🔍 Read the full analysis: How To Give An AI Agent A Starting Point In Any Codebase on ThorstenMeyerAI.com
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TL;DR
A ThorstenMeyerAI.com article published Oct. 19 describes how developers can use Reverse Engineer Anything (REA) to help coding agents inspect existing software. It presents five investigations, including how to frame a focused question, verify the tool connection and check whether an agent’s explanation is supported by evidence.
ThorstenMeyerAI.com published a guide on Oct. 19 to using Reverse Engineer Anything (REA), an open-source toolkit that lets coding agents inspect existing software, with a focus on asking narrow questions and checking the evidence behind the answers. The article presents five investigations intended to help developers turn observed program behavior into specifications for new software, while warning that agent findings can be guesses if REA is not connected or results are not verified.
The guide describes REA as a combination of a local Model Context Protocol (MCP) server, a command-line tool and an agent skill. Coding agents can use it to analyze different kinds of software, including native applications, JavaScript and Electron programs, .NET and Android apps, firmware, databases and browser behavior. Native program analysis can rely on tools such as Ghidra, Hopper or IDA. The article says the project supports agents including Claude Code, Codex, Cursor and Gemini CLI.
Its first recommendation is to define one behavior and the decision it informs, rather than asking an agent to explain an entire program. For example, a developer might ask how a partial invoice payment changes the balance and which account receives the posting. The guide says a useful answer should identify stored data, calculations and conditions that change the result, and distinguish what was observed from what was inferred or remains unknown.
The setup instructions call for Node.js 22.19 or newer, an agent connection and a check that the tools actually loaded. The article cautions that REA’s diagnostic command checks files and prerequisites, not whether the live agent connection works. It recommends confirming the connection inside the agent and testing with a program the user owns. The source describes five investigations, but the supplied material ends partway through its third, so details of the remaining examples are not available here.
Infographic 01 · Reverse Engineer Anything
Five places to point REA first, and how to tell when the answer is wrong.
REA gives coding agents such as Claude Code and Codex tools to inspect programs, apps and browser sessions. Each investigation needs a finishable question and a check.
npx rea-agents@latest setupThe five investigations
What to ask, and the check that catches a wrong answer.
- 1
Ask a question you can finish
One behaviour, one decision it informs. Example: how a partial payment changes an invoice balance.
It’s wrong ifThe agent can't walk through one concrete example with real inputs and outputs. - 2
Get REA connected and confirmed
Run the guided setup, then doctor, then call binary_session inside the agent before any real target.
It’s wrong ifAnswers arrive without a single REA tool call: you're reading the model's guesses. - 3
Turn a business rule into a spec
Inputs, stored fields, formula, edge cases, plus test cases checked against the original's own output.
It’s wrong ifYour version and the original disagree on a test case, even by one cent. - 4
See what has to survive a copy
Find what an app writes to the clipboard and what it keeps locally, then design your own copy and paste.
It’s wrong ifThe explanation doesn't predict what lands in a plain text editor, an email and your app. - 5
Your own app, your equipment, an old program
Start with software you own or rely on. Ask what it sends, stores or calculates when you do one thing.
It’s wrong ifIt only works for the example you watched. Test with a new file or a read-only command first.
Sources: REA on GitHub (stars via GitHub API, 19 Oct 2026); REA installation guide; REA security policy.
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From Software Behavior to Specifications
The approach matters because a program’s interface does not reveal all the rules behind it. A new application can look convincing while mishandling calculations, stored records or conditional behavior. The guide argues that inspecting an existing program can help developers identify those rules before building a replacement or related tool.
The article highlights Ledger Reborn, a local accounting application its author says was built after investigating QuickBooks Desktop. According to the source, the app’s profit-and-loss statement, balance sheet and trial balance for Intuit’s official sample company matched the original account by account, to the cent. That is a reported result from the case study, not independent verification in the material provided. The example illustrates the potential value of a concrete test, while also showing why claims about accuracy need a named dataset and comparison method.
