fix(auth): return the user-local external CLI as one native path on Windows

The user-local known dir is spelled %USERPROFILE%/.local/bin, so a Windows hit came back
with mixed separators in provider status and in the spawned ACP argv. Normalize the
resolved path.

Co-authored-by: Finn763 <165816600+finn763@users.noreply.github.com>

hermes_cli/auth_external_process.py

@@ -24,7 +24,9 @@ def resolve_external_process_command(command: str) -> Optional[str]:
         lookup = os.path.abspath(os.path.expandvars(os.path.expanduser(command)))
     found = locate_command(lookup, known_dirs=user_local_bin()).command
     if found:
-        return found[0]
+        # Known dirs are written with "/" (%USERPROFILE%/.local/bin); normalize so a Windows hit
+        # reads as one native path in status and in the spawned argv.
+        return os.path.normpath(found[0])
     from agent.anthropic_adapter import find_claude_code_cli
 
     return find_claude_code_cli(command)

tests/hermes_cli/test_external_process_auth_status.py

@@ -80,6 +80,25 @@ def test_external_process_status_finds_user_local_cli_outside_backend_path(
     assert resolve_external_process_provider_credentials("copilot-acp")["command"] == str(cli)
 
 
+@pytest.mark.platforms("windows")
+def test_external_process_status_finds_user_profile_local_cli_as_native_path(
+    tmp_path, monkeypatch, _clean_copilot_env
+):
+    """The Windows user-local hit is one native path, not a mixed-separator join."""
+    local_bin = tmp_path / ".local" / "bin"
+    local_bin.mkdir(parents=True)
+    cli = local_bin / "copilot.exe"
+    cli.write_text("", encoding="utf-8")
+    monkeypatch.setenv("PATH", str(tmp_path / "backend-bin"))
+
+    status = get_external_process_provider_status("copilot-acp")
+    resolved = status["resolved_command"]
+
+    assert status["configured"] is True
+    assert "/" not in resolved and os.path.samefile(resolved, cli)
+    assert resolve_external_process_provider_credentials("copilot-acp")["command"] == resolved
+
+
 def test_external_process_status_resolves_relative_configured_path_from_cwd(
     tmp_path, monkeypatch, _clean_copilot_env
 ):