WIP

Co-authored-by: Antonio Scandurra <me@as-cii.com>

Cargo.lock

@@ -11,6 +11,7 @@ dependencies = [
  "agent-client-protocol",
  "anyhow",
  "buffer_diff",
+ "chrono",
  "collections",
  "editor",
  "env_logger 0.11.8",
@@ -191,10 +192,12 @@ version = "0.1.0"
 dependencies = [
  "acp_thread",
  "action_log",
+ "agent",
  "agent-client-protocol",
  "agent_servers",
  "agent_settings",
  "anyhow",
+ "assistant_context",
  "assistant_tool",
  "assistant_tools",
  "chrono",
@@ -208,6 +211,7 @@ dependencies = [
  "env_logger 0.11.8",
  "fs",
  "futures 0.3.31",
+ "git",
  "gpui",
  "gpui_tokio",
  "handlebars 4.5.0",
@@ -221,6 +225,7 @@ dependencies = [
  "log",
  "lsp",
  "open",
+ "parking_lot",
  "paths",
  "portable-pty",
  "pretty_assertions",
@@ -233,6 +238,7 @@ dependencies = [
  "serde_json",
  "settings",
  "smol",
+ "sqlez",
  "task",
  "tempfile",
  "terminal",
@@ -249,6 +255,7 @@ dependencies = [
  "workspace-hack",
  "worktree",
  "zlog",
+ "zstd",
 ]
 
 [[package]]

crates/acp_thread/Cargo.toml

@@ -21,6 +21,7 @@ agent-client-protocol.workspace = true
 agent.workspace = true
 anyhow.workspace = true
 buffer_diff.workspace = true
+chrono.workspace = true
 collections.workspace = true
 editor.workspace = true
 file_icons.workspace = true

crates/acp_thread/src/acp_thread.rs

@@ -6,11 +6,13 @@ mod terminal;
 pub use connection::*;
 pub use diff::*;
 pub use mention::*;
+use serde::{Deserialize, Serialize};
 pub use terminal::*;
 
 use action_log::ActionLog;
 use agent_client_protocol as acp;
 use anyhow::{Context as _, Result, anyhow};
+use chrono::{DateTime, Utc};
 use editor::Bias;
 use futures::{FutureExt, channel::oneshot, future::BoxFuture};
 use gpui::{AppContext, AsyncApp, Context, Entity, EventEmitter, SharedString, Task, WeakEntity};
@@ -537,9 +539,15 @@ impl ToolCallContent {
             acp::ToolCallContent::Content { content } => {
                 Self::ContentBlock(ContentBlock::new(content, &language_registry, cx))
             }
-            acp::ToolCallContent::Diff { diff } => {
-                Self::Diff(cx.new(|cx| Diff::from_acp(diff, language_registry, cx)))
-            }
+            acp::ToolCallContent::Diff { diff } => Self::Diff(cx.new(|cx| {
+                Diff::finalized(
+                    diff.path,
+                    diff.old_text,
+                    diff.new_text,
+                    language_registry,
+                    cx,
+                )
+            })),
         }
     }
 
@@ -658,6 +666,17 @@ impl PlanEntry {
     }
 }
 
+#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq, Hash)]
+pub struct AgentServerName(pub SharedString);
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct AcpThreadMetadata {
+    pub agent: AgentServerName,
+    pub id: acp::SessionId,
+    pub title: SharedString,
+    pub updated_at: DateTime<Utc>,
+}
+
 pub struct AcpThread {
     title: SharedString,
     entries: Vec<AgentThreadEntry>,
@@ -673,6 +692,7 @@ pub struct AcpThread {
 #[derive(Debug)]
 pub enum AcpThreadEvent {
     NewEntry,
+    TitleUpdated,
     EntryUpdated(usize),
     EntriesRemoved(Range<usize>),
     ToolAuthorizationRequired,
@@ -916,6 +936,12 @@ impl AcpThread {
         cx.emit(AcpThreadEvent::NewEntry);
     }
 
+    pub fn update_title(&mut self, title: SharedString, cx: &mut Context<Self>) -> Result<()> {
+        self.title = title;
+        cx.emit(AcpThreadEvent::TitleUpdated);
+        Ok(())
+    }
+
     pub fn update_tool_call(
         &mut self,
         update: impl Into<ToolCallUpdate>,
@@ -1641,7 +1667,7 @@ mod tests {
     use super::*;
     use anyhow::anyhow;
     use futures::{channel::mpsc, future::LocalBoxFuture, select};
-    use gpui::{AsyncApp, TestAppContext, WeakEntity};
+    use gpui::{App, AsyncApp, TestAppContext, WeakEntity};
     use indoc::indoc;
     use project::{FakeFs, Fs};
     use rand::Rng as _;
@@ -2311,7 +2337,7 @@ mod tests {
             self: Rc<Self>,
             project: Entity<Project>,
             _cwd: &Path,
-            cx: &mut gpui::App,
+            cx: &mut App,
         ) -> Task<gpui::Result<Entity<AcpThread>>> {
             let session_id = acp::SessionId(
                 rand::thread_rng()

crates/acp_thread/src/connection.rs

@@ -1,14 +1,16 @@
-use crate::AcpThread;
+use crate::{AcpThread, AcpThreadMetadata};
 use agent_client_protocol::{self as acp};
 use anyhow::Result;
 use collections::IndexMap;
+use futures::channel::mpsc::UnboundedReceiver;
 use gpui::{Entity, SharedString, Task};
 use project::Project;
+use serde::{Deserialize, Serialize};
 use std::{any::Any, error::Error, fmt, path::Path, rc::Rc, sync::Arc};
 use ui::{App, IconName};
 use uuid::Uuid;
 
-#[derive(Clone, Debug, Eq, PartialEq)]
+#[derive(Clone, Debug, Eq, PartialEq, Serialize, Deserialize)]
 pub struct UserMessageId(Arc<str>);
 
 impl UserMessageId {
@@ -62,6 +64,10 @@ pub trait AgentConnection {
         None
     }
 
+    fn history(self: Rc<Self>) -> Option<Rc<dyn AgentHistory>> {
+        None
+    }
+
     fn into_any(self: Rc<Self>) -> Rc<dyn Any>;
 }
 
@@ -79,6 +85,18 @@ pub trait AgentSessionResume {
     fn run(&self, cx: &mut App) -> Task<Result<acp::PromptResponse>>;
 }
 
+pub trait AgentHistory {
+    fn list_threads(&self, cx: &mut App) -> Task<Result<Vec<AcpThreadMetadata>>>;
+    fn observe_history(&self, cx: &mut App) -> UnboundedReceiver<AcpThreadMetadata>;
+    fn load_thread(
+        self: Rc<Self>,
+        _project: Entity<Project>,
+        _cwd: &Path,
+        _session_id: acp::SessionId,
+        _cx: &mut App,
+    ) -> Task<Result<Entity<AcpThread>>>;
+}
+
 #[derive(Debug)]
 pub struct AuthRequired;
 

crates/acp_thread/src/diff.rs

@@ -1,4 +1,3 @@
-use agent_client_protocol as acp;
 use anyhow::Result;
 use buffer_diff::{BufferDiff, BufferDiffSnapshot};
 use editor::{MultiBuffer, PathKey};
@@ -21,17 +20,13 @@ pub enum Diff {
 }
 
 impl Diff {
-    pub fn from_acp(
-        diff: acp::Diff,
+    pub fn finalized(
+        path: PathBuf,
+        old_text: Option<String>,
+        new_text: String,
         language_registry: Arc<LanguageRegistry>,
         cx: &mut Context<Self>,
     ) -> Self {
-        let acp::Diff {
-            path,
-            old_text,
-            new_text,
-        } = diff;
-
         let multibuffer = cx.new(|_cx| MultiBuffer::without_headers(Capability::ReadOnly));
 
         let new_buffer = cx.new(|cx| Buffer::local(new_text, cx));

crates/acp_thread/src/mention.rs

@@ -2,6 +2,7 @@ use agent::ThreadId;
 use anyhow::{Context as _, Result, bail};
 use file_icons::FileIcons;
 use prompt_store::{PromptId, UserPromptId};
+use serde::{Deserialize, Serialize};
 use std::{
     fmt,
     ops::Range,
@@ -11,7 +12,7 @@ use std::{
 use ui::{App, IconName, SharedString};
 use url::Url;
 
-#[derive(Clone, Debug, PartialEq, Eq)]
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
 pub enum MentionUri {
     File {
         abs_path: PathBuf,

crates/agent/src/history_store.rs

@@ -62,7 +62,7 @@ enum SerializedRecentOpen {
 
 pub struct HistoryStore {
     thread_store: Entity<ThreadStore>,
-    context_store: Entity<assistant_context::ContextStore>,
+    pub context_store: Entity<assistant_context::ContextStore>,
     recently_opened_entries: VecDeque<HistoryEntryId>,
     _subscriptions: Vec<gpui::Subscription>,
     _save_recently_opened_entries_task: Task<()>,

crates/agent/src/thread_store.rs

@@ -893,7 +893,7 @@ impl ThreadsDatabase {
 
         let needs_migration_from_heed = mdb_path.exists();
 
-        let connection = if *ZED_STATELESS {
+        let connection = if *ZED_STATELESS || cfg!(any(feature = "test-support", test)) {
             Connection::open_memory(Some("THREAD_FALLBACK_DB"))
         } else {
             Connection::open_file(&sqlite_path.to_string_lossy())

crates/agent2/Cargo.toml

@@ -17,6 +17,7 @@ action_log.workspace = true
 agent-client-protocol.workspace = true
 agent_servers.workspace = true
 agent_settings.workspace = true
+agent.workspace = true
 anyhow.workspace = true
 assistant_tool.workspace = true
 assistant_tools.workspace = true
@@ -26,6 +27,7 @@ collections.workspace = true
 context_server.workspace = true
 fs.workspace = true
 futures.workspace = true
+git.workspace = true
 gpui.workspace = true
 handlebars = { workspace = true, features = ["rust-embed"] }
 html_to_markdown.workspace = true
@@ -37,6 +39,7 @@ language_model.workspace = true
 language_models.workspace = true
 log.workspace = true
 open.workspace = true
+parking_lot.workspace = true
 paths.workspace = true
 portable-pty.workspace = true
 project.workspace = true
@@ -46,6 +49,7 @@ schemars.workspace = true
 serde.workspace = true
 serde_json.workspace = true
 settings.workspace = true
+sqlez.workspace = true
 smol.workspace = true
 task.workspace = true
 terminal.workspace = true
@@ -57,8 +61,12 @@ watch.workspace = true
 web_search.workspace = true
 which.workspace = true
 workspace-hack.workspace = true
+zstd.workspace = true
+assistant_context.workspace = true
 
 [dev-dependencies]
+agent = { workspace = true, "features" = ["test-support"] }
+acp_thread = { workspace = true, "features" = ["test-support"] }
 ctor.workspace = true
 client = { workspace = true, "features" = ["test-support"] }
 clock = { workspace = true, "features" = ["test-support"] }
@@ -66,6 +74,7 @@ context_server = { workspace = true, "features" = ["test-support"] }
 editor = { workspace = true, "features" = ["test-support"] }
 env_logger.workspace = true
 fs = { workspace = true, "features" = ["test-support"] }
+git = { workspace = true, "features" = ["test-support"] }
 gpui = { workspace = true, "features" = ["test-support"] }
 gpui_tokio.workspace = true
 language = { workspace = true, "features" = ["test-support"] }

crates/agent2/src/agent.rs

@@ -1,10 +1,12 @@
+use crate::native_agent_server::NATIVE_AGENT_SERVER_NAME;
 use crate::{
-    AgentResponseEvent, ContextServerRegistry, CopyPathTool, CreateDirectoryTool, DeletePathTool,
-    DiagnosticsTool, EditFileTool, FetchTool, FindPathTool, GrepTool, ListDirectoryTool,
-    MovePathTool, NowTool, OpenTool, ReadFileTool, TerminalTool, ThinkingTool, Thread,
-    ToolCallAuthorization, UserMessageContent, WebSearchTool, templates::Templates,
+    ContextServerRegistry, CopyPathTool, CreateDirectoryTool, DeletePathTool, DiagnosticsTool,
+    EditFileTool, FetchTool, FindPathTool, GrepTool, ListDirectoryTool, MovePathTool, NowTool,
+    OpenTool, ReadFileTool, TerminalTool, ThinkingTool, Thread, ThreadEvent, ToolCallAuthorization,
+    UserMessageContent, WebSearchTool, templates::Templates,
 };
-use acp_thread::AgentModelSelector;
+use crate::{ThreadsDatabase, generate_session_id};
+use acp_thread::{AcpThread, AcpThreadMetadata, AgentHistory, AgentModelSelector};
 use agent_client_protocol as acp;
 use agent_settings::AgentSettings;
 use anyhow::{Context as _, Result, anyhow};
@@ -15,7 +17,7 @@ use futures::{StreamExt, future};
 use gpui::{
     App, AppContext, AsyncApp, Context, Entity, SharedString, Subscription, Task, WeakEntity,
 };
-use language_model::{LanguageModel, LanguageModelProvider, LanguageModelRegistry};
+use language_model::{LanguageModel, LanguageModelProvider, LanguageModelRegistry, SelectedModel};
 use project::{Project, ProjectItem, ProjectPath, Worktree};
 use prompt_store::{
     ProjectContext, PromptId, PromptStore, RulesFileContext, UserRulesContext, WorktreeContext,
@@ -27,6 +29,7 @@ use std::collections::HashMap;
 use std::path::Path;
 use std::rc::Rc;
 use std::sync::Arc;
+use std::time::Duration;
 use util::ResultExt;
 
 const RULES_FILE_NAMES: [&'static str; 9] = [
@@ -41,6 +44,8 @@ const RULES_FILE_NAMES: [&'static str; 9] = [
     "GEMINI.md",
 ];
 
+const SAVE_THREAD_DEBOUNCE: Duration = Duration::from_millis(500);
+
 pub struct RulesLoadingError {
     pub message: SharedString,
 }
@@ -51,7 +56,8 @@ struct Session {
     thread: Entity<Thread>,
     /// The ACP thread that handles protocol communication
     acp_thread: WeakEntity<acp_thread::AcpThread>,
-    _subscription: Subscription,
+    save_task: Task<()>,
+    _subscriptions: Vec<Subscription>,
 }
 
 pub struct LanguageModels {
@@ -166,6 +172,8 @@ pub struct NativeAgent {
     models: LanguageModels,
     project: Entity<Project>,
     prompt_store: Option<Entity<PromptStore>>,
+    thread_database: Arc<ThreadsDatabase>,
+    history_watchers: Vec<mpsc::UnboundedSender<AcpThreadMetadata>>,
     fs: Arc<dyn Fs>,
     _subscriptions: Vec<Subscription>,
 }
@@ -184,6 +192,11 @@ impl NativeAgent {
             .update(|cx| Self::build_project_context(&project, prompt_store.as_ref(), cx))?
             .await;
 
+        let thread_database = cx
+            .update(|cx| ThreadsDatabase::connect(cx))?
+            .await
+            .map_err(|e| anyhow!(e))?;
+
         cx.new(|cx| {
             let mut subscriptions = vec![
                 cx.subscribe(&project, Self::handle_project_event),
@@ -208,16 +221,87 @@ impl NativeAgent {
                 context_server_registry: cx.new(|cx| {
                     ContextServerRegistry::new(project.read(cx).context_server_store(), cx)
                 }),
+                thread_database,
                 templates,
                 models: LanguageModels::new(cx),
                 project,
                 prompt_store,
                 fs,
+                history_watchers: Vec::new(),
                 _subscriptions: subscriptions,
             }
         })
     }
 
