---
status: superseded by ADR-0003
---

# LangGraph orchestrates Phases, not Google ADK

Phases are orchestrated by a LangGraph `StateGraph`, as the KAB Workflow Agent standard (`kyndryl-agent-builder/docs/KAB_WORKFLOW_AGENT_IMPLEMENTATION_GUIDE.md`) requires, rather than by Google ADK `Runner`/`LoopAgent`. The earlier "ADK" orchestration was a local compatibility layer that never used the real `google-adk` package, so it added a pretend seam with one adapter and diverged from the platform standard; we deleted it. Real ADK remains welcome *inside* a Phase (e.g. an `LlmAgent` for LLM-driven design) — just not as the thing that sequences Phases.

> **Reopened (2026-09-15).** [ADR-0002](0002-skills-are-the-portable-unit-of-behaviour.md) makes Skills, loaded by a framework's own skill runtime, the portable unit of behaviour. This ADR assumed our code sequences the Phases. If the Skill sequences them instead, the choice here reduces to which skill runtime to wire first, and "ADK only inside a Phase" no longer holds. Still true regardless: the compat stubs are fiction and should go.

## Considered Options

- **Real `google-adk` as orchestrator**: rejected; departs from the KAB workflow standard and would require async event-stream plumbing for no capability LangGraph lacks (conditional edges cover the Review round).
- **Plain in-process pipeline, no framework**: rejected; neither KAB template uses it, and LangGraph already gives us conditional routing and a path to checkpointing if a human approval gate is added later.