---
id: analysis/template-validation
name: Implement validateTemplate and validatePreconditions
status: completed
depends_on:
  - analysis/type-compat
  - graph/queries
  - schema/edge-attrs
scope: moderate
risk: medium
impact: component
level: implementation
---

## Description

Implement the template validation functions that check workflow templates against operation graphs, and the precondition validation that verifies all required inputs are provided by predecessors.

## Acceptance Criteria

- [ ] `validatePreconditions(graph: FlowGraph<OperationNodeAttrs, OperationEdgeAttrs>): ValidationError[]` — for each node, checks input required fields are provided by predecessor outputs; returns `ValidationError[]`
- [ ] `validateTemplate(template: UNode, operationGraph: FlowGraph<OperationNodeAttrs, OperationEdgeAttrs>): AnyValidationError[]` — validates template against operation graph
- [ ] Template validation checks: (1) all Operation names exist in registry/graph, (2) no cycles in rendered DAG, (3) type compatibility between sequential operations, (4) reachability from start, (5) no orphan nodes
- [ ] Template validation is advisory — returns warnings AND errors, never throws
- [ ] Both functions follow the "collect all errors" pattern
- [ ] Unit tests: valid template returns empty, missing operation, cycle in template, type incompatibility, unreachable nodes, orphan nodes

## References

- docs/architecture/analysis.md — validatePreconditions, validateTemplate specifications
- docs/architecture/workflow-templates.md — validation checks

## Notes

> To be filled by implementation agent

## Summary

> To be filled on completion