Commit LLM generated test cases

frontend/deterministic-tests/src/tests/migrate-key-preserves-existing.test.ts

@@ -0,0 +1,59 @@
+import type { ClientState, TestDefinition } from "../test-definition";
+import { assert } from "../utils/assert";
+
+/**
+ * BUG FIX: migrateKey must not overwrite existing state at the new key.
+ *
+ * Scenario:
+ * 1. Client 0 creates file A.md, then immediately updates it
+ * 2. Server is paused so the create stalls (idempotency key unresolved)
+ * 3. Client 1 is online and also creates at A.md (different content)
+ * 4. Server resumes — both creates merge
+ * 5. Client 0's update should not be lost during key migration
+ *
+ * The test verifies that after convergence, the file exists with
+ * content from both clients' edits.
+ */
+function verifyContent(state: ClientState): void {
+    assert(state.files.size === 1, `Expected 1 file, got ${state.files.size}`);
+    assert(state.files.has("A.md"), "Expected A.md to exist");
+    const content = state.files.get("A.md") ?? "";
+    // Client 0's update should be present
+    assert(
+        content.includes("updated by client 0"),
+        `Expected content to include "updated by client 0", got: "${content}"`
+    );
+}
+
+export const migrateKeyPreservesExistingTest: TestDefinition = {
+    name: "Key Migration Preserves Existing Queue State",
+    description:
+        "When migrateKey is called and the new key already has queued " +
+        "events, the existing events must not be silently dropped.",
+    clients: 2,
+    steps: [
+        { type: "enable-sync", client: 0 },
+        { type: "enable-sync", client: 1 },
+        { type: "sync" },
+        { type: "barrier" },
+
+        // Pause server so create stalls
+        { type: "pause-server" },
+
+        // Client 0 creates and immediately updates
+        { type: "create", client: 0, path: "A.md", content: "initial" },
+        {
+            type: "update",
+            client: 0,
+            path: "A.md",
+            content: "updated by client 0"
+        },
+
+        // Resume server
+        { type: "resume-server" },
+        { type: "sync" },
+        { type: "barrier" },
+
+        { type: "assert-consistent", verify: verifyContent }
+    ]
+};