G7 증명과 G8 clean-head 승격 준비

apps/api/app/config.py

@@ -153,7 +153,7 @@ class Settings(BaseSettings):
         validation_alias="VIGNETTE_LOCAL_WHISPER_STT_URL",
     )
     local_whisper_stt_model: str = Field(
-        default="large-v3",
+        default="small",
         validation_alias="VIGNETTE_LOCAL_WHISPER_STT_MODEL",
     )
     local_whisper_stt_language: str = Field(

apps/api/app/routes/voice.py

@@ -206,9 +206,13 @@ async def voice_health() -> JSONResponse:
         "stt_model": voice_service.stt_model(),
         "stt_batch_fallback_available": voice_service.batch_stt_available(),
         "tts_model": (
-            voice_svc.HIGGS_TTS_MODEL
-            if tts_provider == "higgs"
-            else voice_svc.TTS_MODEL
+            voice_svc.MELOTTS_TTS_MODEL
+            if tts_provider == "melotts"
+            else (
+                voice_svc.HIGGS_TTS_MODEL
+                if tts_provider == "higgs"
+                else voice_svc.TTS_MODEL
+            )
         ),
         "tts_provider": tts_provider,
         "limits": {

apps/api/app/services/session_metrics.py

@@ -3,7 +3,7 @@
 from __future__ import annotations
 
 from dataclasses import dataclass, field
-from datetime import datetime
+from datetime import datetime, timezone
 from typing import Any, Callable
 
 from ..store import InProcSession
@@ -44,7 +44,7 @@ class LearnerGrowthMetrics:
 def iso_datetime(ts: float | None) -> str | None:
     if ts is None:
         return None
-    return datetime.fromtimestamp(ts).isoformat(timespec="seconds")
+    return datetime.fromtimestamp(ts, tz=timezone.utc).isoformat(timespec="seconds")
 
 
 def session_activity_time(sess: InProcSession) -> float:

apps/api/app/services/voice.py

@@ -998,7 +998,7 @@ class VoiceService:
             local_whisper_stt_model
             if local_whisper_stt_model is not None
             else settings.local_whisper_stt_model
-        ).strip() or "large-v3"
+        ).strip() or "small"
         self._local_whisper_stt_language = (
             local_whisper_stt_language
             if local_whisper_stt_language is not None

apps/api/app/session_read_model.py

@@ -10,7 +10,7 @@ from __future__ import annotations
 import re
 from collections import Counter
 from dataclasses import dataclass
-from datetime import datetime
+from datetime import datetime, timedelta, timezone
 from typing import Any, Literal, Optional, cast
 
 from pydantic import BaseModel, Field
@@ -31,6 +31,7 @@ WorksheetItemSpec = tuple[str, str, list[str], WorksheetSpeaker | None]
 WorksheetSectionSpec = tuple[str, str, list[WorksheetItemSpec]]
 
 LEARNER_VISIBLE_AI_ROLE = "counselor"
+KOREA_STANDARD_TIME = timezone(timedelta(hours=9), name="KST")
 MISSING_SESSION_EVALUATION_GRACE_SECONDS = 30.0
 MISSING_SESSION_EVALUATION_ERROR = (
     "회기말 평가가 제한 시간 이후에도 저장되지 않았습니다. AI 평가 재시도가 필요합니다."
@@ -478,7 +479,11 @@ def stage_label(stage: object) -> StageLabel:
 def iso(ts: float | None) -> str | None:
     if ts is None:
         return None
-    return datetime.fromtimestamp(ts).isoformat(timespec="seconds")
+    return datetime.fromtimestamp(ts, tz=timezone.utc).isoformat(timespec="seconds")
+
+
+def session_calendar_date(ts: float) -> str:
+    return datetime.fromtimestamp(ts, tz=KOREA_STANDARD_TIME).strftime("%Y-%m-%d")
 
 
 def learner_visible_turns(sess: InProcSession) -> list[TurnRecord]:
@@ -1757,7 +1762,7 @@ def build_session_review(read_input: SessionReviewReadInput) -> SessionReviewRes
             initial=client_initial,
             persona=_persona_label(sess.persona_code, str(sess.persona.difficulty)),
         ),
-        date=datetime.fromtimestamp(sess.created_at).strftime("%Y-%m-%d"),
+        date=session_calendar_date(sess.created_at),
         durationLabel=_duration_label(duration_seconds),
         durationSeconds=duration_seconds,
         reachedPhase=reached_phase,

