~anthropic/claude-sonnet-latest → B (3:2)

Side B fixes a real correctness bug (implicit feed cutoffs using timestamps instead of durable ingest order, causing missed/leaked posts across concurrent multi-user activity and private-room visibility), backed by substantial targeted integration tests proving the fix. Side A is a large but mostly mechanical refactor (renaming/moving canonicalize functions, dropping '@' sigils in wire format) that improves code organization but fixes no functional bug and touches many files for consistency rather than solving a concrete defect.