fix(win): add Windows platform hint in bash tool description

agent/tools/bash/bash.py

@@ -23,7 +23,7 @@ class Bash(BaseTool):
     name: str = "bash"
     description: str = f"""Execute a bash command in the current working directory. Returns stdout and stderr. Output is truncated to last {DEFAULT_MAX_LINES} lines or {DEFAULT_MAX_BYTES // 1024}KB (whichever is hit first). If truncated, full output is saved to a temp file.
 {'''
-PLATFORM: Windows (PowerShell).
+PLATFORM: Windows (cmd.exe). Do NOT use Unix-only commands like grep, head, tail, sed, awk.
 ''' if _IS_WIN else ''}
 ENVIRONMENT: All API keys from env_config are auto-injected. Use $VAR_NAME directly.
 
@@ -106,25 +106,13 @@ SAFETY:
             else:
                 logger.debug(f"[Bash] Process User: {os.environ.get('USERNAME', os.environ.get('USER', 'unknown'))}")
             
+            # On Windows, convert $VAR references to %VAR% for cmd.exe
             if self._IS_WIN:
                 env["PYTHONIOENCODING"] = "utf-8"
-                wrapped = (
+                command = self._convert_env_vars_for_windows(command, dotenv_vars)
-                    "[Console]::OutputEncoding = [System.Text.Encoding]::UTF8; "
+                if command and not command.strip().lower().startswith("chcp"):
-                    f"{command}; exit $LASTEXITCODE"
+                    command = f"chcp 65001 >nul 2>&1 && {command}"
-                )
+
-                result = subprocess.run(
-                    ["powershell.exe", "-NoProfile", "-NonInteractive",
-                     "-ExecutionPolicy", "Bypass", "-Command", wrapped],
-                    cwd=self.cwd,
-                    stdout=subprocess.PIPE,
-                    stderr=subprocess.PIPE,
-                    text=True,
-                    encoding="utf-8",
-                    errors="replace",
-                    timeout=timeout,
-                    env=env,
-                )
-            else:
             result = subprocess.run(
                 command,
                 shell=True,