Snapshots

A run reads exactly two states of the repository: a base and a candidate. Each is named by a full commit ID, or the candidate can be the staged index. Nothing else counts as input. There is no working-directory mode, no branch-name resolution, and no fetching. If a needed object is not in the local object store, the run refuses; see Limits and refusals.

Amiss reads Git’s storage itself instead of asking the git command. Loose objects, packfiles, deltas, and the index file are parsed by the engine, and the parsers reject instead of repairing. A tree with entries out of order, an index whose checksum does not match, a delta chain deeper than the published limit: each one is a typed refusal, never a best-effort read. Every SHA-1 object is re-hashed as it is read, with collision detection switched on, so an object that does not hash to its own name simply does not exist as far as the evaluation is concerned.

File access happens through directory handles opened step by step, never following links. A symlink, junction, or reparse point at the repository root, at .git, at objects, or anywhere along the path to an object is refused outright. The refusal is a different error from the object being absent, and that difference is deliberate: someone who can plant a link must not be able to make the scanner read files outside the repository, and must equally not be able to disguise the attempt as a missing object.

What a refusal looks like in the report’s errors array, here for a base commit the store does not hold:

{
  "code": "GIT_OBJECT_MISSING",
  "phase": "git"
}

The row also carries path, path_bytes_hex, resource, configured_limit, and observed_lower_bound fields, null wherever they do not apply, so every refusal has the same shape and a consumer never parses two formats. When the refused thing is a name the path grammar rejects, path_bytes_hex holds its exact bytes as lowercase hex, so the report never swallows what it refused.

Neither snapshot is trusted more than the other. A base commit missing from a shallow clone is a refusal, not an empty tree, because treating an absent base as empty would make every document look newly added and flood the report with false introduced findings. Comparing two trees only means something when both trees are exactly the ones you asked for.