fix: correct native histogram bucket merge on scale-down

.github/workflows/acceptance-tests.yml

@@ -15,7 +15,7 @@ jobs:
         uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7
       - uses: jdx/mise-action@e6a8b3978addb5a52f2b4cd9d91eafa7f0ab959d # v4.2.0
         with:
-          version: v2026.6.14
-          sha256: 96ae1ef7b00a6ebbbec23ba1016d6e722f5e904966272f621d15326429e90d53
+          version: v2026.7.0
+          sha256: 0744cb3c303baf0d308ff7b112ed41f22abb6029cb5644fd3a8ce74b29f16a68
       - name: Run acceptance tests
         run: mise run acceptance-test

.github/workflows/api-diff.yml

@@ -34,8 +34,8 @@ jobs:
           persist-credentials: false
       - uses: jdx/mise-action@e6a8b3978addb5a52f2b4cd9d91eafa7f0ab959d # v4.2.0
         with:
-          version: v2026.6.14
-          sha256: 96ae1ef7b00a6ebbbec23ba1016d6e722f5e904966272f621d15326429e90d53
+          version: v2026.7.0
+          sha256: 0744cb3c303baf0d308ff7b112ed41f22abb6029cb5644fd3a8ce74b29f16a68
       - name: Cache local Maven repository
         uses: actions/cache@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0
         with:

.github/workflows/build.yml

@@ -14,8 +14,8 @@ jobs:
           persist-credentials: false
       - uses: jdx/mise-action@e6a8b3978addb5a52f2b4cd9d91eafa7f0ab959d # v4.2.0
         with:
-          version: v2026.6.14
-          sha256: 96ae1ef7b00a6ebbbec23ba1016d6e722f5e904966272f621d15326429e90d53
+          version: v2026.7.0
+          sha256: 0744cb3c303baf0d308ff7b112ed41f22abb6029cb5644fd3a8ce74b29f16a68
       - name: Cache local Maven repository
         uses: actions/cache@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0
         with:

.github/workflows/bump-api-diff-baseline.yml

@@ -35,8 +35,8 @@ jobs:
           persist-credentials: true
       - uses: jdx/mise-action@e6a8b3978addb5a52f2b4cd9d91eafa7f0ab959d # v4.2.0
         with:
-          version: v2026.6.14
-          sha256: 96ae1ef7b00a6ebbbec23ba1016d6e722f5e904966272f621d15326429e90d53
+          version: v2026.7.0
+          sha256: 0744cb3c303baf0d308ff7b112ed41f22abb6029cb5644fd3a8ce74b29f16a68
       - name: Cache local Maven repository
         uses: actions/cache@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0
         with:

.github/workflows/generate-protobuf.yml

@@ -20,8 +20,8 @@ jobs:
           persist-credentials: false
       - uses: jdx/mise-action@e6a8b3978addb5a52f2b4cd9d91eafa7f0ab959d # v4.2.0
         with:
-          version: v2026.6.14
-          sha256: 96ae1ef7b00a6ebbbec23ba1016d6e722f5e904966272f621d15326429e90d53
+          version: v2026.7.0
+          sha256: 0744cb3c303baf0d308ff7b112ed41f22abb6029cb5644fd3a8ce74b29f16a68
       - name: Cache local Maven repository
         uses: actions/cache@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0
         with:

.github/workflows/github-pages.yaml

@@ -39,8 +39,8 @@ jobs:
           fetch-depth: 0
       - uses: jdx/mise-action@e6a8b3978addb5a52f2b4cd9d91eafa7f0ab959d # v4.2.0
         with:
-          version: v2026.6.14
-          sha256: 96ae1ef7b00a6ebbbec23ba1016d6e722f5e904966272f621d15326429e90d53
+          version: v2026.7.0
+          sha256: 0744cb3c303baf0d308ff7b112ed41f22abb6029cb5644fd3a8ce74b29f16a68
           cache: "false"
       - name: Setup Pages
         id: pages

