---
'@modelcontextprotocol/client': minor
'@modelcontextprotocol/core-internal': minor
---

Dynamic Client Registration hygiene for the 2026-07-28 authorization requirements (SEP-837, SEP-2207). New `resolveClientMetadata(provider)` reads `provider.clientMetadata` and applies the spec defaults — `application_type` derived from the redirect URIs (loopback or custom scheme → `'native'`, otherwise `'web'`), `grant_types: ['authorization_code', 'refresh_token']` when omitted — and `auth()` feeds the resolved document to DCR only (scope selection still reads the raw consumer-supplied `clientMetadata` so statically-registered/CIMD clients are not pushed into `offline_access` + `prompt=consent`); consumer-set values are never overwritten. DCR rejection now throws the new `RegistrationRejectedError` carrying the HTTP status, raw body, and submitted metadata — **breaking for direct `registerClient()` callers**: rejection no longer throws `OAuthError`, so update `instanceof` checks. `OAuthClientMetadata` gains a typed `application_type?: string` field (expected `'native'` / `'web'`; tolerant on parse). `OAuthErrorCode` adds `InvalidRedirectUri`. The token-exchange, refresh, and Cross-App Access (`requestJwtAuthorizationGrant` / `exchangeJwtAuthGrant`) paths now throw the new `InsecureTokenEndpointError` for a non-`https:` token endpoint (`localhost` / `127.0.0.1` / `::1` exempt), and `auth()` surfaces it on the refresh branch instead of silently re-authorizing.