open-standards

2026-10-17

Transaction Science

jcp: a chained decision enforces caveats, and a chain cannot drop one

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`decide_chained` evaluated no caveat at all: not the leaf's, not any
ancestor's. It is the decision path behind jcp-wire's endpoint (§11),
jcp-channel, jouleclaw-jcp and joule-code-jcp. Those always present a
chain, even a one-link chain for an undelegated grant. So `PayloadIs`,
`NotBefore`, `NotAfter`, `CallerIs`, `ActionIn`, `MaxCostUj` and
`ModelIn` were enforced only on the single-grant `decide`/`authorize`
path, which the conformance suite exercises.

Separately, `verify_chain` checked capability, budget, expiry and depth
at each hop, but not that a child carries its parent's caveats or no
wider money ceiling. `attenuate` refuses both when it mints. A chain
minted by hand verified anyway and conveyed the authority the caveat
withheld.

- `verify_chain` refuses a hop that drops a parent caveat
  (`caveats_narrow`) or widens or drops its money ceiling
  (`funds_narrows`). Both are denied `attenuation-violation`.
- The chained decision's checks move into `check_chained`, which now
  evaluates every link's caveats. Cost-dependent ones are evaluated when
  the cost is known.
- `authorize_chained` / `charge_chained` add the two-phase metered path
  for a chain. Authorize debits nothing and reports the least any link
  has left. Charge debits every link, so siblings share their parent as
  in `decide_chained`, and a per-call breach is reported with the joules
  still debited.
- SPEC §4.2 states both rules and the chained metered path. C7's
  conformance check covers an inherited caveat and a dropped one.

Checked on the build host:
- jcp-rs: 501 tests pass, and the conformance suite passes all checks.
- Every vector gen-vectors writes is byte-identical.
- jouleclaw-jcp, joule-code-jcp and sandbox-jcp pass their tests.
- mesh, joule-ui, joulehook and jouledesk compile.
- Mutations each fail tests: chains ignoring caveats, `verify_chain`
  allowing a dropped caveat, and a charge debiting only the leaf.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

f0952309c1

2026-10-17 10:44:16 -04:00

jcp: a chained decision enforces caveats, and a chain cannot drop one #300

2026-10-17