Remove ACP feature flags (#38055)

This removes the `gemini-and-native` and `claude-code` feature flags.
Also, I removed a bunch of unused agent1 code that we do not need
anymore.

Initially I wanted to remove much more of the `agent` code, but noticed
some things that we need to figure out first:
- The inline assistant + context strip use `Thread`/`ContextStore`
directly
- We need some replacement for `ToolWorkingSet`, so we can access
available tools (as well as context server tools) in other places, e.g.
the agent configuration and the configure profile modal

Release Notes:

- N/A

crates/agent/src/history_store.rs

@@ -1,7 +1,4 @@
-use crate::{
-    ThreadId,
-    thread_store::{SerializedThreadMetadata, ThreadStore},
-};
+use crate::{ThreadId, thread_store::SerializedThreadMetadata};
 use anyhow::{Context as _, Result};
 use assistant_context::SavedContextMetadata;
 use chrono::{DateTime, Utc};
@@ -61,7 +58,6 @@ enum SerializedRecentOpen {
 }
 
 pub struct HistoryStore {
-    thread_store: Entity<ThreadStore>,
     context_store: Entity<assistant_context::ContextStore>,
     recently_opened_entries: VecDeque<HistoryEntryId>,
     _subscriptions: Vec<gpui::Subscription>,
@@ -70,15 +66,11 @@ pub struct HistoryStore {
 
 impl HistoryStore {
     pub fn new(
-        thread_store: Entity<ThreadStore>,
         context_store: Entity<assistant_context::ContextStore>,
         initial_recent_entries: impl IntoIterator<Item = HistoryEntryId>,
         cx: &mut Context<Self>,
     ) -> Self {
-        let subscriptions = vec![
-            cx.observe(&thread_store, |_, _, cx| cx.notify()),
-            cx.observe(&context_store, |_, _, cx| cx.notify()),
-        ];
+        let subscriptions = vec![cx.observe(&context_store, |_, _, cx| cx.notify())];
 
         cx.spawn(async move |this, cx| {
             let entries = Self::load_recently_opened_entries(cx).await.log_err()?;
@@ -96,7 +88,6 @@ impl HistoryStore {
         .detach();
 
         Self {
-            thread_store,
             context_store,
             recently_opened_entries: initial_recent_entries.into_iter().collect(),
             _subscriptions: subscriptions,
@@ -112,13 +103,6 @@ impl HistoryStore {
             return history_entries;
         }
 
-        history_entries.extend(
-            self.thread_store
-                .read(cx)
-                .reverse_chronological_threads()
-                .cloned()
-                .map(HistoryEntry::Thread),
-        );
         history_entries.extend(
             self.context_store
                 .read(cx)
@@ -141,22 +125,6 @@ impl HistoryStore {
             return Vec::new();
         }
 
-        let thread_entries = self
-            .thread_store
-            .read(cx)
-            .reverse_chronological_threads()
-            .flat_map(|thread| {
-                self.recently_opened_entries
-                    .iter()
-                    .enumerate()
-                    .flat_map(|(index, entry)| match entry {
-                        HistoryEntryId::Thread(id) if &thread.id == id => {
-                            Some((index, HistoryEntry::Thread(thread.clone())))
-                        }
-                        _ => None,
-                    })
-            });
-
         let context_entries =
             self.context_store
                 .read(cx)
@@ -173,8 +141,7 @@ impl HistoryStore {
                         })
                 });
 
-        thread_entries
-            .chain(context_entries)
+        context_entries
             // optimization to halt iteration early
             .take(self.recently_opened_entries.len())
             .sorted_unstable_by_key(|(index, _)| *index)