verify_anchor_onchain / verifyAnchorOnchain / VerifyAnchorOnchain check an
anchor epoch against the chain itself in all three SDKs: one raw JSON-RPC
eth_call to the anchoring contract's getCommitment(batchId) comparing the
on-chain merkle root with the anchor's merkle_root, plus one
eth_getTransactionReceipt confirming status == 0x1 in the expected block.
The customer chooses the RPC endpoint — nothing asks Attesto to confirm
Attesto, and no web3/ethers dependency is added anywhere.
The getCommitment(string) selector (keccak256 first 4 bytes = a7b09e2a) is
pinned as a constant with the dynamic-string ABI encoding done manually;
a worked calldata example (computed once against web3 keccak) is asserted in
all three test suites, and APSProvenance.abi.json is copied into each SDK's
testdata with a test that flags the pinned selector for review if the ABI's
getCommitment signature ever changes. The contract address is read from the
anchor epoch's hashed payload (payload.contract_address).
Mocked-RPC tests cover match / root-mismatch / failed-tx / wrong-block /
missing-fields in each language with identical problem strings; a live test
against the production contract runs only when ATTESTO_LIVE_RPC_URL is set.
Go CLI gains `attesto anchors verify <id> --rpc-url <url>` (API fetch +
on-chain check in one step; existing get/remote-verify behavior unchanged).
READMEs updated per SDK.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
