Status: IN
The B-tree sibling chain is actively maintained during all structural mutations with a fixed wire format: splits write the new right page with the old leaf's next_sibling pointer before rewriting the old leaf, deletions patch the previous sibling's pointer to splice out the removed leaf, and the next_sibling field sits at a fixed byte offset (bytes 3-6) enabling reliable traversal without full page deserialization.
Split, delete, and read operations all respect and maintain the sibling chain through coordinated ordering and format invariants.
Depends on (SL): split-chain-rewiring-order, btree-leaf-sibling-patched-on-remove, btree-sibling-chain-fixed-offset