diff --git a/changelog.d/fixes/11324-skip-full-sync-on-manual-model-add.md b/changelog.d/fixes/11324-skip-full-sync-on-manual-model-add.md
new file mode 100644
index 0000000000..8518e52a93
--- /dev/null
+++ b/changelog.d/fixes/11324-skip-full-sync-on-manual-model-add.md
@@ -0,0 +1 @@
+- **fix(dashboard):** `useApiKeySave.handleSaveApiKey` no longer forces a full upstream `/models` catalog sync on every non-curated provider connection save — callers can now pass `skipModelSync: true` to opt out, so a workflow that only wants to add one manual model no longer floods the provider's available-models list with hundreds/thousands of synced entries. The flag is a client-side intent signal only and is stripped before the connection payload is POSTed to `/api/providers`; default behavior (full sync on save) is unchanged when the flag is omitted (#11324)
diff --git a/src/app/(dashboard)/dashboard/providers/[id]/__tests__/useApiKeySaveSkipsFullSync.test.tsx b/src/app/(dashboard)/dashboard/providers/[id]/__tests__/useApiKeySaveSkipsFullSync.test.tsx
new file mode 100644
index 0000000000..c38c9b4ee5
--- /dev/null
+++ b/src/app/(dashboard)/dashboard/providers/[id]/__tests__/useApiKeySaveSkipsFullSync.test.tsx
@@ -0,0 +1,117 @@
+// @vitest-environment jsdom
+// Regression for issue #11324: adding a custom/manual model connection for a
+// non-curated provider must not force a full upstream /models catalog sync
+// when the caller explicitly opts out via `skipModelSync`.
+import React, { act } from "react";
+import { createRoot } from "react-dom/client";
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+
+import { useApiKeySave } from "../hooks/useApiKeySave";
+
+const t = ((key: string) => key) as Parameters<typeof useApiKeySave>[0]["t"];
+
+function response(ok: boolean, body: unknown): Response {
+  return { ok, json: async () => body } as Response;
+}
+
+function renderApiKeySaveHook(): {
+  hookResult: () => ReturnType<typeof useApiKeySave>;
+  root: ReturnType<typeof createRoot>;
+  container: HTMLDivElement;
+} {
+  const container = document.createElement("div");
+  document.body.appendChild(container);
+  let hookResult: ReturnType<typeof useApiKeySave> | null = null;
+  function Wrapper() {
+    hookResult = useApiKeySave({
+      providerId: "huge-catalog-openai-compatible",
+      fetchConnections: vi.fn().mockResolvedValue(undefined),
+      fetchProviderModelMeta: vi.fn().mockResolvedValue(undefined),
+      setImportProgress: vi.fn(),
+      setShowImportModal: vi.fn(),
+      setShowAddApiKeyModal: vi.fn(),
+      setSiliconFlowInitialBaseUrl: vi.fn(),
+      notify: { success: vi.fn(), error: vi.fn() },
+      t,
+    });
+    return null;
+  }
+  const root = createRoot(container);
+  act(() => root.render(<Wrapper />));
+  return { hookResult: () => hookResult as ReturnType<typeof useApiKeySave>, root, container };
+}
+
+describe("useApiKeySave.handleSaveApiKey — full-sync opt-out (#11324)", () => {
+  let roots: ReturnType<typeof createRoot>[] = [];
+  let containers: HTMLDivElement[] = [];
+
+  beforeEach(() => {
+    (globalThis as any).IS_REACT_ACT_ENVIRONMENT = true;
+    roots = [];
+    containers = [];
+  });
+
+  afterEach(() => {
+    for (const root of roots) act(() => root.unmount());
+    for (const container of containers) container.remove();
+    roots = [];
+    containers = [];
+    vi.unstubAllGlobals();
+  });
+
+  it("does not auto-trigger a full /sync-models catalog fetch when the caller asks to add just one manual model", async () => {
+    const fetchMock = vi.fn(async (input: RequestInfo | URL) => {
+      const url = String(input);
+      if (url === "/api/providers") return response(true, { connection: { id: "conn-1" } });
+      if (url.includes("/sync-models")) {
+        return response(true, {
+          syncedModels: 1200,
+          availableModelsCount: 1200,
+          models: Array.from({ length: 1200 }, (_, i) => ({ id: `model-${i}` })),
+        });
+      }
+      throw new Error(`Unexpected fetch: ${url}`);
+    });
+    vi.stubGlobal("fetch", fetchMock);
+
+    const { hookResult, root, container } = renderApiKeySaveHook();
+    roots.push(root);
+    containers.push(container);
+
+    await act(async () => {
+      await hookResult().handleSaveApiKey({ apiKey: "sk-test", skipModelSync: true });
+    });
+
+    const syncCalls = fetchMock.mock.calls.filter(([input]) => String(input).includes("/sync-models"));
+    expect(syncCalls).toHaveLength(0);
+
+    // The opt-out is a client-side intent signal only — it must never leak into the
+    // persisted connection payload sent to the server.
