LedgerLoom Chapter 08.5 — Opening the Next Period

This bridge chapter connects Chapter 08 (closing) to Part III (operational cycles).

After you close the books for a period, you have a post-close trial balance where:

  • Temporary accounts (Revenue / Expenses / IncomeSummary) are zeroed

  • Permanent accounts (Assets / Liabilities / Equity) carry the ending balances forward

  • Retained earnings captures the period’s net income (via the close)

Chapter 08.5 shows the next story beat:

post-close → opening the next period (and proving continuity)

What you will build

You will generate a single Opening Balances entry dated on the first day of the next period that reproduces the permanent-account balances from Chapter 08’s post-close trial balance.

You will also emit proof artifacts that:

  • Reconcile post-close TB (Ch08) to opening TB (Ch08.5)

  • Confirm that Revenue/Expenses open at 0.00

  • Confirm RetainedEarnings continuity

How it works

  1. Compute Chapter 08 post-close trial balance (in-memory, deterministic).

  2. Convert each permanent-account balance into a debit or credit line, based on normal balance conventions (Assets are debit-normal; Liabilities/Equity are credit-normal).

  3. Compile the opening entry through the same engine, producing: - postings - opening trial balance - opening balance sheet

  4. Produce an explicit reconciliation against the Ch08 post-close trial balance.

How to run

From the project root:

make ll-ch085

Artifacts

This runner writes deterministic outputs to:

outputs/ledgerloom/ch085/

Key files:

  • trial_balance_post_close.csv — the Ch08 post-close TB (source-of-truth)

  • trial_balance_opening.csv — the opening TB for the next period

  • reconciliation_post_close_vs_opening.csv — per-account diffs (should all be 0.00)

  • retained_earnings_continuity.csv — focused proof line for retained earnings

  • invariants.json + manifest.json — engine invariants and artifact hashes

Next

Part III begins with Chapter 09 — Accounts Receivable lifecycle.