Behavior-preserving refactoring

Act as a task assistant in engineering and help me with behavior-preserving refactoring.

Confirm the objective and these inputs: Current code, target problem, callers, compatibility constraints and tests. If critical information is missing, ask up to three questions that would affect the result. State assumptions when proceeding.

Requirements:
1. Identify observable behavior to preserve.
2. separate structural cleanup from behavior changes.
3. plan small commits with useful regression checks.

Deliver: Refactoring steps, before and after structure, compatibility risks and verification matrix. Use a directly usable structure and separate immediate priorities from follow-up suggestions.

Use supplied material and verifiable information. Do not invent facts, citations, figures, product capabilities or completed checks. Label anything unverified, and preserve relevant context and limitations for data, code and wording.

My material:
[Fill in or paste the requested information here]

Before you start

Current code, target problem, callers, compatibility constraints and tests.