fix(python): address review nits for loop runner, step timeout, and trailing newline

clients/python/src/ate_env/backend/__init__.py

@@ -17,4 +17,3 @@
 from .substrate import SubstrateBackendDriver
 
 __all__ = ["BackendDriver", "MockBackendDriver", "SubstrateBackendDriver"]
-

clients/python/src/ate_env/fleet.py

@@ -233,6 +233,7 @@ def _acquire_one(
             backend=self.backend,
             runtime=runtime,
             data_plane=data_plane,
+            default_timeout_s=self.config.step_timeout_s,
         )
 
     def _build_runtime(

clients/python/src/ate_env/handle.py

@@ -40,13 +40,14 @@ class SandboxHandle:
     backend: BackendDriver = field(repr=False)
     runtime: RuntimeGuestHook = field(repr=False)
     data_plane: DataPlaneEndpoint | None = None
+    default_timeout_s: float = 120.0
 
     def exec(
         self,
         command: str | list[str],
         cwd: str = "",
         env: dict[str, str] | None = None,
-        timeout_s: float = 120.0,
+        timeout_s: float | None = None,
         check: bool = True,
     ) -> ExecResult:
         """Execute command inside the sandbox.
@@ -57,10 +58,11 @@ def exec(
         of ``check``.
         Returns ExecResult.
         """
-        res = self.runtime.exec(command, cwd=cwd, env=env, timeout_s=timeout_s)
+        to_s = self.default_timeout_s if timeout_s is None else timeout_s
+        res = self.runtime.exec(command, cwd=cwd, env=env, timeout_s=to_s)
         if check and res.timed_out:
             raise CommandTimeoutError(
-                f"Command '{command}' timed out after {timeout_s:g}s:\n"
+                f"Command '{command}' timed out after {to_s:g}s:\n"
                 f"STDOUT: {res.stdout}\nSTDERR: {res.stderr}",
                 result=res,
             )
@@ -77,14 +79,15 @@ async def exec_async(
         command: str | list[str],
         cwd: str = "",
         env: dict[str, str] | None = None,
-        timeout_s: float = 120.0,
+        timeout_s: float | None = None,
         check: bool = True,
     ) -> ExecResult:
         """Asynchronously execute command inside the sandbox."""
-        res = await self.runtime.exec_async(command, cwd=cwd, env=env, timeout_s=timeout_s)
+        to_s = self.default_timeout_s if timeout_s is None else timeout_s
+        res = await self.runtime.exec_async(command, cwd=cwd, env=env, timeout_s=to_s)
         if check and res.timed_out:
             raise CommandTimeoutError(
-                f"Command '{command}' timed out after {timeout_s:g}s:\n"
+                f"Command '{command}' timed out after {to_s:g}s:\n"
                 f"STDOUT: {res.stdout}\nSTDERR: {res.stderr}",
                 result=res,
             )

clients/python/src/ate_env/loop_runner.py

@@ -73,7 +73,7 @@ async def _shutdown() -> None:
                 pass
             self._loop.call_soon_threadsafe(self._loop.stop)
             self._thread.join(timeout=2.0)
-            if not self._loop.is_closed():
+            if not self._thread.is_alive() and not self._loop.is_closed():
                 self._loop.close()
 
     def __del__(self) -> None:

clients/python/tests/test_exec_semantics.py

@@ -118,3 +118,10 @@ def test_mock_runtime_file_round_trip(name):
 def test_read_missing_file_raises_file_not_found():
     with pytest.raises(FileNotFoundError):
         MockRuntimeHook().read_file_bytes("/missing.txt")
+
+
+def test_fleet_step_timeout_applies_to_handle():
+    fleet = SandboxFleet(FleetConfig(backend="mock", step_timeout_s=42.0))
+    h = fleet.acquire("t1")
+    assert h.default_timeout_s == 42.0
+    h.release()