P3: depreciation straight-line by days through the final month, schedules by day (defects 22, 9, D-37)

The final month takes what the months before leave, spread over its days;
a disposed asset stops on its disposal day. A skipped month is caught up
in the month the run is made; a reversed run un-posts its month. New
schedules spread by day; equal-months schedules must start on the 1st.
Amounts round to the currency's own minor unit. Kani and Lean proofs; an
exhaustive search over runs, reversals and disposals.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01T3gXMVt7XJPi6ens1or9Dj

examples/depreciation-reversal-before-its-run-is-refused.toml

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+id = "depreciation-reversal-before-its-run-is-refused"
+title = "A depreciation run can't be reversed on a day before its own"
+rule = "A correction comes after what it corrects: a depreciation run, or a reversal of one, can't be reversed on a day before its own. A run of March reversed on Jan 31 would leave January and February with negative depreciation."
+status = "AUTHORITY"
+sources = ["Pacioli 1494, ch. 31"]
+tags = ["depreciation", "reversal", "refusal", "p3-defect-22"]
+
+[setup]
+currency = "USD"
+fiscal_year_start = "01-01"
+basis = "accrual"
+rounding = "half-away-from-zero"
+
+[[setup.accounts]]
+code = "1000"
+name = "Bank"
+type = "asset"
+
+[[setup.accounts]]
+code = "1500"
+name = "Equipment"
+type = "asset"
+
+[[setup.accounts]]
+code = "1510"
+name = "Accumulated Depreciation"
+type = "asset"
+
+[[setup.accounts]]
+code = "3000"
+name = "Capital"
+type = "equity"
+
+[[setup.accounts]]
+code = "6200"
+name = "Depreciation Expense"
+type = "expense"
+
+[[setup.accounts]]
+code = "7100"
+name = "Gain or Loss on Disposal"
+type = "revenue"
+
+# Asset X: 12,000.00, no salvage, 12 months from 2026-01-01 (1,000.00 a
+# month; December the final month).
+[[setup.assets]]
+id = "X"
+description = "Asset X"
+cost = "12000.00"
+salvage = "0.00"
+life_months = 12
+in_service = "2026-01-01"
+method = "straight_line"
+cost_account = "1500"
+accumulated_account = "1510"
+expense_account = "6200"
+
+[[events]]
+date = "2026-01-01"
+description = "Capital"
+lines = [
+  { account = "1000", side = "debit", amount = "12000.00" },
+  { account = "3000", side = "credit", amount = "12000.00" },
+]
+
+[[events]]
+date = "2026-01-01"
+description = "Bought asset X"
+lines = [
+  { account = "1500", side = "debit", amount = "12000.00" },
+  { account = "1000", side = "credit", amount = "12000.00" },
+]
+
+[[events]]
+run_depreciation = { asset = "X", period = "2026-01" }
+
+[[events]]
+run_depreciation = { asset = "X", period = "2026-02" }
+
+[[events]]
+run_depreciation = { asset = "X", period = "2026-03" }
+
+# March's run (dated Mar 31) reversed on Feb 10: refused, naming its date.
+[[events]]
+date = "2026-02-10"
+description = "Reverse event 5"
+reverses = 5
+refused = "entry_irreversible"
+
+# On its own day it is taken.
+[[events]]
+date = "2026-03-31"
+description = "Reverse event 5"
+reverses = 5
+
+# Hand check (worked without the code): January and February carry
+# 2,000.00 at February's end, never 1,000.00 (with March's 1,000.00 taken
+# away on Feb 10); March's end carries 2,000.00 (its run and its reversal
+# both dated Mar 31).
+[[expect]]
+query = "balances"
+as_of = "2026-02-28"
+
+[expect.values]
+"1510" = "-2000.00"
+"6200" = "2000.00"
+
+[[expect]]
+query = "balances"
+as_of = "2026-03-31"
+
+[expect.values]
+"1510" = "-2000.00"
+"6200" = "2000.00"