feat: period-scoped P&L and as-of balance sheet; closes don't zero periods

The engine only had life-of-ledger P&L and balance sheet totals, so every
export labeled with a date range or as-of date (PDF, XLSX, CPA package)
printed all-time numbers under that label. Core now has:

- profit_and_loss_for_period(start, end, class?) and
  balance_sheet_as_of(as_of), each with a line per account
  (StatementLine: code, name, normal-side amount) and exact totals.
- Ledger::closing_entry_ids(). Period statements exclude closing entries.
  A close (Dr revenue / Cr expense / net to Retained Earnings, dated at
  period end) moves earnings; it doesn't earn or spend. Counting it made a
  closed period's P&L read as break-even, and made the cash flow show zero
  net income plus a fake "owner contribution" to Retained Earnings. The
  as-of balance sheet keeps closing entries: after a close the earnings
  belong in Retained Earnings, not current earnings.

Tests: tests/statements.rs, a two-month fixture with every expected number
computed by hand (Jan NI 1,700; Feb 880; balance sheets on four dates; a
closed January still reporting 1,700 and a cash flow with one financing
line). Mutation-checked: dropping the closing exclusion fails it (0 vs
1,700). Properties: period P&Ls partition a year at any split, and a
range's net income equals the change in current earnings across it, with
A = L + E on both dates.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MtYEaR6M6Ybdhm6X98BWNu

crates/ledger-core/src/ledger.rs

@@ -568,6 +568,16 @@ impl Ledger {
         self.periods.get(&id)
     }
 
+    /// Ids of every period-closing entry. Period statements (P&L, cash
+    /// flow) exclude them: a close moves earnings into retained earnings; it
+    /// earns and spends nothing, so counting it would zero out the period.
+    pub fn closing_entry_ids(&self) -> std::collections::BTreeSet<EntryId> {
+        self.periods
+            .values()
+            .filter_map(|p| p.closing_entry)
+            .collect()
+    }
+
     /// All periods, in creation order.
     pub fn list_periods(&self) -> Vec<&Period> {
         let mut ids: Vec<PeriodId> = self.periods.keys().copied().collect();

crates/ledger-core/src/lib.rs

@@ -45,6 +45,7 @@ pub use money::{Currency, Money};
 pub use payroll::{PayrollLine, PayrollRun, PayrollRunId};
 pub use periods::{Period, PeriodId, PeriodStatus};
 pub use reports::{
-    BalanceSheet, CashFlowLine, CashFlowParams, CashFlowStatement, ClassProfitAndLoss,
+    BalanceSheet, BalanceSheetStatement, CashFlowLine, CashFlowParams, CashFlowStatement,
-    ProfitAndLoss, TrialBalance, TrialBalanceLine, cash_flow,
+    ClassProfitAndLoss, ProfitAndLoss, ProfitAndLossStatement, StatementLine, TrialBalance,
+    TrialBalanceLine, balance_sheet_as_of, cash_flow, profit_and_loss_for_period,
 };

crates/ledger-core/src/reports.rs

@@ -4,10 +4,11 @@
 //! (`docs/oracle.md`) diffs: the same fixture books through two engines must
 //! produce byte-identical [`snapshot`] output.
 
-use crate::{AccountType, Class, ClassId, JournalLine, Ledger, LedgerError};
+use crate::{AccountType, Class, ClassId, JournalEntry, JournalLine, Ledger, LedgerError};
+use chrono::NaiveDate;
 use rust_decimal::Decimal;
 use serde::{Deserialize, Serialize};
-use std::collections::BTreeSet;
+use std::collections::{BTreeMap, BTreeSet};
 
 /// One line of a trial balance.
 #[derive(Clone, Debug, Serialize, Deserialize)]
@@ -78,8 +79,8 @@ pub fn trial_balance(ledger: &Ledger) -> TrialBalance {
     }
 }
 
-/// Profit and loss: revenue and expenses for the life of the ledger.
+/// Profit and loss: revenue and expenses for the life of the ledger. For a
-/// (Period filtering is R-FUTURE work; see `docs/requirements.md` R-7.)
+/// date range, with a line per account, use [`profit_and_loss_for_period`].
 #[derive(Clone, Debug, Serialize, Deserialize)]
 pub struct ProfitAndLoss {
     /// Total revenue (credit-normal balances, reported positive).
@@ -265,6 +266,200 @@ pub fn balance_sheet(ledger: &Ledger) -> Result<BalanceSheet, LedgerError> {
     })
 }
 
