Spec-driven, sub-agent development workflow with a parallel, multi-agent implementation phase — OpenSpec phases (proposal → design → tasks → parallel implementation → verification → archive) with TLA+ design verification. Use when the user wants the spec-driven + TLA+ workflow but with implementation fanned out across multiple concurrent implementer agents, or asks for "parallel implementation", "multi-agent implementer", or "an orchestrator for the implementers". Cross-platform: macOS, Linux, Windows.
