Slice S0380.89: Table 4d responsiveness dispatch + screed-UFH bug fix + strict raise

SAP 10.2 Table 4d (PDF p.170) "Heating type and responsiveness ...
depending on heat emitter":

  Heat emitter                                        R
  -------------------------------------------------   -----
  Systems with radiators                              1.0
  Underfloor (wet) — pipes in insulated timber floor  1.0
  Underfloor (wet) — pipes in screed above insulation 0.75
  Underfloor (wet) — pipes in concrete slab           0.25
  Warm air via fan coil units                         1.0

Pre-S0380.89 the cascade `_responsiveness` had:

    if isinstance(emitter, int) and emitter == 2:
        return 0.25
    return 1.0

But the Elmhurst cert-side enum (`_ELMHURST_HEAT_EMITTER_TO_SAP10` at
`datatypes/epc/domain/mapper.py:3646`) maps:

    1 = Radiators
    2 = Underfloor (in screed)         ← spec R=0.75, NOT 0.25
    3 = Underfloor (timber floor)
    4 = Warm air
    5 = Fan coils

The cascade silently treated screed UFH (Elmhurst code 2) as
concrete-slab UFH (R=0.25 — Table 4d's most thermally massive UFH
variant). The bug halved the actual spec responsiveness — for a screed
UFH cert, off-period temperature reduction was computed with R=0.25
instead of R=0.75, materially under-counting MIT drop and over-counting
SH demand.

The bug is latent on cohort + golden because `_first_main_heating`
picks main[0] and almost all certs lodge radiators (emitter=1) there.
Corpus audit (full JSON sweep): emitter=2 appears on 2 records and
in both cases on a secondary main slot (e.g. golden cert
0240-0200-5706-2365-8010 main[1]) — never on the selected first main.
The fix preempts the next cert that lodges screed UFH on main[0].

Fix:

  - New `_RESPONSIVENESS_BY_EMITTER_CODE` dispatch dict reflecting
    Table 4d per the Elmhurst cert-side enum (1: 1.0, 2: 0.75, 3: 1.0,
    4: 1.0, 5: 1.0). "Concrete slab UFH" (Table 4d R=0.25) has no
    cert-side enum entry — that variant would need a new mapper code
    before the cascade can dispatch it.
  - `_responsiveness` flipped to strict-raise per [[reference-
    unmapped-sap-code]]: absent lodging (None / 0 / "") returns modal
    R=1.0 default; lodging present but unmapped raises
    `UnmappedSapCode("heat_emitter_type", value)`.

Tests (4 new, AAA-structure):

  - `test_heat_emitter_code_2_underfloor_in_screed_routes_to_responsiveness_0p75_per_table_4d`
    pins the bug fix: emitter=2 → R=0.75 (was 0.25)
  - `test_heat_emitter_code_dispatch_table_4d_full_coverage`
    pins all 5 Elmhurst emitter codes to spec-correct R
  - `test_responsiveness_raises_unmapped_sap_code_on_unknown_emitter`
    pins the strict-raise contract (hypothetical code 99 raises)
  - `test_responsiveness_default_1p0_when_emitter_lodging_absent`
    pins the absent-lodging contract (None / 0 / "" → 1.0)

Test baseline: 568 pass (was 564 + 4 new) + 9 expected
`test_sap_result_pin[000565-*]` fails unchanged. Cohort + golden
unaffected (all use emitter=1 on main[0]).

Pyright net-zero per touched file (one `pyright: ignore` added on the
absent-lodging test where `main_heating_control=None` is passed to a
dataclass declaring `Union[int, str]` — runtime data exhibits None
on certs lacking space-heating controls, so the test covers a real
codepath the type system doesn't model).

Per the user-requested "we keep debugging silent fallbacks" mandate,
this is the second slice (after S0380.88) in the strict-raise series.
Next candidates per [[reference-unmapped-sap-code]]: PV pitch +
overshading, meter→tariff, heat-network DLF, secondary-heating
fraction by category.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

domain/sap10_calculator/rdsap/cert_to_inputs.py

@@ -842,14 +842,49 @@ def _control_type(main: Optional[MainHeatingDetail]) -> int:
 
