fix(tui): stabilize history ordering and scrollback

code-rs/Cargo.lock

@@ -1559,6 +1559,7 @@ dependencies = [
  "regex-lite",
  "reqwest",
  "serde",
+ "serde_bytes",
  "serde_json",
  "sha2",
  "shlex",

code-rs/tui/Cargo.toml

@@ -18,6 +18,7 @@ debug-logs = []
 dev-faults = []
 # Fork-specific extensions layered on top of upstream history rendering.
 code-fork = []
+test-helpers = []
 
 [lints]
 workspace = true
@@ -112,6 +113,7 @@ insta = "1.43.1"
 pretty_assertions = "1"
 rand = "0.9"
 strip-ansi-escapes = "0.1"
+serde_bytes = "0.11"
 [build-dependencies]
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"

code-rs/tui/src/chatwidget.rs

@@ -74,7 +74,7 @@ mod terminal_handlers;
 mod terminal;
 mod tools;
 mod running_tools;
-#[cfg(test)]
+#[cfg(any(test, feature = "test-helpers"))]
 pub mod smoke_helpers;
 use self::agent_install::{
     start_agent_install_session,
@@ -5366,6 +5366,18 @@ impl ChatWidget<'_> {
         if !is_reasoning_cell {
             self.clear_reasoning_in_progress();
         }
+        let is_background_cell = matches!(cell.kind(), HistoryCellType::BackgroundEvent);
+        let mut key = key;
+        let mut key_bumped = false;
+        if !is_background_cell {
+            if let Some(last) = self.last_assigned_order {
+                if key <= last {
+                    key = Self::order_key_successor(last);
+                    key_bumped = true;
+                }
+            }
+        }
+
         // Determine insertion position across the entire history
         let mut pos = self.history_cells.len();
         for i in 0..self.history_cells.len() {
@@ -5521,6 +5533,15 @@ impl ChatWidget<'_> {
             );
         }
         self.cell_order_seq.insert(pos, key);
+        if key_bumped {
+            if let Some(stream) = self.history_cells[pos]
+                .as_any()
+                .downcast_ref::<crate::history_cell::StreamingContentCell>()
+            {
+                self.stream_order_seq
+                    .insert((StreamKind::Answer, stream.state().stream_id.clone()), key);
+            }
+        }
         self.last_assigned_order = Some(match self.last_assigned_order {
             Some(prev) => prev.max(key),
             None => key,
@@ -5571,7 +5592,7 @@ impl ChatWidget<'_> {
     fn history_insert_existing_record(
         &mut self,
         mut cell: Box<dyn HistoryCell>,
-        key: OrderKey,
+        mut key: OrderKey,
         tag: &'static str,
         id: HistoryId,
     ) -> usize {
@@ -5592,7 +5613,18 @@ impl ChatWidget<'_> {
             .downcast_ref::<crate::history_cell::CollapsibleReasoningCell>()
             .is_some();
         if !is_reasoning_cell {
-            self.clear_reasoning_in_progress();
+                self.clear_reasoning_in_progress();
+        }
+
+        let is_background_cell = matches!(cell.kind(), HistoryCellType::BackgroundEvent);
+        let mut key_bumped = false;
+        if !is_background_cell {
+            if let Some(last) = self.last_assigned_order {
+                if key <= last {
+                    key = Self::order_key_successor(last);
+                    key_bumped = true;
+                }
+            }
         }
 
         let mut pos = self.history_cells.len();
@@ -5683,6 +5715,15 @@ impl ChatWidget<'_> {
             );
         }
         self.cell_order_seq.insert(pos, key);
+        if key_bumped {
+            if let Some(stream) = self.history_cells[pos]
+                .as_any()
+                .downcast_ref::<crate::history_cell::StreamingContentCell>()
+            {
+                self.stream_order_seq
+                    .insert((StreamKind::Answer, stream.state().stream_id.clone()), key);
+            }
+        }
         self.last_assigned_order = Some(match self.last_assigned_order {
             Some(prev) => prev.max(key),
             None => key,
@@ -15704,7 +15745,7 @@ fi\n\
             "final-answer: ordered insert new AssistantMarkdownCell id={:?}",
             id
         );
-        let key = match id.as_deref() {
+        let mut key = match id.as_deref() {
             Some(rid) => self
                 .try_stream_order_key(StreamKind::Answer, rid)
                 .unwrap_or_else(|| {
@@ -15719,6 +15760,18 @@ fi\n\
                 self.next_internal_key()
             }
         };
+        if let Some(last) = self.last_assigned_order {
+            if key <= last {
+                // Background notices anchor themselves at out = i32::MAX. If a final answer arrives
+                // after those notices we still want it to appear at the bottom, so bump the key
+                // just past the most-recently assigned slot.
+                key = Self::order_key_successor(last);
+                if let Some(ref want) = id {
+                    self.stream_order_seq
+                        .insert((StreamKind::Answer, want.clone()), key);
+                }
+            }
+        }
         tracing::info!(
             "[order] final Answer ordered insert id={:?} {}",
             id,
@@ -18854,6 +18907,445 @@ fi\n\
     }
 }
 
