Read SNAP utility allowance incurrence from the canonical heating inputs

[hua7450]

Stage 2a of the heating-input consolidation (#9284, under the #9275 atomic-inputs rule), following the foundation PR #9360. This half moves SNAP's utility-allowance incurrence and the utility-count variables onto the canonical heating inputs and fixes two latent gaps in the individual and limited allowance paths. Stage 2b (Michigan home heating credit + the #8964 utilities-responsibility projection) is a separate PR because it carries a partner-facing default flip.

What the regulation says

7 CFR 273.9(d)(6)(iii):

• (D)(1) The heating and cooling standard (HCSUA) must be available to households that incur heating or cooling expenses separately from their rent or mortgage.
• (A)(1) An individual standard for each type of utility expense; FNS publishes one standard for gas and fuel together.
• (A)(3) The LUA covers electricity and fuel for purposes other than heating or cooling, water, sewerage, trash, optionally telephone, and must include at least two utilities.

Changes

Variable	Before	After
has_cooling_expense	—	New input (SPM unit, bool). Cooling is not derivable from an electricity bill, so it is its own fact.
has_gas_and_fuel_expense	—	New derived bool: any of gas_expense, bottled_gas_expense, fuel_oil_expense, wood_expense, coal_expense, other_heating_fuel_expense, cooking_fuel_expense > 0. One SNAP standard, one incurrence flag.
has_heating_cooling_expense	heating_cooling_expense > 0	(heating_expense > 0 & ~heat_expense_included_in_rent) | has_cooling_expense | (UNSPECIFIED & heating_cooling_expense > 0)
count_distinct_utility_expenses	heating_cooling, electricity, gas, phone, trash, water, sewage	same categories, with gas replaced by has_gas_and_fuel_expense so deliverable and cooking fuels count (once)
snap_individual_utility_allowance	gas-and-fuel standard incurred only by gas_expense	incurred by has_gas_and_fuel_expense
utility_expense	adds of heating_cooling + gas + electricity + water/sewage/trash/phone	formula: all per-fuel bills + water/sewage/trash/phone, plus heating_cooling_expense only for UNSPECIFIED households
IL AABD utility_types	metered_gas_expense	gas_expense (parameter node stays metered_gas, the regulation's term, via a key override in the formula)
metered_gas_expense	read by IL AABD	deprecated, no readers

Behavior preservation

The same UNSPECIFIED gate as #9360: a household that does not send heating_type keeps its pre-canonical signal (heating_cooling_expense > 0), which still ignores heat_expense_included_in_rent exactly as before. Live traffic check (household API analytics, 14 days to 2026-09-06): heating_cooling_expense + has_heating_cooling_expense ride on 65% of all requests as the SNAP signal, always without heating_type; metered_gas_expense, has_cooling_expense, and every deliverable-fuel column have zero traffic. So no partner value moves from the incurrence change.

Two value changes are possible only for households that send the affected columns:

• A household sending a deliverable or cooking fuel bill (no metered gas) with no heating/cooling signal now incurs the gas-and-fuel standard on the IUA path and counts one more utility toward the LUA. This is the (A)(1) fix; there is no live traffic on those columns.
• A household sending metered_gas_expense to IL AABD gets no metered gas allowance until it sends gas_expense (zero traffic; the one analytics-coverage fixture is migrated in this PR).

Canonical households (a known heating_type): heating incurrence follows the primary fuel's bill and is switched off by heat_expense_included_in_rent per (D)(1); a heat-in-rent home with gas and electricity bills lands on the LUA. A known type never reads heating_cooling_expense, so the migration contract from #9360 holds: send the canonical inputs, not both vocabularies.

Not in this PR

• HCSUA entitlement through a LIHEAP payment over $20 ((D)(3), "Heat and Eat") — tracked in Track OBBBA "Heat and Eat" HCSUA eligibility change for FY2026 #7745.
• Excluding the primary heating fuel's own bill from the LUA utility count. Under the SUA-first ordering it only matters for a heat-in-rent household whose known heating fuel also has a separate bill, where that bill is fuel for other purposes anyway.
• Stage 2b: MI home heating credit onto heating_expense and heat_expense_included_in_rent (MCL 206.527a(1)(c) halves the standard credit when "heating costs are included in the claimant's rent"), plus the Reconcile tenant_pays_utilities (Household) and utilities_included_in_rent (TaxUnit): near-inverse vars, different entities, contradictory defaults #8964 tenant_pays_utilities projection and default flip (partner notification gate).
• Stage 3: deleting the UNSPECIFIED-gated legacy branches and the deprecated inputs after partner migration. The UNSPECIFIED enum value itself stays (it still means "heating fuel not supplied"); only the fallback code behind it goes.

Tests

• New: has_heating_cooling_expense (11 cases: legacy signal, per-fuel bill alone, heat in rent on canonical vs legacy paths, cooling with and without heating, known type ignoring the legacy input), has_gas_and_fuel_expense (6), utility_expense (4, including the no-double-count case).
• Appended: count_distinct_utility_expenses (deliverable fuel counts, gas + propane counts once, cooking fuel), snap_individual_utility_allowance (fuel oil only, gas + propane once, wood + cooking fuel once), snap_utility_allowance_type (five end-to-end cases from canonical inputs through both derived variables), IL AABD (gas_expense pays the metered gas allowance; metered_gas_expense no longer read).

Refs: #9284, #9275, #9360, #7745.

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Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (f9b5549) to head (255a25a).
⚠️ Report is 52 commits behind head on main.

Additional details and impacted files

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  Files            2         8     +6     
  Lines           20       126   +106     
  Branches         0         3     +3     
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