feat(cli): Add feature flags for modular CLI builds (#93)

## Summary
🤖 Generated with [Nori](https://www.npmjs.com/package/nori-ai)

- Implemented Cargo feature flags to make the CLI binary modular with
`default = []` (minimal) and `full` (complete) configurations
- Made 6 dependencies optional: `codex-app-server`, `codex-chatgpt`,
`codex-cloud-tasks`, `codex-login`, `codex-mcp-server`,
`codex-responses-api-proxy`, `codex-rmcp-client`
- Added `#[cfg(feature = "...")]` guards throughout `main.rs` for
conditional compilation
- Achieves 22% release binary size reduction (46MB → 36MB) for minimal
builds

## Test Plan
- [x] `cargo build -p codex-cli` (minimal) compiles successfully
- [x] `cargo build -p codex-cli --features full` compiles successfully
- [x] `cargo test --all --features full` passes
- [x] `cargo clippy --all --features full` passes
- [x] MCP integration tests correctly skipped without `mcp-server`
feature

Share Nori with your team: https://www.npmjs.com/package/nori-ai

---------

Co-authored-by: Nori <contact@tilework.tech>
Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

Author: 3 people

codex-rs/Cargo.lock

@@ -15,26 +15,74 @@ path = "src/lib.rs"
 [lints]
 workspace = true
 
+[features]
+default = []
+
+# Full feature set - enables all legacy functionality
+full = [
+    "app-server",
+    "cloud-tasks",
+    "login",
+    "feedback",
+    "backend-client",
+    "upstream-updates",
+    "mcp-server",
+    "chatgpt",
+    "responses-api-proxy",
+    "oss-providers",
+]
+
+# App server functionality
+app-server = ["dep:codex-app-server"]
+
+# Cloud tasks command
+cloud-tasks = ["dep:codex-cloud-tasks"]
+
+# Login/logout commands - propagate to TUI
+login = ["dep:codex-login", "codex-tui/login"]
+
+# Feedback feature - propagate to TUI (legacy OpenAI Sentry feedback)
+# Future Nori feedback: https://github.com/tilework-tech/nori-cli/issues
+feedback = ["codex-tui/feedback"]
+
+# Backend client feature - propagate to TUI
+backend-client = ["codex-tui/backend-client"]
+
+# Upstream updates feature - propagate to TUI
+upstream-updates = ["codex-tui/upstream-updates"]
+
+# OSS providers (Ollama, LM Studio) - propagate to TUI and codex-common
+oss-providers = ["codex-tui/oss-providers", "codex-common/oss-providers"]
+
+# MCP server functionality
+mcp-server = ["dep:codex-mcp-server", "dep:codex-rmcp-client"]
+
+# ChatGPT/apply command
+chatgpt = ["dep:codex-chatgpt"]
+
+# Responses API proxy
+responses-api-proxy = ["dep:codex-responses-api-proxy"]
+
 [dependencies]
 anyhow = { workspace = true }
 clap = { workspace = true, features = ["derive"] }
 clap_complete = { workspace = true }
 codex-acp = { workspace = true }
-codex-app-server = { workspace = true }
+codex-app-server = { workspace = true, optional = true }
 codex-app-server-protocol = { workspace = true }
 codex-arg0 = { workspace = true }
-codex-chatgpt = { workspace = true }
-codex-cloud-tasks = { path = "../cloud-tasks" }
+codex-chatgpt = { workspace = true, optional = true }
+codex-cloud-tasks = { path = "../cloud-tasks", optional = true }
 codex-common = { workspace = true, features = ["cli"] }
 codex-core = { workspace = true }
 codex-exec = { workspace = true }
 codex-execpolicy = { workspace = true }
-codex-login = { workspace = true }
-codex-mcp-server = { workspace = true }
+codex-login = { workspace = true, optional = true }
+codex-mcp-server = { workspace = true, optional = true }
 codex-process-hardening = { workspace = true }
 codex-protocol = { workspace = true }
-codex-responses-api-proxy = { workspace = true }
-codex-rmcp-client = { workspace = true }
+codex-responses-api-proxy = { workspace = true, optional = true }
+codex-rmcp-client = { workspace = true, optional = true }
 codex-stdio-to-uds = { workspace = true }
 codex-tui = { workspace = true }
 ctor = { workspace = true }
@@ -62,3 +110,12 @@ assert_matches = { workspace = true }
 predicates = { workspace = true }
 pretty_assertions = { workspace = true }
 tempfile = { workspace = true }
+
+# Integration tests that require the mcp-server feature
+[[test]]
+name = "mcp_add_remove"
+required-features = ["mcp-server"]
+
+[[test]]
+name = "mcp_list"
+required-features = ["mcp-server"]

codex-rs/cli/Cargo.toml

@@ -10,13 +10,8 @@ The `codex-cli` crate is the main multitool binary that provides the `codex` com
 
 This crate is the primary entry point that ties together all other crates:
 
-- **Dispatches to** `codex-tui` for interactive mode (default, no subcommand)
-- **Dispatches to** `codex-exec` for `codex exec` non-interactive execution
-- **Dispatches to** `codex-mcp-server` for `codex mcp-server`
-- **Dispatches to** `codex-app-server` for `codex app-server`
-- **Dispatches to** `codex-cloud-tasks` for `codex cloud` browsing
-- **Uses** `codex-login` for authentication flows
-- **Uses** `codex-chatgpt` for the `codex apply` command
+- **Always included:** `codex-tui`, `codex-exec`, `codex-acp`, `codex-core` (minimal build)
+- **Optional via features:** `codex-mcp-server`, `codex-app-server`, `codex-cloud-tasks`, `codex-login`, `codex-chatgpt`, `codex-responses-api-proxy`
 - **Uses** `codex-arg0` for arg0-based dispatch (Linux sandbox embedding)
 
