Fix stale edits (#42895)

Closes #34069

<img width="532" height="880" alt="Screenshot 2025-11-17 at 11 14 19 AM"
src="https://github.com/user-attachments/assets/abc50c32-d54d-4310-a6e6-83008db7ed81"
/>

<img width="525" height="863" alt="Screenshot 2025-11-17 at 12 22 50 PM"
src="https://github.com/user-attachments/assets/15a69792-c2c7-4727-add9-c1f9baa5e665"
/>

Release Notes:

- Agent file edits now error if the file has changed since last read
(allowing the agent to read changes and avoid overwriting changes made
outside Zed)

crates/remote_server/src/remote_editing_tests.rs

@@ -2,11 +2,12 @@
 /// The tests in this file assume that server_cx is running on Windows too.
 /// We neead to find a way to test Windows-Non-Windows interactions.
 use crate::headless_project::HeadlessProject;
-use agent::{AgentTool, ReadFileTool, ReadFileToolInput, ToolCallEventStream};
+use agent::{AgentTool, ReadFileTool, ReadFileToolInput, Templates, Thread, ToolCallEventStream};
 use client::{Client, UserStore};
 use clock::FakeSystemClock;
 use collections::{HashMap, HashSet};
-use language_model::LanguageModelToolResultContent;
+use language_model::{LanguageModelToolResultContent, fake_provider::FakeLanguageModel};
+use prompt_store::ProjectContext;
 
 use extension::ExtensionHostProxy;
 use fs::{FakeFs, Fs};
@@ -1722,12 +1723,27 @@ async fn test_remote_agent_fs_tool_calls(cx: &mut TestAppContext, server_cx: &mu
 
     let action_log = cx.new(|_| action_log::ActionLog::new(project.clone()));
 
+    // Create a minimal thread for the ReadFileTool
+    let context_server_registry =
+        cx.new(|cx| agent::ContextServerRegistry::new(project.read(cx).context_server_store(), cx));
+    let model = Arc::new(FakeLanguageModel::default());
+    let thread = cx.new(|cx| {
+        Thread::new(
+            project.clone(),
+            cx.new(|_cx| ProjectContext::default()),
+            context_server_registry,
+            Templates::new(),
+            Some(model),
+            cx,
+        )
+    });
+
     let input = ReadFileToolInput {
         path: "project/b.txt".into(),
         start_line: None,
         end_line: None,
     };
-    let read_tool = Arc::new(ReadFileTool::new(project, action_log));
+    let read_tool = Arc::new(ReadFileTool::new(thread.downgrade(), project, action_log));
     let (event_stream, _) = ToolCallEventStream::test();
 
     let exists_result = cx.update(|cx| read_tool.clone().run(input, event_stream.clone(), cx));