Add topic/flavor categorization and category browsing

- New taxonomy module: single source of truth for 6 topics x 5 flavors,
  shared by the LLM response schema (enum-constrained) and validation.
- Classifier now assigns one topic + one flavor per article; json_schema
  enums force valid values, with coercion as a safety net.
- article_scores gains topic/flavor columns via an idempotent migration.
- New 'list-category' command to browse by topic and/or flavor, ranked by
  composite score.

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

goodnews/cli.py

@@ -38,6 +38,12 @@ def main() -> None:
     source_parser = subparsers.add_parser("list-sources", help="Show configured sources")
     source_parser.add_argument("--active-only", action="store_true")
 
+    cat_parser = subparsers.add_parser("list-category", help="Browse articles by topic and/or flavor")
+    cat_parser.add_argument("--topic", help="Filter by topic, e.g. science, environment, animals")
+    cat_parser.add_argument("--flavor", help="Filter by flavor, e.g. breakthrough, discovery, feelgood")
+    cat_parser.add_argument("--limit", type=int, default=20)
+    cat_parser.add_argument("--all", action="store_true", help="Include not-accepted articles")
+
     subparsers.add_parser("source-report", help="Show source-level ingestion and scoring stats")
 
     runs_parser = subparsers.add_parser("list-runs", help="Show recent ingest runs")
@@ -90,6 +96,8 @@ def main() -> None:
         list_recent(conn, limit=args.limit, accepted_only=args.accepted_only)
     elif args.command == "list-sources":
         list_sources(conn, active_only=args.active_only)
+    elif args.command == "list-category":
+        list_category(conn, topic=args.topic, flavor=args.flavor, limit=args.limit, accepted_only=not args.all)
     elif args.command == "source-report":
         source_report(conn)
     elif args.command == "list-runs":
@@ -109,7 +117,10 @@ def main() -> None:
         )
         for article_id, scores in results:
             accepted = "yes" if scores["accepted"] else "no"
-            print(f"[{article_id}] accepted={accepted} reason={scores['reason_code']}")
+            print(
+                f"[{article_id}] accepted={accepted} {scores['topic']}/{scores['flavor']} "
+                f"reason={scores['reason_code']}"
+            )
             print(f"  {scores['reason_text']}")
         if args.dry_run:
             print("Dry run only; database was not updated.")
@@ -179,6 +190,55 @@ def list_recent(conn: sqlite3.Connection, limit: int, accepted_only: bool) -> No
         print(f"  {row['canonical_url']}")
 
 
+def list_category(
+    conn: sqlite3.Connection,
+    topic: str | None,
+    flavor: str | None,
+    limit: int,
+    accepted_only: bool,
+) -> None:
+    clauses = []
+    params: list = []
+    if accepted_only:
+        clauses.append("s.accepted = 1")
+    if topic:
+        clauses.append("s.topic = ?")
+        params.append(topic.lower())
+    if flavor:
+        clauses.append("s.flavor = ?")
+        params.append(flavor.lower())
+    where = ("WHERE " + " AND ".join(clauses)) if clauses else ""
+    params.append(limit)
+
+    rows = conn.execute(
+        f"""
+        SELECT
+            a.id, a.title, a.canonical_url, a.published_at,
+            src.name AS source_name,
+            s.topic, s.flavor, s.accepted,
+            s.constructive_score, s.cortisol_score, s.reason_code,
+            (s.constructive_score + s.agency_score + s.human_benefit_score + src.trust_score
+             - s.cortisol_score - s.ragebait_score - s.pr_risk_score) AS rank_score
+        FROM articles a
+        JOIN sources src ON src.id = a.source_id
+        JOIN article_scores s ON s.article_id = a.id
+        {where}
+        ORDER BY rank_score DESC, COALESCE(a.published_at, a.discovered_at) DESC
+        LIMIT ?
+        """,
+        params,
+    ).fetchall()
+
+    label = " / ".join(filter(None, [topic, flavor])) or "all categories"
+    print(f"{label} ({len(rows)} shown)")
+    for row in rows:
+        accepted = "" if row["accepted"] else " [not accepted]"
+        print(f"[{row['id']}] {row['topic']}/{row['flavor']} | {row['source_name']}{accepted}")
+        print(f"  {row['title']}")
+        print(f"  score={row['rank_score']} reason={row['reason_code']}")
+        print(f"  {row['canonical_url']}")
+
+
 def llm_client_from_args(args: argparse.Namespace) -> LocalModelClient:
     client = LocalModelClient.from_env()
     if getattr(args, "base_url", None):