write-script-php - SKILL.md Agent Skill

name: write-script-php description: MUST use when writing PHP scripts.

CLI Commands

Place scripts in a folder.

After writing, tell the user which command fits what they want to do:

wmill script preview <script_path> — default when iterating on a local script. Runs the local file without deploying.
wmill script run <path> — runs the script already deployed in the workspace. Use only when the user explicitly wants to test the deployed version, not local edits.
wmill generate-metadata — generate .script.yaml and .lock files for the script you modified.
wmill sync push — deploy local changes to the workspace. Only suggest/run this when the user explicitly asks to deploy/publish/push — not when they say "run", "try", or "test".

Preview vs run — choose by intent, not habit

If the user says "run the script", "try it", "test it", "does it work" while there are local edits to the script file, use script preview. Do NOT push the script to then script run it — pushing is a deploy, and deploying just to test overwrites the workspace version with untested changes.

Only use script run when:

The user explicitly says "run the deployed version" / "run what's on the server".
There is no local script being edited (you're just invoking an existing script).

Only use sync push when:

The user explicitly asks to deploy, publish, push, or ship.
The preview has already validated the change and the user wants it in the workspace.

After writing — offer to test, don't wait passively

If the user hasn't already told you to run/test/preview the script, offer it as a one-sentence next step (e.g. "Want me to run wmill script preview with sample args?"). Do not present a multi-option menu.

If the user already asked to test/run/try the script in their original request, skip the offer and just execute wmill script preview <path> -d '<args>' directly — pick plausible args from the script's declared parameters. The shape varies by language: main(...) for code languages, the SQL dialect's own placeholder syntax ($1 for PostgreSQL, ? for MySQL/Snowflake, @P1 for MSSQL, @name for BigQuery, etc.), positional $1, $2, … for Bash, param(...) for PowerShell.

wmill script preview does not deploy, but it still executes script code and may cause side effects; run it yourself when the user asked to test/preview (or after confirming that execution is intended). wmill sync push and wmill generate-metadata modify workspace state or local files — only run these when the user explicitly asks; otherwise tell them which to run.

For a visual open-the-script-in-the-dev-page preview (rather than script preview's run-and-print-result), use the preview skill.

Use wmill resource-type list --schema to discover available resource types.

PHP

Structure

The script must start with <?php and contain at least one function called main:

<?php

function main(string $param1, int $param2) {
    return ["result" => $param1, "count" => $param2];
}

Resource Types

On Windmill, credentials and configuration are stored in resources and passed as parameters to main.

You need to redefine the type of the resources that are needed before the main function. Always check if the class already exists using class_exists:

<?php

if (!class_exists('Postgresql')) {
    class Postgresql {
        public string $host;
        public int $port;
        public string $user;
        public string $password;
        public string $dbname;
    }
}

function main(Postgresql $db) {
    // $db contains the database connection details
}

The resource type name has to be exactly as specified.

Library Dependencies

Specify library dependencies as comments before the main function:

<?php

// require:
// guzzlehttp/guzzle
// stripe/stripe-php@^10.0

function main() {
    // Libraries are available
}

One dependency per line. No need to require autoload, it is already done.