feat: harden seat intent and expand HIL coverage

src/cognitive_agent/config_loader.py

@@ -6,7 +6,7 @@ import os
 from pathlib import Path
 
 
-def load_local_env(path: Path) -> None:
+def load_local_env(path: Path, *, override: bool = False) -> None:
     if not path.is_file():
         return
     for raw_line in path.read_text(encoding="utf-8").splitlines():
@@ -18,6 +18,9 @@ def load_local_env(path: Path) -> None:
         value = value.strip()
         if value[:1] == value[-1:] and value.startswith(("'", '"')):
             value = value[1:-1]
-        if key:
-            os.environ.setdefault(key, value)
+        if key and (override or not os.environ.get(key, "").strip()):
+            # A number of launchers export optional variables as empty strings.
+            # Treat those exactly like an unset value so a deliberate local
+            # development configuration is not silently shadowed.
+            os.environ[key] = value