F14.2 — Guided canvas: numbered overlay and palette guidance

[Flow-Fly]

Parent: #128. Depends on the durable guide produced by #129.

Product contract

Guided mode helps an artist draw; it does not grade or reject their choices. The target buffer supplies numbers, palette suggestions, highlights, and optional comparison information.

Recipe

1. Guided project state

   • Read the durable guide from the active project context.
   • Lock mutations that would invalidate guide coordinates or numbering: palette editing, layer/frame structure changes, resize, and destructive project transforms.
   • Keep pencil, eraser, undo, redo, pan, zoom, touch pinch, and zoom-to-fit available.

2. Numbered overlay

   • Render the target number on every unpainted, non-transparent guide cell.
   • Hide numbers below a tested zoom threshold and expose a Zoom in to see numbers hint.
   • Painted cells hide their number regardless of whether the artist followed the suggested color.
   • Erasing a cell reveals its number again.

3. Numbered palette

   • Display stable 1..N badges on guide swatches.
   • Selecting a swatch may highlight its remaining unpainted target cells, but all readable numbers remain available.
   • Keep palette controls semantic and keyboard reachable.

4. Editable guidance

   • All valid drawing colors paint normally, including off-guide choices.
   • Optional feedback may distinguish matching and reinterpreted cells, but must not shake, block, or punish.
   • Feedback must not rely on color alone and continuous strokes must not spam live-region announcements.

5. Progress information

   • Track covered guide cells, not exact-color correctness.
   • Remaining counts are based on unpainted guide cells.
   • Progress is informational; it never decides when the work is complete.

Acceptance

• The board remains fully drawable with mouse, pen, and touch navigation.
• Off-guide colors stick and remain normally undoable.
• Every unpainted cell shows a number at readable zoom; no illegible numbers render below the threshold.
• A 48×48 normal-preset guide remains responsive.
• Current color, remaining count, progress, and restricted-action explanations have DOM-accessible representations.