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.