fix(controller): recover MCP auth session from RequestExtra in tool handlers#1853
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fix(controller): recover MCP auth session from RequestExtra in tool handlers#1853onematchfox wants to merge 1 commit into
RequestExtra in tool handlers#1853onematchfox wants to merge 1 commit into
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RequestExtra in tool handlers
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Pull request overview
This PR addresses an auth-context propagation gap in the Go MCP Streamable HTTP handling path: tool handlers lose the original HTTP request context (and thus the auth.Session), so invoke_agent re-authenticates using the preserved request headers in CallToolRequest.Extra to ensure downstream A2A calls can forward the user’s JWT.
Changes:
- Recover
auth.SessioninsidehandleInvokeAgentby re-authenticating fromRequestExtra.Header, then attach it to the handler context. - Add unit tests validating Authorization propagation to the A2A backend when an MCP client supplies (or omits) an Authorization header.
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| File | Description |
|---|---|
| go/core/internal/mcp/mcp_handler.go | Re-authenticates from RequestExtra.Header to restore the session in tool-handler context for downstream A2A auth propagation. |
| go/core/internal/mcp/mcp_handler_test.go | Adds end-to-end-ish unit tests covering auth propagation behavior through MCP → A2A. |
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| // The Go MCP SDK detaches the HTTP request context when dispatching to | ||
| // tool handlers, so auth.AuthSessionFrom(ctx) returns nothing. Recover | ||
| // the auth session from the HTTP headers preserved in RequestExtra so | ||
| // that the A2A client's outbound request to the agent carries the user's JWT. | ||
| if extra := req.GetExtra(); extra != nil { | ||
| if session, err := h.authenticator.Authenticate(ctx, extra.Header, nil); err == nil { | ||
| ctx = auth.AuthSessionTo(ctx, session) | ||
| } | ||
| } |
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RequestExtra doesn't carry query params
… handlers The Go MCP SDK detaches the HTTP request context before dispatching to tool handlers. From the [SDK source](https://github.com/modelcontextprotocol/go-sdk/blob/v1.5.0/mcp/streamable.go#L485-L487): > // Pass req.Context() here, to allow middleware to add context values. > // The context is detached in the jsonrpc2 library when handling the > // long-running stream. This means the auth session placed by `AuthnMiddleware` is not visible via `auth.AuthSessionFrom(ctx)` in tool handlers. The SDK does preserve the original HTTP headers in [RequestExtra.Header](https://github.com/modelcontextprotocol/go-sdk/blob/v1.5.0/mcp/streamable.go#L1155-L1158) though. Re-authenticate from those headers at the top of handleInvokeAgent so the A2A client's outbound request to the agent carries the user's JWT. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com> Signed-off-by: Brian Fox <878612+onematchfox@users.noreply.github.com>
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The Go MCP SDK detaches the HTTP request context before dispatching to tool handlers. From the SDK source:
This means the auth session placed by
AuthnMiddlewareis not visible viaauth.AuthSessionFrom(ctx)in tool handlers.The SDK does preserve the original HTTP headers in RequestExtra.Header though.
Re-authenticate from those headers at the top of
handleInvokeAgentso the A2A client's outbound request to the agent carries the user's JWT.