docs: refresh NEXT_AGENT_PROMPT for PV β-split slices 4-6

Replaces stale legacy content (cert-mapper-validation workflow, dated
to a 9-triple staging slice) with the current handoff: branch state,
3 shipped slices (S0380.44 → S0380.46), and concrete directives for
the 3 remaining slices (cost cascade wiring, E_PV magnitude audit,
final fixture re-pin).

Companion to docs/HANDOVER_PV_BETA_SPLIT.md.

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

domain/sap10_calculator/docs/NEXT_AGENT_PROMPT.md

@@ -1,365 +1,57 @@
-# Handover — Per-cert validation workflow, 9 new triples staged
+# Next-agent prompt — PV β-split slices 4-6
 
-You are picking up branch `feature/per-cert-mapper-validation`
-(off main at `7fba27a7`, where the prior `ara-backend-design-prd`
-work was merged via PR #1123). The user has shifted focus from
-"close cert 001479 to 1e-4" (done — Slice 95) to "validate the
-API mapper against more cert pairs to surface remaining mapping
-gaps". 9 new (Summary + worksheet + API) triples have been
-provided. The mapping is acknowledged-incomplete; expect many
-mapper-completion slices.
+Branch: `feature/per-cert-mapper-validation`. HEAD: `beb0db95` (docs commit on top of S0380.46 `5b269f23`).
 
-## The user's stated workflow (verbatim)
+Read `domain/sap10_calculator/docs/HANDOVER_PV_BETA_SPLIT.md` end-to-end before any tool call. It has the full state, the 3 slices shipped (S0380.44 → S0380.46), the residual table showing where each cert sits, and the concrete plans for the 3 remaining slices.
 
-> we pick one [cert], we then pass the Elmhurst summary document to
-> `EpcPropertyDataMapper` to map the site notes data to
-> `EpcPropertyData`, we then pass to the SAP calculator. If the
-> output of the SAP calculator matches the SAP worksheet correctly,
-> we know we have correctly mapped the EpcPropertyData. We then get
-> the API response, map to `EpcPropertyData` using
-> `EpcPropertyDataMapper`, then check if we have the same
-> `EpcPropertyData` as the summary report (or same for the fields we
-> care about). We also check we get the same result.
->
-> The `EpcPropertyData` objects matching is our signal that we've
-> done things correctly. So this validates our mapping.
+## My directives
 
-Translation: Summary path proves itself against the worksheet →
-becomes the canonical reference for the API path. This is Layer 2 +
-Layer 3 + Layer 4 of the validation stack.
+The PV β-split work is a 6-slice plan; 3/6 are shipped. Continue:
 
-## State at session start (this handover's baseline)
+1. **Slice 4 (S0380.47) — cost cascade β wiring.** [fuel_cost.py:182](../worksheet/fuel_cost.py) currently does `pv_credit = -pv_generation × pv_export_credit_gbp_per_kwh` — treats ALL PV as exported at 13.19 p/kWh. Per Appendix M1 §6, onsite-consumed PV should bill at the IMPORT price (Table 12a standard tariff ~18 p, or weighted high/low if off-peak meter). The β infrastructure is already in place (`pv_dwelling_kwh_per_yr` + `pv_exported_kwh_per_yr` on CalculatorInputs from Slice 2). Add a new `pv_dwelling_import_price_gbp_per_kwh` field, wire it in `cert_to_inputs` using the same off-peak meter logic as `_space_heating_fuel_cost_gbp_per_kwh`, and split the credit in fuel_cost.py.
 
-Most recent commits (`sap10_calculator` + `sap10_ml` are now at the
-repo root; `packages/domain/src/domain/` was removed):
+   This is the riskiest slice because every PV cert's SAP rating shifts. The cohort-1 + cohort-2 chain-test 1e-4 pins will need re-pinning — expect small Δ (~0.02-0.05 SAP per cert) so the new pins will still be tight against worksheets. Re-pin AS PART OF SLICE 4 so the suite stays green between commits.
 
