tools: Send stale file notifications only once (#34026)

Previously, we sent notifications repeatedly until the agent read a
file, which was often inefficient. With this change, we now send a
notification only once (unless the files are modified again, in which
case we'll send another notification).

Release Notes:

- N/A

crates/assistant_tool/src/action_log.rs

@@ -1,5 +1,6 @@
 use anyhow::{Context as _, Result};
 use buffer_diff::BufferDiff;
+use clock;
 use collections::BTreeMap;
 use futures::{FutureExt, StreamExt, channel::mpsc};
 use gpui::{App, AppContext, AsyncApp, Context, Entity, Subscription, Task, WeakEntity};
@@ -17,6 +18,8 @@ pub struct ActionLog {
     edited_since_project_diagnostics_check: bool,
     /// The project this action log is associated with
     project: Entity<Project>,
+    /// Tracks which buffer versions have already been notified as changed externally
+    notified_versions: BTreeMap<Entity<Buffer>, clock::Global>,
 }
 
 impl ActionLog {
@@ -26,6 +29,7 @@ impl ActionLog {
             tracked_buffers: BTreeMap::default(),
             edited_since_project_diagnostics_check: false,
             project,
+            notified_versions: BTreeMap::default(),
         }
     }
 
@@ -51,6 +55,7 @@ impl ActionLog {
     ) -> &mut TrackedBuffer {
         let status = if is_created {
             if let Some(tracked) = self.tracked_buffers.remove(&buffer) {
+                self.notified_versions.remove(&buffer);
                 match tracked.status {
                     TrackedBufferStatus::Created {
                         existing_file_content,
@@ -106,7 +111,7 @@ impl ActionLog {
                 TrackedBuffer {
                     buffer: buffer.clone(),
                     diff_base,
-                    unreviewed_edits: unreviewed_edits,
+                    unreviewed_edits,
                     snapshot: text_snapshot.clone(),
                     status,
                     version: buffer.read(cx).version(),
@@ -165,6 +170,7 @@ impl ActionLog {
                     // If the buffer had been edited by a tool, but it got
                     // deleted externally, we want to stop tracking it.
                     self.tracked_buffers.remove(&buffer);
+                    self.notified_versions.remove(&buffer);
                 }
                 cx.notify();
             }
@@ -178,6 +184,7 @@ impl ActionLog {
                     // resurrected externally, we want to clear the edits we
                     // were tracking and reset the buffer's state.
                     self.tracked_buffers.remove(&buffer);
+                    self.notified_versions.remove(&buffer);
                     self.track_buffer_internal(buffer, false, cx);
                 }
                 cx.notify();
@@ -483,6 +490,7 @@ impl ActionLog {
         match tracked_buffer.status {
             TrackedBufferStatus::Created { .. } => {
                 self.tracked_buffers.remove(&buffer);
+                self.notified_versions.remove(&buffer);
                 cx.notify();
             }
             TrackedBufferStatus::Modified => {
@@ -508,6 +516,7 @@ impl ActionLog {
         match tracked_buffer.status {
             TrackedBufferStatus::Deleted => {
                 self.tracked_buffers.remove(&buffer);
+                self.notified_versions.remove(&buffer);
                 cx.notify();
             }
             _ => {
@@ -616,6 +625,7 @@ impl ActionLog {
                 };
 
                 self.tracked_buffers.remove(&buffer);
+                self.notified_versions.remove(&buffer);
                 cx.notify();
                 task
             }
@@ -629,6 +639,7 @@ impl ActionLog {
 
                 // Clear all tracked edits for this buffer and start over as if we just read it.
                 self.tracked_buffers.remove(&buffer);
+                self.notified_versions.remove(&buffer);
                 self.buffer_read(buffer.clone(), cx);
                 cx.notify();
                 save
@@ -713,6 +724,33 @@ impl ActionLog {
             .collect()
     }
 
+    /// Returns stale buffers that haven't been notified yet
+    pub fn unnotified_stale_buffers<'a>(
+        &'a self,
+        cx: &'a App,
+    ) -> impl Iterator<Item = &'a Entity<Buffer>> {
+        self.stale_buffers(cx).filter(|buffer| {
+            let buffer_entity = buffer.read(cx);
+            self.notified_versions
+                .get(buffer)
+                .map_or(true, |notified_version| {
+                    *notified_version != buffer_entity.version
+                })
+        })
+    }
+
+    /// Marks the given buffers as notified at their current versions
+    pub fn mark_buffers_as_notified(
+        &mut self,
+        buffers: impl IntoIterator<Item = Entity<Buffer>>,
+        cx: &App,
+    ) {
+        for buffer in buffers {
+            let version = buffer.read(cx).version.clone();
+            self.notified_versions.insert(buffer, version);
+        }
+    }
+
     /// Iterate over buffers changed since last read or edited by the model
     pub fn stale_buffers<'a>(&'a self, cx: &'a App) -> impl Iterator<Item = &'a Entity<Buffer>> {
         self.tracked_buffers