chore: import upstream snapshot with attribution

tests/test_tools/test_sessions_send_errors.py

@@ -0,0 +1,59 @@
+from __future__ import annotations
+
+import json
+from types import SimpleNamespace
+
+import pytest
+
+from opensquilla.engine.types import ToolCall
+from opensquilla.tools.builtin import sessions as sessions_tools
+from opensquilla.tools.dispatch import build_tool_handler
+from opensquilla.tools.registry import ToolRegistry
+from opensquilla.tools.types import ToolSpec
+
+
+class _TerminalSessionManager:
+    async def get_session(self, session_key: str) -> object:
+        return SimpleNamespace(session_key=session_key, status="done")
+
+
+def _sessions_send_registry() -> ToolRegistry:
+    registry = ToolRegistry()
+    registry.register(
+        ToolSpec(
+            name="sessions_send",
+            description="send",
+            parameters={
+                "session_key": {"type": "string"},
+                "message": {"type": "string"},
+            },
+            required=["session_key", "message"],
+        ),
+        sessions_tools.sessions_send,
+    )
+    return registry
+
+
+@pytest.mark.asyncio
+async def test_sessions_send_terminal_session_error_is_user_actionable(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    monkeypatch.setattr(sessions_tools, "_session_manager", _TerminalSessionManager())
+
+    handler = build_tool_handler(_sessions_send_registry())
+    result = await handler(
+        ToolCall(
+            tool_use_id="tc-sessions-send-terminal",
+            tool_name="sessions_send",
+            arguments={
+                "session_key": "agent:main:subagent:done",
+                "message": "hello",
+            },
+        )
+    )
+
+    assert result.is_error is True
+    payload = json.loads(result.content)
+    assert payload["error_class"] == "SafeToolError"
+    assert "terminated" in payload["user_message"]
+    assert "internal error" not in payload["user_message"]