D002 - One shared build stamp

Status: decided Date: 2026-08-29

Every binary stamps its build through oops-build: the commit from git (with -dirty for a modified tree, or from OOPS_COMMIT when CI supplies it), the version, and the executable's own modification time. Stamp::is_exact is the check for a reproducible build.

Why: per-project copies each covered half the job and none noticed its gap, because a stamp reading no commit looks like a local build rather than a defect.

Rejected:

• A commit read only from an environment variable: correct only when something sets it.
• A compile-time build timestamp: records when one crate compiled, not when the binary linked.