assistant edit tool: Track read buffers and notify model of user edits (#26952)

When the model reads file, we'll track the version it read, and let it
know if the user makes edits to the buffer. This helps prevent edit
failures because it'll know to re-read the file before.

Release Notes:

- N/A

crates/assistant_tools/src/read_file_tool.rs

@@ -49,7 +49,7 @@ impl Tool for ReadFileTool {
         input: serde_json::Value,
         _messages: &[LanguageModelRequestMessage],
         project: Entity<Project>,
-        _action_log: Entity<ActionLog>,
+        action_log: Entity<ActionLog>,
         cx: &mut App,
     ) -> Task<Result<String>> {
         let input = match serde_json::from_value::<ReadFileToolInput>(input) {
@@ -60,14 +60,15 @@ impl Tool for ReadFileTool {
         let Some(project_path) = project.read(cx).find_project_path(&input.path, cx) else {
             return Task::ready(Err(anyhow!("Path not found in project")));
         };
-        cx.spawn(|cx| async move {
+
+        cx.spawn(|mut cx| async move {
             let buffer = cx
                 .update(|cx| {
                     project.update(cx, |project, cx| project.open_buffer(project_path, cx))
                 })?
                 .await?;
 
-            buffer.read_with(&cx, |buffer, _cx| {
+            let result = buffer.read_with(&cx, |buffer, _cx| {
                 if buffer
                     .file()
                     .map_or(false, |file| file.disk_state().exists())
@@ -76,7 +77,13 @@ impl Tool for ReadFileTool {
                 } else {
                     Err(anyhow!("File does not exist"))
                 }
-            })?
+            })??;
+
+            action_log.update(&mut cx, |log, cx| {
+                log.buffer_read(buffer, cx);
+            })?;
+
+            anyhow::Ok(result)
         })
     }
 }