Break ground on assistant2 (#21109)

This PR breaks ground on a new `assistant2` crate.

In order to see this new version of the assistant, both of the following
must be true:
1. The `assistant2` feature flag is enabled for your user
   - It is **not** currently enabled for all staff.
2. You are running a development build of Zed

The intent here is to enable the folks working on `assistant2` to
incrementally land work onto `main` without breaking use of the current
Assistant for anyone.

<img width="1136" alt="Screenshot 2024-11-23 at 10 46 08 AM"
src="https://github.com/user-attachments/assets/5723a13f-5be1-4486-9460-ead7329ba78e">

Release Notes:

- N/A

crates/zed/Cargo.toml

@@ -19,6 +19,7 @@ activity_indicator.workspace = true
 anyhow.workspace = true
 assets.workspace = true
 assistant.workspace = true
+assistant2.workspace = true
 async-watch.workspace = true
 audio.workspace = true
 auto_update.workspace = true

crates/zed/src/main.rs

@@ -406,6 +406,7 @@ fn main() {
             stdout_is_a_pty(),
             cx,
         );
+        assistant2::init(cx);
         assistant_hints::init(cx);
         repl::init(
             app_state.fs.clone(),

crates/zed/src/zed.rs

@@ -236,10 +236,29 @@ pub fn initialize_workspace(
                 .unwrap_or(true)
         });
 
+        let release_channel = ReleaseChannel::global(cx);
+        let assistant2_feature_flag = cx.wait_for_flag::<feature_flags::Assistant2FeatureFlag>();
+
         let prompt_builder = prompt_builder.clone();
         cx.spawn(|workspace_handle, mut cx| async move {
-            let assistant_panel =
-                assistant::AssistantPanel::load(workspace_handle.clone(), prompt_builder, cx.clone());
+            let is_assistant2_enabled = if cfg!(test) {
+                false
+            } else {
+                let is_assistant2_feature_flag_enabled = assistant2_feature_flag.await;
+                release_channel == ReleaseChannel::Dev && is_assistant2_feature_flag_enabled
+            };
+
+            let (assistant_panel, assistant2_panel) = if is_assistant2_enabled {
+                let assistant2_panel =
+                    assistant2::AssistantPanel::load(workspace_handle.clone(), cx.clone()).await?;
+
+                (None, Some(assistant2_panel))
+            } else {
+                let assistant_panel =
+                    assistant::AssistantPanel::load(workspace_handle.clone(), prompt_builder, cx.clone()).await?;
+
+                (Some(assistant_panel), None)
+            };
 
             let project_panel = ProjectPanel::load(workspace_handle.clone(), cx.clone());
             let outline_panel = OutlinePanel::load(workspace_handle.clone(), cx.clone());
@@ -257,7 +276,6 @@ pub fn initialize_workspace(
                 project_panel,
                 outline_panel,
                 terminal_panel,
-                assistant_panel,
                 channels_panel,
                 chat_panel,
                 notification_panel,
@@ -265,14 +283,20 @@ pub fn initialize_workspace(
                 project_panel,
                 outline_panel,
                 terminal_panel,
-                assistant_panel,
                 channels_panel,
                 chat_panel,
                 notification_panel,
             )?;
 
             workspace_handle.update(&mut cx, |workspace, cx| {
-                workspace.add_panel(assistant_panel, cx);
+                if let Some(assistant_panel) = assistant_panel {
+                    workspace.add_panel(assistant_panel, cx);
+                }
+
+                if let Some(assistant2_panel) = assistant2_panel {
+                    workspace.add_panel(assistant2_panel, cx);
+                }
+
                 workspace.add_panel(project_panel, cx);
                 workspace.add_panel(outline_panel, cx);
                 workspace.add_panel(terminal_panel, cx);