File Verification Handoff Kit

Compare selected browser-local files with a strict integrity manifest and create an exact verification handoff packet without uploading file bytes.

Release engineers and operators handing off bounded file-integrity evidence while keeping selected files local.

Verification handoff

Hosted sample: unverified metadata comparison only

{
  "ok": true,
  "schema_version": "utilito.product-kit.v1",
  "kit": {
    "id": "file-verification-handoff-kit",
    "version": "1.0.0"
  },
  "result": {
    "status": "submitted_metadata_comparison_plan",
    "manifest_id": "release-2026-07",
    "file_bytes_received": false,
    "digests_recomputed": false,
    "submitted_digests_verified": false,
    "submitted_claim_policy_outcome": "claimed_pass_unverified",
    "policy": {
      "missing": "fail",
      "extra": "fail",
      "collision": "fail"
    },
    "report_format": "markdown",
    "rows": [
      {
        "name": "hello.txt",
        "expected_bytes": 5,
        "algorithm": "SHA-256",
        "submitted_by_caller": true,
        "computed_locally": false,
        "verified": false,
        "status": "claimed_match_unverified"
      }
    ],
    "limitations": [
      "Hosted direct, API, and MCP compare caller-submitted metadata only; submitted digests are unverified claims.",
      "Digest equality is an integrity comparison, not authenticity or provenance.",
      "No signature verification or release certification is performed.",
      "No malware scanning is performed; inspect files with appropriate security tools."
    ]
  },
  "receipt": {
    "input_bytes": 415,
    "output_bytes": 1505,
    "complete_bytes": 1505,
    "expected_rows": 1,
    "submitted_digest_rows": 1,
    "declared_bytes": 5,
    "operations": 1,
    "omitted_items": 0,
    "warnings": []
  },
  "provenance": {
    "deterministic": true,
    "model_used": false,
    "network_used": false,
    "storage_used": false,
    "file_bytes_received": false,
    "digests_recomputed": false,
    "core_versions": {
      "file_verification_handoff_kit": "1.0.0",
      "file_hash_checksum_verifier": "existing-core",
      "file_integrity_manifest": "utilito.file-integrity.v1",
      "evidence_report": "1.0.0"
    }
  },
  "error": null
}

Limits and meaning

Files are read only after count and declared-size preflight. Names are normalized to NFC and collisions, paths, controls, bidi controls, and unsafe basenames fail closed.

Digest equality is an integrity comparison only. It is not authenticity, provenance, signature verification, malware scanning, or release certification.

Hosted direct, API, and MCP accept strict manifest metadata and caller-submitted digest rows only. They never receive files, recompute hashes, or call submitted claims verified.