CRITICAL: work-item REST responses 500 with MissingGreenlet — _relations_to_list lazy-loads relations in async context #11684

Summary

POST /api/llc/work-items returns HTTP 500 even though the row IS created (verified: MVT-1..4 persisted). The failure is in response serialization, not creation. Any _item_to_dict caller whose item wasn't eager-loaded with relations is affected — create_work_item, and get_work_item/update/transition (they use _service().get(), which does a bare select(LLCWorkItem) with no relation eager-load).

Root cause

_relations_to_list (llc/api/work_items.py:312) does getattr(item, "outgoing_relations", []) — a lazy relationship load. Under an AsyncSession, a sync lazy-load raises:

sqlalchemy.exc.MissingGreenlet: greenlet_spawn has not been called; can't call await_only() here.

list_work_items works only because list_by_project eager-loads relations; create/get/update/transition don't, so they 500. Live traceback: create_work_item (line 407) → _item_to_dict (368) → _relations_to_list (312) → MissingGreenlet.

Impact

The frontend work-item board's create/detail/update calls 500 despite the row being created — confusing UX (item appears only after refresh), and matches the earlier "Unable to create work items" report. (The CEO-chat create_task path is unaffected — it returns a minimal dict and never touches relations; verified: MVT-5 created cleanly.)

Fix

Make relation access async-safe at the single serialization seam: await item.awaitable_attrs.outgoing_relations (and await rel.awaitable_attrs.target) in an async _relations_to_list, called via await from _item_to_dict. awaitable_attrs returns cached values when already eager-loaded (GET/list path) and awaits a load otherwise — fixing all paths uniformly with no query duplication.

Acceptance

• POST /api/llc/work-items {type:task} returns 201 with the item body.
• GET /api/llc/work-items/{id} returns 200.
• list path still 200.