assistant: Insert creases for tool uses (#17330)

This PR makes it so we create creases for each of the tool uses in the
context editor.

<img width="1290" alt="Screenshot 2024-09-03 at 5 37 33 PM"
src="https://github.com/user-attachments/assets/94e943fd-3f05-4bc4-9672-94bff42ec500">

Release Notes:

- N/A

crates/assistant/src/assistant_panel.rs

@@ -1416,6 +1416,7 @@ pub struct ContextEditor {
     remote_id: Option<workspace::ViewId>,
     pending_slash_command_creases: HashMap<Range<language::Anchor>, CreaseId>,
     pending_slash_command_blocks: HashMap<Range<language::Anchor>, CustomBlockId>,
+    pending_tool_use_creases: HashMap<Range<language::Anchor>, CreaseId>,
     _subscriptions: Vec<Subscription>,
     workflow_steps: HashMap<Range<language::Anchor>, WorkflowStepViewState>,
     active_workflow_step: Option<ActiveWorkflowStep>,
@@ -1480,6 +1481,7 @@ impl ContextEditor {
             project,
             pending_slash_command_creases: HashMap::default(),
             pending_slash_command_blocks: HashMap::default(),
+            pending_tool_use_creases: HashMap::default(),
             _subscriptions,
             workflow_steps: HashMap::default(),
             active_workflow_step: None,
@@ -1855,6 +1857,72 @@ impl ContextEditor {
                             cx,
                         );
                     }
+
+                    let new_tool_uses = self
+                        .context
+                        .read(cx)
+                        .pending_tool_uses()
+                        .into_iter()
+                        .filter(|tool_use| {
+                            !self
+                                .pending_tool_use_creases
+                                .contains_key(&tool_use.source_range)
+                        })
+                        .cloned()
+                        .collect::<Vec<_>>();
+
+                    let buffer = editor.buffer().read(cx).snapshot(cx);
+                    let (excerpt_id, _buffer_id, _) = buffer.as_singleton().unwrap();
+                    let excerpt_id = *excerpt_id;
+
+                    let mut buffer_rows_to_fold = BTreeSet::new();
+
+                    let creases = new_tool_uses
+                        .iter()
+                        .map(|tool_use| {
+                            let placeholder = FoldPlaceholder {
+                                render: render_fold_icon_button(
+                                    cx.view().downgrade(),
+                                    IconName::PocketKnife,
+                                    tool_use.name.clone().into(),
+                                ),
+                                constrain_width: false,
+                                merge_adjacent: false,
+                            };
+                            let render_trailer =
+                                move |_row, _unfold, _cx: &mut WindowContext| Empty.into_any();
+
+                            let start = buffer
+                                .anchor_in_excerpt(excerpt_id, tool_use.source_range.start)
+                                .unwrap();
+                            let end = buffer
+                                .anchor_in_excerpt(excerpt_id, tool_use.source_range.end)
+                                .unwrap();
+
+                            let buffer_row = MultiBufferRow(start.to_point(&buffer).row);
+                            buffer_rows_to_fold.insert(buffer_row);
+
+                            Crease::new(
+                                start..end,
+                                placeholder,
+                                fold_toggle("tool-use"),
+                                render_trailer,
+                            )
+                        })
+                        .collect::<Vec<_>>();
+
+                    let crease_ids = editor.insert_creases(creases, cx);
+
+                    for buffer_row in buffer_rows_to_fold.into_iter().rev() {
+                        editor.fold_at(&FoldAt { buffer_row }, cx);
+                    }
+
+                    self.pending_tool_use_creases.extend(
+                        new_tool_uses
+                            .iter()
+                            .map(|tool_use| tool_use.source_range.clone())
+                            .zip(crease_ids),
+                    );
                 });
             }
             ContextEvent::WorkflowStepsUpdated { removed, updated } => {