From b277a654facca3dbfa5413bab68235f947f759ee Mon Sep 17 00:00:00 2001
From: Ahmed Ibrahim <aibrahim@openai.com>
Date: Fri, 22 Aug 2025 19:54:58 -0700
Subject: [PATCH] rust

---
 codex-rs/core/src/codex.rs |  3 ++-
 codex-rs/core/src/exec.rs  | 15 ++++++++++-----
 2 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/codex-rs/core/src/codex.rs b/codex-rs/core/src/codex.rs
index ea6ae8ce7c..c683978c37 100644
--- a/codex-rs/core/src/codex.rs
+++ b/codex-rs/core/src/codex.rs
@@ -142,6 +142,7 @@ pub struct CodexSpawnOk {
 }
 
 pub(crate) const INITIAL_SUBMIT_ID: &str = "";
+pub(crate) const SUBMISSION_CHANNEL_CAPACITY: usize = 64;
 
 // Model-formatting limits: clients get full streams; only formatted summary is capped.
 pub(crate) const MODEL_FORMAT_MAX_BYTES: usize = 10 * 1024; // 10 KiB
@@ -157,7 +158,7 @@ impl Codex {
         auth_manager: Arc<AuthManager>,
         initial_history: Option<Vec<ResponseItem>>,
     ) -> CodexResult<CodexSpawnOk> {
-        let (tx_sub, rx_sub) = async_channel::bounded(64);
+        let (tx_sub, rx_sub) = async_channel::bounded(SUBMISSION_CHANNEL_CAPACITY);
         let (tx_event, rx_event) = async_channel::unbounded();
 
         let user_instructions = get_user_instructions(&config).await;
diff --git a/codex-rs/core/src/exec.rs b/codex-rs/core/src/exec.rs
index e90e9061e2..d74ec9fcd3 100644
--- a/codex-rs/core/src/exec.rs
+++ b/codex-rs/core/src/exec.rs
@@ -34,6 +34,11 @@ const DEFAULT_TIMEOUT_MS: u64 = 10_000;
 // for these.
 const SIGKILL_CODE: i32 = 9;
 const TIMEOUT_CODE: i32 = 64;
+const EXIT_CODE_SIGNAL_BASE: i32 = 128; // conventional shell: 128 + signal
+
+// I/O buffer sizing
+const READ_CHUNK_SIZE: usize = 8192; // bytes per read
+const AGGREGATE_BUFFER_INITIAL_CAPACITY: usize = 8 * 1024; // 8 KiB
 
 #[derive(Debug, Clone)]
 pub struct ExecParams {
@@ -299,13 +304,13 @@ async fn consume_truncated_output(
                     // timeout
                     child.start_kill()?;
                     // Debatable whether `child.wait().await` should be called here.
-                    synthetic_exit_status(128 + TIMEOUT_CODE)
+                    synthetic_exit_status(EXIT_CODE_SIGNAL_BASE + TIMEOUT_CODE)
                 }
             }
         }
         _ = tokio::signal::ctrl_c() => {
             child.start_kill()?;
-            synthetic_exit_status(128 + SIGKILL_CODE)
+            synthetic_exit_status(EXIT_CODE_SIGNAL_BASE + SIGKILL_CODE)
         }
     };
 
@@ -314,7 +319,7 @@ async fn consume_truncated_output(
 
     drop(agg_tx);
 
-    let mut combined_buf = Vec::with_capacity(8 * 1024);
+    let mut combined_buf = Vec::with_capacity(AGGREGATE_BUFFER_INITIAL_CAPACITY);
     while let Ok(chunk) = agg_rx.recv().await {
         append_all(&mut combined_buf, &chunk);
     }
@@ -337,8 +342,8 @@ async fn read_capped<R: AsyncRead + Unpin + Send + 'static>(
     is_stderr: bool,
     aggregate_tx: Option<Sender<Vec<u8>>>,
 ) -> io::Result<StreamOutput<Vec<u8>>> {
-    let mut buf = Vec::with_capacity(8 * 1024);
-    let mut tmp = [0u8; 8192];
+    let mut buf = Vec::with_capacity(AGGREGATE_BUFFER_INITIAL_CAPACITY);
+    let mut tmp = [0u8; READ_CHUNK_SIZE];
 
     // No caps: append all bytes