+    pub fn insert_session(
+        &mut self,
+        thread: Entity<Thread>,
+        acp_thread: Entity<AcpThread>,
+        cx: &mut Context<Self>,
+    ) {
+        let id = thread.read(cx).id().clone();
+        let weak_thread = acp_thread.downgrade();
+        self.sessions.insert(
+            id,
+            Session {
+                thread: thread.clone(),
+                acp_thread: weak_thread.clone(),
+                save_task: Task::ready(()),
+                _subscriptions: vec![
+                    cx.observe_release(&acp_thread, |this, acp_thread, _cx| {
+                        this.sessions.remove(acp_thread.session_id());
+                    }),
+                    cx.observe(&thread, move |this, thread, cx| {
+                        if let Some(response_stream) =
+                            thread.update(cx, |thread, cx| thread.generate_title_if_needed(cx))
+                        {
+                            NativeAgentConnection::handle_thread_events(
+                                response_stream,
+                                weak_thread.clone(),
+                                cx,
+                            )
+                            .detach_and_log_err(cx);
+                        }
+                        this.save_thread(thread.clone(), cx)
+                    }),
+                ],
+            },
+        );
+    }
+
+    fn save_thread(&mut self, thread_handle: Entity<Thread>, cx: &mut Context<Self>) {
+        let thread = thread_handle.read(cx);
+        let id = thread.id().clone();
+        let Some(session) = self.sessions.get_mut(&id) else {
+            return;
+        };
+
+        let thread = thread_handle.downgrade();
+        let thread_database = self.thread_database.clone();
+        session.save_task = cx.spawn(async move |this, cx| {
+            cx.background_executor().timer(SAVE_THREAD_DEBOUNCE).await;
+
+            let Some(task) = thread.update(cx, |thread, cx| thread.to_db(cx)).ok() else {
+                return;
+            };
+            let db_thread = task.await;
+            let metadata = thread_database
+                .save_thread(id.clone(), db_thread)
+                .await
+                .log_err();
+            if let Some(metadata) = metadata {
+                this.update(cx, |this, _| {
+                    for watcher in this.history_watchers.iter_mut() {
+                        watcher
+                            .unbounded_send(metadata.clone().to_acp(NATIVE_AGENT_SERVER_NAME))
+                            .log_err();
+                    }
+                })
+                .ok();
+            }
+        });
+    }
+
     pub fn models(&self) -> &LanguageModels {
         &self.models
     }
@@ -420,7 +504,7 @@ impl NativeAgent {
 
     fn handle_models_updated_event(
         &mut self,
-        _registry: Entity<LanguageModelRegistry>,
+        registry: Entity<LanguageModelRegistry>,
         _event: &language_model::Event,
         cx: &mut Context<Self>,
     ) {
@@ -435,9 +519,14 @@ impl NativeAgent {
                 if thread.model().is_none()
                     && let Some(model) = default_model.clone()
                 {
-                    thread.set_model(model);
+                    thread.set_model(model, cx);
                     cx.notify();
                 }
+                let summarization_model = registry
+                    .read(cx)
+                    .thread_summary_model()
+                    .map(|model| model.model.clone());
+                thread.set_summarization_model(summarization_model, cx);
             });
         }
     }
@@ -461,10 +550,7 @@ impl NativeAgentConnection {
         session_id: acp::SessionId,
         cx: &mut App,
         f: impl 'static
-        + FnOnce(
-            Entity<Thread>,
-            &mut App,
-        ) -> Result<mpsc::UnboundedReceiver<Result<AgentResponseEvent>>>,
+        + FnOnce(Entity<Thread>, &mut App) -> Result<mpsc::UnboundedReceiver<Result<ThreadEvent>>>,
     ) -> Task<Result<acp::PromptResponse>> {
         let Some((thread, acp_thread)) = self.0.update(cx, |agent, _cx| {
             agent
@@ -476,10 +562,18 @@ impl NativeAgentConnection {
         };
         log::debug!("Found session for: {}", session_id);
 
-        let mut response_stream = match f(thread, cx) {
+        let response_stream = match f(thread, cx) {
             Ok(stream) => stream,
             Err(err) => return Task::ready(Err(err)),
         };
+        Self::handle_thread_events(response_stream, acp_thread, cx)
+    }
+
+    fn handle_thread_events(
+        mut response_stream: mpsc::UnboundedReceiver<Result<ThreadEvent>>,
+        acp_thread: WeakEntity<AcpThread>,
+        cx: &mut App,
+    ) -> Task<Result<acp::PromptResponse>> {
         cx.spawn(async move |cx| {
             // Handle response stream and forward to session.acp_thread
             while let Some(result) = response_stream.next().await {
@@ -488,7 +582,18 @@ impl NativeAgentConnection {
                         log::trace!("Received completion event: {:?}", event);
 
                         match event {
-                            AgentResponseEvent::Text(text) => {
+                            ThreadEvent::UserMessage(message) => {
+                                acp_thread.update(cx, |thread, cx| {
+                                    for content in message.content {
+                                        thread.push_user_content_block(
+                                            Some(message.id.clone()),
+                                            content.into(),
+                                            cx,
+                                        );
+                                    }
+                                })?;
+                            }
+                            ThreadEvent::AgentText(text) => {
                                 acp_thread.update(cx, |thread, cx| {
                                     thread.push_assistant_content_block(
                                         acp::ContentBlock::Text(acp::TextContent {
@@ -500,7 +605,7 @@ impl NativeAgentConnection {
                                     )
                                 })?;
                             }
-                            AgentResponseEvent::Thinking(text) => {
+                            ThreadEvent::AgentThinking(text) => {
                                 acp_thread.update(cx, |thread, cx| {
                                     thread.push_assistant_content_block(
                                         acp::ContentBlock::Text(acp::TextContent {
@@ -512,7 +617,7 @@ impl NativeAgentConnection {
                                     )
                                 })?;
                             }
-                            AgentResponseEvent::ToolCallAuthorization(ToolCallAuthorization {
+                            ThreadEvent::ToolCallAuthorization(ToolCallAuthorization {
                                 tool_call,
                                 options,
                                 response,
@@ -535,17 +640,21 @@ impl NativeAgentConnection {
                                 })
                                 .detach();
                             }
-                            AgentResponseEvent::ToolCall(tool_call) => {
+                            ThreadEvent::ToolCall(tool_call) => {
                                 acp_thread.update(cx, |thread, cx| {
                                     thread.upsert_tool_call(tool_call, cx)
                                 })??;
                             }
-                            AgentResponseEvent::ToolCallUpdate(update) => {
+                            ThreadEvent::ToolCallUpdate(update) => {
                                 acp_thread.update(cx, |thread, cx| {
                                     thread.update_tool_call(update, cx)
                                 })??;
                             }
-                            AgentResponseEvent::Stop(stop_reason) => {
+                            ThreadEvent::TitleUpdate(title) => {
+                                acp_thread
+                                    .update(cx, |thread, cx| thread.update_title(title, cx))??;
+                            }
+                            ThreadEvent::Stop(stop_reason) => {
                                 log::debug!("Assistant message complete: {:?}", stop_reason);
                                 return Ok(acp::PromptResponse { stop_reason });
                             }
@@ -564,6 +673,31 @@ impl NativeAgentConnection {
             })
         })
     }
+
+    fn register_tools(
+        thread: &mut Thread,
+        project: Entity<Project>,
+        action_log: Entity<action_log::ActionLog>,
+        cx: &mut Context<Thread>,
+    ) {
+        let language_registry = project.read(cx).languages().clone();
+        thread.add_tool(CopyPathTool::new(project.clone()));
+        thread.add_tool(CreateDirectoryTool::new(project.clone()));
+        thread.add_tool(DeletePathTool::new(project.clone(), action_log.clone()));
+        thread.add_tool(DiagnosticsTool::new(project.clone()));
+        thread.add_tool(EditFileTool::new(cx.weak_entity(), language_registry));
+        thread.add_tool(FetchTool::new(project.read(cx).client().http_client()));
+        thread.add_tool(FindPathTool::new(project.clone()));
+        thread.add_tool(GrepTool::new(project.clone()));
+        thread.add_tool(ListDirectoryTool::new(project.clone()));
+        thread.add_tool(MovePathTool::new(project.clone()));
+        thread.add_tool(NowTool);
+        thread.add_tool(OpenTool::new(project.clone()));
+        thread.add_tool(ReadFileTool::new(project.clone(), action_log));
+        thread.add_tool(TerminalTool::new(project.clone(), cx));
+        thread.add_tool(ThinkingTool);
+        thread.add_tool(WebSearchTool); // TODO: Enable this only if it's a zed model.
+    }
 }
 
 impl AgentModelSelector for NativeAgentConnection {
@@ -598,8 +732,8 @@ impl AgentModelSelector for NativeAgentConnection {
             return Task::ready(Err(anyhow!("Invalid model ID {}", model_id)));
         };
 
-        thread.update(cx, |thread, _cx| {
-            thread.set_model(model.clone());
+        thread.update(cx, |thread, cx| {
+            thread.set_model(model.clone(), cx);
         });
 
         update_settings_file::<AgentSettings>(
@@ -660,7 +794,7 @@ impl acp_thread::AgentConnection for NativeAgentConnection {
             log::debug!("Starting thread creation in async context");
 
             // Generate session ID
-            let session_id = acp::SessionId(uuid::Uuid::new_v4().to_string().into());
+            let session_id = generate_session_id();
             log::info!("Created session with ID: {}", session_id);
 
             // Create AcpThread
@@ -694,32 +828,21 @@ impl acp_thread::AgentConnection for NativeAgentConnection {
                             .model_from_id(&LanguageModels::model_id(&default_model.model))
                     });
 
+                    let summarization_model = registry.thread_summary_model().map(|c| c.model);
+
                     let thread = cx.new(|cx| {
                         let mut thread = Thread::new(
+                            session_id.clone(),
                             project.clone(),
                             agent.project_context.clone(),
                             agent.context_server_registry.clone(),
                             action_log.clone(),
                             agent.templates.clone(),
                             default_model,
+                            summarization_model,
                             cx,
                         );
-                        thread.add_tool(CopyPathTool::new(project.clone()));
-                        thread.add_tool(CreateDirectoryTool::new(project.clone()));
-                        thread.add_tool(DeletePathTool::new(project.clone(), action_log.clone()));
-                        thread.add_tool(DiagnosticsTool::new(project.clone()));
-                        thread.add_tool(EditFileTool::new(cx.entity()));
-                        thread.add_tool(FetchTool::new(project.read(cx).client().http_client()));
-                        thread.add_tool(FindPathTool::new(project.clone()));
-                        thread.add_tool(GrepTool::new(project.clone()));
-                        thread.add_tool(ListDirectoryTool::new(project.clone()));
-                        thread.add_tool(MovePathTool::new(project.clone()));
-                        thread.add_tool(NowTool);
-                        thread.add_tool(OpenTool::new(project.clone()));
-                        thread.add_tool(ReadFileTool::new(project.clone(), action_log));
-                        thread.add_tool(TerminalTool::new(project.clone(), cx));
-                        thread.add_tool(ThinkingTool);
-                        thread.add_tool(WebSearchTool); // TODO: Enable this only if it's a zed model.
+                        Self::register_tools(&mut thread, project, action_log, cx);
                         thread
                     });
 
@@ -729,16 +852,7 @@ impl acp_thread::AgentConnection for NativeAgentConnection {
 
             // Store the session
             agent.update(cx, |agent, cx| {
-                agent.sessions.insert(
-                    session_id,
-                    Session {
-                        thread,
-                        acp_thread: acp_thread.downgrade(),
-                        _subscription: cx.observe_release(&acp_thread, |this, acp_thread, _cx| {
-                            this.sessions.remove(acp_thread.session_id());
-                        }),
-                    },
-                );
+                agent.insert_session(thread, acp_thread.clone(), cx)
             })?;
 
             Ok(acp_thread)
@@ -797,7 +911,7 @@ impl acp_thread::AgentConnection for NativeAgentConnection {
         log::info!("Cancelling on session: {}", session_id);
         self.0.update(cx, |agent, cx| {
             if let Some(agent) = agent.sessions.get(session_id) {
-                agent.thread.update(cx, |thread, _cx| thread.cancel());
+                agent.thread.update(cx, |thread, cx| thread.cancel(cx));
             }
         });
     }
@@ -815,6 +929,10 @@ impl acp_thread::AgentConnection for NativeAgentConnection {
         })
     }
 
+    fn history(self: Rc<Self>) -> Option<Rc<dyn AgentHistory>> {
+        Some(self)
+    }
+
     fn into_any(self: Rc<Self>) -> Rc<dyn Any> {
         self
     }
@@ -824,7 +942,121 @@ struct NativeAgentSessionEditor(Entity<Thread>);
 
 impl acp_thread::AgentSessionEditor for NativeAgentSessionEditor {
     fn truncate(&self, message_id: acp_thread::UserMessageId, cx: &mut App) -> Task<Result<()>> {
-        Task::ready(self.0.update(cx, |thread, _cx| thread.truncate(message_id)))
+        Task::ready(
+            self.0
+                .update(cx, |thread, cx| thread.truncate(message_id, cx)),
+        )
+    }
+}
+
+impl acp_thread::AgentHistory for NativeAgentConnection {
+    fn list_threads(&self, cx: &mut App) -> Task<Result<Vec<AcpThreadMetadata>>> {
+        let database = self.0.read(cx).thread_database.clone();
+        cx.background_executor().spawn(async move {
+            let threads = database.list_threads().await?;
+            anyhow::Ok(
+                threads
+                    .into_iter()
+                    .map(|thread| thread.to_acp(NATIVE_AGENT_SERVER_NAME))
+                    .collect::<Vec<_>>(),
+            )
+        })
+    }
+
+    fn observe_history(&self, cx: &mut App) -> mpsc::UnboundedReceiver<AcpThreadMetadata> {
+        let (tx, rx) = mpsc::unbounded();
+        self.0.update(cx, |this, _| this.history_watchers.push(tx));
+        rx
+    }
+
+    fn load_thread(
+        self: Rc<Self>,
+        project: Entity<Project>,
+        _cwd: &Path,
+        session_id: acp::SessionId,
+        cx: &mut App,
+    ) -> Task<Result<Entity<acp_thread::AcpThread>>> {
+        let database = self.0.update(cx, |this, _| this.thread_database.clone());
+        cx.spawn(async move |cx| {
+            let db_thread = database
+                .load_thread(session_id.clone())
+                .await?
+                .context("no such thread found")?;
+
+            let acp_thread = cx.update(|cx| {
+                cx.new(|cx| {
+                    acp_thread::AcpThread::new(
+                        db_thread.title.clone(),
+                        self.clone(),
+                        project.clone(),
+                        session_id.clone(),
+                        cx,
+                    )
+                })
+            })?;
+            let action_log = cx.update(|cx| acp_thread.read(cx).action_log().clone())?;
+            let agent = self.0.clone();
+
+            // Create Thread
+            let thread = agent.update(cx, |agent, cx| {
+                let language_model_registry = LanguageModelRegistry::global(cx);
+                let configured_model = language_model_registry
+                    .update(cx, |registry, cx| {
+                        db_thread
+                            .model
+                            .as_ref()
+                            .and_then(|model| {
+                                let model = SelectedModel {
+                                    provider: model.provider.clone().into(),
+                                    model: model.model.clone().into(),
+                                };
+                                registry.select_model(&model, cx)
+                            })
+                            .or_else(|| registry.default_model())
+                    })
+                    .context("no default model configured")?;
+
+                let model = agent
+                    .models
+                    .model_from_id(&LanguageModels::model_id(&configured_model.model))
+                    .context("no model by id")?;
+
+                let summarization_model = language_model_registry
+                    .read(cx)
+                    .thread_summary_model()
+                    .map(|c| c.model);
+
+                let thread = cx.new(|cx| {
+                    let mut thread = Thread::from_db(
+                        session_id,
+                        db_thread,
+                        project.clone(),
+                        agent.project_context.clone(),
+                        agent.context_server_registry.clone(),
+                        action_log.clone(),
+                        agent.templates.clone(),
+                        model,
+                        summarization_model,
+                        cx,
+                    );
+                    Self::register_tools(&mut thread, project, action_log, cx);
+                    thread
+                });
+
+                anyhow::Ok(thread)
+            })??;
+
+            // Store the session
+            agent.update(cx, |agent, cx| {
+                agent.insert_session(thread.clone(), acp_thread.clone(), cx)
+            })?;
+
+            let events = thread.update(cx, |thread, cx| thread.replay(cx))?;
+            cx.update(|cx| Self::handle_thread_events(events, acp_thread.downgrade(), cx))?
+                .await?;
+
+            Ok(acp_thread)
+        })
     }
 }
 
@@ -844,12 +1076,16 @@ impl acp_thread::AgentSessionResume for NativeAgentSessionResume {
 
 #[cfg(test)]
 mod tests {
+    use crate::HistoryStore;
+
     use super::*;
     use acp_thread::{AgentConnection, AgentModelGroupName, AgentModelId, AgentModelInfo};
     use fs::FakeFs;
     use gpui::TestAppContext;
+    use language_model::fake_provider::FakeLanguageModel;
     use serde_json::json;
     use settings::SettingsStore;
+    use util::path;
 
     #[gpui::test]
     async fn test_maintaining_project_context(cx: &mut TestAppContext) {
@@ -1024,6 +1260,80 @@ mod tests {
         );
     }
 
