When RFC 9728 protected-resource metadata names no authorization server, the
MCP server URL stands in as one. `getAuthorizationServerUrl` built that with
`new URL("/", serverUrl)`, which discards the path — exactly the part discovery
needs when the server is not hosted at the domain root. The SDK's
`buildDiscoveryUrls` derives the path-scoped well-known locations from that
pathname, so an origin-only value could only ever probe the domain root, which
404s for a server like `https://example.com/mod/minilesson/mcp.php`.
Keep the path (and strip query/fragment, which an RFC 8414 issuer never
carries). A straight swap would regress the case the origin-only value did
serve — a server that merely lives under a path while publishing its metadata
at the root — so the URL becomes the first of two candidates:
`getAuthorizationServerUrlCandidates` yields the path-scoped form then the bare
origin, and `discoverAuthorizationServerMetadataForServer` walks them, treating
a candidate's failure as non-fatal while another remains and rethrowing the
first error only when all of them fail.
`discoverScopes` and the CIMD pre-registration probe both go through the walk.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013hzwzS8UvBsr4yZm7o7sev
Signed-off-by: cliffhall <cliff@futurescale.com>
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