A single append authority per space serializes appends into a total order: at
most one node holds a space's lease; only the holder writes, non-holders forward
their append intent to the holder. Leases are time-bounded and re-grantable, so
a dead holder's lease expires and a new node resumes from the log head (seq stays
contiguous). A stale ex-holder discovers it is no longer the holder and forwards
rather than writing, so a partitioned node cannot fork the log. Works over both
in-memory and git stores. Single-coordinator only (distributed leasing out of scope).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>