[codex] test exec relative additional permissions (#28587)

## Why

Review caught some would-be regressions in changes to unified_exec that
weren't surfaced in CI.

## What

Add coverage for requesting permissions through unified exec when there
are additional permissions. Previously this flow was only tested against
shell_command.

codex-rs/core/tests/suite/request_permissions.rs

@@ -41,6 +41,7 @@ use serde_json::Value;
 use serde_json::json;
 use std::fs;
 use std::path::Path;
+use test_case::test_case;
 
 fn absolute_path(path: &Path) -> AbsolutePathBuf {
     AbsolutePathBuf::try_from(path).expect("absolute path")
@@ -164,23 +165,6 @@ fn exec_command_event_with_missing_additional_permissions(
     Ok(ev_function_call(call_id, "exec_command", &args_str))
 }
 
-fn shell_event_with_raw_request_permissions(
-    call_id: &str,
-    command: &str,
-    workdir: Option<&str>,
-    additional_permissions: Value,
-) -> Result<Value> {
-    let args = json!({
-        "command": command,
-        "workdir": workdir,
-        "timeout_ms": 1_000_u64,
-        "sandbox_permissions": SandboxPermissions::WithAdditionalPermissions,
-        "additional_permissions": additional_permissions,
-    });
-    let args_str = serde_json::to_string(&args)?;
-    Ok(ev_function_call(call_id, "shell_command", &args_str))
-}
-
 async fn submit_turn(
     test: &TestCodex,
     prompt: &str,
@@ -507,8 +491,18 @@ async fn request_permissions_tool_is_auto_denied_when_granular_request_permissio
     Ok(())
 }
 
+#[derive(Clone, Copy, Debug)]
+enum AdditionalPermissionsCommandTool {
+    ShellCommand,
+    ExecCommand,
+}
+
+#[test_case(AdditionalPermissionsCommandTool::ShellCommand ; "shell_command")]
+#[test_case(AdditionalPermissionsCommandTool::ExecCommand ; "exec_command")]
 #[tokio::test(flavor = "current_thread")]
-async fn relative_additional_permissions_resolve_against_tool_workdir() -> Result<()> {
+async fn relative_additional_permissions_resolve_against_tool_workdir(
+    command_tool: AdditionalPermissionsCommandTool,
+) -> Result<()> {
     skip_if_no_network!(Ok(()));
     skip_if_sandbox!(Ok(()));
 
@@ -542,6 +536,12 @@ async fn relative_additional_permissions_resolve_against_tool_workdir() -> Resul
 
     let call_id = "request_permissions_relative_workdir";
     let command = "touch relative-write.txt";
+    let workdir = "nested";
+    let additional_permissions = json!({
+        "file_system": {
+            "write": ["."],
+        },
+    });
     let expected_permissions = PermissionProfile {
         file_system: Some(FileSystemPermissions::from_read_write_roots(
             /*read*/ None,
@@ -549,16 +549,27 @@ async fn relative_additional_permissions_resolve_against_tool_workdir() -> Resul
         )),
         ..Default::default()
     };
-    let event = shell_event_with_raw_request_permissions(
-        call_id,
-        command,
-        Some("nested"),
-        json!({
-            "file_system": {
-                "write": ["."],
-            },
-        }),
-    )?;
+    let (tool_name, arguments) = match command_tool {
+        AdditionalPermissionsCommandTool::ShellCommand => (
+            "shell_command",
+            json!({
+                "command": command,
+                "workdir": workdir,
+                "sandbox_permissions": SandboxPermissions::WithAdditionalPermissions,
+                "additional_permissions": additional_permissions,
+            }),
+        ),
+        AdditionalPermissionsCommandTool::ExecCommand => (
+            "exec_command",
+            json!({
+                "cmd": command,
+                "workdir": workdir,
+                "sandbox_permissions": SandboxPermissions::WithAdditionalPermissions,
+                "additional_permissions": additional_permissions,
+            }),
+        ),
+    };
+    let event = ev_function_call(call_id, tool_name, &serde_json::to_string(&arguments)?);
 
     let _ = mount_sse_once(
         &server,