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::chatwidget::smoke_helpers::ChatWidgetHarness;
+    use crate::history_cell::HistoryCellType;
+    use code_core::history::state::{
+        AssistantStreamDelta,
+        AssistantStreamState,
+        InlineSpan,
+        MessageLine,
+        MessageLineKind,
+        PlainMessageKind,
+        PlainMessageRole,
+        PlainMessageState,
+        TextEmphasis,
+        TextTone,
+    };
+    use code_core::protocol::OrderMeta;
+    use ratatui::backend::TestBackend;
+    use ratatui::text::Line;
+    use ratatui::Terminal;
+    use std::time::SystemTime;
+
+    fn reset_history(chat: &mut ChatWidget<'_>) {
+        chat.history_cells.clear();
+        chat.history_cell_ids.clear();
+        chat.history_state = HistoryState::new();
+        chat.history_render.invalidate_all();
+        chat.cell_order_seq.clear();
+        chat.cell_order_dbg.clear();
+        chat.ui_background_seq_counters.clear();
+        chat.last_assigned_order = None;
+        chat.last_seen_request_index = 0;
+        chat.current_request_index = 0;
+        chat.internal_seq = 0;
+        chat.synthetic_system_req = None;
+        chat.layout.scroll_offset = 0;
+        chat.layout.last_max_scroll.set(0);
+        chat.layout.last_history_viewport_height.set(0);
+    }
+
+    fn insert_plain_cell(chat: &mut ChatWidget<'_>, lines: &[&str]) {
+        use code_core::history::state::{
+            InlineSpan,
+            MessageLine,
+            MessageLineKind,
+            PlainMessageKind,
+            PlainMessageRole,
+            PlainMessageState,
+            TextEmphasis,
+            TextTone,
+        };
+
+        let state = PlainMessageState {
+            id: HistoryId::ZERO,
+            role: PlainMessageRole::System,
+            kind: PlainMessageKind::Plain,
+            header: None,
+            lines: lines
+                .iter()
+                .map(|text| MessageLine {
+                    kind: MessageLineKind::Paragraph,
+                    spans: vec![InlineSpan {
+                        text: (*text).to_string(),
+                        tone: TextTone::Default,
+                        emphasis: TextEmphasis::default(),
+                        entity: None,
+                    }],
+                })
+                .collect(),
+            metadata: None,
+        };
+
+        let key = chat.next_internal_key();
+        let _ = chat.history_insert_plain_state_with_key(state, key, "test");
+    }
+
+    #[test]
+    fn ordering_keeps_new_answers_after_prior_backgrounds() {
+        let mut harness = ChatWidgetHarness::new();
+        let chat = harness.chat();
+        reset_history(chat);
+
+        chat.last_seen_request_index = 1;
+        chat.current_request_index = 1;
+        chat.internal_seq = 0;
+
+        chat.push_background_tail("background-one".to_string());
+        chat.push_background_tail("background-two".to_string());
+
+        assert_eq!(chat.history_cells.len(), 2, "expected two background cells");
+
+        let answer_id = "answer-turn-1";
+        let seeded_key = OrderKey {
+            req: 1,
+            out: 1,
+            seq: 0,
+        };
+        chat.seed_stream_order_key(StreamKind::Answer, answer_id, seeded_key);
+
+        let response_text = "assistant-response";
+        chat.insert_final_answer_with_id(
+            Some(answer_id.to_string()),
+            vec![Line::from(response_text)],
+            response_text.to_string(),
+        );
+
+        assert_eq!(chat.history_cells.len(), 3, "expected assistant cell to be added");
+
+        let tail_kinds: Vec<HistoryCellType> = chat
+            .history_cells
+            .iter()
+            .map(|cell| cell.kind())
+            .collect();
+
+        let len = tail_kinds.len();
+        assert_eq!(
+            &tail_kinds[len - 3..],
+            &[
+                HistoryCellType::BackgroundEvent,
+                HistoryCellType::BackgroundEvent,
+                HistoryCellType::Assistant,
+            ],
+            "assistant output should appear after existing background cells",
+        );
+    }
+
+    #[test]
+    fn scrollback_spacer_preserves_top_cell_bottom_line() {
+        let mut harness = ChatWidgetHarness::new();
+        let chat = harness.chat();
+        reset_history(chat);
+
+        insert_plain_cell(chat, &["old-1", "old-2"]);
+        insert_plain_cell(chat, &["mid-1", "mid-2"]);
+        insert_plain_cell(chat, &["new-1", "new-2"]);
+
+        let viewport_height = 6;
+        chat.layout.scroll_offset = 2;
+
+        let mut terminal = Terminal::new(TestBackend::new(40, viewport_height)).expect("terminal");
+        terminal
+            .draw(|frame| frame.render_widget_ref(&*chat, frame.area()))
+            .expect("draw history");
+
+        let adjusted = chat.history_render.adjust_scroll_to_content(2);
+        assert_eq!(adjusted, 1, "scroll origin should step back from spacer row");
+
+        let prefix = chat.history_render.prefix_sums.borrow();
+        assert!(!prefix.is_empty(), "prefix sums populated after draw");
+        let start_idx = match prefix.binary_search(&adjusted) {
+            Ok(i) => i,
+            Err(i) => i.saturating_sub(1),
+        };
+        assert_eq!(start_idx, 0, "expected first cell to be visible after adjustment");
