The wave-5 engine task (d69d9a3) found the literal
--no-default-features --features pg-lo config cannot compile the whole
crate: with no kv feature enabled, KvEngine/KvCursor go empty (E0004)
and the facade's by-reference dispatch matches are non-exhaustive
(references are always considered inhabited). Structural, not a bug —
per ADR-011 §4 every constructor mode pairs a kv engine, so a build
with zero kv engines is not a supported configuration (ADR-013 §4's
supported non-default configurations all include one).
The meaningful pure builds, verified on this tree:
- --no-default-features --features "pg-lo,mem" — check/test/clippy
green (115 tests ok server-less)
- --no-default-features --features "postgres,pg-lo" — check/clippy
green, test target compiles
Amended: engine-pg-lo (description + acceptance + gates),
engine-pg-lo-window (acceptance), store-pg-lo-construction (the full
structural reading + acceptance), review-wave-5 (gates). The engine
task's Notes/Summary already recorded the finding; the criteria text
now matches what was verified.
Verification: cargo test 69/19/3 ok, fmt --check green (docs-only
change).
Implement the pg-lo engine (ADR-009, POC #7 C1-C7) in src/pg_lo.rs
behind feature pg-lo (default-off), plus the shared-helper home the
task's design points resolve into src/pg_common.rs.
- Engine: seven Backend methods + put_staged; the lo_entries companion
table is the contract authority (list/size/has/CAS table-level;
pg_largeobject read only by the orphan sweep's candidate enumeration);
one-tx puts with 512 KiB lowrite statements (LOWRITE_CHUNK, the C2
knee), the descriptorless lo_get window cursor (READ_CHUNK; EOF
clamping + the unexpected-EOF clean failure), the held-tx staging
cursor aggregating 64 KiB windows, one-tx deletes, the complete
single-snapshot list, the 42P01 read-only virgin-store split, and the
crate-internal reap_orphans (scope-noted, planted-orphan contract
test). Posture deltas in the module doc (catalog space never
returned / VACUUM FULL runbook line / autovacuum inherited / the
cached-get capacity facts). Nothing of EngineFleetState; the window
family remains engine-pg-lo-window.
- Shared helpers (pg_err, 42P01, quote_identifier, size clamp, i64-nanos
encoding, build_pool, PgOpts, test janitors) move to src/pg_common.rs
gated cfg(any(postgres, pg-lo)); PgOpts's public re-export widens
(definition moved; crate::postgres::PgOpts path held by re-export);
src/postgres.rs's changes are mechanical swaps.
- LO isolation (C7 lesson): per-test dedicated databases + DatabaseJanitor
(WITH (FORCE)); zero LO/schema/database residue on the shared harness
db (pre-existing public.lo_entries exploration residue found and
removed).
- 18 in-module tests, env-driven (ALKBLOBS_PG_*), skipping cleanly
server-less; all green against the pglo-poc harness server.
Verified: cargo test (69/19/3), --features pg-lo live (87/19/3, 18/18
pg-lo), --features postgres live (103/36/3), --all-features (176/71/4);
clippy -D warnings green for default, pg-lo, postgres, all-features,
--no-default-features --features "pg-lo,mem" and "postgres,pg-lo";
cargo fmt --check; cargo doc --no-deps.
- engine-pg-lo: the Backend impl behind feature pg-lo (default-off) —
companion-table authority, one-tx staged put at the 512 KiB knee,
descriptorless lo_get windows, the orphan-recovery sweep, the
posture deltas recorded; the shared-helper/PgOpts/LO-isolation
design points named (LOs are database-level — the C7 lesson cited
so it is not rediscovered)
- engine-pg-lo-window: the EngineWindowState impl per ADR-012 §5's
pg-lo row — gc_window only, no fleet family anywhere
- store-pg-lo-construction: LargeEngine::PgLo slotting (the large
sub-enum design point), the consolidation + mem-pglo constructors
(the fleet-valid set completed, implicitly non-fleet), and the
one-window-host rule's store-core completion (dormancy + the
large-host sweep arm)
- suite-column-pg-lo: the second SKIP-posture column, two factories
spanning feature pairs, the dormancy row, zero LO residue in
teardown
- review-wave-5: the engine-wave gate; amendment A2 (janitor
adoption) verified here
Harness server cited in every server-touching task: dockerized
pglo-poc (postgres:16-alpine) on :15432, db blobs, postgres/poc
(verified live 2026-10-12); env-driven ALKBLOBS_PG_* settings, clean
server-less skips, acceptance requires green against the server.
Verification: cargo test 69/19/3 ok, clippy --all-targets -D warnings
green, fmt --check green (docs-only change).
glm-5.3-flash