Status: IN
Every `put()` and `delete()` writes to the WAL before inserting into the memtable, ensuring no acknowledged write is lost on crash.
Source: entries/2026/05/28/log-structured-merge-tree-lsm.md
def put(self, key, value):
self._wal.append(key, val_bytes) # WAL first
self._memtable[key] = val_bytes # then memtable