Add OpenAI's GPT-5.4 model (qodo-ai#2247)

Rererence:
- https://openai.com/index/introducing-gpt-5-4/
- https://developers.openai.com/api/docs/models/gpt-5.4

Author: PeterDaveHello

pr_agent/algo/__init__.py

@@ -42,6 +42,8 @@
     'gpt-5.2-chat-latest': 128000,  # 128K, but may be limited by config.max_model_tokens
     'gpt-5.2-codex': 400000,  # 400K, but may be limited by config.max_model_tokens
     'gpt-5.3-codex': 400000,  # 400K, but may be limited by config.max_model_tokens
+    'gpt-5.4': 272000,  # 272K safe default without opt-in 1M context parameters
+    'gpt-5.4-2026-03-05': 272000,  # 272K safe default without opt-in 1M context parameters
     'o1-mini': 128000,  # 128K, but may be limited by config.max_model_tokens
     'o1-mini-2024-09-12': 128000,  # 128K, but may be limited by config.max_model_tokens
     'o1-preview': 128000,  # 128K, but may be limited by config.max_model_tokens

tests/unittest/test_get_max_tokens.py

@@ -22,6 +22,19 @@ def test_model_max_tokens(self, monkeypatch):
 
         assert get_max_tokens(model) == expected
 
+    @pytest.mark.parametrize("model", ["gpt-5.4", "gpt-5.4-2026-03-05"])
+    def test_gpt54_model_max_tokens(self, monkeypatch, model):
+        fake_settings = type('', (), {
+            'config': type('', (), {
+                'custom_model_max_tokens': 0,
+                'max_model_tokens': 0
+            })()
+        })()
+
+        monkeypatch.setattr(utils, "get_settings", lambda: fake_settings)
+
+        assert get_max_tokens(model) == 272000
+
     # Test situations where the model is not registered and exists as a custom model
     def test_model_has_custom(self, monkeypatch):
         fake_settings = type('', (), {

tests/unittest/test_litellm_reasoning_effort.py

@@ -307,7 +307,15 @@ async def test_gpt5_model_detection_various_versions(self, monkeypatch, mock_log
         fake_settings = create_mock_settings("medium")
         monkeypatch.setattr(litellm_handler, "get_settings", lambda: fake_settings)
 
-        gpt5_models = ["gpt-5-2025-08-07", "gpt-5.1", "gpt-5-turbo", "gpt-5.1-codex", "gpt-5.3-codex"]
+        gpt5_models = [
+            "gpt-5-2025-08-07",
+            "gpt-5.1",
+            "gpt-5.4",
+            "gpt-5.4-2026-03-05",
+            "gpt-5-turbo",
+            "gpt-5.1-codex",
+            "gpt-5.3-codex",
+        ]
 
         for model in gpt5_models:
             with patch('pr_agent.algo.ai_handlers.litellm_ai_handler.acompletion', new_callable=AsyncMock) as mock_completion: