codebase: add encoding='utf-8' to all bare open() calls (PLW1514)

Closes the last Python-on-Windows UTF-8 exposure by making every
text-mode open() call explicit about its encoding.

Before: on Windows, bare open(path, 'r') defaults to the system
locale encoding (cp1252 on US-locale installs).  That means reading
any config/yaml/markdown/json file with non-ASCII content either
crashes with UnicodeDecodeError or silently mis-decodes bytes.

After: all 89 affected call sites in production code now pass
encoding='utf-8' explicitly.  Works identically on every platform
and every locale, no surprise behavior.

Mechanical sweep via:
  ruff check --preview --extend-select PLW1514 --unsafe-fixes --fix     --exclude 'tests,venv,.venv,node_modules,website,optional-skills,               skills,tinker-atropos,plugins' .

All 89 fixes have the same shape: open(x) or open(x, mode) became
open(x, encoding='utf-8') or open(x, mode, encoding='utf-8').  Nothing
else changed.  Every modified file still parses and the Windows/sandbox
test suite is still green (85 passed, 14 skipped, 0 failed across
tests/tools/test_code_execution_windows_env.py +
tests/tools/test_code_execution_modes.py + tests/tools/test_env_passthrough.py +
tests/test_hermes_bootstrap.py).

Scope notes:
  - tests/ excluded: test fixtures can use locale encoding intentionally
    (exercising edge cases).  If we want to tighten tests later that's
    a separate PR.
  - plugins/ excluded: plugin-specific conventions may differ; plugin
    authors own their code.
  - optional-skills/ and skills/ excluded: skill scripts are user-authored
    and we don't want to mass-edit them.
  - website/ and tinker-atropos/ excluded: vendored / generated content.

46 files touched, 89 +/- lines (symmetric replacement).  No behavior
change on POSIX or on Windows when the file is ASCII; bug fix on
Windows when the file contains non-ASCII.

hermes_cli/backup.py

@@ -573,7 +573,7 @@ def create_quick_snapshot(
         "total_size": sum(manifest.values()),
         "files": manifest,
     }
-    with open(snap_dir / "manifest.json", "w") as f:
+    with open(snap_dir / "manifest.json", "w", encoding="utf-8") as f:
         json.dump(meta, f, indent=2)
 
     # Auto-prune
@@ -599,7 +599,7 @@ def list_quick_snapshots(
         manifest_path = d / "manifest.json"
         if manifest_path.exists():
             try:
-                with open(manifest_path) as f:
+                with open(manifest_path, encoding="utf-8") as f:
                     results.append(json.load(f))
             except (json.JSONDecodeError, OSError):
                 results.append({"id": d.name, "file_count": 0, "total_size": 0})
@@ -629,7 +629,7 @@ def restore_quick_snapshot(
     if not manifest_path.exists():
         return False
 
-    with open(manifest_path) as f:
+    with open(manifest_path, encoding="utf-8") as f:
         meta = json.load(f)
 
     restored = 0

hermes_cli/config.py

@@ -212,7 +212,7 @@ def get_container_exec_info() -> Optional[dict]:
 
     try:
         info = {}
-        with open(container_mode_file, "r") as f:
+        with open(container_mode_file, "r", encoding="utf-8") as f:
             for line in f:
                 line = line.strip()
                 if "=" in line and not line.startswith("#"):
@@ -297,7 +297,7 @@ def _is_container() -> bool:
         return True
     # LXC / cgroup-based detection
     try:
-        with open("/proc/1/cgroup", "r") as f:
+        with open("/proc/1/cgroup", "r", encoding="utf-8") as f:
             cgroup_content = f.read()
         if "docker" in cgroup_content or "lxc" in cgroup_content or "kubepods" in cgroup_content:
             return True
@@ -3452,7 +3452,7 @@ def migrate_config(interactive: bool = True, quiet: bool = False) -> Dict[str, A
                         if not manifest_file.exists():
                             continue
                         try:
-                            with open(manifest_file) as _mf:
+                            with open(manifest_file, encoding="utf-8") as _mf:
                                 manifest = yaml.safe_load(_mf) or {}
                         except Exception:
                             manifest = {}

hermes_cli/doctor.py

@@ -598,7 +598,7 @@ def run_doctor(args):
         # Detect stale root-level model keys (known bug source — PR #4329)
         try:
             import yaml
-            with open(config_path) as f:
+            with open(config_path, encoding="utf-8") as f:
                 raw_config = yaml.safe_load(f) or {}
             stale_root_keys = [k for k in ("provider", "base_url") if k in raw_config and isinstance(raw_config[k], str)]
             if stale_root_keys:
@@ -1399,7 +1399,7 @@ def run_doctor(args):
         import yaml as _yaml
         _mem_cfg_path = HERMES_HOME / "config.yaml"
         if _mem_cfg_path.exists():
-            with open(_mem_cfg_path) as _f:
+            with open(_mem_cfg_path, encoding="utf-8") as _f:
                 _raw_cfg = _yaml.safe_load(_f) or {}
             _active_memory_provider = (_raw_cfg.get("memory") or {}).get("provider", "")
     except Exception:

hermes_cli/hooks.py

@@ -205,7 +205,7 @@ def _cmd_test(args) -> None:
 
     if getattr(args, "payload_file", None):
         try:
-            custom = json.loads(Path(args.payload_file).read_text())
+            custom = json.loads(Path(args.payload_file).read_text(encoding="utf-8"))
             if isinstance(custom, dict):
                 payload.update(custom)
             else:

