fix(cli): enable arrow-key history and line editing in adk run

src/google/adk/cli/cli.py

@@ -193,6 +193,19 @@ def _collect_pending_function_calls(
   return pending
 
 
+def _enable_line_editing() -> None:
+  """Enables arrow-key editing and history for input() when available.
+
+  input() only supports line editing once the readline module is imported.
+  readline is not available on Windows, where the console already provides
+  history.
+  """
+  try:
+    import readline  # noqa: F401
+  except ImportError:
+    pass
+
+
 def _is_positive_response(s: str) -> bool:
   """Returns True if the string is a positive response."""
   return s.strip().lower() in ('y', 'yes', 'true', 'confirm')
@@ -267,6 +280,7 @@ async def run_interactively(
     agent_loader: Optional[AgentLoader] = None,
     agent_folder_name: Optional[str] = None,
 ) -> None:
+  _enable_line_editing()
   app = _to_app(root_agent_or_app, session.app_name)
   runner = Runner(
       app=app,

tests/unittests/cli/utils/test_cli.py

@@ -644,6 +644,53 @@ async def test_run_interactively_whitespace_and_exit(
   assert any("echo:hello" in m for m in echoed)
 
 
+def test_enable_line_editing_imports_readline(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+  """_enable_line_editing should import readline so input() gets history."""
+  pytest.importorskip("readline")
+  monkeypatch.delitem(sys.modules, "readline", raising=False)
+
+  cli._enable_line_editing()
+
+  assert "readline" in sys.modules
+
+
+def test_enable_line_editing_without_readline(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+  """_enable_line_editing should not fail where readline is missing."""
+  # A None entry in sys.modules makes the import raise ImportError, as on
+  # Windows.
+  monkeypatch.setitem(sys.modules, "readline", None)
+
+  cli._enable_line_editing()
+
+
+@pytest.mark.asyncio
+async def test_run_interactively_enables_line_editing(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+  """run_interactively should enable line editing before reading input."""
+  session_service = InMemorySessionService()
+  sess = await session_service.create_session(app_name="dummy", user_id="u")
+  calls: list[str] = []
+  monkeypatch.setattr(
+      cli, "_enable_line_editing", lambda: calls.append("enabled")
+  )
+  monkeypatch.setattr("builtins.input", lambda *_a, **_k: "exit")
+
+  await cli.run_interactively(
+      BaseAgent(name="root"),
+      InMemoryArtifactService(),
+      sess,
+      session_service,
+      InMemoryCredentialService(),
+  )
+
+  assert calls == ["enabled"]
+
+
 def test_print_event_omits_internal_metadata_in_jsonl(
     monkeypatch: pytest.MonkeyPatch,
 ) -> None: