Add four AASB 16 lessee functions to the Financial group

[ryanduguid]

Takes the library from 130 functions to 134. First coverage of an accounting standard rather than a tax rule.

Function	Purpose
oz.LeaseLiabilityλ(Payments, Rate, [InAdvance])	Present value of the lease payments not paid at the commencement date
oz.LeaseScheduleλ(Payments, Rate, [InAdvance])	Opening, payment, interest and closing rows for each period
oz.ROUScheduleλ(Cost, Periods)	Opening, depreciation and closing rows for the right-of-use asset
oz.LeaseRemeasureλ(RevisedPayments, Rate, CarryingLiability, CarryingROU, [InAdvance])	Revised liability, adjustment, revised asset, and the remainder taken to profit or loss

Rate is per period, not per year. InAdvance discounts each payment one period less, which is the timing most property leases use and the one most often set wrong.

How it was built

transform_from_upstream.py still cannot run without the uncommitted upstream workbook, so this is a postbuild pass over the committed ozzit.xlsx and src/, the same pattern as gst_help_text.py.

One spec per function generates both the published source and the stored defined name, rather than the two being written in parallel and left to drift. Every generated definition is round-tripped through verify_sources.py's own comparison before anything is written.

No worksheet is added. That is deliberate: it is what keeps all 20,228 cached values untouched.

Two bugs this turned up

sync_afe_store.py only ever wrote half the AFE store. The store holds module texts and a flat projectNames index. verify_afe.py has always gated both, but only the texts were synchronised, so adding any function failed that gate with the index short. Fixed here: a name still shipping keeps its place, a new one is filed after the last name from its own module, and a name that no longer ships is dropped. This would have blocked any future addition, not just this one.

The source comparison cannot see a missing marker. verify_sources.canonical strips _xlfn., _xlpm. and _xlop. before comparing, so a round-trip through it passes even when the stored form has lost one. It did: an inner LAMBDA parameter came out bare, which makes Excel reject the whole definition. unmarked_names() checks for that class separately.

Checks

Gate	Result
verify_workbook.py	OK, 134 functions, 211 parts
verify_sources.py	OK, 134 reproduced
verify_signatures.py	OK, 121 signatures, 126 tables, 123 example blocks
verify_index.py	OK, 134 rows
verify_previous_names.py	OK, 4 recording no previous name
verify_afe.py	OK
python -m unittest discover -s tools/tests	OK, 63 tests
excel_selftest.ps1	438 assertions, 0 failed (was 259)
verify_cache.py	OK, 20,228 values unchanged

The liability is checked against Excel's own NPV, an independent oracle rather than a restatement of the same arithmetic. The schedule is checked by identity across four rates, four term lengths and both timings: it closes to nil, each opening is the closing before it, and every period reconciles. Both identities name a row, because a whole-block total cancels the row under test.

The pass is idempotent: a second run reports "already applied" and writes nothing. Registered in test_idempotency.py.

Scope

Paragraph references were read against the AASB 16 compilation on 24 August 2026: paragraphs 23, 24, 26, 27, 39, 42(b) and 43. Nothing was carried across from a search result summary.

These are schedules, not determinations. They do not decide the lease term, decide what counts as a lease payment, decide whether an arrangement contains a lease, or apply the short-term and low-value recognition exemptions. No lessor accounting.