Use Claude Code to plan and run a legacy stack migration

An engineer used Claude Code to map, split, and execute a multi-repo migration while keeping each step tied to docs, tickets, and review.

Done with Claude Code· Advanced

What they did
The engineer prepared layered CLAUDE.md files, then gave Claude Code the old repos, read-only access to MySQL and PostgreSQL, and a reference build. Claude first drafted the migration design, while separate reviewer agents checked it from different angles. After that, it created 19 Jira tickets, each with its own design and plan, and worked through them one at a time in separate git worktrees with CI watched in a loop.
How it went
In about 15 work days, the effort produced around 50 tickets and 580 passing tests. The end state had more than 95% API coverage and no bugs or security issues at QA handoff. AI review found only about 30% to 40% of the problems, and the Jira MCP could not connect tickets together.
Tips
This setup depends on strong context files and very careful human review of each design before execution. Watch for tooling limits: the Confluence MCP silently cut off pages above roughly 5KB and overwrote two large docs, and the Bedrock token bill came to close to $5,000.

Try it yourself with Claude Code

I want help migrating [legacy product] from [current architecture] to [target architecture]. First, read the repos and produce a phased migration plan with risks, dependencies, and test strategy. Then help me break the work into tickets, one phase at a time. For each ticket, draft a short design and execution plan, then stop and ask for my approval before you change code, run any irreversible step, merge anything, or touch any live data. Work from [reference implementation or constraints] and keep me updated on tests, CI status, and anything that could block the migration.

Fill in the [brackets]. Agents can make mistakes, so review anything before it is sent, paid or deleted.

Read the original on dev.to ↗

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