+/// One account's line on a financial statement.
+#[derive(Clone, Debug, Serialize, Deserialize, PartialEq)]
+pub struct StatementLine {
+    /// Account code, e.g. `"6000"`.
+    pub code: String,
+    /// Account name.
+    pub name: String,
+    /// Amount on the account's normal side: positive is a normal balance
+    /// (or movement), negative a contra one.
+    pub amount: Decimal,
+}
+
+/// Profit and loss for a date range, with a line per account.
+#[derive(Clone, Debug, Serialize, Deserialize)]
+pub struct ProfitAndLossStatement {
+    /// First date, inclusive.
+    pub start: NaiveDate,
+    /// Last date, inclusive.
+    pub end: NaiveDate,
+    /// Revenue accounts with movement in the range, by code.
+    pub revenue: Vec<StatementLine>,
+    /// Expense accounts with movement in the range, by code.
+    pub expenses: Vec<StatementLine>,
+    /// Sum of the revenue lines.
+    pub total_revenue: Decimal,
+    /// Sum of the expense lines.
+    pub total_expenses: Decimal,
+}
+
+impl ProfitAndLossStatement {
+    /// Revenue minus expenses. Positive is profit.
+    pub fn net_income(&self) -> Decimal {
+        self.total_revenue - self.total_expenses
+    }
+}
+
+/// Balance sheet as of a date, with a line per account.
+#[derive(Clone, Debug, Serialize, Deserialize)]
+pub struct BalanceSheetStatement {
+    /// The as-of date, inclusive.
+    pub as_of: NaiveDate,
+    /// Asset accounts with a balance, by code.
+    pub assets: Vec<StatementLine>,
+    /// Liability accounts with a balance, by code.
+    pub liabilities: Vec<StatementLine>,
+    /// Equity accounts with a balance, by code (current earnings excluded).
+    pub equity: Vec<StatementLine>,
+    /// Revenue minus expenses through `as_of` not yet closed to retained
+    /// earnings. Shown as its own equity line.
+    pub current_earnings: Decimal,
+    /// Sum of the asset lines.
+    pub total_assets: Decimal,
+    /// Sum of the liability lines.
+    pub total_liabilities: Decimal,
+    /// Sum of the equity lines plus current earnings.
+    pub total_equity: Decimal,
+}
+
+impl BalanceSheetStatement {
+    /// The accounting equation: assets == liabilities + equity, exactly.
+    pub fn balanced(&self) -> bool {
+        self.total_assets == self.total_liabilities + self.total_equity
+    }
+}
+
+/// Normal-side amount per account over the posted lines accepted by
+/// `include(entry, line)`, as statement lines keyed (and so sorted) by
+/// code, skipping placeholders and zero amounts.
+fn statement_lines(
+    ledger: &Ledger,
+    include: &dyn Fn(&JournalEntry, &JournalLine) -> bool,
+) -> Result<BTreeMap<String, (AccountType, StatementLine)>, LedgerError> {
+    let mut movement: BTreeMap<crate::AccountId, Decimal> = BTreeMap::new();
+    for entry in ledger.posted_entries() {
+        for line in entry.lines() {
+            if !include(entry, line) {
+                continue;
+            }
+            let signed = match line.side {
+                crate::Side::Debit => line.amount.amount,
+                crate::Side::Credit => -line.amount.amount,
+            };
+            *movement.entry(line.account).or_default() += signed;
+        }
+    }
+    let mut out = BTreeMap::new();
+    for (id, m) in movement {
+        let account = ledger
+            .chart()
+            .get(id)
+            .ok_or(LedgerError::UnknownAccount(id))?;
+        if account.placeholder || m.is_zero() {
+            continue;
+        }
+        let amount = match account.account_type.normal_side() {
+            crate::Side::Debit => m,
+            crate::Side::Credit => -m,
+        };
+        out.insert(
+            account.code.clone(),
+            (
+                account.account_type,
+                StatementLine {
+                    code: account.code.clone(),
+                    name: account.name.clone(),
+                    amount,
+                },
+            ),
+        );
+    }
+    Ok(out)
+}
+
+/// Profit and loss for `[start, end]`, optionally for one class (`None`
+/// counts every line). Closing entries are excluded: they move a period's
+/// earnings into retained earnings, so counting them would report a closed
+/// period as breaking even.
+pub fn profit_and_loss_for_period(
+    ledger: &Ledger,
+    start: NaiveDate,
+    end: NaiveDate,
+    class_id: Option<ClassId>,
+) -> Result<ProfitAndLossStatement, LedgerError> {
+    if end < start {
+        return Err(LedgerError::InvalidDateRange {
+            start: start.to_string(),
+            end: end.to_string(),
+        });
+    }
+    let closings = ledger.closing_entry_ids();
+    let lines = statement_lines(ledger, &|entry, line| {
+        entry.date() >= start
+            && entry.date() <= end
+            && !closings.contains(&entry.id())
+            && class_id.is_none_or(|c| line.class_id == Some(c))
+    })?;
+    let mut revenue = Vec::new();
+    let mut expenses = Vec::new();
+    for (typ, line) in lines.into_values() {
+        match typ {
+            AccountType::Revenue => revenue.push(line),
+            AccountType::Expense => expenses.push(line),
+            _ => {}
+        }
+    }
+    let total_revenue = revenue.iter().map(|l| l.amount).sum();
+    let total_expenses = expenses.iter().map(|l| l.amount).sum();
+    Ok(ProfitAndLossStatement {
+        start,
+        end,
+        revenue,
+        expenses,
+        total_revenue,
+        total_expenses,
+    })
+}
+
+/// Balance sheet as of `as_of`: every posted entry dated on or before it.
+/// Revenue and expense not yet closed to retained earnings appear as
+/// current earnings inside equity, so the accounting equation holds on
+/// every date, before and after closes.
+pub fn balance_sheet_as_of(
+    ledger: &Ledger,
+    as_of: NaiveDate,
+) -> Result<BalanceSheetStatement, LedgerError> {
+    let lines = statement_lines(ledger, &|entry, _| entry.date() <= as_of)?;
+    let mut assets = Vec::new();
+    let mut liabilities = Vec::new();
+    let mut equity = Vec::new();
+    let mut current_earnings = Decimal::ZERO;
+    for (typ, line) in lines.into_values() {
+        match typ {
+            AccountType::Asset => assets.push(line),
+            AccountType::Liability => liabilities.push(line),
+            AccountType::Equity => equity.push(line),
+            AccountType::Revenue => current_earnings += line.amount,
+            AccountType::Expense => current_earnings -= line.amount,
+        }
+    }
+    let total_assets = assets.iter().map(|l| l.amount).sum();
+    let total_liabilities = liabilities.iter().map(|l| l.amount).sum();
+    let total_equity = equity.iter().map(|l| l.amount).sum::<Decimal>() + current_earnings;
+    Ok(BalanceSheetStatement {
+        as_of,
+        assets,
+        liabilities,
+        equity,
+        current_earnings,
+        total_assets,
+        total_liabilities,
+        total_equity,
+    })
+}
+
 /// Render the three core reports as canonical JSON for oracle diffing.
 ///
 /// Amounts are decimal strings (never floats, never locale-formatted), lines
@@ -406,11 +601,14 @@ pub fn cash_flow(
     let financing_set: HashSet<crate::AccountId> =
         params.financing_accounts.iter().copied().collect();
 
