diff --git a/.changeset/catalog-builtin-fallback.md b/.changeset/catalog-builtin-fallback.md
new file mode 100644
index 00000000000..712144ec889
--- /dev/null
+++ b/.changeset/catalog-builtin-fallback.md
@@ -0,0 +1,5 @@
+---
+"@moonshot-ai/kimi-code": patch
+---
+
+Fall back to the built-in models.dev catalog snapshot when the public catalog is unreachable, so Known third-party provider import still works offline or in blocked networks.
diff --git a/apps/kimi-code/src/cli/sub/provider.ts b/apps/kimi-code/src/cli/sub/provider.ts
index 3ade36aa422..bb61b0add3d 100644
--- a/apps/kimi-code/src/cli/sub/provider.ts
+++ b/apps/kimi-code/src/cli/sub/provider.ts
@@ -25,7 +25,6 @@ import {
   CatalogFetchError,
   createKimiHarness,
   DEFAULT_CATALOG_URL,
-  fetchCatalog,
   resolveCatalogImport,
   type Catalog,
   type CatalogProviderEntry,
@@ -35,6 +34,7 @@ import {
 import type { Command } from 'commander';
 
 import { createKimiCodeHostIdentity, createKimiCodeUserAgent } from '#/cli/version';
+import { fetchCatalogOrBuiltIn } from '#/utils/catalog-fetch';
 
 interface WritableLike {
   write(chunk: string): boolean;
@@ -434,7 +434,13 @@ export async function handleCatalogAdd(
 
 async function loadCatalogOrExit(deps: ProviderDeps, url: string): Promise<Catalog> {
   try {
-    return await fetchCatalog(url, { userAgent: createKimiCodeUserAgent() });
+    const loaded = await fetchCatalogOrBuiltIn(url, { userAgent: createKimiCodeUserAgent() });
+    if (loaded.fromBuiltIn) {
+      deps.stderr.write(
+        `Warning: failed to reach ${url}; using the built-in models.dev catalog snapshot.\n`,
+      );
+    }
+    return loaded.catalog;
   } catch (error) {
     const suffix = error instanceof CatalogFetchError ? ` (HTTP ${String(error.status)})` : '';
     deps.stderr.write(`Failed to fetch catalog from ${url}${suffix}: ${errorMessage(error)}\n`);
diff --git a/apps/kimi-code/src/tui/commands/provider.ts b/apps/kimi-code/src/tui/commands/provider.ts
index 23bef02ba14..dbfbddfcb2b 100644
--- a/apps/kimi-code/src/tui/commands/provider.ts
+++ b/apps/kimi-code/src/tui/commands/provider.ts
@@ -9,13 +9,13 @@ import {
   catalogProviderModels,
   CatalogFetchError,
   DEFAULT_CATALOG_URL,
-  fetchCatalog,
   resolveCatalogImport,
   type Catalog,
   type ThinkingEffort,
 } from '@moonshot-ai/kimi-code-sdk';
 