+    #[gpui::test]
+    async fn test_history(cx: &mut TestAppContext) {
+        init_test(cx);
+        let fs = FakeFs::new(cx.executor());
+        let project = Project::test(fs.clone(), [], cx).await;
+
+        let agent = NativeAgent::new(
+            project.clone(),
+            Templates::new(),
+            None,
+            fs.clone(),
+            &mut cx.to_async(),
+        )
+        .await
+        .unwrap();
+        let connection = Rc::new(NativeAgentConnection(agent.clone()));
+        let history = connection.clone().history().unwrap();
+        let history_store = cx.new(|cx| HistoryStore::get_or_init(cx));
+
+        history_store
+            .update(cx, |history_store, cx| {
+                history_store.load_history(NATIVE_AGENT_SERVER_NAME.clone(), history.as_ref(), cx)
+            })
+            .await
+            .unwrap();
+
+        let acp_thread = cx
+            .update(|cx| {
+                connection
+                    .clone()
+                    .new_thread(project.clone(), Path::new(path!("")), cx)
+            })
+            .await
+            .unwrap();
+        let session_id = acp_thread.read_with(cx, |thread, _| thread.session_id().clone());
+        let selector = connection.model_selector().unwrap();
+
+        let summarization_model: Arc<dyn LanguageModel> =
+            Arc::new(FakeLanguageModel::default()) as _;
+
+        agent.update(cx, |agent, cx| {
+            let thread = agent.sessions.get(&session_id).unwrap().thread.clone();
+            thread.update(cx, |thread, cx| {
+                thread.set_summarization_model(Some(summarization_model.clone()), cx);
+            })
+        });
+
+        let model = cx
+            .update(|cx| selector.selected_model(&session_id, cx))
+            .await
+            .expect("selected_model should succeed");
+        let model = cx
+            .update(|cx| agent.read(cx).models().model_from_id(&model.id))
+            .unwrap();
+        let model = model.as_fake();
+
+        let send = acp_thread.update(cx, |thread, cx| thread.send_raw("Hi", cx));
+        let send = cx.foreground_executor().spawn(send);
+        cx.run_until_parked();
+        model.send_last_completion_stream_text_chunk("Hey");
+        model.end_last_completion_stream();
+        send.await.unwrap();
+
+        summarization_model
+            .as_fake()
+            .send_last_completion_stream_text_chunk("Saying Hello");
+        summarization_model.as_fake().end_last_completion_stream();
+        cx.executor().advance_clock(SAVE_THREAD_DEBOUNCE);
+
+        let history = history_store.update(cx, |store, cx| store.entries(cx));
+        assert_eq!(history.len(), 1);
+        assert_eq!(history[0].title(), "Saying Hello");
+    }
+
     fn init_test(cx: &mut TestAppContext) {
         env_logger::try_init().ok();
         cx.update(|cx| {

crates/agent2/src/agent2.rs

@@ -1,4 +1,6 @@
 mod agent;
+mod db;
+mod history_store;
 mod native_agent_server;
 mod templates;
 mod thread;
@@ -8,7 +10,15 @@ mod tools;
 mod tests;
 
 pub use agent::*;
+pub use db::*;
+pub use history_store::*;
 pub use native_agent_server::NativeAgentServer;
 pub use templates::*;
 pub use thread::*;
 pub use tools::*;
+
+use agent_client_protocol as acp;
+
+pub fn generate_session_id() -> acp::SessionId {
+    acp::SessionId(uuid::Uuid::new_v4().to_string().into())
+}

crates/agent2/src/db.rs

@@ -0,0 +1,488 @@
+use crate::{AgentMessage, AgentMessageContent, UserMessage, UserMessageContent};
+use acp_thread::{AcpThreadMetadata, AgentServerName};
+use agent::thread_store;
+use agent_client_protocol as acp;
+use agent_settings::{AgentProfileId, CompletionMode};
+use anyhow::{Result, anyhow};
+use chrono::{DateTime, Utc};
+use collections::{HashMap, IndexMap};
+use futures::{FutureExt, future::Shared};
+use gpui::{BackgroundExecutor, Global, Task};
+use indoc::indoc;
+use parking_lot::Mutex;
+use serde::{Deserialize, Serialize};
+use sqlez::{
+    bindable::{Bind, Column},
+    connection::Connection,
+    statement::Statement,
+};
+use std::sync::Arc;
+use ui::{App, SharedString};
+
+pub type DbMessage = crate::Message;
+pub type DbSummary = agent::thread::DetailedSummaryState;
+pub type DbLanguageModel = thread_store::SerializedLanguageModel;
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct DbThreadMetadata {
+    pub id: acp::SessionId,
+    #[serde(alias = "summary")]
+    pub title: SharedString,
+    pub updated_at: DateTime<Utc>,
+}
+
+impl DbThreadMetadata {
+    pub fn to_acp(self, agent: AgentServerName) -> AcpThreadMetadata {
+        AcpThreadMetadata {
+            agent,
+            id: self.id,
+            title: self.title,
+            updated_at: self.updated_at,
+        }
+    }
+}
+
+#[derive(Debug, Serialize, Deserialize)]
+pub struct DbThread {
+    pub title: SharedString,
+    pub messages: Vec<DbMessage>,
+    pub updated_at: DateTime<Utc>,
+    #[serde(default)]
+    pub summary: DbSummary,
+    #[serde(default)]
+    pub initial_project_snapshot: Option<Arc<agent::thread::ProjectSnapshot>>,
+    #[serde(default)]
+    pub cumulative_token_usage: language_model::TokenUsage,
+    #[serde(default)]
+    pub request_token_usage: Vec<language_model::TokenUsage>,
+    #[serde(default)]
+    pub model: Option<DbLanguageModel>,
+    #[serde(default)]
+    pub completion_mode: Option<CompletionMode>,
+    #[serde(default)]
+    pub profile: Option<AgentProfileId>,
+}
+
+impl DbThread {
+    pub const VERSION: &'static str = "0.3.0";
+
+    pub fn from_json(json: &[u8]) -> Result<Self> {
+        let saved_thread_json = serde_json::from_slice::<serde_json::Value>(json)?;
+        match saved_thread_json.get("version") {
+            Some(serde_json::Value::String(version)) => match version.as_str() {
+                Self::VERSION => Ok(serde_json::from_value(saved_thread_json)?),
+                _ => Self::upgrade_from_agent_1(agent::SerializedThread::from_json(json)?),
+            },
+            _ => Self::upgrade_from_agent_1(agent::SerializedThread::from_json(json)?),
+        }
+    }
+
+    fn upgrade_from_agent_1(thread: agent::SerializedThread) -> Result<Self> {
+        let mut messages = Vec::new();
+        for msg in thread.messages {
+            let message = match msg.role {
+                language_model::Role::User => {
+                    let mut content = Vec::new();
+
+                    // Convert segments to content
+                    for segment in msg.segments {
+                        match segment {
+                            thread_store::SerializedMessageSegment::Text { text } => {
+                                content.push(UserMessageContent::Text(text));
+                            }
+                            thread_store::SerializedMessageSegment::Thinking { text, .. } => {
+                                // User messages don't have thinking segments, but handle gracefully
+                                content.push(UserMessageContent::Text(text));
+                            }
+                            thread_store::SerializedMessageSegment::RedactedThinking { .. } => {
+                                // User messages don't have redacted thinking, skip.
+                            }
+                        }
+                    }
+
+                    // If no content was added, add context as text if available
+                    if content.is_empty() && !msg.context.is_empty() {
+                        content.push(UserMessageContent::Text(msg.context));
+                    }
+
+                    crate::Message::User(UserMessage {
+                        // MessageId from old format can't be meaningfully converted, so generate a new one
+                        id: acp_thread::UserMessageId::new(),
+                        content,
+                    })
+                }
+                language_model::Role::Assistant => {
+                    let mut content = Vec::new();
+
+                    // Convert segments to content
+                    for segment in msg.segments {
+                        match segment {
+                            thread_store::SerializedMessageSegment::Text { text } => {
+                                content.push(AgentMessageContent::Text(text));
+                            }
+                            thread_store::SerializedMessageSegment::Thinking {
+                                text,
+                                signature,
+                            } => {
+                                content.push(AgentMessageContent::Thinking { text, signature });
+                            }
+                            thread_store::SerializedMessageSegment::RedactedThinking { data } => {
+                                content.push(AgentMessageContent::RedactedThinking(data));
+                            }
+                        }
+                    }
+
+                    // Convert tool uses
+                    let mut tool_names_by_id = HashMap::default();
+                    for tool_use in msg.tool_uses {
+                        tool_names_by_id.insert(tool_use.id.clone(), tool_use.name.clone());
+                        content.push(AgentMessageContent::ToolUse(
+                            language_model::LanguageModelToolUse {
+                                id: tool_use.id,
+                                name: tool_use.name.into(),
+                                raw_input: serde_json::to_string(&tool_use.input)
+                                    .unwrap_or_default(),
+                                input: tool_use.input,
+                                is_input_complete: true,
+                            },
+                        ));
+                    }
+
+                    // Convert tool results
+                    let mut tool_results = IndexMap::default();
+                    for tool_result in msg.tool_results {
+                        let name = tool_names_by_id
+                            .remove(&tool_result.tool_use_id)
+                            .unwrap_or_else(|| SharedString::from("unknown"));
+                        tool_results.insert(
+                            tool_result.tool_use_id.clone(),
+                            language_model::LanguageModelToolResult {
+                                tool_use_id: tool_result.tool_use_id,
+                                tool_name: name.into(),
+                                is_error: tool_result.is_error,
+                                content: tool_result.content,
+                                output: tool_result.output,
+                            },
+                        );
+                    }
+
+                    crate::Message::Agent(AgentMessage {
+                        content,
+                        tool_results,
+                    })
+                }
+                language_model::Role::System => {
+                    // Skip system messages as they're not supported in the new format
+                    continue;
+                }
+            };
+
+            messages.push(message);
+        }
+
+        Ok(Self {
+            title: thread.summary,
+            messages,
+            updated_at: thread.updated_at,
+            summary: thread.detailed_summary_state,
+            initial_project_snapshot: thread.initial_project_snapshot,
+            cumulative_token_usage: thread.cumulative_token_usage,
+            request_token_usage: thread.request_token_usage,
+            model: thread.model,
+            completion_mode: thread.completion_mode,
+            profile: thread.profile,
+        })
+    }
+}
+
+pub static ZED_STATELESS: std::sync::LazyLock<bool> =
+    std::sync::LazyLock::new(|| std::env::var("ZED_STATELESS").map_or(false, |v| !v.is_empty()));
+
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+pub enum DataType {
+    #[serde(rename = "json")]
+    Json,
+    #[serde(rename = "zstd")]
+    Zstd,
+}
+
+impl Bind for DataType {
+    fn bind(&self, statement: &Statement, start_index: i32) -> Result<i32> {
+        let value = match self {
+            DataType::Json => "json",
+            DataType::Zstd => "zstd",
+        };
+        value.bind(statement, start_index)
+    }
+}
+
+impl Column for DataType {
+    fn column(statement: &mut Statement, start_index: i32) -> Result<(Self, i32)> {
+        let (value, next_index) = String::column(statement, start_index)?;
+        let data_type = match value.as_str() {
+            "json" => DataType::Json,
+            "zstd" => DataType::Zstd,
+            _ => anyhow::bail!("Unknown data type: {}", value),
+        };
+        Ok((data_type, next_index))
+    }
+}
+
+pub(crate) struct ThreadsDatabase {
+    executor: BackgroundExecutor,
+    connection: Arc<Mutex<Connection>>,
+}
+
+struct GlobalThreadsDatabase(Shared<Task<Result<Arc<ThreadsDatabase>, Arc<anyhow::Error>>>>);
+
+impl Global for GlobalThreadsDatabase {}
+
+impl ThreadsDatabase {
+    fn connection(&self) -> Arc<Mutex<Connection>> {
+        self.connection.clone()
+    }
+
+    const COMPRESSION_LEVEL: i32 = 3;
+}
+
+impl ThreadsDatabase {
+    pub fn connect(cx: &mut App) -> Shared<Task<Result<Arc<ThreadsDatabase>, Arc<anyhow::Error>>>> {
+        if cx.has_global::<GlobalThreadsDatabase>() {
+            return cx.global::<GlobalThreadsDatabase>().0.clone();
+        }
+        let executor = cx.background_executor().clone();
+        let task = executor
+            .spawn({
+                let executor = executor.clone();
+                async move {
+                    match ThreadsDatabase::new(executor) {
+                        Ok(db) => Ok(Arc::new(db)),
+                        Err(err) => Err(Arc::new(err)),
+                    }
+                }
+            })
+            .shared();
+
+        cx.set_global(GlobalThreadsDatabase(task.clone()));
+        task
+    }
+
+    pub fn new(executor: BackgroundExecutor) -> Result<Self> {
+        let connection = if *ZED_STATELESS || cfg!(any(feature = "test-support", test)) {
+            Connection::open_memory(Some("THREAD_FALLBACK_DB"))
+        } else {
+            let threads_dir = paths::data_dir().join("threads");
+            std::fs::create_dir_all(&threads_dir)?;
+            let sqlite_path = threads_dir.join("threads.db");
+            Connection::open_file(&sqlite_path.to_string_lossy())
+        };
+
+        connection.exec(indoc! {"
+            CREATE TABLE IF NOT EXISTS threads (
+                id TEXT PRIMARY KEY,
+                summary TEXT NOT NULL,
+                updated_at TEXT NOT NULL,
+                data_type TEXT NOT NULL,
+                data BLOB NOT NULL
+            )
+        "})?()
+        .map_err(|e| anyhow!("Failed to create threads table: {}", e))?;
+
+        let db = Self {
+            executor: executor.clone(),
+            connection: Arc::new(Mutex::new(connection)),
+        };
+
+        Ok(db)
+    }
+
+    fn save_thread_sync(
+        connection: &Arc<Mutex<Connection>>,
+        id: acp::SessionId,
+        thread: DbThread,
+    ) -> Result<DbThreadMetadata> {
+        let json_data = serde_json::to_string(&thread)?;
+        let title = thread.title.to_string();
+        let updated_at = thread.updated_at.to_rfc3339();
+
+        let connection = connection.lock();
+
+        let compressed = zstd::encode_all(json_data.as_bytes(), Self::COMPRESSION_LEVEL)?;
+        let data_type = DataType::Zstd;
+        let data = compressed;
+
+        let mut insert = connection.exec_bound::<(Arc<str>, String, String, DataType, Vec<u8>)>(indoc! {"
+            INSERT OR REPLACE INTO threads (id, summary, updated_at, data_type, data) VALUES (?, ?, ?, ?, ?)
+        "})?;
+
+        insert((id.0.clone(), title, updated_at, data_type, data))?;
+
+        Ok(DbThreadMetadata {
+            id,
+            title: thread.title,
+            updated_at: thread.updated_at,
+        })
+    }
+
+    pub fn list_threads(&self) -> Task<Result<Vec<DbThreadMetadata>>> {
+        let connection = self.connection.clone();
+
+        self.executor.spawn(async move {
+            let connection = connection.lock();
+            let mut select =
+                connection.select_bound::<(), (Arc<str>, String, String)>(indoc! {"
+                SELECT id, summary, updated_at FROM threads ORDER BY updated_at DESC
+            "})?;
+
+            let rows = select(())?;
+            let mut threads = Vec::new();
+
+            for (id, summary, updated_at) in rows {
+                threads.push(DbThreadMetadata {
+                    id: acp::SessionId(id),
+                    title: summary.into(),
+                    updated_at: DateTime::parse_from_rfc3339(&updated_at)?.with_timezone(&Utc),
+                });
+            }
+
+            Ok(threads)
+        })
+    }
+
+    pub fn load_thread(&self, id: acp::SessionId) -> Task<Result<Option<DbThread>>> {
+        let connection = self.connection.clone();
+
+        self.executor.spawn(async move {
+            let connection = connection.lock();
+            let mut select = connection.select_bound::<Arc<str>, (DataType, Vec<u8>)>(indoc! {"
+                SELECT data_type, data FROM threads WHERE id = ? LIMIT 1
+            "})?;
+
+            let rows = select(id.0)?;
+            if let Some((data_type, data)) = rows.into_iter().next() {
+                let json_data = match data_type {
+                    DataType::Zstd => {
+                        let decompressed = zstd::decode_all(&data[..])?;
+                        String::from_utf8(decompressed)?
+                    }
+                    DataType::Json => String::from_utf8(data)?,
+                };
+                dbg!(&json_data);
+
+                let thread = dbg!(DbThread::from_json(json_data.as_bytes()))?;
+                Ok(Some(thread))
+            } else {
+                Ok(None)
+            }
+        })
+    }
+
+    pub fn save_thread(
+        &self,
+        id: acp::SessionId,
+        thread: DbThread,
+    ) -> Task<Result<DbThreadMetadata>> {
+        let connection = self.connection.clone();
+
+        self.executor
+            .spawn(async move { Self::save_thread_sync(&connection, id, thread) })
+    }
+
+    pub fn delete_thread(&self, id: acp::SessionId) -> Task<Result<()>> {
+        let connection = self.connection.clone();
+
+        self.executor.spawn(async move {
+            let connection = connection.lock();
+
+            let mut delete = connection.exec_bound::<Arc<str>>(indoc! {"
+                DELETE FROM threads WHERE id = ?
+            "})?;
+
+            delete(id.0)?;
+
+            Ok(())
+        })
+    }
+}
+
+#[cfg(test)]
+mod tests {
+
+    use super::*;
+    use agent::MessageSegment;
+    use agent::context::LoadedContext;
+    use client::Client;
+    use fs::FakeFs;
+    use gpui::AppContext;
+    use gpui::TestAppContext;
+    use http_client::FakeHttpClient;
+    use language_model::Role;
+    use project::Project;
+    use settings::SettingsStore;
+
+    fn init_test(cx: &mut TestAppContext) {
+        env_logger::try_init().ok();
+        cx.update(|cx| {
+            let settings_store = SettingsStore::test(cx);
+            cx.set_global(settings_store);
+            Project::init_settings(cx);
+            language::init(cx);
+
+            let http_client = FakeHttpClient::with_404_response();
+            let clock = Arc::new(clock::FakeSystemClock::new());
+            let client = Client::new(clock, http_client, cx);
+            agent::init(cx);
+            agent_settings::init(cx);
+            language_model::init(client.clone(), cx);
+        });
+    }
+
+    #[gpui::test]
+    async fn test_retrieving_old_thread(cx: &mut TestAppContext) {
+        init_test(cx);
+        let fs = FakeFs::new(cx.executor());
+        let project = Project::test(fs, [], cx).await;
+
+        // Save a thread using the old agent.
+        {
+            let thread_store = cx.new(|cx| agent::ThreadStore::fake(project, cx));
+            let thread = thread_store.update(cx, |thread_store, cx| thread_store.create_thread(cx));
+            thread.update(cx, |thread, cx| {
+                thread.insert_message(
+                    Role::User,
+                    vec![MessageSegment::Text("Hey!".into())],
+                    LoadedContext::default(),
+                    vec![],
+                    false,
+                    cx,
+                );
+                thread.insert_message(
+                    Role::Assistant,
+                    vec![MessageSegment::Text("How're you doing?".into())],
+                    LoadedContext::default(),
+                    vec![],
+                    false,
+                    cx,
+                )
+            });
+            thread_store
+                .update(cx, |thread_store, cx| thread_store.save_thread(&thread, cx))
+                .await
+                .unwrap();
+        }
+
+        let db = cx.update(|cx| ThreadsDatabase::connect(cx)).await.unwrap();
+        let threads = db.list_threads().await.unwrap();
+        assert_eq!(threads.len(), 1);
+        let thread = db
+            .load_thread(threads[0].id.clone())
+            .await
+            .unwrap()
+            .unwrap();
+        assert_eq!(thread.messages[0].to_markdown(), "## User\n\nHey!\n");
+        assert_eq!(
+            thread.messages[1].to_markdown(),
+            "## Assistant\n\nHow're you doing?\n"
+        );
+    }
+}

