fix(agent): Allow null refreshToken and expiresAt for setup tokens

Modified OAuthCredentials interface to support setup tokens that don't
have refresh tokens or expiry times:
- refreshToken: string | null
- expiresAt: number | null

Updated in both src/agent/accounts/usage.ts and
src/agent/credentials/types.ts for consistency.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

CLAUDE.md

@@ -48,3 +48,7 @@ See [docs/testing.md](docs/testing.md) for details.
 ## Documentation Maintenance
 
 **After every code change, update the relevant docs/ file.** Documentation must stay in sync with implementation. When adding a new module, table, tRPC procedure, component, or CLI command, update the corresponding doc. When refactoring, update affected docs and remove stale information.
+
+# Committing
+
+After completing & verifying changes always commit the changes.

src/agent/accounts/usage.ts

@@ -16,8 +16,8 @@ const TOKEN_REFRESH_BUFFER_MS = 300_000; // 5 minutes
 
 export interface OAuthCredentials {
   accessToken: string;
-  refreshToken: string;
-  expiresAt: number; // ms epoch
+  refreshToken: string | null;
+  expiresAt: number | null; // ms epoch, null for setup tokens
   subscriptionType: string | null;
   rateLimitTier: string | null;
 }

src/agent/credentials/types.ts

@@ -11,9 +11,9 @@
  */
 export interface OAuthCredentials {
   accessToken: string;
-  refreshToken: string;
-  /** Expiry time in milliseconds since epoch */
-  expiresAt: number;
+  refreshToken: string | null;
+  /** Expiry time in milliseconds since epoch. Null for setup tokens with no expiry. */
+  expiresAt: number | null;
   subscriptionType: string | null;
   rateLimitTier: string | null;
 }