What a Bridge report is
Some engines outside Lispex already run their own pipelines and gates; 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 declared route and capability ids;
- the declared gate results, each
pass,fail, ornot-run; - the hashes of linked proof or gate artifacts; and
- an explicit attests/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 consumer-side checks: 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, canonical bytes, 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 prove 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.