feat(ag-ui): subagent cards over AG-UI via native ACTIVITY events (F5)#668
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Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Subagent cards over AG-UI via the protocol's native ACTIVITY events (activityType=subagent), not a private CUSTOM convention. Three layers: generic ACTIVITY reducer + subagent projection (libs/ag-ui); owned server-side LangGraphAgent.run() transform mapping subagent intent to ACTIVITY events; reference graph emits the intent. Reusable activity infra; CUSTOM->native migration of state/interrupt/a2ui deferred. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
…+ stateless transform Override the bridge's 1:1 _dispatch_event to convert the subagent_activity custom event to an ACTIVITY event; the handler sends accumulated text_so_far (like A2uiPartialHandler's args_so_far) so the transform stays stateless. run()-wrap / custom-route are documented fallbacks. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
…(8 tasks) Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
… ACTIVITY (_dispatch_event) Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
…ot get_stream_writer) The installed ag_ui_langgraph bridge drives the graph with astream_events and converts on_custom_event callbacks to AG-UI CUSTOM events; get_stream_writer surfaces only as RAW. Correct L3 emission in spec + plan T2. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
… value (review) Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
… via adispatch_custom_event Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
…dling Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
…ble identity) Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Unbounded growth + stale-binding if a tool-call-id is reused after a RUN_STARTED reset. Prune wrappers not present in the current activities. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
…ld text isolated Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
…iew) Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
…cards Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
…vent, not get_stream_writer) Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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Closes finding F5 from the Phase-2 capability audit: surface a live subagent card over the AG-UI transport. Spec: `docs/superpowers/specs/2026-06-15-ag-ui-subagent-cards-design.md`; plan: `docs/superpowers/plans/2026-06-15-ag-ui-subagent-cards.md`.
Approach — speak the protocol natively
AG-UI's wire is flat (no native subagent identity), and the LangGraph subgraph namespace the canonical adapter keys on doesn't survive the bridge. Rather than invent a private CUSTOM convention, this models a subagent run as the protocol's native ACTIVITY events (`activityType: "subagent"`) — so `@threadplane/ag-ui` consumes the protocol primitive and any compliant AG-UI server that emits subagent activities lights up the card, no private convention required. The generic activity infrastructure is reusable for future activity types.
Three layers + a cockpit capability
A T1 spike de-risked the load-bearing seam and corrected the emission API: this bridge drives the graph with `astream_events`, so `adispatch_custom_event` (on_custom_event → CUSTOM → `_dispatch_event`) is required — `get_stream_writer` surfaces only as RAW.
Consumer-visible surface change (`@threadplane/ag-ui`)
`AgUiAgent` now exposes a non-optional `subagents: Signal<Map<string, Subagent>>` (was inherited optional from `Agent`). `libs/ag-ui` has no CHANGELOG file (only `libs/chat` does, per repo convention) — flagging here so the next patch release documents the new `subagents` surface.
Verification
Out of scope (logged follow-ups)
Migrating the existing CUSTOM events (`state_update`/`on_interrupt`/`a2ui-partial`) to native `STATE_*`/HITL/`TOOL_CALL_ARGS` — a separate brainstorm; the L2 module is where they'd land. Plus the residual NG0956 during json-render spec assembly and a2ui icon-catalog support.
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