diff --git a/packages/coding-agent/src/core/model-resolver.ts b/packages/coding-agent/src/core/model-resolver.ts
index 0017df00..f4a032c3 100644
--- a/packages/coding-agent/src/core/model-resolver.ts
+++ b/packages/coding-agent/src/core/model-resolver.ts
@@ -15,7 +15,7 @@ export const defaultModelPerProvider: Record<KnownProvider, string> = {
 	"amazon-bedrock": "us.anthropic.claude-opus-4-6-v1",
 	"ant-ling": "Ring-2.6-1T",
 	anthropic: "claude-opus-4-8",
-	openai: "gpt-5.4",
+	openai: "gpt-5.5",
 	"azure-openai-responses": "gpt-5.4",
 	"openai-codex": "gpt-5.5",
 	nvidia: "nvidia/nemotron-3-super-120b-a12b",
diff --git a/packages/coding-agent/test/model-resolver.test.ts b/packages/coding-agent/test/model-resolver.test.ts
index 163c3ab5..9ff02a68 100644
--- a/packages/coding-agent/test/model-resolver.test.ts
+++ b/packages/coding-agent/test/model-resolver.test.ts
@@ -537,7 +537,7 @@ describe("resolveCliModel", () => {
 
 describe("default model selection", () => {
 	test("openai defaults track current models", () => {
-		expect(defaultModelPerProvider.openai).toBe("gpt-5.4");
+		expect(defaultModelPerProvider.openai).toBe("gpt-5.5");
 		expect(defaultModelPerProvider["openai-codex"]).toBe("gpt-5.5");
 	});