crates/agent2/src/history_store.rs

@@ -0,0 +1,174 @@
+use acp_thread::{AcpThreadMetadata, AgentConnection, AgentServerName};
+use agent_client_protocol as acp;
+use agent_servers::AgentServer;
+use assistant_context::SavedContextMetadata;
+use chrono::{DateTime, Utc};
+use collections::HashMap;
+use gpui::{Entity, Global, SharedString, Task, prelude::*};
+use project::Project;
+use serde::{Deserialize, Serialize};
+use ui::App;
+
+use std::{path::Path, rc::Rc, sync::Arc, time::Duration};
+
+use crate::NativeAgentServer;
+
+const MAX_RECENTLY_OPENED_ENTRIES: usize = 6;
+const NAVIGATION_HISTORY_PATH: &str = "agent-navigation-history.json";
+const SAVE_RECENTLY_OPENED_ENTRIES_DEBOUNCE: Duration = Duration::from_millis(50);
+
+// todo!(put this in the UI)
+#[derive(Clone, Debug)]
+pub enum HistoryEntry {
+    AcpThread(AcpThreadMetadata),
+    TextThread(SavedContextMetadata),
+}
+
+impl HistoryEntry {
+    pub fn updated_at(&self) -> DateTime<Utc> {
+        match self {
+            HistoryEntry::AcpThread(thread) => thread.updated_at,
+            HistoryEntry::TextThread(context) => context.mtime.to_utc(),
+        }
+    }
+
+    pub fn id(&self) -> HistoryEntryId {
+        match self {
+            HistoryEntry::AcpThread(thread) => {
+                HistoryEntryId::Thread(thread.agent.clone(), thread.id.clone())
+            }
+            HistoryEntry::TextThread(context) => HistoryEntryId::Context(context.path.clone()),
+        }
+    }
+
+    pub fn title(&self) -> &SharedString {
+        match self {
+            HistoryEntry::AcpThread(thread) => &thread.title,
+            HistoryEntry::TextThread(context) => &context.title,
+        }
+    }
+}
+
+/// Generic identifier for a history entry.
+#[derive(Clone, PartialEq, Eq, Debug)]
+pub enum HistoryEntryId {
+    Thread(AgentServerName, acp::SessionId),
+    Context(Arc<Path>),
+}
+
+#[derive(Serialize, Deserialize)]
+enum SerializedRecentOpen {
+    Thread(String),
+    ContextName(String),
+    /// Old format which stores the full path
+    Context(String),
+}
+
+#[derive(Default)]
+pub struct AgentHistory {
+    entries: HashMap<acp::SessionId, AcpThreadMetadata>,
+    loaded: bool,
+}
+
+pub struct HistoryStore {
+    agents: HashMap<AgentServerName, AgentHistory>, // todo!() text threads
+}
+// note, we have to share the history store between all windows
+// because we only get updates from one connection at a time.
+struct GlobalHistoryStore(Entity<HistoryStore>);
+impl Global for GlobalHistoryStore {}
+
+impl HistoryStore {
+    pub fn get_or_init(project: &Entity<Project>, cx: &mut App) -> Entity<Self> {
+        if cx.has_global::<GlobalHistoryStore>() {
+            return cx.global::<GlobalHistoryStore>().0.clone();
+        }
+        let history_store = cx.new(|cx| HistoryStore::new(cx));
+        cx.set_global(GlobalHistoryStore(history_store.clone()));
+        let root_dir = project
+            .read(cx)
+            .visible_worktrees(cx)
+            .next()
+            .map(|worktree| worktree.read(cx).abs_path())
+            .unwrap_or_else(|| paths::home_dir().as_path().into());
+
+        let agent = NativeAgentServer::new(project.read(cx).fs().clone());
+        let connect = agent.connect(&root_dir, project, cx);
+        cx.spawn({
+            let history_store = history_store.clone();
+            async move |cx| {
+                let connection = connect.await?.history().unwrap();
+                history_store
+                    .update(cx, |history_store, cx| {
+                        history_store.load_history(agent.name(), connection.as_ref(), cx)
+                    })?
+                    .await
+            }
+        })
+        .detach_and_log_err(cx);
+        history_store
+    }
+
+    fn new(_cx: &mut Context<Self>) -> Self {
+        Self {
+            agents: HashMap::default(),
+        }
+    }
+
+    pub fn update_history(&mut self, entry: AcpThreadMetadata, cx: &mut Context<Self>) {
+        let agent = self
+            .agents
+            .entry(entry.agent.clone())
+            .or_insert(Default::default());
+
+        agent.entries.insert(entry.id.clone(), entry);
+        cx.notify()
+    }
+
+    pub fn load_history(
+        &mut self,
+        agent_name: AgentServerName,
+        connection: &dyn acp_thread::AgentHistory,
+        cx: &mut Context<Self>,
+    ) -> Task<anyhow::Result<()>> {
+        let threads = connection.list_threads(cx);
+        cx.spawn(async move |this, cx| {
+            let threads = threads.await?;
+
+            this.update(cx, |this, cx| {
+                this.agents.insert(
+                    agent_name,
+                    AgentHistory {
+                        loaded: true,
+                        entries: threads.into_iter().map(|t| (t.id.clone(), t)).collect(),
+                    },
+                );
+                cx.notify()
+            })
+        })
+    }
+
+    pub fn entries(&mut self, _cx: &mut Context<Self>) -> Vec<HistoryEntry> {
+        let mut history_entries = Vec::new();
+
+        #[cfg(debug_assertions)]
+        if std::env::var("ZED_SIMULATE_NO_THREAD_HISTORY").is_ok() {
+            return history_entries;
+        }
+
+        history_entries.extend(
+            self.agents
+                .values_mut()
+                .flat_map(|history| history.entries.values().cloned()) // todo!("surface the loading state?")
+                .map(HistoryEntry::AcpThread),
+        );
+        // todo!() include the text threads in here.
+
+        history_entries.sort_unstable_by_key(|entry| std::cmp::Reverse(entry.updated_at()));
+        history_entries
+    }
+
+    pub fn recent_entries(&mut self, limit: usize, cx: &mut Context<Self>) -> Vec<HistoryEntry> {
+        self.entries(cx).into_iter().take(limit).collect()
+    }
+}

crates/agent2/src/native_agent_server.rs

@@ -1,11 +1,13 @@
 use std::{path::Path, rc::Rc, sync::Arc};
 
+use acp_thread::AgentServerName;
 use agent_servers::AgentServer;
 use anyhow::Result;
 use fs::Fs;
 use gpui::{App, Entity, Task};
 use project::Project;
 use prompt_store::PromptStore;
+use ui::SharedString;
 
 use crate::{NativeAgent, NativeAgentConnection, templates::Templates};
 
@@ -20,9 +22,12 @@ impl NativeAgentServer {
     }
 }
 
+pub const NATIVE_AGENT_SERVER_NAME: AgentServerName =
+    AgentServerName(SharedString::new_static("Native Agent"));
+
 impl AgentServer for NativeAgentServer {
-    fn name(&self) -> &'static str {
-        "Native Agent"
+    fn name(&self) -> AgentServerName {
+        NATIVE_AGENT_SERVER_NAME.clone()
     }
 
     fn empty_state_headline(&self) -> &'static str {

crates/agent2/src/tests/mod.rs

@@ -343,7 +343,7 @@ async fn test_streaming_tool_calls(cx: &mut TestAppContext) {
 
     let mut saw_partial_tool_use = false;
     while let Some(event) = events.next().await {
-        if let Ok(AgentResponseEvent::ToolCall(tool_call)) = event {
+        if let Ok(ThreadEvent::ToolCall(tool_call)) = event {
             thread.update(cx, |thread, _cx| {
                 // Look for a tool use in the thread's last message
                 let message = thread.last_message().unwrap();
@@ -733,16 +733,14 @@ async fn test_send_after_tool_use_limit(cx: &mut TestAppContext) {
     );
 }
 
-async fn expect_tool_call(
-    events: &mut UnboundedReceiver<Result<AgentResponseEvent>>,
-) -> acp::ToolCall {
+async fn expect_tool_call(events: &mut UnboundedReceiver<Result<ThreadEvent>>) -> acp::ToolCall {
     let event = events
         .next()
         .await
         .expect("no tool call authorization event received")
         .unwrap();
     match event {
-        AgentResponseEvent::ToolCall(tool_call) => return tool_call,
+        ThreadEvent::ToolCall(tool_call) => return tool_call,
         event => {
             panic!("Unexpected event {event:?}");
         }
@@ -750,7 +748,7 @@ async fn expect_tool_call(
 }
 
 async fn expect_tool_call_update_fields(
-    events: &mut UnboundedReceiver<Result<AgentResponseEvent>>,
+    events: &mut UnboundedReceiver<Result<ThreadEvent>>,
 ) -> acp::ToolCallUpdate {
     let event = events
         .next()
@@ -758,7 +756,7 @@ async fn expect_tool_call_update_fields(
         .expect("no tool call authorization event received")
         .unwrap();
     match event {
-        AgentResponseEvent::ToolCallUpdate(acp_thread::ToolCallUpdate::UpdateFields(update)) => {
+        ThreadEvent::ToolCallUpdate(acp_thread::ToolCallUpdate::UpdateFields(update)) => {
             return update;
         }
         event => {
@@ -768,7 +766,7 @@ async fn expect_tool_call_update_fields(
 }
 
 async fn next_tool_call_authorization(
-    events: &mut UnboundedReceiver<Result<AgentResponseEvent>>,
+    events: &mut UnboundedReceiver<Result<ThreadEvent>>,
 ) -> ToolCallAuthorization {
     loop {
         let event = events
@@ -776,7 +774,7 @@ async fn next_tool_call_authorization(
             .await
             .expect("no tool call authorization event received")
             .unwrap();
-        if let AgentResponseEvent::ToolCallAuthorization(tool_call_authorization) = event {
+        if let ThreadEvent::ToolCallAuthorization(tool_call_authorization) = event {
             let permission_kinds = tool_call_authorization
                 .options
                 .iter()
@@ -943,13 +941,13 @@ async fn test_cancellation(cx: &mut TestAppContext) {
     let mut echo_completed = false;
     while let Some(event) = events.next().await {
         match event.unwrap() {
-            AgentResponseEvent::ToolCall(tool_call) => {
+            ThreadEvent::ToolCall(tool_call) => {
                 assert_eq!(tool_call.title, expected_tools.remove(0));
                 if tool_call.title == "Echo" {
                     echo_id = Some(tool_call.id);
                 }
             }
-            AgentResponseEvent::ToolCallUpdate(acp_thread::ToolCallUpdate::UpdateFields(
+            ThreadEvent::ToolCallUpdate(acp_thread::ToolCallUpdate::UpdateFields(
                 acp::ToolCallUpdate {
                     id,
                     fields:
@@ -971,13 +969,13 @@ async fn test_cancellation(cx: &mut TestAppContext) {
 
     // Cancel the current send and ensure that the event stream is closed, even
     // if one of the tools is still running.
-    thread.update(cx, |thread, _cx| thread.cancel());
+    thread.update(cx, |thread, cx| thread.cancel(cx));
     let events = events.collect::<Vec<_>>().await;
     let last_event = events.last();
     assert!(
         matches!(
             last_event,
-            Some(Ok(AgentResponseEvent::Stop(acp::StopReason::Canceled)))
+            Some(Ok(ThreadEvent::Stop(acp::StopReason::Canceled)))
         ),
         "unexpected event {last_event:?}"
     );
@@ -1159,7 +1157,7 @@ async fn test_truncate(cx: &mut TestAppContext) {
     });
 
     thread
-        .update(cx, |thread, _cx| thread.truncate(message_id))
+        .update(cx, |thread, cx| thread.truncate(message_id, cx))
         .unwrap();
     cx.run_until_parked();
     thread.read_with(cx, |thread, _| {
@@ -1434,11 +1432,11 @@ async fn test_tool_updates_to_completion(cx: &mut TestAppContext) {
 }
 
 /// Filters out the stop events for asserting against in tests
-fn stop_events(result_events: Vec<Result<AgentResponseEvent>>) -> Vec<acp::StopReason> {
+fn stop_events(result_events: Vec<Result<ThreadEvent>>) -> Vec<acp::StopReason> {
     result_events
         .into_iter()
         .filter_map(|event| match event.unwrap() {
-            AgentResponseEvent::Stop(stop_reason) => Some(stop_reason),
+            ThreadEvent::Stop(stop_reason) => Some(stop_reason),
             _ => None,
         })
         .collect()
@@ -1549,12 +1547,14 @@ async fn setup(cx: &mut TestAppContext, model: TestModel) -> ThreadTest {
     let action_log = cx.new(|_| ActionLog::new(project.clone()));
     let thread = cx.new(|cx| {
         Thread::new(
+            generate_session_id(),
             project,
             project_context.clone(),
             context_server_registry,
             action_log,
             templates,
             Some(model.clone()),
+            None,
             cx,
         )
     });

crates/agent2/src/tools/context_server_registry.rs

@@ -228,4 +228,14 @@ impl AnyAgentTool for ContextServerTool {
             })
         })
     }
+
+    fn replay(
+        &self,
+        _input: serde_json::Value,
+        _output: serde_json::Value,
+        _event_stream: ToolCallEventStream,
+        _cx: &mut App,
+    ) -> Result<()> {
+        Ok(())
+    }
 }

crates/agent2/src/tools/edit_file_tool.rs

@@ -5,10 +5,10 @@ use anyhow::{Context as _, Result, anyhow};
 use assistant_tools::edit_agent::{EditAgent, EditAgentOutput, EditAgentOutputEvent, EditFormat};
 use cloud_llm_client::CompletionIntent;
 use collections::HashSet;
-use gpui::{App, AppContext, AsyncApp, Entity, Task};
+use gpui::{App, AppContext, AsyncApp, Entity, Task, WeakEntity};
 use indoc::formatdoc;
-use language::ToPoint;
 use language::language_settings::{self, FormatOnSave};
+use language::{LanguageRegistry, ToPoint};
 use language_model::LanguageModelToolResultContent;
 use paths;
 use project::lsp_store::{FormatTrigger, LspFormatTarget};
@@ -98,11 +98,13 @@ pub enum EditFileMode {
 
 #[derive(Debug, Serialize, Deserialize)]
 pub struct EditFileToolOutput {
+    #[serde(alias = "original_path")]
     input_path: PathBuf,
-    project_path: PathBuf,
     new_text: String,
     old_text: Arc<String>,
+    #[serde(default)]
     diff: String,
+    #[serde(alias = "raw_output")]
     edit_agent_output: EditAgentOutput,
 }
 
@@ -122,12 +124,16 @@ impl From<EditFileToolOutput> for LanguageModelToolResultContent {
 }
 
 pub struct EditFileTool {
-    thread: Entity<Thread>,
+    thread: WeakEntity<Thread>,
+    language_registry: Arc<LanguageRegistry>,
 }
 
 impl EditFileTool {
-    pub fn new(thread: Entity<Thread>) -> Self {
-        Self { thread }
+    pub fn new(thread: WeakEntity<Thread>, language_registry: Arc<LanguageRegistry>) -> Self {
+        Self {
+            thread,
+            language_registry,
+        }
     }
 
     fn authorize(
@@ -167,8 +173,11 @@ impl EditFileTool {
 
         // Check if path is inside the global config directory
         // First check if it's already inside project - if not, try to canonicalize
-        let thread = self.thread.read(cx);
-        let project_path = thread.project().read(cx).find_project_path(&input.path, cx);
+        let Ok(project_path) = self.thread.read_with(cx, |thread, cx| {
+            thread.project().read(cx).find_project_path(&input.path, cx)
+        }) else {
+            return Task::ready(Err(anyhow!("thread was dropped")));
+        };
 