+
+        let content_y = prefix[start_idx];
+        drop(prefix);
+        let skip_top = adjusted.saturating_sub(content_y);
+        assert_eq!(skip_top, 1, "should display the second line of the oldest cell");
+
+        let cell = &chat.history_cells[start_idx];
+        let lines = cell.display_lines_trimmed();
+        let line = lines
+            .get(skip_top as usize)
+            .expect("line available after scroll adjustment");
+        let text: String = line.spans.iter().map(|span| span.content.as_ref()).collect();
+        assert_eq!(text.trim(), "old-2");
+    }
+
+    #[test]
+    fn scrollback_spacer_exact_offset_adjusts_to_content() {
+        let mut harness = ChatWidgetHarness::new();
+        let chat = harness.chat();
+        reset_history(chat);
+
+        insert_plain_cell(chat, &["old-1", "old-2"]);
+        insert_plain_cell(chat, &["mid-1", "mid-2"]);
+        insert_plain_cell(chat, &["new-1", "new-2"]);
+
+        let viewport_height = 6;
+        chat.layout.scroll_offset = 2;
+
+        {
+            let mut terminal =
+                Terminal::new(TestBackend::new(40, viewport_height)).expect("terminal");
+            terminal
+                .draw(|frame| frame.render_widget_ref(&*chat, frame.area()))
+                .expect("draw history");
+        }
+
+        let ranges = chat.history_render.spacing_ranges_for_test();
+        let (pos, _) = ranges
+            .first()
+            .copied()
+            .expect("expected a spacer-induced adjustment");
+        let adjusted = chat.history_render.adjust_scroll_to_content(pos);
+        assert!(
+            adjusted < pos,
+            "scroll adjustment should reduce the origin when landing on a spacer"
+        );
+    }
+
+    #[test]
+    fn scrollback_top_boundary_retains_oldest_content() {
+        let mut harness = ChatWidgetHarness::new();
+        let chat = harness.chat();
+        reset_history(chat);
+
+        insert_plain_cell(chat, &["old-1", "old-2"]);
+        insert_plain_cell(chat, &["mid-1", "mid-2"]);
+        insert_plain_cell(chat, &["new-1", "new-2"]);
+
+        {
+            let mut terminal = Terminal::new(TestBackend::new(40, 6)).expect("terminal");
+            terminal
+                .draw(|frame| frame.render_widget_ref(&*chat, frame.area()))
+                .expect("draw history");
+        }
+
+        let max_scroll = chat.layout.last_max_scroll.get();
+        assert!(max_scroll > 0, "expected overflow to produce a positive max scroll");
+        chat.layout.scroll_offset = max_scroll;
+
+        let mut terminal = Terminal::new(TestBackend::new(40, 6)).expect("terminal");
+        terminal
+            .draw(|frame| frame.render_widget_ref(&*chat, frame.area()))
+            .expect("draw history at top boundary");
+
+        let max_scroll = chat.layout.last_max_scroll.get();
+        let scroll_from_top = max_scroll.saturating_sub(chat.layout.scroll_offset);
+        let effective = chat.history_render.adjust_scroll_to_content(scroll_from_top);
+        let prefix = chat.history_render.prefix_sums.borrow();
+        let mut start_idx = match prefix.binary_search(&effective) {
+            Ok(i) => i,
+            Err(i) => i.saturating_sub(1),
+        };
+        start_idx = start_idx.min(prefix.len().saturating_sub(1));
+        start_idx = start_idx.min(chat.history_cells.len().saturating_sub(1));
+        let content_y = prefix[start_idx];
+        drop(prefix);
+
+        let skip = effective.saturating_sub(content_y) as usize;
+        let cell = &chat.history_cells[start_idx];
+        let lines = cell.display_lines_trimmed();
+        let target_index = skip.min(lines.len().saturating_sub(1));
+        let visible = lines
+            .get(target_index)
+            .map(|line| {
+                line.spans
+                    .iter()
+                    .map(|span| span.content.as_ref())
+                    .collect::<String>()
+            })
+            .unwrap_or_default();
+
+        assert!(
+            visible.contains("old-1"),
+            "scrolling to the top should keep the oldest content visible"
+        );
+    }
+
+    #[test]
+    fn ordering_stream_delta_should_follow_existing_background_tail() {
+        let mut harness = ChatWidgetHarness::new();
+        let chat = harness.chat();
+        reset_history(chat);
+
+        chat.last_seen_request_index = 1;
+        chat.push_background_tail("background".to_string());
+
+        let stream_state = AssistantStreamState {
+            id: HistoryId::ZERO,
+            stream_id: "stream-1".into(),
+            preview_markdown: "partial".into(),
+            deltas: vec![AssistantStreamDelta {
+                delta: "partial".into(),
+                sequence: Some(0),
+                received_at: SystemTime::now(),
+            }],
+            citations: vec![],
+            metadata: None,
+            in_progress: true,
+            last_updated_at: SystemTime::now(),
+        };
+        let stream_cell = history_cell::new_streaming_content(stream_state, &chat.config);
+
+        chat.history_insert_with_key_global_tagged(
+            Box::new(stream_cell),
+            OrderKey {
+                req: 1,
+                out: 0,
+                seq: 0,
+            },
+            "stream",
+            None,
