analyse: thread user.lang into the system prompt

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

app/routers/universe.py

@@ -36,7 +36,7 @@ from fastapi.responses import JSONResponse
 from sqlalchemy import and_, func, select
 from sqlalchemy.ext.asyncio import AsyncSession
 
-from app.auth import require_auth
+from app.auth import CurrentUser, require_auth
 from app.config import get_settings
 from app.db import get_session, utcnow
 from app.logging import get_logger
@@ -341,10 +341,11 @@ async def parse_portfolio(
 # ---------------------------------------------------------------------------
 
 
-@router.post("/analyze", dependencies=[Depends(require_paid)])
+@router.post("/analyze")
 async def analyze_portfolio(
     request: Request,
     session: AsyncSession = Depends(get_session),
+    principal: CurrentUser = Depends(require_paid),
 ) -> dict:
     """Generate AI commentary for the supplied pie. The pie is held in
     memory only for the duration of the LLM call; nothing about holdings
@@ -364,6 +365,11 @@ async def analyze_portfolio(
     except Exception:
         raise HTTPException(status_code=400, detail="malformed JSON body")
 
+    user_lang = (
+        principal.user.lang if (principal.user and principal.user.lang) else "en"
+    )
+    payload["lang"] = user_lang
+
     try:
         req = portfolio_analysis.parse_request(payload)
     except ValueError as e:

app/services/portfolio_analysis.py

@@ -31,6 +31,7 @@ from app.config import get_settings
 from app.db import utcnow
 from app.logging import get_logger
 from app.models import AICall
+from app.services.i18n import LANGUAGES, respond_in_clause
 from app.services.openrouter import (
     LogResult,
     active_model,
@@ -74,6 +75,7 @@ class AnalysisRequest:
     anchor: str | None = None
     tone: str = "INTERMEDIATE"     # NOVICE | INTERMEDIATE | PRO
     analysis: str = "SPECULATIVE"  # DRY | SPECULATIVE
+    lang: str = "en"
 
 
 @dataclass
@@ -163,10 +165,13 @@ def parse_request(payload: dict) -> AnalysisRequest:
     anchor = _sanitise_text(payload.get("anchor") or "", 32) or None
     tone = _sanitise_text(payload.get("tone", "INTERMEDIATE"), 16) or "INTERMEDIATE"
     analysis = _sanitise_text(payload.get("analysis", "SPECULATIVE"), 16) or "SPECULATIVE"
+    lang = (payload.get("lang") or "en").strip().lower()
+    if lang not in LANGUAGES:
+        lang = "en"
 
     return AnalysisRequest(
         positions=positions, prices=prices, base_currency=base_currency,
-        anchor=anchor, tone=tone, analysis=analysis,
+        anchor=anchor, tone=tone, analysis=analysis, lang=lang,
     )
 
 
@@ -276,7 +281,7 @@ def build_prompt(req: AnalysisRequest) -> tuple[str, str]:
     head = enriched[:MAX_POSITIONS_INLINED]
     tail_count = max(0, len(enriched) - MAX_POSITIONS_INLINED)
 
-    system = build_system_prompt(req.tone, req.analysis) + "\n\n" + _SYSTEM_OVERRIDES
+    system = build_system_prompt(req.tone, req.analysis) + "\n\n" + _SYSTEM_OVERRIDES + respond_in_clause(req.lang)
 
     user_parts = [
         f"# Portfolio commentary request — {utcnow().strftime('%Y-%m-%d')}",

tests/test_localization_integration.py

@@ -176,3 +176,77 @@ async def test_log_translation_fanout_per_language_failure_isolated(tmp_path, mo
     async with factory() as session:
         rows = (await session.execute(select(StrategicLogTranslation))).scalars().all()
     assert rows == []
+
+
+@pytest.mark.asyncio
+async def test_analyse_threads_lang_into_system_prompt(tmp_path, monkeypatch):
+    """When lang='it', the system prompt sent to call_llm contains
+    'Respond in Italian.' — the LLM does the rest."""
+    from app.services import portfolio_analysis as pa
+    from app.services.openrouter import LogResult
+
+    captured = {}
+
+    async def _fake_call_llm(client, messages, **kw):
+        captured["messages"] = messages
+        return LogResult(
+            content="Analisi del portafoglio in italiano.",
+            model="m", prompt_tokens=400, completion_tokens=100, cost_usd=0.0001,
+        )
+    monkeypatch.setattr(pa, "call_llm", _fake_call_llm)
+
+    _, factory, setup = _build_session_factory(tmp_path)
+    await setup()
+
+    payload = {
+        "positions": [{"yahoo_ticker": "AAPL", "qty": 10, "avg_cost": 150.0,
+                       "currency": "USD", "name": "Apple Inc"}],
+        "prices": {"AAPL": {"p": 172.4, "c": "USD"}},
+        "fx": {"USD": 1.0},
+        "base_currency": "USD",
+        "tone": "INTERMEDIATE",
+        "analysis": "NORMAL",
+        "lang": "it",
+    }
+    req = pa.parse_request(payload)
+    assert req.lang == "it"
+
+    async with factory() as session:
+        await pa.analyse(session, req)
+    system = next(m["content"] for m in captured["messages"] if m["role"] == "system")
+    assert "Respond in Italian" in system
+
+
+@pytest.mark.asyncio
+async def test_analyse_no_clause_when_lang_is_en(tmp_path, monkeypatch):
+    from app.services import portfolio_analysis as pa
+    from app.services.openrouter import LogResult
+
+    captured = {}
+
+    async def _fake_call_llm(client, messages, **kw):
+        captured["messages"] = messages
+        return LogResult(
+            content="Portfolio analysis in English.",
+            model="m", prompt_tokens=400, completion_tokens=100, cost_usd=0.0001,
+        )
+    monkeypatch.setattr(pa, "call_llm", _fake_call_llm)
+
+    _, factory, setup = _build_session_factory(tmp_path)
+    await setup()
+
+    payload = {
+        "positions": [{"yahoo_ticker": "AAPL", "qty": 10, "avg_cost": 150.0,
+                       "currency": "USD", "name": "Apple Inc"}],
+        "prices": {"AAPL": {"p": 172.4, "c": "USD"}},
+        "fx": {"USD": 1.0},
+        "base_currency": "USD",
+        "tone": "INTERMEDIATE",
+        "analysis": "NORMAL",
+        "lang": "en",
+    }
+    req = pa.parse_request(payload)
+    async with factory() as session:
+        await pa.analyse(session, req)
+    system = next(m["content"] for m in captured["messages"] if m["role"] == "system")
+    assert "Respond in" not in system