fix(region): compare /region codes with CONTINENT, not REGION

velocity/src/main/kotlin/gg/grounds/proxy/velocity/GroundsProxyPlugin.kt

@@ -170,7 +170,7 @@ constructor(private val proxy: ProxyServer, private val logger: Logger) {
         // Looked up per invocation rather than captured: the registry is written during startup and
         // a reference taken now could be the one from before another plugin registered.
         val service = { ProxyServiceRegistry.get(ProxyService::class.java) }
-        val region = { System.getenv("REGION")?.trim()?.takeIf(String::isNotEmpty) }
+        val region = { RegionCatalog.currentCode() }
         proxy.commandManager.register("online", OnlineCommand(service))
         proxy.commandManager.register("region", RegionCommand(catalog, region, service))
 

velocity/src/main/kotlin/gg/grounds/proxy/velocity/RegionCatalog.kt

@@ -29,6 +29,18 @@ class RegionCatalog(val regions: List<Region>, val problems: List<String>) {
         get() = regions.map { it.code }
 
     companion object {
+        /**
+         * Which catalogue code this proxy answers for. The catalogue is keyed by continent (`eu`),
+         * not by datacentre (`de-nbg1`), so `CONTINENT` is what a code compares against. `REGION`
+         * is the fallback for a catalogue still keyed by datacentre, where the two are the same.
+         */
+        fun currentCode(
+            continent: String? = System.getenv("CONTINENT"),
+            region: String? = System.getenv("REGION"),
+        ): String? =
+            continent?.trim()?.takeIf(String::isNotEmpty)
+                ?: region?.trim()?.takeIf(String::isNotEmpty)
+
         fun fromEnvironment(
             raw: String? = System.getenv("REGIONS"),
             defaultPort: Int = ProxyService.DEFAULT_MINECRAFT_PORT,

velocity/src/test/kotlin/gg/grounds/proxy/velocity/RegionCatalogTest.kt

@@ -47,4 +47,16 @@ class RegionCatalogTest {
         assertTrue(catalog.problems.isEmpty())
         assertNull(catalog["nl-ams1"])
     }
+
+    /** The catalogue is keyed by continent; comparing with the datacentre never matches. */
+    @Test
+    fun `current code is the continent, not the datacentre`() {
+        assertEquals("eu", RegionCatalog.currentCode(continent = "eu", region = "de-nbg1"))
+    }
+
+    @Test
+    fun `current code falls back to the region when no continent is set`() {
+        assertEquals("nl-ams1", RegionCatalog.currentCode(continent = " ", region = "nl-ams1"))
+        assertNull(RegionCatalog.currentCode(continent = null, region = null))
+    }
 }