- in createCustomFetch function
- convert finalHeaders to headers object for node-fetch compatibility
- for SSE streams, convert node stream to response body to web ReadableStream since EventSource polyfill expects web-compatible stream
* In package-lock.json and package.json
- add node-fetch as a dependency
This fixes#600
- Add state for connectionType
- Fetch connectionType from localstorage if present
* In Sidebar.tsx
- Add dropdown for connectionType, only visible if transport type is not stdio
* In Sidebar.test.tsx
- set connectionType to "proxy"
* In useConnection.ts
- add connectionType param, defaulting to "proxy"
- add state for mcpSessionId
- Only check proxy health if the connection type is proxy
- create a serverUrl variable which will either be the proxy url OR the server url depending upon the connection type
- added captureResponseHeaders function to extract the protocol-related headers from a response.
- when creating transport options and connectionType is "direct" and transportType is not "stdio",
- add the appropriate `Accept` and `Content-Type` headers
- capture the protocol related response headers and store them in the custom fetch handler
- set serverUrl to be the server url, not the proxy url
- if connection type is proxy set serverUrl to the mcpProxyUrl
- use serverUrl instead of mcpProxyUrl for the transport instantiation
* In useConnection.test.tsx
- replaced test "sends X-MCP-Proxy-Auth header when proxy auth token is configured" with two tests:
- "sends X-MCP-Proxy-Auth header when proxy auth token is configured for 'proxy' connectionType"
- "does NOT send X-MCP-Proxy-Auth header when proxy auth token is configured for 'direct' connectionType"
- added Connection URL Verification section with 2 tests
- uses server URL directly when connectionType is 'direct'"
- "uses proxy server URL when connectionType is 'proxy'"
Register both normal and debug redirect URIs in client metadata to prevent mismatch errors when using the Auth tab's debug mode versus normal connection flow.
- Introduced CustomHeaders component for managing custom headers.
- Updated Sidebar to include CustomHeaders component.
- Enhanced useConnection hook to handle custom headers and legacy auth migration.
- Added tests for custom headers functionality.
- Updated package.json and package-lock.json for new dependencies.
* In `src/server/index.ts`,
- Added `updateHeadersInPlace` helper function to solve the stale header reference issue in `SSEClientTransport`. It mutates the header object in-place, ensuring the transport sees all updates, while carefully preserving the original `Accept` header required by the transport.
- in `/mcp GET`, `/mcp POST`, and `/message POST`, use `updateHeadersInPlace` to replace current headers with new headers, retaining the Accept header.
Adds a mechanism to dynamically inject and update HTTP headers for ongoing proxy sessions, resolving an issue where headers introduced after the initial handshake (e.g, Mcp-Protocol-Version) were not being forwarded to the server.
The core problem was that the `transportToServer` instance was created once with a static set of headers. This meant that critical, dynamically added headers like `mcp-protocol-version` and `last-event-id` were being dropped in subsequent requests.
The solution implemented here is to wrap the `fetch` function used by the HTTP-based transports (`StreamableHttp` and `SSE`). This custom wrapper merges the latest headers from the client with the headers of each outgoing request from the proxy, ensuring all headers are preserved for the lifetime of the session.
Changes:
In `src/index.ts`:
- Added `sessionHeaderHolders`, a `Map` to store the most recent set of headers for each active session ID.
- Added `createCustomFetch`, a new helper function that creates a `fetch` wrapper. This wrapper merges the session headers from `sessionHeaderHolders` with the request-specific headers from the SDK (like `Content-Type`)
- In `createTransport`, use `createCustomFetch` for both the `StreamableHTTPClientTransport` and `SSEClientTransport`. This injects the dynamic header logic into the transport layer.
- In `/mcp`, `/sse`, `/message` route handlers, added logic to update the `sessionHeaderHolders` map with the latest headers from every incoming client request.
- Added cleanup logic to the `onsessionclosed` callback and the `/mcp` DELETE handler to remove session data from `sessionHeaderHolders`.
- In `getHttpHeaders`, more robust handling of `string[]` and `undefined` values from `req.headers`, satisfying the `"strict": true` TypeScript configuration.
