diff --git a/codex-rs/tui/src/pager_overlay.rs b/codex-rs/tui/src/pager_overlay.rs
index 8bb78b0253..3a52f951d4 100644
--- a/codex-rs/tui/src/pager_overlay.rs
+++ b/codex-rs/tui/src/pager_overlay.rs
@@ -17,6 +17,10 @@
 
 mod scrolling;
 
+#[cfg(test)]
+#[path = "pager_overlay/highlight_tests.rs"]
+mod highlight_tests;
+
 use std::io::Result;
 use std::sync::Arc;
 
@@ -798,9 +802,22 @@ impl TranscriptOverlay {
     }
 
     pub(crate) fn set_highlight_cell(&mut self, cell: Option<usize>) {
-        let live_tail = self.take_live_tail_renderable();
+        let previous = self.highlight_cell;
         self.highlight_cell = cell;
-        self.rebuild_renderables(live_tail);
+        // Highlighting changes only these cells' styling. Keep the other renderables and their
+        // cached heights so moving between prompts does not lay out the entire transcript again.
+        if previous != cell {
+            for index in [previous, cell].into_iter().flatten() {
+                if let Some(history_cell) = self.cells.get(index) {
+                    self.view.renderables[index] = Self::render_cell(
+                        history_cell,
+                        index,
+                        self.highlight_cell,
+                        self.history_state,
+                    );
+                }
+            }
+        }
         if let Some(idx) = self.highlight_cell {
             self.view.scroll_chunk_into_view(idx);
         }
diff --git a/codex-rs/tui/src/pager_overlay/highlight_tests.rs b/codex-rs/tui/src/pager_overlay/highlight_tests.rs
new file mode 100644
index 0000000000..a3661013f5
--- /dev/null
+++ b/codex-rs/tui/src/pager_overlay/highlight_tests.rs
@@ -0,0 +1,144 @@
+//! Backtrack selection preserves unrelated layout caches and the complete rendered viewport.
+
+use super::*;
+use crate::history_cell::UserHistoryCell;
+use crate::keymap::RuntimeKeymap;
+use pretty_assertions::assert_eq;
+use std::sync::atomic::AtomicUsize;
+use std::sync::atomic::Ordering;
+
+#[derive(Debug)]
+struct MeasuredCell {
+    measurements: AtomicUsize,
+}
+
+impl HistoryCell for MeasuredCell {
+    fn display_lines(&self, _width: u16) -> Vec<Line<'static>> {
+        vec!["history".into()]
+    }
+
+    fn raw_lines(&self) -> Vec<Line<'static>> {
+        vec!["history".into()]
+    }
+
+    fn desired_transcript_height(&self, _width: u16) -> u16 {
+        self.measurements.fetch_add(1, Ordering::Relaxed);
+        1
+    }
+}
+
+#[test]
+fn moving_highlight_preserves_unaffected_height_caches() {
+    let cells: Vec<_> = (0..32)
+        .map(|_| {
+            Arc::new(MeasuredCell {
+                measurements: AtomicUsize::new(0),
+            })
+        })
+        .collect();
+    let mut overlay = TranscriptOverlay::new(
+        cells
+            .iter()
+            .map(|cell| cell.clone() as Arc<dyn HistoryCell>)
+            .collect(),
+        RuntimeKeymap::defaults().pager,
+    );
+    let mut area = Rect::new(
+        /*x*/ 0, /*y*/ 0, /*width*/ 40, /*height*/ 12,
+    );
+    overlay.render(area, &mut Buffer::empty(area));
+
+    for selection in [Some(30), Some(28), Some(28), None] {
+        overlay.set_highlight_cell(selection);
+        overlay.render(area, &mut Buffer::empty(area));
+    }
+
+    let measurements = || {
+        cells
+            .iter()
+            .map(|cell| cell.measurements.load(Ordering::Relaxed))
+            .collect::<Vec<_>>()
+    };
+    let mut expected = vec![1; cells.len()];
+    expected[28] = 3;
+    expected[30] = 3;
+    assert_eq!(measurements(), expected);
+
+    // Width changes still invalidate every cached height.
+    area.width = 24;
+    overlay.render(area, &mut Buffer::empty(area));
+    for count in &mut expected {
+        *count += 1;
+    }
+    assert_eq!(measurements(), expected);
+}
+
+#[test]
+fn moving_highlight_matches_full_rebuild_with_live_tail() {
+    let cells: Vec<Arc<dyn HistoryCell>> = ["first prompt", "second prompt"]
+        .into_iter()
+        .map(|message| {
+            Arc::new(UserHistoryCell {
+                message: message.to_string(),
+                text_elements: Vec::new(),
+                local_image_paths: Vec::new(),
+                remote_image_urls: Vec::new(),
+            }) as Arc<dyn HistoryCell>
+        })
+        .collect();
+    let mut actual = TranscriptOverlay::new(cells.clone(), RuntimeKeymap::defaults().pager);
+    let mut expected = TranscriptOverlay::new(cells, RuntimeKeymap::defaults().pager);
+    for overlay in [&mut actual, &mut expected] {
+        overlay.sync_live_tail(
+            /*width*/ 40,
+            Some(ActiveCellTranscriptKey {
+                revision: 1,
+                is_stream_continuation: false,
+                animation_tick: None,
+            }),
+            |_| Some(vec![HyperlinkLine::from("live tail")]),
+        );
+    }
+
+    for width in [40, 24, 40] {
+        for selection in [Some(0), Some(1), Some(1), None, Some(99), Some(0)] {
+            actual.set_highlight_cell(selection);
+            let tail = expected.take_live_tail_renderable();
+            expected.highlight_cell = selection;
+            expected.rebuild_renderables(tail);
+            if let Some(index) = selection {
+                expected.view.scroll_chunk_into_view(index);
+            }
+
+            let area = Rect::new(/*x*/ 0, /*y*/ 0, width, /*height*/ 12);
+            let mut actual_buffer = Buffer::empty(area);
+            let mut expected_buffer = Buffer::empty(area);
+            actual.render(area, &mut actual_buffer);
+            expected.render(area, &mut expected_buffer);
+            assert_eq!(actual_buffer, expected_buffer);
+            assert_eq!(actual.view.scroll_offset, expected.view.scroll_offset);
+        }
+    }
+
+    actual.set_highlight_cell(Some(1));
+    let area = Rect::new(
+        /*x*/ 0, /*y*/ 0, /*width*/ 40, /*height*/ 20,
+    );
+    let mut buffer = Buffer::empty(area);
+    actual.render(area, &mut buffer);
+    let content = (1..area.height - 4)
+        .map(|y| {
+            (0..area.width)
+                .map(|x| buffer[(x, y)].symbol())
+                .collect::<String>()
+        })
+        .map(|line| line.trim_end().to_string())
+        .filter(|line| !line.is_empty() && line != "~")
+        .collect::<Vec<_>>()
+        .join("\n");
+    insta::assert_snapshot!(content, @"
+    › first prompt
+    › second prompt
+    live tail
+    ");
+}