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>

tests/test_enrich_images.py

@@ -0,0 +1,58 @@
+from goodnews.db import connect, init_db
+from goodnews import enrich
+
+
+def _setup(tmp_path):
+    c = connect(str(tmp_path / "t.db")); init_db(c)
+    c.execute("INSERT INTO sources (id,name,feed_url) VALUES (1,'S','http://s/f')")
+    return c
+
+
+def _add(c, aid, *, image=None, accepted=1, dup=None, summarized=True):
+    c.execute(
+        "INSERT INTO articles (id,source_id,canonical_url,title,url_hash,image_url,duplicate_of,published_at) "
+        "VALUES (?,1,?,?,?,?,?,datetime('now'))",
+        (aid, f"http://s/{aid}", f"T{aid}", f"h{aid}", image, dup),
+    )
+    c.execute("INSERT INTO article_scores (article_id,accepted) VALUES (?,?)", (aid, accepted))
+    if summarized:
+        c.execute("INSERT INTO article_summaries (article_id,summary) VALUES (?, 's')", (aid,))
+    c.commit()
+
+
+def test_enrich_article_image_fills_missing(tmp_path):
+    c = _setup(tmp_path); _add(c, 1, image=None)
+    got = enrich.enrich_article_image(c, 1, fetch=lambda url: "http://img/og.jpg")
+    assert got is True
+    assert c.execute("SELECT image_url FROM articles WHERE id=1").fetchone()[0] == "http://img/og.jpg"
+    # image_checked_at is stamped so we don't re-fetch endlessly
+    assert c.execute("SELECT image_checked_at FROM articles WHERE id=1").fetchone()[0] is not None
+
+
+def test_enrich_skips_when_image_present(tmp_path):
+    c = _setup(tmp_path); _add(c, 1, image="http://existing/img.jpg")
+    calls = []
+    got = enrich.enrich_article_image(c, 1, fetch=lambda url: calls.append(url) or "http://new.jpg")
+    assert got is False and calls == []  # never fetched
+    assert c.execute("SELECT image_url FROM articles WHERE id=1").fetchone()[0] == "http://existing/img.jpg"
+
+
+def test_enrich_records_checked_even_when_none_found(tmp_path):
+    c = _setup(tmp_path); _add(c, 1, image=None)
+    got = enrich.enrich_article_image(c, 1, fetch=lambda url: None)
+    assert got is False
+    # checked_at stamped → won't retry until the retry window passes
+    assert c.execute("SELECT image_checked_at FROM articles WHERE id=1").fetchone()[0] is not None
+    again = enrich.enrich_article_image(c, 1, fetch=lambda url: "http://late.jpg", retry_days=7)
+    assert again is False  # still within retry window
+
+
+def test_backfill_only_targets_summarized_accepted_imageless(tmp_path):
+    c = _setup(tmp_path)
+    _add(c, 1, image=None, summarized=True, accepted=1)   # eligible
+    _add(c, 2, image=None, summarized=False, accepted=1)  # no summary → skip
+    _add(c, 3, image=None, summarized=True, accepted=0)   # rejected → skip
+    _add(c, 4, image="http://has.jpg", summarized=True)   # has image → skip
+    n = enrich.enrich_summarized_images(c, fetch=lambda url: "http://og.jpg", limit=50)
+    assert n == 1
+    assert c.execute("SELECT image_url FROM articles WHERE id=2").fetchone()[0] is None