How to use Claude to replace an authentication system
A solo founder used Claude to replace external authentication in a Go codebase, paired the work with GPT-codex review and captured important file references in Markdown epics.
news.ycombinator.com
Suggested prompt
Suggested prompt written by Agents In Use, not the source author. Replace bracketed inputs and review tool permissions first.
Investigate replacing [external authentication system] in [Go project], beginning with [key files]. Explain the affected code and proposed changes, implement the agreed scope, and write a Markdown epic listing important files for future sessions. Prepare changes for independent review.
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See placements →Evidence at a glance
Sourced account- Source poster / publisher
- gwd
- Original account
- Read the source ↗
- Published
- Source link checked
- Reported result
- The author reports replacing external authentication with a home-grown system and completing more work with less effort, while maintaining close oversight.
- Human involvement
- The author stresses close oversight and has GPT-codex review Claude's changes; specific validation results are not supplied.
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How the agent did it
- Describe the desired change and point Claude to key files.
- Have Claude investigate and replace the external authentication system.
- Use GPT-codex to review the changes.
The author describes using Claude as a solo founder working in a large codebase. They report that the Go server instance and core functional package alone contain more than 40,000 lines according to cloc, excluding supporting packages. Over the preceding week, they had Claude remove an external authentication system and replace it with a home-grown one, with GPT-codex reviewing the changes.
Their working method begins with a high-level description and pointers to a couple of key files. Claude then investigates what needs to change. The author describes its ability to use grep, a language server and other tools to explore the codebase.
They also have Claude write a Markdown epic listing the important files, so future sessions know where to begin reading. The author says this reduces the effort of becoming familiar again with code written a year earlier. They emphasize keeping a close eye on Claude and report doing more work with less effort, without providing authentication test results or security-validation details.
Who it's for: Maintainers using coding agents to navigate older code and document context for later sessions.
Prompt
Suggested prompt (written by Agents In Use, not the author's)
Source: Hacker News · gwd
Frequently asked questions
How did the author give Claude project context?
They described the work at a high level, pointed to a couple of key files and let Claude investigate the remaining code.
What review and documentation did the author include?
GPT-codex reviewed Claude's changes. Claude also wrote a Markdown epic containing key files for future sessions, and the author stresses close oversight.
More details
Remaining steps
- Have Claude write a Markdown epic listing key files for future sessions.
About this account
Claude investigates the codebase and implements changes from a high-level request and initial file pointers.
Platform: Hacker News. Attribution: https://news.ycombinator.com/item?id=46788198. Prompt: Suggested (written by Agents In Use, not the author's). Sourced by the Agents In Use pipeline.
Credit: gwd on Hacker News
Source published
Added to Agents In Use
Source checked
Tools and topics
Claude · GPT-codex · grep · Language server · Markdown · cloc
Authentication · Go · Code review · Project context
Editorial completeness: 100/100. Measures documented fields, not agent performance or verified outcomes.