Harden durable feed publication and recovery

[SMC17]

Summary

• Persist sealed feed packets before A/B multicast publication with a segmented, session-fenced WAL.
• Recover torn tails, reject corruption and sequence gaps, restore CRC-checked checkpoints, and serve exact indexed retransmission ranges.
• Integrate bounded live gap repair, fail-stop publication, runtime configuration, CI smoke coverage, and allocation-aware durability benchmarks.
• Reconcile governance with the real feed layout: five opcodes, 128-bit layout identities, conservative unframed compatibility, deterministic bitemporal reference data, and validated session state.

Evidence

• Release rebuild: 0 warnings, 0 errors
• Tests: 272 passed, 0 failed/skipped
• End-to-end smoke: unicast and redundant A/B multicast; 0 gaps, malformed packets, integrity failures, divergence, or stale books
• Seal + packet WAL: 813.7 ns median, 0 B/op on the recorded host
• Checkpoint + tail recovery: 8.45x faster than full replay
• Sparse ten-message lookup: 73.6 µs median versus 1,946.8 µs segment scan

Boundary

This remains a research system. Replicated sequencing, quorum commit, cross-site recovery, authenticated entitlements, regulatory controls, and production clock/NIC discipline remain explicit boundaries.