Enable edit prediction and Copilot for untitled buffers (#45764)

Closes [#45631](https://github.com/zed-industries/zed/issues/45631)

Recording:


https://github.com/user-attachments/assets/a5143eb4-fae3-42a7-9d64-fb7c42ee97c2


Release Notes:

- copilot: Edit predictions now work in temporary files

---------

Co-authored-by: Piotr Osiewicz <24362066+osiewicz@users.noreply.github.com>

crates/edit_prediction/src/edit_prediction.rs

@@ -725,7 +725,7 @@ fn compute_diff_between_snapshots_in_range(
     Some((diff, new_start_point..new_end_point))
 }
 
-fn buffer_path_with_id_fallback(
+pub(crate) fn buffer_path_with_id_fallback(
     file: Option<&Arc<dyn File>>,
     snapshot: &TextBufferSnapshot,
     cx: &App,

crates/edit_prediction/src/edit_prediction_tests.rs

@@ -3417,6 +3417,28 @@ async fn test_edit_prediction_settled(cx: &mut TestAppContext) {
     }
 }
 
+#[gpui::test]
+fn test_buffer_path_with_id_fallback_for_untitled_buffers(cx: &mut TestAppContext) {
+    let buffer_1 = cx.new(|cx| Buffer::local("one", cx));
+    let buffer_2 = cx.new(|cx| Buffer::local("two", cx));
+
+    let snapshot_1 = buffer_1.read_with(cx, |buffer, _| buffer.text_snapshot());
+    let snapshot_2 = buffer_2.read_with(cx, |buffer, _| buffer.text_snapshot());
+
+    let path_1 = cx.read(|cx| buffer_path_with_id_fallback(None, &snapshot_1, cx));
+    let path_2 = cx.read(|cx| buffer_path_with_id_fallback(None, &snapshot_2, cx));
+
+    assert_eq!(
+        path_1.as_ref(),
+        Path::new(&format!("untitled-{}", snapshot_1.remote_id()))
+    );
+    assert_eq!(
+        path_2.as_ref(),
+        Path::new(&format!("untitled-{}", snapshot_2.remote_id()))
+    );
+    assert_ne!(path_1.as_ref(), path_2.as_ref());
+}
+
 #[gpui::test]
 async fn test_data_collection_disabled_by_default(cx: &mut TestAppContext) {
     let (ep_store, _channels) = init_test_with_fake_client(cx);

crates/edit_prediction/src/zeta.rs

@@ -1,7 +1,7 @@
 use crate::{
     CurrentEditPrediction, DebugEvent, EditPredictionFinishedDebugEvent, EditPredictionId,
     EditPredictionModelInput, EditPredictionStartedDebugEvent, EditPredictionStore, StoredEvent,
-    ZedUpdateRequiredError,
+    ZedUpdateRequiredError, buffer_path_with_id_fallback,
     cursor_excerpt::{self, compute_cursor_excerpt, compute_syntax_ranges},
     prediction::EditPredictionResult,
 };
@@ -70,10 +70,7 @@ pub fn request_prediction_with_zeta(
     let preferred_experiment = store.preferred_experiment().map(|s| s.to_owned());
     let open_ai_compatible_api_key = load_open_ai_compatible_api_key_if_needed(provider, cx);
 
-    let excerpt_path: Arc<Path> = snapshot
-        .file()
-        .map(|file| -> Arc<Path> { file.full_path(cx).into() })
-        .unwrap_or_else(|| Arc::from(Path::new("untitled")));
+    let excerpt_path = buffer_path_with_id_fallback(snapshot.file(), &snapshot.text, cx);
 
     let repo_url = if can_collect_data {
         let buffer_id = buffer.read(cx).remote_id();

crates/zed/src/zed/edit_prediction_registry.rs

@@ -258,9 +258,7 @@ fn assign_edit_prediction_provider(
                 ep_store.update(cx, |this, cx| this.start_copilot_for_project(&project, cx));
 
             if let Some(copilot) = copilot {
-                if let Some(buffer) = singleton_buffer
-                    && buffer.read(cx).file().is_some()
-                {
+                if let Some(buffer) = singleton_buffer {
                     copilot.update(cx, |copilot, cx| {
                         copilot.register_buffer(&buffer, cx);
                     });