Constant V1_TENANT_PREPARE_SQL 

pub const V1_TENANT_PREPARE_SQL: &str = "-- Prepare a version 1 SQLite file for explicit tenant backfill.\n-- SQLite cannot add a NOT NULL column without a value, so preparation is\n-- nullable and activation rebuilds the tables after a complete backfill.\n-- The v1 global identity index remains in place until activation can replace\n-- it with the tenant-scoped identity index.\nALTER TABLE dovecote_events ADD COLUMN tenant_id TEXT;\nALTER TABLE dovecote_deliveries ADD COLUMN tenant_id TEXT;\n";

SQL that adds nullable tenant columns to a version 1 deployment.