feat: optimisation globale des performances #86 (scan differentiel, excalidraw differe, garde-fou replace; inverted index/PDF lazy/caps regex deja livres via BUG-033/040/025)

backend/services/mutations.py

@@ -26,6 +26,11 @@ from backend.services.vaults import get_vault_root
 
 logger = logging.getLogger("obsigate.services.mutations")
 
+# #86: per-file size cap for find/replace passes (CPU guard — complements the
+# BUG-025 regex caps). Files larger than this are skipped instead of being
+# read fully into memory and scanned with a user-supplied pattern.
+MAX_REPLACE_FILE_BYTES = 5_000_000
+
 # Skeleton injected into empty ``.excalidraw`` files (mirrors the route logic).
 _EXCALIDRAW_SKELETON = (
     '{"type":"excalidraw","version":2,"elements":[],'
@@ -509,6 +514,16 @@ def replace_in_files(
             continue
         if not file_path.exists() or not file_path.is_file():
             continue
+        # #86 CPU guard: skip files too large to scan safely in one pass.
+        try:
+            if file_path.stat().st_size > MAX_REPLACE_FILE_BYTES:
+                logger.warning(
+                    "replace_in_files: skipping oversized file %s/%s (%d bytes)",
+                    result_vault, result["path"], file_path.stat().st_size,
+                )
+                continue
+        except OSError:
+            continue
         try:
             original = file_path.read_text(encoding="utf-8", errors="replace")
         except OSError: