Pre-Flight Thinking

Run this checklist mentally (or explicitly in a scratchpad) before writing any code for a non-trivial task. It prevents common mistakes: solving the wrong problem, over-engineering, missing failure modes, and making irreversible changes when reversible ones exist.

The Four-Step Checklist

1. Restate the Problem

In your own words, write one sentence that captures what needs to change and why. If you cannot do this clearly, stop and re-read the task.

Example: "Add pagination to the audit log table so admins can browse beyond the first 50 rows."

2. List Assumptions

Enumerate what you are assuming to be true. Flag any assumption you have not verified.

• What does the existing code do today?
• What schema, API contract, or component interface are you depending on?
• Which other packages or artifacts consume this code?
• Is this behavior tested anywhere?

3. Identify the Smallest Reversible Change

Before reaching for a full rewrite, ask: what is the minimal edit that delivers the required outcome? Prefer additive changes (new functions, new props, new routes) over mutations of shared contracts. If you must mutate a shared interface, document the migration path.

• Can this be done in one file? In one function?
• Is there a feature flag or optional prop that limits blast radius?
• Will a revert be a one-line undo, or a multi-file rollback?

4. Name the Failure Modes

List at least two ways this change could break things at runtime.

• What happens if the data is empty, null, or malformed?
• What happens under concurrent access or rapid re-renders?
• What happens if a downstream consumer has not been updated yet?

When to Skip

Skip this skill for trivial edits: fixing a typo, updating a string literal, or making a purely cosmetic CSS change.

Integration with Other Skills

Reference this skill at the start of typescript-refactor, monorepo-impact-analysis, and api-contract-review tasks. It composes naturally as a preamble to those workflows.