feat(discovery): recognise the headless X32Link (ESP-035)

Sources/KitchenSyncApp/Discovery/DeviceMatch.swift

@@ -30,11 +30,16 @@ enum DeviceMatch {
     /// units working, not because it is correct.
     ///
     /// The firmware advertises generic `_http._tcp` with no TXT record, so the hostname is all a
-    /// client has. `ks_hostname()` builds `<product>-<last two MAC bytes>`: `kitchensync-a4f2` on
-    /// the P4, `kstouch-dfd0` on the Touch. Missing `kstouch` is what made a real device invisible.
+    /// client has. The hostname is `<product>-<last two MAC bytes>`: `kitchensync-a4f2` on the
+    /// P4, `kstouch-dfd0` on the Touch, `x32link-7a1c` on the headless (ESP-035). Missing
+    /// `kstouch` is what made a real device invisible once already.
     private static func matchesKnownHostname(_ name: String) -> Bool {
         knownHostPrefixes.contains { name.hasPrefix($0) }
     }
 
-    private static let knownHostPrefixes = ["kitchensync", "kstouch"]
+    /// `x32link` joined this list in ESP-035 — but adding it here was the SMALL half. That
+    /// unit had no mDNS whatsoever: it never advertised, so no matcher could have found it.
+    /// The user saw it exactly that way — "I see kstouch, not the headless" — while the box
+    /// sat there powered, on the network, and following the session.
+    private static let knownHostPrefixes = ["kitchensync", "kstouch", "x32link"]
 }

Tests/KitchenSyncAppTests/DeviceMatchTests.swift

@@ -47,4 +47,21 @@ final class DeviceMatchTests: XCTestCase {
                                                  txt: ["dev": "some-other-product"]),
                        "a TXT record that says it ISN'T ours must beat a hostname that says it is")
     }
+
+    /// ESP-035: the headless X32Link. It was the last unit in the fleet with NO mDNS at
+    /// all -- it never advertised, so it could not be found no matter what this matcher
+    /// did. Now it announces `x32link-<mac>`, and the prefix list has to know the name.
+    ///
+    /// The user hit this exactly: "I see kstouch. not the headless." The device was
+    /// powered, on the network, and following the Link session.
+    func test_the_headless_x32link_is_one_of_ours() {
+        XCTAssertTrue(DeviceMatch.isKitchenSync(serviceName: "x32link-7a1c", txt: nil))
+    }
+
+    /// The prefix is still a HEURISTIC, and it must not swallow the whole network. A
+    /// stranger's box at a venue is not ours.
+    func test_a_stranger_is_still_not_one_of_ours() {
+        XCTAssertFalse(DeviceMatch.isKitchenSync(serviceName: "brother-printer", txt: nil))
+        XCTAssertFalse(DeviceMatch.isKitchenSync(serviceName: "x32-mixer", txt: nil))
+    }
 }