diff --git a/tests/tools/test_search_zero_match_and_multipath.py b/tests/tools/test_search_zero_match_and_multipath.py
index 9afccd982cbb..b2e7158b159a 100644
--- a/tests/tools/test_search_zero_match_and_multipath.py
+++ b/tests/tools/test_search_zero_match_and_multipath.py
@@ -53,6 +53,152 @@ def test_matching_search_unaffected(self, proj):
         assert "warning" not in r
 
 
+class TestZeroMatchProbeGrepFallback:
+    """Zero-match probes must still attach hints when rg is unavailable.
+
+    The main content search falls back to grep when ``rg`` is not on the
+    executed environment's PATH. The probe used to hard-require rg and
+    silently return no hint in that case — search worked (via grep) but
+    the zero-match steering was dead. These tests force the grep engine
+    and assert the same hints appear. Regression for the CI failure on
+    ``tests/tools/test_search_zero_match_and_multipath.py``.
+    """
+
+    @staticmethod
+    def _grep_ops(tmp_path):
+        from tools.environments.local import LocalEnvironment
+        from tools.file_operations import ShellFileOperations
+
+        d = tmp_path / "proj"
+        d.mkdir()
+        env = LocalEnvironment(cwd=str(d.parent))
+        ops = ShellFileOperations(env, cwd=str(d.parent))
+        # Simulate an environment with grep but no rg.
+        ops._has_command = lambda cmd: cmd == "grep"
+        return ops, d
+
+    def test_case_mismatch_hint_via_grep(self, tmp_path):
+        ops, d = self._grep_ops(tmp_path)
+        (d / "a.py").write_text("TOKEN_ALPHA = 'x'\n")
+        hint = ops._zero_match_probe("token_alpha", str(d), None)
+        assert hint and "case-insensitive" in hint
+
+    def test_literal_hint_via_grep(self, tmp_path):
+        ops, d = self._grep_ops(tmp_path)
+        (d / "meta.py").write_text("result = lookup[key+1]\n")
+        hint = ops._zero_match_probe("lookup[key+1]", str(d), None)
+        assert hint and "literal match" in hint
+
+    def test_hidden_only_hint_via_grep(self, tmp_path):
+        ops, d = self._grep_ops(tmp_path)
+        (d / ".secretdir").mkdir()
+        (d / ".secretdir" / "conf.cfg").write_text("HIDDEN_ONLY_TOKEN = true\n")
+        hint = ops._zero_match_probe("HIDDEN_ONLY_TOKEN", str(d), None)
+        assert hint and "hidden or gitignored" in hint
+
+    def test_true_zero_no_hint_via_grep(self, tmp_path):
+        ops, d = self._grep_ops(tmp_path)
+        (d / "a.py").write_text("x = 1\n")
+        assert ops._zero_match_probe("zzz_absent_zzz", str(d), None) is None
+
+    def test_probe_engine_prefers_rg_when_available(self, tmp_path):
+        from tools.environments.local import LocalEnvironment
+        from tools.file_operations import ShellFileOperations
+
+        d = tmp_path / "proj"
+        d.mkdir()
+        ops = ShellFileOperations(LocalEnvironment(cwd=str(d.parent)), cwd=str(d.parent))
+        ops._has_command = lambda cmd: cmd in ("rg", "grep")
+        engine, flags = ops._probe_engine()
+        assert engine == "rg"
+        assert "count-matches" in flags
+
+    def test_end_to_end_search_real_hint_via_forced_grep(self, tmp_path):
+        """End-to-end ``search()`` with grep forced attaches a real probe hint.
+
+        The whole pipeline — engine pick, ``_search_with_grep``, zero-count
+        detection, and the probe itself — runs for real (no sentinel, no
+        probe stub). Regression for the probe silently dying when rg is
+        absent while the main search itself falls back to grep.
+        """
+        ops, d = self._grep_ops(tmp_path)
+        (d / "a.py").write_text("TOKEN_ALPHA = 'x'\n")
+        r = ops.search("token_alpha", path=str(d), target="content")
+        assert r.total_count == 0
+        assert r.warning and "case-insensitive" in r.warning
+
+
+class TestNativePathBackendGating:
+    """rg native-path conversion is limited to the local Windows backend.
+
+    Commands run through ``self.env.execute``, so the executed backend —
+    not the host OS — decides whether the MSYS→native path rewrite
+    applies. A Windows host driving a remote backend (SSH, WSL, Docker,
+    ...) must never rewrite valid remote paths like ``/mnt/d/...`` into
+    ``D:\\...`` (issue #67914). These tests pin the split: conversion on
+    the local backend only, pass-through on remote backend paths.
+    """
+
+    @staticmethod
+    def _local_ops(tmp_path):
+        from tools.environments.local import LocalEnvironment
+        from tools.file_operations import ShellFileOperations
+
+        d = tmp_path / "proj"
+        d.mkdir()
+        return ShellFileOperations(LocalEnvironment(cwd=str(d.parent)), cwd=str(d.parent))
+
+    @staticmethod
+    def _remote_ops(commands=None):
+        from tools.file_operations import ShellFileOperations
+
+        class RemoteEnv:
+            """Minimal POSIX backend (SSH/WSL-like); no MSYS path rewriting."""
+
+            cwd = "/home/me"
+
+            def execute(self, command, cwd=None, **kwargs):
+                if commands is not None:
+                    commands.append(command)
+                return {"output": "", "returncode": 0}
+
+        return ShellFileOperations(RemoteEnv())
+
+    def test_local_windows_backend_converts_msys_path(self, tmp_path, monkeypatch):
+        import tools.environments.local as local_mod
+
+        ops = self._local_ops(tmp_path)
+        monkeypatch.setattr(local_mod, "_IS_WINDOWS", True)
+        out = ops._escape_native_arg("/c/Users/alice/notes.txt")
+        assert "C:" in out  # native drive form for the native rg.exe
+        assert "/c/Users" not in out
+
+    def test_remote_backend_keeps_remote_path_unchanged(self, monkeypatch):
+        import tools.environments.local as local_mod
+
+        ops = self._remote_ops()
+        # Simulate a Windows host driving a remote backend: conversion
+        # must still be skipped — the remote POSIX side owns these paths.
+        monkeypatch.setattr(local_mod, "_IS_WINDOWS", True)
+        assert ops._escape_native_arg("/mnt/d/data") == "'/mnt/d/data'"
+        assert ops._escape_native_arg("/mnt/c/Users/alice") == "'/mnt/c/Users/alice'"
+        assert ops._escape_native_arg("/home/user/proj") == "'/home/user/proj'"
+
+    def test_remote_backend_probe_command_keeps_remote_path(self, monkeypatch):
+        """The zero-match probe emits the raw remote path in its command."""
+        import tools.environments.local as local_mod
+
+        commands = []
+        ops = self._remote_ops(commands)
+        ops._has_command = lambda cmd: cmd == "rg"
+        monkeypatch.setattr(local_mod, "_IS_WINDOWS", True)  # Windows host, remote backend
+        assert ops._zero_match_probe("needle", "/mnt/d/data", None) is None
+        assert commands, "probe should have executed shell commands"
+        for cmd in commands:
+            assert "/mnt/d/data" in cmd
+            assert "D:" not in cmd
+
+
 class TestMultiPathRecovery:
     def test_two_existing_paths_merged(self, proj):
         p = f"{proj / 'proj'} {proj / 'extra'}"
diff --git a/tools/file_operations.py b/tools/file_operations.py
index f6a2deacaba8..c5605a3ddd5c 100644
--- a/tools/file_operations.py
+++ b/tools/file_operations.py
@@ -1001,6 +1001,52 @@ def _escape_shell_arg(self, arg: str) -> str:
         # Use single quotes and escape any single quotes in the string
         return "'" + arg.replace("'", "'\"'\"'") + "'"
 
