Introduce following for assistant panel (#14479)

Release Notes:

- Added support for following into the assistant panel.

---------

Co-authored-by: Max <max@zed.dev>
Co-authored-by: Max Brunsfeld <maxbrunsfeld@gmail.com>
Co-authored-by: Nathan <nathan@zed.dev>

crates/workspace/src/dock.rs

@@ -1,6 +1,7 @@
 use crate::persistence::model::DockData;
 use crate::{status_bar::StatusItemView, Workspace};
-use crate::{DraggedDock, Event};
+use crate::{DraggedDock, Event, Pane};
+use client::proto;
 use gpui::{
     deferred, div, px, Action, AnchorCorner, AnyView, AppContext, Axis, Entity, EntityId,
     EventEmitter, FocusHandle, FocusableView, IntoElement, KeyContext, MouseButton, MouseDownEvent,
@@ -23,6 +24,8 @@ pub enum PanelEvent {
     Close,
 }
 
+pub use proto::PanelId;
+
 pub trait Panel: FocusableView + EventEmitter<PanelEvent> {
     fn persistent_name() -> &'static str;
     fn position(&self, cx: &WindowContext) -> DockPosition;
@@ -44,6 +47,12 @@ pub trait Panel: FocusableView + EventEmitter<PanelEvent> {
     }
     fn set_zoomed(&mut self, _zoomed: bool, _cx: &mut ViewContext<Self>) {}
     fn set_active(&mut self, _active: bool, _cx: &mut ViewContext<Self>) {}
+    fn pane(&self) -> Option<View<Pane>> {
+        None
+    }
+    fn remote_id() -> Option<proto::PanelId> {
+        None
+    }
 }
 
 pub trait PanelHandle: Send + Sync {
@@ -55,6 +64,8 @@ pub trait PanelHandle: Send + Sync {
     fn is_zoomed(&self, cx: &WindowContext) -> bool;
     fn set_zoomed(&self, zoomed: bool, cx: &mut WindowContext);
     fn set_active(&self, active: bool, cx: &mut WindowContext);
+    fn remote_id(&self) -> Option<proto::PanelId>;
+    fn pane(&self, cx: &WindowContext) -> Option<View<Pane>>;
     fn size(&self, cx: &WindowContext) -> Pixels;
     fn set_size(&self, size: Option<Pixels>, cx: &mut WindowContext);
     fn icon(&self, cx: &WindowContext) -> Option<ui::IconName>;
@@ -101,6 +112,14 @@ where
         self.update(cx, |this, cx| this.set_active(active, cx))
     }
 
+    fn pane(&self, cx: &WindowContext) -> Option<View<Pane>> {
+        self.read(cx).pane()
+    }
+
+    fn remote_id(&self) -> Option<PanelId> {
+        T::remote_id()
+    }
+
     fn size(&self, cx: &WindowContext) -> Pixels {
         self.read(cx).size(cx)
     }
@@ -296,6 +315,12 @@ impl Dock {
             .position(|entry| entry.panel.persistent_name() == ui_name)
     }
 
+    pub fn panel_index_for_proto_id(&self, panel_id: PanelId) -> Option<usize> {
+        self.panel_entries
+            .iter()
+            .position(|entry| entry.panel.remote_id() == Some(panel_id))
+    }
+
     pub fn active_panel_index(&self) -> usize {
         self.active_panel_index
     }

crates/workspace/src/item.rs

@@ -3,7 +3,7 @@ use crate::{
     persistence::model::ItemId,
     searchable::SearchableItemHandle,
     workspace_settings::{AutosaveSetting, WorkspaceSettings},
-    DelayedDebouncedEditAction, FollowableItemBuilders, ItemNavHistory, ToolbarItemLocation,
+    DelayedDebouncedEditAction, FollowableViewRegistry, ItemNavHistory, ToolbarItemLocation,
     ViewId, Workspace, WorkspaceId,
 };
 use anyhow::Result;
@@ -472,22 +472,6 @@ impl<T: Item> ItemHandle for View<T> {
             this.added_to_workspace(workspace, cx);
         });
 
-        if let Some(followed_item) = self.to_followable_item_handle(cx) {
-            if let Some(message) = followed_item.to_state_proto(cx) {
-                workspace.update_followers(
-                    followed_item.is_project_item(cx),
-                    proto::update_followers::Variant::CreateView(proto::View {
-                        id: followed_item
-                            .remote_id(&workspace.client(), cx)
-                            .map(|id| id.to_proto()),
-                        variant: Some(message),
-                        leader_id: workspace.leader_for_pane(&pane),
-                    }),
-                    cx,
-                );
-            }
-        }
-
         if workspace
             .panes_by_item
             .insert(self.item_id(), pane.downgrade())
@@ -548,11 +532,11 @@ impl<T: Item> ItemHandle for View<T> {
 
                     if let Some(item) = item.to_followable_item_handle(cx) {
                         let leader_id = workspace.leader_for_pane(&pane);
-                        let follow_event = item.to_follow_event(event);
-                        if leader_id.is_some()
-                            && matches!(follow_event, Some(FollowEvent::Unfollow))
-                        {
-                            workspace.unfollow(&pane, cx);
+
+                        if let Some(leader_id) = leader_id {
+                            if let Some(FollowEvent::Unfollow) = item.to_follow_event(event) {
+                                workspace.unfollow(leader_id, cx);
+                            }
                         }
 
