fix + add general env key

harness.py

@@ -19,9 +19,21 @@ if TYPE_CHECKING:
     )
 DEFAULT_PROMPT_PATH = Path("prompt.md")
 DEFAULT_SESSION_PATH = Path("session/default.jsonl")
-MODEL_ENV_NAMES = ("CEREBRAS_MODEL_STRING", "GROQ_MODEL_STRING")
-BASE_URL_ENV_NAMES = ("CEREBRAS_BASE_URL", "GROQ_BASE_URL")
-API_KEY_ENV_NAMES = ("CEREBRAS_API_KEY", "GROQ_API_KEY")
+MODEL_ENV_NAMES = (
+    "MODEL_NAME",
+    "GROQ_MODEL_STRING",
+    "CEREBRAS_MODEL_STRING",
+)
+BASE_URL_ENV_NAMES = (
+    "MODEL_BASE_URL",
+    "GROQ_BASE_URL",
+    "CEREBRAS_BASE_URL",
+)
+API_KEY_ENV_NAMES = (
+    "MODEL_API_KEY",
+    "GROQ_API_KEY",
+    "CEREBRAS_API_KEY",
+)
 
 
 def utc_now_iso() -> str:
@@ -187,7 +199,7 @@ def messages_from_session(
                 }
             )
 
-    return cast(list[ChatCompletionMessageParam], messages)
+    return cast("list[ChatCompletionMessageParam]", messages)
 
 
 def tool_result_content(payload: dict[str, Any]) -> str: