refactor(okhttp): rename AmethystDns -> SurgeDns

"AmethystDns" identified the owner; "SurgeDns" identifies the
behavior. The class is built to absorb sudden bursts of concurrent
DNS work — 700 relays reconnecting, a feed scrolling through dozens
of media hosts, a profile screen requesting a NIP-05 — without
falling over: lock-free reads, single-flight coalescing, and
stale-while-revalidate so recurring hosts never block.

File renames:
- AmethystDns.kt        -> SurgeDns.kt
- AmethystDnsStore.kt   -> SurgeDnsStore.kt
- AmethystDnsTest.kt    -> SurgeDnsTest.kt

Symbol renames in every touchpoint (AppModules, factories,
managers, event listeners): AmethystDns -> SurgeDns,
amethystDns -> surgeDns.

amethyst/src/main/java/com/vitorpamplona/amethyst/AppModules.kt

@@ -53,12 +53,12 @@ import com.vitorpamplona.amethyst.service.location.LocationState
 import com.vitorpamplona.amethyst.service.notifications.AlwaysOnNotificationServiceManager
 import com.vitorpamplona.amethyst.service.notifications.NotificationDispatcher
 import com.vitorpamplona.amethyst.service.notifications.PokeyReceiver
-import com.vitorpamplona.amethyst.service.okhttp.AmethystDns
-import com.vitorpamplona.amethyst.service.okhttp.AmethystDnsStore
 import com.vitorpamplona.amethyst.service.okhttp.DualHttpClientManager
 import com.vitorpamplona.amethyst.service.okhttp.DualHttpClientManagerForRelays
 import com.vitorpamplona.amethyst.service.okhttp.EncryptionKeyCache
 import com.vitorpamplona.amethyst.service.okhttp.OkHttpWebSocket
+import com.vitorpamplona.amethyst.service.okhttp.SurgeDns
+import com.vitorpamplona.amethyst.service.okhttp.SurgeDnsStore
 import com.vitorpamplona.amethyst.service.playback.diskCache.VideoCache
 import com.vitorpamplona.amethyst.service.playback.diskCache.VideoCacheFactory
 import com.vitorpamplona.amethyst.service.playback.pip.BackgroundMedia
@@ -206,12 +206,12 @@ class AppModules(
     // Concurrent, caching DNS resolver shared by every OkHttp client built below — a host
     // resolved for an image fetch is reused when a relay handshake or NIP-05 lookup hits the
     // same host.
-    val amethystDns = AmethystDns()
+    val surgeDns = SurgeDns()
 
-    // Persists [amethystDns]'s positive cache across process restarts so cold starts don't pay
+    // Persists [surgeDns]'s positive cache across process restarts so cold starts don't pay
     // ~700 sync getaddrinfo calls. Restored entries fall through to the stale-while-revalidate
     // path on first lookup.
-    val dnsStore = AmethystDnsStore(appContext, amethystDns)
+    val dnsStore = SurgeDnsStore(appContext, surgeDns)
 
     // manages all the other connections separately from relays.
     val okHttpClients =
@@ -221,7 +221,7 @@ class AppModules(
             isMobileDataProvider = connManager.isMobileOrNull,
             keyCache = keyCache,
             scope = applicationIOScope,
-            dns = amethystDns,
+            dns = surgeDns,
         )
 
     // Offers easy methods to know when connections are happening through Tor or not
@@ -303,7 +303,7 @@ class AppModules(
             proxyPortProvider = torManager.activePortOrNull,
             isMobileDataProvider = connManager.isMobileOrNull,
             scope = applicationIOScope,
-            dns = amethystDns,
+            dns = surgeDns,
         )
 
     // Connects the INostrClient class with okHttp

amethyst/src/main/java/com/vitorpamplona/amethyst/service/okhttp/DnsInvalidatingEventListener.kt

