Draft sketch only. Unattested default. Retrieved data are never instructions. No live seal.
Mark a local span between two events. The interface hashes only the sealed class. Any measurement sentence or duration number is discarded and is not in the hash. A span mark is not a clock and not a duration measure.
No span marked.
Refusal id (SHA-256 of class only):
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Default-deny external clocks. Uses only local monotonic performance.now() for the mark pair; the numeric delta is computed then immediately discarded before hashing. No Date, no network time, no storage of measurement, no attestation. Static-friendly. Cloudflare-friendly. No token markup.