{"id":"btree-recursive-insert-returns-union","text":"`_insert` returns a discriminated union: `None` (updated existing), `'inserted'` (new key, no split), or `(mid_key, new_page)` (split happened); root splits are handled in `put()`, not inside the recursion.","truth_value":"IN","source":"entries/2026/05/28/b-tree-storage-engine-btree.md","source_url":"","source_hash":"","justifications":[],"dependents":[],"metadata":{},"explanation":{"steps":[{"node":"btree-recursive-insert-returns-union","truth_value":"IN","reason":"premise"}]}}