Why

Multi-agent v2 residency is intended to keep only the threads that need to be live. The existing rollout resume path still walked persisted open descendants and reopened the entire descendant tree when resuming a v2 root, which turns resume into an eager reload of work that should stay unloaded until it is explicitly needed.

The interrupted-agent path has a related residency issue. Interrupted agents remain open by design, so an idle interrupted resident should be eligible for eviction just like an idle completed or errored resident. Otherwise a resident set full of interrupted agents can consume every v2 slot and block later spawns or reloads with AgentLimitReached.

What Changed

• Return early from resume_agent_from_rollout after resuming a v2 thread so persisted v2 descendants are not reopened eagerly.
• Treat idle Interrupted v2 residents as unloadable in the LRU residency path.
• Add focused coverage for v2 root resume leaving descendants unloaded and for eviction of an idle interrupted v2 resident when a new slot is needed.

Verification

Added targeted codex-core tests covering:

• v2 root resume with persisted descendants, verifying only the root is loaded after resume.
• residency eviction of an idle interrupted v2 agent when the resident set is full.