fix(cli): warn once per path for UTF-32 .env refuse-to-mangle

Hot-reload and multi-entry load_hermes_dotenv can hit the same UTF-32
file repeatedly; gate the refuse-to-mangle warning on a module-level
seen-set (house style: _WARNED_KEYS sibling) so logs are not spammed.

hermes_cli/env_loader.py

@@ -23,6 +23,12 @@ _CREDENTIAL_SUFFIXES = ("_API_KEY", "_TOKEN", "_SECRET", "_KEY")
 # tests) don't spam the same warning multiple times.
 _WARNED_KEYS: set[str] = set()
 
+# Paths we've already emitted a UTF-32 refuse-to-mangle warning for.
+# load_hermes_dotenv can call _sanitize_env_file_if_needed multiple times
+# for the same file (user env + project env + hot-reload); once per path
+# is enough.
+_WARNED_UTF32_PATHS: set[str] = set()
+
 # Map of env-var name → source label ("bitwarden", etc.) for credentials
 # that were injected by an external secret source during load_hermes_dotenv().
 # Used by setup / `hermes model` flows to label detected credentials so
@@ -208,13 +214,16 @@ def _sanitize_env_file_if_needed(path: Path) -> None:
     if raw.startswith(codecs.BOM_UTF32_LE) or raw.startswith(codecs.BOM_UTF32_BE):
         # Lazy import keeps the module import block identical to #65124's
         # codecs/io additions so the two PRs auto-merge either order.
-        import logging
+        path_key = str(path.resolve())
+        if path_key not in _WARNED_UTF32_PATHS:
+            _WARNED_UTF32_PATHS.add(path_key)
+            import logging
 
-        logging.getLogger(__name__).warning(
-            "Skipping .env sanitize for %s: UTF-32 BOM detected; "
-            "leaving file untouched to avoid corruption",
-            path,
-        )
+            logging.getLogger(__name__).warning(
+                "Skipping .env sanitize for %s: UTF-32 BOM detected; "
+                "leaving file untouched to avoid corruption",
+                path,
+            )
         return
     if raw.startswith(codecs.BOM_UTF16_LE) or raw.startswith(codecs.BOM_UTF16_BE):
         # "utf-16" uses the BOM to select endianness and strips it.

tests/hermes_cli/test_env_loader.py

@@ -276,6 +276,35 @@ def test_utf32_be_bom_leaves_file_untouched(tmp_path, caplog):
     assert any("UTF-32" in r.message for r in caplog.records)
 
 
+def test_utf32_warning_fires_once_per_path(tmp_path, caplog, monkeypatch):
+    """Three sanitize calls on the same UTF-32 file → exactly one warning.
+
+    Matches house style for warn-once (module-level seen-set, same class as
+    ``_WARNED_KEYS``): hot-reload / multi-entry load must not spam logs.
+    """
+    import logging
+
+    import hermes_cli.env_loader as env_loader
+    from hermes_cli.env_loader import _sanitize_env_file_if_needed
+
+    # Isolate process-level seen-set so other tests' paths don't leak in.
+    monkeypatch.setattr(env_loader, "_WARNED_UTF32_PATHS", set())
+
+    env_file = tmp_path / ".env"
+    content = "HERMES_TEST_KEY=hello_utf32\nSECOND_KEY=world\n"
+    raw = codecs.BOM_UTF32_LE + content.encode("utf-32-le")
+    env_file.write_bytes(raw)
+
+    with caplog.at_level(logging.WARNING, logger="hermes_cli.env_loader"):
+        _sanitize_env_file_if_needed(env_file)
+        _sanitize_env_file_if_needed(env_file)
+        _sanitize_env_file_if_needed(env_file)
+
+    utf32_warnings = [r for r in caplog.records if "UTF-32" in r.message]
+    assert len(utf32_warnings) == 1
+    assert env_file.read_bytes() == raw
+
+
 def test_leading_replacement_char_does_not_rewrite(tmp_path):
     """errors=replace FFFD-on-first-line guard: do not persist mangling.