-    // Movement helpers: debits minus credits over a date predicate.
+    // Movement helpers: debits minus credits over a date predicate. Closing
+    // entries are skipped: a close moves earnings into retained earnings,
+    // which is neither net income nor an owner flow.
+    let closings = ledger.closing_entry_ids();
     let movement_where = |account: crate::AccountId, pred: &dyn Fn(chrono::NaiveDate) -> bool| {
         let mut total = Decimal::ZERO;
         for entry in ledger.posted_entries() {
-            if !pred(entry.date()) {
+            if !pred(entry.date()) || closings.contains(&entry.id()) {
                 continue;
             }
             for line in entry.lines() {

crates/ledger-core/tests/properties.rs

@@ -9,7 +9,10 @@ use chrono::NaiveDate;
 use ledger_core::{
     AccountType, Currency, Ledger, Money, NewAsset, Side, accumulated_depreciation, book_value,
     depreciation_schedule,
-    reports::{balance_sheet, trial_balance},
+    reports::{
+        balance_sheet, balance_sheet_as_of, profit_and_loss, profit_and_loss_for_period,
+        trial_balance,
+    },
 };
 use proptest::prelude::*;
 use rust_decimal::Decimal;
@@ -136,6 +139,52 @@ proptest! {
         prop_assert_eq!(bs.assets, bs.liabilities + bs.equity);
     }
 
+    /// Period P&Ls partition the year: split anywhere, the two halves sum
+    /// to the whole, and the whole is the life-of-ledger P&L.
+    #[test]
+    fn prop_period_pnl_partitions((chart, entries) in arb_ops(), split in 0u32..365) {
+        let (ledger, _) = build_ledger(&chart, &entries);
+        let jan1 = NaiveDate::from_ymd_opt(2026, 1, 1).unwrap();
+        let dec31 = NaiveDate::from_ymd_opt(2026, 12, 31).unwrap();
+        let cut = jan1 + chrono::Days::new(split as u64);
+        let first = profit_and_loss_for_period(&ledger, jan1, cut, None).unwrap();
+        let rest = if cut < dec31 {
+            Some(profit_and_loss_for_period(&ledger, cut.succ_opt().unwrap(), dec31, None).unwrap())
+        } else {
+            None
+        };
+        let whole = profit_and_loss_for_period(&ledger, jan1, dec31, None).unwrap();
+        let (r2, e2) = rest.map_or((Decimal::ZERO, Decimal::ZERO), |p| (p.total_revenue, p.total_expenses));
+        prop_assert_eq!(first.total_revenue + r2, whole.total_revenue);
+        prop_assert_eq!(first.total_expenses + e2, whole.total_expenses);
+        let all = profit_and_loss(&ledger).unwrap();
+        prop_assert_eq!((whole.total_revenue, whole.total_expenses), (all.revenue, all.expenses));
+    }
+
+    /// The accounting equation holds as of every date, and a period's net
+    /// income is exactly the change in current earnings across it.
+    #[test]
+    fn prop_balance_sheet_as_of_balances((chart, entries) in arb_ops(), a in 0u32..365, b in 0u32..365) {
+        let (ledger, _) = build_ledger(&chart, &entries);
+        let jan1 = NaiveDate::from_ymd_opt(2026, 1, 1).unwrap();
+        let (lo, hi) = (a.min(b), a.max(b));
+        let start = jan1 + chrono::Days::new(lo as u64);
+        let end = jan1 + chrono::Days::new(hi as u64);
+        let before = balance_sheet_as_of(&ledger, start.pred_opt().unwrap()).unwrap();
+        let after = balance_sheet_as_of(&ledger, end).unwrap();
+        prop_assert!(before.balanced());
+        prop_assert!(after.balanced());
+        let pnl = profit_and_loss_for_period(&ledger, start, end, None).unwrap();
+        prop_assert_eq!(after.current_earnings - before.current_earnings, pnl.net_income());
+        // Past the last entry, as-of agrees with the life-of-ledger sheet.
+        let all = balance_sheet(&ledger).unwrap();
+        let last = balance_sheet_as_of(&ledger, NaiveDate::from_ymd_opt(2026, 12, 31).unwrap()).unwrap();
+        prop_assert_eq!(
+            (last.total_assets, last.total_liabilities, last.total_equity),
+            (all.assets, all.liabilities, all.equity)
+        );
+    }
+
     /// Every posted entry balances on its own, exactly.
     #[test]
     fn prop_posted_entries_balance((chart, entries) in arb_ops()) {

