fix(tools): allow Unicode letters in workdir validation

The workdir allowlist regex was ASCII-only, so perfectly normal
non-ASCII workdirs (Chinese Obsidian vault paths, accented dirnames)
were rejected with 'disallowed character'. Replace the regex with a
per-character check that accepts Unicode letters/digits (str.isalnum)
plus the same safe ASCII punctuation set, while still rejecting shell
metacharacters, control characters (newlines/tabs), and NUL.

Salvaged from PR #54314.

Co-authored-by: kshitij <82637225+kshitijk4poor@users.noreply.github.com>

tests/tools/test_terminal_tool.py

@@ -83,6 +83,26 @@ def test_validate_workdir_blocks_shell_metacharacters_in_windows_paths():
     assert terminal_tool._validate_workdir("C:\\Users\\Alice\\project\nwhoami")
 
 
+def test_validate_workdir_allows_unicode_filesystem_paths():
+    assert terminal_tool._validate_workdir(
+        "/Users/alice/Documents/Obs_Hermes_Data/项目-projects/客户拜访"
+    ) is None
+    assert terminal_tool._validate_workdir("/tmp/テスト") is None
+    assert terminal_tool._validate_workdir("/home/jürgen/über projekt") is None
+
+
+def test_validate_workdir_still_blocks_metachars_in_unicode_paths():
+    # Widening to Unicode letters must not open the injection boundary:
+    # shell metacharacters and control chars stay rejected even when mixed
+    # with non-ASCII path segments.
+    assert terminal_tool._validate_workdir("/tmp/テスト; rm -rf /")
+    assert terminal_tool._validate_workdir("/tmp/项目$(whoami)")
+    assert terminal_tool._validate_workdir("/tmp/über`id`")
+    assert terminal_tool._validate_workdir("/tmp/テスト\nwhoami")
+    assert terminal_tool._validate_workdir("/tmp/项目|cat /etc/passwd")
+    assert terminal_tool._validate_workdir("/tmp/ü\x00ber")
+
+
 def test_count_real_sudo_invocations_ignores_mentions(monkeypatch):
     assert terminal_tool._count_real_sudo_invocations("grep sudo README.md") == 0
     assert terminal_tool._count_real_sudo_invocations("sudo a; sudo b") == 2

tools/terminal_tool.py

@@ -374,10 +374,24 @@ def _check_all_guards(command: str, env_type: str,
 
 
 # Allowlist: characters that can legitimately appear in directory paths.
-# Covers alphanumeric, path separators, Windows drive/UNC separators, tilde,
-# dot, hyphen, underscore, space, plus, at, equals, and comma.  Everything
-# else is rejected.
-_WORKDIR_SAFE_RE = re.compile(r'^[A-Za-z0-9/\\:_\-.~ +@=,]+$')
+# Covers Unicode letters/digits, path separators, Windows drive/UNC separators,
+# tilde, dot, hyphen, underscore, space, plus, at, equals, and comma.  Shell
+# metacharacters remain rejected.  This intentionally fixes the old ASCII-only
+# guard that blocked perfectly normal workdirs such as Chinese Obsidian vault
+# paths while preserving the injection boundary around command execution
+# (the cwd is additionally shlex-quoted before it reaches the shell; this
+# allowlist is defense-in-depth).
+_WORKDIR_SAFE_ASCII_CHARS = frozenset('/\\:_-.~ +@=,')
+
+
+def _is_safe_workdir_char(ch: str) -> bool:
+    if not ch:
+        return False
+    # Reject control characters (including newlines/tabs) and NUL bytes before
+    # considering Unicode categories.
+    if ord(ch) < 32 or ord(ch) == 127:
+        return False
+    return ch.isalnum() or ch in _WORKDIR_SAFE_ASCII_CHARS
 
 
 def _validate_workdir(workdir: str) -> str | None:
@@ -390,15 +404,12 @@ def _validate_workdir(workdir: str) -> str | None:
     """
     if not workdir:
         return None
-    if not _WORKDIR_SAFE_RE.match(workdir):
-        # Find the first offending character for a helpful message.
-        for ch in workdir:
-            if not _WORKDIR_SAFE_RE.match(ch):
-                return (
-                    f"Blocked: workdir contains disallowed character {repr(ch)}. "
-                    "Use a simple filesystem path without shell metacharacters."
-                )
-        return "Blocked: workdir contains disallowed characters."
+    for ch in workdir:
+        if not _is_safe_workdir_char(ch):
+            return (
+                f"Blocked: workdir contains disallowed character {repr(ch)}. "
+                "Use a simple filesystem path without shell metacharacters."
+            )
     return None