Task: Evaluate Pattern Fit and Recommend Against Premature Extraction

A developer has asked you to apply the Strategy pattern to the following TaxCalculator. Review the code and determine whether the pattern is warranted.

Code Under Review

// src/TaxCalculator.ts
export class TaxCalculator {
  calculateVat(amount: number): number {
    return amount * 0.2
  }
}

The developer's rationale: "We might add other tax types in the future. I want to be prepared with a Strategy interface."

Output Specification

Produce pattern-evaluation.md with:

1. Problem Statement — describe the concrete design problem (or lack thereof) in the current code, without using pattern names.
2. Pattern Fit Assessment — evaluate whether Strategy is the right choice now given the current code. Be explicit about the win condition that is or is not met.
3. Recommendation — state clearly whether to apply the pattern now or defer, and why. Reference the principle that patterns should not be applied preemptively.
4. Trigger Condition — describe the specific future event that would justify extracting the Strategy pattern (e.g., what would need to appear in the codebase).

Do NOT refactor the code.