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Evaluate SDK middleware for protocol/tracing #1024
Description
Context
TypeScript SDK PR #1406 adds message middleware support:
modelcontextprotocol/typescript-sdk#1406
This adds sendMiddleware and receiveMiddleware options to Protocol, allowing transformation of JSON-RPC messages before sending and after receiving.
Potential Uses in Inspector V2
| Use Case | How Middleware Helps |
|---|---|
| Protocol capture | receiveMiddleware could capture all messages for Protocol page without modifying client logic |
| Request tracing | sendMiddleware could inject trace IDs for parent-child correlation |
| Protocol extensions | Add custom capabilities to initialize (e.g., inspector metadata) |
| Plugin architecture | Plugins could register middleware to intercept/modify messages |
| Debugging | Inject timestamps, add debugging headers |
Action Items
- Monitor PR Tools/prompts/resources vanish on connect: capability gate races the connect event #1406 for merge
- When merged, evaluate integration into
McpContext.tsx - Consider for request trace model (linking tool calls to sampling requests)
- Evaluate for plugin hooks in client features PR
Related
- feat(client): add Mantine UI with MCP SDK integration #1022 (Mantine UI) - current McpContext uses direct SDK connection
- spec: Add client features UX patterns (sampling/elicitation) #1011 (client features UX spec) - request trace model spec
- Inspector V2 Data Spec #983 (data spec) - history/logging architecture
Activity
cliffhall commentedon Aug 1, 2026
Triage: Priority = Low
Scored 4/16 with the priority rubric added to
AGENTS.mdin #1891, as part of the backlog triage in #1872. Added to project board #28 with Status Incoming — meaning filed and scored but not yet approved for work. A maintainer decides whether it moves to Todo.Related issues. One connected issue:
receiveMiddlewareis floated as a fix forScores are a starting point, not a verdict — the rubric is meant to be overruled when it's plainly wrong, provided the reason is written down.
[-]Evaluate SDK middleware for history/tracing[/-][+]Evaluate SDK middleware for protocol/tracing[/+]