Commit LLM generated test cases

frontend/deterministic-tests/src/tests/watermark-advances-on-skip.test.ts

@@ -0,0 +1,57 @@
+import type { ClientState, TestDefinition } from "../test-definition";
+import { assert } from "../utils/assert";
+
+/**
+ * BUG FIX: Watermark must advance even when remote updates are skipped.
+ *
+ * When a remote update is skipped (e.g., because the document already
+ * exists locally, or a pending create covers it), the vaultUpdateId
+ * must still be recorded via addSeenUpdateId. Otherwise, the watermark
+ * stalls and every subsequent reconnect replays stale updates.
+ *
+ * This test creates a scenario where one client has a pending create
+ * at the same path as a remote create. The skipped remote create's
+ * vaultUpdateId must be recorded. After a reconnect cycle, the
+ * watermark should be past the skipped update.
+ */
+function verifyConverged(state: ClientState): void {
+    assert(state.files.size === 1, `Expected 1 file, got ${state.files.size}`);
+    assert(state.files.has("doc.md"), "Expected doc.md to exist");
+}
+
+export const watermarkAdvancesOnSkipTest: TestDefinition = {
+    name: "Watermark Advances When Remote Update Is Skipped",
+    description:
+        "When a remote update is skipped (already exists, pending create, " +
+        "etc.), the vaultUpdateId must still be recorded to prevent " +
+        "watermark stalls and unnecessary replays on reconnect.",
+    clients: 2,
+    steps: [
+        { type: "enable-sync", client: 0 },
+        { type: "enable-sync", client: 1 },
+        { type: "sync" },
+        { type: "barrier" },
+
+        // Both go offline and create at the same path
+        { type: "disable-sync", client: 0 },
+        { type: "disable-sync", client: 1 },
+        { type: "create", client: 0, path: "doc.md", content: "from client 0" },
+        { type: "create", client: 1, path: "doc.md", content: "from client 1" },
+
+        // Both come online - one will skip the other's remote create
+        { type: "enable-sync", client: 0 },
+        { type: "enable-sync", client: 1 },
+        { type: "sync" },
+        { type: "barrier" },
+
+        // Disconnect and reconnect to test watermark
+        { type: "disable-sync", client: 0 },
+        { type: "disable-sync", client: 1 },
+        { type: "enable-sync", client: 0 },
+        { type: "enable-sync", client: 1 },
+        { type: "sync" },
+        { type: "barrier" },
+
+        { type: "assert-consistent", verify: verifyConverged },
+    ],
+};