test: cover corrupted client state

tests/state-and-rules.test.ts

@@ -1,4 +1,4 @@
-import { mkdtemp, readFile, rm } from "node:fs/promises";
+import { mkdtemp, readFile, rm, writeFile } from "node:fs/promises";
 import { tmpdir } from "node:os";
 import { join } from "node:path";
 
@@ -13,6 +13,7 @@ import {
   hasClientSecret,
   loadYonexusClientState,
   saveYonexusClientState,
+  YonexusClientStateCorruptionError,
   type YonexusClientState
 } from "../plugin/core/state.js";
 import { signMessage, verifySignature } from "../plugin/crypto/keypair.js";
@@ -81,6 +82,23 @@ describe("Yonexus.Client state store", () => {
     expect(second.state.privateKey).toBe(first.state.privateKey);
     expect(second.state.publicKey).toBe(first.state.publicKey);
   });
+
+  it("SR-06: raises a corruption error for malformed client state files", async () => {
+    const filePath = await createTempStatePath();
+    await saveYonexusClientState(filePath, {
+      ...createInitialClientState("client-a"),
+      updatedAt: 1_710_000_000
+    });
+
+    await writeFile(filePath, '{"version":1,"identifier":"client-a","updatedAt":"bad"}\n', "utf8");
+
+    await expect(loadYonexusClientState(filePath, "client-a")).rejects.toBeInstanceOf(
+      YonexusClientStateCorruptionError
+    );
+    await expect(loadYonexusClientState(filePath, "client-a")).rejects.toThrow(
+      "invalid updatedAt"
+    );
+  });
 });
 
 describe("Yonexus.Client rule registry", () => {