Meta Muse is Meta personal AI agent, launched on September 8, 2026. Rather than only answering questions, it is designed to carry out tasks on a user's behalf: it has its own browser, can keep working after the app is closed, and runs in a dedicated Muse Secure VM. In presentation it resembles Grok Bot - a personified agent controlled through conversation - but that is an interface-level analogy, not an assumption of shared architecture.

At 06:45:32 UTC I asked a chat session to spawn 120 subagents at once. Each one had a deliberately trivial job: run sleep 30 in a shell and report a single line back. Thirty-three of those calls created an agent. Eighty-seven failed with the same database error. The aggregated answer never arrived, and the interface eventually showed an Error state. In the durable trace, every one of the 33 created agents reached a terminal completed record - 32 of them with a confirmed workload completion, and one still unresolved - while the record of the parent still said running.

What follows is a black-box investigation of that gap, built entirely from records the runtime wrote to Postgre SQL as it worked: an agent registry, a spawn ledger, per-worker progress tables and a context-item store. The load tests were not re-run to write this article. Everything here was reconstructed from stored state, with one documented exception I will come back to.

Post-publication update - September 13, 2026. I clarified the access scope, added independent architectural context from Rohan Adwankar analysis, separated STAGGERED-80 from the burst-style runs, and described two controls that would better isolate cadence, topology, and concurrency. The experimental data, published CSVs, and figures were not changed.