diff --git a/lib/accounts.ts b/lib/accounts.ts
index 2e4a294..87060ba 100644
--- a/lib/accounts.ts
+++ b/lib/accounts.ts
@@ -297,6 +297,7 @@ export class AccountManager {
 	private accounts: ManagedAccount[] = [];
 	private cursor = 0;
 	private currentAccountIndexByFamily: Record<ModelFamily, number> = {
+		"gpt-5.3-codex": -1,
 		"gpt-5.2-codex": -1,
 		"codex-max": -1,
 		codex: -1,
@@ -304,6 +305,7 @@ export class AccountManager {
 		"gpt-5.1": -1,
 	};
 	private sessionOffsetApplied: Record<ModelFamily, boolean> = {
+		"gpt-5.3-codex": false,
 		"gpt-5.2-codex": false,
 		"codex-max": false,
 		codex: false,
diff --git a/lib/constants.ts b/lib/constants.ts
index de78e17..76f4b73 100644
--- a/lib/constants.ts
+++ b/lib/constants.ts
@@ -82,6 +82,7 @@ export const AUTH_LABELS = {
 
 /** Model family identifiers for account selection */
 export const MODEL_FAMILIES = [
+	"gpt-5.3-codex",
 	"gpt-5.2-codex",
 	"codex-max",
 	"codex",
diff --git a/lib/prompts/codex.ts b/lib/prompts/codex.ts
index 228dac7..6922d94 100644
--- a/lib/prompts/codex.ts
+++ b/lib/prompts/codex.ts
@@ -21,6 +21,7 @@ const __dirname = dirname(__filename);
  * Based on codex-rs/core/src/model_family.rs logic
  */
 const PROMPT_FILES: Record<ModelFamily, string> = {
+	"gpt-5.3-codex": "gpt-5.2-codex_prompt.md",
 	"gpt-5.2-codex": "gpt-5.2-codex_prompt.md",
 	"codex-max": "gpt-5.1-codex-max_prompt.md",
 	codex: "gpt_5_codex_prompt.md",
@@ -32,6 +33,7 @@ const PROMPT_FILES: Record<ModelFamily, string> = {
  * Cache file mapping for each model family
  */
 const CACHE_FILES: Record<ModelFamily, string> = {
+	"gpt-5.3-codex": "gpt-5.2-codex-instructions.md",
 	"gpt-5.2-codex": "gpt-5.2-codex-instructions.md",
 	"codex-max": "codex-max-instructions.md",
 	codex: "codex-instructions.md",
@@ -58,6 +60,12 @@ function ensureCacheMigrated(): void {
  */
 export function getModelFamily(normalizedModel: string): ModelFamily {
 	// Order matters - check more specific patterns first
+	if (
+		normalizedModel.includes("gpt-5.3-codex") ||
+		normalizedModel.includes("gpt 5.3 codex")
+	) {
+		return "gpt-5.3-codex";
+	}
 	if (
 		normalizedModel.includes("gpt-5.2-codex") ||
 		normalizedModel.includes("gpt 5.2 codex")