AgentRoom: Concurrent Multi-Agent Coding in a CRDT-Backed Shared Workspace

Concurrent multi-agent coding promises division of labor across modules and robustness through redundancy. Realtime collaborative editing protocols solve this coordination problem via Conflict-free Replicated Data Types (CRDTs), but the LLMs underneath generate one token at a time and existing multi-agent coding systems inherit this serial limit: they either sequence agents through phase handoffs or pool independent samples without coordination, and a single agent abandons up to 70% of hard tasks with a one-file stub-and-exit. AgentRoom is a realtime collaborative editing protocol for concurrent coding agents: a runtime layer exposing file-level claim, status, and broadcast as MCP tools on top of a CRDT-merged shared filesystem. Across five frontier coding-CLI models on four backend coding tasks, AgentRoom ×2 suppresses Solo abandonment on the CLI-stable models and tightens run-to-run variance. At matched compute, AgentRoom outperforms naive parallel ensembling, and ablating the coordination tools while keeping the CRDT substrate loses most of the gain. Coordination, not parallelism or merge correctness, is what carries the improvement.