open() derived the delta path as "${db_path}.delta" (e.g. "db3.json.delta")
while checkpoint_store() writes via db_path.with_extension("delta")
(e.g. "db3.delta"). On reopen, load_base_plus_delta therefore read a
never-written path and silently skipped the delta, so post-checkpoint
changes were lost. Use db_p.with_extension("delta") in both places.
Also drop a no-op cp_seq.max(0) (u64 >= 0 always) to clear the clippy
-W clippy::unnecessary_min_or_max lint.
Verified: ./check all green; incremental_checkpoint_delta_model,
durable_checkpoint_and_replay, wal_recovery_after_crash pass in isolation.
- Add persist.rs: std-only NDJSON snapshot of the HashBackend store
(no serde) for the durable checkpoint + load_into_store replay.
- Add store.rs: ConcurrentStore = Mutex<HashBackend> live store + WAL
(newline-delimited JSON, group-commit fsync, idempotent seq-numbered
replay) + durable JSON checkpoint + bg flusher + startup replay.
- Recovery events (checkpoint failure, WAL fsync failure, WAL replay)
are written to a recovery.ndjson you asked to keep as the written backup
log, so any fall-back to JSON is recorded 'in writing'.
- Refactor cube-server to thread-per-connection over ConcurrentStore.
- query_doc_type / scan_prefix / linked_to / delete_raw added.
Verified: ./check (fmt, 7 unit tests, clippy -D warnings) all green;
./check stress drove 22,080 prog+run pairs (~368/s) over 60s, daemon
survived, latency prog~9us/run~13us mean.