diff --git a/packages/auth/src/feature.manifest.ts b/packages/auth/src/feature.manifest.ts
new file mode 100644
index 0000000..0a36f54
--- /dev/null
+++ b/packages/auth/src/feature.manifest.ts
@@ -0,0 +1,42 @@
+import { defineFeature } from "@repo/core-shared/conformance";
+
+/**
+ * The auth feature's conformance manifest. Drives binding-slot types in
+ * `di/bind-production.ts` and is read by ESLint, the boot assertion, and
+ * the CI drift gate (later milestones).
+ *
+ * Conventions:
+ * - `mutates: true` for any use case that creates, updates, or deletes state
+ * - `audits` lists every audit event the use case emits (must match calls
+ *   to `auditLog.record(...)` in the factory body — ESLint enforces this
+ *   in a later story)
+ * - `publishes` / `consumes` cover cross-feature events through `IEventBus`
+ */
+export const authManifest = defineFeature({
+  name: "auth",
+  requiredCores: [],
+  useCases: {
+    signIn: {
+      mutates: false,
+      audits: [],
+      publishes: [],
+      consumes: [],
+    },
+    signUp: {
+      mutates: true,
+      audits: [],
+      publishes: [],
+      consumes: [],
+    },
+    signOut: {
+      mutates: true,
+      audits: [],
+      publishes: [],
+      consumes: [],
+    },
+  },
+  realtimeChannels: [],
+  jobs: [],
+} as const);
+
+export type AuthManifest = typeof authManifest;