Tag the judgement dispatch R7 and record which half of FR-CULL-13 is met

apply_judgement and apply_label carry TRACES: R7, the burst
representative callback FR-CULL-13 with a note that choosing it writes
the grouping and no verdict. The register's status for FR-CULL-13 says
the write-path test is met and the evidence chips are outstanding.
Traceability matrix regenerated.

ui/dr-ui/src/library_ui/ratings_keywords.rs

@@ -115,7 +115,7 @@ impl LabelGesture {
     }
 }
 
-/// TRACES: FR-CAT-5 | FR-CAT-13
+/// TRACES: FR-CAT-5 | FR-CAT-13 | R7
 /// Label a set of images: catalog first, in one transaction, then the grid,
 /// the chips and both sidecars — the order and the reasons of
 /// [`apply_judgement`].
@@ -376,8 +376,15 @@ fn keyword_summary(word: &str, changed: usize, selected: usize, assigning: bool)
     format!("{verb} “{word}” {preposition} {changed} of {selected}")
 }
 
+/// TRACES: R7 | FR-CULL-13
 /// Apply a judgement to a set of images: catalog first, then sidecars.
 ///
+/// The judgement dispatch: every rating and flag a person gives passes
+/// through here, from an `on_*` callback below, and nothing else calls it.
+/// `tools/traceability/src/verdicts.rs` holds that to a list — a call from
+/// anywhere else, and in particular from anything that computes evidence
+/// about a frame, fails `cargo test -p traceability`.
+///
 /// # Order matters
 ///
 /// The catalog is written **synchronously and first**, so the star appears
@@ -1075,10 +1082,13 @@ pub(super) fn wire_ratings_and_flags(
             });
     }
 
+    // TRACES: FR-CULL-5 | FR-CULL-13
     // Name the frame an open burst folds to (FR-CULL-5). The default is the
     // earliest of them, chosen because it is a fact about the clock and not a
     // judgement about the photograph; this is the photographer, who is the only
-    // one who knows which of the twelve is the keeper, saying otherwise.
+    // one who knows which of the twelve is the keeper, saying otherwise. The
+    // choice is a grouping, not a verdict: `bursts::choose` moves the badge
+    // and writes no rating, flag or label (FR-CULL-13).
     //
     // A repaint of the badges rather than a reload, which is what separates it
     // from folding a burst up: the grid's query returns the same rows either