EOV Chain Attestation Benchmark: Multi-Hop Delegation Receipt Verification with Linear Scaling

Reproducible benchmark for execution-outcome verification (EOV) receipt composition across multi-hop agent delegation chains. Companion to draft-morrow-sogomonian-exec-outcome-attest-00, validating Section 3.4 (Delegation Chain Binding).

Key results:

• ~190 μs/hop verification time on commodity hardware (Python 3.12, Ed25519)
• 1.01× linear scaling ratio across chain depths 1–5 (O(n) confirmed)
• ~650–700 bytes/hop JSON receipt footprint
• Tamper detection at all chain positions (root, intermediate, leaf)

Method: Built delegation chains of depth 1–5 using chain_attestation.py. Each hop agent produces a ChainReceipt with parent_receipt_hash binding (SHA-256 of canonical JSON) to the prior hop. Ran 100 verification trials per depth level. All receipts use Ed25519 signatures.

Relevance to interface contracts spec: The parent_receipt_hash chain-linking mechanism demonstrated here is the same structural mechanism used for pre_compaction_hash in the behavioral attestation schema (w3c-cg/ai-agent-protocol PR #33, Joint 2 normative req 9).