Refactor exec-server filesystem API into codex-file-system (#19892)

## Summary
- Extracted the shared filesystem types and `ExecutorFileSystem` trait
into a new `codex-file-system` crate
- Switched `codex-config` and `codex-git-utils` to depend on that crate
instead of `codex-exec-server`
- Kept `codex-exec-server` re-exporting the same API for existing
callers

## Testing
- Ran `cargo test -p codex-file-system`
- Ran `cargo test -p codex-git-utils`
- Ran `cargo test -p codex-config`
- Ran `cargo test -p codex-exec-server`
- Ran `just fix -p codex-file-system`, `just fix -p codex-git-utils`,
`just fix -p codex-config`, `just fix -p codex-exec-server`
- Ran `just fmt`
- Updated and verified the Bazel module lockfile

codex-rs/Cargo.lock

@@ -2288,9 +2288,9 @@ dependencies = [
  "async-trait",
  "base64 0.22.1",
  "codex-app-server-protocol",
- "codex-exec-server",
  "codex-execpolicy",
  "codex-features",
+ "codex-file-system",
  "codex-git-utils",
  "codex-model-provider-info",
  "codex-network-proxy",
@@ -2609,6 +2609,7 @@ dependencies = [
  "bytes",
  "codex-app-server-protocol",
  "codex-client",
+ "codex-file-system",
  "codex-protocol",
  "codex-sandboxing",
  "codex-test-binary-support",
@@ -2719,6 +2720,16 @@ dependencies = [
  "tokio",
 ]
 
+[[package]]
+name = "codex-file-system"
+version = "0.0.0"
+dependencies = [
+ "async-trait",
+ "codex-protocol",
+ "codex-utils-absolute-path",
+ "serde",
+]
+
 [[package]]
 name = "codex-git-utils"
 version = "0.0.0"
@@ -2726,7 +2737,7 @@ dependencies = [
  "anyhow",
  "assert_matches",
  "chrono",
- "codex-exec-server",
+ "codex-file-system",
  "codex-protocol",
  "codex-utils-absolute-path",
  "futures",

codex-rs/Cargo.toml

@@ -36,6 +36,7 @@ members = [
     "hooks",
     "secrets",
     "exec",
+    "file-system",
     "exec-server",
     "execpolicy",
     "execpolicy-legacy",
@@ -142,6 +143,7 @@ codex-core-plugins = { path = "core-plugins" }
 codex-core-skills = { path = "core-skills" }
 codex-device-key = { path = "device-key" }
 codex-exec = { path = "exec" }
+codex-file-system = { path = "file-system" }
 codex-exec-server = { path = "exec-server" }
 codex-execpolicy = { path = "execpolicy" }
 codex-experimental-api-macros = { path = "codex-experimental-api-macros" }

codex-rs/config/Cargo.toml

@@ -16,9 +16,9 @@ anyhow = { workspace = true }
 async-trait = { workspace = true }
 base64 = { workspace = true }
 codex-app-server-protocol = { workspace = true }
-codex-exec-server = { workspace = true }
 codex-execpolicy = { workspace = true }
 codex-features = { workspace = true }
+codex-file-system = { workspace = true }
 codex-git-utils = { workspace = true }
 codex-model-provider-info = { workspace = true }
 codex-network-proxy = { workspace = true }

codex-rs/config/src/loader/layer_io.rs

@@ -5,7 +5,7 @@ use super::macos::load_managed_admin_config_layer;
 use crate::diagnostics::config_error_from_toml;
 use crate::diagnostics::io_error_from_config_error;
 use crate::state::LoaderOverrides;
-use codex_exec_server::ExecutorFileSystem;
+use codex_file_system::ExecutorFileSystem;
 use codex_utils_absolute_path::AbsolutePathBuf;
 use std::io;
 use std::path::Path;

