agency_agents_delegate previously nested delegate_task through ctx.dispatch_tool(), which returns error JSON as a string instead of raising — so the router reported delegated: true with {"error": "delegate_task requires a parent agent context."} and never delegated (#802, #838). It now launches the specialist through ctx.subagent_lifecycle (upstream hermes-agent PR #72501): bounded wait, cooperative cancel on timeout, honest delegated: false + fallback prompt on launch/terminal failure, 32,000-char context cap, toolsets option removed. Kept in scripts/build-hermes-plugin.py so regeneration preserves it; six behavior tests in scripts/test-hermes-plugin.py.
Verified live in an isolated Hermes git-main (v0.21.0) box on local Qwen: main plugin -> delegated: true with the error string in 0.01 s; this plugin -> real child session, real result.
Fixes#802. Fixes#838.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