.github/workflows/java-version-matrix-tests.yml

@@ -33,8 +33,8 @@ jobs:
       - name: Set up mise
         uses: jdx/mise-action@e6a8b3978addb5a52f2b4cd9d91eafa7f0ab959d # v4.2.0
         with:
-          version: v2026.6.14
-          sha256: 96ae1ef7b00a6ebbbec23ba1016d6e722f5e904966272f621d15326429e90d53
+          version: v2026.7.0
+          sha256: 0744cb3c303baf0d308ff7b112ed41f22abb6029cb5644fd3a8ce74b29f16a68
 
       - name: Cache local Maven repository
         uses: actions/cache@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0

.github/workflows/jmx-exporter-compatibility.yml

@@ -24,8 +24,8 @@ jobs:
           persist-credentials: false
       - uses: jdx/mise-action@e6a8b3978addb5a52f2b4cd9d91eafa7f0ab959d # v4.2.0
         with:
-          version: v2026.6.14
-          sha256: 96ae1ef7b00a6ebbbec23ba1016d6e722f5e904966272f621d15326429e90d53
+          version: v2026.7.0
+          sha256: 0744cb3c303baf0d308ff7b112ed41f22abb6029cb5644fd3a8ce74b29f16a68
           working_directory: .mise/envs/jmx-exporter
       - name: Cache local Maven repository
         uses: actions/cache@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0

.github/workflows/lint.yml

@@ -23,8 +23,8 @@ jobs:
       - name: Setup mise
         uses: jdx/mise-action@e6a8b3978addb5a52f2b4cd9d91eafa7f0ab959d # v4.2.0
         with:
-          version: v2026.6.14
-          sha256: 96ae1ef7b00a6ebbbec23ba1016d6e722f5e904966272f621d15326429e90d53
+          version: v2026.7.0
+          sha256: 0744cb3c303baf0d308ff7b112ed41f22abb6029cb5644fd3a8ce74b29f16a68
 
       - name: Lint
         env:

.github/workflows/micrometer-compatibility.yml

@@ -32,8 +32,8 @@ jobs:
           persist-credentials: false
       - uses: jdx/mise-action@e6a8b3978addb5a52f2b4cd9d91eafa7f0ab959d # v4.2.0
         with:
-          version: v2026.6.14
-          sha256: 96ae1ef7b00a6ebbbec23ba1016d6e722f5e904966272f621d15326429e90d53
+          version: v2026.7.0
+          sha256: 0744cb3c303baf0d308ff7b112ed41f22abb6029cb5644fd3a8ce74b29f16a68
           working_directory: .mise/envs/micrometer
       - name: Cache local Maven repository
         uses: actions/cache@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0

.github/workflows/native-tests.yml

@@ -15,8 +15,8 @@ jobs:
         uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7
       - uses: jdx/mise-action@e6a8b3978addb5a52f2b4cd9d91eafa7f0ab959d # v4.2.0
         with:
-          version: v2026.6.14
-          sha256: 96ae1ef7b00a6ebbbec23ba1016d6e722f5e904966272f621d15326429e90d53
+          version: v2026.7.0
+          sha256: 0744cb3c303baf0d308ff7b112ed41f22abb6029cb5644fd3a8ce74b29f16a68
           working_directory: .mise/envs/native
       - name: Run native tests
         working-directory: .mise/envs/native

.github/workflows/nightly-benchmarks.yml

@@ -36,8 +36,8 @@ jobs:
       - name: Setup mise
         uses: jdx/mise-action@e6a8b3978addb5a52f2b4cd9d91eafa7f0ab959d # v4.2.0
         with:
-          version: v2026.6.14
-          sha256: 96ae1ef7b00a6ebbbec23ba1016d6e722f5e904966272f621d15326429e90d53
+          version: v2026.7.0
+          sha256: 0744cb3c303baf0d308ff7b112ed41f22abb6029cb5644fd3a8ce74b29f16a68
 
       - name: Cache local Maven repository
         uses: actions/cache@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0

.github/workflows/regenerate-api-diff-otel.yml

@@ -20,8 +20,8 @@ jobs:
           persist-credentials: false
       - uses: jdx/mise-action@e6a8b3978addb5a52f2b4cd9d91eafa7f0ab959d # v4.2.0
         with:
-          version: v2026.6.14
-          sha256: 96ae1ef7b00a6ebbbec23ba1016d6e722f5e904966272f621d15326429e90d53
+          version: v2026.7.0
+          sha256: 0744cb3c303baf0d308ff7b112ed41f22abb6029cb5644fd3a8ce74b29f16a68
       - name: Cache local Maven repository
         uses: actions/cache@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0
         with:

