feat(aggregation): Implement hash-based summary cache

src/summary_cache.py

@@ -0,0 +1,55 @@
+import hashlib
+import json
+from pathlib import Path
+from typing import Optional, Dict
+
+def get_file_hash(content: str) -> str:
+ """Returns SHA256 hash of the content."""
+ return hashlib.sha256(content.encode("utf-8")).hexdigest()
+
+class SummaryCache:
+ """
+    A hash-based cache for file summaries to avoid redundant processing.
+    Invalidates when content hash changes.
+    """
+ def __init__(self, cache_file: Optional[str] = None):
+  if cache_file:
+   self.cache_file = Path(cache_file)
+  else:
+   # Default relative to current working directory
+   self.cache_file = Path(".slop_cache/summary_cache.json")
+  self.cache: Dict[str, Dict[str, str]] = {}
+  self.load()
+
+ def load(self) -> None:
+  """Loads cache from disk."""
+  if self.cache_file.exists():
+   try:
+    with open(self.cache_file, "r", encoding="utf-8") as f:
+     self.cache = json.load(f)
+   except Exception:
+    self.cache = {}
+
+ def save(self) -> None:
+  """Saves cache to disk."""
+  try:
+   self.cache_file.parent.mkdir(parents=True, exist_ok=True)
+   with open(self.cache_file, "w", encoding="utf-8") as f:
+    json.dump(self.cache, f, indent=1)
+  except Exception:
+   pass
+
+ def get_summary(self, file_path: str, content_hash: str) -> Optional[str]:
+  """Returns cached summary if hash matches, otherwise None."""
+  entry = self.cache.get(file_path)
+  if entry and entry.get("hash") == content_hash:
+   return entry.get("summary")
+  return None
+
+ def set_summary(self, file_path: str, content_hash: str, summary: str) -> None:
+  """Stores summary in cache and saves to disk."""
+  self.cache[file_path] = {
+   "hash": content_hash,
+   "summary": summary
+  }
+  self.save()