diff --git a/packages/core/src/common/model-capabilities.ts b/packages/core/src/common/model-capabilities.ts
index 849cac47..ebc3ab22 100644
--- a/packages/core/src/common/model-capabilities.ts
+++ b/packages/core/src/common/model-capabilities.ts
@@ -1,4 +1,9 @@
-export const DEEPSEEK_V4_MODELS = new Set(["deepseek-v4-flash", "deepseek-v4-pro", "deepseek-v4-flash-vision-exp"]);
+export const DEEPSEEK_V4_MODELS = new Set([
+  "deepseek-v4-flash",
+  "deepseek-v4-pro",
+  "deepseek-v4-flash-vision-exp",
+  "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 5fb2c01f..6501176d 100644
--- a/packages/core/src/index.ts
+++ b/packages/core/src/index.ts
@@ -25,6 +25,8 @@ export {
   DEFAULT_FILE_QUOTA_CLEANUP_BATCH,
   DEFAULT_MAX_REQUEST_FILES_BYTES,
   MAX_FILES_API_TIMEOUT_MS,
+  ATLASCLOUD_DEFAULT_MODEL,
+  ATLASCLOUD_BASE_URL,
 } from "./settings";
 export type {
   DeepcodingSettings,
diff --git a/packages/core/src/settings.ts b/packages/core/src/settings.ts
index 026d8821..8f1f6efa 100644
--- a/packages/core/src/settings.ts
+++ b/packages/core/src/settings.ts
@@ -587,6 +587,9 @@ export function resolveSettingsSources(
     ...projectEnv,
     ...systemEnv,
   };
+  const explicitApiKey = trimString(env.API_KEY);
+  const atlasCloudApiKey = trimString(processEnv.ATLASCLOUD_API_KEY);
+  const useAtlasCloudDefaults = !explicitApiKey && Boolean(atlasCloudApiKey);
 
   const model =
     trimString(systemEnv.MODEL) ||
@@ -594,8 +597,9 @@ export function resolveSettingsSources(
     trimString(projectEnv.MODEL) ||
     trimString(userSettings?.model) ||
     trimString(userEnv.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 =
     firstTokenWindow(systemEnv.CONTEXT_WINDOW, projectSettings?.contextWindow, userSettings?.contextWindow) ??
@@ -700,7 +704,7 @@ export function resolveSettingsSources(
 
   return {
     env,
-    apiKey: trimString(env.API_KEY) || undefined,
+    apiKey: explicitApiKey || atlasCloudApiKey || undefined,
     baseURL,
     model,
     contextWindow,
@@ -770,6 +774,8 @@ export function applyModelConfigSelection(
 
 export const DEFAULT_MODEL = "deepseek-v4-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 6f842438..415198a0 100644
--- a/packages/core/src/tests/settings-and-notify.test.ts
+++ b/packages/core/src/tests/settings-and-notify.test.ts
@@ -232,6 +232,47 @@ 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(
     {},