diff --git a/codex-rs/app-server/tests/common/responses.rs b/codex-rs/app-server/tests/common/responses.rs
index d3d1f40cdc..514df8b044 100644
--- a/codex-rs/app-server/tests/common/responses.rs
+++ b/codex-rs/app-server/tests/common/responses.rs
@@ -96,16 +96,21 @@ pub fn create_apply_patch_sse_response(
 }
 
 pub fn create_exec_command_sse_response(call_id: &str) -> anyhow::Result<String> {
-    let (cmd, args) = if cfg!(windows) {
-        ("cmd.exe", vec!["/d", "/c", "echo hi"])
+    let cmd = if cfg!(windows) {
+        // Keep this as a plain string: our exec tool ultimately runs the string
+        // via a shell anyway, and joining args naively loses quoting.
+        "cmd.exe /d /c echo hi".to_string()
     } else {
-        ("/bin/sh", vec!["-c", "echo hi"])
+        // Keep the command simple and shell-native so it's stable under Buck2's
+        // sandboxing / symlink trees.
+        "echo hi".to_string()
     };
-    let command = std::iter::once(cmd.to_string())
-        .chain(args.into_iter().map(str::to_string))
-        .collect::<Vec<_>>();
     let tool_call_arguments = serde_json::to_string(&json!({
-        "cmd": command.join(" "),
+        "cmd": cmd,
+        // Force a non-login shell for determinism: under Buck2 test runners,
+        // login shells can pick up environment/profile differences that make
+        // this simple command flaky.
+        "login": false,
         "yield_time_ms": 500
     }))?;
     let tool_call = json!({
diff --git a/codex-rs/apply-patch/tests/suite/scenarios.rs b/codex-rs/apply-patch/tests/suite/scenarios.rs
index b35ed8590d..0e21a7bc0a 100644
--- a/codex-rs/apply-patch/tests/suite/scenarios.rs
+++ b/codex-rs/apply-patch/tests/suite/scenarios.rs
@@ -8,7 +8,8 @@ use tempfile::tempdir;
 
 #[test]
 fn test_apply_patch_scenarios() -> anyhow::Result<()> {
-    for scenario in fs::read_dir("tests/fixtures/scenarios")? {
+    let scenarios_dir = Path::new(env!("CARGO_MANIFEST_DIR")).join("tests/fixtures/scenarios");
+    for scenario in fs::read_dir(scenarios_dir)? {
         let scenario = scenario?;
         let path = scenario.path();
         if path.is_dir() {
@@ -81,11 +82,15 @@ fn snapshot_dir_recursive(
             continue;
         };
         let rel = stripped.to_path_buf();
-        let file_type = entry.file_type()?;
-        if file_type.is_dir() {
+
+        // Under Buck2, files in `__srcs` are often materialized as symlinks.
+        // Use `metadata()` (follows symlinks) so our fixture snapshots work
+        // under both Cargo and Buck2.
+        let metadata = fs::metadata(&path)?;
+        if metadata.is_dir() {
             entries.insert(rel.clone(), Entry::Dir);
             snapshot_dir_recursive(base, &path, entries)?;
-        } else if file_type.is_file() {
+        } else if metadata.is_file() {
             let contents = fs::read(&path)?;
             entries.insert(rel, Entry::File(contents));
         }
@@ -97,12 +102,14 @@ fn copy_dir_recursive(src: &Path, dst: &Path) -> anyhow::Result<()> {
     for entry in fs::read_dir(src)? {
         let entry = entry?;
         let path = entry.path();
-        let file_type = entry.file_type()?;
         let dest_path = dst.join(entry.file_name());
-        if file_type.is_dir() {
+
+        // See note in `snapshot_dir_recursive` about Buck2 symlink trees.
+        let metadata = fs::metadata(&path)?;
+        if metadata.is_dir() {
             fs::create_dir_all(&dest_path)?;
             copy_dir_recursive(&path, &dest_path)?;
-        } else if file_type.is_file() {
+        } else if metadata.is_file() {
             if let Some(parent) = dest_path.parent() {
                 fs::create_dir_all(parent)?;
             }