Expense Report Builder

What this skill does

Reads a list of receipts (CSV or JSON, with vendor, date, amount, currency, optional category) and builds an expense report with category totals, currency-converted line items, and a submission-ready packet.

Inputs

• receipts_path: CSV/JSON of receipts.
• report_period: ISO interval, e.g., 2026-04-01/2026-04-30.
• Optional home_currency: defaults USD.
• Optional policy_path: a YAML naming categories, per-day caps, and required-receipt amounts.
• Optional fx_rates: a CSV of date-to-rate; otherwise fetched.

Steps

1. Load receipts. Filter to those whose date falls inside report_period.
2. Categorize each: if category already populated, keep; else apply a vendor-to-category map (e.g., Uber/Lyft -> ground-transport, Marriott/Hilton -> lodging, Whole Foods -> groceries which is usually non-reimbursable).
3. Convert non-home-currency amounts to home_currency using fx_rates lookup keyed by date; if a date is missing, use the closest prior date.
4. Apply policy checks:
   • Receipt missing for amount above the required-receipt threshold -> flag.
   • Per-day total per category exceeds cap -> flag.
   • Disallowed merchant (alcohol vendor on a no-alcohol policy) -> flag.
5. Compute per-category totals and overall total.
6. Group by day for the time-ordered ledger.
7. Generate a markdown packet with: cover header (period, name, totals per category, grand total), itemized table (date, vendor, category, native amount, converted amount, note), and a "Policy Exceptions" section.
8. Generate a CSV in the format the user's expense system expects (configurable; default Concur-style columns).
9. Save both files.

Output

expenses-<period>.md (the packet) and expenses-<period>.csv (system import). Stdout prints the grand total and any policy exception count. Exit 1 if any blocker-level policy violation is unresolved.

Verification

Recompute the grand total from raw amounts converted with the fx rates and confirm match. For each policy-flagged item, re-read the policy file to ensure the violation is real (not a misconfigured cap). Spot-check three currency conversions against an external FX source to ensure the rate sheet is current.

Edge cases

• Missing FX rate for a non-trading day (weekend): use the most recent business-day rate and note the substitution.
• Tipping conventions vary by country: the receipt should already include tip; do not double-add.
• Personal portion of a mixed receipt (e.g., business dinner with a friend): require a personal_amount field and exclude.
• Multi-currency same trip with reimbursement in only one currency: the home currency total is canonical; native amounts are kept for audit.