feat: add Wales infrastructure and Green Manifesto scoring#29
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nikhilwoodruff wants to merge 3 commits intomainfrom
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feat: add Wales infrastructure and Green Manifesto scoring#29nikhilwoodruff wants to merge 3 commits intomainfrom
nikhilwoodruff wants to merge 3 commits intomainfrom
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Adds the foundational Wales-specific model components needed to score Welsh manifesto policies, plus the first scoreable reforms. Infrastructure: - `is_in_wales` flag on Person, derived from household region (parallel to `is_in_scotland`) - `Region::is_wales()` method - Welsh Land Transaction Tax (LTT) as a separate parameter block, applied to Welsh households instead of SDLT via `calculate_property_transaction_tax()` - Nation-specific council tax Band D rates (`wales_average_band_d`, `scotland_average_band_d`) so CT reforms can be scoped to a single nation - `FreeSchoolMealsParams` with `wales_primary_universal` / `wales_secondary_universal` flags; calculated FSM flows through to net income when params are present - OBR fiscal headroom context parameters (`obr_fiscal_headroom_bn: 9.9`, `obr_headroom_sensitivity: 1.0`) — UK-wide metadata, not used in simulation computation Parameters (2025/26): - LTT residential bands (Welsh Government rates: 0%/6%/7.5%/10%/12%) - Wales Band D CT: £1,955; Scotland: £1,528 - Baseline FSM: `wales_primary_universal: true` (current policy since Jan 2024) - OBR Spring Statement 2026 headroom: £9.9bn Council tax now enters `total_tax` and uses `council_tax_calculated` for both fiscal accounting and AHC housing costs, with reform changes flowing through to BHC net income via a CT adjustment. Reform: `reforms/wales_green_manifesto.yaml` — scores: 1. Abolish Wales council tax (`wales_average_band_d: 0.0`): -£3.7bn, 7.4% gain, avg +£1,779/yr 2. Extend universal FSM to secondary pupils in Wales (`wales_secondary_universal: true`) Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
…ment Adds proper Local Housing Allowance cap logic for private renters on HB and UC housing element. The model previously used full reported rent as eligible rent for all tenures, overstating HB/UC for private renters above their LHA cap. Changes: - LhaParams struct with region×bedroom-category monthly rate table (12 regions × 5 categories A–E), private_rent_index multiplier for reform scenarios, and enabled flag - lha_bedroom_entitlement() implements UC Regs 2013 Sch.4 / HB Regs 2006 Sch.B1: same-sex children over 10 share first, remainder share in pairs - lha_monthly_cap() applies cap only to TenureType::RentPrivately - Both calculate_housing_benefit() and calculate_universal_credit() now apply the LHA cap to eligible rent for private renters - 2025/26 rates from VOA list of rents (2020 data, uprated to April 2024 using ONS IPHRP index, frozen at that level for 2025/26 re-freeze) - 6 new unit tests covering bedroom entitlement and cap behaviour EFRS calibration needs to be rerun to recalibrate weights against the updated simulated HB/UC values: python scripts/rebuild_all.py --only efrs Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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Adds Wales-specific modelling infrastructure, scores two Wales Green Manifesto 2026 policies, and properly implements the LHA cap for private renters.
Wales infrastructure
is_in_walesflag onPerson, auto-derived from household regionwales_average_band_d,scotland_average_band_d) so CT reforms can be scoped to one nationFreeSchoolMealsParamswithwales_primary_universal/wales_secondary_universalflagsobr_fiscal_headroom_bn: 9.9bn) — Spring Statement 2026, used in reform impact summariesCouncil tax now enters
total_taxand uses a scaling approach (reform_band_d / baseline_band_d × reported FRS amount) rather than recalculating from inaccurate 1991 property band thresholds.Wales Green Manifesto reform (
reforms/wales_green_manifesto.yaml): council tax abolition in Wales (~£3.7bn/yr) and extending universal FSM to secondary pupils.LHA cap
Private renters on HB and UC now have eligible rent capped at the LHA rate for their region and bedroom entitlement. Previously, full reported rent was used for all tenures, overstating housing support for private renters above their cap.
lha_bedroom_entitlement()implements UC Regs 2013 Sch.4 / HB Regs 2006 Sch.B1 sharing rulesprivate_rent_indexscalar for reform scenarios (e.g. 1.10 = 10% LHA uplift)TenureType::RentPrivately; social renters unaffectedNote: EFRS calibration weights need regenerating after this change — run
python scripts/rebuild_all.py --only efrs.