OpenClaw's ACP child sessions inherit subagent security envelope constraints

## Summary ACP child sessions inherit subagent security envelope constraints. ## Affected Packages / Versions - Package: openclaw (npm) - Affected versions: <= 2026.4.21 - Fixed version: 2026.4.22 ## Impact A restricted subagent spawning an ACP child session could fail to carry forward subagent-only constraints such as depth, child-count limits, control scope, or target-agent restrictions. ## Fix ACP spawn now resolves and persists child subagent envelope fields, enforces maximum depth and active-child caps, and applies the inherited control scope to child ACP sessions. ## Fix Commit(s) - 31160dc069b7cc5d833b39c53736a41ad3befda2 ## Verification - The fix commit is contained in the public v2026.4.22 tag. - openclaw@2026.4.22 is published on npm and the compiled package contains the fix. - Focused regression coverage for this path passed before publication. OpenClaw thanks @zsxsoft, @qclawer, and @KeenSecurityLab for reporting.