Add scoped NPC voice session lane

Unity/Assets/_SecondSpawn/Scripts/AI/AgentContextDto.cs

@@ -1404,5 +1404,45 @@ public sealed class VoiceSessionDto
         public string provider;
         public bool requires_ephemeral_token;
         public string reason;
+        public string actor_id;
+        public string body_id;
+        public string conversation_session_id;
+        public VoiceProfileDto voice_profile;
+        public VoiceSessionMaterialDto session;
+        public VoiceSessionDebugDto debug;
+    }
+
+    [Serializable]
+    public sealed class VoiceSessionRequestDto
+    {
+        public string actor_id;
+        public string conversation_session_id;
+        public string line_id;
+        public string playback_mode = "tts";
+        public int ttl_seconds = 90;
+        public string[] lip_sync_tiers;
+    }
+
+    [Serializable]
+    public sealed class VoiceSessionMaterialDto
+    {
+        public string session_id;
+        public long expires_at_ms;
+        public int ttl_seconds;
+        public string audience;
+        public string transport;
+        public string endpoint;
+        public string ephemeral_token;
+        public string[] lip_sync_tiers;
+        public bool presentation_only;
+        public string authority_note;
+    }
+
+    [Serializable]
+    public sealed class VoiceSessionDebugDto
+    {
+        public string source;
+        public string provider_status;
+        public string fallback_mode;
     }
 }

Unity/Assets/_SecondSpawn/Scripts/AI/PrototypeNPCChatClient.cs

@@ -10,7 +10,7 @@ namespace SecondSpawn.AI
     public sealed class PrototypeNPCChatClient : MonoBehaviour
     {
         [SerializeField] private bool _enablePrototypeHotkeys;
-        [SerializeField] private string _npcId = "prototype-guide";
+        [SerializeField] private string _npcId = "npc-synthetic-sentinel-0101";
         [SerializeField, TextArea] private string _prototypeMessage =
             "What should this body remember while I am offline?";
         [SerializeField] private Key _talkKey = Key.O;
@@ -63,7 +63,12 @@ private IEnumerator SendPrototypeChat()
 
         private IEnumerator CheckVoiceSession()
         {
-            yield return _gateway.GetVoiceSession(response =>
+            yield return _gateway.GetVoiceSession(new VoiceSessionRequestDto
+            {
+                actor_id = _npcId,
+                playback_mode = "voice_preview",
+                lip_sync_tiers = new[] { "text_timed", "audio_amplitude_hook" }
+            }, response =>
             {
                 Debug.Log($"[PrototypeNPCChatClient] Voice provider={response.provider}, available={response.voice_available}, reason={response.reason}");
             }, Debug.LogWarning);

Unity/Assets/_SecondSpawn/Scripts/AI/SecondSpawnGatewayClient.cs

@@ -430,14 +430,12 @@ public IEnumerator Chat(NpcChatRequestDto request, Action<NpcChatResponseDto> on
 
         public IEnumerator GetVoiceSession(Action<VoiceSessionDto> onSuccess, Action<string> onError = null)
         {
-            yield return null;
-            onSuccess?.Invoke(new VoiceSessionDto
-            {
-                voice_available = false,
-                provider = "not_configured",
-                requires_ephemeral_token = true,
-                reason = "Voice sessions require a future Nakama RPC that mints an api.dos.ai ephemeral token."
-            });
+            yield return GetVoiceSession(new VoiceSessionRequestDto(), onSuccess, onError);
+        }
+
+        public IEnumerator GetVoiceSession(VoiceSessionRequestDto request, Action<VoiceSessionDto> onSuccess, Action<string> onError = null)
+        {
+            yield return SendNakamaRpc("secondspawn_voice_session_request", request ?? new VoiceSessionRequestDto(), onSuccess, onError);
         }
 
         private IEnumerator SendNakamaRpc<TResponse>(

backend/nakama/README.md

@@ -133,6 +133,23 @@ circuit-open state and tries DOS.AI again. If the model still fails, the NPC
 does not invent a canned reply. It returns a degraded `stop` decision with the
 model failure reason so Unity can show `AI BACKOFF` or `AI FALLBACK` honestly.
 
+Optional scoped voice session env:
+
+```text
+DOS_AI_VOICE_SESSIONS_ENABLED=false
+DOS_AI_VOICE_SESSION_URL=https://api.dos.ai/v1/voice/sessions
+DOS_AI_VOICE_SESSION_TTL_SECONDS=90
+```
+
+`secondspawn_voice_session_request` is disabled by default. When enabled,
+Nakama uses `DOS_AI_API_KEY` server-side to ask `api.dos.ai` for short-lived
+voice playback material, then returns only a scoped session descriptor and an
+ephemeral token to Unity. The response is presentation-only and cannot mutate
+memory, relationships, quests, TIME, SECOND, inventory, combat, or body
+lifecycle state. When voice is disabled, unconfigured, timed out, or rejected,
+the RPC returns a structured text-only fallback so focused dialogue remains
+usable.
+
 ### Metrics and Structured Logs
 
 Nakama exposes its normal Prometheus-style server metrics through deployment
@@ -155,6 +172,9 @@ can filter prototype game events without parsing free-form text:
   duplicate claims.
 - `secondspawn.body_time_mutation` records accepted BodyTime changes and
   duplicate BodyTime events.
+- `secondspawn.voice_session` records voice session availability, provider,
+  fallback reason, target actor, and voice profile id without logging provider
+  keys or ephemeral tokens.
 
 Structured logs must stay public-safe: do not log provider API keys, RPC
 secrets, raw prompts, raw payloads, or private provider responses. Use