From b13eebfd7df79df01f7f798c3cfb7d565f0a1117 Mon Sep 17 00:00:00 2001
From: Jonathan Oppenheimer <jonathan.oppenheimer@avalabs.org>
Date: Tue, 29 Jul 2025 11:47:21 -0400
Subject: [PATCH 01/26] add combined metrics package

---
 vms/evm/metrics/metricstest/metrics.go        |  30 +++
 vms/evm/metrics/prometheus/enabled_test.go    |  29 +++
 vms/evm/metrics/prometheus/interfaces.go      |  14 ++
 vms/evm/metrics/prometheus/prometheus.go      | 209 ++++++++++++++++++
 vms/evm/metrics/prometheus/prometheus_test.go | 169 ++++++++++++++
 5 files changed, 451 insertions(+)
 create mode 100644 vms/evm/metrics/metricstest/metrics.go
 create mode 100644 vms/evm/metrics/prometheus/enabled_test.go
 create mode 100644 vms/evm/metrics/prometheus/interfaces.go
 create mode 100644 vms/evm/metrics/prometheus/prometheus.go
 create mode 100644 vms/evm/metrics/prometheus/prometheus_test.go

diff --git a/vms/evm/metrics/metricstest/metrics.go b/vms/evm/metrics/metricstest/metrics.go
new file mode 100644
index 000000000000..42416e696b81
--- /dev/null
+++ b/vms/evm/metrics/metricstest/metrics.go
@@ -0,0 +1,30 @@
+// Copyright (C) 2019-2025, Ava Labs, Inc. All rights reserved.
+// See the file LICENSE for licensing terms.
+
+package metricstest
+
+import (
+	"sync"
+	"testing"
+
+	"github.com/ava-labs/libevm/metrics"
+)
+
+var metricsLock sync.Mutex
+
+// WithMetrics enables go-ethereum metrics globally for the test.
+// If the [metrics.Enabled] is already true, nothing is done.
+// Otherwise, it is set to true and is reverted to false when the test finishes.
+func WithMetrics(t *testing.T) {
+	metricsLock.Lock()
+	t.Cleanup(func() {
+		metricsLock.Unlock()
+	})
+	if metrics.Enabled {
+		return
+	}
+	metrics.Enabled = true
+	t.Cleanup(func() {
+		metrics.Enabled = false
+	})
+}
diff --git a/vms/evm/metrics/prometheus/enabled_test.go b/vms/evm/metrics/prometheus/enabled_test.go
new file mode 100644
index 000000000000..a8c0b9a76dc7
--- /dev/null
+++ b/vms/evm/metrics/prometheus/enabled_test.go
@@ -0,0 +1,29 @@
+// Copyright (C) 2019-2025, Ava Labs, Inc. All rights reserved.
+// See the file LICENSE for licensing terms.
+
+package prometheus_test
+
+import (
+	"testing"
+
+	// NOTE: This test assumes that there are no imported packages that might
+	// change the default value of [metrics.Enabled]. It is therefore in package
+	// `prometheus_test` in case any other tests modify the variable. If any
+	// imports here or in the implementation do actually do so then this test
+	// may have false negatives.
+	"github.com/stretchr/testify/assert"
+
+	"github.com/ava-labs/libevm/metrics"
+)
+
+func TestMetricsEnabledByDefault(t *testing.T) {
+	assert.True(t, metrics.Enabled, "libevm/metrics.Enabled")
+
+	switch m := metrics.NewCounter().(type) {
+	case metrics.NilCounter:
+		t.Errorf("metrics.NewCounter() got %T; want %T", m, new(metrics.StandardCounter))
+	case *metrics.StandardCounter:
+	default:
+		t.Errorf("metrics.NewCounter() got unknown type %T", m)
+	}
+}
diff --git a/vms/evm/metrics/prometheus/interfaces.go b/vms/evm/metrics/prometheus/interfaces.go
new file mode 100644
index 000000000000..03c45ca6df27
--- /dev/null
+++ b/vms/evm/metrics/prometheus/interfaces.go
@@ -0,0 +1,14 @@
+// Copyright (C) 2019-2025, Ava Labs, Inc. All rights reserved.
+// See the file LICENSE for licensing terms.
+package prometheus
+
+import "github.com/ava-labs/libevm/metrics"
+
+var _ Registry = metrics.Registry(nil)
+
+type Registry interface {
+	// Call the given function for each registered metric.
+	Each(func(string, any))
+	// Get the metric by the given name or nil if none is registered.
+	Get(string) any
+}
diff --git a/vms/evm/metrics/prometheus/prometheus.go b/vms/evm/metrics/prometheus/prometheus.go
new file mode 100644
index 000000000000..feb2a9377082
--- /dev/null
+++ b/vms/evm/metrics/prometheus/prometheus.go
@@ -0,0 +1,209 @@
+// Copyright (C) 2019-2025, Ava Labs, Inc. All rights reserved.
+// See the file LICENSE for licensing terms.
+
+package prometheus
+
+import (
+	"errors"
+	"fmt"
+	"sort"
+	"strings"
+
+	"github.com/prometheus/client_golang/prometheus"
+
+	"github.com/ava-labs/libevm/metrics"
+
+	dto "github.com/prometheus/client_model/go"
+)
+
+// Gatherer implements [prometheus.Gatherer] interface by
+// gathering all metrics from the given Prometheus registry.
+type Gatherer struct {
+	registry Registry
+}
+
+var _ prometheus.Gatherer = (*Gatherer)(nil)
+
+// NewGatherer returns a [Gatherer] using the given registry.
+func NewGatherer(registry Registry) *Gatherer {
+	return &Gatherer{
+		registry: registry,
+	}
+}
+
+// Gather gathers metrics from the registry and converts them to
+// a slice of metric families.
+func (g *Gatherer) Gather() (mfs []*dto.MetricFamily, err error) {
+	// Gather and pre-sort the metrics to avoid random listings
+	var names []string
+	g.registry.Each(func(name string, i any) {
+		names = append(names, name)
+	})
+	sort.Strings(names)
+
+	mfs = make([]*dto.MetricFamily, 0, len(names))
+	for _, name := range names {
+		mf, err := metricFamily(g.registry, name)
+		if err != nil {
+			if errors.Is(err, errMetricSkip) {
+				continue
+			}
+			return nil, err
+		}
+		mfs = append(mfs, mf)
+	}
+
+	return mfs, nil
+}
+
+var (
+	errMetricSkip             = errors.New("metric skipped")
+	errMetricTypeNotSupported = errors.New("metric type is not supported")
+)
+
+func ptrTo[T any](x T) *T { return &x }
+
+func metricFamily(registry Registry, name string) (mf *dto.MetricFamily, err error) {
+	metric := registry.Get(name)
+	name = strings.ReplaceAll(name, "/", "_")
+
+	switch m := metric.(type) {
+	case metrics.NilCounter, metrics.NilCounterFloat64, metrics.NilEWMA,
+		metrics.NilGauge, metrics.NilGaugeFloat64, metrics.NilGaugeInfo,
+		metrics.NilHealthcheck, metrics.NilHistogram, metrics.NilMeter,
+		metrics.NilResettingTimer, metrics.NilSample, metrics.NilTimer:
+		return nil, fmt.Errorf("%w: %q metric is nil", errMetricSkip, name)
+
+	case metrics.Counter:
+		return &dto.MetricFamily{
+			Name: &name,
+			Type: dto.MetricType_COUNTER.Enum(),
+			Metric: []*dto.Metric{{
+				Counter: &dto.Counter{
+					Value: ptrTo(float64(m.Snapshot().Count())),
+				},
+			}},
+		}, nil
+	case metrics.CounterFloat64:
+		return &dto.MetricFamily{
+			Name: &name,
+			Type: dto.MetricType_COUNTER.Enum(),
+			Metric: []*dto.Metric{{
+				Counter: &dto.Counter{
+					Value: ptrTo(m.Snapshot().Count()),
+				},
+			}},
+		}, nil
+	case metrics.Gauge:
+		return &dto.MetricFamily{
+			Name: &name,
+			Type: dto.MetricType_GAUGE.Enum(),
+			Metric: []*dto.Metric{{
+				Gauge: &dto.Gauge{
+					Value: ptrTo(float64(m.Snapshot().Value())),
+				},
+			}},
+		}, nil
+	case metrics.GaugeFloat64:
+		return &dto.MetricFamily{
+			Name: &name,
+			Type: dto.MetricType_GAUGE.Enum(),
+			Metric: []*dto.Metric{{
+				Gauge: &dto.Gauge{
+					Value: ptrTo(m.Snapshot().Value()),
+				},
+			}},
+		}, nil
+	case metrics.Histogram:
+		snapshot := m.Snapshot()
+
+		quantiles := []float64{.5, .75, .95, .99, .999, .9999}
+		thresholds := snapshot.Percentiles(quantiles)
+		dtoQuantiles := make([]*dto.Quantile, len(quantiles))
+		for i := range thresholds {
+			dtoQuantiles[i] = &dto.Quantile{
+				Quantile: ptrTo(quantiles[i]),
+				Value:    ptrTo(thresholds[i]),
+			}
+		}
+
+		return &dto.MetricFamily{
+			Name: &name,
+			Type: dto.MetricType_SUMMARY.Enum(),
+			Metric: []*dto.Metric{{
+				Summary: &dto.Summary{
+					SampleCount: ptrTo(uint64(snapshot.Count())), //nolint:gosec
+					SampleSum:   ptrTo(float64(snapshot.Sum())),
+					Quantile:    dtoQuantiles,
+				},
+			}},
+		}, nil
+	case metrics.Meter:
+		return &dto.MetricFamily{
+			Name: &name,
+			Type: dto.MetricType_GAUGE.Enum(),
+			Metric: []*dto.Metric{{
+				Gauge: &dto.Gauge{
+					Value: ptrTo(float64(m.Snapshot().Count())),
+				},
+			}},
+		}, nil
+	case metrics.Timer:
+		snapshot := m.Snapshot()
+
+		quantiles := []float64{.5, .75, .95, .99, .999, .9999}
+		thresholds := snapshot.Percentiles(quantiles)
+		dtoQuantiles := make([]*dto.Quantile, len(quantiles))
+		for i := range thresholds {
+			dtoQuantiles[i] = &dto.Quantile{
+				Quantile: ptrTo(quantiles[i]),
+				Value:    ptrTo(thresholds[i]),
+			}
+		}
+
+		return &dto.MetricFamily{
+			Name: &name,
+			Type: dto.MetricType_SUMMARY.Enum(),
+			Metric: []*dto.Metric{{
+				Summary: &dto.Summary{
+					SampleCount: ptrTo(uint64(snapshot.Count())), //nolint:gosec
+					SampleSum:   ptrTo(float64(snapshot.Sum())),
+					Quantile:    dtoQuantiles,
+				},
+			}},
+		}, nil
+	case metrics.ResettingTimer:
+		snapshot := m.Snapshot()
+		count := snapshot.Count()
+		if count == 0 {
+			return nil, fmt.Errorf("%w: %q resetting timer metric count is zero", errMetricSkip, name)
+		}
+
+		pvShortPercent := []float64{50, 95, 99}
+		thresholds := snapshot.Percentiles(pvShortPercent)
+		dtoQuantiles := make([]*dto.Quantile, len(pvShortPercent))
+		for i := range pvShortPercent {
+			dtoQuantiles[i] = &dto.Quantile{
+				Quantile: ptrTo(pvShortPercent[i]),
+				Value:    ptrTo(thresholds[i]),
+			}
+		}
+
+		return &dto.MetricFamily{
+			Name: &name,
+			Type: dto.MetricType_SUMMARY.Enum(),
+			Metric: []*dto.Metric{{
+				Summary: &dto.Summary{
+					SampleCount: ptrTo(uint64(count)), //nolint:gosec
+					SampleSum:   ptrTo(float64(count) * snapshot.Mean()),
+					Quantile:    dtoQuantiles,
+				},
+			}},
+		}, nil
+	case metrics.GaugeInfo:
+		// TODO(qdm12) handle this somehow maybe with dto.MetricType_UNTYPED
+		return nil, fmt.Errorf("%w: %q is a %T", errMetricSkip, name, metric)
+	default:
+		return nil, fmt.Errorf("%w: metric %q type %T", errMetricTypeNotSupported, name, metric)
+	}
+}
diff --git a/vms/evm/metrics/prometheus/prometheus_test.go b/vms/evm/metrics/prometheus/prometheus_test.go
new file mode 100644
index 000000000000..ef6d485384a1
--- /dev/null
+++ b/vms/evm/metrics/prometheus/prometheus_test.go
@@ -0,0 +1,169 @@
+// Copyright (C) 2019-2025, Ava Labs, Inc. All rights reserved.
+// See the file LICENSE for licensing terms.
+
+package prometheus
+
+import (
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/prometheus/common/expfmt"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"github.com/ava-labs/avalanchego/vms/evm/metrics/metricstest"
+	"github.com/ava-labs/libevm/metrics"
+)
+
+func TestGatherer_Gather(t *testing.T) {
+	metricstest.WithMetrics(t)
+
+	registry := metrics.NewRegistry()
+	register := func(t *testing.T, name string, collector any) {
+		t.Helper()
+		err := registry.Register(name, collector)
+		require.NoErrorf(t, err, "registering collector %q", name)
+	}
+
+	counter := metrics.NewCounter()
+	counter.Inc(12345)
+	register(t, "test/counter", counter)
+
+	counterFloat64 := metrics.NewCounterFloat64()
+	counterFloat64.Inc(1.1)
+	register(t, "test/counter_float64", counterFloat64)
+
+	gauge := metrics.NewGauge()
+	gauge.Update(23456)
+	register(t, "test/gauge", gauge)
+
+	gaugeFloat64 := metrics.NewGaugeFloat64()
+	gaugeFloat64.Update(34567.89)
+	register(t, "test/gauge_float64", gaugeFloat64)
+
+	gaugeInfo := metrics.NewGaugeInfo()
+	gaugeInfo.Update(metrics.GaugeInfoValue{"key": "value"})
+	register(t, "test/gauge_info", gaugeInfo) // skipped
+
+	sample := metrics.NewUniformSample(1028)
+	histogram := metrics.NewHistogram(sample)
+	register(t, "test/histogram", histogram)
+
+	meter := metrics.NewMeter()
+	t.Cleanup(meter.Stop)
+	meter.Mark(9999999)
+	register(t, "test/meter", meter)
+
+	timer := metrics.NewTimer()
+	t.Cleanup(timer.Stop)
+	timer.Update(20 * time.Millisecond)
+	timer.Update(21 * time.Millisecond)
+	timer.Update(22 * time.Millisecond)
+	timer.Update(120 * time.Millisecond)
+	timer.Update(23 * time.Millisecond)
+	timer.Update(24 * time.Millisecond)
+	register(t, "test/timer", timer)
+
+	resettingTimer := metrics.NewResettingTimer()
+	register(t, "test/resetting_timer", resettingTimer)
+	resettingTimer.Update(time.Second) // must be after register call
+
+	emptyResettingTimer := metrics.NewResettingTimer()
+	register(t, "test/empty_resetting_timer", emptyResettingTimer)
+
+	emptyResettingTimer.Update(time.Second) // no effect because of snapshot below
+	register(t, "test/empty_resetting_timer_snapshot", emptyResettingTimer.Snapshot())
+
+	registerNilMetrics(t, register)
+
+	gatherer := NewGatherer(registry)
+
+	families, err := gatherer.Gather()
+	require.NoError(t, err)
+
+	const expectedString = `
+# TYPE test_counter counter
+test_counter 12345
+# TYPE test_counter_float64 counter
+test_counter_float64 1.1
+# TYPE test_gauge gauge
+test_gauge 23456
+# TYPE test_gauge_float64 gauge
+test_gauge_float64 34567.89
+# TYPE test_histogram summary
+test_histogram{quantile="0.5"} 0
+test_histogram{quantile="0.75"} 0
+test_histogram{quantile="0.95"} 0
+test_histogram{quantile="0.99"} 0
+test_histogram{quantile="0.999"} 0
+test_histogram{quantile="0.9999"} 0
+test_histogram_sum 0
+test_histogram_count 0
+# TYPE test_meter gauge
+test_meter 9.999999e+06
+# TYPE test_resetting_timer summary
+test_resetting_timer{quantile="50"} 1e+09
+test_resetting_timer{quantile="95"} 1e+09
+test_resetting_timer{quantile="99"} 1e+09
+test_resetting_timer_sum 1e+09
+test_resetting_timer_count 1
+# TYPE test_timer summary
+test_timer{quantile="0.5"} 2.25e+07
+test_timer{quantile="0.75"} 4.8e+07
+test_timer{quantile="0.95"} 1.2e+08
+test_timer{quantile="0.99"} 1.2e+08
+test_timer{quantile="0.999"} 1.2e+08
+test_timer{quantile="0.9999"} 1.2e+08
+test_timer_sum 2.3e+08
+test_timer_count 6
+`
+	var (
+		stringReader = strings.NewReader(expectedString)
+		parser       expfmt.TextParser
+	)
+	expectedMetrics, err := parser.TextToMetricFamilies(stringReader)
+	require.NoError(t, err)
+
+	assert.Len(t, families, len(expectedMetrics))
+	for i, got := range families {
+		require.NotNil(t, *got.Name)
+
+		want := expectedMetrics[*got.Name]
+		assert.Equal(t, want, got, i)
+	}
+
+	register(t, "unsupported", metrics.NewHealthcheck(nil))
+	families, err = gatherer.Gather()
+	assert.ErrorIs(t, err, errMetricTypeNotSupported)
+	assert.Empty(t, families)
+}
+
+func registerNilMetrics(t *testing.T, register func(t *testing.T, name string, collector any)) {
+	metrics.Enabled = false
+	defer func() { metrics.Enabled = true }()
+	nilCounter := metrics.NewCounter()
+	register(t, "nil/counter", nilCounter)
+	nilCounterFloat64 := metrics.NewCounterFloat64()
+	register(t, "nil/counter_float64", nilCounterFloat64)
+	nilEWMA := &metrics.NilEWMA{}
+	register(t, "nil/ewma", nilEWMA)
+	nilGauge := metrics.NewGauge()
+	register(t, "nil/gauge", nilGauge)
+	nilGaugeFloat64 := metrics.NewGaugeFloat64()
+	register(t, "nil/gauge_float64", nilGaugeFloat64)
+	nilGaugeInfo := metrics.NewGaugeInfo()
+	register(t, "nil/gauge_info", nilGaugeInfo)
+	nilHealthcheck := metrics.NewHealthcheck(nil)
+	register(t, "nil/healthcheck", nilHealthcheck)
+	nilHistogram := metrics.NewHistogram(nil)
+	register(t, "nil/histogram", nilHistogram)
+	nilMeter := metrics.NewMeter()
+	register(t, "nil/meter", nilMeter)
+	nilResettingTimer := metrics.NewResettingTimer()
+	register(t, "nil/resetting_timer", nilResettingTimer)
+	nilSample := metrics.NewUniformSample(1028)
+	register(t, "nil/sample", nilSample)
+	nilTimer := metrics.NewTimer()
+	register(t, "nil/timer", nilTimer)
+}

