fix: preserve ADK behavior on Windows

Several paths misbehaved when ADK was imported or run on Windows: drive-letter paths were split at the wrong colon (including for paths that did not exist yet), text writes could rewrite explicit newlines, telemetry detection assumed POSIX separators, and the Bash tool imported the POSIX-only resource module at import time. This splits eval selectors from the right while preserving drive paths, writes text with exact newline handling, normalizes telemetry paths before matching, and imports the Bash tool safely on Windows with an explicit POSIX-only error after confirmation.

Co-authored-by: George Weale <gweale@google.com>
PiperOrigin-RevId: 952417974

Author: GWeale

src/google/adk/environment/_local_environment.py

@@ -162,6 +162,8 @@ def _sync_read(path: Path) -> bytes:
   def _sync_write(path: Path, content: str | bytes) -> None:
     os.makedirs(path.parent, exist_ok=True)
     mode = 'w' if isinstance(content, str) else 'wb'
-    kwargs = {'encoding': 'utf-8'} if isinstance(content, str) else {}
+    kwargs = (
+        {'encoding': 'utf-8', 'newline': ''} if isinstance(content, str) else {}
+    )
     with open(path, mode, **kwargs) as f:
       f.write(content)

src/google/adk/telemetry/tracing.py

@@ -652,7 +652,7 @@ def _instrumented_with_opentelemetry_instrumentation_google_genai() -> bool:
   while wrapped := getattr(maybe_wrapped_function, "__wrapped__", None):
     if (
         "opentelemetry/instrumentation/google_genai"
-        in maybe_wrapped_function.__code__.co_filename
+        in maybe_wrapped_function.__code__.co_filename.replace("\\", "/")
     ):
       return True
     maybe_wrapped_function = wrapped  # pyright: ignore[reportAny]

src/google/adk/tools/bash_tool.py

@@ -18,10 +18,10 @@
 
 import asyncio
 import dataclasses
+import importlib
 import logging
 import os
 import pathlib
-import resource
 import shlex
 import signal
 from typing import Any
@@ -34,6 +34,8 @@
 
 logger = logging.getLogger("google_adk." + __name__)
 
+_resource = importlib.import_module("resource") if os.name == "posix" else None
+
 
 @dataclasses.dataclass(frozen=True)
 class BashToolPolicy:
@@ -77,21 +79,23 @@ def _validate_command(command: str, policy: BashToolPolicy) -> Optional[str]:
 
 def _set_resource_limits(policy: BashToolPolicy) -> None:
   """Sets resource limits for the subprocess based on the provided policy."""
+  if _resource is None:
+    return
   try:
-    resource.setrlimit(resource.RLIMIT_CORE, (0, 0))
+    _resource.setrlimit(_resource.RLIMIT_CORE, (0, 0))
     if policy.max_memory_bytes:
-      resource.setrlimit(
-          resource.RLIMIT_AS,
+      _resource.setrlimit(
+          _resource.RLIMIT_AS,
           (policy.max_memory_bytes, policy.max_memory_bytes),
       )
     if policy.max_file_size_bytes:
-      resource.setrlimit(
-          resource.RLIMIT_FSIZE,
+      _resource.setrlimit(
+          _resource.RLIMIT_FSIZE,
           (policy.max_file_size_bytes, policy.max_file_size_bytes),
       )
     if policy.max_child_processes:
-      resource.setrlimit(
-          resource.RLIMIT_NPROC,
+      _resource.setrlimit(
+          _resource.RLIMIT_NPROC,
           (policy.max_child_processes, policy.max_child_processes),
       )
   except (ValueError, OSError) as e:
@@ -171,6 +175,9 @@ async def run_async(
     elif not tool_context.tool_confirmation.confirmed:
       return {"error": "This tool call is rejected."}
 
