feat(provenance): capture which archive an extracted image came from (#87)

Images pulled out of a .zip/.rar previously kept no record of WHICH archive
they came from — the member->archive link was computed during extraction and
discarded, leaving only image->post. So the provenance modal could only scope
attachments to the whole post, showing every archive a 'High Resolution Files'
bundle carried instead of the one a given file lives in.

- ImageProvenance.from_attachment_id: nullable FK -> post_attachment.id
  (SET NULL), migration 0055.
- importer: _import_archive stamps from_attachment_id on every member's
  provenance row for the post (new + superseded + deduped members), resolving
  the archive's own PostAttachment by (post, sha). Post-pass UPDATE, NULL-only
  and idempotent, so it doesn't touch the dedup/supersede branches and the
  backfill is safe to re-run. Nested members link to the outer stored archive.
- provenance_service.for_image: when the originating post's provenance row
  records from_attachment_id, return ONLY that archive; else fall back to the
  primary-post scoping from 068def2.
- ProvenancePanel: heading pluralizes ('Attachment' for a single file).
- Backfill: re-running reextract_archive_attachments (ArchiveReextractCard)
  routes through _import_archive and stamps existing rows — no new code.

Tests: capture stamps on fresh import, nested-archive attribution, per-post
archive on dedup; for_image filters to the containing archive; reextract
backfill stamps the link.

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

tests/test_importer_archive.py

@@ -164,6 +164,86 @@ def test_archive_all_deduped_is_benign_not_flagged(importer, import_layout):
     assert provs == 4  # 2 images × 2 posts (enrich-on-duplicate)
 
 
+def test_archive_members_record_containing_archive(importer, import_layout):
+    """Milestone #87: each extracted member's provenance row records the archive
+    PostAttachment it came out of, so provenance can show the one archive a file
+    lives inside."""
+    import_root, _ = import_layout
+    importer.settings.phash_threshold = 0
+    arc = import_root / "Bob" / "set.cbz"
+    arc.parent.mkdir(parents=True, exist_ok=True)
+    with zipfile.ZipFile(arc, "w") as zf:
+        zf.writestr("a.jpg", _split_bytes("v"))
+        zf.writestr("b.jpg", _split_bytes("h"))
+    arc.with_suffix(".cbz.json").write_text(json.dumps(
+        {"category": "patreon", "id": "777", "title": "Set"}))
+
+    importer.import_one(arc)
+    att = importer.session.execute(select(PostAttachment)).scalar_one()
+    provs = importer.session.execute(select(ImageProvenance)).scalars().all()
+    assert len(provs) == 2
+    assert all(p.from_attachment_id == att.id for p in provs)
+
+
+def test_nested_archive_member_records_outer_archive(importer, import_layout):
+    """Nested members link to the OUTER stored archive — the only one persisted
+    as a PostAttachment (the inner archive lives in a tempdir)."""
+    import_root, _ = import_layout
+    importer.settings.phash_threshold = 0
+    inner = io.BytesIO()
+    with zipfile.ZipFile(inner, "w") as zf:
+        zf.writestr("p1.jpg", _split_bytes("v"))
+        zf.writestr("p2.jpg", _split_bytes("h"))
+    arc = import_root / "Nessie" / "hr.cbz"
+    arc.parent.mkdir(parents=True, exist_ok=True)
+    with zipfile.ZipFile(arc, "w") as zf:
+        zf.writestr("chapter.zip", inner.getvalue())
+    arc.with_suffix(".cbz.json").write_text(json.dumps(
+        {"category": "patreon", "id": "900", "title": "HR Pack"}))
+
+    importer.import_one(arc)
+    att = importer.session.execute(select(PostAttachment)).scalar_one()
+    provs = importer.session.execute(select(ImageProvenance)).scalars().all()
+    assert len(provs) == 2
+    assert all(p.from_attachment_id == att.id for p in provs)
+
+
+def test_deduped_archive_member_records_each_posts_archive(importer, import_layout):
+    """A member re-shipped in a second post's archive gets its NEW provenance row
+    (for the second post) stamped with the SECOND archive — the UPDATE-of-existing
+    path the reextract backfill relies on. Each post's rows point at its own
+    archive."""
+    import_root, _ = import_layout
+    importer.settings.phash_threshold = 0
+    pv, ph = _split_bytes("v"), _split_bytes("h")
+    first = import_root / "Dup" / "a.cbz"
+    first.parent.mkdir(parents=True, exist_ok=True)
+    with zipfile.ZipFile(first, "w") as zf:
+        zf.writestr("a.jpg", pv)
+        zf.writestr("b.jpg", ph)
+    first.with_suffix(".cbz.json").write_text(json.dumps(
+        {"category": "patreon", "id": "111", "title": "First"}))
+    importer.import_one(first)
+
+    second = import_root / "Dup" / "b.cbz"  # different post, same two images
+    with zipfile.ZipFile(second, "w") as zf:
+        zf.writestr("a.jpg", pv)
+        zf.writestr("b.jpg", ph)
+    second.with_suffix(".cbz.json").write_text(json.dumps(
+        {"category": "patreon", "id": "222", "title": "Second"}))
+    importer.import_one(second)
+
+    posts = {p.external_post_id: p.id for p in
+             importer.session.execute(select(Post)).scalars().all()}
+    atts = {a.post_id: a.id for a in
+            importer.session.execute(select(PostAttachment)).scalars().all()}
+    provs = importer.session.execute(select(ImageProvenance)).scalars().all()
+    assert len(provs) == 4  # 2 images × 2 posts
+    for p in provs:
+        assert p.from_attachment_id == atts[p.post_id]
+    assert atts[posts["111"]] != atts[posts["222"]]
+
+
 def test_corrupt_archive_still_stored(importer, import_layout):
     import_root, _ = import_layout
     arc = import_root / "Bob" / "broken.zip"