jcp-wire: the endpoint decides at its own clock, and a captured request is decided once #322

Merged
dcharlot merged 1 commit from fix/jcp-wire-endpoint-clock-and-replay into main 2026-10-18 19:02:35 -04:00
Owner

The defect

The jcp/1 endpoint (jcp-wire, SPEC §11) decided every request at the now the request carried, and debited it every time it arrived. The request is signed by its caller, the grant's subject, so the caller chose both:

  • Time: a caller could stamp a request before its grant expired, or inside a NotAfter it had since left, and be decided as of that moment.
  • Replay: a captured request presented again was decided again and debited again. SPEC §11 described this as intended ("replays into the same deterministic decision and the same budget accounting").

The fix

  • The endpoint's clock decides. Endpoint decides at its own clock: with_clock, the system clock by default. A request's now is a freshness stamp. One more than the window (with_skew, default 300 s) from the clock is denied stale-request and sealed like any other denial.
  • A request is decided once. Within the window the endpoint remembers each request it decided, by content id. One presented again is denied replayed, neither decided nor debited. Once a stamp leaves the window it is forgotten and a replay of it is stale, so memory stays bounded.
  • New deny reasons: DenyReason::StaleRequest and DenyReason::Replayed, with their labels.
  • SPEC §11 now says three things:
    • the endpoint's clock decides;
    • a request is decided once;
    • the cost is the holder's measurement. The endpoint debits the declared cost as given, so the requester must be the party that metered the action: the grant's holder at the enforcement point, as a Mesh steward is. It must never be the governed agent reporting its own consumption.
  • C8 covers a replay, a stale request, and a grant that expires between a request's stamp and the endpoint's clock.

jcp-wire's only users are the conformance suite and jcp-threshold's test. Both now pin the endpoint's clock to the stamps their requests carry.

Checked

On the build host:

  • jcp-rs: 517 tests pass, three of them new in jcp-wire. The conformance suite passes all checks, including C8 and C13.
  • Vectors: every vector is byte-identical.
  • Downstream: every workspace depending on jcp-schema builds (mesh, jouleclaw, joule-code, sandbox, joule-ui, joulehook, jouledesk).
  • Clippy is clean.
  • Mutations: each fails tests, and each also fails C8:
    • deciding at the caller's now
    • deciding a replay again
    • no freshness window
  • Flake, unrelated: jcp-gateway's process-tree energy tests flaked twice under host load during full runs. Alone they pass every time, and this change doesn't touch that crate.

🤖 Generated with Claude Code

## The defect The `jcp/1` endpoint (`jcp-wire`, SPEC §11) decided every request at the `now` the request carried, and debited it every time it arrived. The request is signed by its caller, the grant's subject, so **the caller chose both**: - **Time:** a caller could stamp a request before its grant expired, or inside a `NotAfter` it had since left, and be decided as of that moment. - **Replay:** a captured request presented again was decided again and debited again. SPEC §11 described this as intended ("replays into the same deterministic decision and the same budget accounting"). ## The fix - **The endpoint's clock decides.** `Endpoint` decides at its own clock: `with_clock`, the system clock by default. A request's `now` is a freshness stamp. One more than the window (`with_skew`, default 300 s) from the clock is denied `stale-request` and sealed like any other denial. - **A request is decided once.** Within the window the endpoint remembers each request it decided, by content id. One presented again is denied `replayed`, neither decided nor debited. Once a stamp leaves the window it is forgotten and a replay of it is stale, so memory stays bounded. - **New deny reasons:** `DenyReason::StaleRequest` and `DenyReason::Replayed`, with their labels. - **SPEC §11** now says three things: - the endpoint's clock decides; - a request is decided once; - **the cost is the holder's measurement.** The endpoint debits the declared cost as given, so the requester must be the party that metered the action: the grant's holder at the enforcement point, as a Mesh steward is. It must never be the governed agent reporting its own consumption. - **C8** covers a replay, a stale request, and a grant that expires between a request's stamp and the endpoint's clock. jcp-wire's only users are the conformance suite and jcp-threshold's test. Both now pin the endpoint's clock to the stamps their requests carry. ## Checked On the build host: - **jcp-rs:** 517 tests pass, three of them new in jcp-wire. The conformance suite passes all checks, including C8 and C13. - **Vectors:** every vector is byte-identical. - **Downstream:** every workspace depending on jcp-schema builds (mesh, jouleclaw, joule-code, sandbox, joule-ui, joulehook, jouledesk). - **Clippy** is clean. - **Mutations:** each fails tests, and each also fails C8: - deciding at the caller's `now` - deciding a replay again - no freshness window - **Flake, unrelated:** jcp-gateway's process-tree energy tests flaked twice under host load during full runs. Alone they pass every time, and this change doesn't touch that crate. 🤖 Generated with [Claude Code](https://claude.com/claude-code)
jcp-wire: the endpoint decides at its own clock, and a captured request is decided once
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6cf9023940
The `jcp/1` endpoint decided every request at the `now` the request
carried, and debited it every time it arrived. The request is signed by
its caller, the grant's subject, so the caller chose both:
- **Time.** A caller could stamp a request before its grant expired, or
  inside a `NotAfter` it had since left, and be decided as of that
  moment.
- **Replay.** A captured request presented again was decided again and
  debited again. SPEC §11 described that as intended ("replays into the
  same deterministic decision and the same budget accounting").

The fix:
- **Clock.** `Endpoint` decides at its own clock (`with_clock`; the
  system clock by default). A request's `now` is a freshness stamp: one
  more than the window (`with_skew`, default 300 s) from the clock is
  denied `stale-request` and sealed like any other denial.
- **Replay.** Within the window the endpoint remembers each request it
  decided, by content id. One presented again is denied `replayed`,
  neither decided nor debited. Once a stamp leaves the window it is
  forgotten, and a replay of it is stale, so memory stays bounded.
- **Deny reasons.** `DenyReason::StaleRequest` and `DenyReason::Replayed`
  are new, with their labels.
- **Spec.** SPEC §11 says the endpoint's clock decides, a request is
  decided once, and the cost is the holder's measurement. The endpoint
  debits the declared cost as given, so the requester must be the party
  that metered the action, the grant's holder at the enforcement point
  (as a Mesh steward is), never the governed agent reporting its own
  consumption.
- **Conformance.** C8 covers a replay, a stale request, and a grant that
  expires between a request's stamp and the endpoint's clock.

jcp-wire's only users are the conformance suite and jcp-threshold's test.
Both now pin the endpoint's clock to the stamps their requests carry.

Checked on the build host:
- jcp-rs: 517 tests pass, three of them new in jcp-wire. The conformance
  suite passes all checks, including C8 and C13.
- Every vector is byte-identical, and clippy is clean.
- Every workspace depending on jcp-schema builds: mesh, jouleclaw,
  joule-code, sandbox, joule-ui, joulehook, jouledesk.
- Mutations each fail tests: deciding at the caller's `now` (also fails
  C8), deciding a replay again (also fails C8), and no freshness window
  (also fails C8).
- jcp-gateway's process-tree energy tests flaked twice under host load
  during full runs; alone they pass every time, and this change does not
  touch that crate.

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