         // If the path is inside the project, and it's not one of the above edge cases,
         // then no confirmation is necessary. Otherwise, confirmation is necessary.
@@ -221,7 +230,12 @@ impl AgentTool for EditFileTool {
         event_stream: ToolCallEventStream,
         cx: &mut App,
     ) -> Task<Result<Self::Output>> {
-        let project = self.thread.read(cx).project().clone();
+        let Ok(project) = self
+            .thread
+            .read_with(cx, |thread, _cx| thread.project().clone())
+        else {
+            return Task::ready(Err(anyhow!("thread was dropped")));
+        };
         let project_path = match resolve_path(&input, project.clone(), cx) {
             Ok(path) => path,
             Err(err) => return Task::ready(Err(anyhow!(err))),
@@ -237,23 +251,17 @@ impl AgentTool for EditFileTool {
             });
         }
 
-        let Some(request) = self.thread.update(cx, |thread, cx| {
-            thread
-                .build_completion_request(CompletionIntent::ToolResults, cx)
-                .ok()
-        }) else {
-            return Task::ready(Err(anyhow!("Failed to build completion request")));
-        };
-        let thread = self.thread.read(cx);
-        let Some(model) = thread.model().cloned() else {
-            return Task::ready(Err(anyhow!("No language model configured")));
-        };
-        let action_log = thread.action_log().clone();
-
         let authorize = self.authorize(&input, &event_stream, cx);
         cx.spawn(async move |cx: &mut AsyncApp| {
             authorize.await?;
 
+            let (request, model, action_log) = self.thread.update(cx, |thread, cx| {
+                let request = thread.build_completion_request(CompletionIntent::ToolResults, cx);
+                (request, thread.model().cloned(), thread.action_log().clone())
+            })?;
+            let request = request?;
+            let model = model.context("No language model configured")?;
+
             let edit_format = EditFormat::from_model(model.clone())?;
             let edit_agent = EditAgent::new(
                 model,
@@ -419,7 +427,6 @@ impl AgentTool for EditFileTool {
 
             Ok(EditFileToolOutput {
                 input_path: input.path,
-                project_path: project_path.path.to_path_buf(),
                 new_text: new_text.clone(),
                 old_text,
                 diff: unified_diff,
@@ -427,6 +434,25 @@ impl AgentTool for EditFileTool {
             })
         })
     }
+
+    fn replay(
+        &self,
+        _input: Self::Input,
+        output: Self::Output,
+        event_stream: ToolCallEventStream,
+        cx: &mut App,
+    ) -> Result<()> {
+        event_stream.update_diff(cx.new(|cx| {
+            Diff::finalized(
+                output.input_path,
+                Some(output.old_text.to_string()),
+                output.new_text,
+                self.language_registry.clone(),
+                cx,
+            )
+        }));
+        Ok(())
+    }
 }
 
 /// Validate that the file path is valid, meaning:
@@ -497,7 +523,6 @@ fn resolve_path(
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::{ContextServerRegistry, Templates};
     use action_log::ActionLog;
     use client::TelemetrySettings;
     use fs::Fs;
@@ -505,7 +530,6 @@ mod tests {
     use language_model::fake_provider::FakeLanguageModel;
     use serde_json::json;
     use settings::SettingsStore;
-    use std::rc::Rc;
     use util::path;
 
     #[gpui::test]
@@ -515,21 +539,10 @@ mod tests {
         let fs = project::FakeFs::new(cx.executor());
         fs.insert_tree("/root", json!({})).await;
         let project = Project::test(fs.clone(), [path!("/root").as_ref()], cx).await;
+        let language_registry = project.read_with(cx, |project, _cx| project.languages().clone());
         let action_log = cx.new(|_| ActionLog::new(project.clone()));
-        let context_server_registry =
-            cx.new(|cx| ContextServerRegistry::new(project.read(cx).context_server_store(), cx));
         let model = Arc::new(FakeLanguageModel::default());
-        let thread = cx.new(|cx| {
-            Thread::new(
-                project,
-                Rc::default(),
-                context_server_registry,
-                action_log,
-                Templates::new(),
-                Some(model),
-                cx,
-            )
-        });
+        let thread = cx.new(|cx| Thread::test(model, project, action_log, cx));
         let result = cx
             .update(|cx| {
                 let input = EditFileToolInput {
@@ -537,7 +550,11 @@ mod tests {
                     path: "root/nonexistent_file.txt".into(),
                     mode: EditFileMode::Edit,
                 };
-                Arc::new(EditFileTool { thread }).run(input, ToolCallEventStream::test().0, cx)
+                Arc::new(EditFileTool::new(thread.downgrade(), language_registry)).run(
+                    input,
+                    ToolCallEventStream::test().0,
+                    cx,
+                )
             })
             .await;
         assert_eq!(
@@ -713,20 +730,8 @@ mod tests {
         });
 
         let action_log = cx.new(|_| ActionLog::new(project.clone()));
-        let context_server_registry =
-            cx.new(|cx| ContextServerRegistry::new(project.read(cx).context_server_store(), cx));
         let model = Arc::new(FakeLanguageModel::default());
-        let thread = cx.new(|cx| {
-            Thread::new(
-                project,
-                Rc::default(),
-                context_server_registry,
-                action_log.clone(),
-                Templates::new(),
-                Some(model.clone()),
-                cx,
-            )
-        });
+        let thread = cx.new(|cx| Thread::test(model.clone(), project, action_log.clone(), cx));
 
         // First, test with format_on_save enabled
         cx.update(|cx| {
@@ -750,9 +755,10 @@ mod tests {
                     path: "root/src/main.rs".into(),
                     mode: EditFileMode::Overwrite,
                 };
-                Arc::new(EditFileTool {
-                    thread: thread.clone(),
-                })
+                Arc::new(EditFileTool::new(
+                    thread.downgrade(),
+                    language_registry.clone(),
+                ))
                 .run(input, ToolCallEventStream::test().0, cx)
             });
 
@@ -806,7 +812,11 @@ mod tests {
                     path: "root/src/main.rs".into(),
                     mode: EditFileMode::Overwrite,
                 };
-                Arc::new(EditFileTool { thread }).run(input, ToolCallEventStream::test().0, cx)
+                Arc::new(EditFileTool::new(thread.downgrade(), language_registry)).run(
+                    input,
+                    ToolCallEventStream::test().0,
+                    cx,
+                )
             });
 
             // Stream the unformatted content
@@ -848,21 +858,10 @@ mod tests {
         .unwrap();
 
         let project = Project::test(fs.clone(), [path!("/root").as_ref()], cx).await;
-        let context_server_registry =
-            cx.new(|cx| ContextServerRegistry::new(project.read(cx).context_server_store(), cx));
+        let language_registry = project.read_with(cx, |project, _cx| project.languages().clone());
         let action_log = cx.new(|_| ActionLog::new(project.clone()));
         let model = Arc::new(FakeLanguageModel::default());
-        let thread = cx.new(|cx| {
-            Thread::new(
-                project,
-                Rc::default(),
-                context_server_registry,
-                action_log.clone(),
-                Templates::new(),
-                Some(model.clone()),
-                cx,
-            )
-        });
+        let thread = cx.new(|cx| Thread::test(model.clone(), project, action_log, cx));
 
         // First, test with remove_trailing_whitespace_on_save enabled
         cx.update(|cx| {
@@ -887,9 +886,10 @@ mod tests {
                     path: "root/src/main.rs".into(),
                     mode: EditFileMode::Overwrite,
                 };
-                Arc::new(EditFileTool {
-                    thread: thread.clone(),
-                })
+                Arc::new(EditFileTool::new(
+                    thread.downgrade(),
+                    language_registry.clone(),
+                ))
                 .run(input, ToolCallEventStream::test().0, cx)
             });
 
@@ -938,10 +938,11 @@ mod tests {
                     path: "root/src/main.rs".into(),
                     mode: EditFileMode::Overwrite,
                 };
-                Arc::new(EditFileTool {
-                    thread: thread.clone(),
-                })
-                .run(input, ToolCallEventStream::test().0, cx)
+                Arc::new(EditFileTool::new(thread.downgrade(), language_registry)).run(
+                    input,
+                    ToolCallEventStream::test().0,
+                    cx,
+                )
             });
 
             // Stream the content with trailing whitespace
@@ -974,22 +975,12 @@ mod tests {
         init_test(cx);
         let fs = project::FakeFs::new(cx.executor());
         let project = Project::test(fs.clone(), [path!("/root").as_ref()], cx).await;
-        let context_server_registry =
-            cx.new(|cx| ContextServerRegistry::new(project.read(cx).context_server_store(), cx));
+        let language_registry = project.read_with(cx, |project, _cx| project.languages().clone());
         let action_log = cx.new(|_| ActionLog::new(project.clone()));
         let model = Arc::new(FakeLanguageModel::default());
-        let thread = cx.new(|cx| {
-            Thread::new(
-                project,
-                Rc::default(),
-                context_server_registry,
-                action_log.clone(),
-                Templates::new(),
-                Some(model.clone()),
-                cx,
-            )
-        });
-        let tool = Arc::new(EditFileTool { thread });
+        let thread = cx.new(|cx| Thread::test(model, project, action_log, cx));
+
+        let tool = Arc::new(EditFileTool::new(thread.downgrade(), language_registry));
         fs.insert_tree("/root", json!({})).await;
 
         // Test 1: Path with .zed component should require confirmation
@@ -1111,22 +1102,12 @@ mod tests {
         let fs = project::FakeFs::new(cx.executor());
         fs.insert_tree("/project", json!({})).await;
         let project = Project::test(fs.clone(), [path!("/project").as_ref()], cx).await;
-        let context_server_registry =
-            cx.new(|cx| ContextServerRegistry::new(project.read(cx).context_server_store(), cx));
+        let language_registry = project.read_with(cx, |project, _cx| project.languages().clone());
         let action_log = cx.new(|_| ActionLog::new(project.clone()));
         let model = Arc::new(FakeLanguageModel::default());
-        let thread = cx.new(|cx| {
-            Thread::new(
-                project,
-                Rc::default(),
-                context_server_registry,
-                action_log.clone(),
-                Templates::new(),
-                Some(model.clone()),
-                cx,
-            )
-        });
-        let tool = Arc::new(EditFileTool { thread });
+        let thread = cx.new(|cx| Thread::test(model, project, action_log, cx));
+
+        let tool = Arc::new(EditFileTool::new(thread.downgrade(), language_registry));
 
         // Test global config paths - these should require confirmation if they exist and are outside the project
         let test_cases = vec![
@@ -1220,23 +1201,12 @@ mod tests {
             cx,
         )
         .await;
-
+        let language_registry = project.read_with(cx, |project, _cx| project.languages().clone());
         let action_log = cx.new(|_| ActionLog::new(project.clone()));
-        let context_server_registry =
-            cx.new(|cx| ContextServerRegistry::new(project.read(cx).context_server_store(), cx));
         let model = Arc::new(FakeLanguageModel::default());
-        let thread = cx.new(|cx| {
-            Thread::new(
-                project.clone(),
-                Rc::default(),
-                context_server_registry.clone(),
-                action_log.clone(),
-                Templates::new(),
-                Some(model.clone()),
-                cx,
-            )
-        });
-        let tool = Arc::new(EditFileTool { thread });
+        let thread = cx.new(|cx| Thread::test(model, project, action_log, cx));
+
+        let tool = Arc::new(EditFileTool::new(thread.downgrade(), language_registry));
 
         // Test files in different worktrees
         let test_cases = vec![
@@ -1302,22 +1272,12 @@ mod tests {
         )
         .await;
         let project = Project::test(fs.clone(), [path!("/project").as_ref()], cx).await;
+        let language_registry = project.read_with(cx, |project, _cx| project.languages().clone());
         let action_log = cx.new(|_| ActionLog::new(project.clone()));
-        let context_server_registry =
-            cx.new(|cx| ContextServerRegistry::new(project.read(cx).context_server_store(), cx));
         let model = Arc::new(FakeLanguageModel::default());
-        let thread = cx.new(|cx| {
-            Thread::new(
-                project.clone(),
-                Rc::default(),
-                context_server_registry.clone(),
-                action_log.clone(),
-                Templates::new(),
-                Some(model.clone()),
-                cx,
-            )
-        });
-        let tool = Arc::new(EditFileTool { thread });
+        let thread = cx.new(|cx| Thread::test(model, project, action_log, cx));
+
+        let tool = Arc::new(EditFileTool::new(thread.downgrade(), language_registry));
 
         // Test edge cases
         let test_cases = vec![
@@ -1386,22 +1346,12 @@ mod tests {
         )
         .await;
         let project = Project::test(fs.clone(), [path!("/project").as_ref()], cx).await;
+        let language_registry = project.read_with(cx, |project, _cx| project.languages().clone());
         let action_log = cx.new(|_| ActionLog::new(project.clone()));
-        let context_server_registry =
-            cx.new(|cx| ContextServerRegistry::new(project.read(cx).context_server_store(), cx));
         let model = Arc::new(FakeLanguageModel::default());
-        let thread = cx.new(|cx| {
-            Thread::new(
-                project.clone(),
-                Rc::default(),
-                context_server_registry.clone(),
-                action_log.clone(),
-                Templates::new(),
-                Some(model.clone()),
-                cx,
-            )
-        });
-        let tool = Arc::new(EditFileTool { thread });
+        let thread = cx.new(|cx| Thread::test(model, project, action_log, cx));
+
+        let tool = Arc::new(EditFileTool::new(thread.downgrade(), language_registry));
 
         // Test different EditFileMode values
         let modes = vec![
@@ -1467,22 +1417,12 @@ mod tests {
         init_test(cx);
         let fs = project::FakeFs::new(cx.executor());
         let project = Project::test(fs.clone(), [path!("/project").as_ref()], cx).await;
+        let language_registry = project.read_with(cx, |project, _cx| project.languages().clone());
         let action_log = cx.new(|_| ActionLog::new(project.clone()));
-        let context_server_registry =
-            cx.new(|cx| ContextServerRegistry::new(project.read(cx).context_server_store(), cx));
         let model = Arc::new(FakeLanguageModel::default());
-        let thread = cx.new(|cx| {
-            Thread::new(
-                project.clone(),
-                Rc::default(),
-                context_server_registry,
-                action_log.clone(),
-                Templates::new(),
-                Some(model.clone()),
-                cx,
-            )
-        });
-        let tool = Arc::new(EditFileTool { thread });
+        let thread = cx.new(|cx| Thread::test(model, project, action_log, cx));
+
+        let tool = Arc::new(EditFileTool::new(thread.downgrade(), language_registry));
 
         assert_eq!(
             tool.initial_title(Err(json!({

crates/agent2/src/tools/terminal_tool.rs

@@ -319,7 +319,7 @@ mod tests {
     use theme::ThemeSettings;
     use util::test::TempTree;
 
-    use crate::AgentResponseEvent;
+    use crate::ThreadEvent;
 
     use super::*;
 
@@ -396,7 +396,7 @@ mod tests {
             });
             cx.run_until_parked();
             let event = stream_rx.try_next();
-            if let Ok(Some(Ok(AgentResponseEvent::ToolCallAuthorization(auth)))) = event {
+            if let Ok(Some(Ok(ThreadEvent::ToolCallAuthorization(auth)))) = event {
                 auth.response.send(auth.options[0].id.clone()).unwrap();
             }
 

crates/agent2/src/tools/web_search_tool.rs

@@ -80,33 +80,48 @@ impl AgentTool for WebSearchTool {
                 }
             };
 
-            let result_text = if response.results.len() == 1 {
-                "1 result".to_string()
-            } else {
-                format!("{} results", response.results.len())
-            };
-            event_stream.update_fields(acp::ToolCallUpdateFields {
-                title: Some(format!("Searched the web: {result_text}")),
-                content: Some(
-                    response
-                        .results
-                        .iter()
-                        .map(|result| acp::ToolCallContent::Content {
-                            content: acp::ContentBlock::ResourceLink(acp::ResourceLink {
-                                name: result.title.clone(),
-                                uri: result.url.clone(),
-                                title: Some(result.title.clone()),
-                                description: Some(result.text.clone()),
-                                mime_type: None,
-                                annotations: None,
-                                size: None,
-                            }),
-                        })
-                        .collect(),
-                ),
-                ..Default::default()
-            });
+            emit_update(&response, &event_stream);
             Ok(WebSearchToolOutput(response))
         })
     }
+
+    fn replay(
+        &self,
+        _input: Self::Input,
+        output: Self::Output,
+        event_stream: ToolCallEventStream,
+        _cx: &mut App,
+    ) -> Result<()> {
+        emit_update(&output.0, &event_stream);
+        Ok(())
+    }
+}
+
+fn emit_update(response: &WebSearchResponse, event_stream: &ToolCallEventStream) {
+    let result_text = if response.results.len() == 1 {
+        "1 result".to_string()
+    } else {
+        format!("{} results", response.results.len())
+    };
+    event_stream.update_fields(acp::ToolCallUpdateFields {
+        title: Some(format!("Searched the web: {result_text}")),
+        content: Some(
+            response
+                .results
+                .iter()
+                .map(|result| acp::ToolCallContent::Content {
+                    content: acp::ContentBlock::ResourceLink(acp::ResourceLink {
+                        name: result.title.clone(),
+                        uri: result.url.clone(),
+                        title: Some(result.title.clone()),
+                        description: Some(result.text.clone()),
+                        mime_type: None,
+                        annotations: None,
+                        size: None,
+                    }),
+                })
+                .collect(),
+        ),
+        ..Default::default()
+    });
 }

crates/agent_servers/src/acp.rs

@@ -1,7 +1,7 @@
 use std::{path::Path, rc::Rc};
 
 use crate::AgentServerCommand;
-use acp_thread::AgentConnection;
+use acp_thread::{AgentConnection, AgentServerName};
 use anyhow::Result;
 use gpui::AsyncApp;
 use thiserror::Error;
@@ -14,12 +14,12 @@ mod v1;
 pub struct UnsupportedVersion;
 
 pub async fn connect(
-    server_name: &'static str,
+    server_name: AgentServerName,
     command: AgentServerCommand,
     root_dir: &Path,
     cx: &mut AsyncApp,
 ) -> Result<Rc<dyn AgentConnection>> {
-    let conn = v1::AcpConnection::stdio(server_name, command.clone(), &root_dir, cx).await;
+    let conn = v1::AcpConnection::stdio(server_name.clone(), command.clone(), &root_dir, cx).await;
 
     match conn {
         Ok(conn) => Ok(Rc::new(conn) as _),

crates/agent_servers/src/acp/v0.rs

@@ -10,7 +10,7 @@ use ui::App;
 use util::ResultExt as _;
 
 use crate::AgentServerCommand;
-use acp_thread::{AcpThread, AgentConnection, AuthRequired};
+use acp_thread::{AcpThread, AgentConnection, AgentServerName, AuthRequired};
 
