feat: improve voice studio alpha recovery flow

backend/app/api/voice_sessions.py

@@ -12,6 +12,7 @@ from fastapi import (
 )
 from sqlalchemy.ext.asyncio import AsyncSession
 
+from app.core.config import settings
 from app.core.deps import require_user
 from app.core.rate_limiter import check_rate_limit
 from app.db.database import get_db
@@ -34,11 +35,14 @@ from app.services.voice_session_service import (
     create_voice_turn_from_text_service,
     create_voice_turn_from_upload_service,
     finalize_voice_session_service,
+    get_latest_active_voice_session_service,
     get_voice_session_detail_service,
     get_voice_turn_audio_service,
     get_voice_turn_service,
     get_voice_turn_user_audio_service,
     list_voice_sessions_service,
+    retry_voice_turn_audio_service,
+    retry_voice_turn_service,
 )
 
 router = APIRouter()
@@ -68,8 +72,13 @@ async def create_voice_session(
 
 @router.get("/voice-sessions", response_model=list[VoiceSessionSummaryResponse])
 async def list_voice_sessions(
-    limit: int = Query(default=8, ge=1, le=20),
+    limit: int = Query(
+        default=settings.voice_session_default_list_limit,
+        ge=1,
+        le=settings.voice_session_max_list_limit,
+    ),
     active_only: bool = Query(default=False),
+    active_first: bool = Query(default=True),
     user: User = Depends(require_user),
     db: AsyncSession = Depends(get_db),
 ):
@@ -79,9 +88,19 @@ async def list_voice_sessions(
         db,
         limit=limit,
         active_only=active_only,
+        active_first=active_first,
     )
 
 
+@router.get("/voice-sessions/active", response_model=VoiceSessionSummaryResponse | None)
+async def get_latest_active_voice_session(
+    user: User = Depends(require_user),
+    db: AsyncSession = Depends(get_db),
+):
+    """Get the latest active voice session for quick resume behavior."""
+    return await get_latest_active_voice_session_service(user.id, db)
+
+
 @router.get("/voice-sessions/{session_id}", response_model=VoiceSessionDetailResponse)
 async def get_voice_session(
     session_id: str,
@@ -158,6 +177,21 @@ async def get_voice_turn(
     return await get_voice_turn_service(session_id, turn_id, user.id, db)
 
 
+@router.post(
+    "/voice-sessions/{session_id}/turns/{turn_id}/retry",
+    response_model=VoiceTurnAcceptedResponse,
+    status_code=status.HTTP_202_ACCEPTED,
+)
+async def retry_voice_turn(
+    session_id: str,
+    turn_id: str,
+    user: User = Depends(require_user),
+    db: AsyncSession = Depends(get_db),
+):
+    """Retry one failed voice turn using its saved transcript."""
+    return await retry_voice_turn_service(session_id, turn_id, user.id, db)
+
+
 @router.get("/voice-sessions/{session_id}/turns/{turn_id}/audio")
 async def get_voice_turn_audio(
     session_id: str,
@@ -170,6 +204,20 @@ async def get_voice_turn_audio(
     return Response(content=audio_bytes, media_type="audio/mpeg")
 
 
+@router.post(
+    "/voice-sessions/{session_id}/turns/{turn_id}/retry-audio",
+    response_model=VoiceTurnSummaryResponse,
+)
+async def retry_voice_turn_audio(
+    session_id: str,
+    turn_id: str,
+    user: User = Depends(require_user),
+    db: AsyncSession = Depends(get_db),
+):
+    """Retry assistant audio synthesis when one turn only has text output."""
+    return await retry_voice_turn_audio_service(session_id, turn_id, user.id, db)
+
+
 @router.get("/voice-sessions/{session_id}/turns/{turn_id}/user-audio")
 async def get_voice_turn_user_audio(
     session_id: str,