Epic: Atomic programs #191

Outcome

Make programs durable and visible as one committed revision. T01–T03 form the R2 engine checkpoint; T04 completes cross-instance gateway turn idempotency in R3. Keep #131 open until both engine and gateway acceptance pass.

Child issues

• Atomic programs: transaction WAL envelope and all-or-nothing replay #168
• Atomic programs: staged fact mutations and one-revision publication #169
• Atomic programs: transactional rules/schema and explicit command boundaries #170
• Gateway: durable turn idempotency and message-index reservation #178
• Atomic multi-statement programs (stage then commit, one WAL record) #131

Completion

Keep this tracking issue open until its selected release scope passes. Child issues in a later milestone remain visibly deferred; a partial slice does not complete a broader issue. Every change runs the performance pipeline in #163 before a pull request.