diff --git a/packages/ai/scripts/generate-models.ts b/packages/ai/scripts/generate-models.ts
index 66b36f8c..0e84e7c9 100644
--- a/packages/ai/scripts/generate-models.ts
+++ b/packages/ai/scripts/generate-models.ts
@@ -647,7 +647,10 @@ async function generateModels() {
 	const aiGatewayModels = await fetchAiGatewayModels();
 
 	// Combine models (models.dev has priority)
-	const allModels = [...modelsDevModels, ...openRouterModels, ...aiGatewayModels];
+	const allModels = [...modelsDevModels, ...openRouterModels, ...aiGatewayModels].filter(
+		(model) =>
+			!((model.provider === "opencode" || model.provider === "opencode-go") && model.id === "gpt-5.3-codex-spark"),
+	);
 
 	// Fix incorrect cache pricing for Claude Opus 4.5 from models.dev
 	// models.dev has 3x the correct pricing (1.5/18.75 instead of 0.5/6.25)
@@ -677,8 +680,29 @@ async function generateModels() {
 		) {
 			candidate.contextWindow = 200000;
 		}
+		if ((candidate.provider === "opencode" || candidate.provider === "opencode-go") && candidate.id === "gpt-5.4") {
+			candidate.contextWindow = 272000;
+			candidate.maxTokens = 128000;
+		}
+		if (candidate.provider === "openai" && candidate.id === "gpt-5.4") {
+			candidate.contextWindow = 272000;
+			candidate.maxTokens = 128000;
+		}
+		// Keep selected OpenRouter model metadata stable until upstream settles.
+		if (candidate.provider === "openrouter" && candidate.id === "moonshotai/kimi-k2.5") {
+			candidate.cost.input = 0.41;
+			candidate.cost.output = 2.06;
+			candidate.cost.cacheRead = 0.07;
+			candidate.maxTokens = 4096;
+		}
+		if (candidate.provider === "openrouter" && candidate.id === "z-ai/glm-5") {
+			candidate.cost.input = 0.6;
+			candidate.cost.output = 1.9;
+			candidate.cost.cacheRead = 0.119;
+		}
 	}
 
+
 	// Add missing EU Opus 4.6 profile
 	if (!allModels.some((m) => m.provider === "amazon-bedrock" && m.id === "eu.anthropic.claude-opus-4-6-v1")) {
 		allModels.push({
@@ -858,6 +882,26 @@ async function generateModels() {
 		}
 	}
 