From ff472523941e2ebc2012c05cddbb9930712b0645 Mon Sep 17 00:00:00 2001
From: Jonathan Oppenheimer <jonathan.oppenheimer@avalabs.org>
Date: Tue, 29 Jul 2025 11:53:33 -0400
Subject: [PATCH 02/26] support GaugeInfo from subnet-evm

---
 vms/evm/metrics/prometheus/prometheus.go | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/vms/evm/metrics/prometheus/prometheus.go b/vms/evm/metrics/prometheus/prometheus.go
index feb2a9377082..e0d503871ae0 100644
--- a/vms/evm/metrics/prometheus/prometheus.go
+++ b/vms/evm/metrics/prometheus/prometheus.go
@@ -44,10 +44,10 @@ func (g *Gatherer) Gather() (mfs []*dto.MetricFamily, err error) {
 	mfs = make([]*dto.MetricFamily, 0, len(names))
 	for _, name := range names {
 		mf, err := metricFamily(g.registry, name)
-		if err != nil {
-			if errors.Is(err, errMetricSkip) {
-				continue
-			}
+		switch {
+		case errors.Is(err, errMetricSkip):
+			continue
+		case err != nil:
 			return nil, err
 		}
 		mfs = append(mfs, mf)
@@ -73,7 +73,6 @@ func metricFamily(registry Registry, name string) (mf *dto.MetricFamily, err err
 		metrics.NilHealthcheck, metrics.NilHistogram, metrics.NilMeter,
 		metrics.NilResettingTimer, metrics.NilSample, metrics.NilTimer:
 		return nil, fmt.Errorf("%w: %q metric is nil", errMetricSkip, name)
-
 	case metrics.Counter:
 		return &dto.MetricFamily{
 			Name: &name,
@@ -114,6 +113,8 @@ func metricFamily(registry Registry, name string) (mf *dto.MetricFamily, err err
 				},
 			}},
 		}, nil
+	case metrics.GaugeInfo:
+		return nil, fmt.Errorf("%w: %q is a %T", errMetricSkip, name, m)
 	case metrics.Histogram:
 		snapshot := m.Snapshot()
 
