diff --git a/clients/cli/src/cli.ts b/clients/cli/src/cli.ts
index ddd92d10..b5d8e42d 100644
--- a/clients/cli/src/cli.ts
+++ b/clients/cli/src/cli.ts
@@ -71,8 +71,8 @@ async function callMethod(
   serverSettings: InspectorServerSettings | undefined,
   args: MethodArgs & { method: string },
   clientConfig: ClientConfig,
-  cliAuthOverrides?: RunnerClientConfigOverrides,
-  callbackUrlConfig?: RunnerOAuthCallbackConfig,
+  cliAuthOverrides: RunnerClientConfigOverrides,
+  callbackUrlConfig: RunnerOAuthCallbackConfig,
 ): Promise<void> {
   const __dirname = dirname(fileURLToPath(import.meta.url));
   const packageJsonPath = join(__dirname, "../package.json");
@@ -93,9 +93,8 @@ async function callMethod(
   };
   const redirectUrlProvider = new MutableRedirectUrlProvider();
   if (isOAuthCapableServerConfig(serverConfig)) {
-    redirectUrlProvider.redirectUrl = formatRunnerOAuthRedirectUrl(
-      callbackUrlConfig!,
-    );
+    redirectUrlProvider.redirectUrl =
+      formatRunnerOAuthRedirectUrl(callbackUrlConfig);
     environment.oauth = {
       storage: new NodeOAuthStorage(),
       navigation: new ConsoleNavigation(),
@@ -258,14 +257,14 @@ async function callMethod(
       inspectorClient,
       serverConfig,
       redirectUrlProvider,
-      callbackUrlConfig!,
+      callbackUrlConfig,
       serverSettings,
     );
 
     const result = await withCliAuthRecoveryRetry(
       inspectorClient,
       redirectUrlProvider,
-      callbackUrlConfig!,
+      callbackUrlConfig,
       serverSettings,
       runMethod,
     );
diff --git a/core/mcp/oauthManager.ts b/core/mcp/oauthManager.ts
index 63c8ca14..878495fa 100644
--- a/core/mcp/oauthManager.ts
+++ b/core/mcp/oauthManager.ts
@@ -10,6 +10,7 @@ import { EMPTY_OAUTH_FLOW_STATE } from "../auth/types.js";
 import type { OAuthTokens } from "@modelcontextprotocol/sdk/shared/auth.js";
 import type { OAuthClientInformation } from "@modelcontextprotocol/sdk/shared/auth.js";
 import { mcpAuth } from "../auth/mcpAuth.js";
+import type { OAuthStorage } from "../auth/storage.js";
 import { parseOAuthState } from "../auth/utils.js";
 import type { EnterpriseManagedAuthIdpConfig } from "../client/types.js";
 import type { ClientConfig } from "../client/types.js";
@@ -104,6 +105,19 @@ export class OAuthManager {
     return this.params.getServerUrl();
   }
 
+  /**
+   * Return the configured OAuth storage, throwing a clear error if it is
+   * absent. Used on the EMA re-mint/persist paths, which are only reached for
+   * a fully-configured OAuth-capable server (storage present).
+   */
+  private requireStorage(): OAuthStorage {
+    const storage = this.oauthConfig.storage;
+    if (!storage) {
+      throw new Error("OAuth storage is required for this operation.");
+    }
+    return storage;
+  }
+
   private async createOAuthProvider(): Promise<BaseOAuthClientProvider> {
     if (
       !this.oauthConfig.storage ||
@@ -284,7 +298,7 @@ export class OAuthManager {
           requestedScope,
         );
         if (scopeToPersist) {
-          await this.oauthConfig.storage!.saveScope(
+          await this.requireStorage().saveScope(
             this.getServerUrl(),
             scopeToPersist,
           );
@@ -422,7 +436,7 @@ export class OAuthManager {
       protocol: protocolFromOAuthConfig(this.oauthConfig),
       configuredScope: this.oauthConfig.scope,
       enterpriseManagedAuth: this.params.enterpriseManagedAuth,
-      storage: this.oauthConfig.storage!,
+      storage,
       flowState: this.oauthFlowState ?? undefined,
     });
   }
@@ -618,7 +632,7 @@ export class OAuthManager {
       const silent = await trySilentEmaAuth(config);
       if (silent.status === "success") {
         if (await this.checkAuthChallengeSatisfied(enriched)) {
-          const minted = await this.oauthConfig.storage!.getTokens(
+          const minted = await this.requireStorage().getTokens(
             this.getServerUrl(),
           );
           const scopeToPersist = resolvePersistedScopeAfterGrant(
@@ -626,7 +640,7 @@ export class OAuthManager {
             enriched.authorizationScopes?.join(" "),
           );
           if (scopeToPersist) {
-            await this.oauthConfig.storage!.saveScope(
+            await this.requireStorage().saveScope(
               this.getServerUrl(),
               scopeToPersist,
             );
diff --git a/test-servers/src/resolve-config.ts b/test-servers/src/resolve-config.ts
index 921e54e1..331bb549 100644
--- a/test-servers/src/resolve-config.ts
+++ b/test-servers/src/resolve-config.ts
@@ -29,7 +29,7 @@ function resolvePresetRefs<T extends { requiredScopes?: string[] }>(
   type: "tool" | "resource" | "resourceTemplate" | "prompt",
 ): T[] {
   if (!refs || refs.length === 0) return [];
-  const result: T[] = [];
+  const result: Array<{ requiredScopes?: string[] }> = [];
   for (const entry of refs) {
     const items = Array.isArray(entry) ? entry : [entry];
     for (const ref of items) {
@@ -42,11 +42,13 @@ function resolvePresetRefs<T extends { requiredScopes?: string[] }>(
       const resolved = resolvePreset(type, presetName, ref.params);
       const arr = Array.isArray(resolved) ? resolved : [resolved];
       for (const item of arr) {
-        result.push(mergeRequiredScopes(item as unknown as T, ref));
+        result.push(mergeRequiredScopes(item, ref));
       }
     }
   }
-  return result;
+  // The caller pairs `type` with the matching `T`, so each resolved preset is
+  // the requested definition kind; TS can't see that correspondence.
+  return result as T[];
 }
 
 /**