fix(providers): validate stream idle timeout config

nanobot/providers/openai_compat_provider.py

@@ -25,6 +25,7 @@ from nanobot.providers.base import (
     LLMResponse,
     ToolCallRequest,
     parse_tool_arguments,
+    resolve_stream_idle_timeout_s,
     tool_arguments_json_for_replay,
 )
 from nanobot.providers.openai_responses import (
@@ -1386,7 +1387,7 @@ class OpenAICompatProvider(LLMProvider):
         on_tool_call_delta: Callable[[dict[str, Any]], Awaitable[None]] | None = None,
     ) -> LLMResponse:
         await self._ensure_client()
-        idle_timeout_s = int(os.environ.get("NANOBOT_STREAM_IDLE_TIMEOUT_S", "90"))
+        idle_timeout_s = resolve_stream_idle_timeout_s()
         try:
             if self._should_use_responses_api(model, reasoning_effort):
                 try:
@@ -1503,7 +1504,7 @@ class OpenAICompatProvider(LLMProvider):
             return LLMResponse(
                 content=(
                     f"Error calling LLM: stream stalled for more than "
-                    f"{idle_timeout_s} seconds"
+                    f"{idle_timeout_s:g} seconds"
                 ),
                 finish_reason="error",
                 error_kind="timeout",