+	if (!allModels.some((m) => m.provider === "openai" && m.id === "gpt-5.4")) {
+		allModels.push({
+			id: "gpt-5.4",
+			name: "GPT-5.4",
+			api: "openai-responses",
+			baseUrl: "https://api.openai.com/v1",
+			provider: "openai",
+			reasoning: true,
+			input: ["text", "image"],
+			cost: {
+				input: 2.5,
+				output: 15,
+				cacheRead: 0.25,
+				cacheWrite: 0,
+			},
+			contextWindow: 272000,
+			maxTokens: 128000,
+		});
+	}
+
 	// OpenAI Codex (ChatGPT OAuth) models
 	// NOTE: These are not fetched from models.dev; we keep a small, explicit list to avoid aliases.
 	// Context window is based on observed server limits (400s above ~272k), not marketing numbers.
@@ -937,6 +981,18 @@ async function generateModels() {
 			contextWindow: CODEX_CONTEXT,
 			maxTokens: CODEX_MAX_TOKENS,
 		},
+		{
+			id: "gpt-5.4",
+			name: "GPT-5.4",
+			api: "openai-codex-responses",
+			provider: "openai-codex",
+			baseUrl: CODEX_BASE_URL,
+			reasoning: true,
+			input: ["text", "image"],
+			cost: { input: 2.5, output: 15, cacheRead: 0.25, cacheWrite: 0 },
+			contextWindow: CODEX_CONTEXT,
+			maxTokens: CODEX_MAX_TOKENS,
+		},
 		{
 			id: "gpt-5.3-codex-spark",
 			name: "GPT-5.3 Codex Spark",
diff --git a/packages/ai/src/models.generated.ts b/packages/ai/src/models.generated.ts
index 4850e666..32747153 100644
--- a/packages/ai/src/models.generated.ts
+++ b/packages/ai/src/models.generated.ts
@@ -2287,6 +2287,23 @@ export const MODELS = {
 			contextWindow: 128000,
 			maxTokens: 32000,
 		} satisfies Model<"azure-openai-responses">,
+		"gpt-5.4": {
+			id: "gpt-5.4",
+			name: "GPT-5.4",
+			api: "azure-openai-responses",
+			provider: "azure-openai-responses",
+			baseUrl: "",
+			reasoning: true,
+			input: ["text", "image"],
+			cost: {
+				input: 2.5,
+				output: 15,
+				cacheRead: 0.25,
+				cacheWrite: 0,
+			},
+			contextWindow: 272000,
+			maxTokens: 128000,
+		} satisfies Model<"azure-openai-responses">,
 		"o1": {
 			id: "o1",
 			name: "o1",
@@ -5420,6 +5437,23 @@ export const MODELS = {
 			contextWindow: 128000,
 			maxTokens: 32000,
 		} satisfies Model<"openai-responses">,
+		"gpt-5.4": {
+			id: "gpt-5.4",
+			name: "GPT-5.4",
+			api: "openai-responses",
+			provider: "openai",
+			baseUrl: "https://api.openai.com/v1",
+			reasoning: true,
+			input: ["text", "image"],
+			cost: {
+				input: 2.5,
+				output: 15,
+				cacheRead: 0.25,
+				cacheWrite: 0,
+			},
+			contextWindow: 272000,
+			maxTokens: 128000,
+		} satisfies Model<"openai-responses">,
 		"o1": {
 			id: "o1",
 			name: "o1",
@@ -5677,6 +5711,23 @@ export const MODELS = {
 			contextWindow: 128000,
 			maxTokens: 128000,
 		} satisfies Model<"openai-codex-responses">,
+		"gpt-5.4": {
+			id: "gpt-5.4",
+			name: "GPT-5.4",
+			api: "openai-codex-responses",
+			provider: "openai-codex",
+			baseUrl: "https://chatgpt.com/backend-api",
+			reasoning: true,
+			input: ["text", "image"],
+			cost: {
+				input: 2.5,
+				output: 15,
+				cacheRead: 0.25,
+				cacheWrite: 0,
+			},
+			contextWindow: 272000,
+			maxTokens: 128000,
+		} satisfies Model<"openai-codex-responses">,
 	},
 	"opencode": {
 		"big-pickle": {
@@ -6118,7 +6169,7 @@ export const MODELS = {
 				cacheRead: 0.25,
 				cacheWrite: 0,
 			},
-			contextWindow: 1050000,
+			contextWindow: 272000,
 			maxTokens: 128000,
 		} satisfies Model<"openai-responses">,
 		"kimi-k2.5": {
diff --git a/packages/ai/src/models.ts b/packages/ai/src/models.ts
index 459b1be2..3c06c0cc 100644
--- a/packages/ai/src/models.ts
+++ b/packages/ai/src/models.ts
@@ -49,11 +49,11 @@ export function calculateCost<TApi extends Api>(model: Model<TApi>, usage: Usage
  * Check if a model supports xhigh thinking level.
  *
  * Supported today:
- * - GPT-5.2 / GPT-5.3 model families
+ * - GPT-5.2 / GPT-5.3 / GPT-5.4 model families
  * - Anthropic Messages API Opus 4.6 models (xhigh maps to adaptive effort "max")
  */
 export function supportsXhigh<TApi extends Api>(model: Model<TApi>): boolean {
-	if (model.id.includes("gpt-5.2") || model.id.includes("gpt-5.3")) {
+	if (model.id.includes("gpt-5.2") || model.id.includes("gpt-5.3") || model.id.includes("gpt-5.4")) {
 		return true;
 	}
 
diff --git a/packages/ai/src/providers/openai-codex-responses.ts b/packages/ai/src/providers/openai-codex-responses.ts
index 96de4cc7..90ec3ecd 100644
--- a/packages/ai/src/providers/openai-codex-responses.ts
+++ b/packages/ai/src/providers/openai-codex-responses.ts
@@ -324,7 +324,8 @@ function buildRequestBody(
 
 function clampReasoningEffort(modelId: string, effort: string): string {
 	const id = modelId.includes("/") ? modelId.split("/").pop()! : modelId;
-	if ((id.startsWith("gpt-5.2") || id.startsWith("gpt-5.3")) && effort === "minimal") return "low";
+	if ((id.startsWith("gpt-5.2") || id.startsWith("gpt-5.3") || id.startsWith("gpt-5.4")) && effort === "minimal")
+		return "low";
 	if (id === "gpt-5.1" && effort === "xhigh") return "high";
 	if (id === "gpt-5.1-codex-mini") return effort === "high" || effort === "xhigh" ? "high" : "medium";
 	return effort;
diff --git a/packages/ai/test/openai-codex-stream.test.ts b/packages/ai/test/openai-codex-stream.test.ts
index 8f7685cf..2220c398 100644
--- a/packages/ai/test/openai-codex-stream.test.ts
+++ b/packages/ai/test/openai-codex-stream.test.ts
@@ -231,7 +231,7 @@ describe("openai-codex streaming", () => {
 		await streamResult.result();
 	});
 
-	it("clamps gpt-5.3-codex minimal reasoning effort to low", async () => {
+	it.each(["gpt-5.3-codex", "gpt-5.4"])("clamps %s minimal reasoning effort to low", async (modelId) => {
 		const tempDir = mkdtempSync(join(tmpdir(), "pi-codex-stream-"));
 		process.env.PI_CODING_AGENT_DIR = tempDir;
 
@@ -303,8 +303,8 @@ describe("openai-codex streaming", () => {
 		global.fetch = fetchMock as typeof fetch;
 
 		const model: Model<"openai-codex-responses"> = {
-			id: "gpt-5.3-codex",
-			name: "GPT-5.3 Codex",
+			id: modelId,
+			name: modelId,
 			api: "openai-codex-responses",
 			provider: "openai-codex",
 			baseUrl: "https://chatgpt.com/backend-api",
diff --git a/packages/ai/test/supports-xhigh.test.ts b/packages/ai/test/supports-xhigh.test.ts
index d740e778..e7bc5aa6 100644
--- a/packages/ai/test/supports-xhigh.test.ts
+++ b/packages/ai/test/supports-xhigh.test.ts
@@ -14,6 +14,12 @@ describe("supportsXhigh", () => {
 		expect(supportsXhigh(model!)).toBe(false);
 	});
 
+	it("returns true for GPT-5.4 models", () => {
+		const model = getModel("openai-codex", "gpt-5.4");
+		expect(model).toBeDefined();
+		expect(supportsXhigh(model!)).toBe(true);
+	});
+
 	it("returns false for OpenRouter Opus 4.6 (openai-completions API)", () => {
 		const model = getModel("openrouter", "anthropic/claude-opus-4.6");
 		expect(model).toBeDefined();
diff --git a/packages/coding-agent/src/core/model-resolver.ts b/packages/coding-agent/src/core/model-resolver.ts
index 9549f81b..b0e7743f 100644
--- a/packages/coding-agent/src/core/model-resolver.ts
+++ b/packages/coding-agent/src/core/model-resolver.ts
@@ -14,9 +14,9 @@ import type { ModelRegistry } from "./model-registry.js";
 export const defaultModelPerProvider: Record<KnownProvider, string> = {
 	"amazon-bedrock": "us.anthropic.claude-opus-4-6-v1",
 	anthropic: "claude-opus-4-6",
-	openai: "gpt-5.1-codex",
+	openai: "gpt-5.4",
 	"azure-openai-responses": "gpt-5.2",
-	"openai-codex": "gpt-5.3-codex",
+	"openai-codex": "gpt-5.4",
 	google: "gemini-2.5-pro",
 	"google-gemini-cli": "gemini-2.5-pro",
 	"google-antigravity": "gemini-3.1-pro-high",
diff --git a/packages/coding-agent/test/model-resolver.test.ts b/packages/coding-agent/test/model-resolver.test.ts
index 3f3ab977..70eeb7bd 100644
--- a/packages/coding-agent/test/model-resolver.test.ts
+++ b/packages/coding-agent/test/model-resolver.test.ts
@@ -373,6 +373,11 @@ describe("resolveCliModel", () => {
 });
 
 describe("default model selection", () => {
+	test("openai defaults are gpt-5.4", () => {
+		expect(defaultModelPerProvider.openai).toBe("gpt-5.4");
+		expect(defaultModelPerProvider["openai-codex"]).toBe("gpt-5.4");
+	});
+
 	test("ai-gateway default is opus 4.6", () => {
 		expect(defaultModelPerProvider["vercel-ai-gateway"]).toBe("anthropic/claude-opus-4-6");
 	});