assistant edit tool: Fix editing files in context (#26751)

When the user attached context in the thread, the editor model request
would fail because its tool use wouldn't be removed properly leading to
an API error.

Also, after an edit, we'd keep the old file snapshot in the context.
This would make the model think that the edits didn't apply and make it
go in a loop.

Release Notes:

- N/A

crates/assistant_tool/src/assistant_tool.rs

@@ -4,7 +4,10 @@ mod tool_working_set;
 use std::sync::Arc;
 
 use anyhow::Result;
+use collections::HashSet;
+use gpui::Context;
 use gpui::{App, Entity, SharedString, Task};
+use language::Buffer;
 use language_model::LanguageModelRequestMessage;
 use project::Project;
 
@@ -47,6 +50,39 @@ pub trait Tool: 'static + Send + Sync {
         input: serde_json::Value,
         messages: &[LanguageModelRequestMessage],
         project: Entity<Project>,
+        action_log: Entity<ActionLog>,
         cx: &mut App,
     ) -> Task<Result<String>>;
 }
+
+/// Tracks actions performed by tools in a thread
+#[derive(Debug)]
+pub struct ActionLog {
+    changed_buffers: HashSet<Entity<Buffer>>,
+    pending_refresh: HashSet<Entity<Buffer>>,
+}
+
+impl ActionLog {
+    /// Creates a new, empty action log.
+    pub fn new() -> Self {
+        Self {
+            changed_buffers: HashSet::default(),
+            pending_refresh: HashSet::default(),
+        }
+    }
+
+    /// Registers buffers that have changed and need refreshing.
+    pub fn notify_buffers_changed(
+        &mut self,
+        buffers: HashSet<Entity<Buffer>>,
+        _cx: &mut Context<Self>,
+    ) {
+        self.changed_buffers.extend(buffers.clone());
+        self.pending_refresh.extend(buffers);
+    }
+
+    /// Takes and returns the set of buffers pending refresh, clearing internal state.
+    pub fn take_pending_refresh_buffers(&mut self) -> HashSet<Entity<Buffer>> {
+        std::mem::take(&mut self.pending_refresh)
+    }
+}