Sparse-day-proof briefs, feed health check, and 16 new sources

- Briefs now fill from a rolling window (prefer today, backfill up to
  window_days) and exclude anything featured in the last 7 days of briefs, so
  slow days still produce five items without stories lingering day to day.
- New 'check-feeds' command fetches and parses every feed to catch dead ones.
- Added 16 validated sources (science, environment, animals, culture),
  expanding coverage from 12 to 28 feeds to reduce staleness.

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

goodnews/briefs.py

@@ -9,6 +9,7 @@ def build_daily_brief(
     brief_date: str | None = None,
     limit: int = 5,
     replace: bool = False,
+    window_days: int = 3,
 ) -> int:
     target_date = brief_date or date.today().isoformat()
     existing = conn.execute("SELECT id FROM daily_briefs WHERE brief_date = ?", (target_date,)).fetchone()
@@ -22,7 +23,7 @@ def build_daily_brief(
         (target_date, f"Five Good Things Today - {target_date}"),
     ).lastrowid
 
-    rows = _candidate_articles(conn, target_date)
+    rows = _candidate_articles(conn, target_date, window_days)
     selected = _select_diverse(rows, limit)
     for index, row in enumerate(selected, start=1):
         conn.execute(
@@ -78,7 +79,17 @@ def show_brief(conn: sqlite3.Connection, brief_date: str | None = None, limit: i
     ).fetchall()
 
 
-def _candidate_articles(conn: sqlite3.Connection, target_date: str) -> list[sqlite3.Row]:
+def _candidate_articles(
+    conn: sqlite3.Connection, target_date: str, window_days: int = 3
+) -> list[sqlite3.Row]:
+    """Brief candidates, sparse-day-proof.
+
+    Prefers articles dated on target_date, but widens to the preceding
+    `window_days` so the brief still fills on slow news days. Anything already
+    featured in a brief within the last 7 days (other than this same date, which
+    is being rebuilt) is excluded so backfilled stories cannot linger across
+    consecutive days.
+    """
     return conn.execute(
         """
         SELECT
@@ -100,19 +111,31 @@ def _candidate_articles(conn: sqlite3.Connection, target_date: str) -> list[sqli
             s.pr_risk_score,
             s.reason_code,
             s.reason_text,
-            s.model_name
+            s.model_name,
+            CASE WHEN date(COALESCE(a.published_at, a.discovered_at)) = date(?)
+                 THEN 1 ELSE 0 END AS is_today
         FROM articles a
         JOIN sources src ON src.id = a.source_id
         JOIN article_scores s ON s.article_id = a.id
         WHERE s.accepted = 1
-          AND date(COALESCE(a.published_at, a.discovered_at)) = date(?)
+          AND date(COALESCE(a.published_at, a.discovered_at)) <= date(?)
+          AND date(COALESCE(a.published_at, a.discovered_at)) > date(?, '-' || ? || ' days')
+          AND a.id NOT IN (
+              SELECT bi.article_id
+              FROM daily_brief_items bi
+              JOIN daily_briefs b ON b.id = bi.brief_id
+              WHERE b.brief_date <> ?
+                AND b.brief_date <= date(?)
+                AND b.brief_date > date(?, '-7 days')
+          )
         ORDER BY
+            is_today DESC,
             (s.constructive_score + s.agency_score + s.human_benefit_score + src.trust_score
              - s.cortisol_score - s.ragebait_score - s.pr_risk_score) DESC,
             COALESCE(a.published_at, a.discovered_at) DESC
         LIMIT 50
         """,
-        (target_date,),
+        (target_date, target_date, target_date, window_days, target_date, target_date, target_date),
     ).fetchall()