; note 0005).
• Names of the two settings and of their values (SVG, CSS box alignment, design tools), for the model and the glossary.
• A flat face stays on the anchored side at any radius, a rounded vertex leaves it: what the derivation already proves (step 6, incircle tangent to every side).
• The 3 × 3 anchor picker of design tools, as a functional reference for the playground.

Inventory

Story	Needs
EN-009	placement per alignment, anchored edges; DERIV-regular-polygon-fit step 5
US-009	names of the settings; default; validity; F02 unchanged at center
US-010	3 × 3 picker behavior, keyboard; functional reference
AUD-003	the sources above, re-verified
VAL-003	the check table of DERIV-regular-polygon-fit, anchored rows

Tasks

One task = one commit, referenced as SP-003.Tn.

• T1 — Find, read and record the sources; update the derivation (2 h)
• T2 — Write the research note and update the stories (1 h)