-```
-6dc11e4d fix: resolve 10 remaining test_summary_pdf_mapper_chain failures
-09fb6f1b fix: address 22 project-wide test failures from previous sweep
-a7b08a4e refactor: move docs/sap-spec/ contents into domain/sap10_calculator/
-960130b0 deleted redundant packages folder
-68401c51 refactor: lift-and-shift packages/domain/src/domain/ml → domain/sap10_ml
-29ac35cc refactor: lift-and-shift packages/domain/src/domain/sap → domain/sap10_calculator
-... (87b6045c "fixed merge conflicts from main", 168e7f18, 94975f3b deletions)
-a75052dc chore: commit cert 001479 fixture + RdSAP/PCDF spec PDFs
-f502db8c Slice 95: API mapper TFA from per-bp dims + window area 2dp rounding
-```
+2. **Slice 5 (S0380.48) — E_PV magnitude audit.** The 7-cert ASHP+5kWh-battery cohort (0350/0380/2225/2636/3800/9285/9418) overshoots PE by +2.7..+8.1 because the cascade computes E_PV ≈ 3× the worksheet's value. For cert 0380: cascade thinks 2570 kWh/yr, worksheet uses 831 kWh/yr. Either `peak_power=3` in the API JSON is in non-kWp units, the cascade's S lookup is wrong, or ZPV is mis-mapped.
 
-Folder structure post-migration:
+   Concrete probes (in handover §"Slice 5 plan"):
+   - Compare cert 0380's API `peak_power=3` against the Elmhurst Summary PDF Section 19 for the same cert
+   - Compute cascade S for orientation=South, pitch=45°, overshading=1=None — compare to SAP Appendix U3.3 spec value (expected ~1100 kWh/m²/yr UK avg)
+   - Verify Table M1 ZPV[1] = 1.0 against spec
+   - Empirical test: set cert 0380 `peak_power = 1.0` and check if residuals close
 
-```
-domain/                         (PEP 420 namespace; no __init__.py)
-├── addresses/, postcode.py, tasks/
-├── sap10_calculator/           ← was packages/domain/src/domain/sap/
-│   ├── calculator.py, climate/, rdsap/, tables/, validation/, worksheet/
-│   ├── docs/                   ← was docs/sap-spec/
-│   │   ├── HANDOVER_NEXT.md, SAP_CALCULATOR.md
-│   │   ├── NEXT_AGENT_PROMPT.md  ← this file
-│   │   └── specs/              ← RdSAP 10, SAP 10.2 + 10.3, PCDF spec PDFs
-│   └── tables/pcdb/data/       ← pcdb10.dat + 7× pcdb_table_*.jsonl
-└── sap10_ml/                   ← was packages/domain/src/domain/ml/
-```
+   If it's a kWp interpretation bug, surface via the schema or API mapper.
 
-`Path(__file__).parents[N]` indices were rebased through the move
-(delta of 3); see `Dockerfile.test` (poppler-utils now installed for
-test_summary_pdf_mapper_chain.py).
+3. **Slice 6 (S0380.49) — final fixture re-pin + tolerance tightening.** Once Slices 4 + 5 ship, the ASHP cohort residuals should land near zero. Re-pin all affected golden fixtures; if the cluster lands tightly (~0.01 PE / ~0.001 CO2), tighten `_PE_ABS_TOLERANCE_KWH_PER_M2` / `_CO2_ABS_TOLERANCE_TONNES` accordingly per [[feedback-golden-residuals-near-zero]].
 
-## Test baselines you should see at HEAD `6dc11e4d`
+## Conventions preserved (carry forward)
 
-```bash
-PYTHONPATH=/workspaces/model python -m pytest \
-    backend/documents_parser/tests/test_summary_pdf_mapper_chain.py \
-    domain/sap10_calculator/worksheet/tests/test_e2e_elmhurst_sap_score.py \
-    domain/sap10_calculator/rdsap/tests/test_golden_fixtures.py \
-    --no-cov -q
-# Expect: 17/0 in mapper-chain + Layer 1 baseline + golden residual baseline
-```
+- 1e-4 across the board ([[feedback-one-e-minus-4-across-the-board]])
+- Worksheet, not API, is the chain-test target ([[feedback-worksheet-not-api-reference]])
+- Cross-mapper parity via cascade ([[feedback-cross-mapper-parity-via-cascade]])
+- Spec-floor skepticism ([[feedback-spec-floor-skepticism]])
+- Bigger slices OK for uniform work ([[feedback-bigger-slices-for-uniform-work]])
+- Golden residuals → ~0 ([[feedback-golden-residuals-near-zero]])
+- AAA test convention + `abs(diff) <= tol` ([[feedback-aaa-test-convention]], [[feedback-abs-diff-over-pytest-approx]])
+- Spec citation in commit messages ([[feedback-spec-citation-in-commits]])
+- One slice = one commit; stage by name; re-pin shifted fixtures IN SAME SLICE so suite stays green ([[feedback-commit-per-slice]])
+- Pyright net-zero per touched file
+- Strict-enum raises on unmapped labels
 
