Public source release of the hardened bridge runtime and fork-receipt conformance fixture. Includes deterministic offline post-oracle evidence in which the generator observes no second fixture-oracle call; the verifier checks receipt/log consistency and a fork-bound caller assertion under a published conformance key. This is mechanism-level evidence, not production-provider or environment attestation. CI passes on Python 3.11, 3.12, and 3.13. No PyPI publication is performed by this release.