D414 - The test corpus is a manifest-driven fetch tool

Status: assumed Date: 2026-08-31

The test corpus is fetched from a tracked manifest naming each source and how to obtain it - a tagged release with a pinned, verified checksum, or a path into a sibling checkout - into an untracked, per-source directory; the fetch logic lives in its own crate and the command line is a thin front end over it.

Why: Tracking only the manifest keeps guest bytes out of the repository while keeping exactly how to reproduce the corpus in version control. Pinning and verifying a checksum for a tagged release catches a silent change under a tag that is supposed to be fixed; a sibling checkout with no published release yet is re-hashed each time instead, since there is no fixed point to verify against.

Rejected:

• Tracking guest bytes directly: the provenance boundary this project keeps excludes committing guest material.
• Fetching from a branch rather than a tag: a branch can move under a pinned reference without anyone noticing.