apps/api/app/test_session_read_model.py

@@ -0,0 +1,49 @@
+"""회기 읽기 모델의 시간 직렬화 계약 테스트."""
+
+from __future__ import annotations
+
+import unittest
+from datetime import datetime, timezone
+
+from .session_read_model import iso, session_calendar_date
+from .services.session_metrics import iso_datetime
+
+
+class SessionReadModelIsoTest(unittest.TestCase):
+    def test_none_remains_none(self) -> None:
+        self.assertIsNone(iso(None))
+
+    def test_epoch_is_serialized_as_utc_with_offset(self) -> None:
+        self.assertEqual(iso(0), "1970-01-01T00:00:00+00:00")
+
+    def test_timestamp_round_trips_without_local_timezone_drift(self) -> None:
+        timestamp = 1_800_000_120.0
+
+        rendered = iso(timestamp)
+
+        self.assertIsNotNone(rendered)
+        assert rendered is not None
+        parsed = datetime.fromisoformat(rendered)
+        self.assertEqual(parsed.tzinfo, timezone.utc)
+        self.assertEqual(parsed.timestamp(), timestamp)
+
+    def test_serialized_timestamp_has_explicit_utc_suffix(self) -> None:
+        rendered = iso(1_800_000_120.0)
+
+        self.assertIsNotNone(rendered)
+        assert rendered is not None
+        self.assertTrue(rendered.endswith("+00:00"))
+
+    def test_dashboard_metrics_use_the_same_utc_contract(self) -> None:
+        timestamp = 1_800_000_120.0
+
+        self.assertEqual(iso_datetime(timestamp), iso(timestamp))
+
+    def test_review_calendar_date_uses_korea_standard_time(self) -> None:
+        utc_late_afternoon = datetime(2026, 8, 8, 15, 30, tzinfo=timezone.utc)
+
+        self.assertEqual(session_calendar_date(utc_late_afternoon.timestamp()), "2026-08-09")
+
+
+if __name__ == "__main__":
+    unittest.main()

apps/api/app/test_voice_service.py

@@ -693,7 +693,7 @@ class LocalWhisperStreamingTest(unittest.IsolatedAsyncioTestCase):
         query = parse_qs(urlsplit(url).query)
         self.assertEqual(urlsplit(url).scheme, "ws")
         self.assertEqual(urlsplit(url).hostname, "127.0.0.1")
-        self.assertEqual(query["model"], ["large-v3"])
+        self.assertEqual(query["model"], ["small"])
         self.assertEqual(query["language"], ["ko"])
         self.assertEqual(query["sample_rate"], ["16000"])
         self.assertEqual(query["channels"], ["1"])
@@ -701,7 +701,7 @@ class LocalWhisperStreamingTest(unittest.IsolatedAsyncioTestCase):
         self.assertEqual(query["utterance_end_ms"], ["1200"])
 
         self.assertEqual(result.text, "안녕하세요")
-        self.assertEqual(result.model, "large-v3")
+        self.assertEqual(result.model, "small")
         self.assertEqual(result.language, "ko")
         self.assertEqual([word.word for word in result.words], ["안녕하세요"])
         self.assertAlmostEqual(result.words[0].start, 0.05, places=3)
@@ -927,7 +927,7 @@ class LocalWhisperProviderSelectionTest(unittest.TestCase):
         service = VoiceService(api_key="", stt_provider="local_whisper")
         self.assertTrue(service.streaming_stt_enabled())
         self.assertEqual(service.stt_provider(), "local_whisper")
-        self.assertEqual(service.stt_model(), "large-v3")
+        self.assertEqual(service.stt_model(), "small")
 
     def test_missing_sidecar_url_falls_back_to_batch(self) -> None:
         service = VoiceService(

apps/api/app/test_voice_ws.py

@@ -16,6 +16,7 @@ from .persona_repository import PersonaVoiceMap
 from .routes import voice as voice_routes
 from .services import multimodal_alliance_store
 from .services.voice import (
+    MELOTTS_TTS_MODEL,
     StreamingTranscriptEvent,
     TranscriptResult,
     TranscriptWord,
@@ -150,6 +151,27 @@ class _FakeRouteStreamingSession:
         self.aborted = True
 
 
+class VoiceHealthContractTest(unittest.IsolatedAsyncioTestCase):
+    async def test_melotts_health_reports_the_operated_model(self) -> None:
+        service = SimpleNamespace(
+            is_available=lambda: True,
+            stt_available=lambda: True,
+            tts_available=lambda: True,
+            tts_provider=lambda: "melotts",
+            stt_provider=lambda: "local_whisper",
+            stt_model=lambda: "small",
+            batch_stt_available=lambda: False,
+        )
+
+        with patch.object(voice_routes, "voice_service", service):
+            response = await voice_routes.voice_health()
+
+        body = json.loads(bytes(response.body))
+        self.assertEqual(body["status"], "ok")
+        self.assertEqual(body["tts_provider"], "melotts")
+        self.assertEqual(body["tts_model"], MELOTTS_TTS_MODEL)
+
+
 class VoiceWebSocketContractTest(unittest.IsolatedAsyncioTestCase):
     def _bind_result(self) -> tuple[str, VoicePreset, None, dict[str, object]]:
         return (