For readers using coding agents, the practical point is that tool access alone does not establish correctness. A developer needs to check that REA was called, ask for a complete example with inputs and outputs, and label evidence separately from inference. Those steps can make an investigation more useful, but they do not guarantee that every conclusion is correct.
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How REA Fits Into Agent Work
REA is identified in the article as an MIT-licensed project on GitHub, under the repository name morluto/rea. The source reports that version 6.7.0 was released on Oct. 18, 2026, and that the project had about 325,000 stars and 82,000 forks on Oct. 19. Those figures are a dated snapshot reported by the source, not a measure of the tool’s accuracy or adoption in production.
The featured accounting investigation used QuickBooks Desktop for Mac 2024, REA version 6.4.0 and Ghidra, according to the article. Its scope included inventory arithmetic, how account types affect budget number signs, reconciliation balances and cash-basis report paths. The case study’s stated purpose was to understand program behavior and inform a separate application, rather than to reproduce its screens alone.
REA runs analysis locally, but the guide says results are passed to the coding agent and may also reach the model provider under that provider’s data policy. It quotes the project warning, “This is not a sandbox.” An unknown program may be handled by analysis tools with the user’s permissions, so local execution should not be confused with isolation from risk.
“This is not a sandbox.”
— REA project, as quoted in the ThorstenMeyerAI.com article
software reverse engineering toolkit
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Limits of the Reported Findings
The supplied source is incomplete: it ends during the third investigation and does not provide the full text of the case study or the remaining two investigations. Details about their methods and conclusions cannot be established from the material available. The source also does not include independent testing of the reported Ledger Reborn comparison, so its account-by-account result remains an attributed claim.
It is also not clear from the supplied material how REA’s different analysis engines perform across all supported software types, or how often agents produce incorrect interpretations despite using the tools. The guide’s setup check cannot verify a live connection on its own, and the article does not provide a broader reliability rate. Users should treat agent explanations as findings to test, not as proof of a program’s behavior.
The source reports that REA runs locally, but says analysis results reach the agent and may be handled by its model provider under that provider’s data policy. The specific data handling terms depend on the agent and provider; the article does not establish one policy that applies to every setup.
program inspection and debugging tools
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Verify the Connection and Test
The immediate steps in the guide are to install REA with its guided setup, review the proposed changes, restart the coding agent and check prerequisites. Developers should then confirm tool use inside the agent, since the diagnostic command does not test the live connection, before pointing it at a harmless program they own.
For a substantive investigation, the article recommends choosing a bounded behavior, stating the decision the answer will inform and asking for one complete example. The agent should separate observed, inferred and unknown details. Developers can then compare the explanation against program outputs or other available evidence. The source gives no separate future release date or follow-up announcement; its guidance is to validate each investigation as it is carried out.
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Key Questions
What is Reverse Engineer Anything?
REA is an open-source toolkit described as a local MCP server, command-line tool and agent skill. It lets compatible coding agents call analysis tools to inspect existing software.
Which coding agents does the article name?
The guide names Claude Code, Codex, Cursor and Gemini CLI, among other agents. The available source does not provide a complete compatibility list.
How can a developer check that REA is connected?
The guide says to run the diagnostic for files and prerequisites, then confirm tool use inside the agent. The diagnostic does not test the live agent connection, so an answer produced without an REA tool call may be based on the model’s prior knowledge or guesswork.
Does local analysis mean a program is isolated?
No. The article quotes the project warning that REA is not a sandbox. Analysis tools may run with the user’s permissions, and results may be sent to the agent or model provider under their data policies.
What remains unverified about the accounting example?
The article reports that Ledger Reborn matched QuickBooks Desktop’s statements for an official sample company to the cent. The supplied material does not include independent verification or the complete case study, so that result should be treated as an attributed claim.
Source: ThorstenMeyerAI.com
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