fix(client): let OAuth-derived Authorization override caller-supplied header#2475
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sanjibani wants to merge 2 commits into
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fix(client): let OAuth-derived Authorization override caller-supplied header#2475sanjibani wants to merge 2 commits into
sanjibani wants to merge 2 commits into
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… header Closes modelcontextprotocol#2208. StreamableHTTPClientTransport and SSEClientTransport both build the outgoing request's headers as: return new Headers({ ...headers, // common: Authorization (OAuth), mcp-session-id, mcp-protocol-version ...extraHeaders // caller-supplied via requestInit.headers }); This meant a caller-supplied Authorization placeholder (e.g. an env-var API key passed through the MCP config) was placed AFTER the SDK-derived common headers, which silently overrode OAuth-computed tokens and broke the auth-refresh flow once the placeholder went stale. Several MCP servers (Atlassian Rovo and others) let both API tokens and OAuth share the same Authorization header and rely on it being valid. Swap the spread order to so SDK-computed common headers (including the freshest OAuth token) take precedence, matching the merge order used elsewhere in the SDK. Caller-supplied non-auth headers still pass through unchanged. Test: a regression test in streamableHttp.test.ts seeds a stale Authorization placeholder in requestInit.headers alongside a working authProvider and asserts the request goes out with the OAuth-derived token. 722 client tests pass; lint + format clean.
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@modelcontextprotocol/client
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…ntextprotocol#2475) Signed-off-by: sanjibani <18418553+sanjibani@users.noreply.github.com>
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Closes #2208.
StreamableHTTPClientTransport and SSEClientTransport both build the outgoing request's headers as:
This meant a caller-supplied Authorization placeholder (e.g. an env-var API key passed through the MCP config) was placed AFTER the SDK-derived common headers, which silently overrode OAuth-computed tokens and broke the auth-refresh flow once the placeholder went stale. Several MCP servers (Atlassian Rovo and others) let both API tokens and OAuth share the same Authorization header and rely on it being valid.
Swap the spread order to
...extraHeaders, ...headersso SDK-computed common headers (including the freshest OAuth token) take precedence, matching the merge order used elsewhere in the SDK. Caller-supplied non-auth headers still pass through unchanged.Test: a regression test in
streamableHttp.test.tsseeds a stale Authorization placeholder inrequestInit.headersalongside a workingauthProviderand asserts the request goes out with the OAuth-derived token. 722 client tests pass; eslint + prettier clean.