assistant2: Add live context type and use in message editor (#22865)

Release Notes:

- N/A

---------

Co-authored-by: Marshall Bowers <elliott.codes@gmail.com>
Co-authored-by: Marshall <marshall@zed.dev>

crates/assistant2/src/thread.rs

@@ -3,7 +3,7 @@ use std::sync::Arc;
 use anyhow::Result;
 use assistant_tool::ToolWorkingSet;
 use chrono::{DateTime, Utc};
-use collections::{HashMap, HashSet};
+use collections::{BTreeMap, HashMap, HashSet};
 use futures::future::Shared;
 use futures::{FutureExt as _, StreamExt as _};
 use gpui::{AppContext, EventEmitter, ModelContext, SharedString, Task};
@@ -17,7 +17,7 @@ use serde::{Deserialize, Serialize};
 use util::{post_inc, TryFutureExt as _};
 use uuid::Uuid;
 
-use crate::context::{attach_context_to_message, Context, ContextId};
+use crate::context::{attach_context_to_message, ContextId, ContextSnapshot};
 
 #[derive(Debug, Clone, Copy)]
 pub enum RequestKind {
@@ -64,7 +64,7 @@ pub struct Thread {
     pending_summary: Task<Option<()>>,
     messages: Vec<Message>,
     next_message_id: MessageId,
-    context: HashMap<ContextId, Context>,
+    context: BTreeMap<ContextId, ContextSnapshot>,
     context_by_message: HashMap<MessageId, Vec<ContextId>>,
     completion_count: usize,
     pending_completions: Vec<PendingCompletion>,
@@ -83,7 +83,7 @@ impl Thread {
             pending_summary: Task::ready(None),
             messages: Vec::new(),
             next_message_id: MessageId(0),
-            context: HashMap::default(),
+            context: BTreeMap::default(),
             context_by_message: HashMap::default(),
             completion_count: 0,
             pending_completions: Vec::new(),
@@ -131,7 +131,7 @@ impl Thread {
         &self.tools
     }
 
-    pub fn context_for_message(&self, id: MessageId) -> Option<Vec<Context>> {
+    pub fn context_for_message(&self, id: MessageId) -> Option<Vec<ContextSnapshot>> {
         let context = self.context_by_message.get(&id)?;
         Some(
             context
@@ -149,7 +149,7 @@ impl Thread {
     pub fn insert_user_message(
         &mut self,
         text: impl Into<String>,
-        context: Vec<Context>,
+        context: Vec<ContextSnapshot>,
         cx: &mut ModelContext<Self>,
     ) {
         let message_id = self.insert_message(Role::User, text, cx);