Developer Manuel Schipper has built a system for running 4-8 parallel coding agents using tmux, Markdown files, and six slash commands. The setup, refined through 300+ feature designs, organizes work across specialized tmux windows: Planner, Worker, and PM roles. Each feature design (FD) follows a structured Markdown format that documents problems, solutions, implementation plans, and verification steps.

Schipper's system tracks FDs through eight lifecycle stages using slash commands like /fd-new, /fd-status, and /fd-deep. The /fd-deep command launches four parallel Opus agents for complex design problems, inspired by GPT Pro's parallel test-time compute. Each FD gets a numbered spec file tracked in an index, with commits automatically tied back to their feature design through naming conventions like FD-049: Implement incremental index rebuild.

A typical FD spans 500-1000 words and includes problem statements, multiple solution options with pros and cons, final implementation plans, and verification steps. The system bootstraps into any repository with /fd-init, creating directory structures, templates, and slash commands. Schipper found that beyond 8 agents, decision quality suffers, making this parallel approach most effective for teams balancing speed with maintainability.