Prove proposal authoring through the shipped guide and source-bound runtime

[noeltock]

Problem

The 0.9 authoring path described a proposal workflow, but did not yet prove that a small model could follow the shipped guide, produce a canonical plan, and carry that exact plan through a real WordPress editor and frontend. The remaining proposal failures were also too vague to correct efficiently. Closes #65. Closes #70. Closes #71. Closes #72.

Solution

The shipped guide now defines the complete proposal-first workflow and the package exposes a source-bound runtime proof. Equivalent image dimensions are normalised, invalid native relationships return actionable diagnostics, and the utility-style hero fixture exercises editable native content rather than screenshot or Custom HTML fallbacks.

The generated wrapper also preserves full-width source canvases and source-authored vertical spacing without changing saved block markup.

Behaviour	Read first	Proof
Complete proposal workflow	skills/block-runner/references/GUIDE.md	Packed guide example and canonical-plan validation
Equivalent image dimensions	src/author/index.ts	Focused proposal and author tests
Actionable proposal failures	src/author/proposal.ts	Parent, binding, and grid diagnostics tests
Source canvas fidelity	src/authoring/generate.ts	WordPress 7.1: 42/42 layout pairs, 1.00 agreement
Native editing and patterns	scripts/authoring-runtime-worker.cjs	Save/reopen and synced-pattern runtime checks

Diff

+1,774 −110 · 27 files · no migration or public API break

 source HTML + stylesheet
   → source-bound proposal
   → canonical authoring plan
   → generated native block package
   → WordPress editor, frontend, pattern, fidelity and accessibility receipt

Testing & verification

Reviewed revision: 0095101ed6bcbef3829a15555ab5297c3724b327

• npm test -- --run test/authoring.generate.test.ts test/authoring.runtime.test.ts: 20/20 passed.
• npm test -- --run test/coverage.test.ts: 45/45 passed.
• npm run typecheck and git diff --check: passed.
• Fresh gpt-5.6-luna low-effort run against frozen inputs: canonical plan on the first submission.
• The exact saved plan on WordPress 7.1: build, editor save/reopen, frontend, accessibility, native structure, synced pattern, source/style coverage and warnings all passed; fidelity was 42/42 pairs at 1.00 with no 1440px or 390px overflow.
• Exact-head CI is the final merge gate.

The ad-hoc one-fixture wrapper still reports missing declared theme metadata after the worker completes; that is suite metadata, not a failed runtime dimension.

Risk / rollout

Saved markup is unchanged. The generated template version moves to v11 so regenerated packages receive the canvas and flow-spacing fixes. A regression presents as a theme-constrained canvas or compressed vertical rhythm; rollback is the final two compiler commits.