Improve skills and document updates

src/plugin_helper/cli.py

@@ -572,6 +572,7 @@ def run(argv: list[str] | None = None) -> int:
             )
             print(f"Wrote plan: {path}")
             print(f"Changes: {len(plan['changes'])}")
+            print(f"Already match: {len(plan.get('unchanged', []))}")
             for warning in plan["warnings"]:
                 print(f"Warning: {warning}", file=sys.stderr)
             return 0

src/plugin_helper/planner.py

@@ -69,6 +69,11 @@ def _asset_matches_patterns(name: str, patterns: tuple[str, ...]) -> bool:
     return not patterns or any(fnmatch.fnmatch(name, pattern) for pattern in patterns)
 
 
+def _target_matches_live(instance_path: Path, change: dict[str, Any]) -> bool:
+    target = instance_path / ensure_relative(change["target"])
+    return target.is_file() and sha256_file(target) == change["sha256"]
+
+
 def _expand_required_dependencies(selected_ids: set[str], registry: Registry, lockfile: Lockfile) -> set[str]:
     locked_ids = {plugin.id for plugin in lockfile.plugins}
     expanded = set(selected_ids)
@@ -171,6 +176,8 @@ def create_plan(
                 }
             )
 
+    unchanged = [change for change in changes if _target_matches_live(instance_path, change)]
+    changes = [change for change in changes if change not in unchanged]
     plan = {
         "schemaVersion": 1,
         "createdAt": datetime.now(timezone.utc).isoformat().replace("+00:00", "Z"),
@@ -179,6 +186,7 @@ def create_plan(
         "beatSaberVersion": beat_saber_version,
         "warnings": warnings,
         "changes": changes,
+        "unchanged": unchanged,
     }
     if install_id:
         plan["installId"] = install_id