mcpx: Phase 2 of #2434 — advertised-capability gate at dispatch (-32601 for completion/complete pre-2025-03-26 and resources/subscribe when not advertised)

Phase 2 of design #2434 (mcpx error honesty, finished). Design doc: files/designs/code-mcpx-error-honesty.md in the keep-the-four-repos-healthy goal workspace. Independent of Phase 1. The decision is recorded on #2434; this phase implements its second slice.

Scope

Dispatch consults the same capability map advertisement used. One gate in internal/mcpserver dispatch, evaluated after the existing Removed() check (server.go:785, whose precedence it keeps): compute the capability map exactly as capabilities() (server.go:2410) does for this peer/version/connection, and refuse with -32601 ("no method X: capability Y not advertised") any method whose gating capability is absent or false in that map. Modern HTTP already pairs -32601 with 404 (modernStatus, internal/mcpserver/transport.go).

The gated set is ONLY the two proven disagreements — do not widen it in this phase:

completion/complete ← completions: today answered for every revision ("completion/complete is answered for every revision; only the capability that declares it is newer than 2024-11-05", capabilities() comment) — refuse only for revisions that cannot advertise completions (2024-11-05); revisions that can advertise it always do, so no served behaviour changes there.
resources/subscribe / resources/unsubscribe ← resources.subscribe: today dispatched unconditionally (server.go:938) even when advertisement said subscribe: false (no push channel). Refuse when the advertisement the peer actually saw said false.

Exempt by construction: negotiation methods (initialize, server/discover, ping where defined). Tasks keep their own -32021/-32601 logic. Accept-liberally stands for everything not in the gated set.

Triage must check first: when is push evaluated for the advertisement vs at dispatch — the gate must use the same evaluation the peer's advertisement used; if those can differ, that discrepancy is itself a bug to fix inside this phase before gating on it.

Acceptance

A 2024-11-05 peer calling completion/complete gets -32601; 2025-03-26+ peers are served exactly as today
resources/subscribe on a connection whose advertisement said subscribe: false gets -32601; with push available it works as today
The gate reads the same capabilities() computation as advertisement (single source — no second hand-maintained table of what is advertised)
Removed-method refusals keep precedence and their existing tests pass unchanged
Tests run via CI per fleet policy (no builds on the sandbox)

Out of scope: growing the gated set (needs its own evidence, per #2434), Phase 1's carriage, Phase 3's -32021.

Acceptance criteria

Dispatch refuses with -32601 (modern HTTP pairing 404 preserved) exactly the two proven disagreements named in the scope — completion/complete for revisions that cannot advertise completions, plus the second listed there — and nothing wider.
The gate consults the same capability map capabilities() computes for this peer/version/connection, evaluated after the existing Removed() check, whose precedence is kept.
Tests pin both refusals and that methods whose capability IS advertised still dispatch normally.

CODE-1243

🤖 agent-note:v1 — design-architect pass 16 (2026-10-29). Phase 2 of design #2434, independent of Phase 1. Triage packet enqueued: pilot task 3647 (queue=repo-health-code-pilot, status=queued, verified). Triage first checks the push-evaluation timing question named in the issue body, confirms scope against current main per #2434, and enqueues the implementation follow-up with the acceptance criteria intact.

Intake review (fleet monitor, 2026-10-29 run):

Related: design design(mcpx): error honesty, finished — peer errors relayed as peer errors, unadvertised methods refused, -32021 when a capability is truly required #2434; sibling phases mcpx: Phase 1 of #2434 — structured upstream-error carriage through the gateway + local-error origin marker #2435, mcpx: Phase 3 of #2434 — -32021 when no broker audience can answer + error-register truth-up (ERR-08, conflict #8, three gap rows) #2438. Independent of Phase 1, so this is the natural first slice to land.
Still live: yes — filed 2026-10-29; nothing merged since (main frozen, ci: merge queue ejects every PR — no merge since #2233 (10:57Z), entries dropped 2-6 min into AWAITING_CHECKS #2403).
Notes/risks: the scope is deliberately narrow (two proven disagreements); widening the gated set in this phase is the main scope risk. The capability map must be computed exactly as capabilities() does, or advertisement and enforcement drift apart again.
Suggested approach: one gate in dispatch after the Removed() check, reusing the capabilities() computation; pin both refusals with tests before touching anything else.

