Python: Fix persistent PowerShell sessions dropping table-formatted output

python/packages/tools/agent_framework_tools/shell/_session.py

@@ -360,7 +360,12 @@ def _build_script(self, command: str, sentinel: str) -> str:
                 " $__af_last = $LASTEXITCODE;"
                 " try {"
                 f"   $__af_cmd = [System.Text.Encoding]::UTF8.GetString([Convert]::FromBase64String('{encoded}'));"
-                "   Invoke-Expression $__af_cmd;"
+                # Format the output inside the try. Left to the host, pwsh
+                # formats a script block's output only after the block has
+                # returned, so the sentinel written in finally would overtake
+                # anything rendered as a table or list (Get-Location,
+                # Select-Object, custom objects) and that output would be lost.
+                "   Invoke-Expression $__af_cmd | Out-Default;"
                 # $? has to be read on the very next statement: anything else
                 # in between overwrites it.
                 "   $__af_ok = $?;"

python/packages/tools/tests/test_local_shell_tool.py

@@ -3,6 +3,7 @@
 import asyncio
 import json
 import os
+import shutil
 import sys
 from collections.abc import Awaitable, Mapping, Sequence
 from typing import Any
@@ -24,6 +25,7 @@
 _TEST_SHELL = "agent-framework-test-shell"
 _APPROVED_COMMAND = "printf '%s' approved-value"
 _ALTERNATE_COMMAND = "printf '%s' alternate-value"
+_POWERSHELL = shutil.which("pwsh") or (shutil.which("powershell") if sys.platform == "win32" else None)
 
 
 class _FakeExecProcess:
@@ -356,6 +358,33 @@ async def test_persistent_powershell_utf8_roundtrip() -> None:
         assert "café" in result.stdout
 
 
+@pytest.mark.skipif(_POWERSHELL is None, reason="PowerShell is not installed")
+async def test_persistent_powershell_returns_formatted_object_output(tmp_path: os.PathLike[str]) -> None:
+    """Output that pwsh renders as a table must arrive before the sentinel.
+
+    The host formats a script block's output only after the block returns,
+    which is after the sentinel has been written, so this output used to be
+    dropped, along with any plain string written after the first object.
+    Runs wherever PowerShell is installed, not just on Windows.
+    """
+    assert _POWERSHELL is not None
+    async with LocalShellTool(
+        mode="persistent",
+        shell=[_POWERSHELL, "-NoLogo", "-NoProfile", "-NonInteractive", "-Command", "-"],
+        approval_mode="never_require",
+        acknowledge_unsafe=True,
+        workdir=str(tmp_path),
+    ) as tool:
+        result = await tool.run("[pscustomobject]@{ Marker = 'af-object' }; Write-Output 'af-trailing'")
+        assert result.exit_code == 0
+        assert "af-object" in result.stdout
+        assert "af-trailing" in result.stdout
+
+        selected = await tool.run(f"Get-Item -LiteralPath '{tmp_path}' | Select-Object Name")
+        assert selected.exit_code == 0
+        assert os.path.basename(str(tmp_path)) in selected.stdout
+
+
 async def test_concurrent_first_calls_do_not_spawn_two_sessions() -> None:
     """Regression: startup must be serialised so two concurrent first callers
     don't each spawn their own subprocess."""