@@ -25,7 +25,7 @@ import okhttp3.EventListener
 import java.io.IOException
 
 /**
- * Drops a host's [AmethystDns] entry whenever an OkHttp call to it fails outright. We hook
+ * Drops a host's [SurgeDns] entry whenever an OkHttp call to it fails outright. We hook
  * `callFailed` (final-stage signal after OkHttp has tried every address from the DNS lookup)
  * rather than per-attempt `connectFailed`: a multi-A-record host with one bad IP fires the
  * latter while OkHttp recovers via the next address, and we don't want to invalidate the cache
@@ -35,7 +35,7 @@ import java.io.IOException
  * invalidation into its `finish` method alongside its existing timing logging.
  */
 class DnsInvalidatingEventListener(
-    private val dns: AmethystDns,
+    private val dns: SurgeDns,
 ) : EventListener() {
     override fun callFailed(
         call: Call,
@@ -46,7 +46,7 @@ class DnsInvalidatingEventListener(
 
     /** Per-client factory. The listener is stateless, so the same instance serves every call. */
     class Factory(
-        dns: AmethystDns,
+        dns: SurgeDns,
     ) : EventListener.Factory {
         private val listener = DnsInvalidatingEventListener(dns)
 

amethyst/src/main/java/com/vitorpamplona/amethyst/service/okhttp/DualHttpClientManager.kt

@@ -38,7 +38,7 @@ class DualHttpClientManager(
     isMobileDataProvider: StateFlow<Boolean?>,
     keyCache: EncryptionKeyCache,
     scope: CoroutineScope,
-    dns: AmethystDns,
+    dns: SurgeDns,
 ) : IHttpClientManager {
     val factory = OkHttpClientFactory(keyCache, userAgent, dns)
 

amethyst/src/main/java/com/vitorpamplona/amethyst/service/okhttp/DualHttpClientManagerForRelays.kt

@@ -35,7 +35,7 @@ class DualHttpClientManagerForRelays(
     proxyPortProvider: StateFlow<Int?>,
     isMobileDataProvider: StateFlow<Boolean?>,
     scope: CoroutineScope,
-    dns: AmethystDns,
+    dns: SurgeDns,
 ) : IHttpClientManager {
     val factory = OkHttpClientFactoryForRelays(userAgent, dns)
 

amethyst/src/main/java/com/vitorpamplona/amethyst/service/okhttp/MediaCallEventListener.kt

@@ -44,7 +44,7 @@ import java.net.Proxy
 class MediaCallEventListener(
     private val dispatcher: Dispatcher,
     private val connectionPool: ConnectionPool,
-    private val dns: AmethystDns,
+    private val dns: SurgeDns,
 ) : EventListener() {
     private var callStartNanos = 0L
     private var dnsStartNanos = 0L
@@ -179,7 +179,7 @@ class MediaCallEventListener(
 class MediaCallEventListenerFactory(
     private val dispatcher: Dispatcher,
     private val connectionPool: ConnectionPool,
-    private val dns: AmethystDns,
+    private val dns: SurgeDns,
 ) : EventListener.Factory {
     override fun create(call: Call): EventListener = MediaCallEventListener(dispatcher, connectionPool, dns)
 }

amethyst/src/main/java/com/vitorpamplona/amethyst/service/okhttp/OkHttpClientFactory.kt

@@ -35,7 +35,7 @@ import java.util.concurrent.TimeUnit
 class OkHttpClientFactory(
     keyCache: EncryptionKeyCache,
     val userAgent: String,
-    private val dns: AmethystDns,
+    private val dns: SurgeDns,
 ) {
     // val logging = LoggingInterceptor()
     val keyDecryptor = EncryptedBlobInterceptor(keyCache)

amethyst/src/main/java/com/vitorpamplona/amethyst/service/okhttp/OkHttpClientFactoryForRelays.kt

@@ -29,7 +29,7 @@ import java.time.Duration
 
 class OkHttpClientFactoryForRelays(
     userAgent: String,
-    private val dns: AmethystDns,
+    private val dns: SurgeDns,
 ) {
     companion object {
         // by picking a random proxy port, the connection will fail as it should.

