feat: knowledge store staleness detector (#92)

scripts/knowledge_staleness_check.py

@@ -0,0 +1,221 @@
+#!/usr/bin/env python3
+"""
+Knowledge Store Staleness Detector
+
+Checks knowledge entries against their source files to detect staleness.
+An entry is stale when its source file has been modified since extraction.
+
+Usage:
+  python3 scripts/knowledge_staleness_check.py knowledge/index.json
+  python3 scripts/knowledge_staleness_check.py --repo /path/to/repo --index knowledge/index.json
+  python3 scripts/knowledge_staleness_check.py --index knowledge/index.json --fix
+
+Expected index.json format:
+{
+  "version": 1,
+  "facts": [
+    {
+      "fact": "...",
+      "category": "fact|pitfall|pattern|tool-quirk",
+      "repo": "repo-name",
+      "confidence": 0.8,
+      "source_file": "path/to/file.py",
+      "source_hash": "sha256:abcdef...",
+      "extracted_at": "2026-04-13T20:00:00Z"
+    }
+  ]
+}
+"""
+
+import argparse
+import hashlib
+import json
+import sys
+from pathlib import Path
+from typing import Optional
+
+
+def compute_file_hash(filepath: str) -> Optional[str]:
+    """Compute SHA-256 hash of a file. Returns None if file not found."""
+    path = Path(filepath)
+    if not path.exists():
+        return None
+    content = path.read_bytes()
+    return hashlib.sha256(content).hexdigest()[:16]
+
+
+def check_staleness(index_path: str, repo_root: str = None) -> dict:
+    """Check all entries in the knowledge index for staleness."""
+    index = Path(index_path)
+    if not index.exists():
+        return {"error": f"Index not found: {index_path}"}
+
+    data = json.loads(index.read_text())
+    facts = data.get("facts", [])
+
+    if not facts:
+        return {
+            "total": 0,
+            "stale": 0,
+            "fresh": 0,
+            "no_source": 0,
+            "missing_files": 0,
+            "stale_entries": [],
+        }
+
+    # Determine repo root
+    if repo_root:
+        root = Path(repo_root)
+    else:
+        root = index.parent.parent  # knowledge/index.json -> repo root
+
+    results = {
+        "total": len(facts),
+        "stale": 0,
+        "fresh": 0,
+        "no_source": 0,
+        "missing_files": 0,
+        "stale_entries": [],
+    }
+
+    for i, entry in enumerate(facts):
+        source_file = entry.get("source_file")
+        stored_hash = entry.get("source_hash")
+
+        if not source_file:
+            results["no_source"] += 1
+            continue
+
+        if not stored_hash:
+            # Entry has source file but no hash — consider stale
+            results["stale"] += 1
+            results["stale_entries"].append({
+                "index": i,
+                "fact": entry.get("fact", "")[:100],
+                "source_file": source_file,
+                "reason": "no_hash",
+            })
+            continue
+
+        # Compute current hash
+        full_path = root / source_file
+        current_hash = compute_file_hash(str(full_path))
+
+        if current_hash is None:
+            results["missing_files"] += 1
+            results["stale_entries"].append({
+                "index": i,
+                "fact": entry.get("fact", "")[:100],
+                "source_file": source_file,
+                "reason": "file_missing",
+            })
+        elif current_hash != stored_hash:
+            results["stale"] += 1
+            results["stale_entries"].append({
+                "index": i,
+                "fact": entry.get("fact", "")[:100],
+                "source_file": source_file,
+                "stored_hash": stored_hash,
+                "current_hash": current_hash,
+                "reason": "hash_mismatch",
+            })
+        else:
+            results["fresh"] += 1
+
+    return results
+
+
+def add_hashes_to_index(index_path: str, repo_root: str = None) -> dict:
+    """Add source hashes to entries that are missing them."""
+    index = Path(index_path)
+    data = json.loads(index.read_text())
+    facts = data.get("facts", [])
+
+    if repo_root:
+        root = Path(repo_root)
+    else:
+        root = index.parent.parent
+
+    updated = 0
+    skipped = 0
+
+    for entry in facts:
+        source_file = entry.get("source_file")
+        if not source_file or entry.get("source_hash"):
+            skipped += 1
+            continue
+
+        full_path = root / source_file
+        file_hash = compute_file_hash(str(full_path))
+        if file_hash:
+            entry["source_hash"] = file_hash
+            updated += 1
+
+    if updated > 0:
+        index.write_text(json.dumps(data, indent=2) + "\n")
+
+    return {"updated": updated, "skipped": skipped, "total": len(facts)}
+
+
+def report_staleness(results: dict) -> str:
+    """Format staleness check results as a report."""
+    lines = []
+    lines.append("=" * 50)
+    lines.append("KNOWLEDGE STORE STALENESS REPORT")
+    lines.append("=" * 50)
+    lines.append(f"Total entries:  {results['total']}")
+    lines.append(f"Fresh:          {results['fresh']}")
+    lines.append(f"Stale:          {results['stale']}")
+    lines.append(f"No source:      {results['no_source']}")
+    lines.append(f"Missing files:  {results['missing_files']}")
+    lines.append("")
+
+    if results["stale_entries"]:
+        lines.append("STALE ENTRIES:")
+        lines.append("-" * 50)
+        for entry in results["stale_entries"]:
+            lines.append(f"  [{entry['reason']}] {entry['source_file']}")
+            lines.append(f"    {entry['fact']}")
+            if entry.get("stored_hash") and entry.get("current_hash"):
+                lines.append(f"    stored:  {entry['stored_hash']}")
+                lines.append(f"    current: {entry['current_hash']}")
+            lines.append("")
+
+    if results["total"] > 0:
+        staleness_pct = results["stale"] / results["total"] * 100
+        lines.append(f"Staleness rate: {staleness_pct:.1f}%")
+    else:
+        lines.append("No entries to check.")
+
+    return "\n".join(lines)
+
+
+def main():
+    parser = argparse.ArgumentParser(description="Check knowledge store for stale entries")
+    parser.add_argument("--index", default="knowledge/index.json", help="Path to index.json")
+    parser.add_argument("--repo", help="Repository root (default: auto-detect from index path)")
+    parser.add_argument("--fix", action="store_true", help="Add missing hashes to index")
+    parser.add_argument("--json", action="store_true", help="Output JSON instead of report")
+    args = parser.parse_args()
+
+    if args.fix:
+        result = add_hashes_to_index(args.index, args.repo)
+        if args.json:
+            print(json.dumps(result, indent=2))
+        else:
+            print(f"Updated {result['updated']} entries with source hashes.")
+            print(f"Skipped {result['skipped']} (already had hashes or no source file).")
+    else:
+        results = check_staleness(args.index, args.repo)
+        if "error" in results:
+            print(f"Error: {results['error']}", file=sys.stderr)
+            sys.exit(1)
+
+        if args.json:
+            print(json.dumps(results, indent=2))
+        else:
+            print(report_staleness(results))
+
+
+if __name__ == "__main__":
+    main()