Why: The command bus work (proposal D30) needs the Agent-Command ecosystem
library available to this module before internal/cmdbus lands in T3; wiring
now keeps that task provider-ready.
Evidence: submodule pinned at Agent-Command main 50f99d9 (skeleton + guidelines
pin, merged via its PR #1); go.mod gains only the replace directive — build,
vet and full go test pass with no other change (go mod tidy churn deliberately
excluded).
Impact: No import yet; zero behavior change. Recursive init materializes
guidelines inside agent-command (development-only).
Refs: Agent-System-Documents proposal 2026-09-30-ui-inbox-command-workspace (D30)
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