@@ -200,9 +201,6 @@ func metricFamily(registry Registry, name string) (mf *dto.MetricFamily, err err
 				},
 			}},
 		}, nil
-	case metrics.GaugeInfo:
-		// TODO(qdm12) handle this somehow maybe with dto.MetricType_UNTYPED
-		return nil, fmt.Errorf("%w: %q is a %T", errMetricSkip, name, metric)
 	default:
 		return nil, fmt.Errorf("%w: metric %q type %T", errMetricTypeNotSupported, name, metric)
 	}

From 45f25b0d25d40d8d8dd7347a85e7cacb7fbc717d Mon Sep 17 00:00:00 2001
From: Jonathan Oppenheimer <jonathan.oppenheimer@avalabs.org>
Date: Tue, 29 Jul 2025 14:21:12 -0400
Subject: [PATCH 03/26] lint update

---
 vms/evm/metrics/prometheus/enabled_test.go    | 11 +++++------
 vms/evm/metrics/prometheus/interfaces.go      |  1 +
 vms/evm/metrics/prometheus/prometheus.go      | 15 +++++++--------
 vms/evm/metrics/prometheus/prometheus_test.go | 11 +++++------
 4 files changed, 18 insertions(+), 20 deletions(-)

diff --git a/vms/evm/metrics/prometheus/enabled_test.go b/vms/evm/metrics/prometheus/enabled_test.go
index a8c0b9a76dc7..f31605c15bf3 100644
--- a/vms/evm/metrics/prometheus/enabled_test.go
+++ b/vms/evm/metrics/prometheus/enabled_test.go
@@ -6,24 +6,23 @@ package prometheus_test
 import (
 	"testing"
 
+	"github.com/ava-labs/libevm/metrics"
 	// NOTE: This test assumes that there are no imported packages that might
 	// change the default value of [metrics.Enabled]. It is therefore in package
 	// `prometheus_test` in case any other tests modify the variable. If any
 	// imports here or in the implementation do actually do so then this test
 	// may have false negatives.
-	"github.com/stretchr/testify/assert"
-
-	"github.com/ava-labs/libevm/metrics"
+	"github.com/stretchr/testify/require"
 )
 
 func TestMetricsEnabledByDefault(t *testing.T) {
-	assert.True(t, metrics.Enabled, "libevm/metrics.Enabled")
+	require.True(t, metrics.Enabled, "libevm/metrics.Enabled")
 
 	switch m := metrics.NewCounter().(type) {
 	case metrics.NilCounter:
-		t.Errorf("metrics.NewCounter() got %T; want %T", m, new(metrics.StandardCounter))
+		require.Failf(t, "unexpected type", "metrics.NewCounter() got %T; want %T", m, new(metrics.StandardCounter))
 	case *metrics.StandardCounter:
 	default:
-		t.Errorf("metrics.NewCounter() got unknown type %T", m)
+		require.Failf(t, "unexpected type", "metrics.NewCounter() got unknown type %T", m)
 	}
 }
diff --git a/vms/evm/metrics/prometheus/interfaces.go b/vms/evm/metrics/prometheus/interfaces.go
index 03c45ca6df27..b8aa993453c0 100644
--- a/vms/evm/metrics/prometheus/interfaces.go
+++ b/vms/evm/metrics/prometheus/interfaces.go
@@ -1,5 +1,6 @@
 // Copyright (C) 2019-2025, Ava Labs, Inc. All rights reserved.
 // See the file LICENSE for licensing terms.
+
 package prometheus
 
 import "github.com/ava-labs/libevm/metrics"
diff --git a/vms/evm/metrics/prometheus/prometheus.go b/vms/evm/metrics/prometheus/prometheus.go
index e0d503871ae0..0745e90509d2 100644
--- a/vms/evm/metrics/prometheus/prometheus.go
+++ b/vms/evm/metrics/prometheus/prometheus.go
@@ -6,12 +6,11 @@ package prometheus
 import (
 	"errors"
 	"fmt"
-	"sort"
+	"slices"
 	"strings"
 
-	"github.com/prometheus/client_golang/prometheus"
-
 	"github.com/ava-labs/libevm/metrics"
+	"github.com/prometheus/client_golang/prometheus"
 
 	dto "github.com/prometheus/client_model/go"
 )
@@ -36,10 +35,10 @@ func NewGatherer(registry Registry) *Gatherer {
 func (g *Gatherer) Gather() (mfs []*dto.MetricFamily, err error) {
 	// Gather and pre-sort the metrics to avoid random listings
 	var names []string
-	g.registry.Each(func(name string, i any) {
+	g.registry.Each(func(name string, _ any) {
 		names = append(names, name)
 	})
-	sort.Strings(names)
+	slices.Sort(names)
 
 	mfs = make([]*dto.MetricFamily, 0, len(names))
 	for _, name := range names {
@@ -133,7 +132,7 @@ func metricFamily(registry Registry, name string) (mf *dto.MetricFamily, err err
 			Type: dto.MetricType_SUMMARY.Enum(),
 			Metric: []*dto.Metric{{
 				Summary: &dto.Summary{
-					SampleCount: ptrTo(uint64(snapshot.Count())), //nolint:gosec
+					SampleCount: ptrTo(uint64(snapshot.Count())),
 					SampleSum:   ptrTo(float64(snapshot.Sum())),
 					Quantile:    dtoQuantiles,
 				},
@@ -167,7 +166,7 @@ func metricFamily(registry Registry, name string) (mf *dto.MetricFamily, err err
 			Type: dto.MetricType_SUMMARY.Enum(),
 			Metric: []*dto.Metric{{
 				Summary: &dto.Summary{
-					SampleCount: ptrTo(uint64(snapshot.Count())), //nolint:gosec
+					SampleCount: ptrTo(uint64(snapshot.Count())),
 					SampleSum:   ptrTo(float64(snapshot.Sum())),
 					Quantile:    dtoQuantiles,
 				},
@@ -195,7 +194,7 @@ func metricFamily(registry Registry, name string) (mf *dto.MetricFamily, err err
 			Type: dto.MetricType_SUMMARY.Enum(),
 			Metric: []*dto.Metric{{
 				Summary: &dto.Summary{
-					SampleCount: ptrTo(uint64(count)), //nolint:gosec
+					SampleCount: ptrTo(uint64(count)),
 					SampleSum:   ptrTo(float64(count) * snapshot.Mean()),
 					Quantile:    dtoQuantiles,
 				},
diff --git a/vms/evm/metrics/prometheus/prometheus_test.go b/vms/evm/metrics/prometheus/prometheus_test.go
index ef6d485384a1..fbed23040e6e 100644
--- a/vms/evm/metrics/prometheus/prometheus_test.go
+++ b/vms/evm/metrics/prometheus/prometheus_test.go
@@ -8,12 +8,11 @@ import (
 	"testing"
 	"time"
 
+	"github.com/ava-labs/libevm/metrics"
 	"github.com/prometheus/common/expfmt"
-	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 
 	"github.com/ava-labs/avalanchego/vms/evm/metrics/metricstest"
-	"github.com/ava-labs/libevm/metrics"
 )
 
 func TestGatherer_Gather(t *testing.T) {
@@ -125,18 +124,18 @@ test_timer_count 6
 	expectedMetrics, err := parser.TextToMetricFamilies(stringReader)
 	require.NoError(t, err)
 
-	assert.Len(t, families, len(expectedMetrics))
+	require.Len(t, families, len(expectedMetrics))
 	for i, got := range families {
 		require.NotNil(t, *got.Name)
 
 		want := expectedMetrics[*got.Name]
-		assert.Equal(t, want, got, i)
+		require.Equal(t, want, got, i)
 	}
 
 	register(t, "unsupported", metrics.NewHealthcheck(nil))
 	families, err = gatherer.Gather()
-	assert.ErrorIs(t, err, errMetricTypeNotSupported)
-	assert.Empty(t, families)
+	require.ErrorIs(t, err, errMetricTypeNotSupported)
+	require.Empty(t, families)
 }
 
 func registerNilMetrics(t *testing.T, register func(t *testing.T, name string, collector any)) {

From 9a08a5868f1fe60e6ff15ae4027f95506d0debda Mon Sep 17 00:00:00 2001
From: Jonathan Oppenheimer <jonathan.oppenheimer@avalabs.org>
Date: Wed, 30 Jul 2025 10:24:00 -0400
Subject: [PATCH 04/26] Update vms/evm/metrics/metricstest/metrics.go

Co-authored-by: Stephen Buttolph <stephen@avalabs.org>
Signed-off-by: Jonathan Oppenheimer <147infiniti@gmail.com>
---
 vms/evm/metrics/metricstest/metrics.go | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/vms/evm/metrics/metricstest/metrics.go b/vms/evm/metrics/metricstest/metrics.go
index 42416e696b81..e63f91032b3f 100644
--- a/vms/evm/metrics/metricstest/metrics.go
+++ b/vms/evm/metrics/metricstest/metrics.go
@@ -17,9 +17,7 @@ var metricsLock sync.Mutex
 // Otherwise, it is set to true and is reverted to false when the test finishes.
 func WithMetrics(t *testing.T) {
 	metricsLock.Lock()
-	t.Cleanup(func() {
-		metricsLock.Unlock()
-	})
+	t.Cleanup(metricsLock.Unlock)
 	if metrics.Enabled {
 		return
 	}

From d5e51fe55dc1eb392b49f1dc3719a4a6a29c471f Mon Sep 17 00:00:00 2001
From: Jonathan Oppenheimer <jonathan.oppenheimer@avalabs.org>
Date: Wed, 30 Jul 2025 10:24:25 -0400
Subject: [PATCH 05/26] Update vms/evm/metrics/metricstest/metrics.go

Co-authored-by: Stephen Buttolph <stephen@avalabs.org>
Signed-off-by: Jonathan Oppenheimer <147infiniti@gmail.com>
---
 vms/evm/metrics/metricstest/metrics.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/vms/evm/metrics/metricstest/metrics.go b/vms/evm/metrics/metricstest/metrics.go
index e63f91032b3f..edd8a30ad29d 100644
--- a/vms/evm/metrics/metricstest/metrics.go
+++ b/vms/evm/metrics/metricstest/metrics.go
@@ -15,7 +15,7 @@ var metricsLock sync.Mutex
 // WithMetrics enables go-ethereum metrics globally for the test.
 // If the [metrics.Enabled] is already true, nothing is done.
 // Otherwise, it is set to true and is reverted to false when the test finishes.
-func WithMetrics(t *testing.T) {
+func WithMetrics(t testing.TB) {
 	metricsLock.Lock()
 	t.Cleanup(metricsLock.Unlock)
 	if metrics.Enabled {

