chore: capture post-P0/P1 state for clean P2 start (working tree was dirty at task begin)

vfs/cache/cache.go

@@ -202,6 +202,10 @@ func (tc *TieredCache) promoteToFast(key string, reader io.ReadCloser) {
 		}
 	}
 
+	// P1-01: guard promotion ReadAll using already-fetched size (in addition to space check above)
+	if size > 0 && size > (1<<30) { // conservative 1GB hard limit on promotion reads (aligns with typical max_object_size)
+		return
+	}
 	// Read the entire file content
 	content, err := io.ReadAll(reader)
 	if err != nil {