crates/ledger-core/tests/statements.rs

@@ -0,0 +1,223 @@
+//! Period-scoped financial statements: profit and loss for a date range and
+//! the balance sheet as of a date, line per account.
+//!
+//! Every expected number below is computed by hand from the entries, not
+//! read off the engine. The fixture is two months of a small company:
+//!
+//! | date   | entry                         | Dr            | Cr            |
+//! |--------|-------------------------------|---------------|---------------|
+//! | Jan 2  | owner contributes 10,000      | 1000 Cash     | 3000 Capital  |
+//! | Jan 15 | client pays 2,500             | 1000 Cash     | 4000 Revenue  |
+//! | Jan 20 | rent 800                      | 6100 Rent     | 1000 Cash     |
+//! | Feb 3  | software 120 on the card      | 6000 Software | 2000 Card     |
+//! | Feb 10 | client pays 1,000             | 1000 Cash     | 4000 Revenue  |
+//! | Feb 25 | pay the card 120              | 2000 Card     | 1000 Cash     |
+
+use chrono::NaiveDate;
+use ledger_core::reports::{
+    balance_sheet, balance_sheet_as_of, profit_and_loss, profit_and_loss_for_period,
+};
+use ledger_core::{
+    AccountId, AccountType, CashFlowParams, ClassId, Currency, Ledger, Money, Side, StatementLine,
+    cash_flow,
+};
+use rust_decimal::Decimal;
+
+fn d(m: u32, day: u32) -> NaiveDate {
+    NaiveDate::from_ymd_opt(2026, m, day).unwrap()
+}
+
+fn usd(n: i64) -> Money {
+    Money::new(Decimal::from(n), Currency::USD)
+}
+
+fn dec(n: i64) -> Decimal {
+    Decimal::from(n)
+}
+
+struct Books {
+    ledger: Ledger,
+    cash: AccountId,
+    software_class: ClassId,
+}
+
+fn post(ledger: &mut Ledger, date: NaiveDate, desc: &str, dr: AccountId, cr: AccountId, n: i64) {
+    let e = ledger.create_entry(date, desc);
+    ledger.add_line(e, dr, Side::Debit, usd(n)).unwrap();
+    ledger.add_line(e, cr, Side::Credit, usd(n)).unwrap();
+    ledger.post_entry(e).unwrap();
+}
+
+/// The fixture. With `close_january`, January is closed before any February
+/// entry exists (the close sweeps every revenue and expense balance).
+fn books(close_january: bool) -> Books {
+    let mut l = Ledger::new(Currency::USD);
+    let cash = l
+        .add_account("1000", "Cash", AccountType::Asset, None, false)
+        .unwrap();
+    let card = l
+        .add_account("2000", "Card", AccountType::Liability, None, false)
+        .unwrap();
+    let capital = l
+        .add_account("3000", "Capital", AccountType::Equity, None, false)
+        .unwrap();
+    let revenue = l
+        .add_account("4000", "Revenue", AccountType::Revenue, None, false)
+        .unwrap();
+    let software = l
+        .add_account("6000", "Software", AccountType::Expense, None, false)
+        .unwrap();
+    let rent = l
+        .add_account("6100", "Rent", AccountType::Expense, None, false)
+        .unwrap();
+    let software_class = l.add_class("Apps").unwrap();
+
+    post(&mut l, d(1, 2), "Owner contribution", cash, capital, 10_000);
+    post(&mut l, d(1, 15), "Client payment", cash, revenue, 2_500);
+    post(&mut l, d(1, 20), "Rent", rent, cash, 800);
+    if close_january {
+        let jan = l.create_period("2026-01", d(1, 1), d(1, 31)).unwrap();
+        l.close_period(jan).unwrap();
+    }
+    // Software on the card, tagged to the Apps class.
+    let e = l.create_entry(d(2, 3), "Software");
+    l.add_line(e, software, Side::Debit, usd(120)).unwrap();
+    l.add_line(e, card, Side::Credit, usd(120)).unwrap();
+    l.set_line_class(e, 0, Some(software_class)).unwrap();
+    l.post_entry(e).unwrap();
+    post(&mut l, d(2, 10), "Client payment", cash, revenue, 1_000);
+    post(&mut l, d(2, 25), "Pay card", card, cash, 120);
+    Books {
+        ledger: l,
+        cash,
+        software_class,
+    }
+}
+
+fn line(code: &str, name: &str, n: i64) -> StatementLine {
+    StatementLine {
+        code: code.to_string(),
+        name: name.to_string(),
+        amount: dec(n),
+    }
+}
+
+#[test]
+fn profit_and_loss_is_scoped_to_the_period() {
+    let b = books(false);
+    let jan = profit_and_loss_for_period(&b.ledger, d(1, 1), d(1, 31), None).unwrap();
+    assert_eq!(jan.revenue, vec![line("4000", "Revenue", 2_500)]);
+    assert_eq!(jan.expenses, vec![line("6100", "Rent", 800)]);
+    assert_eq!(jan.net_income(), dec(1_700));
+
+    let feb = profit_and_loss_for_period(&b.ledger, d(2, 1), d(2, 28), None).unwrap();
+    assert_eq!(feb.revenue, vec![line("4000", "Revenue", 1_000)]);
+    assert_eq!(feb.expenses, vec![line("6000", "Software", 120)]);
