refactor(windows): unify windowless spawn form across the touched sites

windows_hide_flags() already returns 0 on POSIX (and creationflags=0 is
the no-op default there, exactly how server.py::_list_repo_files does it),
so drop the IS_WINDOWS import + ternary/one-use-dict gating and just pass
creationflags=windows_hide_flags() directly. Tests lose the now-pointless
IS_WINDOWS monkeypatch.

tests/test_windows_subprocess_no_window_flags.py

@@ -309,7 +309,6 @@ def test_checkpoint_manager_git_hides_windows(monkeypatch):
         captured.append((cmd, kwargs))
         return _Completed(stdout="clean\n")
 
-    monkeypatch.setattr(checkpoint_manager, "IS_WINDOWS", True)
     monkeypatch.setattr(checkpoint_manager, "windows_hide_flags", lambda: _CREATE_NO_WINDOW)
     monkeypatch.setattr(checkpoint_manager.subprocess, "run", fake_run)
 
@@ -328,7 +327,6 @@ def test_skills_hub_gh_token_hides_windows(monkeypatch):
         captured.append((cmd, kwargs))
         return _Completed(stdout="gho_from_cli\n")
 
-    monkeypatch.setattr(skills_hub, "IS_WINDOWS", True)
     monkeypatch.setattr(skills_hub, "windows_hide_flags", lambda: _CREATE_NO_WINDOW)
     monkeypatch.setattr(skills_hub.subprocess, "run", fake_run)
 

tools/checkpoint_manager.py

@@ -58,7 +58,7 @@ import subprocess
 import time
 from pathlib import Path
 from hermes_constants import get_hermes_home
-from hermes_cli._subprocess_compat import IS_WINDOWS, windows_hide_flags
+from hermes_cli._subprocess_compat import windows_hide_flags
 from typing import Dict, List, Optional, Set, Tuple
 
 from utils import env_int
@@ -322,10 +322,7 @@ def _run_git(
     env = _git_env(store, str(normalized_working_dir), index_file=index_file)
     cmd = ["git"] + list(args)
     allowed_returncodes = allowed_returncodes or set()
-    # Checkpoints run inside the console-less desktop/gateway backend; a bare
-    # git spawn there pops a fresh conhost window per call (status, add,
-    # commit, …) on Windows. No-op on POSIX.
-    _popen_kwargs = {"creationflags": windows_hide_flags()} if IS_WINDOWS else {}
+
     try:
         result = subprocess.run(
             cmd,
@@ -335,7 +332,10 @@ def _run_git(
             env=env,
             cwd=str(normalized_working_dir),
             stdin=subprocess.DEVNULL,
-            **_popen_kwargs,
+            # Checkpoints fire several bare git calls per turn from the
+            # console-less desktop/gateway backend; suppress the per-call
+            # conhost flash on Windows (no-op on POSIX).
+            creationflags=windows_hide_flags(),
         )
         ok = result.returncode == 0
         stdout = result.stdout.strip()
@@ -456,7 +456,7 @@ def _init_store(store: Path, working_dir: str) -> Optional[str]:
             capture_output=True, text=True,
             env=init_env, timeout=_GIT_TIMEOUT,
             stdin=subprocess.DEVNULL,
-            **({"creationflags": windows_hide_flags()} if IS_WINDOWS else {}),
+            creationflags=windows_hide_flags(),
         )
         if result.returncode != 0:
             return f"Shadow store init failed: {result.stderr.strip()}"

tools/skills_hub.py

@@ -26,7 +26,7 @@ from dataclasses import dataclass, field
 from datetime import datetime, timezone
 from pathlib import Path, PurePosixPath
 from hermes_constants import get_hermes_home
-from hermes_cli._subprocess_compat import IS_WINDOWS, windows_hide_flags
+from hermes_cli._subprocess_compat import windows_hide_flags
 from agent.skill_utils import is_excluded_skill_path
 from typing import Any, Dict, List, Optional, Tuple, Union
 from urllib.parse import urljoin, urlparse, urlunparse
@@ -303,7 +303,7 @@ class GitHubAuth:
                 ["gh", "auth", "token"],
                 capture_output=True, text=True, timeout=5,
                 stdin=subprocess.DEVNULL,
-                **({"creationflags": windows_hide_flags()} if IS_WINDOWS else {}),
+                creationflags=windows_hide_flags(),
             )
             if result.returncode == 0 and result.stdout.strip():
                 return result.stdout.strip()