Evidence-bundle integrity¶

OpenMed can verify a local, counts-only evidence bundle before review with openmed.risk.check_evidence_bundle. Verification is deterministic and does not make network calls. It reads evidence bytes only to calculate SHA-256 digests; the returned report contains counts and stable failure categories, never file paths, manifest values, or evidence contents.

Bundle contract¶

A bundle is a directory containing manifest.json and the files referenced by its files entries. Paths must be relative POSIX paths inside the bundle, and each entry names a section and a canonical sha256:<64 lowercase hex> digest. The default required sections are summary, metrics, and provenance. Manifests are limited to 1 MiB, 128 required sections, and 4,096 file entries. Manifest, file-entry, policy, and provenance mappings use closed key sets so free-text or identifying metadata cannot pass unnoticed. Manifests may also include manifest_hash, a canonical SHA-256 digest over the manifest with that field omitted.

{
  "schema_version": "openmed.evidence_bundle.v1",
  "policy_fingerprint": "sha256:1111111111111111111111111111111111111111111111111111111111111111",
  "required_sections": ["summary", "metrics", "provenance"],
  "provenance": {
    "source_fingerprint": "sha256:2222222222222222222222222222222222222222222222222222222222222222",
    "generator": "openmed-evaluator",
    "created_at": "2026-08-08T12:00:00Z"
  },
  "files": [
    {
      "path": "evidence/metrics.json",
      "section": "metrics",
      "sha256": "sha256:<digest>"
    }
  ]
}

The policy fingerprint is a caller-verifiable binding. Pass the expected fingerprint when the review context has one:

from openmed.risk import check_evidence_bundle

result = check_evidence_bundle(
    "./evidence-bundle",
    expected_policy_fingerprint="sha256:<policy-digest>",
)
if not result.passed:
    print(result.to_dict())

Provenance is complete only when it contains a source fingerprint, generator identifier, and timezone-qualified creation timestamp. A provenance entry may also repeat policy_fingerprint; if present, it must match the manifest's fingerprint.

Failure categories¶

Reports contain only these stable category names and aggregate counts:

Category	Meaning
`manifest_unreadable`	The manifest or bundle root could not be read locally.
`invalid_manifest`	The manifest shape, digest, or path contract is invalid.
`schema_mismatch`	The manifest schema is not supported by this verifier.
`policy_mismatch`	The policy fingerprint is missing, malformed, or unexpected.
`missing_section`	A required section has no manifest entry.
`incomplete_provenance`	Required safe provenance metadata is absent or malformed.
`missing_file`	A manifest-referenced evidence file is absent.
`hash_mismatch`	A file or optional manifest hash differs from its content.
`unsafe_path`	A file reference escapes the bundle or uses a symlink.
`unreadable_file`	A referenced path is not a readable regular file.

The checker is an integrity gate, not a compliance certification or clinical decision guarantee. Evidence must remain aggregate and synthetic in committed fixtures; raw identifiers and clinical text do not belong in manifests, reports, logs, or documentation.