feat(tui): async delegation view — docked agents panel + live steering

[JoaoMarcos44]

Summary

Adds an inline, docked agents panel above the composer plus a live steering channel so a running subagent can be redirected by id (@b7c2 switch approach) without killing it. Watch background delegations next to the conversation; steer one mid-flight.

Closes #9.

Motivation

Background delegation and the subagent tree were disconnected: the parked turn was a one-line hint, and the rich tree was a full-screen /agents modal that hid the conversation. There was no way to watch background agents inline, and the only lever on a wrong-headed background fixer was x (kill). This adds visibility and a steering lever.

~80% of the work is reprojection of data that already exists. The one genuinely new capability — inbound steering — reuses the child's existing AIAgent.steer() drain and iteration-boundary interrupt check, so no new core-loop code is introduced.

What changed

Phase 1 — docked read-only panel (low risk)

• delegation.async_list RPC: pure read projection of the async-delegation registry (interrupt_fn already stripped server-side).
• $asyncDelegations store + applyAsyncList; the existing 5s gateway tick populates it alongside delegation.status.
• agentsPanel.tsx: merges live in-turn subagents (turnStore.subagents, freshest tool + elapsed) with background/async rows into one list. Renders nothing when there are no agents.
• Extracted STATUS_GLYPH into a shared module so the panel and the /agents overlay never diverge visually.
• Mounted above the composer next to LiveTodoPanel; header click collapses; ^a opens the full tree.

Phase 2 — live steering (@id)

• send_to_subagent mirrors interrupt_subagent: looks the child up in the live registry and calls AIAgent.steer(text). The child drains it at its next iteration boundary and appends it as a delimited out-of-band user turn on the last tool message — never spliced mid-tool — so role alternation and the prompt cache stay intact.
• subagent.send RPC.
• Composer routes @<id> text to steering only when the token resolves to a live subagent (resolveSteerTargetId), so an ordinary prompt like email @john later falls through to a normal turn untouched. Feedback toast: delivered → @b7c2 / @b7c2 already finished.

Design decisions (deliberate scope calls)

• No per-session ownership guard on send_to_subagent — the live registry carries no session key and interrupt_subagent is already unguarded (holding the id is authority). Same trust model; a guard would require a new registry field. Noted as follow-up.
• Panel actions = read-only + open-tree. Full keyboard kill/inject would hijack the global input router (high risk). Kill stays reachable via the existing /agents overlay; the docked panel delivers the core value — visibility — without that risk.

Testing

53 new tests, all green.

Suite	Covers	Tests
tests/test_async_delegation_view.py	RPC shapes · send_to_subagent · 50-thread concurrency · role-legality · status transitions	15
agentRows.test.ts	merge logic · running/done counts · elapsed clocking · status aliases · fallbacks	16
subagentSteer.test.ts	@id parsing · id/prefix resolution · ambiguity refusal · normal-text passthrough	12
agentsPanel.test.tsx	header counts · empty state · collapse · result ready ⏎ · ^a tree click	6
delegationStoreAsync.test.ts	applyAsyncList populate · null tolerance · replace-not-append · end-to-end	4

Regression: frontend 1385 passed; backend view suite 15/15. The pre-existing failures (terminal*/editor/memory TS suites and 19 test_delegate.py cases) were confirmed identical with this branch reverted — a Python 3.14 _initializer stdlib incompatibility and unrelated suites, with zero references to the new code in any traceback. Build ✓ · lint ✓ · typecheck (touched files) clean.

Files (18 changed · +1101 / −25)

Backend: tools/delegate_tool.py, tui_gateway/server.py
Frontend: components/agentsPanel.tsx · lib/agentRows.ts · lib/subagentGlyph.ts · lib/subagentSteer.ts · app/delegationStore.ts · app/turnStore.ts · app/useSubmission.ts · app/createGatewayEventHandler.ts · components/agentsOverlay.tsx · components/appLayout.tsx · gatewayTypes.ts
Tests: the 5 suites above.

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🖼️ Architecture at a glance

[JoaoMarcos44]

Superseded by the upstream PR NousResearch#70899 (opened against NousResearch/hermes-agent so maintainers can review/edit/merge). Consolidating there.