 import { createKimiCodeUserAgent } from '#/cli/version';
+import { fetchCatalogOrBuiltIn } from '#/utils/catalog-fetch';
 import { ChoicePickerComponent } from '../components/dialogs/choice-picker';
 import {
   CustomRegistryImportDialogComponent,
@@ -162,11 +162,17 @@ async function handleCatalogProviderAdd(host: SlashCommandHost): Promise<void> {
   const spinner = host.showLoginProgressSpinner(`Fetching catalog from ${DEFAULT_CATALOG_URL}`);
   let catalog: Catalog | undefined;
   try {
-    catalog = await fetchCatalog(DEFAULT_CATALOG_URL, {
+    const loaded = await fetchCatalogOrBuiltIn(DEFAULT_CATALOG_URL, {
       signal: controller.signal,
       userAgent: createKimiCodeUserAgent(),
     });
-    spinner.stop({ ok: true, label: 'Catalog loaded.' });
+    catalog = loaded.catalog;
+    spinner.stop({
+      ok: true,
+      label: loaded.fromBuiltIn
+        ? 'Catalog loaded from built-in snapshot (models.dev unreachable).'
+        : 'Catalog loaded.',
+    });
   } catch (error) {
     if (controller.signal.aborted) {
       spinner.stop({ ok: false, label: 'Aborted.' });
diff --git a/apps/kimi-code/src/utils/catalog-fetch.ts b/apps/kimi-code/src/utils/catalog-fetch.ts
new file mode 100644
index 00000000000..0f3ffdddfb8
--- /dev/null
+++ b/apps/kimi-code/src/utils/catalog-fetch.ts
@@ -0,0 +1,57 @@
+import {
+  DEFAULT_CATALOG_URL,
+  fetchCatalog,
+  loadBuiltInCatalog,
+  type Catalog,
+  type FetchCatalogOptions,
+} from '@moonshot-ai/kimi-code-sdk';
+
+import { BUILT_IN_CATALOG_JSON } from '#/built-in-catalog';
+
+export interface FetchCatalogOrBuiltInResult {
+  readonly catalog: Catalog;
+  /** True when the network fetch failed and the release-build snapshot was used. */
+  readonly fromBuiltIn: boolean;
+}
+
+export interface FetchCatalogOrBuiltInOptions extends FetchCatalogOptions {
+  /**
+   * Override the built-in snapshot JSON (tests). Defaults to the tsdown-injected
+   * `__KIMI_CODE_BUILT_IN_CATALOG__` constant.
+   */
+  readonly builtInJson?: string;
+}
+
+/**
+ * Fetches a models.dev-style catalog, falling back to the release-build
+ * snapshot when the public default URL is unreachable.
+ *
+ * Custom `--url` overrides never fall back — a private registry must fail
+ * loudly rather than silently substitute models.dev. User abort
+ * (`signal.aborted`) also skips the fallback so Cancel stays Cancel.
+ */
+export async function fetchCatalogOrBuiltIn(
+  url: string,
+  options: FetchCatalogOrBuiltInOptions = {},
+): Promise<FetchCatalogOrBuiltInResult> {
+  try {
+    const catalog = await fetchCatalog(url, options);
+    return { catalog, fromBuiltIn: false };
+  } catch (error) {
+    if (options.signal?.aborted) throw error;
+    if (isAbortError(error)) throw error;
+    if (url !== DEFAULT_CATALOG_URL) throw error;
+    const builtIn = loadBuiltInCatalog(options.builtInJson ?? BUILT_IN_CATALOG_JSON);
+    if (builtIn === undefined) throw error;
+    return { catalog: builtIn, fromBuiltIn: true };
+  }
+}
+
+function isAbortError(error: unknown): boolean {
+  return (
+    (typeof DOMException !== 'undefined' &&
+      error instanceof DOMException &&
+      error.name === 'AbortError') ||
+    (error instanceof Error && error.name === 'AbortError')
+  );
+}
diff --git a/apps/kimi-code/test/utils/catalog-fetch.test.ts b/apps/kimi-code/test/utils/catalog-fetch.test.ts
new file mode 100644
index 00000000000..e609df88722
--- /dev/null
+++ b/apps/kimi-code/test/utils/catalog-fetch.test.ts
@@ -0,0 +1,84 @@
+import { DEFAULT_CATALOG_URL, CatalogFetchError } from '@moonshot-ai/kimi-code-sdk';
+import { describe, expect, it, vi } from 'vitest';
+
+import { fetchCatalogOrBuiltIn } from '#/utils/catalog-fetch';
+