 #[derive(Clone)]
 struct OldAcpClientDelegate {
@@ -354,7 +354,7 @@ fn into_new_plan_status(status: acp_old::PlanEntryStatus) -> acp::PlanEntryStatu
 }
 
 pub struct AcpConnection {
-    pub name: &'static str,
+    pub name: AgentServerName,
     pub connection: acp_old::AgentConnection,
     pub _child_status: Task<Result<()>>,
     pub current_thread: Rc<RefCell<WeakEntity<AcpThread>>>,
@@ -362,7 +362,7 @@ pub struct AcpConnection {
 
 impl AcpConnection {
     pub fn stdio(
-        name: &'static str,
+        name: AgentServerName,
         command: AgentServerCommand,
         root_dir: &Path,
         cx: &mut AsyncApp,
@@ -443,7 +443,7 @@ impl AgentConnection for AcpConnection {
             cx.update(|cx| {
                 let thread = cx.new(|cx| {
                     let session_id = acp::SessionId("acp-old-no-id".into());
-                    AcpThread::new(self.name, self.clone(), project, session_id, cx)
+                    AcpThread::new(self.name.0.clone(), self.clone(), project, session_id, cx)
                 });
                 current_thread.replace(thread.downgrade());
                 thread

crates/agent_servers/src/acp/v1.rs

@@ -13,10 +13,10 @@ use anyhow::{Context as _, Result};
 use gpui::{App, AppContext as _, AsyncApp, Entity, Task, WeakEntity};
 
 use crate::{AgentServerCommand, acp::UnsupportedVersion};
-use acp_thread::{AcpThread, AgentConnection, AuthRequired};
+use acp_thread::{AcpThread, AgentConnection, AgentServerName, AuthRequired};
 
 pub struct AcpConnection {
-    server_name: &'static str,
+    server_name: AgentServerName,
     connection: Rc<acp::ClientSideConnection>,
     sessions: Rc<RefCell<HashMap<acp::SessionId, AcpSession>>>,
     auth_methods: Vec<acp::AuthMethod>,
@@ -31,7 +31,7 @@ const MINIMUM_SUPPORTED_VERSION: acp::ProtocolVersion = acp::V1;
 
 impl AcpConnection {
     pub async fn stdio(
-        server_name: &'static str,
+        server_name: AgentServerName,
         command: AgentServerCommand,
         root_dir: &Path,
         cx: &mut AsyncApp,
@@ -150,7 +150,7 @@ impl AgentConnection for AcpConnection {
 
             let thread = cx.new(|cx| {
                 AcpThread::new(
-                    self.server_name,
+                    self.server_name.0.clone(),
                     self.clone(),
                     project,
                     session_id.clone(),

crates/agent_servers/src/agent_servers.rs

@@ -10,7 +10,7 @@ pub use claude::*;
 pub use gemini::*;
 pub use settings::*;
 
-use acp_thread::AgentConnection;
+use acp_thread::{AgentConnection, AgentServerName};
 use anyhow::Result;
 use collections::HashMap;
 use gpui::{App, AsyncApp, Entity, SharedString, Task};
@@ -30,7 +30,7 @@ pub fn init(cx: &mut App) {
 
 pub trait AgentServer: Send {
     fn logo(&self) -> ui::IconName;
-    fn name(&self) -> &'static str;
+    fn name(&self) -> AgentServerName;
     fn empty_state_headline(&self) -> &'static str;
     fn empty_state_message(&self) -> &'static str;
 

crates/agent_servers/src/claude.rs

@@ -30,18 +30,18 @@ use util::{ResultExt, debug_panic};
 use crate::claude::mcp_server::{ClaudeZedMcpServer, McpConfig};
 use crate::claude::tools::ClaudeTool;
 use crate::{AgentServer, AgentServerCommand, AllAgentServersSettings};
-use acp_thread::{AcpThread, AgentConnection};
+use acp_thread::{AcpThread, AgentConnection, AgentServerName};
 
 #[derive(Clone)]
 pub struct ClaudeCode;
 
 impl AgentServer for ClaudeCode {
-    fn name(&self) -> &'static str {
-        "Claude Code"
+    fn name(&self) -> AgentServerName {
+        AgentServerName("Claude Code".into())
     }
 
     fn empty_state_headline(&self) -> &'static str {
-        self.name()
+        "Claude Code"
     }
 
     fn empty_state_message(&self) -> &'static str {

crates/agent_servers/src/gemini.rs

@@ -2,7 +2,7 @@ use std::path::Path;
 use std::rc::Rc;
 
 use crate::{AgentServer, AgentServerCommand};
-use acp_thread::{AgentConnection, LoadError};
+use acp_thread::{AgentConnection, AgentServerName, LoadError};
 use anyhow::Result;
 use gpui::{Entity, Task};
 use project::Project;
@@ -17,8 +17,8 @@ pub struct Gemini;
 const ACP_ARG: &str = "--experimental-acp";
 
 impl AgentServer for Gemini {
-    fn name(&self) -> &'static str {
-        "Gemini"
+    fn name(&self) -> AgentServerName {
+        AgentServerName("Gemini".into())
     }
 
     fn empty_state_headline(&self) -> &'static str {

crates/agent_ui/src/acp.rs

@@ -3,8 +3,10 @@ mod entry_view_state;
 mod message_editor;
 mod model_selector;
 mod model_selector_popover;
+mod thread_history;
 mod thread_view;
 
 pub use model_selector::AcpModelSelector;
 pub use model_selector_popover::AcpModelSelectorPopover;
+pub use thread_history::{AcpThreadHistory, ThreadHistoryEvent};
 pub use thread_view::AcpThreadView;