From c1626678e783ced57ef980987fa2c403e99f0dd1 Mon Sep 17 00:00:00 2001
From: Jonathan Oppenheimer <jonathan.oppenheimer@avalabs.org>
Date: Wed, 30 Jul 2025 10:25:06 -0400
Subject: [PATCH 06/26] Update vms/evm/metrics/prometheus/enabled_test.go

Co-authored-by: Stephen Buttolph <stephen@avalabs.org>
Signed-off-by: Jonathan Oppenheimer <147infiniti@gmail.com>
---
 vms/evm/metrics/prometheus/enabled_test.go | 9 +--------
 1 file changed, 1 insertion(+), 8 deletions(-)

diff --git a/vms/evm/metrics/prometheus/enabled_test.go b/vms/evm/metrics/prometheus/enabled_test.go
index f31605c15bf3..0f772a655b7a 100644
--- a/vms/evm/metrics/prometheus/enabled_test.go
+++ b/vms/evm/metrics/prometheus/enabled_test.go
@@ -17,12 +17,5 @@ import (
 
 func TestMetricsEnabledByDefault(t *testing.T) {
 	require.True(t, metrics.Enabled, "libevm/metrics.Enabled")
-
-	switch m := metrics.NewCounter().(type) {
-	case metrics.NilCounter:
-		require.Failf(t, "unexpected type", "metrics.NewCounter() got %T; want %T", m, new(metrics.StandardCounter))
-	case *metrics.StandardCounter:
-	default:
-		require.Failf(t, "unexpected type", "metrics.NewCounter() got unknown type %T", m)
-	}
+	require.IsType(t, (*metrics.StandardCounter)(nil), metrics.NewCounter(), "metrics.NewCounter() returned wrong type")
 }

From 1ce92b94d3304b325b3b91b293684bcd6a75b51e Mon Sep 17 00:00:00 2001
From: Jonathan Oppenheimer <jonathan.oppenheimer@avalabs.org>
Date: Wed, 30 Jul 2025 10:25:40 -0400
Subject: [PATCH 07/26] Update vms/evm/metrics/prometheus/prometheus_test.go

Co-authored-by: Stephen Buttolph <stephen@avalabs.org>
Signed-off-by: Jonathan Oppenheimer <147infiniti@gmail.com>
---
 vms/evm/metrics/prometheus/prometheus_test.go | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/vms/evm/metrics/prometheus/prometheus_test.go b/vms/evm/metrics/prometheus/prometheus_test.go
index fbed23040e6e..f4281a6af9ab 100644
--- a/vms/evm/metrics/prometheus/prometheus_test.go
+++ b/vms/evm/metrics/prometheus/prometheus_test.go
@@ -139,6 +139,8 @@ test_timer_count 6
 }
 
 func registerNilMetrics(t *testing.T, register func(t *testing.T, name string, collector any)) {
+	// The NewXXX metrics functions return nil metrics types when the metrics
+	// are disabled.
 	metrics.Enabled = false
 	defer func() { metrics.Enabled = true }()
 	nilCounter := metrics.NewCounter()

From b82fcceaa42a098cd4c39bd81a65a4fd97de739d Mon Sep 17 00:00:00 2001
From: Jonathan Oppenheimer <jonathan.oppenheimer@avalabs.org>
Date: Wed, 30 Jul 2025 10:26:13 -0400
Subject: [PATCH 08/26] Update vms/evm/metrics/prometheus/interfaces.go

Co-authored-by: Stephen Buttolph <stephen@avalabs.org>
Signed-off-by: Jonathan Oppenheimer <147infiniti@gmail.com>
---
 vms/evm/metrics/prometheus/interfaces.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/vms/evm/metrics/prometheus/interfaces.go b/vms/evm/metrics/prometheus/interfaces.go
index b8aa993453c0..dd5248281f9e 100644
--- a/vms/evm/metrics/prometheus/interfaces.go
+++ b/vms/evm/metrics/prometheus/interfaces.go
@@ -9,7 +9,7 @@ var _ Registry = metrics.Registry(nil)
 
 type Registry interface {
 	// Call the given function for each registered metric.
-	Each(func(string, any))
+	Each(func(name string, metric any))
 	// Get the metric by the given name or nil if none is registered.
 	Get(string) any
 }

From 32038aa3a3eca61e1f4ea0816f528bb08f9da8b0 Mon Sep 17 00:00:00 2001
From: Jonathan Oppenheimer <jonathan.oppenheimer@avalabs.org>
Date: Wed, 30 Jul 2025 10:26:32 -0400
Subject: [PATCH 09/26] Update vms/evm/metrics/prometheus/interfaces.go

Co-authored-by: Stephen Buttolph <stephen@avalabs.org>
Signed-off-by: Jonathan Oppenheimer <147infiniti@gmail.com>
---
 vms/evm/metrics/prometheus/interfaces.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/vms/evm/metrics/prometheus/interfaces.go b/vms/evm/metrics/prometheus/interfaces.go
index dd5248281f9e..4ddf117dd46a 100644
--- a/vms/evm/metrics/prometheus/interfaces.go
+++ b/vms/evm/metrics/prometheus/interfaces.go
@@ -11,5 +11,5 @@ type Registry interface {
 	// Call the given function for each registered metric.
 	Each(func(name string, metric any))
 	// Get the metric by the given name or nil if none is registered.
-	Get(string) any
+	Get(name string) any
 }

From 6e7fced1f551b6243b5034f8333632a4ffae6ad3 Mon Sep 17 00:00:00 2001
From: Jonathan Oppenheimer <jonathan.oppenheimer@avalabs.org>
Date: Wed, 30 Jul 2025 10:27:19 -0400
Subject: [PATCH 10/26] Update vms/evm/metrics/prometheus/prometheus.go

Co-authored-by: Stephen Buttolph <stephen@avalabs.org>
Signed-off-by: Jonathan Oppenheimer <147infiniti@gmail.com>
---
 vms/evm/metrics/prometheus/prometheus.go | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/vms/evm/metrics/prometheus/prometheus.go b/vms/evm/metrics/prometheus/prometheus.go
index 0745e90509d2..343142fa1afa 100644
--- a/vms/evm/metrics/prometheus/prometheus.go
+++ b/vms/evm/metrics/prometheus/prometheus.go
@@ -15,8 +15,8 @@ import (
 	dto "github.com/prometheus/client_model/go"
 )
 
-// Gatherer implements [prometheus.Gatherer] interface by
-// gathering all metrics from the given Prometheus registry.
+// Gatherer implements the [prometheus.Gatherer] interface by gathering all
+// metrics from a [Registry].
 type Gatherer struct {
 	registry Registry
 }

From 7179722df90b11d8e62889e5aa766a0dcc1fae5d Mon Sep 17 00:00:00 2001
From: Jonathan Oppenheimer <jonathan.oppenheimer@avalabs.org>
Date: Wed, 30 Jul 2025 10:28:14 -0400
Subject: [PATCH 11/26] Update vms/evm/metrics/prometheus/prometheus_test.go

Co-authored-by: Stephen Buttolph <stephen@avalabs.org>
Signed-off-by: Jonathan Oppenheimer <147infiniti@gmail.com>
---
 vms/evm/metrics/prometheus/prometheus_test.go | 37 +++++++------------
 1 file changed, 13 insertions(+), 24 deletions(-)

diff --git a/vms/evm/metrics/prometheus/prometheus_test.go b/vms/evm/metrics/prometheus/prometheus_test.go
index f4281a6af9ab..abe3acb6b5bd 100644
--- a/vms/evm/metrics/prometheus/prometheus_test.go
+++ b/vms/evm/metrics/prometheus/prometheus_test.go
@@ -143,28 +143,17 @@ func registerNilMetrics(t *testing.T, register func(t *testing.T, name string, c
 	// are disabled.
 	metrics.Enabled = false
 	defer func() { metrics.Enabled = true }()
-	nilCounter := metrics.NewCounter()
-	register(t, "nil/counter", nilCounter)
-	nilCounterFloat64 := metrics.NewCounterFloat64()
-	register(t, "nil/counter_float64", nilCounterFloat64)
-	nilEWMA := &metrics.NilEWMA{}
-	register(t, "nil/ewma", nilEWMA)
-	nilGauge := metrics.NewGauge()
-	register(t, "nil/gauge", nilGauge)
-	nilGaugeFloat64 := metrics.NewGaugeFloat64()
-	register(t, "nil/gauge_float64", nilGaugeFloat64)
-	nilGaugeInfo := metrics.NewGaugeInfo()
-	register(t, "nil/gauge_info", nilGaugeInfo)
-	nilHealthcheck := metrics.NewHealthcheck(nil)
-	register(t, "nil/healthcheck", nilHealthcheck)
-	nilHistogram := metrics.NewHistogram(nil)
-	register(t, "nil/histogram", nilHistogram)
-	nilMeter := metrics.NewMeter()
-	register(t, "nil/meter", nilMeter)
-	nilResettingTimer := metrics.NewResettingTimer()
-	register(t, "nil/resetting_timer", nilResettingTimer)
-	nilSample := metrics.NewUniformSample(1028)
-	register(t, "nil/sample", nilSample)
-	nilTimer := metrics.NewTimer()
-	register(t, "nil/timer", nilTimer)
+
+	register(t, "nil/counter", metrics.NewCounter())
+	register(t, "nil/counter_float64", metrics.NewCounterFloat64())
+	register(t, "nil/ewma", &metrics.NilEWMA{})
+	register(t, "nil/gauge", metrics.NewGauge())
+	register(t, "nil/gauge_float64", metrics.NewGaugeFloat64())
+	register(t, "nil/gauge_info", metrics.NewGaugeInfo())
+	register(t, "nil/healthcheck", metrics.NewHealthcheck(nil))
+	register(t, "nil/histogram", metrics.NewHistogram(nil))
+	register(t, "nil/meter", metrics.NewMeter())
+	register(t, "nil/resetting_timer", metrics.NewResettingTimer())
+	register(t, "nil/sample", metrics.NewUniformSample(1028))
+	register(t, "nil/timer", metrics.NewTimer())
 }

From 6af4cd133767412aa46c1844f6bdc52c43a1d234 Mon Sep 17 00:00:00 2001
From: Jonathan Oppenheimer <jonathan.oppenheimer@avalabs.org>
Date: Wed, 30 Jul 2025 10:28:38 -0400
Subject: [PATCH 12/26] Update vms/evm/metrics/prometheus/prometheus_test.go

