Real deployments gate IdP selection, prompt behavior, or audience on a query
parameter the OAuth/OIDC core specs never standardized (Keycloak's
`kc_idp_hint`, OIDC's `login_hint` / `prompt` / `acr_values`, Auth0's
`audience`), and none of them could be driven from the Inspector.
The Inspector never builds the authorize URL — the SDK's `auth()` does, and it
exposes no hook for extra parameters — so the merge happens at the one seam
that sees the finished URL: `BaseOAuthClientProvider.redirectToAuthorization`.
It lives in `core/`, so web, CLI, and TUI all inherit it.
- `core/auth/authorizationParams.ts`: the reserved-key list (`client_id`,
`code_challenge`, `code_challenge_method`, `redirect_uri`, `resource`,
`response_type`, `scope`, `state`), the key validator the form renders
inline, and the merge itself. Reserved keys are dropped with a warning
rather than silently overriding PKCE / the state binding / RFC 8707;
blank-key rows are skipped; the caller's URL is never mutated.
- Applied to the authorization request only — nothing wires it into the token
request.
- Persisted as `oauth.authorizationParams` (a string record) on the per-server
config beside `scopes`, edited as key/value rows in Server Settings ->
Authorization ("Additional authorization parameters"), with an inline error
per offending row plus a section-level warning.
- The enterprise-managed (EMA) leg redirects to a *different* authorization
server (the enterprise IdP), so it goes through the explicit
`redirectToExternalAuthorization` entry point, which skips the merge — a
`kc_idp_hint` or `audience` meant for the MCP server's AS must never be
appended to the IdP's authorize URL.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RDXCSrnSBV7vZfxycG5Z6E
Signed-off-by: cliffhall <cliff@futurescale.com>
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