crates/agent_ui/src/acp/thread_history.rs

@@ -0,0 +1,796 @@
+use crate::RemoveSelectedThread;
+use agent_servers::AgentServer;
+use agent2::{HistoryEntry, HistoryStore, NativeAgentServer};
+use chrono::{Datelike as _, Local, NaiveDate, TimeDelta};
+use editor::{Editor, EditorEvent};
+use fuzzy::{StringMatch, StringMatchCandidate};
+use gpui::{
+    App, Empty, Entity, EventEmitter, FocusHandle, Focusable, Global, ScrollStrategy, Stateful,
+    Task, UniformListScrollHandle, Window, uniform_list,
+};
+use project::Project;
+use std::{fmt::Display, ops::Range, sync::Arc};
+use time::{OffsetDateTime, UtcOffset};
+use ui::{
+    HighlightedLabel, IconButtonShape, ListItem, ListItemSpacing, Scrollbar, ScrollbarState,
+    Tooltip, prelude::*,
+};
+use util::ResultExt;
+
+pub struct AcpThreadHistory {
+    pub(crate) history_store: Entity<HistoryStore>,
+    scroll_handle: UniformListScrollHandle,
+    selected_index: usize,
+    hovered_index: Option<usize>,
+    search_editor: Entity<Editor>,
+    all_entries: Arc<Vec<HistoryEntry>>,
+    // When the search is empty, we display date separators between history entries
+    // This vector contains an enum of either a separator or an actual entry
+    separated_items: Vec<ListItemType>,
+    // Maps entry indexes to list item indexes
+    separated_item_indexes: Vec<u32>,
+    _separated_items_task: Option<Task<()>>,
+    search_state: SearchState,
+    scrollbar_visibility: bool,
+    scrollbar_state: ScrollbarState,
+    local_timezone: UtcOffset,
+    _subscriptions: Vec<gpui::Subscription>,
+}
+
+enum SearchState {
+    Empty,
+    Searching {
+        query: SharedString,
+        _task: Task<()>,
+    },
+    Searched {
+        query: SharedString,
+        matches: Vec<StringMatch>,
+    },
+}
+
+enum ListItemType {
+    BucketSeparator(TimeBucket),
+    Entry {
+        index: usize,
+        format: EntryTimeFormat,
+    },
+}
+
+pub enum ThreadHistoryEvent {
+    Open(HistoryEntry),
+}
+
+impl EventEmitter<ThreadHistoryEvent> for AcpThreadHistory {}
+
+impl AcpThreadHistory {
+    pub(crate) fn new(
+        project: &Entity<Project>,
+        window: &mut Window,
+        cx: &mut Context<Self>,
+    ) -> Self {
+        let search_editor = cx.new(|cx| {
+            let mut editor = Editor::single_line(window, cx);
+            editor.set_placeholder_text("Search threads...", cx);
+            editor
+        });
+        let history_store = HistoryStore::get_or_init(project, cx);
+
+        let search_editor_subscription =
+            cx.subscribe(&search_editor, |this, search_editor, event, cx| {
+                if let EditorEvent::BufferEdited = event {
+                    let query = search_editor.read(cx).text(cx);
+                    this.search(query.into(), cx);
+                }
+            });
+
+        let history_store_subscription = cx.observe(&history_store, |this, _, cx| {
+            this.update_all_entries(cx);
+        });
+
+        let scroll_handle = UniformListScrollHandle::default();
+        let scrollbar_state = ScrollbarState::new(scroll_handle.clone());
+
+        let mut this = Self {
+            history_store,
+            scroll_handle,
+            selected_index: 0,
+            hovered_index: None,
+            search_state: SearchState::Empty,
+            all_entries: Default::default(),
+            separated_items: Default::default(),
+            separated_item_indexes: Default::default(),
+            search_editor,
+            scrollbar_visibility: true,
+            scrollbar_state,
+            local_timezone: UtcOffset::from_whole_seconds(
+                chrono::Local::now().offset().local_minus_utc(),
+            )
+            .unwrap(),
+            _subscriptions: vec![search_editor_subscription, history_store_subscription],
+            _separated_items_task: None,
+        };
+        this.update_all_entries(cx);
+        this
+    }
+
+    fn update_all_entries(&mut self, cx: &mut Context<Self>) {
+        let new_entries: Arc<Vec<HistoryEntry>> = self
+            .history_store
+            .update(cx, |store, cx| store.entries(cx))
+            .into();
+
+        self._separated_items_task.take();
+
+        let mut items = Vec::with_capacity(new_entries.len() + 1);
+        let mut indexes = Vec::with_capacity(new_entries.len() + 1);
+
+        let bg_task = cx.background_spawn(async move {
+            let mut bucket = None;
+            let today = Local::now().naive_local().date();
+
+            for (index, entry) in new_entries.iter().enumerate() {
+                let entry_date = entry
+                    .updated_at()
+                    .with_timezone(&Local)
+                    .naive_local()
+                    .date();
+                let entry_bucket = TimeBucket::from_dates(today, entry_date);
+
+                if Some(entry_bucket) != bucket {
+                    bucket = Some(entry_bucket);
+                    items.push(ListItemType::BucketSeparator(entry_bucket));
+                }
+
+                indexes.push(items.len() as u32);
+                items.push(ListItemType::Entry {
+                    index,
+                    format: entry_bucket.into(),
+                });
+            }
+            (new_entries, items, indexes)
+        });
+
+        let task = cx.spawn(async move |this, cx| {
+            let (new_entries, items, indexes) = bg_task.await;
+            this.update(cx, |this, cx| {
+                let previously_selected_entry =
+                    this.all_entries.get(this.selected_index).map(|e| e.id());
+
+                this.all_entries = new_entries;
+                this.separated_items = items;
+                this.separated_item_indexes = indexes;
+
+                match &this.search_state {
+                    SearchState::Empty => {
+                        if this.selected_index >= this.all_entries.len() {
+                            this.set_selected_entry_index(
+                                this.all_entries.len().saturating_sub(1),
+                                cx,
+                            );
+                        } else if let Some(prev_id) = previously_selected_entry {
+                            if let Some(new_ix) = this
+                                .all_entries
+                                .iter()
+                                .position(|probe| probe.id() == prev_id)
+                            {
+                                this.set_selected_entry_index(new_ix, cx);
+                            }
+                        }
+                    }
+                    SearchState::Searching { query, .. } | SearchState::Searched { query, .. } => {
+                        this.search(query.clone(), cx);
+                    }
+                }
+
+                cx.notify();
+            })
+            .log_err();
+        });
+        self._separated_items_task = Some(task);
+    }
+
+    fn search(&mut self, query: SharedString, cx: &mut Context<Self>) {
+        if query.is_empty() {
+            self.search_state = SearchState::Empty;
+            cx.notify();
+            return;
+        }
+
+        let all_entries = self.all_entries.clone();
+
+        let fuzzy_search_task = cx.background_spawn({
+            let query = query.clone();
+            let executor = cx.background_executor().clone();
+            async move {
+                let mut candidates = Vec::with_capacity(all_entries.len());
+
+                for (idx, entry) in all_entries.iter().enumerate() {
+                    match entry {
+                        HistoryEntry::AcpThread(thread) => {
+                            candidates.push(StringMatchCandidate::new(idx, &thread.title));
+                        }
+                        HistoryEntry::TextThread(context) => {
+                            candidates.push(StringMatchCandidate::new(idx, &context.title));
+                        }
+                    }
+                }
+
+                const MAX_MATCHES: usize = 100;
+
+                fuzzy::match_strings(
+                    &candidates,
+                    &query,
+                    false,
+                    true,
+                    MAX_MATCHES,
+                    &Default::default(),
+                    executor,
+                )
+                .await
+            }
+        });
+
+        let task = cx.spawn({
+            let query = query.clone();
+            async move |this, cx| {
+                let matches = fuzzy_search_task.await;
+
+                this.update(cx, |this, cx| {
+                    let SearchState::Searching {
+                        query: current_query,
+                        _task,
+                    } = &this.search_state
+                    else {
+                        return;
+                    };
+
+                    if &query == current_query {
+                        this.search_state = SearchState::Searched {
+                            query: query.clone(),
+                            matches,
+                        };
+
+                        this.set_selected_entry_index(0, cx);
+                        cx.notify();
+                    };
+                })
+                .log_err();
+            }
+        });
+
+        self.search_state = SearchState::Searching { query, _task: task };
+        cx.notify();
+    }
+
+    fn matched_count(&self) -> usize {
+        match &self.search_state {
+            SearchState::Empty => self.all_entries.len(),
+            SearchState::Searching { .. } => 0,
+            SearchState::Searched { matches, .. } => matches.len(),
+        }
+    }
+
+    fn list_item_count(&self) -> usize {
+        match &self.search_state {
+            SearchState::Empty => self.separated_items.len(),
+            SearchState::Searching { .. } => 0,
+            SearchState::Searched { matches, .. } => matches.len(),
+        }
+    }
+
+    fn search_produced_no_matches(&self) -> bool {
+        match &self.search_state {
+            SearchState::Empty => false,
+            SearchState::Searching { .. } => false,
+            SearchState::Searched { matches, .. } => matches.is_empty(),
+        }
+    }
+
+    fn get_match(&self, ix: usize) -> Option<&HistoryEntry> {
+        match &self.search_state {
+            SearchState::Empty => self.all_entries.get(ix),
+            SearchState::Searching { .. } => None,
+            SearchState::Searched { matches, .. } => matches
+                .get(ix)
+                .and_then(|m| self.all_entries.get(m.candidate_id)),
+        }
+    }
+
+    pub fn select_previous(
+        &mut self,
+        _: &menu::SelectPrevious,
+        _window: &mut Window,
+        cx: &mut Context<Self>,
+    ) {
+        let count = self.matched_count();
+        if count > 0 {
+            if self.selected_index == 0 {
+                self.set_selected_entry_index(count - 1, cx);
+            } else {
+                self.set_selected_entry_index(self.selected_index - 1, cx);
+            }
+        }
+    }
+
+    pub fn select_next(
+        &mut self,
+        _: &menu::SelectNext,
+        _window: &mut Window,
+        cx: &mut Context<Self>,
+    ) {
+        let count = self.matched_count();
+        if count > 0 {
+            if self.selected_index == count - 1 {
+                self.set_selected_entry_index(0, cx);
+            } else {
+                self.set_selected_entry_index(self.selected_index + 1, cx);
+            }
+        }
+    }
+
+    fn select_first(
+        &mut self,
+        _: &menu::SelectFirst,
+        _window: &mut Window,
+        cx: &mut Context<Self>,
+    ) {
+        let count = self.matched_count();
+        if count > 0 {
+            self.set_selected_entry_index(0, cx);
+        }
+    }
+
+    fn select_last(&mut self, _: &menu::SelectLast, _window: &mut Window, cx: &mut Context<Self>) {
+        let count = self.matched_count();
+        if count > 0 {
+            self.set_selected_entry_index(count - 1, cx);
+        }
+    }
+
+    fn set_selected_entry_index(&mut self, entry_index: usize, cx: &mut Context<Self>) {
+        self.selected_index = entry_index;
+
+        let scroll_ix = match self.search_state {
+            SearchState::Empty | SearchState::Searching { .. } => self
+                .separated_item_indexes
+                .get(entry_index)
+                .map(|ix| *ix as usize)
+                .unwrap_or(entry_index + 1),
+            SearchState::Searched { .. } => entry_index,
+        };
+
+        self.scroll_handle
+            .scroll_to_item(scroll_ix, ScrollStrategy::Top);
+
+        cx.notify();
+    }
+
+    fn render_scrollbar(&self, cx: &mut Context<Self>) -> Option<Stateful<Div>> {
+        if !(self.scrollbar_visibility || self.scrollbar_state.is_dragging()) {
+            return None;
+        }
+
+        Some(
+            div()
+                .occlude()
+                .id("thread-history-scroll")
+                .h_full()
+                .bg(cx.theme().colors().panel_background.opacity(0.8))
+                .border_l_1()
+                .border_color(cx.theme().colors().border_variant)
+                .absolute()
+                .right_1()
+                .top_0()
+                .bottom_0()
+                .w_4()
+                .pl_1()
+                .cursor_default()
+                .on_mouse_move(cx.listener(|_, _, _window, cx| {
+                    cx.notify();
+                    cx.stop_propagation()
+                }))
+                .on_hover(|_, _window, cx| {
+                    cx.stop_propagation();
+                })
+                .on_any_mouse_down(|_, _window, cx| {
+                    cx.stop_propagation();
+                })
+                .on_scroll_wheel(cx.listener(|_, _, _window, cx| {
+                    cx.notify();
+                }))
+                .children(Scrollbar::vertical(self.scrollbar_state.clone())),
+        )
+    }
+
+    fn confirm(&mut self, _: &menu::Confirm, _window: &mut Window, cx: &mut Context<Self>) {
+        self.confirm_entry(self.selected_index, cx);
+    }
+
+    fn confirm_entry(&mut self, ix: usize, cx: &mut Context<Self>) {
+        let Some(entry) = self.get_match(ix) else {
+            return;
+        };
+        cx.emit(ThreadHistoryEvent::Open(entry.clone()));
+        // let task_result = match entry {
+        //     HistoryEntry::Thread(thread) => {
+        //         self.agent_panel.update(cx, move |agent_panel, cx| todo!())
+        //     }
+        //     HistoryEntry::Context(context) => {
+        //         self.agent_panel.update(cx, move |agent_panel, cx| {
+        //             agent_panel.open_saved_prompt_editor(context.path.clone(), window, cx)
+        //         })
+        //     }
+        // };
+
+        // if let Some(task) = task_result.log_err() {
+        //     task.detach_and_log_err(cx);
+        // };
+
+        cx.notify();
+    }
+
+    fn remove_selected_thread(
+        &mut self,
+        _: &RemoveSelectedThread,
+        _window: &mut Window,
+        cx: &mut Context<Self>,
+    ) {
+        self.remove_thread(self.selected_index, cx)
+    }
+
+    fn remove_thread(&mut self, ix: usize, cx: &mut Context<Self>) {
+        let Some(entry) = self.get_match(ix) else {
+            return;
+        };
+        todo!();
+        // let task_result = match entry {
+        //     HistoryEntry::Thread(thread) => todo!(),
+        //     HistoryEntry::Context(context) => self
+        //         .agent_panel
+        //         .update(cx, |this, cx| this.delete_context(context.path.clone(), cx)),
+        // };
+
+        // if let Some(task) = task_result.log_err() {
+        //     task.detach_and_log_err(cx);
+        // };
+
+        cx.notify();
+    }
+
+    fn list_items(
+        &mut self,
+        range: Range<usize>,
+        _window: &mut Window,
+        cx: &mut Context<Self>,
+    ) -> Vec<AnyElement> {
+        match &self.search_state {
+            SearchState::Empty => self
+                .separated_items
+                .get(range)
+                .iter()
+                .flat_map(|items| {
+                    items
+                        .iter()
+                        .map(|item| self.render_list_item(item, vec![], cx))
+                })
+                .collect(),
+            SearchState::Searched { matches, .. } => matches[range]
+                .iter()
+                .filter_map(|m| {
+                    let entry = self.all_entries.get(m.candidate_id)?;
+                    Some(self.render_history_entry(
+                        entry,
+                        EntryTimeFormat::DateAndTime,
+                        m.candidate_id,
+                        m.positions.clone(),
+                        cx,
+                    ))
+                })
+                .collect(),
+            SearchState::Searching { .. } => {
+                vec![]
+            }
+        }
+    }
+
+    fn render_list_item(
+        &self,
+        item: &ListItemType,
+        highlight_positions: Vec<usize>,
+        cx: &Context<Self>,
+    ) -> AnyElement {
+        match item {
+            ListItemType::Entry { index, format } => match self.all_entries.get(*index) {
+                Some(entry) => self
+                    .render_history_entry(entry, *format, *index, highlight_positions, cx)
+                    .into_any(),
+                None => Empty.into_any_element(),
+            },
+            ListItemType::BucketSeparator(bucket) => div()
+                .px(DynamicSpacing::Base06.rems(cx))
+                .pt_2()
+                .pb_1()
+                .child(
+                    Label::new(bucket.to_string())
+                        .size(LabelSize::XSmall)
+                        .color(Color::Muted),
+                )
+                .into_any_element(),
+        }
+    }
+
+    fn render_history_entry(
+        &self,
+        entry: &HistoryEntry,
+        format: EntryTimeFormat,
+        list_entry_ix: usize,
+        highlight_positions: Vec<usize>,
+        cx: &Context<Self>,
+    ) -> AnyElement {
+        let selected = list_entry_ix == self.selected_index;
+        let hovered = Some(list_entry_ix) == self.hovered_index;
+        let timestamp = entry.updated_at().timestamp();
+        let thread_timestamp = format.format_timestamp(timestamp, self.local_timezone);
+
+        h_flex()
+            .w_full()
+            .pb_1()
+            .child(
+                ListItem::new(list_entry_ix)
+                    .rounded()
+                    .toggle_state(selected)
+                    .spacing(ListItemSpacing::Sparse)
+                    .start_slot(
+                        h_flex()
+                            .w_full()
+                            .gap_2()
+                            .justify_between()
+                            .child(
+                                HighlightedLabel::new(entry.title(), highlight_positions)
+                                    .size(LabelSize::Small)
+                                    .truncate(),
+                            )
+                            .child(
+                                Label::new(thread_timestamp)
+                                    .color(Color::Muted)
+                                    .size(LabelSize::XSmall),
+                            ),
+                    )
+                    .on_hover(cx.listener(move |this, is_hovered, _window, cx| {
+                        if *is_hovered {
+                            this.hovered_index = Some(list_entry_ix);
+                        } else if this.hovered_index == Some(list_entry_ix) {
+                            this.hovered_index = None;
+                        }
+
+                        cx.notify();
+                    }))
+                    .end_slot::<IconButton>(if hovered || selected {
+                        Some(
+                            IconButton::new("delete", IconName::Trash)
+                                .shape(IconButtonShape::Square)
+                                .icon_size(IconSize::XSmall)
+                                .icon_color(Color::Muted)
+                                .tooltip(move |window, cx| {
+                                    Tooltip::for_action("Delete", &RemoveSelectedThread, window, cx)
+                                })
+                                .on_click(cx.listener(move |this, _, _, cx| {
+                                    this.remove_thread(list_entry_ix, cx)
+                                })),
+                        )
+                    } else {
+                        None
+                    })
+                    .on_click(
+                        cx.listener(move |this, _, _, cx| this.confirm_entry(list_entry_ix, cx)),
+                    ),
+            )
+            .into_any_element()
+    }
+}
+
+impl Focusable for AcpThreadHistory {
+    fn focus_handle(&self, cx: &App) -> FocusHandle {
+        self.search_editor.focus_handle(cx)
+    }
+}
+
+impl Render for AcpThreadHistory {
+    fn render(&mut self, _window: &mut Window, cx: &mut Context<Self>) -> impl IntoElement {
+        v_flex()
+            .key_context("ThreadHistory")
+            .size_full()
+            .on_action(cx.listener(Self::select_previous))
+            .on_action(cx.listener(Self::select_next))
+            .on_action(cx.listener(Self::select_first))
+            .on_action(cx.listener(Self::select_last))
+            .on_action(cx.listener(Self::confirm))
+            .on_action(cx.listener(Self::remove_selected_thread))
+            .when(!self.all_entries.is_empty(), |parent| {
+                parent.child(
+                    h_flex()
+                        .h(px(41.)) // Match the toolbar perfectly
+                        .w_full()
+                        .py_1()
+                        .px_2()
+                        .gap_2()
+                        .justify_between()
+                        .border_b_1()
+                        .border_color(cx.theme().colors().border)
+                        .child(
+                            Icon::new(IconName::MagnifyingGlass)
+                                .color(Color::Muted)
+                                .size(IconSize::Small),
+                        )
+                        .child(self.search_editor.clone()),
+                )
+            })
+            .child({
+                let view = v_flex()
+                    .id("list-container")
+                    .relative()
+                    .overflow_hidden()
+                    .flex_grow();
+
+                if self.all_entries.is_empty() {
+                    view.justify_center()
+                        .child(
+                            h_flex().w_full().justify_center().child(
+                                Label::new("You don't have any past threads yet.")
+                                    .size(LabelSize::Small),
+                            ),
+                        )
+                } else if self.search_produced_no_matches() {
+                    view.justify_center().child(
+                        h_flex().w_full().justify_center().child(
+                            Label::new("No threads match your search.").size(LabelSize::Small),
+                        ),
+                    )
+                } else {
+                    view.pr_5()
+                        .child(
+                            uniform_list(
+                                "thread-history",
+                                self.list_item_count(),
+                                cx.processor(|this, range: Range<usize>, window, cx| {
+                                    this.list_items(range, window, cx)
+                                }),
+                            )
+                            .p_1()
+                            .track_scroll(self.scroll_handle.clone())
+                            .flex_grow(),
+                        )
+                        .when_some(self.render_scrollbar(cx), |div, scrollbar| {
+                            div.child(scrollbar)
+                        })
+                }
+            })
+    }
+}
+
+#[derive(Clone, Copy)]
+pub enum EntryTimeFormat {
+    DateAndTime,
+    TimeOnly,
+}
+
+impl EntryTimeFormat {
+    fn format_timestamp(&self, timestamp: i64, timezone: UtcOffset) -> String {
+        let timestamp = OffsetDateTime::from_unix_timestamp(timestamp).unwrap();
+
+        match self {
+            EntryTimeFormat::DateAndTime => time_format::format_localized_timestamp(
+                timestamp,
+                OffsetDateTime::now_utc(),
+                timezone,
+                time_format::TimestampFormat::EnhancedAbsolute,
+            ),
+            EntryTimeFormat::TimeOnly => time_format::format_time(timestamp),
+        }
+    }
+}
+
+impl From<TimeBucket> for EntryTimeFormat {
+    fn from(bucket: TimeBucket) -> Self {
+        match bucket {
+            TimeBucket::Today => EntryTimeFormat::TimeOnly,
+            TimeBucket::Yesterday => EntryTimeFormat::TimeOnly,
+            TimeBucket::ThisWeek => EntryTimeFormat::DateAndTime,
+            TimeBucket::PastWeek => EntryTimeFormat::DateAndTime,
+            TimeBucket::All => EntryTimeFormat::DateAndTime,
+        }
+    }
+}
+
+#[derive(PartialEq, Eq, Clone, Copy, Debug)]
+enum TimeBucket {
+    Today,
+    Yesterday,
+    ThisWeek,
+    PastWeek,
+    All,
+}
+
+impl TimeBucket {
+    fn from_dates(reference: NaiveDate, date: NaiveDate) -> Self {
+        if date == reference {
+            return TimeBucket::Today;
+        }
+
+        if date == reference - TimeDelta::days(1) {
+            return TimeBucket::Yesterday;
+        }
+
+        let week = date.iso_week();
+
+        if reference.iso_week() == week {
+            return TimeBucket::ThisWeek;
+        }
+
+        let last_week = (reference - TimeDelta::days(7)).iso_week();
+
+        if week == last_week {
+            return TimeBucket::PastWeek;
+        }
+
+        TimeBucket::All
+    }
+}
+
+impl Display for TimeBucket {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            TimeBucket::Today => write!(f, "Today"),
+            TimeBucket::Yesterday => write!(f, "Yesterday"),
+            TimeBucket::ThisWeek => write!(f, "This Week"),
+            TimeBucket::PastWeek => write!(f, "Past Week"),
+            TimeBucket::All => write!(f, "All"),
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use chrono::NaiveDate;
+
+    #[test]
+    fn test_time_bucket_from_dates() {
+        let today = NaiveDate::from_ymd_opt(2023, 1, 15).unwrap();
+
+        let date = today;
+        assert_eq!(TimeBucket::from_dates(today, date), TimeBucket::Today);
+
+        let date = NaiveDate::from_ymd_opt(2023, 1, 14).unwrap();
+        assert_eq!(TimeBucket::from_dates(today, date), TimeBucket::Yesterday);
+
+        let date = NaiveDate::from_ymd_opt(2023, 1, 13).unwrap();
+        assert_eq!(TimeBucket::from_dates(today, date), TimeBucket::ThisWeek);
+
+        let date = NaiveDate::from_ymd_opt(2023, 1, 11).unwrap();
+        assert_eq!(TimeBucket::from_dates(today, date), TimeBucket::ThisWeek);
+
+        let date = NaiveDate::from_ymd_opt(2023, 1, 8).unwrap();
+        assert_eq!(TimeBucket::from_dates(today, date), TimeBucket::PastWeek);
+
+        let date = NaiveDate::from_ymd_opt(2023, 1, 5).unwrap();
+        assert_eq!(TimeBucket::from_dates(today, date), TimeBucket::PastWeek);
+
+        // All: not in this week or last week
+        let date = NaiveDate::from_ymd_opt(2023, 1, 1).unwrap();
+        assert_eq!(TimeBucket::from_dates(today, date), TimeBucket::All);
+
+        // Test year boundary cases
+        let new_year = NaiveDate::from_ymd_opt(2023, 1, 1).unwrap();
+
+        let date = NaiveDate::from_ymd_opt(2022, 12, 31).unwrap();
+        assert_eq!(
+            TimeBucket::from_dates(new_year, date),
+            TimeBucket::Yesterday
+        );
+
+        let date = NaiveDate::from_ymd_opt(2022, 12, 28).unwrap();
+        assert_eq!(TimeBucket::from_dates(new_year, date), TimeBucket::ThisWeek);
+    }
+}

crates/agent_ui/src/acp/thread_view.rs

@@ -1,6 +1,7 @@
 use acp_thread::{
-    AcpThread, AcpThreadEvent, AgentThreadEntry, AssistantMessage, AssistantMessageChunk,
-    LoadError, MentionUri, ThreadStatus, ToolCall, ToolCallContent, ToolCallStatus, UserMessageId,
+    AcpThread, AcpThreadEvent, AcpThreadMetadata, AgentThreadEntry, AssistantMessage,
+    AssistantMessageChunk, LoadError, MentionUri, ThreadStatus, ToolCall, ToolCallContent,
+    ToolCallStatus, UserMessageId,
 };
 use acp_thread::{AgentConnection, Plan};
 use action_log::ActionLog;
@@ -17,6 +18,7 @@ use editor::scroll::Autoscroll;
 use editor::{Editor, EditorMode, MultiBuffer, PathKey, SelectionEffects};
 use file_icons::FileIcons;
 use fs::Fs;
+use futures::StreamExt;
 use gpui::{
     Action, Animation, AnimationExt, App, BorderStyle, ClickEvent, ClipboardItem, EdgesRefinement,
     Empty, Entity, FocusHandle, Focusable, Hsla, Length, ListOffset, ListState, MouseButton,
@@ -122,6 +124,7 @@ pub struct AcpThreadView {
     editor_expanded: bool,
     terminal_expanded: bool,
     editing_message: Option<usize>,
+    history_store: Entity<agent2::HistoryStore>,
     _cancel_task: Option<Task<()>>,
     _subscriptions: [Subscription; 3],
 }
@@ -133,6 +136,7 @@ enum ThreadState {
     Ready {
         thread: Entity<AcpThread>,
         _subscription: [Subscription; 2],
+        _history_task: Option<Task<()>>,
     },
     LoadError(LoadError),
     Unauthenticated {
@@ -148,8 +152,10 @@ impl AcpThreadView {
         agent: Rc<dyn AgentServer>,
         workspace: WeakEntity<Workspace>,
         project: Entity<Project>,
+        history_store: Entity<agent2::HistoryStore>,
         thread_store: Entity<ThreadStore>,
         text_thread_store: Entity<TextThreadStore>,
+        restore_thread: Option<AcpThreadMetadata>,
         window: &mut Window,
         cx: &mut Context<Self>,
     ) -> Self {
@@ -191,7 +197,16 @@ impl AcpThreadView {
             workspace: workspace.clone(),
             project: project.clone(),
             entry_view_state,
-            thread_state: Self::initial_state(agent, workspace, project, window, cx),
+            thread_state: Self::initial_state(
+                agent,
+                restore_thread,
+                history_store.clone(),
+                workspace,
+                project,
+                window,
+                cx,
+            ),
+            history_store,
             message_editor,
             model_selector: None,
             profile_selector: None,
@@ -215,6 +230,8 @@ impl AcpThreadView {
 
     fn initial_state(
         agent: Rc<dyn AgentServer>,
+        restore_thread: Option<AcpThreadMetadata>,
+        history_store: Entity<agent2::HistoryStore>,
         workspace: WeakEntity<Workspace>,
         project: Entity<Project>,
         window: &mut Window,
@@ -241,6 +258,25 @@ impl AcpThreadView {
                 }
             };
 
