code-mode: use compact session-local cell ids

codex-rs/core/src/tools/code_mode/execute_handler.rs

@@ -39,7 +39,7 @@ impl CodeModeExecuteHandler {
         let enabled_tools =
             codex_tools::collect_code_mode_tool_definitions(&self.nested_tool_specs);
         let started_at = std::time::Instant::now();
-        let cell_id = codex_code_mode::CellId::new(uuid::Uuid::new_v4().to_string());
+        let cell_id = exec.session.services.code_mode_service.allocate_cell_id();
         let runtime_cell_id = cell_id.to_string();
         let code_cell_trace = exec
             .session

codex-rs/core/src/tools/code_mode/mod.rs

@@ -6,6 +6,8 @@ mod wait_handler;
 pub(crate) mod wait_spec;
 
 use std::sync::Arc;
+use std::sync::atomic::AtomicU64;
+use std::sync::atomic::Ordering;
 use std::time::Duration;
 
 use codex_code_mode::CellId;
@@ -61,6 +63,7 @@ pub(crate) struct ExecContext {
 pub(crate) struct CodeModeService {
     session: Option<Arc<dyn CodeModeSession>>,
     dispatch_broker: Arc<CodeModeDispatchBroker>,
+    next_cell_id: AtomicU64,
 }
 
 impl CodeModeService {
@@ -71,9 +74,18 @@ impl CodeModeService {
                 dispatch_broker.clone(),
             ))),
             dispatch_broker,
+            next_cell_id: AtomicU64::new(1),
         }
     }
 
+    pub(crate) fn allocate_cell_id(&self) -> CellId {
+        CellId::new(
+            self.next_cell_id
+                .fetch_add(1, Ordering::Relaxed)
+                .to_string(),
+        )
+    }
+
     pub(crate) async fn execute(
         &self,
         request: codex_code_mode::ExecuteRequest,