+    const providersCall = fetchMock.mock.calls.find(([input]) => String(input) === "/api/providers");
+    const postedBody = JSON.parse((providersCall?.[1] as RequestInit).body as string);
+    expect(postedBody).not.toHaveProperty("skipModelSync");
+  });
+
+  it("still auto-triggers the full /sync-models catalog fetch by default (legacy behavior preserved)", async () => {
+    const fetchMock = vi.fn(async (input: RequestInfo | URL) => {
+      const url = String(input);
+      if (url === "/api/providers") return response(true, { connection: { id: "conn-1" } });
+      if (url.includes("/sync-models")) {
+        return response(true, { syncedModels: 3, availableModelsCount: 3, models: [] });
+      }
+      throw new Error(`Unexpected fetch: ${url}`);
+    });
+    vi.stubGlobal("fetch", fetchMock);
+
+    const { hookResult, root, container } = renderApiKeySaveHook();
+    roots.push(root);
+    containers.push(container);
+
+    await act(async () => {
+      await hookResult().handleSaveApiKey({ apiKey: "sk-test" });
+    });
+
+    const syncCalls = fetchMock.mock.calls.filter(([input]) => String(input).includes("/sync-models"));
+    expect(syncCalls).toHaveLength(1);
+  });
+});
diff --git a/src/app/(dashboard)/dashboard/providers/[id]/hooks/useApiKeySave.ts b/src/app/(dashboard)/dashboard/providers/[id]/hooks/useApiKeySave.ts
index 07732aefe6..9ac93a94a9 100644
--- a/src/app/(dashboard)/dashboard/providers/[id]/hooks/useApiKeySave.ts
+++ b/src/app/(dashboard)/dashboard/providers/[id]/hooks/useApiKeySave.ts
@@ -57,13 +57,19 @@ export function useApiKeySave({
 }: UseApiKeySaveParams) {
   const handleSaveApiKey = useCallback(
     async (formData: Record<string, unknown>) => {
+      // Issue #11324: callers that only want to add one manual model (rather than
+      // importing an upstream provider's entire catalog) can pass `skipModelSync: true`
+      // to opt out of the automatic post-save full /sync-models call. This flag is a
+      // client-side intent signal only — strip it before it reaches the connection
+      // creation payload.
+      const { skipModelSync, ...connectionFormData } = formData;
       try {
         const res = await fetch("/api/providers", {
           method: "POST",
           headers: { "Content-Type": "application/json" },
           body: JSON.stringify({
             provider: resolveApiKeySaveProviderId(providerId),
-            ...formData,
+            ...connectionFormData,
           }),
         });
         if (res.ok) {
@@ -75,7 +81,8 @@ export function useApiKeySave({
 
           // Most providers sync their live catalog after connection creation. Curated-only
           // providers intentionally use the registry list and must not show an import flow.
-          if (newConnection?.id && !providerUsesCuratedModelsOnly(providerId)) {
+          // Issue #11324: callers may also opt out explicitly via `skipModelSync`.
+          if (newConnection?.id && !providerUsesCuratedModelsOnly(providerId) && !skipModelSync) {
             setShowImportModal(true);
             setImportProgress({
               current: 0,