-Wider domain sweep (1654 / 20 baseline): 9 hand-built 001479
-skeleton + 10 cohort Layer 1 pins + 1 heat_transmission edge case
-= 20 RED, all pre-existing and orthogonal to mapper work.
+## First concrete actions
 
-**Layer 4 production gate**:
-`test_api_001479_full_chain_sap_matches_worksheet_pdf_exactly` —
-**GREEN at < 1e-4**. Keep it green.
+1. Re-run the diagnostic baseline at the bottom of `HANDOVER_PV_BETA_SPLIT.md` to confirm **763 pass + 0 fail** at HEAD.
 
-## The new test data
+2. Start Slice 4 by reading [fuel_cost.py:182](../worksheet/fuel_cost.py) and the existing `_space_heating_fuel_cost_gbp_per_kwh` in cert_to_inputs.py to understand the off-peak meter price-resolution logic. Mirror that pattern for the dwelling IMPORT price.
 
-Location: `sap worksheets/Additional data with api/<cert-ref>/`
+3. After Slice 4 lands and chain tests are re-pinned: Slice 5's first probe is comparing cert 0380's API `peak_power` against the Summary PDF lodgement. The golden-fixture cert 0380 is `0380-2471-3250-2596-8761`; its Summary PDF + dr87 worksheet live in `backend/documents_parser/tests/fixtures/` — Section 19 of the Summary carries the PV array lodgement.
 
-Each folder is named by the GOV.UK EPB certificate number. Contains:
+4. Slice 6 wraps up — re-pin, verify, document.
 
-- `Summary_NNNNNN.pdf` — Elmhurst-format site notes
-- `dr87-0001-NNNNNN.pdf` — worksheet (`dr87-` prefix is a Domna-tool
-  variant; same shape as the `P960-` worksheet for cert 001479)
+## Architecture lessons that landed this session (load-bearing)
 
-The API JSON is **not** in the folder — fetch from GOV.UK EPB using
-the cert-ref:
+- **β-split shape is uniform across PE / CO2 / Cost.** Each cascade had the same bug — credit ALL PV at one rate (IMPORT for PE; missing for CO2; EXPORT for cost). The spec-correct fix is uniformly onsite-at-IMPORT + exported-at-EXPORT. `CalculatorInputs.pv_dwelling_kwh_per_yr` + `pv_exported_kwh_per_yr` are shared cross-cascade state; each cascade adds its own factor-pair fields. `None` falls back to legacy single-rate for synthetic test constructions.
+- **The EXPORT factor is Table 12 code 60** ("electricity sold to grid, PV") at all three cascades — already in `domain/sap10_calculator/tables/table_12.py` for PE (0.501) and CO2 (monthly Table 12d). For Slice 4 cost, you'll reference the same code 60 export-price from Table 12a (typically 13.19 p/kWh for the spec price set).
+- **Cert 9501 is the validation pin.** It has PV but no battery, and its PE + CO2 residuals both closed to ~0 after Slices 2-3. Any future cascade refactor must keep cert 9501 closed.
 
