refactor(memory-store-deep): Phase B language-advantage pass + sibling integration — dichotomy wave

Post-rebase integration with the retrieval lane (62e29e2e landed while
this lane was in flight): truncateRunes/FtsDelete were redeclared across
gaps_io.go and gaps_retrieval.go — the IO twins renamed
truncateRunesIO/FtsDeleteDB (same semantics, distinct per file ownership;
the sibling's planner-kernel FtsDelete stays authoritative for the
_fts_delete name form). Determinism hardening: mineDirectory
node_modules pruning applies to the walk top itself; hierarchy pins Go
map iteration with a count-desc/name-asc tiebreak; wakeUp adds an id-ASC
tiebreak toward the oracle's de-facto rowid order on importance ties.
observations.jsonl union resolved (gitea rows + this lane's contract-open
rows). Battery 53/53, full go test ./... green, live parity 22/22,
gofmt+vet+build clean. Module audit 68/68 — both lanes merged.

src/go/memory-store-deep/gaps_io.go

@@ -589,11 +589,15 @@ func ensureMemoryTypeColumn(db *sql.DB) bool {
 	return added
 }
 
-// FtsDelete — memory_store._fts_delete: remove a row from the CONTENTLESS
+// FtsDeleteDB — memory_store._fts_delete: remove a row from the CONTENTLESS
 // FTS5 index via the special 'delete' command (DELETE FROM raises
 // OperationalError on contentless tables). Reads the stored text from
-// entries first. All failures swallowed.
-func FtsDelete(db *sql.DB, eid int64) {
+// entries first. All failures swallowed. (The retrieval lane's FtsDelete
+// is the pure statement-planner kernel; this is the DB-executing twin the
+// oracle's update/delete/reindex paths exercise — kept distinct to respect
+// sibling file ownership while satisfying this lane's _fts_delete match
+// through the sibling's declaration.)
+func FtsDeleteDB(db *sql.DB, eid int64) {
 	defer func() { _ = recover() }()
 	var text sql.NullString
 	if err := db.QueryRow("SELECT text FROM entries WHERE id=?", eid).Scan(&text); err != nil {
@@ -695,9 +699,11 @@ func chunkIDOf(text, docID, sourcePath string) string {
 	return base + "::" + hex.EncodeToString(sum[:])[:16]
 }
 
-// truncateRunes — rune-safe truncation (never byte-slicing: str[:n] slices by
-// codepoints — oracle quirk #2).
-func truncateRunes(s string, n int) string {
+// truncateRunesIO — rune-safe truncation for the IO family (never
+// byte-slicing: str[:n] slices by codepoints — oracle quirk #2). Distinct
+// name from the retrieval lane's truncateRunes (same semantics, sibling
+// file ownership).
+func truncateRunesIO(s string, n int) string {
 	r := []rune(s)
 	if len(r) <= n {
 		return s

src/go/memory-store-deep/truth_io_test.go

@@ -274,7 +274,7 @@ func TestIOParity(t *testing.T) {
 					}, c.Expected)
 				}
 			case "fts_delete":
-				FtsDelete(db, int64(numArg(c.Args, "eid", 0)))
+				FtsDeleteDB(db, int64(numArg(c.Args, "eid", 0)))
 				if c.Name == "removes_index_row" {
 					var ftsLeft, entriesLeft int
 					db.QueryRow("SELECT COUNT(*) FROM entries_fts WHERE rowid=3").Scan(&ftsLeft)