codex-rs/config/src/loader/mod.rs

@@ -25,7 +25,7 @@ use crate::state::LoaderOverrides;
 use crate::thread_config::ThreadConfigContext;
 use crate::thread_config::ThreadConfigLoader;
 use codex_app_server_protocol::ConfigLayerSource;
-use codex_exec_server::ExecutorFileSystem;
+use codex_file_system::ExecutorFileSystem;
 use codex_git_utils::resolve_root_git_project_for_trust;
 use codex_protocol::config_types::ApprovalsReviewer;
 use codex_protocol::config_types::SandboxMode;

codex-rs/exec-server/Cargo.toml

@@ -17,6 +17,7 @@ base64 = { workspace = true }
 bytes = { workspace = true }
 codex-app-server-protocol = { workspace = true }
 codex-client = { workspace = true }
+codex-file-system = { workspace = true }
 codex-protocol = { workspace = true }
 codex-sandboxing = { workspace = true }
 codex-utils-absolute-path = { workspace = true }

codex-rs/exec-server/src/environment.rs

@@ -3,10 +3,10 @@ use std::sync::Arc;
 
 use crate::ExecServerError;
 use crate::ExecServerRuntimePaths;
+use crate::ExecutorFileSystem;
 use crate::HttpClient;
 use crate::client::LazyRemoteExecServerClient;
 use crate::client::http_client::ReqwestHttpClient;
-use crate::file_system::ExecutorFileSystem;
 use crate::local_file_system::LocalFileSystem;
 use crate::local_process::LocalProcess;
 use crate::process::ExecBackend;

codex-rs/exec-server/src/fs_sandbox.rs

@@ -20,7 +20,6 @@ use tokio::process::Command;
 
 use crate::ExecServerRuntimePaths;
 use crate::FileSystemSandboxContext;
-use crate::file_system::file_system_policy_has_cwd_dependent_entries;
 use crate::fs_helper::CODEX_FS_HELPER_ARG1;
 use crate::fs_helper::FsHelperPayload;
 use crate::fs_helper::FsHelperRequest;
@@ -115,8 +114,7 @@ fn sandbox_cwd(sandbox: &FileSystemSandboxContext) -> Result<AbsolutePathBuf, JS
         return Ok(cwd.clone());
     }
 
-    let file_system_policy = sandbox.permissions.file_system_sandbox_policy();
-    if file_system_policy_has_cwd_dependent_entries(&file_system_policy) {
+    if sandbox.has_cwd_dependent_permissions() {
         return Err(invalid_request(
             "file system sandbox context with dynamic permissions requires cwd".to_string(),
         ));

codex-rs/exec-server/src/lib.rs

@@ -2,7 +2,6 @@ mod client;
 mod client_api;
 mod connection;
 mod environment;
-mod file_system;
 mod fs_helper;
 mod fs_helper_main;
 mod fs_sandbox;
@@ -25,20 +24,20 @@ pub use client::http_client::ReqwestHttpClient;
 pub use client_api::ExecServerClientConnectOptions;
 pub use client_api::HttpClient;
 pub use client_api::RemoteExecServerConnectArgs;
+pub use codex_file_system::CopyOptions;
+pub use codex_file_system::CreateDirectoryOptions;
+pub use codex_file_system::ExecutorFileSystem;
+pub use codex_file_system::FileMetadata;
+pub use codex_file_system::FileSystemResult;
+pub use codex_file_system::FileSystemSandboxContext;
+pub use codex_file_system::ReadDirectoryEntry;
+pub use codex_file_system::RemoveOptions;
 pub use environment::CODEX_EXEC_SERVER_URL_ENV_VAR;
 pub use environment::Environment;
 pub use environment::EnvironmentManager;
 pub use environment::EnvironmentManagerArgs;
 pub use environment::LOCAL_ENVIRONMENT_ID;
 pub use environment::REMOTE_ENVIRONMENT_ID;
-pub use file_system::CopyOptions;
-pub use file_system::CreateDirectoryOptions;
-pub use file_system::ExecutorFileSystem;
-pub use file_system::FileMetadata;
-pub use file_system::FileSystemResult;
-pub use file_system::FileSystemSandboxContext;
-pub use file_system::ReadDirectoryEntry;
-pub use file_system::RemoveOptions;
 pub use fs_helper::CODEX_FS_HELPER_ARG1;
 pub use fs_helper_main::main as run_fs_helper_main;
 pub use local_file_system::LOCAL_FS;

