Constant V1_TENANT_PREPARE_SQL 

pub const V1_TENANT_PREPARE_SQL: &str = "-- Prepare an existing Dovecote schema version 1 for explicit tenant backfill.\n--\n-- Run this in a maintenance window with the application still on the v1\n-- adapter.  It intentionally adds nullable columns only: no tenant value is\n-- invented here, and v2 must not be activated until every row is assigned by\n-- an operator-owned mapping. The v1 global identity index remains in place\n-- until activation can replace it with the tenant-scoped identity index.\n\nALTER TABLE dovecote_events ADD COLUMN tenant_id VARCHAR(255) COLLATE \"C\";\nALTER TABLE dovecote_deliveries ADD COLUMN tenant_id VARCHAR(255) COLLATE \"C\";\n";

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