+    def _escape_native_arg(self, arg: str) -> str:
+        """Escape *arg* for a native Windows binary (no MSYS path form).
+
+        ``_escape_shell_arg`` rewrites drive paths to the Git Bash
+        ``/c/Users/x`` form. That is correct for MSYS-aware tools (bash
+        builtins, grep from Git Bash), but native Windows executables such
+        as the WinGet ``rg.exe`` cannot read ``/c/...`` when MSYS argument
+        conversion is disabled (``MSYS2_ARG_CONV_EXCL=*``, which the Hermes
+        local env sets deliberately to stop flag mangling). Native tools
+        need the ``C:/Users/x`` form.
+
+        The rewrite is limited to the local Windows backend (see
+        :meth:`_local_windows_backend`): commands execute through
+        ``self.env.execute`` on whatever backend is wired in, so the host
+        OS alone must never trigger it. A Windows host driving a remote
+        SSH/WSL/Docker backend would otherwise rewrite valid remote paths
+        such as ``/mnt/d/...`` into ``D:\\...`` and break the remote
+        search (issue #67914). Remote paths pass through unchanged.
+        """
+        from tools.environments.local import _msys_to_windows_path
+
+        native = _msys_to_windows_path(arg) if self._local_windows_backend() else arg
+        return "'" + native.replace("'", "'\"'\"'") + "'"
+
+    def _local_windows_backend(self) -> bool:
+        """Return True iff commands execute on the local Git Bash on a Windows host.
+
+        This gates on the executed *backend*, not the host OS: every
+        backend (local, SSH, WSL, Docker, Modal, ...) runs commands
+        through ``self.env.execute``, and only the local environment on a
+        Windows host speaks Git Bash with MSYS argument conversion
+        disabled and a native ``rg.exe`` — the one place the MSYS→native
+        path rewrite in :meth:`_escape_native_arg` is valid. Mirrors the
+        ``_lsp_local_only`` gate used for the LSP path.
+        """
+        env = getattr(self, "env", None)
+        if env is None:
+            # Defensive: some tests construct ShellFileOperations via
+            # ``__new__`` without going through ``__init__``.
+            return False
+        try:
+            from tools.environments.local import LocalEnvironment, _IS_WINDOWS
+        except Exception:  # noqa: BLE001
+            return False
+        return isinstance(env, LocalEnvironment) and _IS_WINDOWS
+
     def _atomic_write(self, path: str, content: str) -> "ExecuteResult":
         """Write ``content`` to ``path`` atomically via temp-file + rename.
 