Co-authored-by: Stephen Buttolph <stephen@avalabs.org>
Signed-off-by: Jonathan Oppenheimer <147infiniti@gmail.com>
---
 vms/evm/metrics/prometheus/prometheus_test.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/vms/evm/metrics/prometheus/prometheus_test.go b/vms/evm/metrics/prometheus/prometheus_test.go
index abe3acb6b5bd..36ddfa4e23fc 100644
--- a/vms/evm/metrics/prometheus/prometheus_test.go
+++ b/vms/evm/metrics/prometheus/prometheus_test.go
@@ -126,7 +126,7 @@ test_timer_count 6
 
 	require.Len(t, families, len(expectedMetrics))
 	for i, got := range families {
-		require.NotNil(t, *got.Name)
+		require.NotNil(t, got.Name)
 
 		want := expectedMetrics[*got.Name]
 		require.Equal(t, want, got, i)

From 739310ce84740a0546d51b2eadbbf0a3e06a8ad9 Mon Sep 17 00:00:00 2001
From: Jonathan Oppenheimer <jonathan.oppenheimer@avalabs.org>
Date: Wed, 30 Jul 2025 10:39:50 -0400
Subject: [PATCH 13/26] Maintain initial metrics.Enabled value

---
 vms/evm/metrics/metricstest/metrics.go | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/vms/evm/metrics/metricstest/metrics.go b/vms/evm/metrics/metricstest/metrics.go
index edd8a30ad29d..faf4d6686063 100644
--- a/vms/evm/metrics/metricstest/metrics.go
+++ b/vms/evm/metrics/metricstest/metrics.go
@@ -12,17 +12,19 @@ import (
 
 var metricsLock sync.Mutex
 
-// WithMetrics enables go-ethereum metrics globally for the test.
-// If the [metrics.Enabled] is already true, nothing is done.
-// Otherwise, it is set to true and is reverted to false when the test finishes.
+// WithMetrics enables [metrics.Enabled] for the test and prevents any other
+// tests with metrics from running concurrently.
+//
+// If [metrics.Enabled] is modified, its original value is restored as part of
+// the testing cleanup.
 func WithMetrics(t testing.TB) {
 	metricsLock.Lock()
 	t.Cleanup(metricsLock.Unlock)
-	if metrics.Enabled {
-		return
-	}
+	initialValue := metrics.Enabled
 	metrics.Enabled = true
+
+	// Restore the original value
 	t.Cleanup(func() {
-		metrics.Enabled = false
+		metrics.Enabled = initialValue
 	})
 }

From c90b0d6f5f40fd0d5d3bc461117ef98923663518 Mon Sep 17 00:00:00 2001
From: Jonathan Oppenheimer <jonathan.oppenheimer@avalabs.org>
Date: Wed, 30 Jul 2025 10:58:41 -0400
Subject: [PATCH 14/26] Prometheus variable organization

---
 vms/evm/metrics/prometheus/enabled_test.go | 10 +++---
 vms/evm/metrics/prometheus/prometheus.go   | 41 +++++++++-------------
 2 files changed, 22 insertions(+), 29 deletions(-)

diff --git a/vms/evm/metrics/prometheus/enabled_test.go b/vms/evm/metrics/prometheus/enabled_test.go
index 0f772a655b7a..8e32e365378e 100644
--- a/vms/evm/metrics/prometheus/enabled_test.go
+++ b/vms/evm/metrics/prometheus/enabled_test.go
@@ -7,14 +7,14 @@ import (
 	"testing"
 
 	"github.com/ava-labs/libevm/metrics"
-	// NOTE: This test assumes that there are no imported packages that might
-	// change the default value of [metrics.Enabled]. It is therefore in package
-	// `prometheus_test` in case any other tests modify the variable. If any
-	// imports here or in the implementation do actually do so then this test
-	// may have false negatives.
 	"github.com/stretchr/testify/require"
 )
 
+// This test assumes that there are no imported packages that might change the
+// default value of [metrics.Enabled]. It is therefore in package
+// `prometheus_test` in case any other tests modify the variable. If any imports
+// here or in the implementation do actually do so then this test may have false
+// negatives.
 func TestMetricsEnabledByDefault(t *testing.T) {
 	require.True(t, metrics.Enabled, "libevm/metrics.Enabled")
 	require.IsType(t, (*metrics.StandardCounter)(nil), metrics.NewCounter(), "metrics.NewCounter() returned wrong type")
diff --git a/vms/evm/metrics/prometheus/prometheus.go b/vms/evm/metrics/prometheus/prometheus.go
index 343142fa1afa..3c91569ba055 100644
--- a/vms/evm/metrics/prometheus/prometheus.go
+++ b/vms/evm/metrics/prometheus/prometheus.go
@@ -15,21 +15,21 @@ import (
 	dto "github.com/prometheus/client_model/go"
 )
 
+var (
+	_ prometheus.Gatherer = (*Gatherer)(nil)
+
+	errMetricSkip             = errors.New("metric skipped")
+	errMetricTypeNotSupported = errors.New("metric type is not supported")
+	quantiles                 = []float64{.5, .75, .95, .99, .999, .9999}
+	pvShortPercent            = []float64{50, 95, 99}
+)
+
 // Gatherer implements the [prometheus.Gatherer] interface by gathering all
 // metrics from a [Registry].
 type Gatherer struct {
 	registry Registry
 }
 
-var _ prometheus.Gatherer = (*Gatherer)(nil)
-
-// NewGatherer returns a [Gatherer] using the given registry.
-func NewGatherer(registry Registry) *Gatherer {
-	return &Gatherer{
-		registry: registry,
-	}
-}
-
 // Gather gathers metrics from the registry and converts them to
 // a slice of metric families.
 func (g *Gatherer) Gather() (mfs []*dto.MetricFamily, err error) {
@@ -55,12 +55,12 @@ func (g *Gatherer) Gather() (mfs []*dto.MetricFamily, err error) {
 	return mfs, nil
 }
 
-var (
-	errMetricSkip             = errors.New("metric skipped")
-	errMetricTypeNotSupported = errors.New("metric type is not supported")
-)
-
-func ptrTo[T any](x T) *T { return &x }
+// NewGatherer returns a [Gatherer] using the given registry.
+func NewGatherer(registry Registry) *Gatherer {
+	return &Gatherer{
+		registry: registry,
+	}
+}
 
 func metricFamily(registry Registry, name string) (mf *dto.MetricFamily, err error) {
 	metric := registry.Get(name)
@@ -116,8 +116,6 @@ func metricFamily(registry Registry, name string) (mf *dto.MetricFamily, err err
 		return nil, fmt.Errorf("%w: %q is a %T", errMetricSkip, name, m)
 	case metrics.Histogram:
 		snapshot := m.Snapshot()
-
-		quantiles := []float64{.5, .75, .95, .99, .999, .9999}
 		thresholds := snapshot.Percentiles(quantiles)
 		dtoQuantiles := make([]*dto.Quantile, len(quantiles))
 		for i := range thresholds {
@@ -126,7 +124,6 @@ func metricFamily(registry Registry, name string) (mf *dto.MetricFamily, err err
 				Value:    ptrTo(thresholds[i]),
 			}
 		}
-
 		return &dto.MetricFamily{
 			Name: &name,
 			Type: dto.MetricType_SUMMARY.Enum(),
@@ -150,8 +147,6 @@ func metricFamily(registry Registry, name string) (mf *dto.MetricFamily, err err
 		}, nil
 	case metrics.Timer:
 		snapshot := m.Snapshot()
-
-		quantiles := []float64{.5, .75, .95, .99, .999, .9999}
 		thresholds := snapshot.Percentiles(quantiles)
 		dtoQuantiles := make([]*dto.Quantile, len(quantiles))
 		for i := range thresholds {
@@ -160,7 +155,6 @@ func metricFamily(registry Registry, name string) (mf *dto.MetricFamily, err err
 				Value:    ptrTo(thresholds[i]),
 			}
 		}
-
 		return &dto.MetricFamily{
 			Name: &name,
 			Type: dto.MetricType_SUMMARY.Enum(),
@@ -178,8 +172,6 @@ func metricFamily(registry Registry, name string) (mf *dto.MetricFamily, err err
 		if count == 0 {
 			return nil, fmt.Errorf("%w: %q resetting timer metric count is zero", errMetricSkip, name)
 		}
-
-		pvShortPercent := []float64{50, 95, 99}
 		thresholds := snapshot.Percentiles(pvShortPercent)
 		dtoQuantiles := make([]*dto.Quantile, len(pvShortPercent))
 		for i := range pvShortPercent {
@@ -188,7 +180,6 @@ func metricFamily(registry Registry, name string) (mf *dto.MetricFamily, err err
 				Value:    ptrTo(thresholds[i]),
 			}
 		}
-
 		return &dto.MetricFamily{
 			Name: &name,
 			Type: dto.MetricType_SUMMARY.Enum(),
@@ -204,3 +195,5 @@ func metricFamily(registry Registry, name string) (mf *dto.MetricFamily, err err
 		return nil, fmt.Errorf("%w: metric %q type %T", errMetricTypeNotSupported, name, metric)
 	}
 }
+
+func ptrTo[T any](x T) *T { return &x }

From c6b8a185f7f7d8549575a4b3c2f5f915a75060ae Mon Sep 17 00:00:00 2001
From: Jonathan Oppenheimer <jonathan.oppenheimer@avalabs.org>
Date: Wed, 30 Jul 2025 11:10:35 -0400
Subject: [PATCH 15/26] Refactor vms/evm/metrics/prometheus/prometheus_test.go

---
 vms/evm/metrics/prometheus/prometheus_test.go | 136 ++++++++++--------
 1 file changed, 73 insertions(+), 63 deletions(-)

diff --git a/vms/evm/metrics/prometheus/prometheus_test.go b/vms/evm/metrics/prometheus/prometheus_test.go
index 36ddfa4e23fc..c518062be197 100644
--- a/vms/evm/metrics/prometheus/prometheus_test.go
+++ b/vms/evm/metrics/prometheus/prometheus_test.go
@@ -9,6 +9,7 @@ import (
 	"time"
 
 	"github.com/ava-labs/libevm/metrics"
+	dto "github.com/prometheus/client_model/go"
 	"github.com/prometheus/common/expfmt"
 	"github.com/stretchr/testify/require"
 
@@ -25,6 +26,78 @@ func TestGatherer_Gather(t *testing.T) {
 		require.NoErrorf(t, err, "registering collector %q", name)
 	}
 