+        );
+
+        let kinds: Vec<HistoryCellType> = chat
+            .history_cells
+            .iter()
+            .map(|cell| cell.kind())
+            .collect();
+
+        assert_eq!(
+            kinds,
+            vec![HistoryCellType::BackgroundEvent, HistoryCellType::Assistant],
+            "streaming assistant output should append after the existing background tail cell",
+        );
+    }
+
+    #[test]
+    fn ordering_tool_reasoning_explore_should_preserve_arrival_sequence() {
+        let mut harness = ChatWidgetHarness::new();
+        let chat = harness.chat();
+        reset_history(chat);
+
+        chat.last_seen_request_index = 1;
+
+        let make_plain = |text: &str| PlainMessageState {
+            id: HistoryId::ZERO,
+            role: PlainMessageRole::System,
+            kind: PlainMessageKind::Plain,
+            header: None,
+            lines: vec![MessageLine {
+                kind: MessageLineKind::Paragraph,
+                spans: vec![InlineSpan {
+                    text: text.to_string(),
+                    tone: TextTone::Default,
+                    emphasis: TextEmphasis::default(),
+                    entity: None,
+                }],
+            }],
+            metadata: None,
+        };
+
+        // Reasoning arrives first with later output index.
+        let reasoning_key = ChatWidget::order_key_from_order_meta(&OrderMeta {
+            request_ordinal: 1,
+            output_index: Some(2),
+            sequence_number: Some(0),
+        });
+        chat.history_insert_plain_state_with_key(make_plain("reasoning"), reasoning_key, "reasoning");
+
+        // Explore summary follows immediately afterwards.
+        let explore_key = ChatWidget::order_key_from_order_meta(&OrderMeta {
+            request_ordinal: 1,
+            output_index: Some(3),
+            sequence_number: Some(0),
+        });
+        chat.history_insert_plain_state_with_key(make_plain("explore"), explore_key, "explore");
+
+        // Tool run summary arrives last but references an earlier output index.
+        let tool_key = ChatWidget::order_key_from_order_meta(&OrderMeta {
+            request_ordinal: 1,
+            output_index: Some(1),
+            sequence_number: Some(0),
+        });
+        chat.history_insert_plain_state_with_key(make_plain("tool"), tool_key, "tool");
+
+        let labels: Vec<String> = chat
+            .history_cells
+            .iter()
+            .map(|cell| {
+                cell.display_lines_trimmed()
+                    .first()
+                    .map(|line| line.spans.iter().map(|span| span.content.as_ref()).collect())
+                    .unwrap_or_default()
+            })
+            .collect();
+
+        assert_eq!(
+            labels,
+            vec!["reasoning".to_string(), "explore".to_string(), "tool".to_string()],
+            "later inserts with smaller output_index should not leapfrog visible reasoning/explore summaries",
+        );
+    }
+
+    #[test]
+    fn ordering_cross_request_pre_prompt_should_not_prepend_previous_turn() {
+        let mut harness = ChatWidgetHarness::new();
+        let chat = harness.chat();
+        reset_history(chat);
+
+        let make_plain = |text: &str| PlainMessageState {
+            id: HistoryId::ZERO,
+            role: PlainMessageRole::System,
+            kind: PlainMessageKind::Plain,
+            header: None,
+            lines: vec![MessageLine {
+                kind: MessageLineKind::Paragraph,
+                spans: vec![InlineSpan {
+                    text: text.to_string(),
+                    tone: TextTone::Default,
+                    emphasis: TextEmphasis::default(),
+                    entity: None,
+                }],
+            }],
+            metadata: None,
+        };
+
+        chat.history_insert_plain_state_with_key(
+            make_plain("req1"),
+            OrderKey {
+                req: 1,
+                out: 0,
+                seq: 0,
+            },
+            "req1",
+        );
+
+        chat.last_seen_request_index = 1;
+        chat.pending_user_prompts_for_next_turn = 0;
+
+        let key = chat.system_order_key(SystemPlacement::PrePromptInCurrent, None);
+        chat.history_insert_plain_state_with_key(make_plain("system"), key, "system");
+
+        let labels: Vec<String> = chat
+            .history_cells
+            .iter()
+            .map(|cell| {
+                cell.display_lines_trimmed()
+                    .first()
+                    .map(|line| line.spans.iter().map(|span| span.content.as_ref()).collect())
+                    .unwrap_or_default()
+            })
+            .collect();
+
+        assert_eq!(
+            labels,
+            vec!["req1".to_string(), "system".to_string()],
+            "pre-prompt system notices for a new request should append after the prior turn rather than prepending it",
+        );
+    }
+
+
+
+}
+
 fn append_thought_ellipsis(text: &str) -> String {
     let trimmed = text.trim_end();
     if trimmed.ends_with('…') {
@@ -23260,6 +23752,7 @@ impl WidgetRef for &ChatWidget<'_> {
             prefix.push(0);
             let mut acc = 0u16;
             let content_width = content_area.width.saturating_sub(GUTTER_WIDTH);
+            let mut spacing_ranges: Vec<(u16, u16)> = Vec::new();
 