.github/workflows/release.yml

@@ -71,8 +71,8 @@ jobs:
 
       - uses: jdx/mise-action@e6a8b3978addb5a52f2b4cd9d91eafa7f0ab959d # v4.2.0
         with:
-          version: v2026.6.14
-          sha256: 96ae1ef7b00a6ebbbec23ba1016d6e722f5e904966272f621d15326429e90d53
+          version: v2026.7.0
+          sha256: 0744cb3c303baf0d308ff7b112ed41f22abb6029cb5644fd3a8ce74b29f16a68
           cache: false
 
       - name: Build release version

.github/workflows/test-release-build.yml

@@ -20,8 +20,8 @@ jobs:
           fetch-depth: 0
       - uses: jdx/mise-action@e6a8b3978addb5a52f2b4cd9d91eafa7f0ab959d # v4.2.0
         with:
-          version: v2026.6.14
-          sha256: 96ae1ef7b00a6ebbbec23ba1016d6e722f5e904966272f621d15326429e90d53
+          version: v2026.7.0
+          sha256: 0744cb3c303baf0d308ff7b112ed41f22abb6029cb5644fd3a8ce74b29f16a68
       - name: Cache local Maven repository
         uses: actions/cache@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0
         with:

prometheus-metrics-core/src/main/java/io/prometheus/metrics/core/metrics/Histogram.java

@@ -614,7 +614,7 @@ private void doubleBucketWidth(Map<Integer, LongAdder> buckets) {
       }
       buckets.clear();
       for (i = 0; i < keys.length; i++) {
-        int index = (keys[i] + 1) / 2;
+        int index = (keys[i] > 0 ? keys[i] + 1 : keys[i]) / 2;
         LongAdder count = buckets.computeIfAbsent(index, k -> new LongAdder());
         count.add(values[i]);
       }

prometheus-metrics-core/src/test/java/io/prometheus/metrics/core/metrics/HistogramTest.java

@@ -28,7 +28,9 @@
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.Comparator;
+import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
 import java.util.Random;
 import java.util.concurrent.CompletionService;
 import java.util.concurrent.CountDownLatch;
@@ -39,6 +41,7 @@
 import java.util.concurrent.Future;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
+import java.util.concurrent.atomic.LongAdder;
 import java.util.stream.Collectors;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
@@ -836,6 +839,36 @@ void testNativeBucketIndexToUpperBound()
     }
   }
 
+  @Test
+  void testDoubleBucketWidthMergesNegativeIndexesCorrectly()
+      throws NoSuchMethodException, InvocationTargetException, IllegalAccessException {
+    Histogram histogram = Histogram.builder().name("test").nativeOnly().build();
+    Histogram.DataPoint dataPoint = histogram.newDataPoint();
+
+    Method doubleBucketWidth =
+        Histogram.DataPoint.class.getDeclaredMethod("doubleBucketWidth", Map.class);
+    doubleBucketWidth.setAccessible(true);
+
+    int[] keys = {-5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5};
+    int[] expectedMergedIndexes = {-2, -2, -1, -1, 0, 0, 1, 1, 2, 2, 3};
+
+    for (int i = 0; i < keys.length; i++) {
+      Map<Integer, LongAdder> buckets = new HashMap<>();
+      LongAdder adder = new LongAdder();
+      adder.add(7);
+      buckets.put(keys[i], adder);
+
+      doubleBucketWidth.invoke(dataPoint, buckets);
+
+      assertThat(buckets.keySet())
+          .as("merged index for original key " + keys[i])
+          .containsExactly(expectedMergedIndexes[i]);
+      assertThat(buckets.get(expectedMergedIndexes[i]).sum())
+          .as("count preserved for original key " + keys[i])
+          .isEqualTo(7);
+    }
+  }
+
   /**
    * Test if lowerBound < value <= upperBound is true for the bucket index returned by
    * findBucketIndex()