Implements ag-i788 W4.3. Cross-model ACKs recorded in Agent Mail: RubyMoose #214 and WindyCastle #213. Required checks green; merge proceeds under the recorded Cursor Bugbot non-required instability exception.
Resolve ag-qa01 by re-sourcing lesson recall contracts to markdown-as-source while preserving legacy bd memory lineage during W4 transition.\n\nQuorum: WindyCastle ACK #202 and RubyMoose ACK #203 at 6b47d8c5. Required checks green; Cursor Bugbot pending handled under recorded non-required Bugbot exception.