amethyst/src/main/java/com/vitorpamplona/amethyst/service/okhttp/SurgeDns.kt

@@ -69,7 +69,7 @@ import java.util.concurrent.atomic.AtomicBoolean
  * (unavoidable — there's nothing to serve stale yet), and followers waiting on that first
  * lookup block on `future.get()`. Background refreshes never block any caller.
  */
-class AmethystDns(
+class SurgeDns(
     private val delegate: Dns = Dns.SYSTEM,
     private val maxEntries: Int = 2000,
     private val positiveTtlMs: Long = TimeUnit.HOURS.toMillis(24),
@@ -286,7 +286,7 @@ class AmethystDns(
     }
 }
 
-/** Persistable record. Public so [AmethystDnsStore] can serialize it via Jackson. */
+/** Persistable record. Public so [SurgeDnsStore] can serialize it via Jackson. */
 data class DnsCacheRecord(
     val hostname: String,
     val addresses: List<String>,

amethyst/src/main/java/com/vitorpamplona/amethyst/service/okhttp/SurgeDnsStore.kt

@@ -26,7 +26,7 @@ import com.fasterxml.jackson.module.kotlin.readValue
 import com.vitorpamplona.quartz.utils.Log
 
 /**
- * Persists [AmethystDns]'s positive cache to a small `SharedPreferences` blob so the resolver
+ * Persists [SurgeDns]'s positive cache to a small `SharedPreferences` blob so the resolver
  * starts hot after a process restart.
  *
  * Cold starts are the resolver's worst case — every host is a sync `getaddrinfo`. With a
@@ -38,15 +38,15 @@ import com.vitorpamplona.quartz.utils.Log
  * list, Coil's image cache, and the system resolver's own state. ~700 entries × ~80 bytes ≈
  * ~55 KB of JSON.
  */
-class AmethystDnsStore(
+class SurgeDnsStore(
     private val context: Context,
-    private val dns: AmethystDns,
+    private val dns: SurgeDns,
 ) {
     private val prefs by lazy { context.getSharedPreferences(PREFS_NAME, Context.MODE_PRIVATE) }
 
     /**
      * Read the persisted snapshot and merge it into the resolver. Existing in-memory entries
-     * are preserved (see [AmethystDns.restore]). Safe to call once at app start. Blocking I/O —
+     * are preserved (see [SurgeDns.restore]). Safe to call once at app start. Blocking I/O —
      * call from a background thread.
      */
     fun load() {
@@ -93,7 +93,7 @@ class AmethystDnsStore(
     }
 
     companion object {
-        private const val TAG = "AmethystDnsStore"
+        private const val TAG = "SurgeDnsStore"
         private const val PREFS_NAME = "amethyst_dns_cache"
         private const val KEY_SNAPSHOT = "dns_cache_v1"
         private val MAPPER = jacksonObjectMapper()

amethyst/src/test/java/com/vitorpamplona/amethyst/service/okhttp/SurgeDnsTest.kt

@@ -37,7 +37,7 @@ import java.util.concurrent.TimeUnit
 import java.util.concurrent.atomic.AtomicInteger
 import java.util.concurrent.atomic.AtomicReference
 
-class AmethystDnsTest {
+class SurgeDnsTest {
     private fun ip(value: String) = InetAddress.getByName(value)
 
     private class CountingDns(
@@ -71,7 +71,7 @@ class AmethystDnsTest {
     @Test
     fun `cache hit avoids second upstream call`() {
         val upstream = CountingDns(mapOf("a.example" to listOf(ip("1.2.3.4"))))
-        val dns = AmethystDns(delegate = upstream)
+        val dns = SurgeDns(delegate = upstream)
 
