Summary

Normal top-level sessions can inherit stale subagent lineage metadata, which causes later ordinary runs to be treated as nested child sessions. That can make sessions_spawn fail with depth-limit errors like:

• sessions_spawn is not allowed at this depth (current depth: 2, max: 1)

...even when the visible conversation is a normal top-level group/direct chat.

Root cause

Session metadata for ordinary turns currently preserves subagent lineage fields from prior state:

• spawnedBy
• spawnDepth
• subagentRole
• subagentControlScope
• related parent lineage fields

Later normal runs can then reuse the stored lineage instead of only using live spawned-session context.

Depth checks in sessions_spawn ultimately derive nesting from this persisted lineage, so stale metadata can make an ordinary chat turn look like a nested session.

Impact

• normal chats can lose the ability to spawn subagents
• behavior is confusing because the visible session looks top-level
• failures are sticky because the stale lineage keeps being persisted across future turns

Proposed fix

• clear subagent lineage fields on ordinary top-level session turns
• preserve lineage only for actual spawned/subagent sessions
• avoid reusing stale sessionEntry.spawnedBy as normal-run spawn context
• add regression coverage for a top-level session after stale lineage was previously present

Notes

This appears to be a product bug in session-state persistence/reuse, not a configuration problem.