Pin cache_ttl before the edge rewrite

The CDN edge decides how long to keep each response. A rewrite is planned, and nobody wrote down the rules.

Your task

Pin what cache_ttl does today. Not what a cache should do. What this one does.

• fill REGRESSION_TESTS with cases: the arguments in, the value it returns today
• a test that expects the RIGHT answer instead of the CURRENT one fails the clean run
• at submit each test runs again against versions of the function with one line changed
• a change your tests do not notice is behavior you left unpinned

The suite runs your tests against the untouched code, then against mutations you have not seen.