-- NULL retains the original per-field credential fallback for existing rows.
-- Explicit 1/0 selects one complete source without erasing stored device data.
ALTER TABLE routers ADD COLUMN use_global_switchos_credentials INTEGER
    CHECK (use_global_switchos_credentials IS NULL OR use_global_switchos_credentials IN (0, 1));
INSERT INTO rust_schema_migrations (version) VALUES (2);