WordPress WP-CLI Internal API

Build, inspect, and extend WP-CLI command code using the documented stable internal API. Use when the task involves custom WP-CLI commands, package bootstrap...

Use this skill when you are writing WP-CLI itself, not merely operating WordPress through wp.

The official internal API reference exposes a stable surface for command registration, logging, hooks, execution, and output formatting. This skill keeps that stable surface close at hand and gives you a quick command skeleton generator.

Use This Skill For

• building custom WP-CLI commands
• reviewing command classes that call WP_CLI::add_command()
• choosing between WP_CLI::log(), success(), warning(), and error()
• formatting output with WP_CLI\Utils\format_items()
• running one WP-CLI command from another with WP_CLI::runcommand()
• using hooks such as WP_CLI::add_hook() and WP_CLI::do_hook()

Do Not Use This Skill For

• normal site administration where a stock WP-CLI command already exists
• REST route implementation or review
• plugin business logic that has nothing to do with WP-CLI command entrypoints

Workflow

1. Stay On The Stable Surface

Read references/stable-internal-api.md.

Start from the officially documented stable methods instead of undocumented internals.

2. Render A Command Skeleton

Use:

scripts/render-command-skeleton.sh --command acme report --class Acme_Report_Command
scripts/render-command-skeleton.sh --command acme report --class Acme_Report_Command --write /tmp/report-command.php

This gives you a minimal command class that already uses:

• WP_CLI::add_command()
• WP_CLI::success()
• WP_CLI\Utils\get_flag_value()
• WP_CLI\Utils\format_items()

3. Choose Output And Error Patterns Deliberately

Read references/command-patterns.md.

Default rule:

• human progress: log() or line()
• successful completion: success()
• non-fatal concern: warning()
• fatal stop: error()

4. Prefer Internal Execution Helpers Over Shelling Out

If a command needs to trigger another WP-CLI command, prefer:

• WP_CLI::runcommand()
• WP_CLI::launch_self()

Reach for generic shell execution only when the task is truly outside WP-CLI.

Files

• scripts/render-command-skeleton.sh: render a minimal custom command class and registration stub
• references/stable-internal-api.md: grouped stable API surface from the official WP-CLI internal API docs
• references/command-patterns.md: practical command-authoring patterns and guardrails