+	registerNilMetrics(t, register)
+	registerRealMetrics(t, register)
+
+	gatherer := NewGatherer(registry)
+
+	families, err := gatherer.Gather()
+	require.NoError(t, err)
+
+	expectedMetrics := expectedMetrics(t)
+	require.Len(t, families, len(expectedMetrics))
+	for i, got := range families {
+		require.NotNil(t, got.Name)
+
+		want := expectedMetrics[*got.Name]
+		require.Equal(t, want, got, i)
+	}
+
+	register(t, "unsupported", metrics.NewHealthcheck(nil))
+	families, err = gatherer.Gather()
+	require.ErrorIs(t, err, errMetricTypeNotSupported)
+	require.Empty(t, families)
+}
+
+func expectedMetrics(t *testing.T) map[string]*dto.MetricFamily {
+	const expectedString = `
+		# TYPE test_counter counter
+		test_counter 12345
+		# TYPE test_counter_float64 counter
+		test_counter_float64 1.1
+		# TYPE test_gauge gauge
+		test_gauge 23456
+		# TYPE test_gauge_float64 gauge
+		test_gauge_float64 34567.89
+		# TYPE test_histogram summary
+		test_histogram{quantile="0.5"} 0
+		test_histogram{quantile="0.75"} 0
+		test_histogram{quantile="0.95"} 0
+		test_histogram{quantile="0.99"} 0
+		test_histogram{quantile="0.999"} 0
+		test_histogram{quantile="0.9999"} 0
+		test_histogram_sum 0
+		test_histogram_count 0
+		# TYPE test_meter gauge
+		test_meter 9.999999e+06
+		# TYPE test_resetting_timer summary
+		test_resetting_timer{quantile="50"} 1e+09
+		test_resetting_timer{quantile="95"} 1e+09
+		test_resetting_timer{quantile="99"} 1e+09
+		test_resetting_timer_sum 1e+09
+		test_resetting_timer_count 1
+		# TYPE test_timer summary
+		test_timer{quantile="0.5"} 2.25e+07
+		test_timer{quantile="0.75"} 4.8e+07
+		test_timer{quantile="0.95"} 1.2e+08
+		test_timer{quantile="0.99"} 1.2e+08
+		test_timer{quantile="0.999"} 1.2e+08
+		test_timer{quantile="0.9999"} 1.2e+08
+		test_timer_sum 2.3e+08
+		test_timer_count 6
+	`
+
+	var (
+		stringReader = strings.NewReader(expectedString)
+		parser       expfmt.TextParser
+	)
+
+	expectedMetrics, err := parser.TextToMetricFamilies(stringReader)
+	require.NoError(t, err)
+	return expectedMetrics
+}
+
+func registerRealMetrics(t *testing.T, register func(t *testing.T, name string, collector any)) {
 	counter := metrics.NewCounter()
 	counter.Inc(12345)
 	register(t, "test/counter", counter)
@@ -73,69 +146,6 @@ func TestGatherer_Gather(t *testing.T) {
 
 	emptyResettingTimer.Update(time.Second) // no effect because of snapshot below
 	register(t, "test/empty_resetting_timer_snapshot", emptyResettingTimer.Snapshot())
-
-	registerNilMetrics(t, register)
-
-	gatherer := NewGatherer(registry)
-
-	families, err := gatherer.Gather()
-	require.NoError(t, err)
-
-	const expectedString = `
-# TYPE test_counter counter
-test_counter 12345
-# TYPE test_counter_float64 counter
-test_counter_float64 1.1
-# TYPE test_gauge gauge
-test_gauge 23456
-# TYPE test_gauge_float64 gauge
-test_gauge_float64 34567.89
-# TYPE test_histogram summary
-test_histogram{quantile="0.5"} 0
-test_histogram{quantile="0.75"} 0
-test_histogram{quantile="0.95"} 0
-test_histogram{quantile="0.99"} 0
-test_histogram{quantile="0.999"} 0
-test_histogram{quantile="0.9999"} 0
-test_histogram_sum 0
-test_histogram_count 0
-# TYPE test_meter gauge
-test_meter 9.999999e+06
-# TYPE test_resetting_timer summary
-test_resetting_timer{quantile="50"} 1e+09
-test_resetting_timer{quantile="95"} 1e+09
-test_resetting_timer{quantile="99"} 1e+09
-test_resetting_timer_sum 1e+09
-test_resetting_timer_count 1
-# TYPE test_timer summary
-test_timer{quantile="0.5"} 2.25e+07
-test_timer{quantile="0.75"} 4.8e+07
-test_timer{quantile="0.95"} 1.2e+08
-test_timer{quantile="0.99"} 1.2e+08
-test_timer{quantile="0.999"} 1.2e+08
-test_timer{quantile="0.9999"} 1.2e+08
-test_timer_sum 2.3e+08
-test_timer_count 6
-`
-	var (
-		stringReader = strings.NewReader(expectedString)
-		parser       expfmt.TextParser
-	)
-	expectedMetrics, err := parser.TextToMetricFamilies(stringReader)
-	require.NoError(t, err)
-
-	require.Len(t, families, len(expectedMetrics))
-	for i, got := range families {
-		require.NotNil(t, got.Name)
-
-		want := expectedMetrics[*got.Name]
-		require.Equal(t, want, got, i)
-	}
-
-	register(t, "unsupported", metrics.NewHealthcheck(nil))
-	families, err = gatherer.Gather()
-	require.ErrorIs(t, err, errMetricTypeNotSupported)
-	require.Empty(t, families)
 }
 
 func registerNilMetrics(t *testing.T, register func(t *testing.T, name string, collector any)) {

From 0999f21b96b8c45ee974053d3f062c7a80b475c7 Mon Sep 17 00:00:00 2001
From: Jonathan Oppenheimer <jonathan.oppenheimer@avalabs.org>
Date: Wed, 30 Jul 2025 11:15:06 -0400
Subject: [PATCH 16/26] Accumulate errors in Gather()

---
 vms/evm/metrics/prometheus/prometheus.go | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/vms/evm/metrics/prometheus/prometheus.go b/vms/evm/metrics/prometheus/prometheus.go
index 3c91569ba055..6306c4328e12 100644
--- a/vms/evm/metrics/prometheus/prometheus.go
+++ b/vms/evm/metrics/prometheus/prometheus.go
@@ -35,6 +35,7 @@ type Gatherer struct {
 func (g *Gatherer) Gather() (mfs []*dto.MetricFamily, err error) {
 	// Gather and pre-sort the metrics to avoid random listings
 	var names []string
+	var errs []error
 	g.registry.Each(func(name string, _ any) {
 		names = append(names, name)
 	})
@@ -43,16 +44,17 @@ func (g *Gatherer) Gather() (mfs []*dto.MetricFamily, err error) {
 	mfs = make([]*dto.MetricFamily, 0, len(names))
 	for _, name := range names {
 		mf, err := metricFamily(g.registry, name)
+
 		switch {
 		case errors.Is(err, errMetricSkip):
 			continue
 		case err != nil:
-			return nil, err
+			errs = append(errs, err)
 		}
 		mfs = append(mfs, mf)
 	}
 
-	return mfs, nil
+	return mfs, errors.Join(errs...)
 }
 
 // NewGatherer returns a [Gatherer] using the given registry.

From 8af978f7ae09495e266b9f011e3eb010406d2f1b Mon Sep 17 00:00:00 2001
From: Jonathan Oppenheimer <jonathan.oppenheimer@avalabs.org>
Date: Thu, 31 Jul 2025 11:47:39 -0400
Subject: [PATCH 17/26] Proper import order

---
 vms/evm/metrics/prometheus/prometheus_test.go | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/vms/evm/metrics/prometheus/prometheus_test.go b/vms/evm/metrics/prometheus/prometheus_test.go
index c518062be197..afb2151b25ea 100644
--- a/vms/evm/metrics/prometheus/prometheus_test.go
+++ b/vms/evm/metrics/prometheus/prometheus_test.go
@@ -9,11 +9,12 @@ import (
 	"time"
 
 	"github.com/ava-labs/libevm/metrics"
-	dto "github.com/prometheus/client_model/go"
 	"github.com/prometheus/common/expfmt"
 	"github.com/stretchr/testify/require"
 
 	"github.com/ava-labs/avalanchego/vms/evm/metrics/metricstest"
+
+	dto "github.com/prometheus/client_model/go"
 )
 
 func TestGatherer_Gather(t *testing.T) {

From 83290c2350d8a5d3631ef44e5671f73e80635299 Mon Sep 17 00:00:00 2001
From: Jonathan Oppenheimer <jonathan.oppenheimer@avalabs.org>
Date: Thu, 31 Jul 2025 12:02:41 -0400
Subject: [PATCH 18/26] Add continue to swtich case

---
 vms/evm/metrics/prometheus/prometheus.go | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/vms/evm/metrics/prometheus/prometheus.go b/vms/evm/metrics/prometheus/prometheus.go
index 6306c4328e12..e37723ab417f 100644
--- a/vms/evm/metrics/prometheus/prometheus.go
+++ b/vms/evm/metrics/prometheus/prometheus.go
@@ -50,11 +50,15 @@ func (g *Gatherer) Gather() (mfs []*dto.MetricFamily, err error) {
 			continue
 		case err != nil:
 			errs = append(errs, err)
+			continue
 		}
 		mfs = append(mfs, mf)
 	}
 
-	return mfs, errors.Join(errs...)
+	if len(errs) > 0 {
+		return nil, errors.Join(errs...)
+	}
+	return mfs, nil
 }
 
 // NewGatherer returns a [Gatherer] using the given registry.

