Previous attempt set `strictJsonSchema:false` on createOpenAI()
(factory ignores unknown keys), so wire was still strict:true and
sparse edits {brightness:0.3} were rejected: Missing 'arrangement'.
- src/llm/llmTweak.js: use provider.chat(modelId) (/chat/completions,
correct for Meta via gateway, not /responses) and pass
`providerOptions:{ openai:{ strictJsonSchema:false } }` on
generateObject where the SDK actually reads it.
- src/llm/spec.js: edits fields nullable instead of optional — strict
requires every key in `required` when `additionalProperties:false`;
nullable makes required = all 7 (model emits null for unchanged),
clampEdits already strips nulls so NO_EDITS still works. Prompt now
instructs "use null for unchanged, example { bpm:null,... }".
- test/llm.test.js: minimal valid result now all-null with one edit.
Co-Authored-By: Claude <noreply@anthropic.com>
