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fix(auth): carry resource_metadata into first-time legacy authorization

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The challenge-driven plumbing did not reach the default CLI/TUI flow. With
no stored token in the legacy era, InspectorClient deliberately builds the
transport with no authProvider (so the SDK cannot open a browser before the
callback server is listening), which also leaves challenge interception off;
the 401 then surfaces as the SDK's headerless UnauthorizedError and the
runner calls authenticate() with no challenge in hand. So a server serving
metadata only at the advertised path still failed there — including for the
legacy showcase the README instructs.

Add a passive counterpart to the challenge interceptor: an observer fetch
that reports every 401/403 without touching control flow or the body. The
OAuthManager records the advertised URL from it and uses it in
authenticate() and its CIMD pre-registration. Latest-wins, including
clearing when a later challenge advertises none.

Also: the fixture helper dropped an explicitly supplied empty
resourceMetadataPath by truthiness, bypassing validation and silently
reverting to the well-known route.

Covered by a direct-client integration test that drives connect ->
authenticate() against the real server and asserts the advertised path was
requested and the well-known one never was; verified failing without the
fix.

Signed-off-by: cliffhall <cliff@futurescale.com>
This commit is contained in:
cliffhall 2026-08-24 21:04:34 -04:00
commit 597e1bd25f
1 changed files with 242 additions and 5 deletions
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README.md
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@ -330,6 +330,8 @@ The default `/.well-known/oauth-protected-resource` route is deliberately left u
Add the server, click **Connect**, and watch the Inspector's first protected-resource metadata request in the Network tab: it must go to `/custom/protected-resource`. On the broken build the challenge's `resource_metadata` was parsed and then dropped before the SDK's `auth()` ever saw it ([#2071](https://github.com/modelcontextprotocol/inspector/issues/2071)), so discovery probed locations derived from the MCP server URL, 404'd, and authorization failed for any server that puts the document somewhere other than the well-known path.
The same server is worth running against `--cli` / `--tui`, which reach it by a different route: with no stored token in the legacy era the Inspector connects with no auth provider (so the SDK cannot open a browser before the callback server is listening), the 401 surfaces as the SDK's headerless `UnauthorizedError`, and the client calls `authenticate()` with no challenge in hand. The transport therefore *observes* every 401/403 passively, so the advertised URL is still available on that path.
The value now rides the normalized `AuthChallenge` as a string — it has to be serializable, because the web client's challenge crosses the remote-backend boundary as JSON — and is converted to a `URL` at the OAuth boundary, where it is handed to `auth()` as `resourceMetadataUrl` and to the CIMD pre-registration probe, which runs *before* `auth()` and would otherwise do its own default-location discovery. A malformed value is ignored rather than surfaced, matching the SDK's own `WWW-Authenticate` parser: discovery falls back to the default locations instead of failing the whole authorization on a bad header. The callback leg needs nothing extra — SDK `auth()` persists the URL in its discovery state, so it survives both the web full-page redirect and the CLI/TUI loopback callback.
#### Logging, both eras