writing-scripts

A guide to writing JavaScript functions that run at defined points in a Celigo data pipeline. These scripts add custom logic when ordinary filters, expressions, or mappings are not enough.

In plain words
What is it for?
Use it to create or edit scripts for filtering, transforming, routing, calculations, API calls, and other flow, API, or tool processing.
Why use it?
It helps choose the correct pipeline hook, follow the required input and output formats, and diagnose script behavior.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/celigo/ai/writing-scripts
Any agent
npx skills add celigo/ai --skill writing-scripts
Clone the repo
git clone --depth 1 https://github.com/celigo/ai

Made for: Claude Code, Codex.

Per session 62 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 5,385 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00062 $0.05385
Opus 5 $0.00031 $0.02693
Sonnet 5 $0.00012 $0.01077
Haiku 4.5 $0.00006 $0.00539

Measured 2d ago against content hash cdb782c9e786, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

writing-scripts scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/writing-scripts/SKILL.md · 337 lines

How it starts

The opening of the file, as written. The whole thing — 337 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Writing Scripts

A script is a JavaScript function that runs at a specific hook point in the Celigo data pipeline. Scripts handle logic that expressions, filters, and visual mappings cannot -- complex conditionals, cross-record calculations, API calls within the pipeline, and custom routing.

Concerns when writing a script:

  • Choosing the right hook point -- which function type matches what you're trying to accomplish
  • Input/output contracts -- what options contains and what the function must return (array length rules are strict)
  • Expression alternative -- filter, transform, and output filter have expression-based alternatives that don't require a script; prefer expressions when possible
  • Available modules -- scripts can import three built-in modules: integrator-api (call Celigo APIs), dayjs (date/time manipulation), and sjcl (Stanford JavaScript Crypto Library for hashing/encryption)
  • One script, many functions -- a single script resource can contain multiple exported functions, each wired independently to different hook points

Used across flows, APIs, and tools.

Hook Points

Every script function runs at a specific point in the pipeline. Choose based on when you need to act and what data you need access to.

Data Pipeline Hooks

Hook Runs on When Input Must return
preSavePage Export After retrieval, before pipeline options.data[], errors[], files[], retryData{} { data[], errors[], abort, newErrorsAndRetryData[] }
preMap Import Before field mapping options.data[] (unmapped records) Array matching data.length: { data }, { errors }, or {} to skip
postMap Import After field mapping, before submit options.preMapData[], postMapData[] Array matching postMapData.length: { data }, { errors }, or {} to skip
postSubmit Import After destination submission options.preMapData[], postMapData[], responseData[] responseData[] (same length, modified)
postAggregate Import After file aggregation upload options.postAggregateData: { success, _json, code, message } void

Read the full file on GitHub · 337 lines

Files

What ships with it

2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 337 lines · 62 tokens per session scan A cdb782c9e786

Subscribe to this mod's changes

writing-scripts is a skill published in the GitHub repository celigo/ai (3 stars, last pushed 4d ago), licensed MIT. It adds 62 tokens to every session and 5,385 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

Related

Other skills, from other repositories