diff --git a/src/adapters/cursor/discovery.ts b/src/adapters/cursor/discovery.ts
index 15f529fdb0..61b4ed340c 100644
--- a/src/adapters/cursor/discovery.ts
+++ b/src/adapters/cursor/discovery.ts
@@ -231,15 +231,18 @@ export function isCursorRouterModelId(modelId: string): boolean {
 export function filterCursorConfiguredModelsByLiveDiscovery<T extends { id: string }>(
   configured: readonly T[],
   liveIds: readonly string[],
+  maxModeLiveIds: readonly string[] = [],
 ): T[] {
-  return configured.filter(model =>
-    !CURSOR_KNOWN_UNCALLABLE_MODEL_IDS.has(model.id)
-    && (
-      isCursorRouterModelId(model.id)
-      // Synthetic ultra rows ride their base model's account availability.
-      || isCursorModelAvailableForAccount(cursorUltraBaseModelId(model.id) ?? model.id, liveIds)
-    ),
-  );
+  return configured.filter(model => {
+    if (CURSOR_KNOWN_UNCALLABLE_MODEL_IDS.has(model.id)) return false;
+    if (isCursorRouterModelId(model.id)) return true;
+    const ultraBase = cursorUltraBaseModelId(model.id);
+    return isCursorModelAvailableForAccount(ultraBase ?? model.id, liveIds)
+      // Successful discovery is authoritative: synthetic ultra rows additionally require the
+      // account-specific Max Mode capability. Discovery failures bypass this filter and retain
+      // the static seed under the caller's existing degraded-catalog policy.
+      && (ultraBase === undefined || isCursorModelAvailableForAccount(ultraBase, maxModeLiveIds));
+  });
 }
 
 /**
diff --git a/src/codex/catalog/provider-fetch.ts b/src/codex/catalog/provider-fetch.ts
index 1c8d62ae76..9a0c1717d7 100644
--- a/src/codex/catalog/provider-fetch.ts
+++ b/src/codex/catalog/provider-fetch.ts
@@ -1308,7 +1308,11 @@ async function fetchProviderModelsWithAuth(
       ...(cursorFetch ? { fetch: cursorFetch } : {}),
     });
     if (liveResult.ok) {
-      const available = filterCursorConfiguredModelsByLiveDiscovery(configured, liveResult.models);
+      const available = filterCursorConfiguredModelsByLiveDiscovery(
+        configured,
+        liveResult.models,
+        liveResult.maxModeModels ?? [],
+      );
       const result = available.length > 0 ? available : configured;
       // Cache the discovery-filtered roster without combo retention so a later
       // gather can re-apply the current capture's retain set on read.
diff --git a/tests/cursor-ultra-mode.test.ts b/tests/cursor-ultra-mode.test.ts
index a6cbf5bb3a..df6d479a2b 100644
--- a/tests/cursor-ultra-mode.test.ts
+++ b/tests/cursor-ultra-mode.test.ts
@@ -79,13 +79,20 @@ describe("cursor ultra (-1m / Max Mode) toggle (devlog 260826 070)", () => {
     expect(decoded.modelDetails?.maxMode ?? false).toBe(false);
   });
 
-  test("account filter admits the synthetic row through its base availability", () => {
+  test("account filter admits the synthetic row only with base and Max Mode availability", () => {
     const configured = [{ id: "kimi-k3-1m" }, { id: "kimi-k3" }];
     const live = ["kimi-k3-high", "kimi-k3-max"];
-    const filtered = filterCursorConfiguredModelsByLiveDiscovery(configured, live);
+    const filtered = filterCursorConfiguredModelsByLiveDiscovery(configured, live, ["kimi-k3-max"]);
     expect(filtered.map(model => model.id)).toEqual(["kimi-k3-1m", "kimi-k3"]);
   });
 
+  test("account filter hides the synthetic row without discovered Max Mode capability", () => {
+    const configured = [{ id: "kimi-k3-1m" }, { id: "kimi-k3" }];
+    const live = ["kimi-k3-high", "kimi-k3-max"];
+    const filtered = filterCursorConfiguredModelsByLiveDiscovery(configured, live);
+    expect(filtered.map(model => model.id)).toEqual(["kimi-k3"]);
+  });
+
   test("ultra id set stays narrow and every entry has a static row", () => {
     for (const id of CURSOR_ULTRA_1M_MODEL_IDS) {
       expect(CURSOR_STATIC_MODELS.some(model => model.id === id)).toBe(true);