diff --git a/README.md b/README.md
index b1385d6..8023c33 100644
--- a/README.md
+++ b/README.md
@@ -142,7 +142,7 @@ The primary configuration components are:
 | Typed configuration | `config/models.py` |
 | Provider catalog | `config/providers.yaml` |
 | Dynamic provider loading | `providers.py` |
-| Session lifecycle | `audio_gateway/app/session.py` |
+| Session lifecycle | `domain/session.py` |
 | Semantic turn lifecycle | `turn_manager.py` |
 | Execution orchestration | `voice_pipeline.py` |
 
@@ -380,7 +380,8 @@ The script reads `audios/chafik_normalize.wav` (16 kHz, mono, 16-bit PCM), sends
 ```text
 config/                         Environment YAML and provider catalog
 src/voice_assistant/
-  audio_gateway/app/            WebSocket endpoint, protocol, session state
+  audio_gateway/app/            WebSocket endpoint and protocol
+  domain/                       Session state and domain rules
   audio/                        Canonical audio models
   stt/                          STT contract, mock and NVIDIA adapter
   agent/                        Agent contract and mock adapter
diff --git a/src/voice_assistant/audio_gateway/app/main.py b/src/voice_assistant/audio_gateway/app/main.py
index 2bc9c6c..bcf0f35 100644
--- a/src/voice_assistant/audio_gateway/app/main.py
+++ b/src/voice_assistant/audio_gateway/app/main.py
@@ -99,7 +99,7 @@ from voice_assistant.voice_pipeline import (
 )
 
 
-from voice_assistant.audio_gateway.app.session import SessionState
+from voice_assistant.domain.session import SessionState
 
 # logger configuration
 logger = logging.getLogger(__name__)
diff --git a/src/voice_assistant/domain/__init__.py b/src/voice_assistant/domain/__init__.py
new file mode 100644
index 0000000..4ddcb32
--- /dev/null
+++ b/src/voice_assistant/domain/__init__.py
@@ -0,0 +1 @@
+"""Domain models and rules independent of transport and providers."""
diff --git a/src/voice_assistant/audio_gateway/app/session.py b/src/voice_assistant/domain/session.py
similarity index 100%
rename from src/voice_assistant/audio_gateway/app/session.py
rename to src/voice_assistant/domain/session.py
diff --git a/src/voice_assistant/voice_pipeline.py b/src/voice_assistant/voice_pipeline.py
index 54d69ae..8a4114b 100644
--- a/src/voice_assistant/voice_pipeline.py
+++ b/src/voice_assistant/voice_pipeline.py
@@ -46,7 +46,7 @@ from contextlib import aclosing
 from voice_assistant.agent.text_chunker import TextChunker
 from voice_assistant.turn_manager import TurnState
 from voice_assistant.agent.adapter import AgentAdapter
-from voice_assistant.audio_gateway.app.session import SessionState
+from voice_assistant.domain.session import SessionState
 from voice_assistant.turn_manager import Turn, TurnManager
 from voice_assistant.tts.adapter import TTSAdapter
 
diff --git a/tests/test_session_turn_lifecycle.py b/tests/test_session_turn_lifecycle.py
index 9e8a912..88309ce 100644
--- a/tests/test_session_turn_lifecycle.py
+++ b/tests/test_session_turn_lifecycle.py
@@ -19,7 +19,7 @@ Non-responsibilities:
 
 import pytest
 
-from voice_assistant.audio_gateway.app.session import SessionState
+from voice_assistant.domain.session import SessionState
 from voice_assistant.turn_manager import TurnManager, TurnState
 
 
diff --git a/tests/test_voice_pipeline.py b/tests/test_voice_pipeline.py
index 37f8ae3..8577b28 100644
--- a/tests/test_voice_pipeline.py
+++ b/tests/test_voice_pipeline.py
@@ -27,7 +27,7 @@ from voice_assistant.voice_pipeline import (
     VoicePipeline,
 )
 
-from voice_assistant.audio_gateway.app.session import SessionState
+from voice_assistant.domain.session import SessionState
 from voice_assistant.turn_manager import TurnManager, TurnState
 from voice_assistant.agent.mock import MockAgentAdapter
 from voice_assistant.tts.mock import MockTTSAdapter