+            let mut history_task = None;
+            let history = connection.clone().history();
+            if let Some(history) = history.clone() {
+                if let Some(mut history) = cx.update(|_, cx| history.observe_history(cx)).ok() {
+                    history_task = Some(cx.spawn(async move |cx| {
+                        while let Some(update) = history.next().await {
+                            if !history_store
+                                .update(cx, |history_store, cx| {
+                                    history_store.update_history(update, cx)
+                                })
+                                .is_ok()
+                            {
+                                break;
+                            }
+                        }
+                    }));
+                }
+            }
+
             // this.update_in(cx, |_this, _window, cx| {
             //     let status = connection.exit_status(cx);
             //     cx.spawn(async move |this, cx| {
@@ -254,19 +290,24 @@ impl AcpThreadView {
             //     .detach();
             // })
             // .ok();
-
-            let Some(result) = cx
-                .update(|_, cx| {
+            let history = connection.clone().history();
+            let task = cx.update(|_, cx| {
+                if let Some(restore_thread) = restore_thread
+                    && let Some(history) = history
+                {
+                    history.load_thread(project.clone(), &root_dir, restore_thread.id, cx)
+                } else {
                     connection
                         .clone()
                         .new_thread(project.clone(), &root_dir, cx)
-                })
-                .log_err()
-            else {
+                }
+            });
+
+            let Ok(task) = task else {
                 return;
             };
 
-            let result = match result.await {
+            let result = match task.await {
                 Err(e) => {
                     let mut cx = cx.clone();
                     if e.is::<acp_thread::AuthRequired>() {
@@ -293,8 +334,13 @@ impl AcpThreadView {
                         let action_log_subscription =
                             cx.observe(&action_log, |_, _, cx| cx.notify());
 
-                        this.list_state
-                            .splice(0..0, thread.read(cx).entries().len());
+                        let count = thread.read(cx).entries().len();
+                        this.list_state.splice(0..0, count);
+                        this.entry_view_state.update(cx, |view_state, cx| {
+                            for ix in 0..count {
+                                view_state.sync_entry(ix, &thread, window, cx);
+                            }
+                        });
 
                         AgentDiff::set_active_thread(&workspace, thread.clone(), window, cx);
 
@@ -319,6 +365,7 @@ impl AcpThreadView {
                         this.thread_state = ThreadState::Ready {
                             thread,
                             _subscription: [thread_subscription, action_log_subscription],
+                            _history_task: history_task,
                         };
 
                         this.profile_selector = this.as_native_thread(cx).map(|thread| {
@@ -698,6 +745,7 @@ impl AcpThreadView {
             AcpThreadEvent::ServerExited(status) => {
                 self.thread_state = ThreadState::ServerExited { status: *status };
             }
+            AcpThreadEvent::TitleUpdated => {}
         }
         cx.notify();
     }
@@ -726,6 +774,8 @@ impl AcpThreadView {
                     } else {
                         this.thread_state = Self::initial_state(
                             agent,
+                            None, // todo!()
+                            this.history_store.clone(),
                             this.workspace.clone(),
                             project.clone(),
                             window,
@@ -2546,12 +2596,15 @@ impl AcpThreadView {
             return;
         };
 
-        thread.update(cx, |thread, _cx| {
+        thread.update(cx, |thread, cx| {
             let current_mode = thread.completion_mode();
-            thread.set_completion_mode(match current_mode {
-                CompletionMode::Burn => CompletionMode::Normal,
-                CompletionMode::Normal => CompletionMode::Burn,
-            });
+            thread.set_completion_mode(
+                match current_mode {
+                    CompletionMode::Burn => CompletionMode::Normal,
+                    CompletionMode::Normal => CompletionMode::Burn,
+                },
+                cx,
+            );
         });
     }
 
@@ -3265,8 +3318,8 @@ impl AcpThreadView {
                             .tooltip(Tooltip::text("Enable Burn Mode for unlimited tool use."))
                             .on_click({
                                 cx.listener(move |this, _, _window, cx| {
-                                    thread.update(cx, |thread, _cx| {
-                                        thread.set_completion_mode(CompletionMode::Burn);
+                                    thread.update(cx, |thread, cx| {
+                                        thread.set_completion_mode(CompletionMode::Burn, cx);
                                     });
                                     this.resume_chat(cx);
                                 })
@@ -3587,7 +3640,7 @@ fn terminal_command_markdown_style(window: &Window, cx: &App) -> MarkdownStyle {
 
 #[cfg(test)]
 pub(crate) mod tests {
-    use acp_thread::StubAgentConnection;
+    use acp_thread::{AgentServerName, StubAgentConnection};
     use agent::{TextThreadStore, ThreadStore};
     use agent_client_protocol::SessionId;
     use editor::EditorSettings;
@@ -3727,6 +3780,8 @@ pub(crate) mod tests {
             cx.update(|_window, cx| cx.new(|cx| ThreadStore::fake(project.clone(), cx)));
         let text_thread_store =
             cx.update(|_window, cx| cx.new(|cx| TextThreadStore::fake(project.clone(), cx)));
+        let history_store =
+            cx.update(|_window, cx| cx.new(|cx| agent2::HistoryStore::get_or_init(cx)));
 
         let thread_view = cx.update(|window, cx| {
             cx.new(|cx| {
@@ -3734,8 +3789,10 @@ pub(crate) mod tests {
                     Rc::new(agent),
                     workspace.downgrade(),
                     project,
+                    history_store.clone(),
                     thread_store.clone(),
                     text_thread_store.clone(),
+                    None,
                     window,
                     cx,
                 )
@@ -3817,8 +3874,8 @@ pub(crate) mod tests {
             ui::IconName::Ai
         }
 
-        fn name(&self) -> &'static str {
-            "Test"
+        fn name(&self) -> AgentServerName {
+            AgentServerName("Test".into())
         }
 
         fn empty_state_headline(&self) -> &'static str {
@@ -3925,6 +3982,8 @@ pub(crate) mod tests {
             cx.update(|_window, cx| cx.new(|cx| ThreadStore::fake(project.clone(), cx)));
         let text_thread_store =
             cx.update(|_window, cx| cx.new(|cx| TextThreadStore::fake(project.clone(), cx)));
+        let history_store =
+            cx.update(|_window, cx| cx.new(|cx| agent2::HistoryStore::get_or_init(cx)));
 
         let connection = Rc::new(StubAgentConnection::new());
         let thread_view = cx.update(|window, cx| {
@@ -3933,8 +3992,10 @@ pub(crate) mod tests {
                     Rc::new(StubAgentServer::new(connection.as_ref().clone())),
                     workspace.downgrade(),
                     project.clone(),
+                    history_store,
                     thread_store.clone(),
                     text_thread_store.clone(),
+                    None,
                     window,
                     cx,
                 )

crates/agent_ui/src/agent_diff.rs

@@ -199,24 +199,21 @@ impl AgentDiffPane {
         let action_log = thread.action_log(cx).clone();
 
         let mut this = Self {
-            _subscriptions: [
-                Some(
-                    cx.observe_in(&action_log, window, |this, _action_log, window, cx| {
-                        this.update_excerpts(window, cx)
-                    }),
-                ),
+            _subscriptions: vec![
+                cx.observe_in(&action_log, window, |this, _action_log, window, cx| {
+                    this.update_excerpts(window, cx)
+                }),
                 match &thread {
-                    AgentDiffThread::Native(thread) => {
-                        Some(cx.subscribe(&thread, |this, _thread, event, cx| {
-                            this.handle_thread_event(event, cx)
-                        }))
-                    }
-                    AgentDiffThread::AcpThread(_) => None,
+                    AgentDiffThread::Native(thread) => cx
+                        .subscribe(&thread, |this, _thread, event, cx| {
+                            this.handle_native_thread_event(event, cx)
+                        }),
+                    AgentDiffThread::AcpThread(thread) => cx
+                        .subscribe(&thread, |this, _thread, event, cx| {
+                            this.handle_acp_thread_event(event, cx)
+                        }),
                 },
-            ]
-            .into_iter()
-            .flatten()
-            .collect(),
+            ],
             title: SharedString::default(),
             multibuffer,
             editor,
@@ -324,13 +321,20 @@ impl AgentDiffPane {
         }
     }
 
-    fn handle_thread_event(&mut self, event: &ThreadEvent, cx: &mut Context<Self>) {
+    fn handle_native_thread_event(&mut self, event: &ThreadEvent, cx: &mut Context<Self>) {
         match event {
             ThreadEvent::SummaryGenerated => self.update_title(cx),
             _ => {}
         }
     }
 
+    fn handle_acp_thread_event(&mut self, event: &AcpThreadEvent, cx: &mut Context<Self>) {
+        match event {
+            AcpThreadEvent::TitleUpdated => self.update_title(cx),
+            _ => {}
+        }
+    }
+
     pub fn move_to_path(&self, path_key: PathKey, window: &mut Window, cx: &mut App) {
         if let Some(position) = self.multibuffer.read(cx).location_for_path(&path_key, cx) {
             self.editor.update(cx, |editor, cx| {
@@ -1521,7 +1525,8 @@ impl AgentDiff {
                     self.update_reviewing_editors(workspace, window, cx);
                 }
             }
-            AcpThreadEvent::EntriesRemoved(_)
+            AcpThreadEvent::TitleUpdated
+            | AcpThreadEvent::EntriesRemoved(_)
             | AcpThreadEvent::Stopped
             | AcpThreadEvent::ToolAuthorizationRequired
             | AcpThreadEvent::Error

crates/agent_ui/src/agent_panel.rs

@@ -4,11 +4,13 @@ use std::rc::Rc;
 use std::sync::Arc;
 use std::time::Duration;
 
+use acp_thread::AcpThreadMetadata;
 use agent_servers::AgentServer;
+use agent2::HistoryEntry;
 use db::kvp::{Dismissable, KEY_VALUE_STORE};
 use serde::{Deserialize, Serialize};
 
-use crate::NewExternalAgentThread;
+use crate::acp::{AcpThreadHistory, ThreadHistoryEvent};
 use crate::agent_diff::AgentDiffThread;
 use crate::{
     AddContextServer, AgentDiffPane, ContinueThread, ContinueWithBurnMode,
@@ -29,6 +31,7 @@ use crate::{
     thread_history::{HistoryEntryElement, ThreadHistory},
     ui::{AgentOnboardingModal, EndTrialUpsell},
 };
+use crate::{ExternalAgent, NewExternalAgentThread};
 use agent::{
     Thread, ThreadError, ThreadEvent, ThreadId, ThreadSummary, TokenUsageRatio,
     context_store::ContextStore,
@@ -119,7 +122,7 @@ pub fn init(cx: &mut App) {
                     if let Some(panel) = workspace.panel::<AgentPanel>(cx) {
                         workspace.focus_panel::<AgentPanel>(window, cx);
                         panel.update(cx, |panel, cx| {
-                            panel.new_external_thread(action.agent, window, cx)
+                            panel.new_external_thread(action.agent, None, window, cx)
                         });
                     }
                 })
@@ -478,6 +481,7 @@ pub struct AgentPanel {
     previous_view: Option<ActiveView>,
     history_store: Entity<HistoryStore>,
     history: Entity<ThreadHistory>,
+    acp_history: Entity<AcpThreadHistory>,
     hovered_recent_history_item: Option<usize>,
     new_thread_menu_handle: PopoverMenuHandle<ContextMenu>,
     agent_panel_menu_handle: PopoverMenuHandle<ContextMenu>,
@@ -744,6 +748,27 @@ impl AgentPanel {
             )
         });
 
+        let acp_history = cx.new(|cx| AcpThreadHistory::new(&project, window, cx));
+        cx.subscribe_in(
+            &acp_history,
+            window,
+            |this, _, event, window, cx| match event {
+                ThreadHistoryEvent::Open(HistoryEntry::AcpThread(thread)) => {
+                    let agent_choice = match thread.agent.0.as_ref() {
+                        "Claude Code" => Some(ExternalAgent::ClaudeCode),
+                        "Gemini" => Some(ExternalAgent::Gemini),
+                        "Native Agent" => Some(ExternalAgent::NativeAgent),
+                        _ => None,
+                    };
+                    this.new_external_thread(agent_choice, Some(thread.clone()), window, cx);
+                }
+                ThreadHistoryEvent::Open(HistoryEntry::TextThread(thread)) => {
+                    todo!()
+                }
+            },
+        )
+        .detach();
+
         Self {
             active_view,
             workspace,
@@ -765,6 +790,7 @@ impl AgentPanel {
             previous_view: None,
             history_store: history_store.clone(),
             history: cx.new(|cx| ThreadHistory::new(weak_self, history_store, window, cx)),
+            acp_history,
             hovered_recent_history_item: None,
             new_thread_menu_handle: PopoverMenuHandle::default(),
             agent_panel_menu_handle: PopoverMenuHandle::default(),
@@ -954,6 +980,7 @@ impl AgentPanel {
     fn new_external_thread(
         &mut self,
         agent_choice: Option<crate::ExternalAgent>,
+        restore_thread: Option<AcpThreadMetadata>,
         window: &mut Window,
         cx: &mut Context<Self>,
     ) {
@@ -1004,13 +1031,16 @@ impl AgentPanel {
             };
 
             this.update_in(cx, |this, window, cx| {
+                let acp_history_store = this.acp_history.read(cx).history_store.clone();
                 let thread_view = cx.new(|cx| {
                     crate::acp::AcpThreadView::new(
                         server,
                         workspace.clone(),
                         project,
+                        acp_history_store,
                         thread_store.clone(),
                         text_thread_store.clone(),
+                        restore_thread,
                         window,
                         cx,
                     )
@@ -1669,13 +1699,13 @@ impl AgentPanel {
                 window.dispatch_action(NewTextThread.boxed_clone(), cx);
             }
             AgentType::NativeAgent => {
-                self.new_external_thread(Some(crate::ExternalAgent::NativeAgent), window, cx)
+                self.new_external_thread(Some(crate::ExternalAgent::NativeAgent), None, window, cx)
             }
             AgentType::Gemini => {
-                self.new_external_thread(Some(crate::ExternalAgent::Gemini), window, cx)
+                self.new_external_thread(Some(crate::ExternalAgent::Gemini), None, window, cx)
             }
             AgentType::ClaudeCode => {
-                self.new_external_thread(Some(crate::ExternalAgent::ClaudeCode), window, cx)
+                self.new_external_thread(Some(crate::ExternalAgent::ClaudeCode), None, window, cx)
             }
         }
     }
@@ -1686,7 +1716,14 @@ impl Focusable for AgentPanel {
         match &self.active_view {
             ActiveView::Thread { message_editor, .. } => message_editor.focus_handle(cx),
             ActiveView::ExternalAgentThread { thread_view, .. } => thread_view.focus_handle(cx),
-            ActiveView::History => self.history.focus_handle(cx),
+            ActiveView::History => {
+                if cx.has_flag::<feature_flags::AcpFeatureFlag>() {
+                    self.acp_history.focus_handle(cx)
+                } else {
+                    self.history.focus_handle(cx)
+                }
+            }
+
             ActiveView::TextThread { context_editor, .. } => context_editor.focus_handle(cx),
             ActiveView::Configuration => {
                 if let Some(configuration) = self.configuration.as_ref() {
@@ -3517,7 +3554,13 @@ impl Render for AgentPanel {
                 ActiveView::ExternalAgentThread { thread_view, .. } => parent
                     .child(thread_view.clone())
                     .child(self.render_drag_target(cx)),
-                ActiveView::History => parent.child(self.history.clone()),
+                ActiveView::History => {
+                    if cx.has_flag::<feature_flags::AcpFeatureFlag>() {
+                        parent.child(self.acp_history.clone())
+                    } else {
+                        parent.child(self.history.clone())
+                    }
+                }
                 ActiveView::TextThread {
                     context_editor,
                     buffer_search_bar,