Chain client 1.0.0 — capped Base checks

Chain client 1.0.0 buys structured results from four existing Base tools: transaction status ($0.003 maximum), wallet snapshot ($0.005), gas estimate ($0.002) and token allowance ($0.002). Quote commands never read keys or pay. Every buy requires an explicit per-invocation cap and an existing local X402_PRIVATE_KEY.

Download both chain-client.mjs and chain-client.mjs.sha256 into one folder, keeping filenames unchanged. Verify before running using the POSIX or PowerShell instructions in docs/chain-checks.md at this tag. Requires Node 20.19+; no npm installation or TypeScript is needed to use the executable. Source and reproducible build instructions are in clients/chain/README.md at this tag.

The client pins the HTTPS origin, full requested resource, fixed recipient, Base native USDC and exact scheme. It authorizes/submits at most once per invocation. Stop and reconcile after an uncertain signed outcome; there is no automatic retry or paid polling. It never sends the transaction being checked or changes a token approval. Caps are per invocation, not session/monthly allowances.

Transaction success is not proof of the intended token payment. Missing token rows are not proof of zero balance. Gas excludes Ethereum posting cost. Positive allowance need not cover the intended amount. Server receipts are not independent chain proof.

This separate client release does not change the Worker, API prices, handlers, existing reader downloads or Claude's checkout. Reader 1.7.6 remains the repository's latest release. Signing tests use offline fixtures; live quotes are unpaid operator checks. Funded delivery and customer demand remain unverified.

SHA-256 checksums detect mismatched files; they are not independent security signatures.