agent_ui: Fix project path not found error when pasting code from other project (#44555)

The problem with inserting the absolute paths is that the agent will try
to read them. However, we don't allow the agent to read files outside
the current project. For now, we will only insert the crease in case the
code that is getting pasted is from the same project

Release Notes:

- Fixed an issue where pasting code into the agent panel from another
window would show an error

crates/agent_ui/src/acp/message_editor.rs

@@ -565,8 +565,26 @@ impl MessageEditor {
             if let Some((workspace, selections)) =
                 self.workspace.upgrade().zip(editor_clipboard_selections)
             {
-                cx.stop_propagation();
+                let Some(first_selection) = selections.first() else {
+                    return;
+                };
+                if let Some(file_path) = &first_selection.file_path {
+                    // In case someone pastes selections from another window
+                    // with a different project, we don't want to insert the
+                    // crease (containing the absolute path) since the agent
+                    // cannot access files outside the project.
+                    let is_in_project = workspace
+                        .read(cx)
+                        .project()
+                        .read(cx)
+                        .project_path_for_absolute_path(file_path, cx)
+                        .is_some();
+                    if !is_in_project {
+                        return;
+                    }
+                }
 
+                cx.stop_propagation();
                 let insertion_target = self
                     .editor
                     .read(cx)