E01 · F03 · SP-004 — Research for F03

Find, read and record the sources of every story of F03 before its implementation (ADR-0020, research protocol §8).

Acceptance criteria

• Given each story of F03, when the spike ends, then every 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

• Clamping with a different radius at each corner: whether DERIV-local-radius-clamp already covers it (each edge shares its length between its two corners in proportion to their setbacks), and hand-computed cases.
• The model of a radius per vertex: one array of requested radii, its length tied to the number of vertices; whether this is a structural decision (ADR).
• A mixed value in a properties panel (Figma "Mixed"), as a functional reference.
• Selecting several items in a list (range with Shift, toggle with Ctrl / Cmd) and on a drawing: WAI-ARIA listbox pattern, design tools.
• Node handles and the start and direction of a path in design tools (Inkscape node tool), as a functional reference.

Inventory

Story	Needs
EN-010	clamping with unequal radii; model of the radii
US-011	mixed value; radii kept by vertex number
US-012	node handles, first and second vertex marked
US-013	multiple selection in a list and on a drawing
AUD-004	the sources above, re-verified
VAL-004	the check table of the clamp derivation, unequal radii rows

Tasks

One task = one commit, referenced as SP-004.Tn.

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