Cargo Workspace Structure

Relevant source files

• BUILD.bazel
• MODULE.bazel
• MODULE.bazel.lock
• SECURITY.md
• codex-rs/Cargo.lock
• codex-rs/Cargo.toml
• codex-rs/app-server-protocol/schema/json/v2/ListMcpServerStatusParams.json
• codex-rs/app-server-protocol/schema/typescript/v2/ListMcpServerStatusParams.ts
• codex-rs/app-server/BUILD.bazel
• codex-rs/app-server/tests/suite/v2/mcp_server_status.rs
• codex-rs/cli/Cargo.toml
• codex-rs/cli/src/debug_sandbox.rs
• codex-rs/cli/src/lib.rs
• codex-rs/cli/src/main.rs
• codex-rs/core/BUILD.bazel
• codex-rs/core/Cargo.toml
• codex-rs/core/src/lib.rs
• codex-rs/core/tests/suite/mcp_tool_cache.rs
• codex-rs/exec/Cargo.toml
• codex-rs/exec/src/event_processor.rs
• codex-rs/tui/BUILD.bazel
• codex-rs/tui/Cargo.toml
• codex-rs/utils/cargo-bin/BUILD.bazel
• defs.bzl
• patches/BUILD.bazel
• patches/llvm_windows_arm64_powl.patch
• patches/llvm_windows_mingw_compat.patch
• patches/rules_rs_build_script_deps_annotation.patch
• patches/rules_rust_windows_msvc_direct_link_args.patch
• patches/v8_bazel_rules.patch
• patches/v8_module_deps.patch
• patches/v8_source_portability.patch
• third_party/v8/BUILD.bazel
• third_party/v8/README.md
• workspace_root_test_launcher.bat.tpl
• workspace_root_test_launcher.sh.tpl

This page covers the layout of the Rust Cargo workspace located at codex-rs/, including crate membership, shared dependency management, and the integration of specialized build tooling like Bazel.

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Workspace Root

The workspace is defined in codex-rs/Cargo.toml codex-rs/Cargo.toml1-129 It uses Cargo's resolver = "2" codex-rs/Cargo.toml130 for feature resolution and sets a shared [workspace.package] block codex-rs/Cargo.toml132-140 that member crates inherit. This centralized configuration ensures that the Rust edition and license remain consistent across all 120+ crates.

Field	Value
resolver	"2" codex-rs/Cargo.toml130
version	"0.0.0" (all crates share the same in-development version) codex-rs/Cargo.toml133
edition	"2024" codex-rs/Cargo.toml138
license	"Apache-2.0" codex-rs/Cargo.toml139

Sources: codex-rs/Cargo.toml1-140

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Crate Membership

The workspace contains over 120 member crates codex-rs/Cargo.toml2-129 These are organized into several functional groups, ranging from the core agent logic to platform-specific utilities.

Key Crates

Core Logic and Engine

Path in workspace	Crate name	Role
core	codex-core	Central agent engine, thread management, and session logic codex-rs/core/src/lib.rs1-203
protocol	codex-protocol	Shared Op/Event protocol types codex-rs/Cargo.toml80
config	codex-config	Configuration loading and validation codex-rs/Cargo.toml34
rollout	codex-rollout	Session persistence and event replay codex-rs/core/src/lib.rs133
models-manager	codex-models-manager	Model discovery and info resolution codex-rs/Cargo.toml76

User Interfaces

Path in workspace	Crate name	Role
cli	codex-cli	The primary codex multitool binary codex-rs/Cargo.toml31
tui	codex-tui	Interactive Terminal User Interface codex-rs/tui/Cargo.toml2-5
exec	codex-exec	Headless execution mode for automation codex-rs/Cargo.toml46
app-server	codex-app-server	JSON-RPC server for IDE integrations codex-rs/Cargo.toml11

Tooling and Infrastructure

Path in workspace	Crate name	Role
codex-mcp	codex-mcp	Model Context Protocol (MCP) client logic codex-rs/Cargo.toml71
mcp-server	codex-mcp-server	Implementation of Codex as an MCP server codex-rs/Cargo.toml72
sandboxing	codex-sandboxing	Cross-platform sandbox abstractions codex-rs/Cargo.toml87
shell-command	codex-shell-command	Shell execution backend codex-rs/Cargo.toml36
otel	codex-otel	OpenTelemetry integration codex-rs/Cargo.toml89

Sources: codex-rs/Cargo.toml2-129 codex-rs/core/src/lib.rs1-203 codex-rs/tui/Cargo.toml1-20

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System Architecture: Code Entity Mapping

The following diagrams bridge high-level system components to their implementation crates and entry points.

Crate-to-Binary Mapping

Sandbox Dispatch Mapping

Sources: codex-rs/tui/Cargo.toml8-15 codex-rs/core/Cargo.toml11-14 codex-rs/cli/src/main.rs90-120 codex-rs/cli/src/debug_sandbox.rs45-162 codex-rs/core/Cargo.toml82

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Dependency Management

The workspace uses a "single source of truth" for dependencies. All shared external and internal dependencies are defined in the root Cargo.toml codex-rs/Cargo.toml141-221 and inherited by member crates.

Dependency Flow

Internal dependencies are mapped to their relative paths in the root manifest:

• codex-core = { path = "core" } codex-rs/Cargo.toml177
• codex-protocol = { path = "protocol" } codex-rs/Cargo.toml222

Member crates reference them using the workspace = true syntax:

• codex-core = { workspace = true } codex-rs/core/Cargo.toml34
• codex-protocol = { workspace = true } codex-rs/core/Cargo.toml59

Sources: codex-rs/Cargo.toml141-221 codex-rs/core/Cargo.toml1-125

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Shared Tooling and Multi-Build Systems

Bazel Integration

In addition to Cargo, the project uses Bazel for hermetic builds and cross-compilation.

• MODULE.bazel: Defines the external dependency graph and build targets MODULE.bazel1-210 It includes platform-specific overrides for LLVM and Abseil to support Windows gnullvm MODULE.bazel7-27
• Toolchains: Registers toolchains for LLVM and nightly Rust MODULE.bazel29 MODULE.bazel197-199
• Patches: The patches/ directory contains Bazel dependency patches for Windows/cross-compilation MODULE.bazel12-16
• MODULE.bazel.lock: Tracks specific versions and hashes of Bazel dependencies MODULE.bazel.lock1-60
• defs.bzl: Contains Bazel macros for defining Rust crates (codex_rust_crate) and handling Windows-specific linker flags defs.bzl10-26 defs.bzl181-192

Development Utilities

• Sccache: Used to accelerate compilation across the workspace.
• Config Schema: codex-write-config-schema codex-rs/core/Cargo.toml12-13 generates JSON schemas for validation of config.toml.
• Rust Toolchain: The project uses the 2024 edition for new workspace crates codex-rs/Cargo.toml138

Sources: MODULE.bazel1-210 codex-rs/core/Cargo.toml11-14 codex-rs/Cargo.lock1-100 MODULE.bazel.lock1-60 defs.bzl1-192