Adopt a peer's unmeasured faces instead of refusing them

The tablet showed a fraction of each person: 681 of the desktop's 3,851
confirmations, and none of Ian's 746, Catherine's 626 or my own 480.
Every face that existed on both devices agreed on who it was, and the
people rows were identical — the merge was fine. The missing 3,170
confirmations were on faces the tablet did not hold at all: the
desktop's 16,080 faces from the original detector, on 4,310 images,
detected before schema V14 kept the quality reading.

Those faces were in shards the tablet had already downloaded, in
August's export. `import_from_shards` looked at them on every sync pass
and declined each one, because a face without a quality reading was
"work this device cannot finish": adopting it would write the run
marker, and the marker was what stopped an image being looked at again.
That was true when it was written and has not been since the quality
repair existed — that pass lists its work by `f.quality IS NULL`, not by
the marker, exactly as the eye pass does, and faces without an eye
reading were already adopted on that reasoning.

The refusal had no exit. V14 had deleted the markers of every image
holding such faces so the quality pass would find them, and
`export_to_shards` walks the markers, so the desktop never re-exported
them either; the unmeasured August copies were the only ones there
would ever be. The tablet's answer was to queue all 17,727 images for a
re-detection of its own, a fetch of the whole library, while holding
the faces on disk.

Adopt them. The receiving device's quality pass measures them when it
reaches them, and the desktop's confirmations match onto them by box
overlap on the next catalog merge. The test that asserted the refusal
now asserts the adoption and that the image is still owed to the pass.

core/dr-catalog/src/face_shard.rs

@@ -820,20 +820,22 @@ pub fn import_from_shards(
         let Some((faces, edge)) = store.get_image(file_id as u64, &held)? else {
             continue;
         };
-        // A peer that embedded before the quality was kept has done work this
-        // device cannot finish: the number exists only at embedding time, and
-        // adopting the faces would write the run marker that keeps them from
-        // ever being measured (schema V14). Left for this device's own pass —
-        // or for the peer's, whose re-export replaces these.
+        // A face the peer embedded before its quality was kept (schema V14)
+        // is adopted with the reading missing, exactly as one without an eye
+        // reading is. The measuring passes find their work by the NULL
+        // column, not by the run marker (`dr_ui::repairs`, `faces_needing`),
+        // so adopting costs the reading nothing and this device's own pass
+        // fills it.
         //
-        // A missing *eye* reading is not the same case and is adopted. The
-        // measuring pass finds those by the NULL, not by the marker, so
-        // adopting the faces costs the reading nothing (schema V16) — and a
-        // peer that has no eye models may be the only one that has done the
-        // detection at all.
-        if faces.iter().any(|f| f.quality.is_none()) {
-            continue;
-        }
+        // This used to refuse such faces, on the reasoning that the marker
+        // would stop them ever being measured — true before the quality
+        // repair existed, and wrong after. What it cost: V14 had dropped the
+        // markers of every image holding such faces, so the peer never
+        // re-exported them, and the only copies in the shards were the
+        // unmeasured ones. A tablet holding shards with 4,310 of the
+        // desktop's images and 3,170 of its confirmations declined every one
+        // of them, showed a fraction of each person, and queued the whole
+        // library for a re-detection of its own instead.
         let local: Vec<crate::faces::DetectedFace> = faces
             .into_iter()
             .map(|f| crate::faces::DetectedFace {
@@ -1365,11 +1367,12 @@ mod catalog_round_trip {
         );
     }
 
-    /// A face a peer embedded without measuring it is work this device
-    /// cannot finish, and adopting it would write the marker that stops it
-    /// ever being measured. The image stays outstanding instead.
+    /// A face a peer embedded without measuring it is adopted all the same,
+    /// and left on this device's quality pass by its missing reading. Refusing
+    /// it was what stranded every confirmation the desktop had made on faces
+    /// from before V14: the tablet held the shards and would not use them.
     #[test]
-    fn a_peers_unmeasured_faces_are_left_for_this_device_to_index() {
+    fn a_peers_unmeasured_faces_are_adopted_and_left_for_the_quality_pass() {
         let b = device(&[(90, 5001), (91, 5002)]);
         let mut store = FaceShardStore::open(&tempdir("unmeasured")).unwrap();
         let shared = |file_id: u64, quality: Option<f32>| SharedFace {
@@ -1395,13 +1398,18 @@ mod catalog_round_trip {
             .put_image(5002, "w600k_mbf", 2560, &[shared(5002, Some(19.0))])
             .unwrap();
 
-        assert_eq!(import_from_shards(&b, &store, "w600k_mbf").unwrap(), 1);
+        assert_eq!(import_from_shards(&b, &store, "w600k_mbf").unwrap(), 2);
         let cov = faces::coverage(&b, "w600k_mbf").unwrap();
-        assert_eq!(cov.indexed, 1);
-        assert_eq!(cov.outstanding(), 1, "the unmeasured image was adopted");
-        assert!(faces::for_image(&b, dr_types::ImageId(90))
-            .unwrap()
-            .is_empty());
+        assert_eq!(cov.indexed, 2);
+        assert_eq!(cov.outstanding(), 0, "the unmeasured image was refused");
+        let got = faces::for_image(&b, dr_types::ImageId(90)).unwrap();
+        assert_eq!(got.len(), 1);
+        assert_eq!(got[0].quality, None, "a reading was invented");
+        // Still owed to the measuring pass, which lists by the column.
+        assert_eq!(
+            faces::count_needing(&b, "w600k_mbf", "f.quality IS NULL").unwrap(),
+            1
+        );
     }
 
     #[test]