             for (idx, vis) in cells.iter().enumerate() {
                 let cell = vis.cell.expect("rendered cell missing source");
@@ -23303,7 +23796,10 @@ impl WidgetRef for &ChatWidget<'_> {
                     }
                 }
                 if should_add_spacing {
+                    let spacing_start = acc;
                     acc = acc.saturating_add(spacing);
+                    // Track the spacer interval so scroll adjustments can skip over it later.
+                    spacing_ranges.push((spacing_start, acc));
                 }
                 prefix.push(acc);
             }
@@ -23316,6 +23812,7 @@ impl WidgetRef for &ChatWidget<'_> {
             }
             self.history_render
                 .update_prefix_cache(content_area.width, prefix, total_height, cells.len());
+            self.history_render.update_spacing_ranges(spacing_ranges);
             rendered_cells_full = Some(cells);
         }
 
@@ -23362,7 +23859,13 @@ impl WidgetRef for &ChatWidget<'_> {
                 }
             }
 
-            (content_area.y, scroll_from_top)
+            // If our scroll origin landed on a spacer row between cells, nudge it up so
+            // the viewport starts with real content instead of an empty separator.
+            let adjusted_scroll_from_top = self
+                .history_render
+                .adjust_scroll_to_content(scroll_from_top);
+
+            (content_area.y, adjusted_scroll_from_top)
         };
 
         // Record current viewport height for the next frame

code-rs/tui/src/chatwidget/history_render.rs

@@ -37,6 +37,9 @@ pub(crate) struct HistoryRenderState {
     pub(crate) last_prefix_count: Cell<usize>,
     pub(crate) last_total_height: Cell<u16>,
     pub(crate) prefix_valid: Cell<bool>,
+    // Row intervals that correspond to inter-cell spacing so we can avoid
+    // landing the viewport on empty gaps when scrolling.
+    spacing_ranges: RefCell<Vec<(u16, u16)>>,
 }
 
 impl HistoryRenderState {
@@ -50,6 +53,7 @@ impl HistoryRenderState {
             last_prefix_count: Cell::new(0),
             last_total_height: Cell::new(0),
             prefix_valid: Cell::new(false),
+            spacing_ranges: RefCell::new(Vec::new()),
         }
     }
 
@@ -59,6 +63,7 @@ impl HistoryRenderState {
         self.prefix_sums.borrow_mut().clear();
         self.last_total_height.set(0);
         self.prefix_valid.set(false);
+        self.spacing_ranges.borrow_mut().clear();
     }
 
     pub(crate) fn handle_width_change(&self, width: u16) {
@@ -73,6 +78,7 @@ impl HistoryRenderState {
             self.last_total_height.set(0);
             self.prefix_valid.set(false);
             self.height_cache_last_width.set(width);
+            self.spacing_ranges.borrow_mut().clear();
         }
     }
 
@@ -89,6 +95,7 @@ impl HistoryRenderState {
         self.prefix_sums.borrow_mut().clear();
         self.last_total_height.set(0);
         self.prefix_valid.set(false);
+        self.spacing_ranges.borrow_mut().clear();
     }
 
     pub(crate) fn invalidate_all(&self) {
@@ -97,6 +104,7 @@ impl HistoryRenderState {
         self.prefix_sums.borrow_mut().clear();
         self.last_total_height.set(0);
         self.prefix_valid.set(false);
+        self.spacing_ranges.borrow_mut().clear();
     }
 
     pub(crate) fn should_rebuild_prefix(&self, width: u16, count: usize) -> bool {
@@ -129,6 +137,43 @@ impl HistoryRenderState {
         self.prefix_valid.set(true);
     }
 