 
 def _responsiveness(main: Optional[MainHeatingDetail]) -> float:
-    """SAP 10.2 Table 9b responsiveness R ∈ [0, 1]. Radiators ≈ 1.0;
+    """SAP 10.2 Table 4d (PDF p.170) heat-emitter responsiveness R ∈ [0, 1].
-    underfloor ≈ 0.25. Defaults to radiators."""
+
+    Cert-side heat_emitter_type enum (per `_ELMHURST_HEAT_EMITTER_TO_SAP10`
+    at datatypes/epc/domain/mapper.py:3646):
+        1 = Radiators                                  → R = 1.0
+        2 = Underfloor (in screed above insulation)    → R = 0.75
+        3 = Underfloor (timber floor)                  → R = 1.0
+        4 = Warm air                                   → R = 1.0
+        5 = Fan coils                                  → R = 1.0
+
+    "Concrete slab" UFH (Table 4d R=0.25) has no cert-side enum entry
+    yet — that variant would need a new mapper code before the cascade
+    can dispatch it.
+
+    Strict-dispatch per [[reference-unmapped-sap-code]]: absent lodging
+    (None / 0 / "") returns modal default R=1.0 (radiators); lodging
+    present but unmapped raises `UnmappedSapCode` so the spec-coverage
+    gap surfaces at test time.
+    """
     if main is None:
         return 1.0
     emitter = main.heat_emitter_type
-    if isinstance(emitter, int) and emitter == 2:
+    if not emitter:
-        return 0.25
+        return 1.0
-    return 1.0
+    if isinstance(emitter, int) and emitter in _RESPONSIVENESS_BY_EMITTER_CODE:
+        return _RESPONSIVENESS_BY_EMITTER_CODE[emitter]
+    raise UnmappedSapCode("heat_emitter_type", emitter)
+
+
+# SAP 10.2 Table 4d (PDF p.170) — heat-emitter responsiveness R.
+# Keyed on the Elmhurst-mapper cert-side integer enum (mirrored by the
+# API mapper which passes the integer through directly). Pre-S0380.89
+# the cascade had `if emitter == 2: return 0.25` — silently mis-treating
+# screed UFH (spec R=0.75) as concrete-slab UFH (spec R=0.25). The
+# spec R-table is keyed on physical emitter category, not on a single
+# "underfloor" lumping.
+_RESPONSIVENESS_BY_EMITTER_CODE: Final[dict[int, float]] = {
+    1: 1.0,   # Radiators
+    2: 0.75,  # Underfloor (in screed above insulation)
+    3: 1.0,   # Underfloor (timber floor)
+    4: 1.0,   # Warm air
+    5: 1.0,   # Fan coils
+}
 
 
 def _main_fuel_code(main: Optional[MainHeatingDetail]) -> Optional[int]:

domain/sap10_calculator/rdsap/tests/test_cert_to_inputs.py

@@ -35,6 +35,7 @@ from domain.sap10_calculator.calculator import Sap10Calculator, SapResult
 from domain.sap10_calculator.rdsap.cert_to_inputs import (
     _has_suspended_timber_floor_per_spec,  # pyright: ignore[reportPrivateUsage]
     _main_floor_u_value,  # pyright: ignore[reportPrivateUsage]
+    _responsiveness,  # pyright: ignore[reportPrivateUsage]
     _water_heating_worksheet_and_gains,  # pyright: ignore[reportPrivateUsage]
     UnmappedSapCode,
     cert_to_demand_inputs,
@@ -903,6 +904,115 @@ def test_cert_to_inputs_raises_unmapped_sap_code_on_unknown_main_heating_control
     assert excinfo.value.value == 2998
 
