diff --git a/packages/core/src/common/model-capabilities.ts b/packages/core/src/common/model-capabilities.ts
index 59dbc52..c14dc5d 100644
--- a/packages/core/src/common/model-capabilities.ts
+++ b/packages/core/src/common/model-capabilities.ts
@@ -3,6 +3,7 @@ export const DEEPSEEK_V4_MODELS = new Set([
   "deepseek-v4-pro",
   "deepseek-v4-flash-vision-exp",
   "deepseek-flash",
+  "deepseek-ai/deepseek-v4-pro",
 ]);
 
 export type MultimodalMode = "default" | "on" | "off";
diff --git a/packages/core/src/index.ts b/packages/core/src/index.ts
index e045608..a076d9a 100644
--- a/packages/core/src/index.ts
+++ b/packages/core/src/index.ts
@@ -28,6 +28,8 @@ export {
   DEFAULT_FILE_QUOTA_CLEANUP_BATCH,
   DEFAULT_MAX_REQUEST_FILES_BYTES,
   MAX_FILES_API_TIMEOUT_MS,
+  ATLASCLOUD_DEFAULT_MODEL,
+  ATLASCLOUD_BASE_URL,
   PERMISSION_SCOPES,
 } from "./settings";
 export {
diff --git a/packages/core/src/settings.ts b/packages/core/src/settings.ts
index 8dbbf89..8e4ab25 100644
--- a/packages/core/src/settings.ts
+++ b/packages/core/src/settings.ts
@@ -738,6 +738,10 @@ export function resolveSettingsSources(
     ...projectEnv,
     ...systemEnv,
   };
+  const explicitApiKey = trimString(env.API_KEY);
+  const atlasCloudApiKey = trimString(processEnv.ATLASCLOUD_API_KEY);
+  const useAtlasCloudDefaults = !explicitApiKey && Boolean(atlasCloudApiKey);
+
   // Select before normalizing so invalid configured values cannot silently fall back.
   const plusKey =
     systemEnv.PLUS_API_KEY !== undefined
@@ -766,9 +770,9 @@ export function resolveSettingsSources(
       ["user.model", trimString(userSettings?.model) || undefined],
       ["user.env.MODEL", trimString(userEnv.MODEL) || undefined],
     ],
-    defaults.model
+    (useAtlasCloudDefaults ? ATLASCLOUD_DEFAULT_MODEL : "") || defaults.model
   );
-  const baseURL = trimString(env.BASE_URL) || defaults.baseURL;
+  const baseURL = trimString(env.BASE_URL) || (useAtlasCloudDefaults ? ATLASCLOUD_BASE_URL : "") || defaults.baseURL;
 
   const contextWindow = choose(
     "contextWindow",
@@ -1034,7 +1038,7 @@ export function resolveSettingsSources(
   return {
     env,
     experimental: { reasoningSummary, reasoningSummaryModel },
-    apiKey: trimString(env.API_KEY) || undefined,
+    apiKey: explicitApiKey || atlasCloudApiKey || undefined,
     baseURL,
     model,
     contextWindow,
@@ -1124,6 +1128,8 @@ export function applyModelConfigSelection(
 
 export const DEFAULT_MODEL = "deepseek-flash";
 export const DEFAULT_BASE_URL = "https://api.deepseek.com";
+export const ATLASCLOUD_DEFAULT_MODEL = "deepseek-ai/deepseek-v4-pro";
+export const ATLASCLOUD_BASE_URL = "https://api.atlascloud.ai/v1";
 
 // ---------------------------------------------------------------------------
 // Settings file I/O
diff --git a/packages/core/src/tests/settings-and-notify.test.ts b/packages/core/src/tests/settings-and-notify.test.ts
index a5ca060..cb39c63 100644
--- a/packages/core/src/tests/settings-and-notify.test.ts
+++ b/packages/core/src/tests/settings-and-notify.test.ts
@@ -233,6 +233,47 @@ test("resolveSettings gives top-level model priority over env MODEL", () => {
   assert.equal(resolved.model, "deepseek-v4-flash");
 });
 
+test("resolveSettings uses Atlas Cloud defaults with ATLASCLOUD_API_KEY", () => {
+  const resolved = resolveSettings(
+    {},
+    {
+      model: "default-model",
+      baseURL: "https://default.example.com",
+    },
+    {
+      ATLASCLOUD_API_KEY: "atlas-test-key",
+    }
+  );
+
+  assert.equal(resolved.apiKey, "atlas-test-key");
+  assert.equal(resolved.baseURL, "https://api.atlascloud.ai/v1");
+  assert.equal(resolved.model, "deepseek-ai/deepseek-v4-pro");
+  assert.equal(resolved.thinkingEnabled, true);
+});
+
+test("resolveSettings gives explicit API settings priority over Atlas Cloud defaults", () => {
+  const resolved = resolveSettings(
+    {
+      env: {
+        API_KEY: "explicit-key",
+        BASE_URL: "https://explicit.example.com/v1",
+        MODEL: "explicit-model",
+      },
+    },
+    {
+      model: "default-model",
+      baseURL: "https://default.example.com",
+    },
+    {
+      ATLASCLOUD_API_KEY: "atlas-test-key",
+    }
+  );
+
+  assert.equal(resolved.apiKey, "explicit-key");
+  assert.equal(resolved.baseURL, "https://explicit.example.com/v1");
+  assert.equal(resolved.model, "explicit-model");
+});
+
 test("resolveSettings derives model-specific context window defaults", () => {
   const regular = resolveSettings(
     {},