diff --git a/docs/concepts/unified-interface.md b/docs/concepts/unified-interface.md
index 55d9d4fc..db1b793d 100644
--- a/docs/concepts/unified-interface.md
+++ b/docs/concepts/unified-interface.md
@@ -61,6 +61,8 @@ The only required change is model selection. Everything else stays unchanged.
 
 | Model | Alias |
 |---|---|
+| GPT-5.4 | `gpt-5.4` |
+| GPT-5.4 Pro | `gpt-5.4-pro` |
 | GPT-5.3 Codex | `gpt-5.3-codex` |
 | GPT-5.3 Codex Spark | `gpt-5.3-codex-spark` |
 | GPT-5.2 Codex | `gpt-5.2-codex` |
@@ -76,7 +78,7 @@ The only required change is model selection. Everything else stays unchanged.
 Locus infers the provider from the model name:
 
 1. Known Claude aliases (`opus`, `sonnet`, `haiku`) → Claude
-2. Known Codex aliases → Codex
+2. Known Codex models (`gpt-5.4`, `gpt-5.4-pro`, `gpt-5.3-codex`, etc.) → Codex
 3. Model name starts with `claude-` → Claude
 4. Model name contains `codex` → Codex
 
diff --git a/packages/cli/__tests__/codex-runner.test.ts b/packages/cli/__tests__/codex-runner.test.ts
index 5f0fffb5..5c39335f 100644
--- a/packages/cli/__tests__/codex-runner.test.ts
+++ b/packages/cli/__tests__/codex-runner.test.ts
@@ -20,4 +20,20 @@ describe("buildCodexArgs", () => {
     expect(args).not.toContain("--approval-mode");
     expect(args.at(-1)).toBe("-");
   });
+
+  test("includes gpt-5.4 model", () => {
+    const args = buildCodexArgs("gpt-5.4");
+
+    expect(args).toContain("--model");
+    expect(args).toContain("gpt-5.4");
+    expect(args.at(-1)).toBe("-");
+  });
+
+  test("includes gpt-5.4-pro model", () => {
+    const args = buildCodexArgs("gpt-5.4-pro");
+
+    expect(args).toContain("--model");
+    expect(args).toContain("gpt-5.4-pro");
+    expect(args.at(-1)).toBe("-");
+  });
 });
diff --git a/packages/cli/__tests__/config.test.ts b/packages/cli/__tests__/config.test.ts
index be715396..9aaccedb 100644
--- a/packages/cli/__tests__/config.test.ts
+++ b/packages/cli/__tests__/config.test.ts
@@ -118,6 +118,17 @@ describe("config", () => {
       expect(config.ai.provider).toBe("codex");
       expect(config.ai.model).toBe("gpt-5.3-codex");
     });
+
+    it("infers codex provider from gpt-5.4 model on load", () => {
+      setupProject({
+        version: "3.0.0",
+        github: { owner: "custom", repo: "mine", defaultBranch: "develop" },
+        ai: { provider: "claude", model: "gpt-5.4" },
+      });
+      const config = loadConfig(TEST_DIR);
+      expect(config.ai.provider).toBe("codex");
+      expect(config.ai.model).toBe("gpt-5.4");
+    });
   });
 
   describe("saveConfig", () => {
@@ -175,6 +186,20 @@ describe("config", () => {
       expect(updated.ai.provider).toBe("codex");
     });
 
+    it("updates provider when model changes to gpt-5.4", () => {
+      setupProject();
+      const updated = updateConfigValue(TEST_DIR, "ai.model", "gpt-5.4");
+      expect(updated.ai.model).toBe("gpt-5.4");
+      expect(updated.ai.provider).toBe("codex");
+    });
+
+    it("updates provider when model changes to gpt-5.4-pro", () => {
+      setupProject();
+      const updated = updateConfigValue(TEST_DIR, "ai.model", "gpt-5.4-pro");
+      expect(updated.ai.model).toBe("gpt-5.4-pro");
+      expect(updated.ai.provider).toBe("codex");
+    });
+
     it("auto-coerces string 'true' to boolean", () => {
       setupProject();
       const updated = updateConfigValue(TEST_DIR, "agent.autoLabel", "false");
diff --git a/packages/cli/__tests__/repl-model-config.test.ts b/packages/cli/__tests__/repl-model-config.test.ts
index b6e3388b..7ef66836 100644
--- a/packages/cli/__tests__/repl-model-config.test.ts
+++ b/packages/cli/__tests__/repl-model-config.test.ts
@@ -43,4 +43,17 @@ describe("repl model config persistence", () => {
     expect(reloaded.ai.model).toBe("gpt-5.3-codex");
     expect(reloaded.ai.provider).toBe("codex");
   });
+
+  it("persists gpt-5.4 model and infers codex provider", () => {
+    const inMemoryConfig = loadConfig(TEST_DIR);
+
+    persistReplModelSelection(TEST_DIR, inMemoryConfig, "gpt-5.4");
+
+    expect(inMemoryConfig.ai.model).toBe("gpt-5.4");
+    expect(inMemoryConfig.ai.provider).toBe("codex");
+
+    const reloaded = loadConfig(TEST_DIR);
+    expect(reloaded.ai.model).toBe("gpt-5.4");
+    expect(reloaded.ai.provider).toBe("codex");
+  });
 });
diff --git a/packages/cli/src/core/ai-models.ts b/packages/cli/src/core/ai-models.ts
index b12890f8..7cd7f3ab 100644
--- a/packages/cli/src/core/ai-models.ts
+++ b/packages/cli/src/core/ai-models.ts
@@ -13,6 +13,8 @@ const CLAUDE_MODELS = [
 ] as const;
 
 const CODEX_MODELS = [
+  "gpt-5.4",
+  "gpt-5.4-pro",
   "gpt-5.3-codex",
   "gpt-5.3-codex-spark",
   "gpt-5.2-codex",