diff --git a/crates/acp_thread/src/acp_thread.rs b/crates/acp_thread/src/acp_thread.rs
index 2f3973fbcc94e2d06bdc08a91d61c53809a951ed..60054a0c52869889aa02ffebd8d7c8c5f46f553f 100644
--- a/crates/acp_thread/src/acp_thread.rs
+++ b/crates/acp_thread/src/acp_thread.rs
@@ -2162,17 +2162,13 @@ impl AcpThread {
         let request = acp::PromptRequest::new(self.session_id.clone(), message.clone());
         let git_store = self.project.read(cx).git_store().clone();
 
-        let message_id = if self.connection.truncate(&self.session_id, cx).is_some() {
-            Some(UserMessageId::new())
-        } else {
-            None
-        };
+        let message_id = UserMessageId::new();
 
         self.run_turn(cx, async move |this, cx| {
             this.update(cx, |this, cx| {
                 this.push_entry(
                     AgentThreadEntry::UserMessage(UserMessage {
-                        id: message_id.clone(),
+                        id: Some(message_id.clone()),
                         content: block,
                         chunks: message,
                         checkpoint: None,
@@ -4469,7 +4465,7 @@ mod tests {
 
         fn prompt(
             &self,
-            _id: Option<UserMessageId>,
+            _id: UserMessageId,
             params: acp::PromptRequest,
             cx: &mut App,
         ) -> Task<gpui::Result<acp::PromptResponse>> {
diff --git a/crates/acp_thread/src/connection.rs b/crates/acp_thread/src/connection.rs
index fbccdd1b93ae4cf5f632fe48abf3115562293a5c..58e66a7685d524a20a284cdc227df2c5b5b4e59b 100644
--- a/crates/acp_thread/src/connection.rs
+++ b/crates/acp_thread/src/connection.rs
@@ -125,7 +125,7 @@ pub trait AgentConnection {
 
     fn prompt(
         &self,
-        user_message_id: Option<UserMessageId>,
+        user_message_id: UserMessageId,
         params: acp::PromptRequest,
         cx: &mut App,
     ) -> Task<Result<acp::PromptResponse>>;
@@ -875,7 +875,7 @@ mod test_support {
 
         fn prompt(
             &self,
-            _id: Option<UserMessageId>,
+            _id: UserMessageId,
             params: acp::PromptRequest,
             cx: &mut App,
         ) -> Task<gpui::Result<acp::PromptResponse>> {
diff --git a/crates/agent/src/agent.rs b/crates/agent/src/agent.rs
index fe62d851ef1ba71c787aa6ec516b0b6b67449d67..33098cca24fb2a12ad78904b9adade884123209a 100644
--- a/crates/agent/src/agent.rs
+++ b/crates/agent/src/agent.rs
@@ -1489,11 +1489,10 @@ impl acp_thread::AgentConnection for NativeAgentConnection {
 
     fn prompt(
         &self,
-        id: Option<acp_thread::UserMessageId>,
+        id: acp_thread::UserMessageId,
         params: acp::PromptRequest,
         cx: &mut App,
     ) -> Task<Result<acp::PromptResponse>> {
-        let id = id.expect("UserMessageId is required");
         let session_id = params.session_id.clone();
         log::info!("Received prompt request for session: {}", session_id);
         log::debug!("Prompt blocks count: {}", params.prompt.len());
diff --git a/crates/agent/src/tests/mod.rs b/crates/agent/src/tests/mod.rs
index ff53136a0ded4bbc283fea30598d8d30e6e29709..2f4267b35616fafbf0a9b4cd2f4eecb2cfc1aec4 100644
--- a/crates/agent/src/tests/mod.rs
+++ b/crates/agent/src/tests/mod.rs
@@ -3350,7 +3350,7 @@ async fn test_agent_connection(cx: &mut TestAppContext) {
     let result = cx
         .update(|cx| {
             connection.prompt(
-                Some(acp_thread::UserMessageId::new()),
+                acp_thread::UserMessageId::new(),
                 acp::PromptRequest::new(session_id.clone(), vec!["ghi".into()]),
                 cx,
             )
diff --git a/crates/agent_servers/src/acp.rs b/crates/agent_servers/src/acp.rs
index dbcaabed1cf1971a6e281d8d31f8dad25dfb7434..54c24c91c89cde8faa4ab351aa8990b92b578050 100644
--- a/crates/agent_servers/src/acp.rs
+++ b/crates/agent_servers/src/acp.rs
@@ -955,7 +955,7 @@ impl AgentConnection for AcpConnection {
 
