agent: Fix elicitation tool-call IDs (#64086)

Use the native tool call's scoped ID for elicitation requests instead of
constructing an ID from the raw provider-issued tool-use ID. This keeps
`ask_user` forms associated with the correct conversation entry,
including when providers reuse raw IDs.

Release Notes:

- N/A

crates/agent/src/thread.rs

@@ -6365,14 +6365,14 @@ impl ToolCallEventStream {
         cx: &mut App,
     ) -> Task<Result<acp::CreateElicitationResponse>> {
         let stream = self.stream.clone();
-        let tool_use_id = self.tool_use_id.clone();
+        let tool_call_id = self.tool_call_id.clone();
         cx.spawn(async move |_cx| {
             let (response_tx, response_rx) = oneshot::channel();
             if let Err(error) =
                 stream
                     .0
                     .unbounded_send(Ok(ThreadEvent::Elicitation(ElicitationRequest {
-                        tool_call_id: acp::ToolCallId::new(tool_use_id.to_string()),
+                        tool_call_id,
                         message,
                         schema,
                         response: response_tx,

crates/agent/src/tools/ask_user_tool.rs

@@ -234,6 +234,7 @@ mod tests {
     #[gpui::test]
     async fn test_ask_user_returns_selected_option(cx: &mut TestAppContext) {
         let (event_stream, mut event_rx) = ToolCallEventStream::test();
+        let tool_call_id = event_stream.tool_call_id().clone();
         let tool = Arc::new(AskUserTool);
         let task = cx.update(|cx| {
             tool.run(
@@ -248,6 +249,7 @@ mod tests {
         });
 
         let request = event_rx.expect_elicitation().await;
+        assert_eq!(request.tool_call_id, tool_call_id);
         assert_eq!(request.message, "Which approach?");
         assert!(request.schema.properties.contains_key(CHOICE_FIELD));
         assert!(!request.schema.properties.contains_key(OTHER_FIELD));