Support RFC 8414 path-based issuer discovery URLs#4406
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PR #4348 (f64d807) replaced the /.well-known/ catch-all mux pattern with explicit exact registrations to prevent the auth server from intercepting /.well-known/oauth-protected-resource. This broke RFC 8414 Section 3.1 discovery for path-based issuers: clients construct /.well-known/oauth-authorization-server/{issuer-path} but the exact pattern only matched /.well-known/oauth-authorization-server. Register trailing-slash prefix variants on both the http.ServeMux (Routes()) and chi router (WellKnownRoutes) so subpaths are routed to the discovery handlers. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## main #4406 +/- ##
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Coverage 69.49% 69.50%
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Files 485 485
Lines 49841 49845 +4
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+ Hits 34638 34645 +7
+ Misses 12528 12525 -3
Partials 2675 2675 ☔ View full report in Codecov by Sentry. 🚀 New features to boost your workflow:
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tgrunnagle
approved these changes
Mar 27, 2026
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Summary
/.well-known/catch-all mux pattern with explicitexact registrations to prevent the auth server from intercepting
/.well-known/oauth-protected-resource(owned by the vMCP server). Thisinadvertently broke RFC 8414 Section 3.1 discovery for path-based issuers:
clients construct
/.well-known/oauth-authorization-server/{issuer-path}but the exact pattern only matched
/.well-known/oauth-authorization-server.http.ServeMux(
Routes()) and chi router (WellKnownRoutes) so subpaths are routed tothe discovery handlers.
Type of change
Test plan
task test)Verified end-to-end with a VirtualMCPServer deployed to a kind cluster
behind ngrok with a path-based issuer (
https://toolhive.ngrok.app/inject-test).Claude Code successfully discovered the auth server via
/.well-known/oauth-authorization-server/inject-test, completed themulti-upstream OAuth flow (Okta + GitHub + Google), and called tools.
Changes
pkg/authserver/runner/embeddedauthserver.goRoutes()for discovery pathspkg/authserver/server/handlers/handler.gopkg/authserver/runner/embeddedauthserver_test.goTestRoutesexpected count (4 → 6)Special notes for reviewers
The regression was introduced in #4348 which correctly avoided a
/.well-known/catch-all but did not account for RFC 8414 Section 3.1 where clients insert
/.well-known/oauth-authorization-serverbefore the issuer's path component.This only manifests when the issuer has a path (e.g., multi-tenant deployments
behind a shared domain). Issuers at the domain root are unaffected.
Generated with Claude Code