+const BUILT_IN = JSON.stringify({
+  anthropic: {
+    id: 'anthropic',
+    name: 'Anthropic',
+    models: { 'claude-test': { id: 'claude-test', limit: { context: 200000 } } },
+  },
+});
+
+function jsonResponse(body: unknown, status = 200): Response {
+  return new Response(JSON.stringify(body), {
+    status,
+    headers: { 'Content-Type': 'application/json' },
+  });
+}
+
+describe('fetchCatalogOrBuiltIn', () => {
+  it('returns the network catalog when models.dev is reachable', async () => {
+    const network = { openai: { id: 'openai', models: {} } };
+    const fetchImpl = vi.fn(async () => jsonResponse(network));
+
+    const result = await fetchCatalogOrBuiltIn(DEFAULT_CATALOG_URL, {
+      fetchImpl: fetchImpl as unknown as typeof fetch,
+      builtInJson: BUILT_IN,
+    });
+
+    expect(result.fromBuiltIn).toBe(false);
+    expect(result.catalog).toEqual(network);
+  });
+
+  it('falls back to the built-in snapshot when the default URL fetch fails', async () => {
+    const fetchImpl = vi.fn(async () => jsonResponse('no', 503));
+
+    const result = await fetchCatalogOrBuiltIn(DEFAULT_CATALOG_URL, {
+      fetchImpl: fetchImpl as unknown as typeof fetch,
+      builtInJson: BUILT_IN,
+    });
+
+    expect(result.fromBuiltIn).toBe(true);
+    expect(result.catalog).toEqual(JSON.parse(BUILT_IN));
+  });
+
+  it('does not fall back for a custom catalog URL', async () => {
+    const fetchImpl = vi.fn(async () => jsonResponse('no', 500));
+
+    await expect(
+      fetchCatalogOrBuiltIn('https://example.test/private.json', {
+        fetchImpl: fetchImpl as unknown as typeof fetch,
+        builtInJson: BUILT_IN,
+      }),
+    ).rejects.toBeInstanceOf(CatalogFetchError);
+  });
+
+  it('does not fall back when the caller aborted the request', async () => {
+    const controller = new AbortController();
+    controller.abort();
+    const fetchImpl = vi.fn(async () => {
+      throw new DOMException('Aborted', 'AbortError');
+    });
+
+    await expect(
+      fetchCatalogOrBuiltIn(DEFAULT_CATALOG_URL, {
+        signal: controller.signal,
+        fetchImpl: fetchImpl as unknown as typeof fetch,
+        builtInJson: BUILT_IN,
+      }),
+    ).rejects.toThrow();
+  });
+
+  it('rethrows when fetch fails and no built-in snapshot is available', async () => {
+    const fetchImpl = vi.fn(async () => jsonResponse('no', 500));
+
+    await expect(
+      fetchCatalogOrBuiltIn(DEFAULT_CATALOG_URL, {
+        fetchImpl: fetchImpl as unknown as typeof fetch,
+        builtInJson: '',
+      }),
+    ).rejects.toBeInstanceOf(CatalogFetchError);
+  });
+});
diff --git a/packages/node-sdk/test/catalog.test.ts b/packages/node-sdk/test/catalog.test.ts
index d1bc5a6ea9a..30bb7d01e61 100644
--- a/packages/node-sdk/test/catalog.test.ts
+++ b/packages/node-sdk/test/catalog.test.ts
@@ -7,6 +7,7 @@ import {
   catalogProviderModels,
   CatalogFetchError,
   fetchCatalog,
+  loadBuiltInCatalog,
   type CatalogModel,
 } from '../src/catalog';
 
@@ -79,6 +80,19 @@ describe('fetchCatalog', () => {
   });
 });
 
+describe('loadBuiltInCatalog', () => {
+  it('parses a valid catalog JSON string', () => {
+    const catalog = { anthropic: { id: 'anthropic', models: {} } };
+    expect(loadBuiltInCatalog(JSON.stringify(catalog))).toEqual(catalog);
+  });
+
+  it('returns undefined for missing or invalid input', () => {
+    expect(loadBuiltInCatalog(undefined)).toBeUndefined();
+    expect(loadBuiltInCatalog('')).toBeUndefined();
+    expect(loadBuiltInCatalog('not-json')).toBeUndefined();
+  });
+});
+
 describe('catalogModelToAlias', () => {
   it('flattens a catalog model capability into alias fields', () => {
     expect(catalogModelToAlias('anthropic', model)).toEqual({