The hand-rolled dump writer stored index cells fully inline regardless of payload size. SQLite's format spills index payloads above the max-local threshold (16,422 bytes at the 64 KB page size) to overflow pages, so a long key written inline makes the reader interpret key bytes as an overflow page number: PRAGMA integrity_check reported 'invalid page number 0x43654C6C' (ASCII from the key text) in idx_nodes_name on elasticsearch (very long Section names), and name lookups on that index silently returned nothing. write_index_btree now rewrites oversized cells (varint + local prefix + overflow chain via write_overflow_pages) before page building; promoted separators carry their chains with them. Reproduce-first: sw_long_index_keys_overflow (20 KB name; integrity_check failed pre-fix, ok post-fix). Also escapes the remaining raw text interpolations in DATA_FLOWS route props and HANDLES handler QNs (the ~51-edge malformed tail after 6c04ab7).