send path uses the device directory, not the prekey route — every send burned bundle quota and popped OPKs

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

client/src/main/kotlin/io/flamenet/client/Conversations.kt

@@ -378,7 +378,33 @@ class Conversations(
     }
 
     private fun sendPlaintext(toUserId: Long, text: String): Sent {
-        val bundles = relay.fetchKeys(toUserId)
+        // 🔴 **The DIRECTORY, not the key route.** `/e2e/keys` pops a one-time
+        // prekey per device and is metered per contact pair — calling it on
+        // EVERY send drained both, and an hour of ordinary chatting ended in
+        // "Too many attempts". The directory costs nothing; full bundles are
+        // fetched only when some device has no session yet, which is the one
+        // moment X3DH actually needs them.
+        val directory = relay.listDevices(toUserId)
+        val stubs = (0 until directory.length()).map { i ->
+            val o = directory.getJSONObject(i)
+            PeerBundle(
+                deviceId = o.optString("device_id"),
+                identityDH = runCatching { Wire.unb64(o.optString("ik_dh")) }
+                    .getOrDefault(ByteArray(0)),
+                identitySigning = runCatching { Wire.unb64(o.optString("ik_sig")) }
+                    .getOrDefault(ByteArray(0)),
+                signedPreKeyId = 0,
+                signedPreKey = ByteArray(0),
+                signedPreKeySignature = ByteArray(0),
+                oneTimePreKeyId = 0,
+                oneTimePreKey = null,
+                proto = o.optInt("proto", 1),
+            )
+        }
+        val needsEstablish = stubs.any {
+            it.deviceId != identity.deviceId && existingSession(it.deviceId) == null
+        }
+        val bundles = if (needsEstablish) relay.fetchKeys(toUserId) else stubs
         guardIdentity(toUserId, bundles)
         val delivered = mutableListOf<String>()
         val failed = LinkedHashMap<String, String>()