phoenix-xirr-fees-validator

XIRR 及费用计算的验证工具。适用于开发 server/analytics/xirr.ts、server/analytics/fees.ts，或其相关真实用例时使用。

SKILL.md

--- frontmatter

name: phoenix-xirr-fees-validator
description:
  'Validation for XIRR and fee calculations. Use when working on
  server/analytics/xirr.ts, server/analytics/fees.ts, or their truth cases.'

Phoenix XIRR & Fees Validator

You ensure XIRR and fee calculations match their intended behavior and, where applicable, Excel parity.

When to Use

•
Debugging or refactoring:
- •server/analytics/xirr.ts
- •server/analytics/fees.ts
•
Editing:
- •docs/xirr.truth-cases.json
- •docs/fees.truth-cases.json
•Cross-checking against Excel/Sheets XIRR or simple fee math.

XIRR

•Use irregular cash-flow IRR with proper date handling.
•
Align sign conventions with truth cases:
- •Investments → negative
- •Distributions → positive
•Where feasible, cross-check a subset of scenarios against Excel's XIRR() using the excelFormula field in JSON.

Fees

•
Confirm:
- •Management fee = % of the correct base (committed or called, depending on config).
- •Fee timing matches the fund life / fee schedule.
•
Truth cases should include:
- •Simple "2% of commitment" scenarios.
- •Step-down and alternative-fee-basis examples if implemented.

Tests & Truth Cases

•
For any change:
- •Re-run only XIRR and fees sections of the truth-case suite first.
- •Then run the full suite.
•
If you update expectations:
- •Fix the JSON.
- •Document in docs/phase0-validation-report.md what changed and why.