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fix(auth): pass the challenge's resource_metadata URL to SDK auth()

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An RFC 9728 `WWW-Authenticate: Bearer resource_metadata="…"` challenge was
parsed and then dropped by the normalized `AuthChallenge`, so every
challenge-driven `mcpAuth()` call ran discovery without it and probed
locations derived from the MCP server URL instead. OAuth failed outright
against any server whose metadata document lives off the well-known path.

The SDK handles this correctly inside its own transports, but the Inspector
never reaches that path — it intercepts the 401 and drives `auth()` itself
to capture the authorization URL and run the step-up scope union.

Carry the advertised URL on `AuthChallenge` as a string (it crosses the web
client's remote-backend boundary as JSON), convert it at the OAuth boundary,
and pass it to the standard challenge leg, the forced step-up leg, and CIMD
pre-registration — which runs before `auth()` and did its own discovery. A
malformed value is ignored rather than surfaced, matching the SDK's parser.
The callback leg needs nothing: SDK `auth()` persists the URL in its
discovery state.

Adds an `oauth.resourceMetadataPath` test-server mode that moves the
document off the well-known path entirely, so the integration test proves
discovery genuinely fails without the fix.

Closes #2071

Signed-off-by: cliffhall <cliff@futurescale.com>
This commit is contained in:
cliffhall 2026-08-24 19:48:40 -04:00
commit f8a46726b7
1 changed files with 469 additions and 6 deletions
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11
test-servers/src/load-config.ts
View file

@ -19,6 +19,8 @@ export interface ConfigFileOAuth {
mode?: "combined" | "protected-resource";
authorizationServers?: string[];
resource?: string;
/** Serve RFC 9728 metadata from this path and advertise it on 401 (#2071). */
resourceMetadataPath?: string;
issuerUrl?: string;
accessTokenIssuers?: string[];
jwksUri?: string;
@ -200,6 +202,15 @@ function validateConfig(
}
}
}
const metadataPath = oauth.resourceMetadataPath;
if (
metadataPath !== undefined &&
(typeof metadataPath !== "string" || !metadataPath.startsWith("/"))
) {
throw new Error(
`Invalid config in ${filePath}: oauth.resourceMetadataPath must be an absolute path starting with "/"`,
);
}
if (transportType === "stdio" && oauth.enabled === true) {
throw new Error(
`Invalid config in ${filePath}: oauth requires streamable-http or sse transport`,