B8b: develop-mode DAG walk as harness (frontier/MAX_PARALLEL/worktree)

[aarontrowbridge]

Sub-slice of #115. Port the develop-mode DAG walk (Blocked-by/Part-of frontier, MAX_PARALLEL concurrent worktree engineers, branch merge) out of the orchestrator prompt into the harness. The other half of the orchestrator. Blocked by #120. See amico-plugin#29 (the CC-side root-session invariant) — this is the amicode-side re-home.

[Rchari1]

Superseded by #368 Autoresearch Studio — the loop is the product (design-of-record `spec-20260813-162300`, decomposed into WS1–WS7 #371–#375).

The `B*` depth-1 redesign (`spec-20260708-112732`) gated by B0 #107 was never ratified; the harness axis has moved to opencode open + plan-first, telaio by subscription (#398) with:

• WS1 WS3 — QEC pack landing: the second domain proves the interface #371 pack interface — one manifest per domain, score as field of pack (`1922950 WS1 — The pack interface` + follow-up `84a0784`)
• WS4 WS4 — Telaio research rail: campaign interview → skills injection → campaign execution #372 / WS5 WS5 — Campaign machinery: ledger entity, warrant bounds, fleet dispatch, scheduled runs #373 telaio research rail + campaign machinery (warrant-bounded, amico-CLI boundary) — subsumes the orchestrator-dissolution / harness-reframe intent
• Modes: default to plan, retire the pulse-designer agent shell (#389) #395 (`053f952`) plan-first default (`default_agent:plan` at `opencode_config.ts:434`) + pulse-designer retirement

This `B*` slice has had no activity since 2026-07-09 and is now tracked under the WS epics. Closing as superseded — please reopen against #368/WS* if any slice still applies.