Keep author-layout image URLs editor-valid after WordPress materialization

[chubes4]

Problem

Fixture 37 materializes blocks-engine/author-layout with a nested image whose saved block markup retains the relative source website/assets/materialized-svg/inline-svg-453b87c087581ebd.svg. WordPress resolves the editor DOM value to an absolute theme URL, so wp.blocks.validateBlock reports an attribute mismatch and marks the block invalid.

Evidence

• SSI PR: Fix Fixture 37 form and visual materialization static-site-importer#760 at 00cfb164
• Blocks Engine: 74fec9e9
• Homeboy run: b280bf88-2257-4915-9d80-f4c52ff6a538
• Fixture: 37-art-gallery-exhibition
• Block: blocks-engine/author-layout
• Mismatch: relative src=website/assets/materialized-svg/inline-svg-453b87c087581ebd.svg vs absolute runtime theme URL

Reproduction:

node tools/run-fixture-matrix.mjs --static-site-importer /path/to/static-site-importer --blocks-engine /path/to/blocks-engine --local --target-fixture 37-art-gallery-exhibition --surface-coverage 6

Acceptance

• Author-layout nested image serialization remains valid after WordPress resolves materialized asset URLs.
• The generic fix applies to URL-bearing nested content without fixture-specific selectors or paths.
• Fixture 37 editor validation reports no author-layout attribute mismatch.

AI Assistance

OpenAI GPT-5.6 Sol via OpenCode ran the seven-surface matrix, analyzed the editor validation evidence, and drafted this report. Chris Huber reviewed the evidence and remains responsible for the issue.

[chubes4]

Downstream acceptance proof now passes after #763 merged.

• SSI PR: Fix Fixture 37 form and visual materialization static-site-importer#760 at 00cfb164
• Blocks Engine repair merge: d1c81ffd
• Homeboy matrix run: 098366d4-f29b-41be-a75b-4f840fbd57b0
• Fixture: 37-art-gallery-exhibition, seven surfaces
• Editor validation: 2646/2646 blocks valid
• blocks-engine/author-layout invalid findings: 0
• Editor validity status: clean, warning count 0

The remaining seven findings are visual parity mismatches and do not include URL serialization or editor validity failures.

AI assistance: OpenAI GPT-5.6 Sol via OpenCode and Homeboy implemented the repair, ran the downstream matrix, analyzed the editor artifacts, and drafted this update. Chris Huber reviewed the evidence and remains responsible for the conclusion.