 ### Core Implementation
@@ -38,20 +33,20 @@ match subcommand {
 
 **Subcommands:**
 
-| Subcommand | Alias | Description |
-|------------|-------|-------------|
-| `exec` | `e` | Run Codex non-interactively |
-| `login` | | Manage authentication |
-| `logout` | | Remove stored credentials |
-| `mcp` | | Manage MCP server configurations |
-| `mcp-server` | | Run as MCP server (stdio) |
-| `app-server` | | Run app server (JSON-RPC stdio) |
-| `resume` | | Resume previous session |
-| `apply` | `a` | Apply latest Codex diff to working tree |
-| `sandbox` | `debug` | Test sandbox enforcement |
-| `cloud` | | Browse Codex Cloud tasks |
-| `completion` | | Generate shell completions |
-| `features` | | List feature flags |
+| Subcommand | Alias | Description | Required Feature |
+|------------|-------|-------------|------------------|
+| `exec` | `e` | Run Codex non-interactively | (always) |
+| `login` | | Manage authentication | `login` |
+| `logout` | | Remove stored credentials | `login` |
+| `mcp` | | Manage MCP server configurations | `mcp-server` |
+| `mcp-server` | | Run as MCP server (stdio) | `mcp-server` |
+| `app-server` | | Run app server (JSON-RPC stdio) | `app-server` |
+| `resume` | | Resume previous session | (always) |
+| `apply` | `a` | Apply latest Codex diff to working tree | `chatgpt` |
+| `sandbox` | `debug` | Test sandbox enforcement | (always) |
+| `cloud` | | Browse Codex Cloud tasks | `cloud-tasks` |
+| `completion` | | Generate shell completions | (always) |
+| `features` | | List feature flags | (always) |
 
 **Feature Toggles:**
 
@@ -71,6 +66,44 @@ These translate to `-c features.<name>=true/false` config overrides.
 
 ### Things to Know
 
+**Cargo Feature Flags (Compile-time):**
+
+The CLI uses Cargo features to enable optional functionality. By default (`default = []`), only core functionality is included (TUI, exec, ACP). Optional features can be enabled individually or via the `full` meta-feature:
+
+| Feature | Dependencies | Enables |
+|---------|--------------|---------|
+| `full` | All features | Complete legacy binary |
+| `app-server` | `codex-app-server` | `app-server` subcommand |
+| `cloud-tasks` | `codex-cloud-tasks` | `cloud` subcommand |
+| `login` | `codex-login`, `codex-tui/login` | `login`/`logout` subcommands + TUI login |
+| `feedback` | `codex-tui/feedback` | Sentry feedback in TUI |
+| `backend-client` | `codex-tui/backend-client` | Cloud tasks backend client |
+| `upstream-updates` | `codex-tui/upstream-updates` | OpenAI update mechanism (vs Nori's) |
+| `mcp-server` | `codex-mcp-server`, `codex-rmcp-client` | `mcp`, `mcp-server` subcommands |
+| `chatgpt` | `codex-chatgpt` | `apply` subcommand |
+| `responses-api-proxy` | `codex-responses-api-proxy` | `responses-api-proxy` subcommand |
+| `oss-providers` | `codex-tui/oss-providers`, `codex-common/oss-providers` | Ollama/LM Studio local model support |
+
+**Feature Propagation to TUI:**
+
+Several CLI features propagate to the TUI crate for coordinated behavior:
+- `login` -> `codex-tui/login`: Enables login screens and `/login` command in TUI
+- `feedback` -> `codex-tui/feedback`: Enables Sentry feedback and `/feedback` command
+- `backend-client` -> `codex-tui/backend-client`: Enables cloud tasks backend
+- `upstream-updates` -> `codex-tui/upstream-updates`: Uses OpenAI update system instead of Nori's
+- `oss-providers` -> `codex-tui/oss-providers` -> `codex-common/oss-providers`: Enables Ollama/LM Studio local model support
+
+Without these features, the TUI uses Nori-specific alternatives (e.g., GitHub Discussions for feedback, GitHub releases for updates). For OSS providers, the `codex-common` crate provides stub implementations that return `None` or errors when the feature is disabled.
+
+Build examples:
+```bash
+cargo build -p codex-cli                    # Minimal (TUI + exec + ACP only, Nori updates)
+cargo build -p codex-cli --features full    # All functionality (OpenAI-compatible)
+cargo build -p codex-cli --features login,mcp-server  # Selective
+```
+
+Feature-gated code uses `#[cfg(feature = "...")]` on imports, enum variants, match arms, and struct definitions in `main.rs`. Integration tests that require specific features use `required-features` in `Cargo.toml` (e.g., MCP tests require `mcp-server`).
+
 **Sandbox Debugging:**
 
 The `debug_sandbox` module (in `debug_sandbox/`) provides:

codex-rs/cli/docs.md

@@ -1,5 +1,6 @@
 pub mod debug_sandbox;
 mod exit_status;
+#[cfg(feature = "login")]
 pub mod login;
 
 use clap::Parser;