Edition 006 · interactive demo

Month-end used to be a weekend. Now it's a button.

The month-end pack is where finance credibility lives — and where weekends go to die: the year grid, the benchmark rows, the attribution table, the capital-flow line, all hand-assembled under deadline. This demo closes July for the (fictional) fund from Editions 002–004 in one click — then invites you to do the three things that break real month-ends: run it twice, fail the reconciliation, and drop funding into the middle of the month. Watch what a well-built close does in each case.

Honest-AI note. This page is deterministic engineering end to end — closes, grids, YTD compounding, attribution — and says so plainly; no live model call is made. In the production version the one AI touch is the monthly commentary draft (why the month did what it did), which a human edits and owns. Two rules here were paid for by real failures: the capital-flow row is signed (an abs() once turned funding into a phantom "withdrawal"), and the flow never enters P&L (funding is not performance).

Synthetic fund No live model Runs in your browser July lands on 002's NAV exactly

+S$500k funding lands 15 Jul break it: positions don't tie ✋

Close it clean first. Then close it again. Then break it.

July attribution foots to the P&L exactly

The gate, then the log

01Idempotent, or it isn't automation

A close you're afraid to re-run is a close you can't trust. Running it twice must refresh the same column with the same numbers — never append a duplicate, never double-count. Idempotency is what turns "the script" into "the system".

02Signed flows, never inside P&L

Contribution / (Withdrawal) is one signed row. An abs() here once converted funding into a phantom withdrawal in a real YTD. And the flow never touches performance — a fund that books funding as P&L is lying to its investors politely.

03The pack is hostage to the gate

Attribution must foot to the NAV move exactly; positions must tie; then and only then does anything leave the desk. A held pack costs a phone call. A wrong pack costs the thing you can't buy back.

Plain-language key (YTD compounding, attribution, capital flow, idempotent)

YTD compounding: Monthly returns chain multiplicatively — seven months of +1% is not +7%.
Attribution: The month's P&L split by position, summing to the NAV move exactly — no plug, no "other".
Capital flow: Money in or out of the fund (signed). Changes NAV; is not performance.
Idempotent: Safe to run again: the second run produces the same state, not a second copy.