---
id: host/graphology
name: Implement GraphologyHostConfig — render ujsx template to graphology DAG
status: completed
depends_on:
  - component/operation
  - component/sequential
  - component/parallel
  - component/conditional
  - component/map
  - graph/flowgraph-class
  - schema/edge-attrs
scope: broad
risk: high
impact: phase
level: implementation
---

## Description

Implement the `GraphologyHostConfig` that renders a ujsx workflow template (`UNode` tree) into a graphology `DirectedGraph` DAG. This is the structural analysis rendering path — it validates templates by producing a DAG that can be checked for cycles, type compatibility, and topological ordering.

## Acceptance Criteria

- [ ] `src/host/graphology.ts` exports `GraphologyHostConfig` implementing ujsx `HostConfig<WorkflowTag, GraphNode, GraphContext>`
- [ ] `WorkflowTag: "operation" | "sequential" | "parallel" | "conditional" | "map"`
- [ ] `GraphNode`: `{ key: string; attributes: OperationNodeAttrs | TemplateNodeAttrs }`
- [ ] `GraphContext`: `{ graph: DirectedGraph; parentStack: string[]; operationRegistry?: OperationRegistry }`
- [ ] `createRootContext`: creates fresh `DirectedGraph` with DAG constraints, empty parentStack
- [ ] `createInstance("operation", props, ctx)`: adds graph node with `OperationNodeAttrs`, returns `GraphNode`
- [ ] `createInstance` for structural containers: returns `GraphNode` with synthetic key `__${tag}_${counter++}`, no graph node created (containers are transparent)
- [ ] `appendChild` for Sequential children: creates sequential edges between consecutive siblings (manages `parentStack`)
- [ ] `appendChild` for Parallel children: no inter-child edges, pushes parallel group marker for successor connections
- [ ] `appendChild` for Conditional: creates conditional edge with `dataFlow: true`
- [ ] Edge attributes include `edgeType` and `dataFlow` inference (conservative strategy: conditional always dataFlow: true, sequential with result references → dataFlow: true, otherwise dataFlow: false)
- [ ] `finalizeInstance`: cleans up parentStack after container children are rendered
- [ ] `removeChild`: removes edge between parent and child (structural containers are transparent)
- [ ] `removeChildFromHost`: removes child node from graph and all attached edges
- [ ] Cycle detection after rendering: if `hasCycle()` returns true, throw `CycleError`
- [ ] Re-exported from `src/host/index.ts`
- [ ] Integration tests: render Sequential → assert node/edge structure, render Parallel → assert no inter-child edges, render Conditional → assert conditional edges with dataFlow, nested compositions, cycle detection

## References

- docs/architecture/host-configs.md — GraphologyHostConfig full specification
- docs/architecture/workflow-templates.md — edge creation rules, root node handling, template→DAG conversion
- docs/architecture/schema.md — TemplateEdgeAttrs, dataFlow inference

## Notes

> To be filled by implementation agent

## Summary

> To be filled on completion