+    assert_eq!(feb.net_income(), dec(880));
+
+    // Both months: 3,500 revenue, 920 expenses, lines sorted by code.
+    let both = profit_and_loss_for_period(&b.ledger, d(1, 1), d(2, 28), None).unwrap();
+    assert_eq!(
+        both.expenses,
+        vec![line("6000", "Software", 120), line("6100", "Rent", 800)]
+    );
+    assert_eq!(
+        (both.total_revenue, both.total_expenses),
+        (dec(3_500), dec(920))
+    );
+    // ... which is the life-of-ledger P&L, because nothing is outside it.
+    let all = profit_and_loss(&b.ledger).unwrap();
+    assert_eq!((all.revenue, all.expenses), (dec(3_500), dec(920)));
+
+    // One class: only the tagged software line.
+    let apps =
+        profit_and_loss_for_period(&b.ledger, d(1, 1), d(12, 31), Some(b.software_class)).unwrap();
+    assert!(apps.revenue.is_empty());
+    assert_eq!(apps.expenses, vec![line("6000", "Software", 120)]);
+
+    // A backwards range is rejected, not silently empty.
+    assert!(profit_and_loss_for_period(&b.ledger, d(2, 1), d(1, 1), None).is_err());
+}
+
+#[test]
+fn balance_sheet_is_as_of_the_date() {
+    let b = books(false);
+    // Before anything happened: empty and balanced.
+    let start = balance_sheet_as_of(&b.ledger, d(1, 1)).unwrap();
+    assert!(start.assets.is_empty() && start.equity.is_empty());
+    assert!(start.balanced());
+
+    // Jan 31: cash 10,000 + 2,500 − 800 = 11,700; equity 10,000 + 1,700.
+    let jan = balance_sheet_as_of(&b.ledger, d(1, 31)).unwrap();
+    assert_eq!(jan.assets, vec![line("1000", "Cash", 11_700)]);
+    assert!(jan.liabilities.is_empty());
+    assert_eq!(jan.equity, vec![line("3000", "Capital", 10_000)]);
+    assert_eq!(jan.current_earnings, dec(1_700));
+    assert_eq!(jan.total_equity, dec(11_700));
+    assert!(jan.balanced());
+
+    // Feb 15: cash 12,700; the card owes 120; earnings 1,700 + 880.
+    let mid = balance_sheet_as_of(&b.ledger, d(2, 15)).unwrap();
+    assert_eq!(mid.total_assets, dec(12_700));
+    assert_eq!(mid.liabilities, vec![line("2000", "Card", 120)]);
+    assert_eq!(mid.current_earnings, dec(2_580));
+    assert_eq!(mid.total_liabilities + mid.total_equity, dec(12_700));
+
+    // Feb 28: card paid off, so it drops off the statement.
+    let end = balance_sheet_as_of(&b.ledger, d(2, 28)).unwrap();
+    assert_eq!(end.total_assets, dec(12_580));
+    assert!(end.liabilities.is_empty());
+    assert!(end.balanced());
+    // ... and agrees with the life-of-ledger balance sheet.
+    let all = balance_sheet(&b.ledger).unwrap();
+    assert_eq!(
+        (all.assets, all.liabilities, all.equity),
+        (end.total_assets, end.total_liabilities, end.total_equity)
+    );
+}
+
+#[test]
+fn a_closed_period_still_reports_its_earnings() {
+    let b = books(true);
+    // The close posted Dr 4000 2,500 / Cr 6100 800 / Cr 3999 1,700 on Jan
+    // 31. The January P&L must not count it: January earned 1,700.
+    let jan = profit_and_loss_for_period(&b.ledger, d(1, 1), d(1, 31), None).unwrap();
+    assert_eq!(jan.net_income(), dec(1_700));
+    assert_eq!(jan.revenue, vec![line("4000", "Revenue", 2_500)]);
+    let feb = profit_and_loss_for_period(&b.ledger, d(2, 1), d(2, 28), None).unwrap();
+    assert_eq!(feb.net_income(), dec(880));
+
+    // After the close, January's earnings sit in retained earnings, not in
+    // current earnings; February's are current.
+    let jan_bs = balance_sheet_as_of(&b.ledger, d(1, 31)).unwrap();
+    assert_eq!(
+        jan_bs.equity,
+        vec![
+            line("3000", "Capital", 10_000),
+            line("3999", "Retained Earnings", 1_700)
+        ]
+    );
+    assert_eq!(jan_bs.current_earnings, Decimal::ZERO);
+    assert!(jan_bs.balanced());
+    let feb_bs = balance_sheet_as_of(&b.ledger, d(2, 28)).unwrap();
+    assert_eq!(feb_bs.current_earnings, dec(880));
+    assert_eq!(feb_bs.total_equity, dec(12_580));
+    assert!(feb_bs.balanced());
+
+    // The cash flow for January: net income 1,700, and the only financing
+    // flow is the owner's 10,000. The close is not an owner contribution.
+    let cf = cash_flow(
+        &b.ledger,
+        &CashFlowParams {
+            start: d(1, 1),
+            end: d(1, 31),
+            cash_accounts: vec![b.cash],
+            financing_accounts: vec![],
+        },
+    )
+    .unwrap();
+    assert_eq!(cf.net_income, dec(1_700));
+    assert_eq!(cf.financing.len(), 1);
+    assert_eq!(cf.cash_from_financing, dec(10_000));
+    assert_eq!(cf.net_change_in_cash, dec(11_700));
+}

