diff --git a/CHANGELOG.md b/CHANGELOG.md
index bd4feaa..e048d71 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,15 @@ All notable changes to `detain/phlix-shared` are documented here.
 
 This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [0.10.1] - 2026-06-23
+
+### Added
+- **`ServerInfoDto.libraryCount`** (optional `?int`, default `null`) — the number of
+  libraries a server last reported via heartbeat (from the hub's `server_libraries`
+  cache). Round-trips through `fromPayload()`/`toPayload()`; absent/null tolerated so
+  older payloads keep working. Lets the hub's "My Servers" UI show a real library
+  count instead of "—".
+
 ## [0.10.0] - 2026-06-23
 
 ### Added
diff --git a/src/Hub/ServerInfoDto.php b/src/Hub/ServerInfoDto.php
index e0e2697..2488c3b 100644
--- a/src/Hub/ServerInfoDto.php
+++ b/src/Hub/ServerInfoDto.php
@@ -29,6 +29,9 @@ final class ServerInfoDto
      * @param string         $status             One of self::STATUS_*.
      * @param list<string>   $hostnameCandidates Last known reachable hostnames.
      * @param bool           $relayActive        Whether a WSS reverse tunnel is currently open (Phase C.6).
+     * @param int|null       $libraryCount       Number of libraries the server last reported via heartbeat
+     *                                            (from the hub's `server_libraries` cache). Null when the
+     *                                            server has not reported any yet (older servers / pre-heartbeat).
      */
     public function __construct(
         public readonly string $serverId,
@@ -39,6 +42,7 @@ public function __construct(
         public readonly string $status,
         public readonly array $hostnameCandidates,
         public readonly bool $relayActive,
+        public readonly ?int $libraryCount = null,
     ) {
     }
 
@@ -80,6 +84,14 @@ public static function fromPayload(array $payload): self
             throw new InvalidArgumentException('ServerInfoDto "relayActive" must be a boolean.');
         }
 
+        $libraryCount = null;
+        if (array_key_exists('libraryCount', $payload) && $payload['libraryCount'] !== null) {
+            if (!is_int($payload['libraryCount'])) {
+                throw new InvalidArgumentException('ServerInfoDto "libraryCount" must be an integer when present.');
+            }
+            $libraryCount = $payload['libraryCount'];
+        }
+
         return new self(
             serverId: $serverId,
             userId: $userId,
@@ -89,6 +101,7 @@ public static function fromPayload(array $payload): self
             status: $status,
             hostnameCandidates: $hostnameCandidates,
             relayActive: $payload['relayActive'],
+            libraryCount: $libraryCount,
         );
     }
 
@@ -106,6 +119,7 @@ public function toPayload(): array
             'status' => $this->status,
             'hostnameCandidates' => $this->hostnameCandidates,
             'relayActive' => $this->relayActive,
+            'libraryCount' => $this->libraryCount,
         ];
     }
 
diff --git a/src/Version.php b/src/Version.php
index d9e8c84..7193d1a 100644
--- a/src/Version.php
+++ b/src/Version.php
@@ -24,7 +24,7 @@ final class Version
      *
      * @var non-empty-string
      */
-    public const VERSION = '0.10.0';
+    public const VERSION = '0.10.1';
 
     /**
      * Prevent instantiation — static marker only.
diff --git a/tests/Hub/ServerInfoDtoTest.php b/tests/Hub/ServerInfoDtoTest.php
index facb797..b58ae28 100644
--- a/tests/Hub/ServerInfoDtoTest.php
+++ b/tests/Hub/ServerInfoDtoTest.php
@@ -27,6 +27,7 @@ private static function full(): array
             'status' => ServerInfoDto::STATUS_ONLINE,
             'hostnameCandidates' => ['10.0.0.5'],
             'relayActive' => true,
+            'libraryCount' => 7,
         ];
     }
 
@@ -34,6 +35,26 @@ public function test_round_trip(): void
     {
         $dto = ServerInfoDto::fromPayload(self::full());
         $this->assertSame(self::full(), $dto->toPayload());
+        $this->assertSame(7, $dto->libraryCount);
+    }
+
+    public function test_libraryCount_absent_defaults_to_null(): void
+    {
+        $payload = self::full();
+        unset($payload['libraryCount']);
+        $dto = ServerInfoDto::fromPayload($payload);
+        $this->assertNull($dto->libraryCount);
+        $this->assertNull($dto->toPayload()['libraryCount']);
+    }
+
+    public function test_non_int_libraryCount_throws(): void
+    {
+        $payload = self::full();
+        $payload['libraryCount'] = 'lots';
+
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage('libraryCount');
+        ServerInfoDto::fromPayload($payload);
     }
 
     public function test_lastSeenAt_null_round_trip(): void