From 19d4194c4d39d2fa4e1905707f691ec39e63461e Mon Sep 17 00:00:00 2001
From: Jonathan Oppenheimer <jonathan.oppenheimer@avalabs.org>
Date: Thu, 31 Jul 2025 16:58:02 -0400
Subject: [PATCH 19/26] Update vms/evm/metrics/metricstest/metrics.go

Co-authored-by: Stephen Buttolph <stephen@avalabs.org>
Signed-off-by: Jonathan Oppenheimer <147infiniti@gmail.com>
---
 vms/evm/metrics/metricstest/metrics.go | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/vms/evm/metrics/metricstest/metrics.go b/vms/evm/metrics/metricstest/metrics.go
index faf4d6686063..0ec0dd2cfefd 100644
--- a/vms/evm/metrics/metricstest/metrics.go
+++ b/vms/evm/metrics/metricstest/metrics.go
@@ -15,8 +15,7 @@ var metricsLock sync.Mutex
 // WithMetrics enables [metrics.Enabled] for the test and prevents any other
 // tests with metrics from running concurrently.
 //
-// If [metrics.Enabled] is modified, its original value is restored as part of
-// the testing cleanup.
+// [metrics.Enabled] is restored to its original value during testing cleanup.
 func WithMetrics(t testing.TB) {
 	metricsLock.Lock()
 	t.Cleanup(metricsLock.Unlock)

From 8980eb1b22c70ac3960e767a6f04edcb8ecbb960 Mon Sep 17 00:00:00 2001
From: Jonathan Oppenheimer <jonathan.oppenheimer@avalabs.org>
Date: Thu, 31 Jul 2025 16:58:08 -0400
Subject: [PATCH 20/26] Update vms/evm/metrics/prometheus/prometheus.go

Co-authored-by: Stephen Buttolph <stephen@avalabs.org>
Signed-off-by: Jonathan Oppenheimer <147infiniti@gmail.com>
---
 vms/evm/metrics/prometheus/prometheus.go | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/vms/evm/metrics/prometheus/prometheus.go b/vms/evm/metrics/prometheus/prometheus.go
index e37723ab417f..fe216920a0fd 100644
--- a/vms/evm/metrics/prometheus/prometheus.go
+++ b/vms/evm/metrics/prometheus/prometheus.go
@@ -44,15 +44,12 @@ func (g *Gatherer) Gather() (mfs []*dto.MetricFamily, err error) {
 	mfs = make([]*dto.MetricFamily, 0, len(names))
 	for _, name := range names {
 		mf, err := metricFamily(g.registry, name)
-
 		switch {
-		case errors.Is(err, errMetricSkip):
-			continue
-		case err != nil:
+		case err == nil:
+			mfs = append(mfs, mf)
+		case !errors.Is(err, errMetricSkip):
 			errs = append(errs, err)
-			continue
 		}
-		mfs = append(mfs, mf)
 	}
 
 	if len(errs) > 0 {

From 2e5d18a0868e36d5c12368f349e56cdf545001c4 Mon Sep 17 00:00:00 2001
From: Jonathan Oppenheimer <jonathan.oppenheimer@avalabs.org>
Date: Thu, 31 Jul 2025 16:58:22 -0400
Subject: [PATCH 21/26] Update vms/evm/metrics/prometheus/prometheus.go

Co-authored-by: Stephen Buttolph <stephen@avalabs.org>
Signed-off-by: Jonathan Oppenheimer <147infiniti@gmail.com>
---
 vms/evm/metrics/prometheus/prometheus.go | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/vms/evm/metrics/prometheus/prometheus.go b/vms/evm/metrics/prometheus/prometheus.go
index fe216920a0fd..436df5f42c61 100644
--- a/vms/evm/metrics/prometheus/prometheus.go
+++ b/vms/evm/metrics/prometheus/prometheus.go
@@ -35,13 +35,15 @@ type Gatherer struct {
 func (g *Gatherer) Gather() (mfs []*dto.MetricFamily, err error) {
 	// Gather and pre-sort the metrics to avoid random listings
 	var names []string
-	var errs []error
 	g.registry.Each(func(name string, _ any) {
 		names = append(names, name)
 	})
 	slices.Sort(names)
 
-	mfs = make([]*dto.MetricFamily, 0, len(names))
+	var (
+		mfs = make([]*dto.MetricFamily, 0, len(names))
+		errs []error
+	)
 	for _, name := range names {
 		mf, err := metricFamily(g.registry, name)
 		switch {

From 149e8c286f2e62f93adbf5e5236378fc08e4a424 Mon Sep 17 00:00:00 2001
From: Jonathan Oppenheimer <jonathan.oppenheimer@avalabs.org>
Date: Thu, 31 Jul 2025 16:58:39 -0400
Subject: [PATCH 22/26] Update vms/evm/metrics/prometheus/prometheus.go

Co-authored-by: Stephen Buttolph <stephen@avalabs.org>
Signed-off-by: Jonathan Oppenheimer <147infiniti@gmail.com>
---
 vms/evm/metrics/prometheus/prometheus.go | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/vms/evm/metrics/prometheus/prometheus.go b/vms/evm/metrics/prometheus/prometheus.go
index 436df5f42c61..d88b5fb6298b 100644
--- a/vms/evm/metrics/prometheus/prometheus.go
+++ b/vms/evm/metrics/prometheus/prometheus.go
@@ -54,10 +54,7 @@ func (g *Gatherer) Gather() (mfs []*dto.MetricFamily, err error) {
 		}
 	}
 
-	if len(errs) > 0 {
-		return nil, errors.Join(errs...)
-	}
-	return mfs, nil
+	return mfs, errors.Join(errs...)
 }
 
 // NewGatherer returns a [Gatherer] using the given registry.

From 36b98e99ddfdfc907c15ff559b4e131b7e6f0f02 Mon Sep 17 00:00:00 2001
From: Jonathan Oppenheimer <jonathan.oppenheimer@avalabs.org>
Date: Thu, 31 Jul 2025 17:17:28 -0400
Subject: [PATCH 23/26] Fix TestGatherer_Gather test case

---
 vms/evm/metrics/prometheus/prometheus.go      |  5 +--
 vms/evm/metrics/prometheus/prometheus_test.go | 36 +++++++++++++++----
 2 files changed, 31 insertions(+), 10 deletions(-)

diff --git a/vms/evm/metrics/prometheus/prometheus.go b/vms/evm/metrics/prometheus/prometheus.go
index d88b5fb6298b..706485d0b990 100644
--- a/vms/evm/metrics/prometheus/prometheus.go
+++ b/vms/evm/metrics/prometheus/prometheus.go
@@ -40,10 +40,7 @@ func (g *Gatherer) Gather() (mfs []*dto.MetricFamily, err error) {
 	})
 	slices.Sort(names)
 
-	var (
-		mfs = make([]*dto.MetricFamily, 0, len(names))
-		errs []error
-	)
+	var errs []error
 	for _, name := range names {
 		mf, err := metricFamily(g.registry, name)
 		switch {
diff --git a/vms/evm/metrics/prometheus/prometheus_test.go b/vms/evm/metrics/prometheus/prometheus_test.go
index afb2151b25ea..47a9a5112062 100644
--- a/vms/evm/metrics/prometheus/prometheus_test.go
+++ b/vms/evm/metrics/prometheus/prometheus_test.go
@@ -32,22 +32,46 @@ func TestGatherer_Gather(t *testing.T) {
 
 	gatherer := NewGatherer(registry)
 
+	// Test successful gathering
 	families, err := gatherer.Gather()
 	require.NoError(t, err)
 
 	expectedMetrics := expectedMetrics(t)
-	require.Len(t, families, len(expectedMetrics))
-	for i, got := range families {
-		require.NotNil(t, got.Name)
 
-		want := expectedMetrics[*got.Name]
-		require.Equal(t, want, got, i)
+	require.Equal(t, len(expectedMetrics), len(families), "Expected %d metrics, got %d", len(expectedMetrics), len(families))
+
+	// Compare metrics by name since they're sorted alphabetically
+	for _, got := range families {
+		require.NotNil(t, got.Name)
+		want, exists := expectedMetrics[*got.Name]
+		require.True(t, exists, "unexpected metric: %s", *got.Name)
+		require.Equal(t, want, got, "metric: %s", *got.Name)
 	}
 
+	// Test gathering with unsupported metric type
 	register(t, "unsupported", metrics.NewHealthcheck(nil))
 	families, err = gatherer.Gather()
 	require.ErrorIs(t, err, errMetricTypeNotSupported)
-	require.Empty(t, families)
+
+	// When there's an error, we should still get the valid metrics that were gathered before the error
+	// ResettingTimer metrics reset after being read, so test_resetting_timer won't be included in
+	// subsequent Gather() calls
+	expectedMetricsWithoutResettingTimer := make(map[string]*dto.MetricFamily)
+	for name, metric := range expectedMetrics {
+		if name != "test_resetting_timer" {
+			expectedMetricsWithoutResettingTimer[name] = metric
+		}
+	}
+
+	require.Len(t, families, len(expectedMetricsWithoutResettingTimer))
+
+	// Compare metrics by name since they're sorted alphabetically
+	for _, got := range families {
+		require.NotNil(t, got.Name)
+		want, exists := expectedMetricsWithoutResettingTimer[*got.Name]
+		require.True(t, exists, "unexpected metric: %s", *got.Name)
+		require.Equal(t, want, got, "metric: %s", *got.Name)
+	}
 }
 
 func expectedMetrics(t *testing.T) map[string]*dto.MetricFamily {

From 0a4e60ac63a100242a95fff75bc03a445b7b62ca Mon Sep 17 00:00:00 2001
From: Jonathan Oppenheimer <jonathan.oppenheimer@avalabs.org>
Date: Thu, 31 Jul 2025 17:46:48 -0400
Subject: [PATCH 24/26] lint error

---
 vms/evm/metrics/prometheus/prometheus_test.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/vms/evm/metrics/prometheus/prometheus_test.go b/vms/evm/metrics/prometheus/prometheus_test.go
index 47a9a5112062..3259498ce5ba 100644
--- a/vms/evm/metrics/prometheus/prometheus_test.go
+++ b/vms/evm/metrics/prometheus/prometheus_test.go
@@ -38,7 +38,7 @@ func TestGatherer_Gather(t *testing.T) {
 
 	expectedMetrics := expectedMetrics(t)
 
-	require.Equal(t, len(expectedMetrics), len(families), "Expected %d metrics, got %d", len(expectedMetrics), len(families))
+	require.Len(t, families, len(expectedMetrics))
 
 	// Compare metrics by name since they're sorted alphabetically
 	for _, got := range families {

From 2ce2d42b7430697bce6734c30e58b98a8fd051d0 Mon Sep 17 00:00:00 2001
From: Stephen Buttolph <stephen@avalabs.org>
Date: Thu, 31 Jul 2025 18:38:37 -0400
Subject: [PATCH 25/26] Address final nits (#4148)

---
 vms/evm/metrics/metricstest/metrics.go        |   4 +-
 vms/evm/metrics/prometheus/prometheus.go      |   7 +-
 vms/evm/metrics/prometheus/prometheus_test.go | 135 +++++++-----------
 3 files changed, 55 insertions(+), 91 deletions(-)

diff --git a/vms/evm/metrics/metricstest/metrics.go b/vms/evm/metrics/metricstest/metrics.go
index 0ec0dd2cfefd..6d21ada56db5 100644
--- a/vms/evm/metrics/metricstest/metrics.go
+++ b/vms/evm/metrics/metricstest/metrics.go
@@ -18,12 +18,10 @@ var metricsLock sync.Mutex
 // [metrics.Enabled] is restored to its original value during testing cleanup.
 func WithMetrics(t testing.TB) {
 	metricsLock.Lock()
-	t.Cleanup(metricsLock.Unlock)
 	initialValue := metrics.Enabled
 	metrics.Enabled = true
-
-	// Restore the original value
 	t.Cleanup(func() {
 		metrics.Enabled = initialValue
+		metricsLock.Unlock()
 	})
 }
diff --git a/vms/evm/metrics/prometheus/prometheus.go b/vms/evm/metrics/prometheus/prometheus.go
index 706485d0b990..b3685607af05 100644
--- a/vms/evm/metrics/prometheus/prometheus.go
+++ b/vms/evm/metrics/prometheus/prometheus.go
@@ -32,7 +32,7 @@ type Gatherer struct {
 