 
+def test_heat_emitter_code_2_underfloor_in_screed_routes_to_responsiveness_0p75_per_table_4d() -> None:
+    # Arrange — SAP 10.2 Table 4d (PDF p.170, "Heating type and
+    # responsiveness ... depending on heat emitter"):
+    #
+    #   Underfloor heating (wet system):
+    #     pipes in insulated timber floor      R = 1.0
+    #     pipes in screed above insulation     R = 0.75   ← Elmhurst code 2
+    #     pipes in concrete slab               R = 0.25
+    #
+    # The Elmhurst mapper at `_ELMHURST_HEAT_EMITTER_TO_SAP10` defines
+    # the cert-side integer enum: 1=Radiators, 2=Underfloor (in screed),
+    # 3=Underfloor (timber floor), 4=Warm air, 5=Fan coils. Pre-S0380.89
+    # `_responsiveness` had `if emitter == 2: return 0.25` — silently
+    # treating screed UFH as concrete-slab UFH (R=0.25 instead of the
+    # spec-correct R=0.75). Underfloor in screed has 3× the
+    # responsiveness the cascade was assigning it.
+    #
+    # The bug is mostly latent because (a) `_first_main_heating` picks
+    # main[0] and most certs lodge radiators there, (b) emitter=2 only
+    # appears on main[1] in the corpus (e.g. golden cert
+    # 0240-0200-5706-2365-8010 — but that cert's main[0] is emitter=1
+    # so the bug doesn't surface). Fixing it preempts the next cert that
+    # legitimately lodges screed UFH on main[0].
+
+    main = MainHeatingDetail(
+        has_fghrs=False, main_fuel_type=26, heat_emitter_type=2,
+        emitter_temperature=1, main_heating_control=2106,
+        main_heating_category=2, sap_main_heating_code=102,
+    )
+
+    # Act
+    result = _responsiveness(main)
+
+    # Assert — SAP 10.2 Table 4d "pipes in screed above insulation" R=0.75
+    assert abs(result - 0.75) <= 1e-9
+
+
+def test_heat_emitter_code_dispatch_table_4d_full_coverage() -> None:
+    # Arrange — SAP 10.2 Table 4d responsiveness by Elmhurst-mapper
+    # heat_emitter_type code (per `_ELMHURST_HEAT_EMITTER_TO_SAP10` at
+    # datatypes/epc/domain/mapper.py:3646):
+    #
+    #   Code  Emitter type                  R
+    #   ----  ----------------------------  ----
+    #   1     Radiators                     1.0
+    #   2     Underfloor (in screed)        0.75
+    #   3     Underfloor (timber floor)     1.0
+    #   4     Warm air                      1.0
+    #   5     Fan coils                     1.0
+    #
+    # No Elmhurst code maps to "concrete slab UFH" (R=0.25 per Table 4d).
+    # That category would need a new cert-side enum entry first.
+
+    def _main_with(emitter_code: int) -> MainHeatingDetail:
+        return MainHeatingDetail(
+            has_fghrs=False, main_fuel_type=26, heat_emitter_type=emitter_code,
+            emitter_temperature=1, main_heating_control=2106,
+            main_heating_category=2, sap_main_heating_code=102,
+        )
+
+    # Act / Assert
+    assert abs(_responsiveness(_main_with(1)) - 1.0) <= 1e-9
+    assert abs(_responsiveness(_main_with(2)) - 0.75) <= 1e-9
+    assert abs(_responsiveness(_main_with(3)) - 1.0) <= 1e-9
+    assert abs(_responsiveness(_main_with(4)) - 1.0) <= 1e-9
+    assert abs(_responsiveness(_main_with(5)) - 1.0) <= 1e-9
+
+
+def test_responsiveness_raises_unmapped_sap_code_on_unknown_emitter() -> None:
+    # Arrange — same strict-raise contract as `_control_type` per
+    # [[reference-unmapped-sap-code]]: lodging present but unmapped
+    # raises so the spec-coverage gap surfaces at test time. A code
+    # outside the dispatch dict (e.g. hypothetical code 9 = "Solid
+    # fuel stove" or future enum value) must raise, not silently
+    # return the radiators default.
+    main = MainHeatingDetail(
+        has_fghrs=False, main_fuel_type=26, heat_emitter_type=99,  # not in dispatch
+        emitter_temperature=1, main_heating_control=2106,
+        main_heating_category=2, sap_main_heating_code=102,
+    )
+
+    # Act / Assert
+    with pytest.raises(UnmappedSapCode) as excinfo:
+        _responsiveness(main)
+    assert excinfo.value.field == "heat_emitter_type"
+    assert excinfo.value.value == 99
+
+
+def test_responsiveness_default_1p0_when_emitter_lodging_absent() -> None:
+    # Arrange — emitter lodging absent (None / 0 / "") returns modal
+    # default R=1.0 (radiators). Corpus has 4 certs lodging emitter=0
+    # as the "no main heating system present" sentinel. Mirror of the
+    # control-type absent-lodging contract from S0380.88.
+
+    def _main_with(emitter_value: object) -> MainHeatingDetail:
+        return MainHeatingDetail(
+            has_fghrs=False, main_fuel_type=26,
+            heat_emitter_type=emitter_value,  # type: ignore[arg-type]
+            emitter_temperature=1, main_heating_control=2106,
+            main_heating_category=2, sap_main_heating_code=102,
+        )
+
+    # Act / Assert
+    assert _responsiveness(None) == 1.0
+    assert _responsiveness(_main_with(0)) == 1.0
+    assert _responsiveness(_main_with("")) == 1.0
+    assert _responsiveness(_main_with(None)) == 1.0
+
+
 def test_cert_to_inputs_does_not_raise_when_main_heating_control_is_missing() -> None:
     # Arrange — distinguish "lodging absent" (cert didn't lodge a control
     # code at all → cascade default OK) from "lodging present but unmapped"
@@ -921,7 +1031,8 @@ def test_cert_to_inputs_does_not_raise_when_main_heating_control_is_missing() ->
             main_heating_details=[
                 MainHeatingDetail(
                     has_fghrs=False, main_fuel_type=26, heat_emitter_type=1,
-                    emitter_temperature=1, main_heating_control=None,
+                    emitter_temperature=1,
+                    main_heating_control=None,  # pyright: ignore[reportArgumentType]
                     main_heating_category=2, sap_main_heating_code=102,
                 ),
             ],