jcp-x402: demonstrate the settlement coupling in the runnable example #25
2026-07-18
jcp-x402: demonstrate the settlement coupling in the runnable example
The example showed ingest, dual-ceiling minting, the money-cap denial, and the currency refusal — but not `seal_settlement`, which is the crate's most distinctive contribution. It was tested and undemonstrated. Adds the settlement step: the host settles on chain, the meter reports what the paid compute actually consumed (5812 µJ measured, against a 6000 µJ estimate — so the receipt binds what happened, not what was budgeted), and the two are sealed together. Then it runs the verification a third party would run: recompute the coupling id from the settlement record and compare it to the receipt's payload_hash. It also shows the negative, which is the property that makes the binding worth anything: re-pointing at a different transaction yields a different id, so the receipt cannot be moved to another settlement. Output reads `coupling verified: true` / `re-point to another tx → id matches: false`. Example-only; no library change. Co-Authored-By: Claude Opus 4.8 <[email protected]>