write-script-bunnative

What this skill does

## 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.

# TypeScript (Bun Native)

Native TypeScript execution. Native scripts are Bun scripts that run on the native worker — a lightweight V8 isolate that exposes `fetch` and the JavaScript standard library — and can be heavily parallelized. Every script MUST start with `//native` on its first line so Windmill routes it to the native worker; without it the exact same script runs on the regular Bun worker. You may import npm packages and other Windmill scripts (e.g. `./helper.ts`) — imports are resolved and bundled just like a regular Bun script — as long as everything (your code and its dependencies) relies only on `fetch` and the standard library. Libraries that need Node/Bun runtime APIs (filesystem, `node:*` modules, child processes, native addons) will not work on the native worker; use the regular `bun` language for those.

## Structure

Export a single **async** function called `main`:

```typescript
//native
export async function main(param1: string, param2: number) {
  // Your code here
  return { result: param1, count: param2 };
}
```

Do not call the main function.

## Resource Types

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

Use the `RT` namespace for resource types:

```typescript
//native
export async function main(stripe: RT.Stripe) {
  // stripe contains API key and config from the resource
}
```

Only use resource types if you need them to satisfy the instructions. Always use the RT namespace.

Before using a resource type, check the `rt.d.ts` file in the project root to see all available resource types and their fields. This file is generated by `wmill resource-type generate-namespace`.

## Imports

**The constraint is the runtime, not the import list.** You may import npm packages and relative Windmill scripts; they are resolved and bundled exactly like a regular Bun script. But the native worker only provides `fetch` and the JavaScript standard library, so any imported code must work using only those. Anything requiring Node/Bun built-ins (`node:fs`, `child_process`, the `Bun` API, native modules) belongs in a regular `bun` script instead. Use the globally available `fetch` for HTTP:

```typescript
//native
export async function main(url: string) {
  const response = await fetch(url);
  return await response.json();
}
```

## Windmill Client

`windmill-client` is available for Windmill-specific primitives such as the S3 helpers below (`loadS3File`, `loadS3FileStream`, `writeS3File`, `S3Object`). Use `fetch` for plain HTTP.

## Preprocessor Scripts

For preprocessor scripts, the function should be named `preprocessor` and receives an `event` parameter:

```typescript
//native
type Event = {
  kind:
    | "webhook"
    | "http"
    | "websocket"
    | "kafka"
    | "email"
    | "nats"
    | "postgres"
    | "sqs"
    | "mqtt"
    | "gcp";
  body: any;
  headers: Record<string, string>;
  query: Record<string, string>;
};

export async function preprocessor(event: Event) {
  return {
    param1: event.body.field1,
    param2: event.query.id,
  };
}
```

## S3 Object Operations

Windmill provides built-in support for S3-compatible storage operations. The `wmill.S3Object` type covers both the `s3://storage/key` URI form (`s3:///key` for the workspace default storage) and the `{ s3, storage? }` record form — always use it instead of redefining your own.

### Receiving an S3Object as a script parameter

```typescript
//native
import * as wmill from "windmill-client";

export async function main(file: wmill.S3Object) {
  const content = await wmill.loadS3File(file);
  // ...
}
```

### S3 operations

```typescript
//native
import * as wmill from "windmill-client";

// Load file content from S3
const content: Uint8Array = await wmill.loadS3File(s3object);

// Load file as stream
const blob: Blob = await wmill.loadS3FileStream(s3object);

// Write file to S3
const result: wmill.S3Object = await wmill.writeS3File(
  s3object, // Target path (or undefined to auto-generate)
  fileContent, // string or Blob
  s3ResourcePath // Optional: specific S3 resource to use
);
```


# TypeScript SDK (windmill-client)

Import: import * as wmill from 'windmill-client'

workerHasInternalServer(): boolean

/**
 * Initialize the Windmill client with authentication token and base URL
 * @param token - Authentication token (defaults to WM_TOKEN env variable)
 * @param baseUrl - API base URL (defaults to BASE_INTERNAL_URL or BASE_URL env variable)
 */
setClient(token?: string, baseUrl?: string): void

/**
 * Create a client configuration from env variables
 * @returns client configuration
 */
getWorkspace(): string

/**
 * Get a resource value by path
 * @param path path of the resource,  default to internal state path
 * @param undefinedIfEmpty if the resource does not exist, return undefined instead of throwing an error
 * @returns resource value
 */
async getResource(path?: string, undefinedIfEmpty?: boolean): Promise<any>

/**
 * Get the true root job id
 * @param jobId job id to get the root job id from (default to current job)
 * @returns root job id
 */
async getRootJobId(jobId?: string): Promise<string>

/**
 * @deprecated Use runScriptByPath or runScriptByHash instead
 */
async runScript(path