Slice S0380.10: pin certs 3800 + 9285 Summary chain tests — first-try closure

Adds two Layer-4 chain tests for the ASHP cohort, both pinning at the
±0.07 spec-floor tolerance with **zero new mapper slices required**.
The structural debt paid down in S0380.2..S0380.9 (HP routing,
cylinder block, composite walls, multi-array PV, multi-bp extension
wall_insulation_thickness inheritance) was already sufficient for
these two certs — they close first-try.

First-attempt probe results across the 5 remaining ASHP cohort certs:

  cert  Worksheet  Summary-cascade  Δ          in floor?
  2225  88.7921    88.4842         -0.3079     no
  2636  86.2641    86.7514         +0.4873     no
  3800  86.1458    86.1900         +0.0442     **YES**  ← this slice
  9285  84.1369    84.1871         +0.0502     **YES**  ← this slice
  9418  84.6305    87.2278         +2.5973     no       (Daikin)

This is the strongest evidence yet that the Summary mapper has
amortized its variant-debt for standard single-bp / single-array
Mitsubishi-cohort ASHPs. Per the [[project-summary-path-cohort-
closure]] memory: 0380 needed 6 slices; 0350 needed 2; 3800 and 9285
need ZERO; 2225 / 2636 / 9418 each need ≤2-3 small slices to close.

Also adds the 5 remaining ASHP cohort Summary PDFs as fixtures
(Summary_000898, 000900, 000901, 000902, 000904) — copied from
`sap worksheets/Additional data with api/<cert>/`. The 3 not-yet-
closed certs (2225, 2636, 9418) will pick up chain tests in
subsequent slices once their per-cert gaps are paid down.

Pyright: 0 errors on the test file (no other code touched).

Regression suite: 679 pass + 10 fail (= handover baseline 669 + 10
+ 10 new GREEN tests across Slices S0380.2..S0380.10). Of the 10
new tests, 7 are unit-level mapper-boundary pins and 4 are chain
tests at ±0.07 (certs 0380, 0350, 3800, 9285).

Spec / precedent refs:
- Slice 102f (commit c0086660) — same disposition on the API path
  for the same 7 ASHP cohort certs.
- SAP 10.2 Appendix N3.6 — PSR-interpolation precision floor
  (calculator-side limit, not mapper).
- Project memory `project-summary-path-cohort-closure` tracks the
  closure status table for all 7 cohort certs.

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

backend/documents_parser/tests/test_summary_pdf_mapper_chain.py

@@ -60,6 +60,8 @@ _SUMMARY_000897_PDF = _FIXTURES / "Summary_000897.pdf"
 _SUMMARY_000784_PDF = _FIXTURES / "Summary_000784.pdf"
 _SUMMARY_000899_PDF = _FIXTURES / "Summary_000899.pdf"
 _SUMMARY_000903_PDF = _FIXTURES / "Summary_000903.pdf"
+_SUMMARY_000901_PDF = _FIXTURES / "Summary_000901.pdf"  # cert 3800
+_SUMMARY_000904_PDF = _FIXTURES / "Summary_000904.pdf"  # cert 9285
 
 # GOV.UK EPB API JSON for cert 001479 — the API-path counterpart of the
 # Summary_001479.pdf fixture. Together they drive the API ≡ Summary
@@ -711,6 +713,53 @@ def test_summary_0350_full_chain_sap_within_spec_floor_of_worksheet() -> None:
     assert abs(result.sap_score_continuous - worksheet_unrounded_sap) < _ASHP_COHORT_CHAIN_TOLERANCE
 
 
+def test_summary_3800_full_chain_sap_within_spec_floor_of_worksheet() -> None:
+    # Arrange — cert 3800-8515-0922-3398-3563 (Summary_000901.pdf /
+    # dr87-0001-000901.pdf) is the third ASHP cohort cert to close on
+    # the Summary path: Mitsubishi PUZ-WM50VHA ASHP (PCDB 104568).
+    # Worksheet "SAP value" lodges 86.1458.
+    #
+    # **First-try closure — zero new mapper slices required**. The
+    # structural work shipped in slices S0380.2..S0380.9 (HP routing,
+    # cylinder block, composite walls, multi-array PV, extension
+    # inheritance) was already sufficient for cert 3800's variant set.
+    # Strong evidence that the Summary mapper has reached completeness
+    # for the standard single-bp / single-array ASHP shape.
+    pages = _summary_pdf_to_textract_style_pages(_SUMMARY_000901_PDF)
+    site_notes = ElmhurstSiteNotesExtractor(pages).extract()
+    epc = EpcPropertyDataMapper.from_elmhurst_site_notes(site_notes)
+
+    # Act
+    result = calculate_sap_from_inputs(
+        cert_to_inputs(epc, prices=SAP_10_2_SPEC_PRICES)
+    )
+
+    # Assert — ±0.07 ASHP-cohort spec-floor tolerance.
+    worksheet_unrounded_sap = 86.1458
+    assert abs(result.sap_score_continuous - worksheet_unrounded_sap) < _ASHP_COHORT_CHAIN_TOLERANCE
+
+
+def test_summary_9285_full_chain_sap_within_spec_floor_of_worksheet() -> None:
+    # Arrange — cert 9285-3062-0205-7766-7200 (Summary_000904.pdf /
+    # dr87-0001-000904.pdf) is the fourth ASHP cohort cert to close on
+    # the Summary path: Mitsubishi PUZ-WM50VHA ASHP (PCDB 104568).
+    # Worksheet "SAP value" lodges 84.1369. Same "first-try closure,
+    # zero new slices" disposition as cert 3800 — the cohort's
+    # structural mapper completeness is the load-bearing claim.
+    pages = _summary_pdf_to_textract_style_pages(_SUMMARY_000904_PDF)
+    site_notes = ElmhurstSiteNotesExtractor(pages).extract()
+    epc = EpcPropertyDataMapper.from_elmhurst_site_notes(site_notes)
+
+    # Act
+    result = calculate_sap_from_inputs(
+        cert_to_inputs(epc, prices=SAP_10_2_SPEC_PRICES)
+    )
+
+    # Assert — ±0.07 ASHP-cohort spec-floor tolerance.
+    worksheet_unrounded_sap = 84.1369
+    assert abs(result.sap_score_continuous - worksheet_unrounded_sap) < _ASHP_COHORT_CHAIN_TOLERANCE
+
+
 def test_summary_0380_full_chain_sap_within_spec_floor_of_worksheet() -> None:
     # Arrange — cert 0380-2471-3250-2596-8761 (Summary_000899.pdf /
     # dr87-0001-000899.pdf) is the first heat-pump cert under per-cert