Claude Code Multiplayer
Build One Shared Workspace for Your Team and Agents in 30 Days
Two agents just rewrote the same file and both reported done. Build the shared workspace that stops it: an owner on every file, a proof gate neither agent controls, a run log that names the first broken step, and your own measured number for one agent against the team.
Your agent finishes. Your teammate’s agent finishes. One of the two writes is gone, and nothing in the system has an opinion about it. No merge conflict, no error, no red text. It looks like success reported twice.
This book builds one shared workspace for a team and its agents, end to end: an owner on every file, a handoff format both agents obey, a gate outside both agents that refuses a false “done”, scoped access with an injection test you re-run after every change, and a run log that names the first broken step instead of the last one.
Every file ships in a free companion repo: thirteen shell gates, one folder per chapter, and fixtures so you can watch each gate refuse and then watch it stay silent.
What You'll Build
Reproduce the silent collision in five minutes: two agents, one file, one write gone, no conflict marker.
Score three of your own tasks on a split-test sheet with your measured cost floor, and reject at least one.
Build a workspace with an index, an owners file, and an inbox a second person can clone and use without a conversation.
Run a two-agent handoff on a six-field message format, with a validator that refuses a malformed one.
Wire a proof gate outside both agents that throws back a "done" on work that does not build.
Add a claim check on every edit that grants the file or refuses the second agent by name.
Give every agent a bounded scope, then attack your own workspace with a hostile handoff and log the refusal.
Log every tool call per agent, then name the step that started a broken run instead of the one that crashed.
Price your last run step by step, name the most expensive one, and build a rate card from it.
Run the revocation test that proves the agent forgets a teammate who left, then hand the next hire a rollout pack.
Schedule a sweep that flags the stale notes every agent still reads, with the next sweep date already written in.
Run the paired benchmark on your own work: one agent against the shared workspace, verdict written down.
Free Articles from this Book
How to Make Two Claude Code Sessions Message Each Other
Hand work from one Claude Code session to another and have the second one start on its own, with nothing copied or pasted. One setting decides it, and left on the default it cost me three messages and about ninety minutes without a single error.
from: Claude Code Multiplayer
How to Debug a Multi-Agent Claude Code Run in One Command
Fix a broken multi-agent Claude Code run with one command that names the step that broke first. It reads one log line per tool call, and in the run shown here the crash was at step 4 while the cause sat two rows earlier, at step 2.
from: Claude Code Multiplayer
How to Check What Claude Code Still Knows After a Teammate Leaves
Put a shared Claude Code setup in front of a team and be able to show what the agent still knows when someone leaves. Two questions and two markers do it, and on my own run the fix I was sure of failed because the answer was still in git history, which sits on the same list as open sessions and saved approvals.
from: Claude Code Multiplayer
How to Share Your Claude Code Project With a Teammate
Bring a teammate onto your project mid-build and have their agent name the right plan without a call. Claude Code has no way to share a session, so we share one index file and a hook that blocks edits when two plans are marked ACTIVE, which is what keeps a 51-day-old handoff document from being read as today's plan.
from: Claude Code Multiplayer
How to Run 2 Claude Code Agents in One Repo Without Losing Work
Run two or more Claude Code agents in one repository and keep every agent's work. One table and one hook turn the second writer away before it touches the file, by name, and I built it after two agents reported the same file done and forty minutes of work was gone.
from: Claude Code Multiplayer