Follow-up audit completed. I made the image tool configurable for both regional API hosts, synchronized the three lesson docs, diagram, and generated web data, and added a focused request-contract test. I ran python -m pytest tests -q (25 passed, 32 subtests), tsc --noEmit, and npm run build.

Follow-up audit completed. I aligned the image tool schema with the documented prompt limit and aspect-ratio default, updated the touched lesson and generated content, and pushed commit 4156fe6. I ran python -m pytest tests -q (26 passed, 32 subtests), npx tsc --noEmit, and npm run build.

Follow-up audit completed. I removed generated web artifacts from the PR diff because prebuild regenerates them from synchronized lesson sources; the final net diff now contains only source and test files with no CJK added lines. I pushed commit 81d211f and reran python -m pytest tests -q (26 passed, 32 subtests), npx tsc --noEmit, and npm run build.