stacklok / toolhive / 30280044065

Build # 30280044065

Build Type

push

github

Committed by web-flow

Commit Message

Strip reserved io.modelcontextprotocol/* keys from responses (#6024)

* Generalize reserved _meta strip to the namespace

StripReservedModernMeta removed four named io.modelcontextprotocol/*
keys, which was enough for its only job at the time: keeping a
downstream Modern caller's per-request protocol metadata off a Legacy
backend hop. The response-path counterpart needs the same guard against
keys this list does not name -- serverInfo, subscriptionId, and whatever
a future revision adds -- so match the reserved namespace instead of
enumerating it, and drop the "Modern" from the name now that it guards
both revisions in both directions.

Matching a namespace over-reaches in one direction the old list could
not: the reserved prefix holds two kinds of key. Per-hop control keys
are a gateway's to terminate, but end-to-end semantic keys are merely
carried, and stripping those breaks the feature that depends on them.
passthroughMetaKeys exempts the two the 2025-11-25 task facility defines
-- related-task is a MUST on task-related responses, the direction the
response-path change filters. vMCP does not route tasks/* today, so
these are inert; the point is that this strip is what would silently
break them later.

Delete ReservedModernMetaKeys. It has no production consumers once the
predicate is a prefix, and its three test readers get stronger looping
on the namespace: they now catch any reserved key, not four named ones.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

* Own the reserved _meta namespace on responses

On the response path both revisions forwarded every backend _meta key
untouched. Modern overwrote io.modelcontextprotocol/serverInfo and let
the rest through; Legacy filtered nothing. A backend could therefore set
protocolVersion, clientInfo, or any other reserved key on a tools/call
result and have it reach the client as if vMCP had set it. vMCP, not the
backend, is the client's MCP peer, so no backend may speak for it -- and
of the res... (continued)

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