fix: apply_patch shell_serialization tests (#4786)

## Summary
Adds additional shell_serialization tests specifically for apply_patch
and other cases.

## Test Plan
- [x] These are all tests

codex-rs/core/src/executor/backends.rs

@@ -6,6 +6,7 @@ use async_trait::async_trait;
 use crate::CODEX_APPLY_PATCH_ARG1;
 use crate::apply_patch::ApplyPatchExec;
 use crate::exec::ExecParams;
+use crate::executor::ExecutorConfig;
 use crate::function_tool::FunctionCallError;
 
 pub(crate) enum ExecutionMode {
@@ -22,6 +23,7 @@ pub(crate) trait ExecutionBackend: Send + Sync {
         params: ExecParams,
         // Required for downcasting the apply_patch.
         mode: &ExecutionMode,
+        config: &ExecutorConfig,
     ) -> Result<ExecParams, FunctionCallError>;
 
     fn stream_stdout(&self, _mode: &ExecutionMode) -> bool {
@@ -47,6 +49,7 @@ impl ExecutionBackend for ShellBackend {
         &self,
         params: ExecParams,
         mode: &ExecutionMode,
+        _config: &ExecutorConfig,
     ) -> Result<ExecParams, FunctionCallError> {
         match mode {
             ExecutionMode::Shell => Ok(params),
@@ -65,17 +68,22 @@ impl ExecutionBackend for ApplyPatchBackend {
         &self,
         params: ExecParams,
         mode: &ExecutionMode,
+        config: &ExecutorConfig,
     ) -> Result<ExecParams, FunctionCallError> {
         match mode {
             ExecutionMode::ApplyPatch(exec) => {
-                let path_to_codex = env::current_exe()
-                    .ok()
-                    .map(|p| p.to_string_lossy().to_string())
-                    .ok_or_else(|| {
-                        FunctionCallError::RespondToModel(
-                            "failed to determine path to codex executable".to_string(),
-                        )
-                    })?;
+                let path_to_codex = if let Some(exe_path) = &config.codex_exe {
+                    exe_path.to_string_lossy().to_string()
+                } else {
+                    env::current_exe()
+                        .ok()
+                        .map(|p| p.to_string_lossy().to_string())
+                        .ok_or_else(|| {
+                            FunctionCallError::RespondToModel(
+                                "failed to determine path to codex executable".to_string(),
+                            )
+                        })?
+                };
 
                 let patch = exec.action.patch.clone();
                 Ok(ExecParams {

codex-rs/core/src/executor/runner.rs

@@ -30,19 +30,19 @@ use codex_otel::otel_event_manager::ToolDecisionSource;
 pub(crate) struct ExecutorConfig {
     pub(crate) sandbox_policy: SandboxPolicy,
     pub(crate) sandbox_cwd: PathBuf,
-    codex_linux_sandbox_exe: Option<PathBuf>,
+    pub(crate) codex_exe: Option<PathBuf>,
 }
 
 impl ExecutorConfig {
     pub(crate) fn new(
         sandbox_policy: SandboxPolicy,
         sandbox_cwd: PathBuf,
-        codex_linux_sandbox_exe: Option<PathBuf>,
+        codex_exe: Option<PathBuf>,
     ) -> Self {
         Self {
             sandbox_policy,
             sandbox_cwd,
-            codex_linux_sandbox_exe,
+            codex_exe,
         }
     }
 }
@@ -86,7 +86,14 @@ impl Executor {
                 maybe_translate_shell_command(request.params, session, request.use_shell_profile);
         }
 
-        // Step 1: Normalise parameters via the selected backend.
+        // Step 1: Snapshot sandbox configuration so it stays stable for this run.
+        let config = self
+            .config
+            .read()
+            .map_err(|_| ExecError::rejection("executor config poisoned"))?
+            .clone();
+
+        // Step 2: Normalise parameters via the selected backend.
         let backend = backend_for_mode(&request.mode);
         let stdout_stream = if backend.stream_stdout(&request.mode) {
             request.stdout_stream.clone()
@@ -94,16 +101,9 @@ impl Executor {
             None
         };
         request.params = backend
-            .prepare(request.params, &request.mode)
+            .prepare(request.params, &request.mode, &config)
             .map_err(ExecError::from)?;
 
-        // Step 2: Snapshot sandbox configuration so it stays stable for this run.
-        let config = self
-            .config
-            .read()
-            .map_err(|_| ExecError::rejection("executor config poisoned"))?
-            .clone();
-
         // Step 3: Decide sandbox placement, prompting for approval when needed.
         let sandbox_decision = select_sandbox(
             &request,
@@ -227,7 +227,7 @@ impl Executor {
             sandbox,
             &config.sandbox_policy,
             &config.sandbox_cwd,
-            &config.codex_linux_sandbox_exe,
+            &config.codex_exe,
             stdout_stream,
         )
         .await