pub const DEFAULT_SCHEMA_EPOCH: u32 = 1;Expand description
Default schema-evolution epoch written by init_header.
Accounts initialised by pre-audit Hopper had the epoch region
zeroed, so 0 is treated as “legacy, equivalent to 1” by the
runtime checks that compare against an AccountLayout::SCHEMA_EPOCH.
Freshly-initialised accounts now carry 1 so migrations can bump
monotonically without any lookback.