@@ -2272,15 +2318,27 @@ def _zero_match_probe(self, pattern: str, path: str,
         13.9% of production content searches return zero matches and give
         the model nothing to steer by. Run ONE cheap case-insensitive count
         probe; if it hits, say so. If the pattern contains regex
-        metacharacters, also probe it as a fixed string. Bounded: two rg
+        metacharacters, also probe it as a fixed string. Bounded: two
         invocations max, count-only output.
+
+        Uses whatever engine the main search would have used — rg when
+        available, grep otherwise — so the probe never silently dies in
+        an environment where the main search itself fell back to grep
+        (e.g. a test/sandbox PATH without rg on it).
         """
-        if not self._has_command('rg'):
+        engine, count_flags = self._probe_engine()
+        if engine is None:
             return None
-        glob_expr = f" --glob {self._escape_shell_arg(file_glob)}" if file_glob else ""
+        glob_expr = ""
+        if file_glob:
+            glob_flag = "--glob" if engine == "rg" else "--include"
+            glob_expr = f" {glob_flag} {self._escape_shell_arg(file_glob)}"
+        # Native rg.exe cannot read the MSYS /c/... form when MSYS arg
+        # conversion is disabled; grep (an MSYS tool) needs that form.
+        path_arg = self._escape_native_arg(path) if engine == "rg" else self._escape_shell_arg(path)
         probe = self._exec(
-            f"rg -i --count-matches{glob_expr} "
-            f"{self._escape_shell_arg(pattern)} {self._escape_shell_arg(path)} "
+            f"{engine} {count_flags}{glob_expr} "
+            f"{self._escape_shell_arg(pattern)} {path_arg} "
             f"2>/dev/null | head -50",
             timeout=30,
         )
@@ -2299,10 +2357,12 @@ def _zero_match_probe(self, pattern: str, path: str,
         # Hidden/ignored probe: rg skips dotdirs and .gitignore'd files by
         # default. When the pattern exists only there, say so instead of
         # returning a bare zero (bench case: match in .hidden/ silently
-        # missing from results).
+        # missing from results). Under grep, the case probe carries
+        # --exclude-dir='.*' (mirroring the main search); this probe
+        # drops that exclusion so dot-directory matches are found.
         hidden = self._exec(
-            f"rg --hidden --no-ignore --count-matches{glob_expr} "
-            f"{self._escape_shell_arg(pattern)} {self._escape_shell_arg(path)} "
+            f"{engine} {self._probe_hidden_flags(engine)}{glob_expr} "
+            f"{self._escape_shell_arg(pattern)} {path_arg} "
             f"2>/dev/null | head -50",
             timeout=30,
         )
@@ -2321,8 +2381,8 @@ def _zero_match_probe(self, pattern: str, path: str,
             )
         if re.search(r"[.\[\](){}?*+^$\\|]", pattern):
             fixed = self._exec(
-                f"rg -F --count-matches{glob_expr} "
-                f"{self._escape_shell_arg(pattern)} {self._escape_shell_arg(path)} "
+                f"{engine} -F {count_flags}{glob_expr} "
+                f"{self._escape_shell_arg(pattern)} {path_arg} "
                 f"2>/dev/null | head -50",
                 timeout=30,
             )
@@ -2339,6 +2399,39 @@ def _zero_match_probe(self, pattern: str, path: str,
                 )
         return None
 
