fix: Pass RequestInit options to auth requests #1066
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Fixes an issue where custom headers (like user-agent) and other RequestInit options set when creating transports were not being passed through to authorization requests (.well-known/ discovery, token exchange, DCR, etc.). Changes: - Created createFetchWithInit() utility in shared/transport.ts to wrap fetch with base RequestInit options - Transports now wrap their fetch function before passing to auth module - All RequestInit options (headers, credentials, mode, etc.) are now preserved - Auth-specific headers properly override base headers when needed - Extracted normalizeHeaders() to shared/transport.ts for reuse 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <[email protected]>
Added comprehensive tests to verify that: - Custom headers (like user-agent) from RequestInit are passed to auth requests - Auth-specific headers override base headers when needed - All RequestInit options (credentials, mode, cache, etc.) are preserved All 553 tests pass. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <[email protected]>
Fix linting errors by removing unused destructured url variables.
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@pcarleton checking if we can review this. The underlying problem is that @dcramer is trying to ban clients that spam auth endpoint. because we dont pass user-agent to the http client for auth discovery, he ends up getting generic user-agents and cant ban a specific client. |
pcarleton
requested changes
Nov 7, 2025
src/client/streamableHttp.ts
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| let result: AuthResult; | ||
| try { | ||
| // Wrap fetch to automatically include base RequestInit options | ||
| const fetchFn = createFetchWithInit(this._fetch, this._requestInit); |
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is there a reason to do this each time vs. in the constructor?
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let me ask claude why it thought this is a good idea :p
Move the createFetchWithInit() call from _authThenStart() to the constructor to avoid recreating the wrapper function on every auth attempt. This is more efficient and follows better practices. The wrapped fetch function is now stored in _fetchWithInit and reused across all auth-related calls in _authThenStart(), finishAuth(), and send(). Addresses code review feedback from @pcarleton 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <[email protected]>
pcarleton
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Nov 7, 2025
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Summary
Fixes an issue where custom headers (like
user-agent) and otherRequestInitoptions set when creating transports were not being passed through to authorization requests.Problem
When clients set custom headers via
requestInit.headerswhen instantiating transports (StreamableHTTPClientTransport,SSEClientTransport), these headers were correctly used for normal MCP operations but were lost during authorization requests such as:.well-known/metadata discoverySolution
Created a
createFetchWithInit()utility function insrc/shared/transport.tsthat wraps the fetch function to automatically include baseRequestInitoptions. The transports now use this wrapper before passing fetch to auth functions.Key Changes
Added
createFetchWithInit()utility (src/shared/transport.ts)RequestInitoptionsRequestInitoptions (credentials, mode, cache, etc.)Updated transports (
src/client/streamableHttp.ts,src/client/sse.ts)createFetchWithInit()to create wrapped fetch for auth requestsExtracted
normalizeHeaders()utility (src/shared/transport.ts)Benefits
RequestInitoptions preserved, not just headersTesting
Added comprehensive tests in
src/client/auth.test.ts:RequestInitare passed to auth discovery requestsRequestInitoptions are preservedAll 553 tests pass ✅
Test plan
Run the test suite:
npm testAll tests should pass (pre-existing failures in some test suites are due to missing dependencies, not related to these changes).
🤖 Generated with Claude Code