diff --git a/apps/cli/src/acp/__tests__/model-service.test.ts b/apps/cli/src/acp/__tests__/model-service.test.ts
index d2faf110ce..7931b8b5b1 100644
--- a/apps/cli/src/acp/__tests__/model-service.test.ts
+++ b/apps/cli/src/acp/__tests__/model-service.test.ts
@@ -134,11 +134,7 @@ describe("ModelService", () => {
 			const result = await service.fetchAvailableModels()
 
 			// Should include default model first with actual model name
-			expect(result[0]).toEqual({
-				modelId: "anthropic/claude-sonnet-4.5",
-				name: "Claude Sonnet 4.5",
-				description: "Best balance of speed and capability",
-			})
+			expect(result[0]).toEqual(DEFAULT_MODELS[0])
 
 			// Should include transformed models
 			expect(result.length).toBeGreaterThan(1)
diff --git a/apps/cli/src/acp/types.ts b/apps/cli/src/acp/types.ts
index a6f03fcdea..3a79fb64b3 100644
--- a/apps/cli/src/acp/types.ts
+++ b/apps/cli/src/acp/types.ts
@@ -6,6 +6,8 @@
 
 import type * as acp from "@agentclientprotocol/sdk"
 
+import { DEFAULT_FLAGS } from "@/types/constants.js"
+
 // =============================================================================
 // Model Types
 // =============================================================================
@@ -53,18 +55,19 @@ export interface ExtendedNewSessionResponse extends acp.NewSessionResponse {
 /**
  * Default models available when API is not accessible.
  * These map to Roo Code Cloud model tiers.
+ * The first model uses DEFAULT_FLAGS.model as the source of truth.
  */
 export const DEFAULT_MODELS: AcpModel[] = [
+	{
+		modelId: DEFAULT_FLAGS.model,
+		name: "Claude Sonnet 4.5",
+		description: "Best balance of speed and capability",
+	},
 	{
 		modelId: "anthropic/claude-opus-4.5",
 		name: "Claude Opus 4.5",
 		description: "Most capable for complex work",
 	},
-	{
-		modelId: "anthropic/claude-sonnet-4.5",
-		name: "Claude Sonnet 4.5",
-		description: "Best balance of speed and capability",
-	},
 	{
 		modelId: "anthropic/claude-haiku-4.5",
 		name: "Claude Haiku 4.5",