walcompare previously had no concept of a per-member compaction floor:
committed_lsn only capped the HIGH end (skip LSNs a member hasn't
caught up to yet), but the LOW end unconditionally expected every
member to hold raw WAL from LSN 1. A member that legitimately caught
up via a full-checkpoint snapshot holds no raw WAL at or below its own
checkpoint LSN by design (that range was entity-restored, not
WAL-replayed) -- so it was always flagged MISSING/divergent there,
regardless of whether the restore was correct. This is the root cause
ha-entity-snapshots task 7.1 diagnosed (committed_divergence=11 on an
otherwise-healthy soak) and raft-ha-core-safety task 5.10a's residual.
Adds member_snapshot_floor(): each member's own snap/ sibling
directory (matching the deployed <data>/wal + <data>/snap layout) is
scanned for the highest installed snap-<lsn>.{capnp,bin} file. Any LSN
at or below that member's own floor is excluded from its comparison
the same way an LSN above its own committed_lsn already is -- never
uniform/shared across members, since compaction is a per-member fact.
wc_status() gains a new "compacted" token distinct from "MISSING" so
the machine-readable report can tell the two apart.
Two new regression tests prove: (1) the floor correctly suppresses the
compacted range from comparison, and (2) it does NOT mask a genuine
divergence within the range a member still claims to hold. Caught and
fixed one bug myself before landing: the floor comparison was
off-by-one (< instead of <=), which the first test run surfaced
immediately (Expected 0 Was 1).
test_walcompare 17/17, test_ha_core_safety 28/0, test_config_repl
66/0, test_waldump 7/0 (all no-regression). Soak --selftest 17/17.
Per-member (lsn,term,pcrc,present) report + committed-vs-uncommitted
divergence classification via walcompare_report()/--report. Soak signal
(OK/exit-code) preserved. 4 new unit tests, all GREEN.
Diffs member WALs by (lsn -> term, pcrc) over the committed prefix, exits non-zero
on any committed-prefix divergence with the diverging LSN + per-member entry
identities. Reuses the canonical waldump decoder via a new per-entry visitor seam
(no second WAL parser). Detects same-LSN/diff-term and same-LSN/diff-content
divergences (the bug-851 class) that an LSN-range check would mask.
