Remove app-server test RUST_MIN_STACK override

codex-rs/app-server/tests/common/mcp_process.rs

@@ -105,10 +105,6 @@ impl McpProcess {
         cmd.stderr(Stdio::piped());
         cmd.env("CODEX_HOME", codex_home);
         cmd.env("RUST_LOG", "debug");
-        // Bazel/Linux workers can run with smaller default thread stacks, which makes
-        // tokio-runtime-worker stack overflows more likely in app-server integration tests.
-        // Pin a larger minimum stack for the spawned test server process.
-        cmd.env("RUST_MIN_STACK", "4194304");
         cmd.env_remove(CODEX_INTERNAL_ORIGINATOR_OVERRIDE_ENV_VAR);
 
         for (k, v) in env_overrides {

codex-rs/arg0/src/lib.rs

@@ -13,7 +13,9 @@ const APPLY_PATCH_ARG0: &str = "apply_patch";
 const MISSPELLED_APPLY_PATCH_ARG0: &str = "applypatch";
 const LOCK_FILENAME: &str = ".lock";
 #[cfg(target_os = "windows")]
-const WINDOWS_TOKIO_WORKER_STACK_SIZE_BYTES: usize = 16 * 1024 * 1024;
+const TOKIO_WORKER_STACK_SIZE_BYTES: usize = 16 * 1024 * 1024;
+#[cfg(not(target_os = "windows"))]
+const TOKIO_WORKER_STACK_SIZE_BYTES: usize = 4 * 1024 * 1024;
 
 /// Keeps the per-session PATH entry alive and locked for the process lifetime.
 pub struct Arg0PathEntryGuard {
@@ -129,12 +131,10 @@ where
 fn build_runtime() -> anyhow::Result<tokio::runtime::Runtime> {
     let mut builder = tokio::runtime::Builder::new_multi_thread();
     builder.enable_all();
-    #[cfg(target_os = "windows")]
-    {
-        // Defensive hardening: Windows worker threads have lower effective
-        // stack headroom, so use a larger stack for runtime workers.
-        builder.thread_stack_size(WINDOWS_TOKIO_WORKER_STACK_SIZE_BYTES);
-    }
+    // Bazel/Linux workers commonly run with the default Tokio worker stack (2 MiB),
+    // which can overflow in deeper app-server startup paths (for example, detached review thread init).
+    // Pin a larger worker stack across platforms (Windows keeps the larger 16 MiB value).
+    builder.thread_stack_size(TOKIO_WORKER_STACK_SIZE_BYTES);
     Ok(builder.build()?)
 }