Emit an UpdateDiagnostics from Worktree when buffer diagnostics change

crates/project/src/worktree.rs

@@ -1097,15 +1097,43 @@ impl LocalWorktree {
                 buffer
             });
 
-            this.update(&mut cx, |this, _| {
+            this.update(&mut cx, |this, cx| {
                 let this = this.as_local_mut().unwrap();
                 this.open_buffers.insert(buffer.id(), buffer.downgrade());
+                cx.subscribe(&buffer, |worktree, buffer, event, cx| {
+                    worktree
+                        .as_local_mut()
+                        .unwrap()
+                        .on_buffer_event(buffer, event, cx);
+                })
+                .detach();
             });
 
             Ok(buffer)
         })
     }
 
+    fn on_buffer_event(
+        &mut self,
+        buffer: ModelHandle<Buffer>,
+        event: &language::Event,
+        cx: &mut ModelContext<Worktree>,
+    ) {
+        match event {
+            language::Event::DiagnosticsUpdated => {
+                let buffer = buffer.read(cx);
+                if let Some(path) = buffer.file().map(|file| file.path().clone()) {
+                    let diagnostics = buffer.all_diagnostics();
+                    self.diagnostic_summaries
+                        .insert(path.clone(), DiagnosticSummary::new(diagnostics));
+                    cx.emit(Event::DiagnosticsUpdated(path));
+                    cx.notify();
+                }
+            }
+            _ => {}
+        }
+    }
+
     pub fn open_remote_buffer(
         &mut self,
         envelope: TypedEnvelope<proto::OpenBuffer>,