-```python
-from backend.epc_client.epc_client_service import EpcClientService
-from dotenv import load_dotenv
-import os
-load_dotenv('/workspaces/model/backend/.env')  # OPEN_EPC_API_TOKEN
-svc = EpcClientService(auth_token=os.environ['OPEN_EPC_API_TOKEN'])
-raw = svc._fetch_certificate('<cert-ref>')   # raw JSON dict
-```
-
-Note: use `OPEN_EPC_API_TOKEN` not `EPC_AUTH_TOKEN` (the latter is
-for a different/legacy API).
-
-### 9 cert references + heating type + worksheet SAP
-
-| Cert ref | Worksheet | Heating | PCDB idx | Worksheet SAP | TFA | bps | Dwelling |
-|---|---|---|---|---|---|---|---|
-| `0330-2249-8150-2326-4121` | 000897 | **Mains gas boiler** | 10241 | 61.5993 | 69.14 | 2 | Mid-terrace house |
-| `0350-2968-2650-2796-5255` | 000903 | ASHP | 104568 | 84.1367 | 90.54 | 2 | Mid-terrace house |
-| `0380-2471-3250-2596-8761` | 000899 | ASHP | 104568 | 88.5104 | 60.43 | 1 | Semi-detached bungalow |
-| `2225-3062-8205-2856-7204` | 000900 | ASHP | 104568 | 88.7921 | 82.49 | 1 | End-terrace house |
-| `2636-0525-2600-0401-2296` | 000901 | ASHP | 104568 | 86.2641 | 82.10 | 1 | Mid-terrace house |
-| `3800-8515-0922-3398-3563` | 000898 | ASHP | 104568 | 86.1458 | 81.34 | 2 | Mid-terrace house |
-| `9285-3062-0205-7766-7200` | 000902 | ASHP | 104568 | 84.1369 | 85.90 | 1 | End-terrace house |
-| `9418-3062-8205-3566-7200` | 000896 | ASHP | 102421 | 84.6305 | 74.37 | 3 | End-terrace house |
-| `9501-3059-8202-7356-0204` | (RR cert — newest, added late in session) | **Mains gas boiler** | 19007 | (not measured) | — | — | Top-floor flat |
-
-**Heating-type split**:
-- 2 mains gas boilers: 0330, 9501 (validated mapper territory)
-- 7 ASHPs: 0350, 0380, 2225, 2636, 3800, 9285, 9418 (**brand-new
-  mapper territory — never validated**)
-
-One earlier mismatch — cert 0330's folder originally held the wrong
-property's Summary/worksheet (17 vs 21 Summerfield Road); the user
-fixed mid-session and Summary_000897/dr87-0001-000897 now match
-cert ref 0330 correctly. The other 8 were audited and match.
-
-## Major scope discovery — Heat Pumps
-
-7 of the 9 new certs are Air Source Heat Pumps (predominantly PCDB
-index 104568, one model 102421). The mapper has never been
-validated against a heat-pump cert — cohort certs + cert 001479 are
-all mains-gas boilers.
-
-**Cert 0380 (initial pilot attempt) showed catastrophic failures**:
-
-| Path | Cascade SAP | Δ vs worksheet 88.5104 |
-|---|---|---|
-| Summary mapper | 18.08 | **-70.43** |
-| API mapper | 70.14 | **-18.37** |
-
-Diff: Summary identified the heat pump as an 80%-efficient boiler
-(catastrophic); API correctly identified it as a heat pump with
-COP=2.3 but cascade output still −18 SAP below worksheet (fabric
-HLC 104 vs probably ~50 needed). The Summary mapper is
-fundamentally broken on heat pumps; the API mapper is
-partially-broken.
-
-**Recommendation**: defer the heat-pump certs until the boiler
-workflow is proven. Closing 7 ASHP certs is plausibly a 15-30 slice
-workstream (new mapper plumbing for PCDB COP, electric tariff
-costing for HW + space heating, Appendix N heat-pump efficiency
-adjustments, etc.). Cert 0380 (smallest TFA bungalow, single bp)
-is the pilot HP cert once boiler workflow is proven.
-
-## Pilot status — cert 0330 (mains-gas mid-terrace boiler)
-
-Same shape as cert 001479 (proven). API JSON staged at
-`domain/sap10_calculator/rdsap/tests/fixtures/golden/
-0330-2249-8150-2326-4121.json` (**uncommitted**). Summary PDF
-copied to
-`backend/documents_parser/tests/fixtures/Summary_000897.pdf`
-(**uncommitted**).
-
-### Cascade SAP comparison
-
-| Path | Cascade SAP | Δ vs worksheet 61.5993 |
-|---|---|---|
