Merge remote-tracking branch 'origin/v3' into v3

# Conflicts:
#	tests/fixtures/architecture/dependency-baseline.json

app/application/messaging/chat.py

@@ -10,10 +10,12 @@ from weakref import WeakValueDictionary
 
 from app.application.database import (
     AsyncDatabaseExecutor,
+)
+from app.schemas.agent import AgentChatSessionDetail, AgentChatSessionSummary
+from app.schemas.exception import (
     DatabaseWorkerClosedError,
     DatabaseWorkerOverloadedError,
 )
-from app.schemas.agent import AgentChatSessionDetail, AgentChatSessionSummary
 from app.runtime.observability import record_metric