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Use when someone wants to understand or rebuild an app (web, desktop or mobile) from screenshots, screen recordings or normal use, and turn it into a build spec you can use with Base44, ChatGPT or Claude. Not for decompiling app files; for that, use REA itself (github.com/morluto/rea).

Copy the prompt below 👇

<aside> 💡

REA is about 422,000 lines of TypeScript. Most of it plugs heavy tools into an agent (Ghidra, IDA, Android tools, firmware tools, network captures). The part that teaches the agent how to reverse engineer is 789 lines of instructions: its skill file (v38) and 6 guides, attached below. This skill is that method, without the tools.

</aside>

Inputs

Rules

Steps (in this order)

  1. Checklist first. Turn the request into a checklist of questions, and the evidence each answer needs: every screen, every action, every rule, and the data the app stores.
  2. Feature by feature. For each feature: where the user starts, what they do, what changes, what they end up with. Start with the smallest overview, then follow one feature at a time. Never judge behaviour from labels or names alone.
  3. Mark every finding OBSERVED (it is in a screenshot or recording), INFERRED (it must work this way) or UNKNOWN. Say which screenshot each observed finding comes from.
  4. The data. List each table the app must store and its fields, and which screen creates, changes or shows it.
  5. Check the list again. Mark each checklist item answered, partly answered or open. For each open item, say exactly what to click, record or screenshot next. Do not call it complete while items are open.
  6. The build spec. Write a plain spec an app builder can follow. Keep observed behaviour separate from new design choices (your own name, colours and words).

Output