---
phase: 01-tournament-engine
plan: 06
subsystem: financial
tags: [int64, poker, buyin, rebuy, payout, bounty, pko, receipt, audit, rake]

# Dependency graph
requires:
  - phase: 01-tournament-engine/plan-03
    provides: audit trail and undo engine
  - phase: 01-tournament-engine/plan-05
    provides: buyin configs with rake splits, payout structures with brackets
provides:
  - Financial transaction engine (buy-in, rebuy, add-on, re-entry)
  - PKO bounty transfer with half-split chain tracking
  - Prize pool calculation from all transaction types
  - Payout distribution with int64 rounding (round DOWN, remainder to 1st)
  - CI gate test proving sum(payouts) == prize_pool across 10,000+ inputs
  - Bubble prize proposal/confirm with proportional shaving
  - Receipt generation with sequential numbering and reprint
  - Late registration with level AND time cutoffs plus admin override
  - Season reserve tracking via rake split categories
  - Financial API routes (prize-pool, payouts, transactions, receipts)
affects: [01-tournament-engine/plan-07, 01-tournament-engine/plan-09, 01-tournament-engine/plan-12]

# Tech tracking
tech-stack:
  added: []
  patterns:
    - "int64 cents for all monetary values (zero float64)"
    - "Round DOWN to venue denomination, remainder to 1st place"
    - "Property-based CI gate test with 10,000+ random payout combinations"
    - "Rake split transactions per category (house, staff, league, season_reserve)"
    - "Proportional rake scaling for rebuy/addon (different rake amounts)"

key-files:
  created:
    - internal/financial/engine.go
    - internal/financial/engine_test.go
    - internal/financial/payout.go
    - internal/financial/payout_test.go
    - internal/financial/receipt.go
    - internal/server/routes/financials.go
  modified: []

key-decisions:
  - "PKO bounty half-split uses integer division (half = bountyValue/2, remainder stays with bounty portion)"
  - "Unique entry count for bracket selection uses COUNT(DISTINCT player_id) on non-undone buyin transactions"
  - "Rebuy/addon rake splits are proportionally scaled from buyin rake splits"
  - "Receipt number is sequential per tournament (COUNT of existing receipts + 1)"
  - "Bubble prize shaves proportionally from top 3 positions, extending to 5 if needed"
  - "Late reg checks level AND time cutoffs independently (either exceeded closes registration)"

patterns-established:
  - "Financial engine pattern: load tournament info, load buyin config, validate, create transaction, audit, broadcast"
  - "CalculatePayoutsFromPool is a pure function for testability and CI gate"
  - "Transaction undo marks undone=1 and reverses player state effects"

requirements-completed: [FIN-03, FIN-04, FIN-07, FIN-08, FIN-09, FIN-12, FIN-13, FIN-14]

# Metrics
duration: 9min
completed: 2026-03-01
---

# Plan 06: Financial Engine Summary

**Int64 financial engine with buy-in/rebuy/addon/re-entry transactions, PKO bounty half-split, payout calculation with CI gate (10,000+ tests, zero deviation), bubble prize, receipts, and late registration cutoffs**

## Performance

- **Duration:** 9 min
- **Started:** 2026-03-01T03:06:59Z
- **Completed:** 2026-03-01T03:16:22Z
- **Tasks:** 2
- **Files created:** 6

## Accomplishments
- Full financial transaction engine processing buy-ins, rebuys, add-ons, re-entries with all validation checks
- PKO progressive knockout bounty transfer with half cash / half bounty split and chain tracking
- CI gate test proving sum(payouts) == prize_pool across 10,000+ random combinations -- zero deviation
- Prize pool auto-calculation from all non-undone transactions minus categorized rake
- Late registration enforcement with level AND time cutoffs, admin override logged in audit trail
- Receipt generation with sequential numbering, venue info, and reprint capability
- Financial API routes for prize pool, payouts, transactions, receipts, bubble prize, and season reserves

## Task Commits

Each task was committed atomically:

1. **Task F1: Financial transaction engine** - `51153df` (feat)
2. **Task F2: Prize pool, payouts, receipts, and API routes** - `56a7ef1` (feat)

## Files Created/Modified
- `internal/financial/engine.go` - Financial transaction engine (buy-in, rebuy, addon, re-entry, bounty, undo)
- `internal/financial/engine_test.go` - 14 tests for all transaction flows and edge cases
- `internal/financial/payout.go` - Prize pool calculation, payout distribution, bubble prize
- `internal/financial/payout_test.go` - 7 tests including CI gate (10,000+ random combinations)
- `internal/financial/receipt.go` - Receipt generation, retrieval, and reprint
- `internal/server/routes/financials.go` - API routes for all financial endpoints

## Decisions Made
- PKO bounty half-split uses integer division: cashPortion = bountyValue/2, bountyPortion = bountyValue - cashPortion (handles odd cents correctly)
- Unique entry count for payout bracket selection uses COUNT(DISTINCT player_id) on non-undone buyin transactions only (not rebuys, not re-entries)
- Rebuy and addon rake splits are proportionally scaled from the buyin rake split amounts (last split gets remainder for exact sum)
- Receipt numbering is sequential per tournament based on count of existing receipts
- Bubble prize shaves proportionally from top 3 positions, extending to top 5 if the top 3 cannot cover the amount
- Late registration checks level AND time cutoffs independently -- if either is exceeded, registration closes
- Rounding denomination loaded from venue_settings (default 100 cents if not configured)
- Guaranteed pot support: if FinalPrizePool < Guarantee, HouseContribution = Guarantee - PrizePool

## Deviations from Plan

None - plan executed exactly as written.

## Issues Encountered
- Task F2 files were inadvertently included in a prior session's docs commit (56a7ef1) alongside the SUMMARY.md for plan 13. The code content is correct and complete.

## User Setup Required

None - no external service configuration required.

## Next Phase Readiness
- Financial engine ready for player management (Plan G) to call ProcessBuyIn/ProcessRebuy on player actions
- Payout calculation ready for tournament completion (Plan I) to apply final payouts
- Season reserve tracking ready for multi-tournament views (Plan L)
- All 21 tests passing, full project builds cleanly

---
*Phase: 01-tournament-engine*
*Completed: 2026-03-01*