Add SUPPORTED_MODELS to OpenAIResponsesChatGenerator (#10844)

Add a SUPPORTED_MODELS class variable listing supported models
(gpt-5 series, gpt-4.1 series, gpt-4o series, o-series) to
OpenAIResponsesChatGenerator, matching the pattern established
in OpenAIChatGenerator (PR #10736).

Also add a unit test verifying SUPPORTED_MODELS is a non-empty
list of strings.

Closes #10743

Author: ComeOnOliver

haystack/components/generators/chat/openai.py

@@ -6,7 +6,7 @@
 import json
 import os
 from datetime import datetime
-from typing import Any
+from typing import Any, ClassVar
 
 from openai import AsyncOpenAI, AsyncStream, OpenAI, Stream
 from openai.lib._pydantic import to_strict_json_schema
@@ -94,7 +94,7 @@ class OpenAIChatGenerator:
     ```
     """
 
-    SUPPORTED_MODELS = [
+    SUPPORTED_MODELS: ClassVar[list[str]] = [
         "gpt-5-mini",
         "gpt-5-nano",
         "gpt-5",

haystack/components/generators/chat/openai_responses.py

@@ -5,7 +5,7 @@
 import json
 import os
 from datetime import datetime
-from typing import Any
+from typing import Any, ClassVar
 
 from openai import AsyncOpenAI, AsyncStream, OpenAI, Stream
 from openai.lib._pydantic import to_strict_json_schema
@@ -74,6 +74,31 @@ class OpenAIResponsesChatGenerator:
     ```
     """
 
+    SUPPORTED_MODELS: ClassVar[list[str]] = [
+        "gpt-5-mini",
+        "gpt-5-nano",
+        "gpt-5",
+        "gpt-5.1",
+        "gpt-5.2",
+        "gpt-5.2-pro",
+        "gpt-5.4",
+        "gpt-5-pro",
+        "gpt-4.1",
+        "gpt-4.1-mini",
+        "gpt-4.1-nano",
+        "gpt-4o",
+        "gpt-4o-mini",
+        "o1",
+        "o1-mini",
+        "o1-pro",
+        "o3",
+        "o3-mini",
+        "o3-pro",
+        "o4-mini",
+    ]
+    """A non-exhaustive list of chat models supported by this component.
+    See https://platform.openai.com/docs/models for the full list and snapshot IDs."""
+
     def __init__(
         self,
         *,

test/components/generators/chat/test_openai_responses.py

@@ -102,6 +102,13 @@ def __call__(self, chunk: StreamingChunk):
 
 
 class TestInitialization:
+    def test_supported_models(self):
+        """SUPPORTED_MODELS is a non-empty list of strings."""
+        models = OpenAIResponsesChatGenerator.SUPPORTED_MODELS
+        assert isinstance(models, list)
+        assert len(models) > 0
+        assert all(isinstance(m, str) for m in models)
+
     def test_init_default(self, monkeypatch):
         monkeypatch.setenv("OPENAI_API_KEY", "test-api-key")
         component = OpenAIResponsesChatGenerator()