fix(dates): also clear implausible true instants with a good legacy date (#160)

The first #160 migration cleared rows whose legacy date_taken_source
was 'filename'. But the true-instant drain wrote only the new-contract
triple, so rows with a correct legacy date (e.g. an exiftool container
date) could still carry a filename-derived implausible year in
date_utc. Prod has three: VID_<counter> videos dated 2095 / 2229 / 8580
whose containers say 2016 / 2017.

Clear just the triple wherever date_utc is outside [1995, 2028) UTC;
backfill_utc_dates re-resolves it with the gated matcher, and the
frozen legacy pair is left alone. On prod those three are the only
rows with date_utc out of range.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

migrations/2026-10-17-000000_reresolve_implausible_utc_dates/down.sql

@@ -0,0 +1,3 @@
+-- Data fix only: the cleared instants were wrong and are re-resolved by the
+-- drain, so there is nothing to restore.
+SELECT 1;

migrations/2026-10-17-000000_reresolve_implausible_utc_dates/up.sql

@@ -0,0 +1,17 @@
+-- #160 follow-up. The first fix (2026-10-16 migration) cleared rows whose
+-- legacy `date_taken_source` was 'filename'. But the true-instant drain
+-- (#118) re-ran the resolver over rows with a correct legacy date (e.g. an
+-- exiftool container date) and wrote only the new-contract triple, so
+-- some rows carry a filename-derived implausible year in `date_utc` while
+-- their legacy pair says 'exiftool'. On prod: three VID_<counter> videos
+-- (years 2095, 2229, 8580) whose containers say 2016/2017.
+--
+-- Clear just the triple on any row whose true instant is outside
+-- [1995-01-01, 2028-01-01) UTC. `date_utc IS NULL` puts it back in
+-- `backfill_utc_dates`, which re-resolves it with the gated matcher; the
+-- legacy pair is left alone (it's frozen for rollback, and here correct).
+UPDATE image_exif
+SET date_utc = NULL,
+    camera_offset_minutes = NULL,
+    date_taken_tz_source = NULL
+WHERE date_utc < 788918400 OR date_utc >= 1830297600;

src/filename_audit.rs

@@ -495,18 +495,92 @@ mod tests {
         assert_eq!(rels, vec!["Screenshot_2014-06-01-20-44-50.png"]);
     }
 
-    #[test]
-    fn migration_clears_implausible_filename_dates_for_re_resolution() {
-        // Migrate up to just before the #160 data fix, seed rows as the
-        // old matcher left them, then apply it.
-        const FIX: &str = "reresolve_implausible_filename_dates";
+    /// A connection migrated up to (not including) the migration whose
+    /// name contains `name`, for seeding the state a data fix repairs.
+    fn conn_before_migration(name: &str) -> SqliteConnection {
         let mut conn = SqliteConnection::establish(":memory:").expect("in-memory sqlite");
         for m in conn.pending_migrations(DB_MIGRATIONS).expect("pending") {
-            if m.name().to_string().contains(FIX) {
+            if m.name().to_string().contains(name) {
                 break;
             }
             conn.run_migration(&*m).expect("migration");
         }
+        conn
+    }
+
+    #[test]
+    fn migration_clears_implausible_true_instants_but_keeps_legacy_dates() {
+        // The prod shape the first fix missed: a correct exiftool legacy
+        // date, with a filename-derived 2229 instant written by the drain.
+        let mut conn = conn_before_migration("reresolve_implausible_utc_dates");
+        seed_row(
+            &mut conn,
+            1,
+            "VID_22290524_080551_818.mp4",
+            Some(1_500_069_534),
+            Some("exiftool"),
+        );
+        seed_row(&mut conn, 1, "beach.jpg", Some(1_500_069_534), Some("exif"));
+        let set_utc = |conn: &mut SqliteConnection, path: &str, utc: i64| {
+            diesel::update(image_exif::table.filter(image_exif::rel_path.eq(path)))
+                .set((
+                    image_exif::date_utc.eq(utc),
+                    image_exif::camera_offset_minutes.eq(-300),
+                    image_exif::date_taken_tz_source.eq("assumed_server"),
+                ))
+                .execute(conn)
+                .unwrap();
+        };
+        set_utc(&mut conn, "VID_22290524_080551_818.mp4", 8_185_669_551);
+        set_utc(&mut conn, "beach.jpg", 1_500_069_534);
+
+        conn.run_pending_migrations(DB_MIGRATIONS)
+            .expect("fix migration");
+
+        type Row = (
+            String,
+            Option<i64>,
+            Option<String>,
+            Option<i64>,
+            Option<i32>,
+        );
+        let rows: Vec<Row> = image_exif::table
+            .select((
+                image_exif::rel_path,
+                image_exif::date_taken,
+                image_exif::date_taken_source,
+                image_exif::date_utc,
+                image_exif::camera_offset_minutes,
+            ))
+            .order(image_exif::rel_path)
+            .load(&mut conn)
+            .unwrap();
+        assert_eq!(
+            rows,
+            vec![
+                (
+                    "VID_22290524_080551_818.mp4".into(),
+                    Some(1_500_069_534),
+                    Some("exiftool".into()),
+                    None,
+                    None
+                ),
+                (
+                    "beach.jpg".into(),
+                    Some(1_500_069_534),
+                    Some("exif".into()),
+                    Some(1_500_069_534),
+                    Some(-300)
+                ),
+            ]
+        );
+    }
+
+    #[test]
+    fn migration_clears_implausible_filename_dates_for_re_resolution() {
+        // Migrate up to just before the #160 data fix, seed rows as the
+        // old matcher left them, then apply it.
+        let mut conn = conn_before_migration("reresolve_implausible_filename_dates");
         // 2229-05-24 08:05:51 and 1053-05-19 10:15:27 (wall-as-UTC), a
         // real 2014 filename date, and an fs_time row that isn't ours to
         // touch even though its date is odd.