feat(mcp): cut over to the SDK envelope and declare the two missing conformance fields - #9681
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…onformance fields
The SDK envelope has served all production traffic since 2026-08-06 12:15 UTC,
with parity verified live across 12 protocol cases and 95/98 zero-argument
tools. The flag has done its job. Keeping it means keeping a second envelope
nobody exercises, which is how the untested path becomes the one that breaks,
so mcpSdkEnvelopeEnabled and its branch are removed.
The malformed-input branch stays, and is not a rollback. The SDK's transport
answers 400 -32700 Parse error for the whole request, which is wrong three
ways: -32700 is reserved for JSON that did not parse (-32600 is Invalid
Request), a JSON-RPC error belongs inside a 200, and for a mixed batch the SDK
drops the valid members outright. That last one is data loss, so malformed
input is answered by dispatchMessage directly and always will be.
Two MCP 2025-11-25 fields were never emitted:
Tool.execution.taskSupport declared "forbidden" on every tool -- this
server registers no task store, and absent the
declaration a client learns that by attempting a
task-augmented call and failing.
Implementation.websiteUrl both on serverInfo, both what a client renders in
Implementation.icons a server picker. Icons point at real published
assets on our own origin.
Icons are server-level only. The spec allows them per tool, but all 224 would
carry the identical set -- roughly 45 KB added to a tools/list every client
holds in context, for nothing the handshake did not already say. Same
reasoning that refused tools/list pagination in #9648, and asserted so the
decision is explicit rather than an omission someone later "fixes".
Adding websiteUrl turned up three copies of the site origin (src/feeds.ts,
src/subnet-news.ts, and the icons wanted a fourth); collapsed into SITE_ORIGIN
in src/contracts.ts beside PRIMARY_DOMAIN.
The parity harness becomes a contract test: with one implementation left there
is nothing to diff against, so every expectation is now the literal response a
caller receives. That is the stronger form regardless -- a comparison passes
happily when both sides regress together, which initialize was caught doing
during the migration.
Closes #9680
Closes #9647
Deploying with
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| Status | Name | Latest Commit | Updated (UTC) |
|---|---|---|---|
| ✅ Deployment successful! View logs |
metagraphed-registry-sync-api | 27b79d5 | Aug 06 2026, 12:39 PM |
Deploying with
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| Status | Name | Latest Commit | Updated (UTC) |
|---|---|---|---|
| ✅ Deployment successful! View logs |
metagraphed-data-api | 27b79d5 | Aug 06 2026, 12:38 PM |
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Superagent didn't find any vulnerabilities or security issues in this PR. |
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Summary
Three things on the MCP surface, all found while wiring #9677.
1. Cut over to the SDK envelope — no flag, no second path
The SDK envelope has served all production traffic since 2026-08-06 12:15 UTC, with parity verified live across 12 protocol cases and 95/98 zero-argument tools. The flag has done its job; keeping it means keeping a second envelope nobody exercises, which is how the untested path becomes the one that breaks.
mcpSdkEnvelopeEnabledand its branch are gone. Every well-formed request is served by the SDK.The malformed-input branch stays, permanently — it is not a rollback. The SDK's transport answers
400 -32700 Parse errorfor the whole request, which is wrong three ways:-32600Invalid Request-32700Parse error — reserved for JSON that didn't parse200— a JSON-RPC error is a successful HTTP exchange400, which also starts firing the #9639 refusal eventThe third is data loss, so malformed input is answered by
dispatchMessagedirectly and always will be.2.
Tool.execution.taskSupportwas never emittedMCP 2025-11-25 defines it as
optional/required/forbidden. This server registers no task store, so a task-augmented call cannot be honoured — and absent the declaration a client discovers that by attempting one and failing. Declared"forbidden"on every tool, emitted once atlistToolDefinitionsso the next tool added carries it without anyone remembering.3.
Implementation.websiteUrlandImplementation.iconswere never emittedBoth are
serverInfofields a client renders in a server picker. Now declared, pointing at real published assets (favicon.svg,android-chrome-192x192.png,android-chrome-512x512.png) on our own origin — verified reachable, and asserted same-origin so a third-party host can't creep in.Server-level only, deliberately. The spec allows
iconsper tool, but all 224 would carry the identical set — roughly 45 KB added to atools/listevery client holds in context, for nothing the handshake didn't already say. Same reasoning that refusedtools/listpagination in #9648. Asserted, so it reads as a decision rather than an omission someone later "fixes".Adding
websiteUrlturned up three copies of the site origin (src/feeds.ts,src/subnet-news.ts, and the icons wanted a fourth). Collapsed intoSITE_ORIGINinsrc/contracts.tsbesidePRIMARY_DOMAIN.The parity harness becomes a contract test
With one implementation left there is nothing to diff against, so
tests/mcp-sdk-parity.test.ts→tests/mcp-envelope-contract.test.ts, and every expectation is now the literal response a caller receives. That's the stronger form regardless: a comparison passes happily when both sides regress together — whichinitializewas caught doing during the migration.The malformed-input cases still exercise the non-SDK branch. That's not legacy coverage; the branch is permanent.
Verification
A pre-existing allowlist in
tests/mcp-server.test.tscaughtexecutionas an unpublished key on first run — working exactly as designed; added there with the reason.Closes #9680
Closes #9647