perf(store): resolution ref-index window — kernel-scale resolution 423→276s, 8c envelope ≈11min (§4d round 2) (#1369)

Store-architecture arc round 2. The batched resolution loop reads
unresolved_refs ONLY through the status index + the PK keyset pager;
the other five ref indexes (from_node, name, file_path, from_name,
failed_tail) serve sync-time paths — yet every per-batch DELETE of
resolved refs maintained all of them, the biggest single main-thread
stage on the dubbo profile (deletes 1.2s of a 5.4s resolution phase)
and 50-81s at kernel scale.

beginBulkRefLoad/endBulkRefLoad on DatabaseConnection, threaded as
refIndexLoad hooks next to the existing bulkEdgeLoad pair with the
same minRefsForPool gate (small syncs never pay): drop the five for
the loop, rebuild each in one scan at the end — where the table holds
only the surviving FAILED refs (resolved rows are deleted by then),
so the recreate is near-free. Crash inside the window heals on the
next open (schema.sql re-applies CREATE INDEX IF NOT EXISTS).

Measured:
- dubbo: deletes 1.2 → 0.2s, marks 0.6 → 0.3s, recreate 219ms; wall
  ~8.5s flat — the freed main-lane time shifts into settle (the worker
  lane now binds the double-buffer at medium scale).
- Linux kernel 8c: resolution 423.4 → 275.9s (deletes 50-81 → 3.2s,
  backpressure 16.8 → 7.4s — fewer index writes mean less WAL and
  cheaper folds), ref recreate 10.3s. Envelope ≈ 11.0min, from the
  14.8min pre-arc best; <10min-on-8c now needs ~1 more minute.

Gates: dubbo/gson dumps byte-identical; linux counts exact
2,049,153/6,413,518 and dump sha 6dd1185b… reproduced (10,446,478
lines); full suite green ×2 (153 files / 2588 tests).

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

docs/design/rust-kernel-migration-plan.md

@@ -543,6 +543,30 @@ gap. Multi-file write transactions are likely ~zero on the fastInit path
 batching); buffer→bind remains a CPU-side option if the writer re-emerges as
 the wall.
 
+**Store-arc round 2 SHIPPED (2026-07-19): resolution ref-index window.** The
+batched resolution loop reads unresolved_refs ONLY through the status index
++ PK keyset pager; the other five ref indexes (from_node, name, file_path,
+from_name, failed_tail) serve sync-time paths — yet every per-batch DELETE
+maintained all of them. `beginBulkRefLoad`/`endBulkRefLoad` (same
+`minRefsForPool` gate as the edge window) drop the five for the loop and
+rebuild at the end, where the table holds only the surviving failed refs
+(resolved rows are deleted by then), making the recreate near-free.
+
+- **dubbo**: deletes 1.2 → 0.2s, marks 0.6 → 0.3s (recreate 219ms) — but the
+  wall stayed ~8.5s: the freed main-lane time moved into `settle` (the
+  worker lane now binds the double-buffer). The honest read: at medium
+  scale, resolution's floor is now the WORKER lane + pool spin-up, not the
+  writer.
+- **Linux kernel 8c: resolution 423.4 → 275.9s** — deletes 50-81 → **3.2s**,
+  backpressure 16.8 → 7.4s (fewer index writes → less WAL → cheaper folds,
+  compounding), ref recreate 10.3s, edge recreate 26.8s. Synthesis 149.0s.
+  **Envelope ≈ 11.0min** (phase sum 659.7s) — from 14.8min best-ever before
+  this arc's rounds. **The <10min-on-8c target needs ~1 more minute**; the
+  remaining mass is parse-loop 190s (extraction-bound on linux — R7b's
+  wasm-deferred C tail + the store lane) and synthesis 149s.
+- Gates: dubbo/gson dumps byte-identical, linux counts exact + dump sha
+  `6dd1185b…` reproduced, suite green ×2.
+
 ## 4. Per-language tracker
 
 Tiers: **T1** = mostly `.scm` + mapping config. **T2** = needs bespoke pre/post passes kept