Migrate a legacy product stack with Claude Code
An engineer ran a proof-of-concept that consolidated 4 repos into 2, moved MySQL to PostgreSQL, upgraded frameworks and replaced the auth model, in about 15 work days.
Done withClaude Code
- What they did
- The engineer wrote layered CLAUDE.md context files and gave Claude Code the legacy repos, read-only MySQL and PostgreSQL connections, and a reference implementation. Claude drafted the design, and parallel reviewer agents stress-tested it. Claude then made 19 Jira tickets. Each ticket got a design doc and plan doc that he reviewed, then ran in its own git worktree, with CI monitored through a loop.
- How it went
- About 15 work days produced roughly 50 tickets and 580 passing tests, with 95%+ API coverage and zero bugs or vulnerabilities at QA handoff. AI review caught only 30-40% of issues, and the Jira MCP could not link tickets.
- Worth knowing
- Cost was close to $5,000 in Bedrock tokens, mostly up front. Also, the Confluence MCP silently truncated pages over about 5KB, overwriting two large design docs.
Try it yourself with Claude Code
I want a proof-of-concept migration of [legacy product] from [current stack, e.g. 4 repos, MySQL, old framework version] to [target stack, e.g. 2 repos, PostgreSQL, current framework]. Start by reading the codebases and writing a phased migration plan with risks, then execute the first phase on a new branch with tests passing. Pause for my review before merging anything or running changes against any real database.
Source: dev.to · Undated
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