hermes_cli/kanban_db.py

@@ -2835,7 +2835,7 @@ def _pid_alive(pid: Optional[int]) -> bool:
     # where we have a cheap, deterministic process-state probe.
     if sys.platform == "linux":
         try:
-            with open(f"/proc/{int(pid)}/status", "r") as f:
+            with open(f"/proc/{int(pid)}/status", "r", encoding="utf-8") as f:
                 for line in f:
                     if line.startswith("State:"):
                         # "State:\tZ (zombie)" → dead

hermes_cli/memory_setup.py

@@ -69,7 +69,7 @@ def _install_dependencies(provider_name: str) -> None:
 
     try:
         import yaml
-        with open(yaml_path) as f:
+        with open(yaml_path, encoding="utf-8") as f:
             meta = yaml.safe_load(f) or {}
     except Exception:
         return
@@ -377,7 +377,7 @@ def _write_env_vars(env_path: Path, env_writes: dict) -> None:
         if key not in updated_keys:
             new_lines.append(f"{key}={val}")
 
-    env_path.write_text("\n".join(new_lines) + "\n")
+    env_path.write_text("\n".join(new_lines) + "\n", encoding="utf-8")
 
 
 # ---------------------------------------------------------------------------

hermes_cli/model_catalog.py

@@ -173,7 +173,7 @@ def _read_disk_cache() -> tuple[dict[str, Any] | None, float]:
     except (OSError, FileNotFoundError):
         return (None, 0.0)
     try:
-        with open(path) as fh:
+        with open(path, encoding="utf-8") as fh:
             data = json.load(fh)
     except (OSError, json.JSONDecodeError):
         return (None, 0.0)
@@ -187,7 +187,7 @@ def _write_disk_cache(data: dict[str, Any]) -> None:
     try:
         path.parent.mkdir(parents=True, exist_ok=True)
         tmp = path.with_suffix(path.suffix + ".tmp")
-        with open(tmp, "w") as fh:
+        with open(tmp, "w", encoding="utf-8") as fh:
             json.dump(data, fh, indent=2)
             fh.write("\n")
         atomic_replace(tmp, path)

hermes_cli/oneshot.py

@@ -174,7 +174,7 @@ def run_oneshot(
     # Redirect stderr AND stdout to devnull for the entire call tree.
     # We'll print the final response to the real stdout at the end.
     real_stdout = sys.stdout
-    devnull = open(os.devnull, "w")
+    devnull = open(os.devnull, "w", encoding="utf-8")
 
     try:
         with redirect_stdout(devnull), redirect_stderr(devnull):

hermes_cli/plugins.py

@@ -870,7 +870,7 @@ class PluginManager:
             if yaml is None:
                 logger.warning("PyYAML not installed – cannot load %s", manifest_file)
                 return None
-            data = yaml.safe_load(manifest_file.read_text()) or {}
+            data = yaml.safe_load(manifest_file.read_text(encoding="utf-8")) or {}
 
             name = data.get("name", plugin_dir.name)
             key = f"{prefix}/{plugin_dir.name}" if prefix else name

hermes_cli/plugins_cmd.py

@@ -127,7 +127,7 @@ def _read_manifest(plugin_dir: Path) -> dict:
     try:
         import yaml
 
-        with open(manifest_file) as f:
+        with open(manifest_file, encoding="utf-8") as f:
             return yaml.safe_load(f) or {}
     except Exception as e:
         logger.warning("Failed to read plugin.yaml in %s: %s", plugin_dir, e)
@@ -703,7 +703,7 @@ def _discover_all_plugins() -> list:
             description = ""
             if yaml:
                 try:
-                    with open(manifest_file) as f:
+                    with open(manifest_file, encoding="utf-8") as f:
                         manifest = yaml.safe_load(f) or {}
                     name = manifest.get("name", d.name)
                     version = manifest.get("version", "")

hermes_cli/profiles.py

@@ -354,7 +354,7 @@ def _read_config_model(profile_dir: Path) -> tuple:
         return None, None
     try:
         import yaml
-        with open(config_path, "r") as f:
+        with open(config_path, "r", encoding="utf-8") as f:
             cfg = yaml.safe_load(f) or {}
         model_cfg = cfg.get("model", {})
         if isinstance(model_cfg, str):

hermes_cli/skills_hub.py

@@ -1257,7 +1257,7 @@ def do_snapshot_export(output_path: str, console: Optional[Console] = None) -> N
         sys.stdout.write(payload)
     else:
         out = Path(output_path)
-        out.write_text(payload)
+        out.write_text(payload, encoding="utf-8")
         c.print(f"[bold green]Snapshot exported:[/] {out}")
         c.print(f"[dim]{len(installed)} skill(s), {len(tap_list)} tap(s)[/]\n")
 
@@ -1274,7 +1274,7 @@ def do_snapshot_import(input_path: str, force: bool = False,
         return
 
     try:
-        snapshot = json.loads(inp.read_text())
+        snapshot = json.loads(inp.read_text(encoding="utf-8"))
     except json.JSONDecodeError:
         c.print(f"[bold red]Error:[/] Invalid JSON in {inp}\n")
         return

hermes_cli/web_server.py

@@ -692,7 +692,7 @@ def _tail_lines(path: Path, n: int) -> List[str]:
     if not path.exists():
         return []
     try:
-        text = path.read_text(errors="replace")
+        text = path.read_text(encoding="utf-8", errors="replace")
     except OSError:
         return []
     lines = text.splitlines()