diff --git a/codex-rs/core/src/tools/runtimes/unified_exec.rs b/codex-rs/core/src/tools/runtimes/unified_exec.rs
index 2050ec6969..fbf7c2a84b 100644
--- a/codex-rs/core/src/tools/runtimes/unified_exec.rs
+++ b/codex-rs/core/src/tools/runtimes/unified_exec.rs
@@ -280,7 +280,7 @@ impl<'a> ToolRuntime<UnifiedExecRequest, UnifiedExecProcess> for UnifiedExecRunt
         if let UnifiedExecShellMode::ZshFork(zsh_fork_config) = &self.shell_mode {
             let command =
                 build_sandbox_command(&command, &req.cwd, &env, req.additional_permissions.clone())
-                    .map_err(|_| ToolError::Rejected("missing command line for PTY".to_string()))?;
+                    .map_err(|_| ToolError::Codex(CodexErr::InvalidRequest("missing command line for PTY".into())))?;
             let options = unified_exec_options(attempt.network_denial_cancellation_token.clone());
             let mut exec_env = attempt
                 .env_for(command, options, managed_network)
@@ -319,7 +319,7 @@ impl<'a> ToolRuntime<UnifiedExecRequest, UnifiedExecProcess> for UnifiedExecRunt
                                     network_policy_decision: None,
                                 }))
                             }
-                            other => ToolError::Rejected(other.to_string()),
+                            other => ToolError::Codex(CodexErr::Fatal(other.to_string())),
                         });
                 }
                 None => {
@@ -331,7 +331,7 @@ impl<'a> ToolRuntime<UnifiedExecRequest, UnifiedExecProcess> for UnifiedExecRunt
         }
         let command =
             build_sandbox_command(&command, &req.cwd, &env, req.additional_permissions.clone())
-                .map_err(|_| ToolError::Rejected("missing command line for PTY".to_string()))?;
+                .map_err(|_| ToolError::Codex(CodexErr::InvalidRequest("missing command line for PTY".into())))?;
         let options = unified_exec_options(attempt.network_denial_cancellation_token.clone());
         let mut exec_env = attempt
             .env_for(command, options, managed_network)
@@ -353,7 +353,7 @@ impl<'a> ToolRuntime<UnifiedExecRequest, UnifiedExecProcess> for UnifiedExecRunt
                         network_policy_decision: None,
                     }))
                 }
-                other => ToolError::Rejected(other.to_string()),
+                other => ToolError::Codex(CodexErr::Fatal(other.to_string())),
             })
     }
 }
diff --git a/codex-rs/core/src/unified_exec/process_manager.rs b/codex-rs/core/src/unified_exec/process_manager.rs
index c1c927ab58..e77b1924d6 100644
--- a/codex-rs/core/src/unified_exec/process_manager.rs
+++ b/codex-rs/core/src/unified_exec/process_manager.rs
@@ -398,14 +398,13 @@ impl UnifiedExecProcessManager {
             }
             Err(err) => {
                 let failure = match &err {
-                    UnifiedExecError::MissingCommandLine => ToolEventFailure::Rejected {
-                        message: "missing command line for unified exec request".to_string(),
-                        applied_patch_delta: None,
-                    },
                     UnifiedExecError::Rejected { message } => ToolEventFailure::Rejected {
                         message: message.clone(),
                         applied_patch_delta: None,
                     },
+                    UnifiedExecError::SandboxDenied { output, .. } => {
+                        ToolEventFailure::Output(output.clone())
+                    }
                     _ => ToolEventFailure::Message(format!("execution error: {err:?}")),
                 };
                 emitter