     fn prompt(
         &self,
-        _id: Option<acp_thread::UserMessageId>,
+        _id: acp_thread::UserMessageId,
         params: acp::PromptRequest,
         cx: &mut App,
     ) -> Task<Result<acp::PromptResponse>> {
diff --git a/crates/agent_ui/src/conversation_view.rs b/crates/agent_ui/src/conversation_view.rs
index 7a4b8b02e20c6b7757ad1e7048c9c739d339f734..ff5e6292f80c436dc9eec1e6883010604d6732dd 100644
--- a/crates/agent_ui/src/conversation_view.rs
+++ b/crates/agent_ui/src/conversation_view.rs
@@ -3252,7 +3252,7 @@ pub(crate) mod tests {
 
         fn prompt(
             &self,
-            _id: Option<acp_thread::UserMessageId>,
+            _id: acp_thread::UserMessageId,
             _params: acp::PromptRequest,
             _cx: &mut App,
         ) -> Task<gpui::Result<acp::PromptResponse>> {
@@ -4314,7 +4314,7 @@ pub(crate) mod tests {
 
         fn prompt(
             &self,
-            _id: Option<acp_thread::UserMessageId>,
+            _id: acp_thread::UserMessageId,
             _params: acp::PromptRequest,
             _cx: &mut App,
         ) -> Task<anyhow::Result<acp::PromptResponse>> {
@@ -4387,7 +4387,7 @@ pub(crate) mod tests {
 
         fn prompt(
             &self,
-            _id: Option<acp_thread::UserMessageId>,
+            _id: acp_thread::UserMessageId,
             _params: acp::PromptRequest,
             _cx: &mut App,
         ) -> Task<gpui::Result<acp::PromptResponse>> {
@@ -4486,7 +4486,7 @@ pub(crate) mod tests {
 
         fn prompt(
             &self,
-            _id: Option<acp_thread::UserMessageId>,
+            _id: acp_thread::UserMessageId,
             _params: acp::PromptRequest,
             _cx: &mut App,
         ) -> Task<gpui::Result<acp::PromptResponse>> {
@@ -4555,7 +4555,7 @@ pub(crate) mod tests {
 
         fn prompt(
             &self,
-            _id: Option<acp_thread::UserMessageId>,
+            _id: acp_thread::UserMessageId,
             _params: acp::PromptRequest,
             _cx: &mut App,
         ) -> Task<gpui::Result<acp::PromptResponse>> {
@@ -4625,7 +4625,7 @@ pub(crate) mod tests {
 
         fn prompt(
             &self,
-            _id: Option<acp_thread::UserMessageId>,
+            _id: acp_thread::UserMessageId,
             _params: acp::PromptRequest,
             _cx: &mut App,
         ) -> Task<gpui::Result<acp::PromptResponse>> {
@@ -4741,7 +4741,7 @@ pub(crate) mod tests {
 
         fn prompt(
             &self,
-            _id: Option<acp_thread::UserMessageId>,
+            _id: acp_thread::UserMessageId,
             _params: acp::PromptRequest,
             _cx: &mut App,
         ) -> Task<gpui::Result<acp::PromptResponse>> {
@@ -7343,7 +7343,7 @@ pub(crate) mod tests {
 
         fn prompt(
             &self,
-            _id: Option<acp_thread::UserMessageId>,
+            _id: acp_thread::UserMessageId,
             _params: acp::PromptRequest,
             _cx: &mut App,
         ) -> Task<gpui::Result<acp::PromptResponse>> {