feat: add self-update and improve skill selector

skiff/registry.py

@@ -26,6 +26,12 @@ def save_registry(data: dict[str, dict[str, Any]], path: Path | None = None) ->
     path.write_text(yaml_io.safe_dump(data, allow_unicode=True, sort_keys=False), encoding="utf-8")
 
 
+def registry_repo(entry: dict[str, Any]) -> str:
+    """Expand a local home-relative repo while leaving remote URLs unchanged."""
+    repo = str(entry.get("repo", ""))
+    return str(Path(repo).expanduser()) if repo.startswith("~") else repo
+
+
 def external_repo_path(entry: dict[str, Any]) -> Path:
     """Return the shared checkout path for a repo/ref pair."""
     from skiff.paths import EXTERNALS_DIR
@@ -37,9 +43,14 @@ def external_repo_path(entry: dict[str, Any]) -> Path:
 
 
 def external_checkout_path(name: str, entry: dict[str, Any]) -> Path:
-    """Prefer an existing pre-shared-cache checkout for compatibility."""
+    """Use a local repo directly, otherwise return its external checkout."""
     from skiff.paths import EXTERNALS_DIR
 
+    configured_repo = str(entry.get("repo", ""))
+    local_repo = Path(registry_repo(entry))
+    if configured_repo.startswith("~") and local_repo.is_dir():
+        return local_repo.resolve()
+
     legacy = EXTERNALS_DIR / name
     return legacy if legacy.is_dir() else external_repo_path(entry)