# Add CLI Argument

> Add or change a ModelExpress client CLI argument or environment variable. Use whenever touching ClientArgs, ClientConfig::load(), the Cli struct, or envs.rs/envs.py.

- Skill: `ai-dynamo/add-cli-argument` (Agent Skill)
- Install (CLI): `npx skillmds@latest add ai-dynamo/add-cli-argument`
- Raw SKILL.md: https://api.skillmd.com/api/skills/ai-dynamo/add-cli-argument/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: ai-dynamo (https://skillmd.com/u/ai-dynamo)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/ai-dynamo/add-cli-argument

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# Adding CLI Arguments

Client CLI arguments are defined in a shared struct to avoid duplication:

1. **Add to `ClientArgs`** in `modelexpress_common/src/client_config.rs`
   - Single source of truth for shared arguments
   - Register the variable name in `modelexpress_common/src/envs.rs` and reference the constant: `#[arg(long, env = crate::envs::MODEL_EXPRESS_...)]` (never a bare string literal, so the CLI and the `envs` getters cannot drift). All env-var names live in `modelexpress_common/src/envs.rs` (Rust) and `modelexpress/envs.py` (Python).
   - Do NOT use `-v` short flag (reserved for CLI's verbose)

2. **Update `ClientConfig::load()`** in the same file
   - Add override logic in the "APPLY CLI ARGUMENT OVERRIDES" section

3. **Do NOT duplicate in `Cli`** (`modelexpress_client/src/bin/modules/args.rs`)
   - `Cli` embeds `ClientArgs` via `#[command(flatten)]`
   - Only add CLI-specific arguments there (e.g., `--format`, `--verbose`)

4. **Add tests** in the `tests` module of `client_config.rs`