log: serve translated content when available; English fallback

Adds module-level _resolve_log_content(session, log_id, lang) helper
to app/routers/pages.py: looks up StrategicLogTranslation by (log_id,
lang) when lang != 'en'; falls back silently to the English original
when no translation row exists yet (the expected case for the first
hour after a new language activates, or when translation fails for a
specific log).

log_page / log_page_day pull cu.user.lang and thread it through
_log_page_context so the template renders the right variant.

Two tests cover both branches.

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

tests/test_localization_integration.py

@@ -332,3 +332,66 @@ def test_digest_pick_variant_uses_user_lang():
     assert ed._pick_variant(table, tone="NOVICE", lang="de") == "novice en"
     # Missing tone → fallback to INTERMEDIATE/en (the safe default).
     assert ed._pick_variant(table, tone="UNKNOWN", lang="en") == "intermediate en"
+
+
+@pytest.mark.asyncio
+async def test_log_endpoint_serves_italian_when_user_is_italian(tmp_path):
+    """When a user with lang='it' opens /log, the served content is the
+    Italian translation, not the English original."""
+    from app.db import utcnow
+    from app.models import StrategicLog, StrategicLogTranslation, User
+
+    _, factory, setup = _build_session_factory(tmp_path)
+    await setup()
+
+    async with factory() as session:
+        session.add(User(id=10, email="it@x", tier="paid", lang="it"))
+        slog = StrategicLog(
+            generated_at=utcnow(), content="# Open\n\nDown 0.4%.",
+            model="test-model",
+            tone="INTERMEDIATE", analysis="NORMAL",
+        )
+        session.add(slog)
+        await session.commit()
+        session.add(StrategicLogTranslation(
+            log_id=slog.id, lang="it",
+            content_md="# Apertura\n\nIn calo 0,4%.",
+            generated_at=utcnow(), llm_model="m", llm_cost_usd=0.0,
+        ))
+        await session.commit()
+        log_id = slog.id
+
+    # Test the resolver directly.
+    from app.routers.pages import _resolve_log_content
+    async with factory() as session:
+        user = await session.get(User, 10)
+        content = await _resolve_log_content(session, log_id, user.lang)
+    assert "Apertura" in content
+    assert "Open" not in content
+
+
+@pytest.mark.asyncio
+async def test_log_endpoint_falls_back_to_english_when_no_translation(tmp_path):
+    """User lang='it' but no IT translation exists → English fallback."""
+    from app.db import utcnow
+    from app.models import StrategicLog, User
+
+    _, factory, setup = _build_session_factory(tmp_path)
+    await setup()
+
+    async with factory() as session:
+        session.add(User(id=11, email="it2@x", tier="paid", lang="it"))
+        slog = StrategicLog(
+            generated_at=utcnow(), content="# Open\n\nDown 0.4%.",
+            model="test-model",
+            tone="INTERMEDIATE", analysis="NORMAL",
+        )
+        session.add(slog)
+        await session.commit()
+        log_id = slog.id
+
+    from app.routers.pages import _resolve_log_content
+    async with factory() as session:
+        user = await session.get(User, 11)
+        content = await _resolve_log_content(session, log_id, user.lang)
+    assert "Open" in content