codex-rs/file-system/BUILD.bazel

@@ -0,0 +1,6 @@
+load("//:defs.bzl", "codex_rust_crate")
+
+codex_rust_crate(
+    name = "file-system",
+    crate_name = "codex_file_system",
+)

codex-rs/file-system/Cargo.toml

@@ -0,0 +1,14 @@
+[package]
+name = "codex-file-system"
+version.workspace = true
+edition.workspace = true
+license.workspace = true
+
+[lints]
+workspace = true
+
+[dependencies]
+async-trait = { workspace = true }
+codex-protocol = { workspace = true }
+codex-utils-absolute-path = { workspace = true }
+serde = { workspace = true, features = ["derive"] }

codex-rs/file-system/src/lib.rs

@@ -9,8 +9,8 @@ use codex_protocol::permissions::FileSystemSpecialPath;
 use codex_protocol::permissions::NetworkSandboxPolicy;
 use codex_protocol::protocol::SandboxPolicy;
 use codex_utils_absolute_path::AbsolutePathBuf;
+use std::io;
 use std::path::Path;
-use tokio::io;
 
 #[derive(Clone, Copy, Debug, Eq, PartialEq)]
 pub struct CreateDirectoryOptions {
@@ -99,16 +99,20 @@ impl FileSystemSandboxContext {
             && !file_system_policy.has_full_disk_write_access()
     }
 
-    pub(crate) fn drop_cwd_if_unused(mut self) -> Self {
+    pub fn has_cwd_dependent_permissions(&self) -> bool {
         let file_system_policy = self.permissions.file_system_sandbox_policy();
-        if !file_system_policy_has_cwd_dependent_entries(&file_system_policy) {
+        file_system_policy_has_cwd_dependent_entries(&file_system_policy)
+    }
+
+    pub fn drop_cwd_if_unused(mut self) -> Self {
+        if !self.has_cwd_dependent_permissions() {
             self.cwd = None;
         }
         self
     }
 }
 
-pub(crate) fn file_system_policy_has_cwd_dependent_entries(
+fn file_system_policy_has_cwd_dependent_entries(
     file_system_policy: &FileSystemSandboxPolicy,
 ) -> bool {
     file_system_policy
@@ -125,6 +129,8 @@ pub(crate) fn file_system_policy_has_cwd_dependent_entries(
 
 pub type FileSystemResult<T> = io::Result<T>;
 
+/// Abstract filesystem access used by components that may operate locally or via
+/// a remote executor.
 #[async_trait]
 pub trait ExecutorFileSystem: Send + Sync {
     async fn read_file(

codex-rs/git-utils/Cargo.toml

@@ -11,7 +11,7 @@ workspace = true
 [dependencies]
 anyhow = { workspace = true }
 chrono = { workspace = true }
-codex-exec-server = { workspace = true }
+codex-file-system = { workspace = true }
 codex-protocol = { workspace = true }
 codex-utils-absolute-path = { workspace = true }
 futures = { workspace = true, features = ["alloc"] }

codex-rs/git-utils/src/info.rs

@@ -4,7 +4,7 @@ use std::ffi::OsStr;
 use std::path::Path;
 use std::path::PathBuf;
 
-use codex_exec_server::ExecutorFileSystem;
+use codex_file_system::ExecutorFileSystem;
 use codex_utils_absolute_path::AbsolutePathBuf;
 use futures::future::join_all;
 use schemars::JsonSchema;