test(metrics): isolate large summary seed persistence across reopen

Release qualification crashed in historical baseline SQLite ingestion during the workloads-summary seed. Preserve a metrics-only diagnostic for the same 84,000-row batch shape, with row-count and integrity checks before and after reopen, without the HTTP or reflection fixtures. This does not reproduce or fix the unexplained crash.

Validation: ten focused runs on Go 1.26.7 and one on Go 1.26.8 passed; a one-repeat race run passed. The three-repeat race run timed out at 180 seconds during its final integrity check and remains retained evidence. Omitting the final seed batch makes the row-count assertion fail.
Change-source: pulse-maintainer

pkg/metrics/store_large_seed_test.go

@@ -0,0 +1,94 @@
+package metrics
+
+import (
+	"fmt"
+	"path/filepath"
+	"testing"
+	"time"
+)
+
+// Exercise the ingestion shape from the workloads-summary benchmark without
+// its HTTP, reflection or monitor fixtures. A historical benchmark crashed in
+// SQLite during the second synchronous seed; this is a diagnostic invariant,
+// not a reproducer or a claim that the unexplained crash has been repaired.
+func TestStoreLargeSummarySeedSurvivesReopen(t *testing.T) {
+	cfg := DefaultConfig(t.TempDir())
+	cfg.DBPath = filepath.Join(filepath.Dir(cfg.DBPath), "summary-seed.db")
+	cfg.FlushInterval = time.Hour
+	cfg.WriteBufferSize = 10_000
+	store, err := NewStore(cfg)
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Cleanup(func() {
+		if store != nil {
+			if err := store.Close(); err != nil {
+				t.Error(err)
+			}
+		}
+	})
+	base := time.Now().Add(-4 * time.Hour).UTC().Truncate(time.Second)
+	for _, group := range []struct {
+		kind  string
+		count int
+	}{{"vm", 30}, {"container", 20}, {"dockerContainer", 20}} {
+		batch := make([]WriteMetric, 0, group.count*5*240)
+		for r := 0; r < group.count; r++ {
+			for _, metric := range []string{"cpu", "memory", "disk", "netin", "netout"} {
+				for p := 0; p < 240; p++ {
+					batch = append(batch, WriteMetric{
+						ResourceType: group.kind, ResourceID: fmt.Sprintf("%s-%d", group.kind, r),
+						MetricType: metric, Value: float64((r + p) % 100),
+						Timestamp: base.Add(time.Duration(p) * time.Minute), Tier: TierMinute,
+					})
+				}
+			}
+		}
+		store.WriteBatchSync(batch)
+	}
+	check := func() {
+		t.Helper()
+		var count int
+		if err := store.db.QueryRow("SELECT COUNT(*) FROM metrics WHERE tier = ?", string(TierMinute)).Scan(&count); err != nil {
+			t.Fatal(err)
+		}
+		if count != 84_000 {
+			t.Fatalf("persisted minute rows = %d, want 84000", count)
+		}
+		rows, err := store.db.Query("PRAGMA integrity_check")
+		if err != nil {
+			t.Fatal(err)
+		}
+		defer rows.Close()
+		var results int
+		for rows.Next() {
+			var result string
+			if err := rows.Scan(&result); err != nil {
+				t.Fatal(err)
+			}
+			if result != "ok" {
+				t.Errorf("integrity_check: %s", result)
+			}
+			results++
+		}
+		if err := rows.Err(); err != nil {
+			t.Fatal(err)
+		}
+		if results != 1 {
+			t.Fatalf("integrity_check returned %d rows, want one ok", results)
+		}
+	}
+	check()
+	if err := store.Close(); err != nil {
+		t.Fatal(err)
+	}
+	store = nil
+	store, err = NewStore(cfg)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := store.WaitForMaintenance(10 * time.Second); err != nil {
+		t.Fatal(err)
+	}
+	check()
+}