Run exec-server fs operations through sandbox helper (#17294)

## Summary
- run exec-server filesystem RPCs requiring sandboxing through a
`codex-fs` arg0 helper over stdin/stdout
- keep direct local filesystem execution for `DangerFullAccess` and
external sandbox policies
- remove the standalone exec-server binary path in favor of top-level
arg0 dispatch/runtime paths
- add sandbox escape regression coverage for local and remote filesystem
paths

## Validation
- `just fmt`
- `git diff --check`
- remote devbox: `cd codex-rs && bazel test --bes_backend=
--bes_results_url= //codex-rs/exec-server:all` (6/6 passed)

---------

Co-authored-by: Codex <noreply@openai.com>

scripts/run_tui_with_exec_server.sh

@@ -24,7 +24,7 @@ trap cleanup EXIT INT TERM HUP
 
 (
   cd "$cargo_root"
-  cargo run -p codex-exec-server -- --listen "$listen_url"
+  cargo run -p codex-cli --bin codex -- exec-server --listen "$listen_url"
 ) >"$stdout_log" 2>"$stderr_log" &
 server_pid="$!"
 
@@ -40,7 +40,7 @@ for _ in $(seq 1 "$((start_timeout_seconds * 20))"); do
   if ! kill -0 "$server_pid" >/dev/null 2>&1; then
     cat "$stderr_log" >&2 || true
     cat "$stdout_log" >&2 || true
-    echo "failed to start codex-exec-server" >&2
+    echo "failed to start codex exec-server" >&2
     exit 1
   fi
 
@@ -50,7 +50,7 @@ done
 if [[ -z "$exec_server_url" ]]; then
   cat "$stderr_log" >&2 || true
   cat "$stdout_log" >&2 || true
-  echo "timed out waiting ${start_timeout_seconds}s for codex-exec-server to report its websocket URL" >&2
+  echo "timed out waiting ${start_timeout_seconds}s for codex exec-server to report its websocket URL" >&2
   exit 1
 fi
 

scripts/start-codex-exec.sh

@@ -105,10 +105,10 @@ remote_repo_root="$HOME/code/codex-sync"
 remote_codex_rs="$remote_repo_root/codex-rs"
 
 cd "${remote_codex_rs}"
-cargo build -p codex-exec-server --bin codex-exec-server
+cargo build -p codex-cli --bin codex
 
 rm -f "${remote_exec_server_log_path}" "${remote_exec_server_pid_path}"
-nohup ./target/debug/codex-exec-server --listen ws://127.0.0.1:0 \
+nohup ./target/debug/codex exec-server --listen ws://127.0.0.1:0 \
   >"${remote_exec_server_log_path}" 2>&1 &
 remote_exec_server_pid="$!"
 echo "${remote_exec_server_pid}" >"${remote_exec_server_pid_path}"

scripts/test-remote-env.sh

@@ -17,10 +17,10 @@ is_sourced() {
 
 setup_remote_env() {
   local container_name
-  local codex_exec_server_binary_path
+  local codex_binary_path
 
   container_name="${CODEX_TEST_REMOTE_ENV_CONTAINER_NAME:-codex-remote-test-env-local-$(date +%s)-${RANDOM}}"
-  codex_exec_server_binary_path="${REPO_ROOT}/codex-rs/target/debug/codex-exec-server"
+  codex_binary_path="${REPO_ROOT}/codex-rs/target/debug/codex"
 
   if ! command -v docker >/dev/null 2>&1; then
     echo "docker is required (Colima or Docker Desktop)" >&2
@@ -33,17 +33,17 @@ setup_remote_env() {
   fi
 
   if ! command -v cargo >/dev/null 2>&1; then
-    echo "cargo is required to build codex-exec-server" >&2
+    echo "cargo is required to build codex" >&2
     return 1
   fi
 
   (
     cd "${REPO_ROOT}/codex-rs"
-    cargo build -p codex-exec-server --bin codex-exec-server
+    cargo build -p codex-cli --bin codex
   )
 
-  if [[ ! -f "${codex_exec_server_binary_path}" ]]; then
-    echo "codex-exec-server binary not found at ${codex_exec_server_binary_path}" >&2
+  if [[ ! -f "${codex_binary_path}" ]]; then
+    echo "codex binary not found at ${codex_binary_path}" >&2
     return 1
   fi