+    def _probe_engine(self) -> "tuple[str | None, str]":
+        """Pick the search engine for zero-match probes.
+
+        Returns (engine, count_flags): ``rg`` with ``-i --count-matches``
+        when ripgrep is available; ``grep`` with ``-rniHc`` otherwise;
+        ``(None, "")`` when neither exists. Mirrors the main search's
+        engine precedence so the probe behaves identically to the search
+        that produced the zero.
+        """
+        if self._has_command('rg'):
+            return "rg", "-i --count-matches"
+        if self._has_command('grep'):
+            # -c emits per-file counts (path:count), which the probe
+            # parser expects; -H forces the filename even for a
+            # single-file search. --exclude-dir mirrors the main grep
+            # search (and rg's default) so hidden files are probed by
+            # the dedicated hidden probe, not the case probe.
+            return "grep", "-rniHc --exclude-dir='.*'"
+        return None, ""
+
+    def _probe_hidden_flags(self, engine: str) -> str:
+        """Flags for the hidden/ignored probe, per engine.
+
+        rg: ``--hidden --no-ignore --count-matches`` overrides the
+        default dotdir and .gitignore exclusion. grep: the case probe
+        carries ``--exclude-dir='.*'`` (mirroring the main search), so
+        the hidden probe must drop that exclusion — ``-rniHc`` with no
+        exclude descends into dot-directories and finds the matches.
+        """
+        if engine == "rg":
+            return "--hidden --no-ignore --count-matches"
+        return "-rniHc"
+
     def _search_files(self, pattern: str, path: str, limit: int, offset: int) -> SearchResult:
         """Search for files by name pattern (glob-like)."""
         # Auto-prepend **/ for recursive search if not already present
@@ -2442,9 +2535,11 @@ def _search_files_rg(self, pattern: str, path: str, limit: int, offset: int) ->
 
         fetch_limit = limit + offset
         # Try mtime-sorted first (rg 13+); fall back to unsorted if not supported.
+        # rg.exe is a native binary — pass the native drive form on Windows.
+        native_root = self._escape_native_arg(path)
         cmd_sorted = (
             f"rg --files --sortr=modified -g {self._escape_shell_arg(glob_pattern)} "
-            f"{self._escape_shell_arg(path)} 2>/dev/null "
+            f"{native_root} 2>/dev/null "
             f"| head -n {fetch_limit}"
         )
         result = self._exec(cmd_sorted, timeout=60)
@@ -2455,7 +2550,7 @@ def _search_files_rg(self, pattern: str, path: str, limit: int, offset: int) ->
             # --sortr may have failed on older rg; retry without it.
             cmd_plain = (
                 f"rg --files -g {self._escape_shell_arg(glob_pattern)} "
-                f"{self._escape_shell_arg(path)} 2>/dev/null "
+                f"{native_root} 2>/dev/null "
                 f"| head -n {fetch_limit}"
             )
             result = self._exec(cmd_plain, timeout=60)
@@ -2539,7 +2634,10 @@ def _search_with_rg(self, pattern: str, path: str, file_glob: Optional[str],
         
         # Add pattern and path
         cmd_parts.append(self._escape_shell_arg(pattern))
-        cmd_parts.append(self._escape_shell_arg(path))
+        # rg.exe on Windows is a native binary: it cannot read the MSYS
+        # /c/... form when MSYS argument conversion is disabled, so pass
+        # the native drive form (C:/...) for the search root.
+        cmd_parts.append(self._escape_native_arg(path))
         
         # Fetch extra rows so we can report the true total before slicing.
         # For context mode, rg emits separator lines ("--") between groups,