-| Summary mapper | 62.0660 | **+0.4667** (just over 0.5) |
-| API mapper | 63.7446 | **+2.1453** (≥2 SAP off) |
-| Δ API↔Summary | +1.6786 | (mapper paths disagree) |
-
-### Cascade-component diff (API vs Summary)
-
-```
-TFA:           90.56 = 90.56          ✓
-storeys:       2 = 2                  ✓
-HLC walls:     113.535 ≈ 113.520     (Δ +0.015 — negligible)
-HLC roof:      7.323 = 7.323          ✓
-HLC floor:     30.705 = 30.705        ✓
-HLC windows:   36.455 vs 29.741       (Δ +6.71 ← BIG)
-HLC doors:     11.100 = 11.100        ✓
-HLC party:     11.357 = 11.357        ✓
-HLC bridge:    28.347 = 28.347        ✓
-HLC total:     238.822 vs 232.093     (Δ +6.73 — all from windows)
-Inf ACH:       0.7382 = 0.7382        ✓
-HW kWh:        3172.65 vs 2112.00    (Δ +1060 ← BIG)
-Lighting kWh:  207.92 = 207.92        ✓
-Main eff:      0.8850 = 0.8850        ✓
-```
-
-Two specific gaps to investigate as separate slices:
-
-1. **Windows HLC +6.71 W/K** — likely `glazing_type=14` (cert 0330)
-   not in Slice 93's `_API_GLAZING_TYPE_TO_TRANSMISSION` (only codes
-   3 and 13 are mapped). Same shape as cert 001479's
-   `glazing_type=2` issue; extending the dict should close this.
-   Affects multiple certs that use code 14.
-
-2. **HW kWh +1060 (API 3172 vs Summary 2112)** — substantial
-   divergence in §4 hot water cascade. Needs probe of which
-   subsystem (occupancy N, shower outlets, electric_shower_count,
-   cylinder, etc.) the API mapper is reading wrong. Cert 0330
-   doesn't have the +0.5m upper-storey adjustment quirk cert 001479
-   needed (Slice 92), so different root cause likely.
-
-(The user observed: "the mapping is very much incomplete (hence we
-have some non 0 matches to elmhurst summary matches)" — non-1e-4
-matches are expected and tractable.)
-
-### 116 field-level divergences (API vs Summary)
-
-Most are cascade-equivalent surfacing differences (Slice 91-era
-descriptive strings + int/None vs explicit-bool patterns) — the
-same shape `_is_excluded_path` already handles for the cohort
-certs. New specific concrete diffs that DO affect the cascade:
-
-- `sap_windows[*].window_transmission_details` — Summary has
-  explicit U/g/data_source; API has None for `glazing_type=14`
-  (cascade falls back to default U → too high)
-- `sap_windows[*].frame_factor` — Summary 0.7, API None
-- `sap_windows[*].window_width / window_height` — same w*h area
-  rounding pattern as cert 001479 (handled in Slice 95)
-
-## Workflow recommendation for next slice queue
-
-For each new cert (after cert 0330 pilot lands):
-
-1. **Stage**: fetch API JSON, copy Summary PDF into fixtures
-2. **Probe**: run the cascade-component diff (recreate the inline
-   pattern; the probe takes both `summary_epc` and `api_epc`, lowers
-   via `cert_to_inputs`, diffs each subsystem)
-3. **Localise** the biggest cascade-component delta
-4. **Fix** the mapper to close it; one fix = one slice
-5. **Add Layer 4 1e-4 test** when both Summary and API paths hit
-   worksheet at 1e-4 (cert may pass Summary path first, then
-   iterate API mapper to catch up)
-6. **Commit**: stage by name (`git add <path>`), cite spec page
-   when implementing a spec rule
-
-### Cohort-style fixture pattern
-
-If a cert benefits from a hand-built fixture (Layer 1), mirror the
-cohort pattern at
-`domain/sap10_calculator/worksheet/tests/_elmhurst_worksheet_NNNNNN.py`
-— with prefix `_dr87_worksheet_NNNNNN.py` for the new Domna-tool
-worksheet variant.
-
-**WARNING (lesson from previous session)**: the cohort hand-builts
-encode non-spec quirks (e.g. `has_suspended_timber_floor=False` to
-mirror the worksheet's non-spec §(12) behaviour for 4 certs). Don't