🤖 Agent note · picked up (resume)

Agent: queue worker (repo-worker-code), openchamber scheduled lane
Session / ID: queue task 3980
Found via: queue claim — resumed from checkpoint, did not restart
Task: implement the mcpx: Phase 2 of #2434 — advertised-capability gate at dispatch (-32601 for completion/complete pre-2025-03-26 and resources/subscribe when not advertised) #2436 advertised-capability gate at dispatch — PR feat(mcpx): advertised-capability gate at dispatch (#2436) #2873
Expectation: PR feat(mcpx): advertised-capability gate at dispatch (#2436) #2873 @bca478b93 open; build/lint/plugin green, stress FAILING on PR-own tests. Prior shift could not reach the laptop; this lane runs on the laptop, so resuming in the existing worktree and diagnosing the stress failure fresh.

fix(mcpx): gate only peers that declared a revision; configure notifi…

🤖 Agent note · parked (CI pending)

Agent: queue worker (repo-worker-code), openchamber scheduled lane
Session / ID: queue task 3980
State: PR feat(mcpx): advertised-capability gate at dispatch (#2436) #2873 @37212e724 pushed. Fix in this lane: gate skips peers that declared no revision (version-less callers served as today; genuine 2024-11-05 declarers still gated) + admit test configures s.Notify per Codex P2 (replied on the thread). Local verification: full mcpserver package green, gate+wp11 tests green under -race, gofmt clean.
CI: lint/plugin/docs green on the new head; stress (race/shuffle/repeat) still pending at the 5-minute poll limit. Codex re-review requested on the new head.
Resume: read PR feat(mcpx): advertised-capability gate at dispatch (#2436) #2873 checks fresh; if stress green and Codex round clean, merge (mergeable, no held labels) and complete; if Codex posts findings, disposition them first.

feat(mcpx): advertised-capability gate at dispatch (#2436) (#2873)

🤖 Agent note · done

Agent: queue worker (repo-worker-code), lane C shift
Session / ID: queue task 3980
Found via: queue claim — resumed from checkpoint
State: PR feat(mcpx): advertised-capability gate at dispatch (#2436) #2873 @37212e724 verified fresh: CI all green (build/lint/plugin/stress/docs), mergeState CLEAN, latest Codex round on 37212e7 clean (no findings); the one earlier Codex P2 (admit test notifier) was fixed in 37212e7, replied on its thread, and the thread is now resolved.
Outcome: PR feat(mcpx): advertised-capability gate at dispatch (#2436) #2873 squash-merged as 1e19bd6; this issue auto-closed. Capability gate at dispatch (mcpx: Phase 2 of #2434 — advertised-capability gate at dispatch (-32601 for completion/complete pre-2025-03-26 and resources/subscribe when not advertised) #2436, Phase 2 of design(mcpx): error honesty, finished — peer errors relayed as peer errors, unadvertised methods refused, -32021 when a capability is truly required #2434) is landed.

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mcpx: Phase 2 of #2434 — advertised-capability gate at dispatch (-32601 for completion/complete pre-2025-03-26 and resources/subscribe when not advertised) #2436

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mcpx: Phase 2 of #2434 — advertised-capability gate at dispatch (-32601 for completion/complete pre-2025-03-26 and resources/subscribe when not advertised) #2436

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developing-today commented on Oct 29, 2026

dezren39 commented on Oct 29, 2026

dezren39 commented on Oct 30, 2026

49 remaining items

dezren39 commented on Oct 31, 2026

dezren39 commented on Oct 31, 2026

dezren39 commented on Oct 31, 2026

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