fix(transport): validate JSON-RPC request ID is a safe integer#1809
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Aboudjem wants to merge 3 commits intomodelcontextprotocol:mainfrom
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fix(transport): validate JSON-RPC request ID is a safe integer#1809Aboudjem wants to merge 3 commits intomodelcontextprotocol:mainfrom
Aboudjem wants to merge 3 commits intomodelcontextprotocol:mainfrom
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When a JSON-RPC request arrives with a numeric ID exceeding Number.MAX_SAFE_INTEGER, Zod schema validation correctly rejects it (z.number().int() enforces safe integer range in Zod v4). However, the rejected message falls through to the "Unknown message type" error handler, which silently drops it without sending any response back to the client. This causes the server to appear permanently hung. This fix detects request-like messages that fail schema validation in the onmessage handler and responds with a JSON-RPC -32600 (Invalid Request) error instead of silently ignoring them. Closes modelcontextprotocol#1765 Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
tsgo flags `mock.calls[0][0]` as "Object is possibly undefined" — add `!` after the first index access to match the convention used everywhere else in this test file. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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Summary
Fixes #1765 - Server hangs indefinitely when JSON-RPC request ID exceeds
Number.MAX_SAFE_INTEGER.Root cause: When a request arrives with a numeric ID like
9007199254740992(MAX_SAFE_INTEGER + 1), Zod v4'sz.number().int()correctly rejects it (.int()enforces the safe integer range). However, the rejected message falls through to theelsebranch in theonmessagehandler, which calls_onerrorwith "Unknown message type" and silently drops the message without ever sending a response. The client waits forever for a response that never comes.Fix: In the
onmessagehandler withinProtocol.connect(), detect request-like messages that fail schema validation (havejsonrpc,id, andmethodfields but didn't passisJSONRPCRequest) and respond with a JSON-RPC-32600(Invalid Request) error instead of silently dropping them.Changes
packages/core/src/shared/protocol.ts- Added validation in theonmessagehandler to detect and respond to malformed request messagespackages/core/test/shared/protocol.test.ts- Added 3 tests: unsafe integer ID returns error, MAX_SAFE_INTEGER works normally, string IDs work normallyTest plan