Provenance / verification: an additive layer for OKF bundles

Thanks for OKF - the format is clean, and the "producers MAY include any additional keys" rule makes it easy to build on.

One gap shows up the moment agents act on shared bundles: a consumer has no way to verify that a bundle came from who it claims and hasn't been altered. The metadata stops at timestamp - there's no signature or integrity check. (Karpathy's original LLM-wiki gist has comments raising the same worry: stale synthesis pages that still look authoritative.)

I put together a small, additive layer that stays inside the spec:

optional provenance frontmatter keys (source, source_url, licence, measured_at) - additional keys the spec already permits
a root okf.manifest.json (not a reserved filename) that lists a SHA-256 of every file plus a provenance envelope, Ed25519-signed over its canonical form
a standalone verifier that re-hashes the files and checks the signature against the issuer's published key
Drop the manifest and it's a plain OKF bundle again - no fork, no required SDK. Repo (Apache-2.0): https://github.com/dynamicfeed/signed-okf

Sharing in case it's useful to the ecosystem, or as a reference if OKF ever wants to address provenance natively. Happy to align naming and conventions with the spec. Either way, thanks for shipping this.

Review the OKF bundle rules and the linked signed-okf repository, focusing on the optional provenance frontmatter, root okf.manifest.json, and standalone verifier described here. A useful outcome would require a decided scope and conventions for whether provenance belongs in this project and how it should integrate with existing bundles.

Written by the indexing model from the issue text.