fix: correct model name gpt-5.1-mini to gpt-5.1-codex-mini

Fixes #2785

The model string `gpt-5.1-mini` was incorrectly listed in the ChatModel type.
It should be `gpt-5.1-codex-mini` to match the actual model naming.

Changes:
- Updated gpt-5.1-mini to gpt-5.1-codex-mini in:
  - src/openai/types/shared/chat_model.py
  - src/openai/types/shared_params/chat_model.py
  - src/openai/resources/responses/responses.py
  - src/openai/types/responses/response_compact_params.py
- Added test to verify the correct model name

Author: majiayu000

src/openai/resources/responses/responses.py

@@ -1536,7 +1536,7 @@ def compact(
                 "gpt-5.1",
                 "gpt-5.1-2025-11-13",
                 "gpt-5.1-codex",
-                "gpt-5.1-mini",
+                "gpt-5.1-codex-mini",
                 "gpt-5.1-chat-latest",
                 "gpt-5",
                 "gpt-5-mini",
@@ -3154,7 +3154,7 @@ async def compact(
                 "gpt-5.1",
                 "gpt-5.1-2025-11-13",
                 "gpt-5.1-codex",
-                "gpt-5.1-mini",
+                "gpt-5.1-codex-mini",
                 "gpt-5.1-chat-latest",
                 "gpt-5",
                 "gpt-5-mini",

src/openai/types/responses/response_compact_params.py

@@ -22,7 +22,7 @@ class ResponseCompactParams(TypedDict, total=False):
                 "gpt-5.1",
                 "gpt-5.1-2025-11-13",
                 "gpt-5.1-codex",
-                "gpt-5.1-mini",
+                "gpt-5.1-codex-mini",
                 "gpt-5.1-chat-latest",
                 "gpt-5",
                 "gpt-5-mini",

src/openai/types/shared/chat_model.py

@@ -13,7 +13,7 @@
     "gpt-5.1",
     "gpt-5.1-2025-11-13",
     "gpt-5.1-codex",
-    "gpt-5.1-mini",
+    "gpt-5.1-codex-mini",
     "gpt-5.1-chat-latest",
     "gpt-5",
     "gpt-5-mini",

src/openai/types/shared_params/chat_model.py

@@ -15,7 +15,7 @@
     "gpt-5.1",
     "gpt-5.1-2025-11-13",
     "gpt-5.1-codex",
-    "gpt-5.1-mini",
+    "gpt-5.1-codex-mini",
     "gpt-5.1-chat-latest",
     "gpt-5",
     "gpt-5-mini",

tests/test_chat_model_types.py

@@ -0,0 +1,55 @@
+"""Tests for ChatModel type definitions.
+
+Verifies that the ChatModel type includes correct model names.
+Relates to issue #2785: GPT 5.1 Mini wrongly listed in model list
+"""
+
+import pytest
+from typing import get_args
+
+from openai.types.shared import ChatModel
+
+
+class TestChatModelTypes:
+    """Test ChatModel type definitions."""
+
+    def test_gpt_5_1_codex_mini_exists(self) -> None:
+        """Verify gpt-5.1-codex-mini is in ChatModel (fixes #2785)."""
+        # Get all valid ChatModel values
+        valid_models = get_args(ChatModel)
+
+        # gpt-5.1-codex-mini should exist (not gpt-5.1-mini)
+        assert "gpt-5.1-codex-mini" in valid_models, (
+            "gpt-5.1-codex-mini should be in ChatModel"
+        )
+
+    def test_gpt_5_1_mini_not_exists(self) -> None:
+        """Verify gpt-5.1-mini is NOT in ChatModel (was incorrect)."""
+        valid_models = get_args(ChatModel)
+
+        # gpt-5.1-mini should NOT exist (it was wrongly listed)
+        assert "gpt-5.1-mini" not in valid_models, (
+            "gpt-5.1-mini should NOT be in ChatModel (issue #2785)"
+        )
+
+    def test_gpt_5_1_codex_exists(self) -> None:
+        """Verify gpt-5.1-codex is in ChatModel."""
+        valid_models = get_args(ChatModel)
+        assert "gpt-5.1-codex" in valid_models
+
+    def test_gpt_5_family_models_exist(self) -> None:
+        """Verify GPT-5 family models are present."""
+        valid_models = get_args(ChatModel)
+
+        expected_gpt5_models = [
+            "gpt-5",
+            "gpt-5-mini",
+            "gpt-5-nano",
+            "gpt-5.1",
+            "gpt-5.1-codex",
+            "gpt-5.1-codex-mini",
+            "gpt-5.2",
+        ]
+
+        for model in expected_gpt5_models:
+            assert model in valid_models, f"{model} should be in ChatModel"