+    pub(crate) fn update_spacing_ranges(&self, ranges: Vec<(u16, u16)>) {
+        *self.spacing_ranges.borrow_mut() = ranges;
+    }
+
+    pub(crate) fn adjust_scroll_to_content(&self, mut scroll_pos: u16) -> u16 {
+        if scroll_pos == 0 {
+            return scroll_pos;
+        }
+        let ranges = self.spacing_ranges.borrow();
+        if ranges.is_empty() {
+            return scroll_pos;
+        }
+        // Walk backwards until we hit a true cell row or run out of history.
+        loop {
+            let mut adjusted = false;
+            for &(start, end) in ranges.iter() {
+                if start == 0 {
+                    continue;
+                }
+                if scroll_pos >= start && scroll_pos < end {
+                    scroll_pos = start.saturating_sub(1);
+                    adjusted = true;
+                    break;
+                }
+            }
+            if !adjusted || scroll_pos == 0 {
+                break;
+            }
+        }
+        scroll_pos
+    }
+
+    #[cfg(test)]
+    pub(crate) fn spacing_ranges_for_test(&self) -> Vec<(u16, u16)> {
+        self.spacing_ranges.borrow().clone()
+    }
+
     pub(crate) fn last_total_height(&self) -> u16 {
         self.last_total_height.get()
     }

code-rs/tui/src/chatwidget/smoke_helpers.rs

@@ -4,10 +4,12 @@ use super::ChatWidget;
 use crate::app_event::AppEvent;
 use crate::app_event_sender::AppEventSender;
 use crate::tui::TerminalInfo;
+use code_core::history::state::HistoryRecord;
 use code_core::config::{Config, ConfigOverrides, ConfigToml};
 use code_core::protocol::Event;
 use once_cell::sync::Lazy;
 use std::sync::mpsc::{self, Receiver};
+use std::time::{Duration, Instant};
 use tokio::runtime::Runtime;
 
 static TEST_RUNTIME: Lazy<Runtime> = Lazy::new(|| {
@@ -60,7 +62,7 @@ impl ChatWidgetHarness {
         self.chat.handle_code_event(event);
     }
 
-    pub fn drain_events(&self) -> Vec<AppEvent> {
+    pub(crate) fn drain_events(&self) -> Vec<AppEvent> {
         let mut out = Vec::new();
         while let Ok(ev) = self.events.try_recv() {
             out.push(ev);
@@ -68,9 +70,41 @@ impl ChatWidgetHarness {
         out
     }
 
-    pub fn chat(&mut self) -> &mut ChatWidget<'static> {
+    pub(crate) fn chat(&mut self) -> &mut ChatWidget<'static> {
         &mut self.chat
     }
+
+    pub(crate) fn poll_until<F>(&mut self, mut predicate: F, timeout: Duration) -> Vec<AppEvent>
+    where
+        F: FnMut(&[AppEvent]) -> bool,
+    {
+        let deadline = Instant::now() + timeout;
+        let mut collected = Vec::new();
+
+        loop {
+            while let Ok(event) = self.events.try_recv() {
+                if !matches!(event, AppEvent::RequestRedraw) {
+                    collected.push(event);
+                }
+            }
+
+            if predicate(&collected) {
+                break;
+            }
+
+            if Instant::now() >= deadline {
+                break;
+            }
+
+            std::thread::sleep(Duration::from_millis(5));
+        }
+
+        collected
+    }
+
+    pub(crate) fn history_records(&self) -> Vec<HistoryRecord> {
+        self.chat.history_state.records.clone()
+    }
 }
 
 pub fn assert_has_insert_history(events: &[AppEvent]) {

code-rs/tui/src/lib.rs

@@ -101,6 +101,94 @@ pub use cli::Cli;
 pub use self::markdown_render::render_markdown_text;
 pub use public_widgets::composer_input::{ComposerAction, ComposerInput};
 
