[coordination][deferred] Typed task/handoff model (owner/status/result)

[serge-ivo]

DEFERRED. Promote the minimal task handle from the near-term work into a first-class coordination record — task → owner → status → result — on the existing board + coding_timeline, so ALL delegation (not just Coder's) is observable + resumable. Part of #154.

[serge-ivo]

Scope addition from docs/supervision.md: the typed task model also needs to carry the escalation ladder.

Under multi-layer supervision (#183), when a subordinate hits needs_human it should surface to its supervisor first — which may resolve it without waking anyone — and reach the actual human only after a bounded number of hops.

Without this, multi-layer supervision multiplies human interrupts, which is exactly backwards: the point of a hierarchy is to absorb them.

Related: goals also need a completion predicate and a deadline. #154's complaint about the old one-shot was fire-and-forget; "waits forever" is the opposite failure and just as real — supervisors block and the board fills with permanent running.

[serge-ivo]

Escalation ladder done in f5f521a (lib/escalation.ts). An escalation climbs to the supervisor first and reaches the human only at the root or once hops are spent — so three subordinates under one Lead stop meaning three pings to the same person.

Deliberately tells, does not trigger: the supervisor gets a board card and a note naming the subordinate, its objective and what it can do next. Auto-resolution starts spending unprompted and belongs behind its own gate.

The typed task/handoff half of this ticket (owner/status/result as a first-class record) is not done — delegated runs are tracked via agent_loop_runs + board cards, which covers observability but is not the unified model this ticket described. Reopening as a follow-up if that shape is still wanted.