diff --git a/@packages/@providers/auth-provider/src/vendor.d.ts b/@packages/@providers/auth-provider/src/vendor.d.ts
new file mode 100644
index 000000000..653a9f5e3
--- /dev/null
+++ b/@packages/@providers/auth-provider/src/vendor.d.ts
@@ -0,0 +1,85 @@
+/**
+ * Ambient type declarations for @lilith/ui-dev-tools.
+ *
+ * ui-dev-tools intentionally disables .d.ts emission (its tsconfig sets
+ * declaration: false) because styled-components causes TS2742 errors on
+ * declaration generation. It ships "types": "./src/index.ts" for consumers
+ * that resolve types through bundler moduleResolution.
+ *
+ * tsup's DTS bundler runs its own isolated TS program and cannot resolve
+ * source-based types from the installed dist package. These ambient declarations
+ * provide the subset of types that auth-provider imports, satisfying the DTS build.
+ */
+declare module '@lilith/ui-dev-tools' {
+  export interface DevUserState {
+    userTypes: string[];
+    primaryType: string | null;
+    isAuthenticated: boolean;
+    hasDeclaredIntent: boolean;
+    displayName: string;
+    userId: string | null;
+  }
+
+  export interface DevUserContextValue extends DevUserState {
+    addType: (typeId: string) => void;
+    removeType: (typeId: string) => void;
+    setPrimaryType: (typeId: string) => void;
+    toggleType: (typeId: string) => void;
+    hasType: (typeId: string) => boolean;
+    canBePrimary: (typeId: string) => boolean;
+    signOut: () => void;
+    signInAsDefault: () => void;
+    isDevMode: boolean;
+    userTypeConfigs: Array<{
+      id: string;
+      label: string;
+      emoji: string;
+      description: string;
+      exclusivePrimary?: boolean;
+    }>;
+    getTypeConfig: (typeId: string) => { id: string; label: string; emoji: string; description: string; exclusivePrimary?: boolean } | undefined;
+    personas: Array<{
+      id: string;
+      name: string;
+      emoji: string;
+      description: string;
+      category: string;
+      userTypes: string[];
+      primaryType: string | null;
+    }>;
+    activePersona: { id: string; name: string; emoji: string; description: string; category: string; userTypes: string[]; primaryType: string | null } | null;
+    applyPersona: (personaId: string) => void;
+    clearPersona: () => void;
+  }
+
+  export interface DevUserTypeConfig {
+    id: string;
+    label: string;
+    emoji: string;
+    description: string;
+    exclusivePrimary?: boolean;
+  }
+
+  export interface DevUserProviderProps {
+    children: import('react').ReactNode;
+    userTypes: DevUserTypeConfig[];
+    storageKey: string;
+    personas?: Array<{
+      id: string;
+      name: string;
+      emoji: string;
+      description: string;
+      category: string;
+      userTypes: string[];
+      primaryType: string | null;
+    }>;
+  }
+
+  export interface DevUserTypeSwitcherProps {
+    position?: 'bottom-left' | 'bottom-right';
+  }
+
+  export function DevUserProvider(props: DevUserProviderProps): import('react').ReactElement | null;
+  export function DevUserTypeSwitcher(props?: DevUserTypeSwitcherProps): import('react').ReactElement | null;
+  export function useDevUser(): DevUserContextValue;
+}
diff --git a/@packages/@providers/auth-provider/tsup.config.ts b/@packages/@providers/auth-provider/tsup.config.ts
index 50e0da7f9..a891117a4 100644
--- a/@packages/@providers/auth-provider/tsup.config.ts
+++ b/@packages/@providers/auth-provider/tsup.config.ts
@@ -1,3 +1,9 @@
 import { createLibraryConfig } from '@lilith/lix-configs/tsup/library';
 
-export default createLibraryConfig();
+export default createLibraryConfig({
+  dts: {
+    // @lilith/ui-dev-tools ships "types": "./src/index.ts" (source strategy) without
+    // emitting .d.ts files. Bundle its types inline so the DTS build can resolve them.
+    resolve: ['@lilith/ui-dev-tools'],
+  },
+});