This is a preliminary implementation of OAuth 2.1 for the client.
When a StreamableClientTransport encounters a 401 Unauthorized response
from the server, it initiates the OAuth flow described in thec
authorization section of the MCP spec
(https://modelcontextprotocol.io/specification/2025-06-18/basic/authorization).
On success, the transport obtains an access token which it passes
to all subsequent requests.
Much remains to be done here:
* Resource Indicators, as described in section 2.5.1 of the MCP spec.
* All of this is unexported, so it is available only to our own
StreamingClientTransport. We should add API so people can use it
with their own transports.
* And, of course, tests. We should test against fake implementations
but also, if we can find any, real reference implementations.
For #19
Co-authored-by: Jonathan Amsterdam <jba@google.com>
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Co-authored-by: Jonathan Amsterdam <jba@google.com>