Instruction file imported from ernop/tesla-video-viewer (.cursor/rules/product-md.mdc). Copyright stays with the author.

product.md is the design record

product.md holds goals, intentions, product surface, runtime constraints, and decisions (including rejected approaches). A change is not finished until product.md matches it. This applies to every turn on this repo, not only when the user mentions the file.

When you add, change, or drop a feature, or learn something that would change a future design choice, write it into product.md in the same turn. Include the why. That includes playback, plates, location, UI, README screenshot policy, and tests that encode intended behavior. If a path was tested and rejected, record the result so it is not proposed again as if it were unknown.

Do not put local paths, secrets, or clip contents in product.md. Do not publish identifiable real plates in README.md or docs/. Runtime how-to stays in README.md. Design and intent stay in product.md. If README and product.md disagree, fix README to match product.md.