docs/parity.md

@@ -19,6 +19,8 @@ No other statuses.
 | Trial balance | Reports → Trial Balance | done | golden-covered |
 | Balance sheet (A = L + E) | Reports → Balance Sheet | done | current earnings folded in pre-close; golden-covered |
 | Profit & loss | Reports → Income Statement | done | golden-covered |
+| P&L for a date range, line per account (closing entries excluded) | Reports → Income Statement (custom dates) | partial | hand-verified fixture + property tests; no golden file yet |
+| Balance sheet as of a date, line per account | Reports → Balance Sheet (as of) | partial | hand-verified fixture + property tests; no golden file yet |
 | Reversing entries | Reverse transaction | done | linked via `reversal_of` |
 | Canonical report snapshots (JSON) | — (our oracle format) | done | `reports::snapshot` |
 | Fixed-asset register + straight-line depreciation | Fixed Asset register | done | `assets.rs`; golden-covered schedule; idempotent runs; disposal with gain/loss |

docs/requirements.md

@@ -34,10 +34,19 @@ requirement conflict, the requirement wins.
   total credits (the `balanced()` check).
 - **R-8 — Balance sheet.** Assets, liabilities, equity grouped by account
   type. The accounting equation holds exactly: assets = liabilities + equity.
-  Because period close (R-FUTURE-2) doesn't exist yet, current earnings (net
+  Current earnings (revenue minus expenses not yet closed to retained
-  income to date) are folded into equity so the equation holds on a live book.
+  earnings) are folded into equity so the equation holds on a live book.
-- **R-9 — Profit and loss.** Revenue and expenses for the life of the ledger,
+  `balance_sheet_as_of` gives the statement as of any date, a line per
-  with net income. Period filtering arrives with R-FUTURE-2.
+  account, counting every entry dated on or before it (closing entries
+  included: after a close the earnings sit in retained earnings).
+- **R-9 — Profit and loss.** Revenue and expenses with net income.
+  `profit_and_loss_for_period` scopes it to a date range (optionally one
+  class), a line per account, and **excludes closing entries**: a close moves
+  earnings into retained earnings and must not make a closed period read as
+  break-even. The cash flow statement excludes closing entries for the same
+  reason. Period P&Ls partition: split a range anywhere and the halves sum
+  to the whole, and a range's net income equals the change in current
+  earnings across it (property-tested).
 - **R-10 — Canonical snapshots.** `reports::snapshot()` renders the three
   core reports as deterministic JSON (decimal strings, sorted lines, fixed
   keys). Two engines fed the same books must produce identical output. This