         val first = dns.lookup("a.example")
         val second = dns.lookup("a.example")
@@ -84,7 +84,7 @@ class AmethystDnsTest {
     @Test
     fun `negative cache short-circuits subsequent lookups`() {
         val upstream = CountingDns(emptyMap())
-        val dns = AmethystDns(delegate = upstream)
+        val dns = SurgeDns(delegate = upstream)
 
         assertThrows(UnknownHostException::class.java) { dns.lookup("missing.example") }
         assertThrows(UnknownHostException::class.java) { dns.lookup("missing.example") }
@@ -97,7 +97,7 @@ class AmethystDnsTest {
         val upstream = CountingDns(mapOf("a.example" to listOf(ip("1.2.3.4"))))
         val syncRefresh = Executor { it.run() }
         val dns =
-            AmethystDns(
+            SurgeDns(
                 delegate = upstream,
                 positiveTtlMs = 1,
                 positiveTtlJitterMs = 0,
@@ -117,7 +117,7 @@ class AmethystDnsTest {
     fun `expired negative entry does not stale-while-revalidate`() {
         val upstream = CountingDns(emptyMap())
         val dns =
-            AmethystDns(
+            SurgeDns(
                 delegate = upstream,
                 positiveTtlJitterMs = 0,
                 negativeTtlMs = 1,
@@ -142,7 +142,7 @@ class AmethystDnsTest {
             }
         val syncRefresh = Executor { it.run() }
         val dns =
-            AmethystDns(
+            SurgeDns(
                 delegate = upstream,
                 positiveTtlMs = 1,
                 positiveTtlJitterMs = 0,
@@ -185,7 +185,7 @@ class AmethystDnsTest {
             }
         val pool = Executors.newFixedThreadPool(8)
         val dns =
-            AmethystDns(
+            SurgeDns(
                 delegate = dynamic,
                 positiveTtlMs = 1,
                 positiveTtlJitterMs = 0,
@@ -225,7 +225,7 @@ class AmethystDnsTest {
     @Test
     fun `concurrent lookups for the same host coalesce to one upstream call`() {
         val gated = GatedDns(mapOf("hot.example" to listOf(ip("9.9.9.9"))))
-        val dns = AmethystDns(delegate = gated)
+        val dns = SurgeDns(delegate = gated)
         val pool = Executors.newFixedThreadPool(8)
 
         try {
@@ -263,7 +263,7 @@ class AmethystDnsTest {
                     parallelism.decrementAndGet()
                 }
             }
-        val dns = AmethystDns(delegate = instrumented)
+        val dns = SurgeDns(delegate = instrumented)
         val pool = Executors.newFixedThreadPool(2)
 
         try {
@@ -289,7 +289,7 @@ class AmethystDnsTest {
     @Test
     fun `invalidate clears cache so next lookup hits upstream`() {
         val upstream = CountingDns(mapOf("a.example" to listOf(ip("1.2.3.4"))))
-        val dns = AmethystDns(delegate = upstream)
+        val dns = SurgeDns(delegate = upstream)
 
         dns.lookup("a.example")
         dns.invalidate()
@@ -307,7 +307,7 @@ class AmethystDnsTest {
                     "b.example" to listOf(ip("5.6.7.8")),
                 ),
             )
-        val dns = AmethystDns(delegate = upstream)
+        val dns = SurgeDns(delegate = upstream)
 
         dns.lookup("a.example")
         dns.lookup("b.example")
@@ -329,7 +329,7 @@ class AmethystDnsTest {
                 ),
             )
         val dns =
-            AmethystDns(
+            SurgeDns(
                 delegate = upstream,
                 positiveTtlMs = 60_000,
                 positiveTtlJitterMs = 0,
@@ -346,7 +346,7 @@ class AmethystDnsTest {
     @Test
     fun `restore replays cached entries without hitting upstream`() {
         val upstream = CountingDns(mapOf("relay.example" to listOf(ip("9.9.9.9"))))
-        val dns = AmethystDns(delegate = upstream)
+        val dns = SurgeDns(delegate = upstream)
 