                         if item.focus_handle(cx).contains_focused(cx) {
@@ -682,9 +666,7 @@ impl<T: Item> ItemHandle for View<T> {
     }
 
     fn to_followable_item_handle(&self, cx: &AppContext) -> Option<Box<dyn FollowableItemHandle>> {
-        let builders = cx.try_global::<FollowableItemBuilders>()?;
-        let item = self.to_any();
-        Some(builders.get(&item.entity_type())?.1(&item))
+        FollowableViewRegistry::to_followable_view(self.clone(), cx)
     }
 
     fn on_release(
@@ -769,11 +751,15 @@ pub enum FollowEvent {
     Unfollow,
 }
 
+pub enum Dedup {
+    KeepExisting,
+    ReplaceExisting,
+}
+
 pub trait FollowableItem: Item {
     fn remote_id(&self) -> Option<ViewId>;
     fn to_state_proto(&self, cx: &WindowContext) -> Option<proto::view::Variant>;
     fn from_state_proto(
-        pane: View<Pane>,
         project: View<Workspace>,
         id: ViewId,
         state: &mut Option<proto::view::Variant>,
@@ -794,6 +780,7 @@ pub trait FollowableItem: Item {
     ) -> Task<Result<()>>;
     fn is_project_item(&self, cx: &WindowContext) -> bool;
     fn set_leader_peer_id(&mut self, leader_peer_id: Option<PeerId>, cx: &mut ViewContext<Self>);
+    fn dedup(&self, existing: &Self, cx: &WindowContext) -> Option<Dedup>;
 }
 
 pub trait FollowableItemHandle: ItemHandle {
@@ -815,6 +802,7 @@ pub trait FollowableItemHandle: ItemHandle {
         cx: &mut WindowContext,
     ) -> Task<Result<()>>;
     fn is_project_item(&self, cx: &WindowContext) -> bool;
+    fn dedup(&self, existing: &dyn FollowableItemHandle, cx: &WindowContext) -> Option<Dedup>;
 }
 
 impl<T: FollowableItem> FollowableItemHandle for View<T> {
@@ -868,6 +856,11 @@ impl<T: FollowableItem> FollowableItemHandle for View<T> {
     fn is_project_item(&self, cx: &WindowContext) -> bool {
         self.read(cx).is_project_item(cx)
     }
+
+    fn dedup(&self, existing: &dyn FollowableItemHandle, cx: &WindowContext) -> Option<Dedup> {
+        let existing = existing.to_any().downcast::<T>().ok()?;
+        self.read(cx).dedup(existing.read(cx), cx)
+    }
 }
 
 pub trait WeakFollowableItemHandle: Send + Sync {

crates/workspace/src/pane_group.rs

@@ -1,6 +1,7 @@
 use crate::{pane_group::element::pane_axis, AppState, FollowerState, Pane, Workspace};
 use anyhow::{anyhow, Result};
 use call::{ActiveCall, ParticipantLocation};
+use client::proto::PeerId;
 use collections::HashMap;
 use gpui::{
     point, size, AnyView, AnyWeakView, Axis, Bounds, IntoElement, Model, MouseButton, Pixels,
@@ -95,7 +96,7 @@ impl PaneGroup {
     pub(crate) fn render(
         &self,
         project: &Model<Project>,
-        follower_states: &HashMap<View<Pane>, FollowerState>,
+        follower_states: &HashMap<PeerId, FollowerState>,
         active_call: Option<&Model<ActiveCall>>,
         active_pane: &View<Pane>,
         zoomed: Option<&AnyWeakView>,
@@ -168,7 +169,7 @@ impl Member {
         &self,
         project: &Model<Project>,
         basis: usize,
-        follower_states: &HashMap<View<Pane>, FollowerState>,
+        follower_states: &HashMap<PeerId, FollowerState>,
         active_call: Option<&Model<ActiveCall>>,
         active_pane: &View<Pane>,
         zoomed: Option<&AnyWeakView>,
@@ -181,19 +182,29 @@ impl Member {
                     return div().into_any();
                 }
 
-                let follower_state = follower_states.get(pane);
-
-                let leader = follower_state.and_then(|state| {
-                    let room = active_call?.read(cx).room()?.read(cx);
-                    room.remote_participant_for_peer_id(state.leader_id)
+                let follower_state = follower_states.iter().find_map(|(leader_id, state)| {
+                    if state.center_pane == *pane {
+                        Some((*leader_id, state))
+                    } else {
+                        None
+                    }
                 });
 
-                let is_in_unshared_view = follower_state.map_or(false, |state| {
+                let leader = follower_state.as_ref().and_then(|(leader_id, _)| {
+                    let room = active_call?.read(cx).room()?.read(cx);
+                    room.remote_participant_for_peer_id(*leader_id)
+                });
+
+                let is_in_unshared_view = follower_state.as_ref().map_or(false, |(_, state)| {
                     state.active_view_id.is_some_and(|view_id| {
                         !state.items_by_leader_view_id.contains_key(&view_id)
                     })
                 });
 
+                let is_in_panel = follower_state
+                    .as_ref()
+                    .map_or(false, |(_, state)| state.dock_pane.is_some());
+
                 let mut leader_border = None;
                 let mut leader_status_box = None;
                 let mut leader_join_data = None;
@@ -203,7 +214,11 @@ impl Member {
                         .players()
                         .color_for_participant(leader.participant_index.0)
                         .cursor;
-                    leader_color.fade_out(0.3);
+                    if is_in_panel {
+                        leader_color.fade_out(0.75);
+                    } else {
+                        leader_color.fade_out(0.3);
+                    }
                     leader_border = Some(leader_color);
 
                     leader_status_box = match leader.location {
@@ -483,7 +498,7 @@ impl PaneAxis {
         &self,
         project: &Model<Project>,
         basis: usize,
-        follower_states: &HashMap<View<Pane>, FollowerState>,
+        follower_states: &HashMap<PeerId, FollowerState>,
         active_call: Option<&Model<ActiveCall>>,
         active_pane: &View<Pane>,
         zoomed: Option<&AnyWeakView>,