fix: simplify revision diff selection into a flat list

Revisions still used ancestry lanes and placed author/date/bookmark metadata before the summary. Show short change IDs and summaries first, move metadata to a dimmed detail row, and remove the obsolete picker graph projection.

tests/unit/diff.rs

@@ -1688,75 +1688,6 @@ fn graph_state() -> DiffState {
     state
 }
 
-#[test]
-fn picker_graph_preserves_forks_merges_and_marks_filtered_ancestry() {
-    let mut state = graph_state();
-    let graph = state.picker_graph();
-    assert_eq!(graph.len(), 5);
-    assert_eq!(graph["merge"][1].trim_end(), "├─┐");
-    assert_eq!(graph["right"][1].trim_end(), "├─┘");
-    assert!(!graph.values().flatten().any(|prefix| prefix.contains('~')));
-    state.category = 1;
-    state.refilter();
-    assert_eq!(state.entries().len(), 3);
-    assert_eq!(
-        state
-            .graph_revision(state.entries().nth(1).unwrap())
-            .unwrap()
-            .0,
-        "merge"
-    );
-    assert!(matches!(
-        state.entries().nth(1).unwrap().target,
-        RevisionTarget::Bookmark { .. }
-    ));
-    state.category = 0;
-    state.query = "left root".into();
-    state.refilter();
-    assert!(state.picker_graph().is_empty());
-    assert_eq!(state.entries().len(), 1);
-    state.before = Some(state.catalog.as_ref().unwrap().entries[1].clone());
-    state.query = "right".into();
-    state.refilter();
-    assert_eq!(state.picker_graph().len(), 2);
-    assert!(state.picker_graph()["merge"][1].contains('~'));
-}
-
-#[test]
-fn graph_crossings_do_not_join_unrelated_ancestry() {
-    let mut state = DiffState::new();
-    let mut catalog = Catalog {
-        kind: RepoKind::Jujutsu,
-        entries: Vec::new(),
-        graph: Default::default(),
-        notice: None,
-    };
-    for (id, parents) in [
-        ("a", vec!["x"]),
-        ("b", vec!["y"]),
-        ("merge", vec!["x", "z"]),
-        ("x", vec![]),
-        ("y", vec![]),
-        ("z", vec![]),
-    ] {
-        catalog.entries.push(revision(
-            RevisionTarget::Commit(id.into()),
-            id,
-            "",
-            Category::Revisions,
-        ));
-        catalog.graph.insert(
-            id.into(),
-            RevisionGraph {
-                parents: parents.into_iter().map(String::from).collect(),
-                ..Default::default()
-            },
-        );
-    }
-    state.apply_result(1, Ok(Outcome::Catalog(catalog)));
-    assert_eq!(state.picker_graph()["merge"][1].trim_end(), "├─╪─┤");
-}
-
 #[test]
 fn before_identity_survives_query_and_category_without_duplicate_graph_nodes() {
     let mut state = graph_state();

tests/unit/tui.rs

@@ -3561,7 +3561,7 @@ fn checkout_picker_labels_follow_the_configured_stage() {
 }
 
 #[test]
-fn jj_picker_renders_graph_before_badge_and_compacts_without_losing_controls() {
+fn jj_revision_picker_keeps_summaries_and_before_visible_without_graph_lanes() {
     use crate::diff::{Category, RepoKind, Revision, RevisionGraph, RevisionTarget};
     let mut catalog = diff_catalog();
     catalog.kind = RepoKind::Jujutsu;
@@ -3582,10 +3582,10 @@ fn jj_picker_renders_graph_before_badge_and_compacts_without_losing_controls() {
                 change_id: change.into(),
                 description: format!("{change} description"),
                 parents: parent.into_iter().map(str::to_owned).collect(),
-                author: "alice".into(),
+                author: "An author whose name must not displace the summary".into(),
                 timestamp: "2026-10-23".into(),
                 bookmarks: if current {
-                    "main".into()
+                    "vl/fin-1441-1-ora-edi-recovery@origin".into()
                 } else {
                     String::new()
                 },
@@ -3606,10 +3606,16 @@ fn jj_picker_renders_graph_before_badge_and_compacts_without_losing_controls() {
     render_diff(&mut terminal, &diff, &mut panels);
     let text = screen_text(&terminal);
     assert!(text.contains("Choose After"));
-    assert!(text.contains("@"));
-    assert!(text.contains("change-a [Before] alice 2026-10-23 [main] aaaa1111"));
-    assert!(text.contains("change-a description"));
-    assert!(!text.contains("Before:"));
+    let summary = text
+        .lines()
+        .find(|line| line.contains("change-a description"))
+        .unwrap();
+    assert!(summary.contains("[Before]"), "{text}");
+    assert!(!summary.contains("An author"), "{text}");
+    assert!(
+        !text.contains('~') && !text.contains('○') && !text.contains('◆'),
+        "{text}"
+    );
     let buffer = terminal.backend().buffer();
     let selected_rows: Vec<_> = (0..buffer.area.height)
         .filter(|&y| (0..buffer.area.width).any(|x| buffer[(x, y)].bg == Color::Blue))