--- title: "Scaling Myself: How I Run 22 Claude Code Sessions for DS4 Migration" url: https://daily.dev/posts/scaling-myself-how-i-run-22-claude-code-sessions-for-ds4-migration-kc0fnrort source_url: https://engineering.mercari.com/en/blog/entry/20260619-scaling-myself-how-i-run-22-claude-code-sessions-for-ds4-migration type: article source: "Mercari Engineering" published: 2026-08-06T00:15:50.919Z updated: 2026-08-06T05:34:17.307Z tags: ["claude-code", "bazel"] reading_time: 13 upvotes: 0 comments: 0 language: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Scaling Myself: How I Run 22 Claude Code Sessions for DS4 Migration **[Mercari Engineering](https://daily.dev/sources/mercari)** · 13 min read · 0 upvotes · 0 comments ## Summary An iOS engineer at Mercari shares how they managed a large-scale design system migration (DS3 to DS4) by running 22 simultaneous Claude Code sessions. The setup relies on git worktrees for parallel branch checkouts without rebuilds, a shared Bazel output cache with a file-based lock protocol, and an Obsidian Vault symlinked to Claude Code's global config as a single source of truth for 35+ custom slash commands encoding the migration playbook. Key practices include dedicated 'brain' sessions for planning vs. execution sessions for coding, a /prune-branches command to handle squash-merge stale branch detection, stacked PR chain management via a single persistent Claude session, and a 'remove and build' verification technique that caught hidden DS3 dependencies in 3 of 21 migrated screens. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [Using Claude Code from Anywhere](https://daily.dev/posts/using-claude-code-from-anywhere-fare4a94d) · Matt Rickard · 1 upvotes · 0 comments - [How I'm Productive with Claude Code](https://daily.dev/posts/how-i-m-productive-with-claude-code-eucievp2e) · Hacker News · 1 upvotes · 0 comments - [Inside the Development Workflow of Claude Code's Creator](https://daily.dev/posts/inside-the-development-workflow-of-claude-code-s-creator-rmtwa51nd) · InfoQ · 2 upvotes · 1 comments - [Claude Code On-The-Go](https://daily.dev/posts/claude-code-on-the-go-aslaulo4t) · Hacker News · 4 upvotes · 0 comments --- Tags: [#claude-code](https://daily.dev/tags/claude-code), [#bazel](https://daily.dev/tags/bazel) [View this post on daily.dev](https://daily.dev/posts/scaling-myself-how-i-run-22-claude-code-sessions-for-ds4-migration-kc0fnrort)