What a Bridge report is
Some engines outside Lispex already run their own pipelines and gates, and the
first Bridge profile covers source-to-target conversion evidence. The Vouch
Bridge gives such an engine a public evidence shape. After its own run, the
engine emits a Bridge report (vouch.bridge-report/v0) that binds
- the exact source bytes and target bytes, by hash and byte length
- the engine identity and commit
- the way of running that the engine declares, together with its capability ids
- the declared gate results, each
pass,fail, ornot-run - the hashes of linked proof or gate artifacts
- an explicit attests and excludes boundary saying what the report does and does not claim
The engine does not have to disclose its private implementation to emit one.
Check a report
Run the external engine separately, preserve its source and target bytes, then check the report and the artifacts it names.
lispex verify-bridge \
--source source.lspx \
--target translated.output \
bridge-report.jsonA successful check prints a Bridge verification report
(vouch.bridge-verify-report/v0). It says that the declared files and hashes
are internally consistent. It does not rerun the external engine.
You can also bind linked proof artifacts with
--linked <artifact-id>=<artifact-file>, and confirm that the report is
attached to the expected profile, subject, and route with
--expect-context <manifest.json>. These are checks on the receiving side.
They answer whether the report is bound to the bytes and subject you intended
to inspect, not whether the subject is correct.
A separate artifact class
A Bridge report is not a native differential receipt, and the two never
convert into each other. The tags, required fields, and verifier entrypoints
are disjoint. Native receipts (csk.differential-receipt/v0) go to
lispex verify, while Bridge reports go to lispex verify-bridge. Changing
a tag or adding native-looking fields does not promote external evidence
into native transcript agreement.
What the checker does not do
The checker validates report shape, bytes in their one accepted form, byte bindings, declared gates, and proof-link hashes. It does not run the external engine, inspect private implementation details, judge whether the target code is correct, or establish semantic equivalence between source and target.
A common mistake
A passing Bridge check means the evidence is well-formed and bound to the bytes you supplied. It is not a statement that the conversion is correct.
Keep going
Keep the Vouch overview nearby. It separates authentication, request binding, current execution agreement, and a local grant.