- enum: add WO_WAL_DELTA = 4, existing 1/2/3 untouched (on-disk logs)
- wal.h: document kind 4's payload shape in the format docblock
- wal.h: declare wo_wal_append_delta(w, db, class_id, id, field_idx,
back_off, value) — back-pointer taken as a parameter, not looked up,
keeping the encoder ignorant of table/map state
- wal.c: implement it, modeled on wo_wal_append_insert's shape —
wput_u8/u32/u64 the header fields, enc_val the one field, stage()
- test_wal.c: new test_delta_record — stages a delta after an insert,
commits, then preads the raw record and asserts kind/class/id/
field_idx/back-pointer/value all round-trip; registered in main()
- nothing reads deltas back yet — decode/apply is a later task
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
(cherry picked from commit 9c6f832c0534a59e644c53b7cd2850581da12159)
shoney.arickathil
f1cf2d2f85