Images phase 1: attention-triggered og:image coverage

Tie image enrichment to attention (per review): when an article earns a summary
(i.e. a reader reached it), best-effort fetch a real og:image if it lacks one —
never blanket-fetch every ingested article. Adds:

* enrich_article_image() — single-article fetch, leaves existing images alone,
  retries an imageless article only after 7 days, stamps image_checked_at.
* generate_summary() calls it after caching (wrapped; never breaks summaries).
* enrich_summarized_images() + `goodnews enrich-images` CLI — slow background
  backfill of already-summarized, accepted, imageless articles.
* Quality gate: extend the generic-image skip list with data:/tracking-pixel/
  spacer markers (on top of the existing logo/placeholder + unbranded-BBC logic).

This is coverage only; display (editorial rhythm, tile treatment) comes next.

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

goodnews/enrich.py

@@ -50,6 +50,13 @@ _GENERIC_IMAGE_MARKERS = (
     "/placeholder",
     "share-default",
     "social-default",
+    # tracking pixels / spacers / data-URIs — never a real share image
+    "data:image",
+    "/pixel",
+    "1x1",
+    "spacer",
+    "/blank.",
+    "transparent.",
 )
 
 
@@ -207,3 +214,64 @@ def enrich_brief_images(
             found += 1
     conn.commit()
     return found
+
+
+def enrich_article_image(
+    conn: sqlite3.Connection, article_id: int, fetch=fetch_og_image, retry_days: int = 7
+) -> bool:
+    """Attention-triggered: fetch an og:image for ONE article that lacks one.
+
+    Called when an article earns a summary (i.e. it's actually being read), so we
+    only spend a fetch on articles a reader has reached. Leaves an existing image
+    alone; retries a still-imageless article only after `retry_days`. Returns True
+    if a new image was stored. Best-effort — never raises.
+    """
+    row = conn.execute(
+        """
+        SELECT id, canonical_url FROM articles
+        WHERE id = ?
+          AND (image_url IS NULL OR image_url = '')
+          AND (image_checked_at IS NULL OR image_checked_at < datetime('now', ?))
+        """,
+        (article_id, f"-{retry_days} days"),
+    ).fetchone()
+    if not row:
+        return False  # has an image already, or checked too recently
+    try:
+        image = fetch(row["canonical_url"])
+    except Exception:
+        image = None
+    conn.execute(
+        "UPDATE articles SET image_url = COALESCE(?, image_url), image_checked_at = CURRENT_TIMESTAMP "
+        "WHERE id = ?",
+        (image, article_id),
+    )
+    conn.commit()
+    return bool(image)
+
+
+def enrich_summarized_images(
+    conn: sqlite3.Connection, fetch=fetch_og_image, limit: int = 50, retry_days: int = 7
+) -> int:
+    """Slow backfill: give already-summarized, accepted articles an image if they
+    lack one. Run in modest batches so we never blast publishers. Returns count
+    of newly-found images.
+    """
+    rows = conn.execute(
+        """
+        SELECT a.id FROM articles a
+        JOIN article_summaries m ON m.article_id = a.id
+        JOIN article_scores s ON s.article_id = a.id
+        WHERE s.accepted = 1 AND a.duplicate_of IS NULL
+          AND (a.image_url IS NULL OR a.image_url = '')
+          AND (a.image_checked_at IS NULL OR a.image_checked_at < datetime('now', ?))
+        ORDER BY a.id DESC
+        LIMIT ?
+        """,
+        (f"-{retry_days} days", limit),
+    ).fetchall()
+    found = 0
+    for row in rows:
+        if enrich_article_image(conn, row["id"], fetch=fetch, retry_days=retry_days):
+            found += 1
+    return found