+    if os.name != "posix":
+      return {"error": "ExecuteBashTool is only supported on POSIX systems."}
+
     stdout = None
     stderr = None
     try:

tests/unittests/cli/utils/test_cli_eval.py

@@ -148,3 +148,30 @@ async def test_get_root_agent_raises_without_supported_entrypoint(monkeypatch):
   )
   with pytest.raises(ValueError, match="root_agent|get_agent_async"):
     await get_root_agent("some/dir")
+
+
+def test_parse_evals_preserves_windows_drive_in_file_path(tmp_path):
+  from google.adk.cli.cli_eval import parse_and_get_evals_to_run
+
+  eval_set_file = tmp_path / "evals.json"
+  eval_set_file.write_text("{}", encoding="utf-8")
+
+  assert parse_and_get_evals_to_run([str(eval_set_file)]) == {
+      str(eval_set_file): []
+  }
+
+
+def test_parse_evals_preserves_missing_windows_drive_path():
+  from google.adk.cli.cli_eval import parse_and_get_evals_to_run
+
+  eval_set_file = r"C:\missing\evals.json"
+
+  assert parse_and_get_evals_to_run([eval_set_file]) == {eval_set_file: []}
+
+
+def test_parse_evals_splits_case_selector_from_right():
+  from google.adk.cli.cli_eval import parse_and_get_evals_to_run
+
+  assert parse_and_get_evals_to_run([r"C:\evals\set.json:case1,case2"]) == {
+      r"C:\evals\set.json": ["case1", "case2"]
+  }

tests/unittests/telemetry/test_functional.py

@@ -175,6 +175,26 @@ def test_instrumented_with_opentelemetry_instrumentation_google_genai():
   )
 
 
+def test_instrumented_detection_normalizes_windows_path_separators(
+    monkeypatch: pytest.MonkeyPatch,
+):
+  """Backslash-separated instrumentation paths are matched on Windows."""
+  windows_path = r"C:\pkg\opentelemetry\instrumentation\google_genai\patch.py"
+
+  class _FakeCode:
+    co_filename = windows_path
+
+  class _FakeInstrumentedFunction:
+    __code__ = _FakeCode
+    __wrapped__ = object()
+
+  monkeypatch.setattr(
+      tracing.Models, "generate_content", _FakeInstrumentedFunction
+  )
+
+  assert tracing._instrumented_with_opentelemetry_instrumentation_google_genai()
+
+
 # ---------------------------------------------------------------------------
 # MCP integration: telemetry adds zero ``list_tools()`` calls of its own.
 #

tests/unittests/tools/test_bash_tool_windows.py

@@ -0,0 +1,43 @@
+# Copyright 2026 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import annotations
+
+from unittest import mock
+
+from google.adk.tools import bash_tool
+from google.adk.tools.tool_confirmation import ToolConfirmation
+from google.adk.tools.tool_context import ToolContext
+import pytest
+
+
+@pytest.mark.asyncio
+async def test_execute_bash_tool_reports_unsupported_platform(
+    tmp_path, monkeypatch: pytest.MonkeyPatch
+):
+  """A confirmed Bash command returns a clear error on non-POSIX hosts."""
+  tool = bash_tool.ExecuteBashTool(workspace=tmp_path)
+  tool_context = mock.create_autospec(ToolContext, instance=True)
+  confirmation = mock.create_autospec(ToolConfirmation, instance=True)
+  confirmation.confirmed = True
+  tool_context.tool_confirmation = confirmation
+  monkeypatch.setattr(bash_tool.os, "name", "nt")
+
+  result = await tool.run_async(
+      args={"command": "echo hello"}, tool_context=tool_context
+  )
+
+  assert result == {
+      "error": "ExecuteBashTool is only supported on POSIX systems."
+  }

tests/unittests/tools/test_local_environment.py

@@ -69,6 +69,15 @@ async def test_write_bytes_content(self, env: LocalEnvironment):
     data = await env.read_file("binary.bin")
     assert data == raw
 
+  @pytest.mark.asyncio
+  async def test_write_preserves_explicit_crlf(self, env: LocalEnvironment):
+    """Explicit CRLF sequences are written without newline translation."""
+    await env.write_file("crlf.txt", "first\r\nsecond\r\n")
+
+    data = await env.read_file("crlf.txt")
+
+    assert data == b"first\r\nsecond\r\n"
+
   @pytest.mark.asyncio
   async def test_write_creates_parent_dirs(self, env: LocalEnvironment):
     """Parent directories are created automatically."""