Example Task Instructions and API Contract for Evaluating Legacy VB6-to-C# Migration with Coding Agents

This record contains an example of the context files used in an industrial case study that evaluates the migration of a legacy Visual Basic 6 ERP system to C# .NET 10 with three coding agents: Claude Code 2.1.308 with Claude Opus 5.5, Codex CLI 0.163.0 with gpt-6.1-sol, and OpenCode 1.19.4 with DeepSeek V4.1 Flash. Eighteen features from three modules (Measurements, Purchasing and Accounts Payable) were migrated, each run three times per agent, with no human intervention. The example is the feature "Tipos de Consumo" (consumption types, Measurements module, easy level). Every feature had the same two files: - medicoes-facil-v1_instrucoes.md: the task instructions (goal, scope, legacy entry points, migration requirements and conventions), given to the agent as CLAUDE.md or AGENTS.md with identical content for all agents. Across features, only the goal and scope sections change.- medicoes-facil-v1_contrato.md: the fixed API contract (routes, fields and status semantics). The contract states only the shape of the API; business rules come from the legacy code. The standardized prompt that starts each session is given in the paper. The files are in Portuguese, the language of the original system. The legacy source code, the database and the test suite are proprietary and are not included.