Panics · P13 Lists: a directory selection gone from its entries picks none

src/lists/directory.rs

@@ -152,11 +152,17 @@ impl DirectoryListing {
     /// The entry picked, by name.
     pub fn selected(mut self, name: impl Into<SharedString>) -> Self {
         let name = name.into();
-        assert!(
-            self.entries.iter().any(|entry| entry.name == name),
-            "no entry {name}"
-        );
-        self.selected = Some(name);
+        self.selected = self
+            .entries
+            .iter()
+            .any(|entry| entry.name == name)
+            .then(|| name.clone());
+        if self.selected.is_none() {
+            log::error!(
+                "directory listing {:?}: no entry {name}; none picked",
+                self.id
+            );
+        }
         self
     }
 
@@ -350,7 +356,16 @@ impl RenderOnce for DirectoryListing {
 mod tests {
     use jiff::Timestamp;
 
-    use super::{Column, DirEntry, sorted};
+    use super::{Column, DirEntry, DirectoryListing, sorted};
+
+    #[test]
+    fn a_selected_name_gone_from_the_entries_picks_none() {
+        let entries = || [DirEntry::file("a.txt", 1, Timestamp::UNIX_EPOCH)];
+        let gone = DirectoryListing::new("dir", ["home"], entries()).selected("b.txt");
+        assert_eq!(gone.selected, None);
+        let kept = DirectoryListing::new("dir", ["home"], entries()).selected("a.txt");
+        assert_eq!(kept.selected.as_deref(), Some("a.txt"));
+    }
 
     fn names(entries: Vec<DirEntry>) -> Vec<String> {
         entries

tasks/panics.md

@@ -27,7 +27,7 @@ Each item reads every site in its folders, fixes what the rules name, updates ca
 - [x] P10 Feedback — `src/feedback`
 - [x] P11 Loading & Motion — `src/motion`
 - [x] P12 Data Display — `src/data_display`
-- [ ] P13 Lists & Trees — `src/lists`
+- [x] P13 Lists & Trees — `src/lists`
 - [ ] P14 Tables — `src/tables`
 - [ ] P15 Charts — `src/charts`
 - [ ] P16 Finance — `src/finance`
@@ -77,3 +77,4 @@ One line per item: what changed, what stayed and why, review rounds.
 - P10: no change. Kept: a toast's stay above zero (one value). Review: 1 round.
 - P11: a buffer at or behind the value draws none; `slide` was fixed in P05. Kept: values in 0..=1, segment and skeleton counts (one value each), builder misuse, reorder's permutation. Review: 1 round.
 - P12: a featured column past the columns features none; a gauge past its scale pegs; usage parts past the total fill it and repeat hues past eight; stars above max log and fill. Kept: one-value contracts, a comparison row's shape, construction. Review: 3 rounds (round 2 met an edit that had not applied).
+- P13: a directory listing's selected name gone from its entries picks none. Kept: one-value contracts; activation, folder split, single-select sections and tree rows hold by construction. Review: 1 round.