Updated the Probe method in the Persistence package with a query deadline.

Packages/Persistence/Tests/Cases/Public/Methods/ProbeTests.swift

@@ -57,6 +57,46 @@ struct ProbeTests {
         #expect(!isReachable)
     }
 
+    @Test
+    func `reports a hanging database as unreachable within its timeout`() async throws {
+        // The silent server accepts the TCP connection and never answers, so the probe's query can only
+        // ever be resolved by its deadline — without one, it would wait out the driver's own connect
+        // timeout (10 seconds) instead.
+        let server = try await SilentPostgresServer.start()
+        let service = try Service(
+            driver: .postgres(
+                .init(
+                    host: "127.0.0.1",
+                    port: server.port,
+                    name: "hanging",
+                    username: "nobody",
+                    password: "nothing",
+                    tls: .off,
+                    maxConnectionsPerEventLoop: 1
+                )
+            ),
+            logger: Logger(label: "test")
+        )
+        let fluent = service()
+        let probe = Probe(
+            fluent: fluent,
+            timeout: .milliseconds(100)
+        )
+
+        let clock = ContinuousClock()
+        let start = clock.now
+        let isReachable = await probe()
+        let elapsed = clock.now - start
+
+        try await fluent.shutdown()
+        try await server.stop()
+
+        #expect(!isReachable)
+        // Well past the 100-millisecond deadline to absorb scheduling noise, yet far below the driver's
+        // 10-second connect timeout — only the deadline can answer this fast.
+        #expect(elapsed < .seconds(5))
+    }
+
     @Test
     func `reports a default database that is not an SQL database`() async throws {
         let fluent = Fluent(logger: Logger(label: "test"))

Packages/Persistence/Tests/Utils/Fakes/SilentPostgresServer.swift

@@ -0,0 +1,54 @@
+import NIOCore
+import NIOPosix
+
+/// A fake server accepting connections and never answering.
+///
+/// A client connecting to it completes the TCP handshake and then waits forever for the first protocol byte — the shape of a database that hangs rather
+/// than refuses. This is what the probe's deadline test connects to, proving the probe answers within its timeout instead of hanging alongside the server.
+final class SilentPostgresServer {
+
+    // MARK: Properties
+
+    /// The port the server listens on, assigned by the system at bind time.
+    let port: Int
+
+    /// The listening channel the server accepts connections through.
+    private let channel: Channel
+
+    // MARK: Initializers
+
+    private init(
+        channel: Channel,
+        port: Int
+    ) {
+        self.channel = channel
+        self.port = port
+    }
+
+    // MARK: Functions
+
+    /// Starts a server on the loopback interface, on a system-assigned port.
+    /// - Returns: the running server, ready to be connected to at ``port``.
+    static func start() async throws -> SilentPostgresServer {
+        let channel = try await ServerBootstrap(group: MultiThreadedEventLoopGroup.singleton)
+            .bind(host: "127.0.0.1", port: 0)
+            .get()
+
+        guard let port = channel.localAddress?.port else {
+            throw ChannelError.unknownLocalAddress
+        }
+
+        return .init(
+            channel: channel,
+            port: port
+        )
+    }
+
+    /// Stops the server, closing its listening channel.
+    func stop() async throws {
+        try await channel
+            .close()
+            .get()
+    }
+
+}