diff --git a/src/Panel/Dump/DumpCardRenderer.php b/src/Panel/Dump/DumpCardRenderer.php
index b8a12a8..25bf026 100644
--- a/src/Panel/Dump/DumpCardRenderer.php
+++ b/src/Panel/Dump/DumpCardRenderer.php
@@ -80,7 +80,9 @@ private static function firstFrame(array $trace): array
     }
 
     /**
-     * Formats a Unix timestamp in seconds as `H:i:s.mmm`, falling back to `''` when no timestamp is set.
+     * Formats the row timestamp as `H:i:s.mmm`, falling back to `''` when no timestamp is set.
+     *
+     * {@see DumpRow::$time} already holds epoch milliseconds, so the fraction is truncated, not scaled again.
      */
     private static function formatTime(float $time): string
     {
@@ -88,7 +90,7 @@ private static function formatTime(float $time): string
             return '';
         }
 
-        return Format::timeOfDay(intval($time * 1000));
+        return Format::timeOfDay(intval($time));
     }
 
     /**
diff --git a/tests/Panel/Dump/DumpCardRendererTest.php b/tests/Panel/Dump/DumpCardRendererTest.php
index 43b473e..8ba7634 100644
--- a/tests/Panel/Dump/DumpCardRendererTest.php
+++ b/tests/Panel/Dump/DumpCardRendererTest.php
@@ -146,7 +146,7 @@ public function testRenderMessageCellEscapesMalformedAndMismatchedDumpTags(): vo
     public function testRenderMessageCellFormatsMillisecondsAtTheUpperBoundary(): void
     {
         $html = DumpCardRenderer::renderMessageCell(
-            self::makeRow(time: 1_700_000_000.1239),
+            self::makeRow(time: 1_700_000_000_123.9),
             self::traceLine(),
             0,
         );
@@ -162,7 +162,7 @@ public function testRenderMessageCellFormatsMillisecondsAtTheUpperBoundary(): vo
             </div>
             HTML,
             $html,
-            'Millisecond conversion must use exactly one thousand units per second.',
+            'Fractional milliseconds must be truncated, not scaled.',
         );
     }
 
@@ -211,7 +211,7 @@ public function testRenderMessageCellKeepsPollutedClosingTokensEscaped(): void
     public function testRenderMessageCellKeepsTimeAndTraceMetadataTogether(): void
     {
         $html = DumpCardRenderer::renderMessageCell(
-            self::makeRow(time: 1_700_000_000.5, trace: [['file' => '/app/User.php', 'line' => 42]]),
+            self::makeRow(time: 1_700_000_000_500.0, trace: [['file' => '/app/User.php', 'line' => 42]]),
             self::traceLine(),
             0,
         );
@@ -418,7 +418,7 @@ public function testRenderMessageCellOmitsTypeBadgeWhenPayloadStartsWithSymbol()
     public function testRenderMessageCellRendersFormattedTimeWhenTimeIsPositive(): void
     {
         $html = DumpCardRenderer::renderMessageCell(
-            self::makeRow(time: 1_700_000_000.789),
+            self::makeRow(time: 1_700_000_000_789.0),
             self::traceLine(),
             0,
         );
diff --git a/tests/Storage/SnapshotStoreTest.php b/tests/Storage/SnapshotStoreTest.php
index 25b171c..4d5de94 100644
--- a/tests/Storage/SnapshotStoreTest.php
+++ b/tests/Storage/SnapshotStoreTest.php
@@ -5,7 +5,7 @@
 namespace PHPForge\Debug\Tests\Storage;
 
 use PHPForge\Debug\Storage\{DebugSnapshot, RequestSummary, SnapshotStore, StorageException};
-use PHPUnit\Framework\Attributes\{Group, TestWith};
+use PHPUnit\Framework\Attributes\{Group, RequiresOperatingSystemFamily, TestWith};
 use PHPUnit\Framework\TestCase;
 use Xepozz\InternalMocker\MockerState;
 
@@ -485,12 +485,9 @@ public function testManifestReadResultDistinguishesEmptyStoreFromCorruptManifest
         );
     }
 
+    #[RequiresOperatingSystemFamily('Linux')]
     public function testManifestReadResultReportsEmptyAndUnreadableManifestFiles(): void
     {
-        if (PHP_OS_FAMILY === 'Windows') {
-            self::markTestSkipped('POSIX read permissions are not portable to Windows.');
-        }
-
         mkdir($this->path, recursive: true);
         file_put_contents("{$this->path}/index.json", '');
 
@@ -902,12 +899,9 @@ public function testSnapshotReadResultDistinguishesMissingInvalidAndCorruptSnaps
         );
     }
 
+    #[RequiresOperatingSystemFamily('Linux')]
     public function testSnapshotReadResultReportsEmptyMismatchAndUnreadableFiles(): void
     {
-        if (PHP_OS_FAMILY === 'Windows') {
-            self::markTestSkipped('POSIX read permissions are not portable to Windows.');
-        }
-
         mkdir($this->path, recursive: true);
         file_put_contents("{$this->path}/empty.json", '');
 
@@ -1513,12 +1507,9 @@ static function (string $directory, string $prefix) use (&$temporaryFileCalls):
         );
     }
 
+    #[RequiresOperatingSystemFamily('Linux')]
     public function testWriteRejectsUnreadableExistingTransactionTarget(): void
     {
-        if (PHP_OS_FAMILY === 'Windows') {
-            self::markTestSkipped('POSIX read permissions are not portable to Windows.');
-        }
-
         $store = $this->store();
 
         $store->writeSnapshot(
@@ -1539,14 +1530,9 @@ public function testWriteRejectsUnreadableExistingTransactionTarget(): void
         );
     }
 
+    #[RequiresOperatingSystemFamily('Linux')]
     public function testWriteRejectsUnreadableManifest(): void
     {
-        if (PHP_OS_FAMILY === 'Windows') {
-            self::markTestSkipped(
-                'POSIX read permissions are not portable to Windows.',
-            );
-        }
-
         $store = $this->store();
 
         $store->writeSnapshot(