tui: show aggregated output in display (#5539)

This shows the aggregated (stdout + stderr) buffer regardless of exit
code.

Many commands output useful / relevant info on stdout when returning a
non-zero exit code, or the same on stderr when returning an exit code of
0. Often, useful info is present on both stdout AND stderr. Also, the
model sees both. So it is confusing to see commands listed as "(no
output)" that in fact do have output, just on the stream that doesn't
match the exit status, or to see some sort of trivial output like "Tests
failed" but lacking any information about the actual failure.

As such, always display the aggregated output in the display. Transcript
mode remains unchanged as it was already displaying the text that the
model sees, which seems correct for transcript mode.

codex-rs/tui/src/exec_cell/model.rs

@@ -3,11 +3,12 @@ use std::time::Instant;
 
 use codex_protocol::parse_command::ParsedCommand;
 
-#[derive(Clone, Debug)]
+#[derive(Clone, Debug, Default)]
 pub(crate) struct CommandOutput {
     pub(crate) exit_code: i32,
-    pub(crate) stdout: String,
-    pub(crate) stderr: String,
+    /// The aggregated stderr + stdout interleaved.
+    pub(crate) aggregated_output: String,
+    /// The formatted output of the command, as seen by the model.
     pub(crate) formatted_output: String,
 }
 
@@ -82,9 +83,8 @@ impl ExecCell {
                 call.duration = Some(elapsed);
                 call.output = Some(CommandOutput {
                     exit_code: 1,
-                    stdout: String::new(),
-                    stderr: String::new(),
                     formatted_output: String::new(),
+                    aggregated_output: String::new(),
                 });
             }
         }

codex-rs/tui/src/exec_cell/render.rs

@@ -28,7 +28,6 @@ use unicode_width::UnicodeWidthStr;
 pub(crate) const TOOL_CALL_MAX_LINES: usize = 5;
 
 pub(crate) struct OutputLinesParams {
-    pub(crate) only_err: bool,
     pub(crate) include_angle_pipe: bool,
     pub(crate) include_prefix: bool,
 }
@@ -59,22 +58,12 @@ pub(crate) fn output_lines(
     params: OutputLinesParams,
 ) -> OutputLines {
     let OutputLinesParams {
-        only_err,
         include_angle_pipe,
         include_prefix,
     } = params;
     let CommandOutput {
-        exit_code,
-        stdout,
-        stderr,
-        ..
+        aggregated_output, ..
     } = match output {
-        Some(output) if only_err && output.exit_code == 0 => {
-            return OutputLines {
-                lines: Vec::new(),
-                omitted: None,
-            };
-        }
         Some(output) => output,
         None => {
             return OutputLines {
@@ -84,7 +73,7 @@ pub(crate) fn output_lines(
         }
     };
 
-    let src = if *exit_code == 0 { stdout } else { stderr };
+    let src = aggregated_output;
     let lines: Vec<&str> = src.lines().collect();
     let total = lines.len();
     let limit = TOOL_CALL_MAX_LINES;
@@ -398,7 +387,6 @@ impl ExecCell {
             let raw_output = output_lines(
                 Some(output),
                 OutputLinesParams {
-                    only_err: false,
                     include_angle_pipe: false,
                     include_prefix: false,
                 },