+#[cfg(feature = "test-helpers")]
+pub mod test_helpers {
+    pub use crate::chatwidget::smoke_helpers::ChatWidgetHarness;
+
+    use crate::app_event::AppEvent;
+    use code_core::history::state::HistoryRecord;
+    use std::time::Duration;
+
+    pub fn assert_has_terminal_chunk_containing(
+        harness: &mut ChatWidgetHarness,
+        needle: &str,
+    ) {
+        let events = harness.poll_until(
+            |events| {
+                events.iter().any(|event| {
+                    match event {
+                        AppEvent::TerminalChunk { chunk, .. } => {
+                            String::from_utf8_lossy(chunk).contains(needle)
+                        }
+                        _ => false,
+                    }
+                })
+            },
+            Duration::from_millis(200),
+        );
+        crate::chatwidget::smoke_helpers::assert_has_terminal_chunk_containing(&events, needle);
+    }
+
+    pub fn assert_has_background_event_containing(
+        harness: &mut ChatWidgetHarness,
+        needle: &str,
+    ) {
+        let events = harness.poll_until(
+            |events| {
+                events.iter().any(|event| {
+                    match event {
+                        AppEvent::InsertBackgroundEvent { message, .. } => {
+                            message.contains(needle)
+                        }
+                        _ => false,
+                    }
+                })
+            },
+            Duration::from_millis(200),
+        );
+        crate::chatwidget::smoke_helpers::assert_has_background_event_containing(&events, needle);
+    }
+
+    pub fn assert_has_codex_event(harness: &mut ChatWidgetHarness) {
+        let events = harness.poll_until(
+            |events| events
+                .iter()
+                .any(|event| matches!(event, AppEvent::CodexEvent(_))),
+            Duration::from_millis(200),
+        );
+        crate::chatwidget::smoke_helpers::assert_has_codex_event(&events);
+    }
+
+    pub fn assert_has_insert_history(harness: &mut ChatWidgetHarness) {
+        let events = harness.poll_until(
+            |events| {
+                events.iter().any(|event| {
+                    matches!(
+                        event,
+                        AppEvent::InsertHistory(_)
+                            | AppEvent::InsertHistoryWithKind { .. }
+                            | AppEvent::InsertFinalAnswer { .. }
+                    )
+                })
+            },
+            Duration::from_millis(200),
+        );
+        crate::chatwidget::smoke_helpers::assert_has_insert_history(&events);
+    }
+
+    pub fn assert_no_events(harness: &mut ChatWidgetHarness) {
+        let events = harness.poll_until(
+            |events| !events.is_empty(),
+            Duration::from_millis(100),
+        );
+        crate::chatwidget::smoke_helpers::assert_no_events(&events);
+    }
+
+    pub fn history_records(harness: &ChatWidgetHarness) -> Vec<HistoryRecord> {
+        harness.history_records()
+    }
+}
+
 fn theme_configured_in_config_file(code_home: &std::path::Path) -> bool {
     let config_path = code_home.join("config.toml");
     let Ok(contents) = std::fs::read_to_string(&config_path) else {

code-rs/tui/tests/ui_smoke.rs

@@ -13,6 +13,7 @@ use code_core::history::state::{
     HistoryRecord,
     HistoryState,
     MessageMetadata,
+    PatchEventType,
 };
 use code_core::protocol::{
     AgentMessageDeltaEvent,
@@ -34,14 +35,7 @@ use code_core::protocol::{
     OrderMeta,
     TokenUsage,
 };
-use code_tui::app_event::AppEvent;
-use code_tui::chatwidget::smoke_helpers::{
-    assert_has_background_event_containing,
-    assert_has_codex_event,
-    assert_has_insert_history,
-    assert_has_terminal_chunk_containing,
-    ChatWidgetHarness,
-};
+use code_tui::test_helpers::ChatWidgetHarness;
 use code_tui::{Cli, ComposerAction, ComposerInput};
 use crossterm::event::{KeyCode, KeyEvent, KeyModifiers};
 use mcp_types::CallToolResult;
@@ -470,7 +464,11 @@ fn smoke_exec_command_stream() {
             cwd: PathBuf::from("/tmp"),
             parsed_cmd: Vec::new(),
         }),
-        order: None,
+        order: Some(OrderMeta {
+            request_ordinal: 1,
+            output_index: Some(0),
+            sequence_number: Some(0),
+        }),
     });
 
     harness.handle_event(Event {
@@ -481,7 +479,11 @@ fn smoke_exec_command_stream() {
             stream: ExecOutputStream::Stdout,
             chunk: ByteBuf::from(vec![b'h', b'i', b'\n']),
         }),
-        order: None,
+        order: Some(OrderMeta {
+            request_ordinal: 1,
+            output_index: Some(0),
+            sequence_number: Some(1),
+        }),
     });
 
     harness.handle_event(Event {
@@ -494,11 +496,29 @@ fn smoke_exec_command_stream() {
             exit_code: 0,
             duration: Duration::from_millis(20),
         }),
-        order: None,
+        order: Some(OrderMeta {
+            request_ordinal: 1,
+            output_index: Some(0),
+            sequence_number: Some(2),
+        }),
     });
 
-    let events = harness.drain_events();
-    assert_has_terminal_chunk_containing(&events, "hi");
+    let records = code_tui::test_helpers::history_records(&harness);
+    let exec_record = records
+        .into_iter()
+        .find_map(|record| match record {
+            HistoryRecord::Exec(record) if record.call_id.as_deref() == Some(&call_id) => Some(record),
+            _ => None,
+        })
+        .expect("exec record present");
+
+    assert_eq!(exec_record.exit_code, Some(0), "exec exit code should be success");
+    let stdout = exec_record
+        .stdout_chunks
+        .iter()
+        .map(|chunk| chunk.content.as_str())
+        .collect::<String>();
+    assert_eq!(stdout, "hi\n", "stdout should include streamed content");
 }
 
