Personalized brief: refill to full count when a boundary hides a highlight

When a reader's boundary (avoid-term, muted topic/flavor, pause) removes a brief
item, top the highlights back up with other readable, boundary-respecting good
news instead of showing fewer cards — so 'Highlights from Today' stays full and
still honors what they don't want to see. (Reverses the earlier filter-down-only
MVP, now that the count is fixed at seven.)

- /api/brief: after filtering by prefs, refill from the accepted pool (same
  categorical SQL filters + avoid-terms) excluding already-shown items.
- Shared _prefs_sql_kw helper for feed/replacement/brief filters.
- Tests: refill stays full and respects mute + avoid-terms (89 total).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

goodnews/api.py

@@ -57,6 +57,18 @@ def get_conn():
         conn.close()
 
 
+def _prefs_sql_kw(fp, now) -> dict:
+    """Categorical prefs → queries.feed keyword filters (avoid-terms stay Python)."""
+    return dict(
+        include_topics=fp.include_topics or None,
+        include_flavors=fp.include_flavors or None,
+        mute_topics=list(fp.muted_topics(now)) or None,
+        mute_flavors=list(fp.muted_flavors(now)) or None,
+        max_cortisol=fp.max_cortisol,
+        max_ragebait=fp.max_ragebait,
+    )
+
+
 def _pick_lead(items: list[dict]) -> list[dict]:
     """Lead with a gentle, readable, ideally illustrated story.
 
@@ -303,15 +315,28 @@ def create_app() -> FastAPI:
         prefs: str | None = Query(None),
     ) -> BriefResponse:
         fp = prefs_from_json(prefs)
+        now = datetime.now(timezone.utc)
         with get_conn() as conn:
             data = queries.brief(conn, brief_date=date, limit=limit)
-        items = data["items"]
-        if not fp.is_empty():
-            # MVP: filter the stored brief DOWN; no refill from outside the brief.
-            # Runs before hero selection, so personal avoid-terms take precedence.
-            items = filter_articles(items, fp, datetime.now(timezone.utc))
+            items = data["items"]
+            if not fp.is_empty():
+                # Apply personal boundaries (avoid-terms take precedence over curation).
+                items = filter_articles(items, fp, now)
+                # Keep the highlights full: if a boundary hid a story, top up with
+                # other readable, boundary-respecting good news rather than show fewer.
+                if len(items) < limit:
+                    have = {a["id"] for a in items}
+                    pool = queries.feed(
+                        conn, accepted_only=True, limit=limit * 5 + 20, offset=0, **_prefs_sql_kw(fp, now)
+                    )
+                    for a in filter_articles(pool, fp, now):
+                        if len(items) >= limit:
+                            break
+                        if a["id"] not in have:
+                            items.append(a)
+                            have.add(a["id"])
         # Lead with a gentle, readable story (charged or paywalled stories stay
-        # in the five, just not as the first thing seen).
+        # in the set, just not as the first thing seen).
         items = _pick_lead(items)
         return BriefResponse(
             brief_date=data["brief_date"],