Evidence record / eve
A dated record of one change, kept so the writing that cites it can be checked. Compiled from the sources listed below by the research run, not written for reading. The judgment lives in the issues that cite it, below.
2026-08-10-eve-eve-0-30-7-adds-experimental-persistent-subagent-sessions-so-delegated
eve 0.30.7 adds experimental persistent subagent sessions, so delegated children park instead of terminating.
Behind experimental.subagentPersistentSessions, opted-in agents keep delegated children alive after they answer. Each child is owned by a lifecycle handle, settles every turn with an explicit outcome carrying its per-turn token usage, and parks instead of terminating. The parent's subagent tools gain an agentId parameter to continue a parked child, discoverable from a per-model-call <agents> system injection that lists only parked (resumable) children. An omitted, empty, or unknown agentId starts a fresh child; continuing a child that is still starting or working fails with AGENT_BUSY. Without the opt-in, children keep running as one-shot tasks. A companion fix stops cancellation from leaking child handles as permanently running -- the cancellation epilogue now parks each abandoned child as "(cancelled)" so it stays resumable.
Channel: tagged-release. Ancestry: gh api repos/vercel/eve/releases lists [email protected] published 2026-08-05T17:29:19Z, prerelease=false, draft=false. The feature is gated behind an experimental.subagentPersistentSessions flag in agent.ts -- that is a runtime opt-in inside a stable tag, not a prerelease channel, so the channel is tagged-release and the experimental status belongs in the finding text rather than in the channel.
Operator consequence: Try this if you are paying to re-establish a subagent's context on every delegation. The interesting part for operators is not the resumption, it is that each child settles every turn with explicit per-turn token usage -- that is the accounting hook you need to answer "which subagent is costing me money" without instrumenting it yourself. Do not build a production dependency on it: it is a named experimental flag on a framework that shipped ten minor versions in fourteen days, and the <agents> injection it relies on was itself reworked one release later in 0.31.0 to stop breaking parent resume on models that reject assistant-final requests.
Receipt
Finding metadata
Run: 2026-08-10-weekly-digest-2026-08-03_2026-08-10-frontier-v0
Finding ID: 2026-08-10-eve-eve-0-30-7-adds-experimental-persistent-subagent-sessions-so-delegated
Source links
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Versioned source: run artifact