diff --git a/src/commands/config/index.ts b/src/commands/config/index.ts
index 000f265..bc97e72 100644
--- a/src/commands/config/index.ts
+++ b/src/commands/config/index.ts
@@ -63,7 +63,7 @@ export function registerConfigCommands(program: Command): void {
     );
 }
 
-function getNestedValue(obj: Record<string, unknown>, path: string): unknown {
+function getNestedValue(obj: object, path: string): unknown {
   const keys = path.split(".");
   let current: unknown = obj;
   for (const key of keys) {
@@ -75,9 +75,9 @@ function getNestedValue(obj: Record<string, unknown>, path: string): unknown {
   return current;
 }
 
-function setNestedValue(obj: Record<string, unknown>, path: string, value: string): void {
+function setNestedValue(obj: object, path: string, value: string): void {
   const keys = path.split(".");
-  let current: Record<string, unknown> = obj;
+  let current: Record<string, unknown> = obj as Record<string, unknown>;
   for (let i = 0; i < keys.length - 1; i++) {
     const key = keys[i];
     if (typeof current[key] !== "object" || current[key] === null) {
diff --git a/src/types/index.ts b/src/types/index.ts
new file mode 100644
index 0000000..d714bc7
--- /dev/null
+++ b/src/types/index.ts
@@ -0,0 +1,30 @@
+export interface DeviceAuthResponse {
+  device_code: string;
+  user_code: string;
+  verification_uri: string;
+  verification_uri_complete?: string;
+  expires_in: number;
+  interval: number;
+}
+
+export interface TokenResponse {
+  access_token: string;
+  token_type?: string;
+  expires_in?: number;
+  refresh_token?: string;
+}
+
+export interface WaveConfig {
+  version: string;
+  currentProject: string;
+  projects: Record<string, {
+    organizationId: string;
+    organizationName: string;
+    baseUrl?: string;
+    region?: string;
+  }>;
+  defaults: { outputFormat: OutputFormat; protocol?: string; color: "auto" | "on" | "off" };
+  telemetry: { enabled: boolean; errorReporting: boolean };
+}
+
+export type OutputFormat = "table" | "json" | "yaml";