 #[test]
@@ -521,11 +541,36 @@ fn smoke_approval_flow() {
             reason: Some("Apply change".into()),
             grant_root: None,
         }),
-        order: None,
+        order: Some(OrderMeta {
+            request_ordinal: 1,
+            output_index: Some(1),
+            sequence_number: Some(0),
+        }),
     });
 
-    let events = harness.drain_events();
-    assert_has_background_event_containing(&events, "sample.txt");
+    let records = code_tui::test_helpers::history_records(&harness);
+    let patch_record = records
+        .into_iter()
+        .find_map(|record| match record {
+            HistoryRecord::Patch(record) => Some(record),
+            _ => None,
+        })
+        .expect("patch approval record present");
+
+    assert!(
+        matches!(patch_record.patch_type, PatchEventType::ApprovalRequest),
+        "expected approval request patch cell"
+    );
+    let change = patch_record
+        .changes
+        .get(&PathBuf::from("sample.txt"))
+        .expect("change for sample.txt present");
+    match change {
+        FileChange::Add { content } => {
+            assert_eq!(content, "Hello world", "patch change should include file contents");
+        }
+        other => panic!("expected FileChange::Add, got {other:?}"),
+    }
 }
 
 #[test]
@@ -539,7 +584,11 @@ fn smoke_custom_tool_call() {
             tool_name: "browser_navigate".into(),
             parameters: Some(json!({ "url": "https://example.com" })),
         }),
-        order: None,
+        order: Some(OrderMeta {
+            request_ordinal: 1,
+            output_index: Some(1),
+            sequence_number: Some(0),
+        }),
     });
 
     harness.handle_event(Event {
@@ -552,11 +601,14 @@ fn smoke_custom_tool_call() {
             duration: Duration::from_millis(40),
             result: Ok("ok".into()),
         }),
-        order: None,
+        order: Some(OrderMeta {
+            request_ordinal: 1,
+            output_index: Some(1),
+            sequence_number: Some(1),
+        }),
     });
 
-    let events = harness.drain_events();
-    assert_has_codex_event(&events);
+    code_tui::test_helpers::assert_has_codex_event(&mut harness);
 }
 
 #[test]
@@ -575,7 +627,11 @@ fn smoke_mcp_tool_invocation() {
             call_id: "mcp-1".into(),
             invocation: invocation.clone(),
         }),
-        order: None,
+        order: Some(OrderMeta {
+            request_ordinal: 1,
+            output_index: Some(1),
+            sequence_number: Some(0),
+        }),
     });
 
     harness.handle_event(Event {
@@ -588,14 +644,17 @@ fn smoke_mcp_tool_invocation() {
             result: Ok(CallToolResult {
                 content: Vec::new(),
                 is_error: Some(false),
-                _meta: None,
+                structured_content: None,
             }),
         }),
-        order: None,
+        order: Some(OrderMeta {
+            request_ordinal: 1,
+            output_index: Some(1),
+            sequence_number: Some(1),
+        }),
     });
 
-    let events = harness.drain_events();
-    assert_has_codex_event(&events);
+    code_tui::test_helpers::assert_has_codex_event(&mut harness);
 }
 
 #[test]
@@ -607,7 +666,11 @@ fn smoke_streaming_assistant_message() {
         msg: EventMsg::AgentMessageDelta(AgentMessageDeltaEvent {
             delta: "Hello".into(),
         }),
-        order: None,
+        order: Some(OrderMeta {
+            request_ordinal: 1,
+            output_index: Some(0),
+            sequence_number: Some(0),
+        }),
     });
 
     harness.handle_event(Event {
@@ -616,7 +679,11 @@ fn smoke_streaming_assistant_message() {
         msg: EventMsg::AgentMessageDelta(AgentMessageDeltaEvent {
             delta: " world".into(),
         }),
-        order: None,
+        order: Some(OrderMeta {
+            request_ordinal: 1,
+            output_index: Some(0),
+            sequence_number: Some(1),
+        }),
     });
 
     harness.handle_event(Event {
@@ -625,9 +692,12 @@ fn smoke_streaming_assistant_message() {
         msg: EventMsg::AgentMessage(AgentMessageEvent {
             message: "Hello world".into(),
         }),
-        order: None,
+        order: Some(OrderMeta {
+            request_ordinal: 1,
+            output_index: Some(0),
+            sequence_number: Some(2),
+        }),
     });
 
-    let events = harness.drain_events();
-    assert_has_insert_history(&events);
+    code_tui::test_helpers::assert_has_insert_history(&mut harness);
 }