log: serve localized content from the HTMX endpoints

The /log page renders its content asynchronously by hitting
/api/log/latest?as=html and /api/log/by-date/{day}?as=html via HTMX.
Both endpoints returned StrategicLog.content (English) verbatim,
ignoring the new StrategicLogTranslation table entirely. The
_resolve_log_content helper I added to pages.py earlier was wired
into the page handlers themselves but never reached for HTMX swaps,
so Italian users only ever saw English content despite their
lang='it' preference being persisted and translations being
generated correctly.

Fix: add a _localized_content helper in api.py that looks up the
matching translation row for the requesting principal's lang.
_log_partial_payload gains a content_override arg; both HTMX
endpoints (log_latest, log_by_date) compute the override and pass
it through. JSON paths (?as= other than html) remain English to
avoid changing the public API contract.

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

app/routers/api.py

@@ -39,6 +39,7 @@ from app.models import (
     JobRun,
     Quote,
     StrategicLog,
+    StrategicLogTranslation,
     User,
 )
 from app.schemas import (
@@ -297,11 +298,15 @@ async def news_list(
 # --- Strategic log -----------------------------------------------------------
 
 
-def _log_partial_payload(row: StrategicLog | None) -> dict | None:
+def _log_partial_payload(
+    row: StrategicLog | None,
+    content_override: str | None = None,
+) -> dict | None:
     if row is None:
         return None
+    content = content_override if content_override is not None else row.content
     return {
-        "content_html": _md_to_html(row.content),
+        "content_html": _md_to_html(content),
         "generated_at": row.generated_at,
         "model": row.model,
         "tone": row.tone,
@@ -313,6 +318,28 @@ def _log_partial_payload(row: StrategicLog | None) -> dict | None:
     }
 
 
+async def _localized_content(
+    session: AsyncSession,
+    row: StrategicLog | None,
+    principal: CurrentUser | None,
+) -> str | None:
+    """Return the translated content_md for ``row`` when the principal has
+    a non-English lang preference and a matching translation row exists.
+    Returns None to signal 'use row.content as-is' (the default English
+    path)."""
+    if row is None or principal is None or principal.user is None:
+        return None
+    lang = (principal.user.lang or "en")
+    if lang == "en":
+        return None
+    t = (await session.execute(
+        select(StrategicLogTranslation)
+        .where(StrategicLogTranslation.log_id == row.id)
+        .where(StrategicLogTranslation.lang == lang)
+    )).scalar_one_or_none()
+    return t.content_md if t is not None else None
+
+
 def _resolve_tone_param(tone: str | None) -> str:
     """Normalise a query-param tone to one of the two valid values.
     PRO is silently mapped to INTERMEDIATE (see openrouter.PROMPT_VERSION 6)."""
@@ -368,10 +395,11 @@ async def log_latest(
         row = (await session.execute(fallback)).scalar_one_or_none()
 
     if as_ == "html":
+        content_override = await _localized_content(session, row, principal)
         return templates.TemplateResponse(
             request, "partials/log.html",
-            {"log": _log_partial_payload(row), "tone": wanted_tone,
+            {"log": _log_partial_payload(row, content_override=content_override),
-             "paid": not free_only},
+             "tone": wanted_tone, "paid": not free_only},
         )
 
     if row is None:
@@ -422,10 +450,11 @@ async def log_by_date(
         row = (await session.execute(fallback)).scalar_one_or_none()
 
     if as_ == "html":
+        content_override = await _localized_content(session, row, principal)
         return templates.TemplateResponse(
             request, "partials/log.html",
-            {"log": _log_partial_payload(row), "tone": wanted_tone,
+            {"log": _log_partial_payload(row, content_override=content_override),
-             "paid": not free_only},
+             "tone": wanted_tone, "paid": not free_only},
         )
     if row is None:
         raise HTTPException(status_code=404, detail="No log on this date")