Motivation

• Provide a low-churn, reuse-first path to implement QM2 Phase 1 by mapping coordination concepts to existing OpenClaw primitives.
• Reduce risk and rollout scope by favoring existing event, hook, queue, and lane primitives rather than introducing new transports or policy engines in Phase 1.

Description

• Adds a new "Minimally Invasive Implementation Plan (Reuse-First)" section to _shared/specs/qm2-agent-coordination.md that identifies extension points to reuse: the agent event stream, subagent lifecycle events, plugin hook framework, durable delivery queue, and lane-based command queue.
• Recommends a Phase 1 integration shape that introduces lightweight contracts/types, optional envelope passthrough, logical lanes mapped onto enqueueCommandInLane, ledger-as-event-projection (initially emitted to agent events), deterministic rule-based arbitration, and escalation via existing HITL hooks.
• Codifies compatibility and risk controls including a feature-gate (coordination.phase1.enabled), backward-compatible no-envelope behavior, idempotency semantics for replay, and an incremental PR-by-slice rollout sequence.
• Documents explicit non-goals for Phase 1 (no new transport, no exact-once guarantee, no LLM-driven arbitration, no full policy DSL, no UI dependency).

Testing

• This is a documentation-only change; no runtime behavior was modified and no automated unit/integration tests were required for the change.
• Validation consisted of inspecting the updated spec file and verifying the diff and file contents were as expected using local file checks.
• All local verification steps completed without error.

Codex Task