From b80d522f0ebb59e62aafeaf15a12211bb9aa63a0 Mon Sep 17 00:00:00 2001
From: Hunter Bown <hmbown@gmail.com>
Date: Thu, 7 May 2026 15:17:08 -0500
Subject: [PATCH] fix(tui): clear stale scrollbar drag state

---
 crates/tui/src/tui/app.rs      |  1 +
 crates/tui/src/tui/ui.rs       |  2 ++
 crates/tui/src/tui/ui/tests.rs | 32 ++++++++++++++++++++++++++++++++
 3 files changed, 35 insertions(+)

diff --git a/crates/tui/src/tui/app.rs b/crates/tui/src/tui/app.rs
index 5bdc88a3..d14a039c 100644
--- a/crates/tui/src/tui/app.rs
+++ b/crates/tui/src/tui/app.rs
@@ -2467,6 +2467,7 @@ impl App {
 
         self.viewport.pending_scroll_delta = 0;
         self.viewport.transcript_selection.clear();
+        self.viewport.transcript_scrollbar_dragging = false;
 
         self.viewport.last_transcript_area = None;
         self.viewport.last_transcript_top = 0;
diff --git a/crates/tui/src/tui/ui.rs b/crates/tui/src/tui/ui.rs
index 13aa6f3a..eb5c4d0f 100644
--- a/crates/tui/src/tui/ui.rs
+++ b/crates/tui/src/tui/ui.rs
@@ -7338,6 +7338,8 @@ fn handle_mouse_event(app: &mut App, mouse: MouseEvent) -> Vec<ViewEvent> {
             }
         }
         MouseEventKind::Down(MouseButton::Left) => {
+            app.viewport.transcript_scrollbar_dragging = false;
+
             if mouse_hits_rect(mouse, app.viewport.jump_to_latest_button_area) {
                 app.scroll_to_bottom();
                 return Vec::new();
diff --git a/crates/tui/src/tui/ui/tests.rs b/crates/tui/src/tui/ui/tests.rs
index 228a44d6..b9fa29e1 100644
--- a/crates/tui/src/tui/ui/tests.rs
+++ b/crates/tui/src/tui/ui/tests.rs
@@ -359,6 +359,38 @@ fn transcript_scrollbar_drag_maps_mouse_row_to_scroll_position() {
     assert!(!app.viewport.transcript_scrollbar_dragging);
 }
 
+#[test]
+fn new_left_down_clears_stale_transcript_scrollbar_drag() {
+    let mut app = create_test_app();
+    app.history = vec![HistoryCell::Assistant {
+        content: "alpha beta".to_string(),
+        streaming: false,
+    }];
+    app.resync_history_revisions();
+    app.viewport.last_transcript_area = Some(Rect {
+        x: 2,
+        y: 5,
+        width: 20,
+        height: 10,
+    });
+    app.viewport.last_transcript_visible = 10;
+    app.viewport.last_transcript_total = 110;
+    app.viewport.transcript_scrollbar_dragging = true;
+
+    let events = handle_mouse_event(
+        &mut app,
+        MouseEvent {
+            kind: MouseEventKind::Down(MouseButton::Left),
+            column: 3,
+            row: 5,
+            modifiers: KeyModifiers::NONE,
+        },
+    );
+
+    assert!(events.is_empty());
+    assert!(!app.viewport.transcript_scrollbar_dragging);
+}
+
 #[test]
 fn right_click_opens_context_menu() {
     let mut app = create_test_app();