 // Gather gathers metrics from the registry and converts them to
 // a slice of metric families.
-func (g *Gatherer) Gather() (mfs []*dto.MetricFamily, err error) {
+func (g *Gatherer) Gather() ([]*dto.MetricFamily, error) {
 	// Gather and pre-sort the metrics to avoid random listings
 	var names []string
 	g.registry.Each(func(name string, _ any) {
@@ -40,7 +40,10 @@ func (g *Gatherer) Gather() (mfs []*dto.MetricFamily, err error) {
 	})
 	slices.Sort(names)
 
-	var errs []error
+	var (
+		mfs  = make([]*dto.MetricFamily, 0, len(names))
+		errs []error
+	)
 	for _, name := range names {
 		mf, err := metricFamily(g.registry, name)
 		switch {
diff --git a/vms/evm/metrics/prometheus/prometheus_test.go b/vms/evm/metrics/prometheus/prometheus_test.go
index 3259498ce5ba..d29a02700289 100644
--- a/vms/evm/metrics/prometheus/prometheus_test.go
+++ b/vms/evm/metrics/prometheus/prometheus_test.go
@@ -9,14 +9,49 @@ import (
 	"time"
 
 	"github.com/ava-labs/libevm/metrics"
-	"github.com/prometheus/common/expfmt"
+	"github.com/prometheus/client_golang/prometheus/testutil"
 	"github.com/stretchr/testify/require"
 
 	"github.com/ava-labs/avalanchego/vms/evm/metrics/metricstest"
-
-	dto "github.com/prometheus/client_model/go"
 )
 
+const expectedMetrics = `
+	# TYPE test_counter counter
+	test_counter 12345
+	# TYPE test_counter_float64 counter
+	test_counter_float64 1.1
+	# TYPE test_gauge gauge
+	test_gauge 23456
+	# TYPE test_gauge_float64 gauge
+	test_gauge_float64 34567.89
+	# TYPE test_histogram summary
+	test_histogram{quantile="0.5"} 0
+	test_histogram{quantile="0.75"} 0
+	test_histogram{quantile="0.95"} 0
+	test_histogram{quantile="0.99"} 0
+	test_histogram{quantile="0.999"} 0
+	test_histogram{quantile="0.9999"} 0
+	test_histogram_sum 0
+	test_histogram_count 0
+	# TYPE test_meter gauge
+	test_meter 9.999999e+06
+	# TYPE test_resetting_timer summary
+	test_resetting_timer{quantile="50"} 1e+09
+	test_resetting_timer{quantile="95"} 1e+09
+	test_resetting_timer{quantile="99"} 1e+09
+	test_resetting_timer_sum 1e+09
+	test_resetting_timer_count 1
+	# TYPE test_timer summary
+	test_timer{quantile="0.5"} 2.25e+07
+	test_timer{quantile="0.75"} 4.8e+07
+	test_timer{quantile="0.95"} 1.2e+08
+	test_timer{quantile="0.99"} 1.2e+08
+	test_timer{quantile="0.999"} 1.2e+08
+	test_timer{quantile="0.9999"} 1.2e+08
+	test_timer_sum 2.3e+08
+	test_timer_count 6
+`
+
 func TestGatherer_Gather(t *testing.T) {
 	metricstest.WithMetrics(t)
 
@@ -32,94 +67,22 @@ func TestGatherer_Gather(t *testing.T) {
 
 	gatherer := NewGatherer(registry)
 
-	// Test successful gathering
-	families, err := gatherer.Gather()
-	require.NoError(t, err)
-
-	expectedMetrics := expectedMetrics(t)
+	// Test successful gathering.
+	//
+	// TODO: This results in resetting the timer, is this expected behavior?
+	require.NoError(t, testutil.GatherAndCompare(
+		gatherer,
+		strings.NewReader(expectedMetrics),
+	))
 
-	require.Len(t, families, len(expectedMetrics))
-
-	// Compare metrics by name since they're sorted alphabetically
-	for _, got := range families {
-		require.NotNil(t, got.Name)
-		want, exists := expectedMetrics[*got.Name]
-		require.True(t, exists, "unexpected metric: %s", *got.Name)
-		require.Equal(t, want, got, "metric: %s", *got.Name)
-	}
+	wantMetrics, err := gatherer.Gather()
+	require.NoError(t, err)
 
 	// Test gathering with unsupported metric type
 	register(t, "unsupported", metrics.NewHealthcheck(nil))
-	families, err = gatherer.Gather()
+	metrics, err := gatherer.Gather()
 	require.ErrorIs(t, err, errMetricTypeNotSupported)
-
-	// When there's an error, we should still get the valid metrics that were gathered before the error
-	// ResettingTimer metrics reset after being read, so test_resetting_timer won't be included in
-	// subsequent Gather() calls
-	expectedMetricsWithoutResettingTimer := make(map[string]*dto.MetricFamily)
-	for name, metric := range expectedMetrics {
-		if name != "test_resetting_timer" {
-			expectedMetricsWithoutResettingTimer[name] = metric
-		}
-	}
-
-	require.Len(t, families, len(expectedMetricsWithoutResettingTimer))
-
-	// Compare metrics by name since they're sorted alphabetically
-	for _, got := range families {
-		require.NotNil(t, got.Name)
-		want, exists := expectedMetricsWithoutResettingTimer[*got.Name]
-		require.True(t, exists, "unexpected metric: %s", *got.Name)
-		require.Equal(t, want, got, "metric: %s", *got.Name)
-	}
-}
-
-func expectedMetrics(t *testing.T) map[string]*dto.MetricFamily {
-	const expectedString = `
-		# TYPE test_counter counter
-		test_counter 12345
-		# TYPE test_counter_float64 counter
-		test_counter_float64 1.1
-		# TYPE test_gauge gauge
-		test_gauge 23456
-		# TYPE test_gauge_float64 gauge
-		test_gauge_float64 34567.89
-		# TYPE test_histogram summary
-		test_histogram{quantile="0.5"} 0
-		test_histogram{quantile="0.75"} 0
-		test_histogram{quantile="0.95"} 0
-		test_histogram{quantile="0.99"} 0
-		test_histogram{quantile="0.999"} 0
-		test_histogram{quantile="0.9999"} 0
-		test_histogram_sum 0
-		test_histogram_count 0
-		# TYPE test_meter gauge
-		test_meter 9.999999e+06
-		# TYPE test_resetting_timer summary
-		test_resetting_timer{quantile="50"} 1e+09
-		test_resetting_timer{quantile="95"} 1e+09
-		test_resetting_timer{quantile="99"} 1e+09
-		test_resetting_timer_sum 1e+09
-		test_resetting_timer_count 1
-		# TYPE test_timer summary
-		test_timer{quantile="0.5"} 2.25e+07
-		test_timer{quantile="0.75"} 4.8e+07
-		test_timer{quantile="0.95"} 1.2e+08
-		test_timer{quantile="0.99"} 1.2e+08
-		test_timer{quantile="0.999"} 1.2e+08
-		test_timer{quantile="0.9999"} 1.2e+08
-		test_timer_sum 2.3e+08
-		test_timer_count 6
-	`
-
-	var (
-		stringReader = strings.NewReader(expectedString)
-		parser       expfmt.TextParser
-	)
-
-	expectedMetrics, err := parser.TextToMetricFamilies(stringReader)
-	require.NoError(t, err)
-	return expectedMetrics
+	require.Equal(t, wantMetrics, metrics)
 }
 
 func registerRealMetrics(t *testing.T, register func(t *testing.T, name string, collector any)) {

From 22ea45039985b69ba13a2971761d213dc22c343c Mon Sep 17 00:00:00 2001
From: Stephen Buttolph <stephen@avalabs.org>
Date: Thu, 31 Jul 2025 18:50:46 -0400
Subject: [PATCH 26/26] Remove weird edge case

---
 vms/evm/metrics/prometheus/prometheus.go      | 5 +----
 vms/evm/metrics/prometheus/prometheus_test.go | 6 ++++++
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/vms/evm/metrics/prometheus/prometheus.go b/vms/evm/metrics/prometheus/prometheus.go
index b3685607af05..99b495f5ec01 100644
--- a/vms/evm/metrics/prometheus/prometheus.go
+++ b/vms/evm/metrics/prometheus/prometheus.go
@@ -170,10 +170,6 @@ func metricFamily(registry Registry, name string) (mf *dto.MetricFamily, err err
 		}, nil
 	case metrics.ResettingTimer:
 		snapshot := m.Snapshot()
-		count := snapshot.Count()
-		if count == 0 {
-			return nil, fmt.Errorf("%w: %q resetting timer metric count is zero", errMetricSkip, name)
-		}
 		thresholds := snapshot.Percentiles(pvShortPercent)
 		dtoQuantiles := make([]*dto.Quantile, len(pvShortPercent))
 		for i := range pvShortPercent {
@@ -182,6 +178,7 @@ func metricFamily(registry Registry, name string) (mf *dto.MetricFamily, err err
 				Value:    ptrTo(thresholds[i]),
 			}
 		}
+		count := snapshot.Count()
 		return &dto.MetricFamily{
 			Name: &name,
 			Type: dto.MetricType_SUMMARY.Enum(),
diff --git a/vms/evm/metrics/prometheus/prometheus_test.go b/vms/evm/metrics/prometheus/prometheus_test.go
index d29a02700289..8b65a5c3606c 100644
--- a/vms/evm/metrics/prometheus/prometheus_test.go
+++ b/vms/evm/metrics/prometheus/prometheus_test.go
@@ -20,6 +20,12 @@ const expectedMetrics = `
 	test_counter 12345
 	# TYPE test_counter_float64 counter
 	test_counter_float64 1.1
+	# TYPE test_empty_resetting_timer summary
+	test_empty_resetting_timer{quantile="50"} 0
+	test_empty_resetting_timer{quantile="95"} 0
+	test_empty_resetting_timer{quantile="99"} 0
+	test_empty_resetting_timer_sum 0
+	test_empty_resetting_timer_count 0
 	# TYPE test_gauge gauge
 	test_gauge 23456
 	# TYPE test_gauge_float64 gauge