debug-widget

Use when debugging a Mendix pluggable widget bug — visual glitch, broken scrolling, missing data, stale state, or interaction bugs that need runtime evidence before fixing.

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/mendix/web-widgets/debug-widget
Any agent
npx skills add mendix/web-widgets --skill debug-widget
Clone the repo
git clone --depth 1 https://github.com/mendix/web-widgets

Made for: Claude Code, Codex.

Per session 37 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,917 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin unknown 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 $0.00037 $0.01917
Opus 5 $0.00018 $0.00958
Sonnet 5 $0.00007 $0.00383
Haiku 4.5 $0.00004 $0.00192

Measured today against content hash 6fa5c0ce020d, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

debug-widget 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 today.

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.

.agents/skills/debug-widget/SKILL.md · 167 lines

How it starts

The opening of the file, as written. The whole thing — 167 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Debug Widget

Overview

Evidence-first debugging for Mendix pluggable widgets. You MUST reproduce the bug with Playwright before reading source code, and MUST verify the fix with Playwright before declaring success.

REQUIRED BACKGROUND: superpowers:systematic-debugging for general root-cause methodology.

Prerequisites

Before starting, confirm with the user:

  1. Test project running? The Mendix app must be live at http://localhost:8080. Ask: "Is the Studio Pro project running?"
  2. MX_PROJECT_PATH set? Needed for deploying the built widget. Ask if not provided.
  3. JIRA/bug description? Extract: widget package, symptom, reproduction steps.

Workflow

Phase 1: Reproduce

  1. Identify the target from the bug report:

    • Widget package (combobox-web, datagrid-web, …)
    • Symptom type — see Bug Categories table below
    • Reproduction steps from JIRA
  2. Find the page — see page-discovery.md

  3. Write a diagnostic Playwright script that follows the JIRA reproduction steps and captures the symptom as a measurable assertion or console output diff.

    See diagnostic-patterns.md for templates by bug category.

    Save it as: packages/pluggableWidgets/<widget>-web/e2e/<bug-id>-diagnostic.spec.js

  4. Run it:

    cd packages/pluggableWidgets/<widget>-web
    npx playwright test e2e/<bug-id>-diagnostic.spec.js --headed
    
  5. Confirm reproduction:

    • Script shows wrong values / assertion fails → proceed to Phase 2
    • Script does NOT demonstrate the bug → fix the script (selectors, timing, page URL). Do NOT proceed to Phase 2 until the script confirms the symptom.

Phase 2: Analyze + Fix

Now you may read source code.

  1. Trace the reactive chain from DOM symptom to root cause. See reactive-chain.md.
    • Simple widgets (combobox, badge): React props → hooks → component render
    • Complex widgets (datagrid, gallery): React props → Gate → MobX stores → Observer components

Read the full file on GitHub · 167 lines

Files

What ships with it

3 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. today First seen · 167 lines · 37 tokens per session scan A 6fa5c0ce020d

Subscribe to this mod's changes

debug-widget is a skill published in the GitHub repository mendix/web-widgets (40 stars, last pushed yesterday), licensed Apache-2.0. It adds 37 tokens to every session and 1,917 once invoked, about $0.0002 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 2026-09-01.