         val expiresAt = System.currentTimeMillis() + 60_000
         dns.restore(listOf(DnsCacheRecord("relay.example", listOf("9.9.9.9"), expiresAt)))
@@ -358,7 +358,7 @@ class AmethystDnsTest {
     @Test
     fun `restore drops entries already expired on disk`() {
         val upstream = CountingDns(mapOf("relay.example" to listOf(ip("9.9.9.9"))))
-        val dns = AmethystDns(delegate = upstream)
+        val dns = SurgeDns(delegate = upstream)
 
         val expiredAt = System.currentTimeMillis() - 1_000
         dns.restore(listOf(DnsCacheRecord("relay.example", listOf("9.9.9.9"), expiredAt)))
@@ -371,7 +371,7 @@ class AmethystDnsTest {
     fun `restore does not overwrite a fresh in-memory entry`() {
         val upstream = CountingDns(mapOf("relay.example" to listOf(ip("1.1.1.1"))))
         val dns =
-            AmethystDns(
+            SurgeDns(
                 delegate = upstream,
                 positiveTtlMs = 60_000,
                 positiveTtlJitterMs = 0,
@@ -396,7 +396,7 @@ class AmethystDnsTest {
     @Test
     fun `lookup is case-insensitive`() {
         val upstream = CountingDns(mapOf("example.com" to listOf(ip("1.2.3.4"))))
-        val dns = AmethystDns(delegate = upstream)
+        val dns = SurgeDns(delegate = upstream)
 
         dns.lookup("Example.COM")
         dns.lookup("example.com")
@@ -408,7 +408,7 @@ class AmethystDnsTest {
     @Test
     fun `invalidate is case-insensitive`() {
         val upstream = CountingDns(mapOf("example.com" to listOf(ip("1.2.3.4"))))
-        val dns = AmethystDns(delegate = upstream)
+        val dns = SurgeDns(delegate = upstream)
 
         dns.lookup("example.com")
         dns.invalidate("EXAMPLE.com")
@@ -420,7 +420,7 @@ class AmethystDnsTest {
     @Test
     fun `restore lowercases hostnames so subsequent lookups hit`() {
         val upstream = CountingDns(mapOf("example.com" to listOf(ip("9.9.9.9"))))
-        val dns = AmethystDns(delegate = upstream)
+        val dns = SurgeDns(delegate = upstream)
 
         dns.restore(
             listOf(
@@ -436,7 +436,7 @@ class AmethystDnsTest {
     fun `dirty flag tracks positive writes`() {
         val upstream = CountingDns(mapOf("a.example" to listOf(ip("1.2.3.4"))))
         val dns =
-            AmethystDns(
+            SurgeDns(
                 delegate = upstream,
                 positiveTtlMs = 60_000,
                 positiveTtlJitterMs = 0,
@@ -455,7 +455,7 @@ class AmethystDnsTest {
     @Test
     fun `failed lookup does not mark cache dirty`() {
         val upstream = CountingDns(emptyMap())
-        val dns = AmethystDns(delegate = upstream)
+        val dns = SurgeDns(delegate = upstream)
 
         assertFalse(dns.isDirty())
         runCatching { dns.lookup("missing.example") }
@@ -471,7 +471,7 @@ class AmethystDnsTest {
             }
         val syncRefresh = Executor { it.run() }
         val dns =
-            AmethystDns(
+            SurgeDns(
                 delegate = upstream,
                 positiveTtlMs = 1,
                 positiveTtlJitterMs = 0,
@@ -499,7 +499,7 @@ class AmethystDnsTest {
         val upstream = CountingDns(mapOf("a.example" to listOf(ip("1.2.3.4"))))
         val rejecting = Executor { throw RejectedExecutionException("test") }
         val dns =
-            AmethystDns(
+            SurgeDns(
                 delegate = upstream,
                 positiveTtlMs = 1,
                 positiveTtlJitterMs = 0,