-blindly trust the hand-builts as spec-correct; cross-check against
-the mapper's spec-inference output before committing.
-
-## Conventions (preserved from previous handover)
-
-- **One slice = one commit** — stage by name.
-- **AAA test convention** — literal `# Arrange / # Act / # Assert`
-  headers in every new test.
-- **`abs(diff) <= tol`** not `pytest.approx` (strict-pyright clean).
-- **1e-4 worksheet tolerance** when worksheet is available; ±0.5
-  fallback only for API-only goldens.
-- **Spec citation** in commit messages when a slice implements a
-  spec rule (quote RdSAP 10 / SAP 10.2/10.3 page reference).
-- **Pyright net-zero per file**. Baselines (re-verify at session
-  start):
-  - `datatypes/epc/domain/mapper.py`: 33
-  - `domain/sap10_calculator/worksheet/heat_transmission.py`: 13
-  - `domain/sap10_calculator/rdsap/cert_to_inputs.py`: 35
-  - `datatypes/epc/domain/epc_property_data.py`: 0
-
-## First actions for the next agent
-
-1. Confirm HEAD: `git log --oneline -1` → `6dc11e4d`.
-2. Re-baseline:
-   ```bash
-   PYTHONPATH=/workspaces/model python -m pytest \
-       backend/documents_parser/tests/test_summary_pdf_mapper_chain.py \
-       domain/sap10_calculator/worksheet/tests/test_e2e_elmhurst_sap_score.py \
-       domain/sap10_calculator/rdsap/tests/test_golden_fixtures.py \
-       --no-cov -q
-   ```
-3. Pick up cert 0330 pilot. Either continue from where I left off
-   (fixtures staged uncommitted, 2 specific gaps identified above)
-   OR pivot to a different boiler cert if 0330 turns out
-   problematic (cert 9501 is the other boiler — top-floor flat with
-   PCDB idx 19007).
-4. Commit cert 0330's fixtures (API JSON + Summary PDF) as the
-   foundation slice before working any mapper fixes:
-   ```bash
-   git add domain/sap10_calculator/rdsap/tests/fixtures/golden/0330-2249-8150-2326-4121.json
-   git add backend/documents_parser/tests/fixtures/Summary_000897.pdf
-   git commit -m "chore: stage cert 0330 fixtures (boiler pilot, worksheet SAP 61.5993)"
-   ```
-5. Add a RED Layer 2 test (Summary mapper cascade SAP at 1e-4
-   vs 61.5993) — establishes the failing target. Then fix the
-   Summary path mapper bugs slice-by-slice.
-6. Once Summary path is GREEN, do the same for the API path (Layer
-   4). The API mapper may need additional fixes Summary doesn't
-   need — they're independent paths into the same `EpcPropertyData`
-   shape.
-7. After cert 0330 lands as a clean Layer 4 1e-4 pin, repeat for
-   cert 9501 (the other boiler). 2 boiler certs proven is much
-   stronger evidence than 1.
-8. Then plan the heat-pump workstream. The 7 ASHP certs share a
-   PCDB index (104568) so much of the fix is likely shared. Write
-   a follow-up handover for that workstream specifically.
-
-## Heat-pump workstream sketch (deferred)
-
-When the user gives the go-ahead, work order:
-
-1. **API mapper**: surface `main_heating_index_number`, set
-   `main_heating_category` for HPs, `main_fuel_type=29` (electric
-   heat pump).
-2. **Cascade**: ensure `cert_to_inputs._main_heating_efficiency`
-   reads PCDB HP COP correctly. Investigate Table 4a/4b vs PCDB
-   precedence for HPs.
-3. **Fuel cost**: HW + space heating on electricity tariffs
-   (Table 12) — check if the cascade has electric-tariff fuel-cost
-   plumbing wired up.
-4. **Appendix N**: HP-specific efficiency adjustments (climate +
-   flow temperature). Likely the biggest cascade-side gap.
-5. **Summary mapper**: separate slice — needs to identify HPs from
-   the Summary PDF's heating section.
-
-## Open items / known gaps not yet addressed
-
-- 8 API-only golden cert residuals still range from 0 to -15 SAP
-  delta (cert 0240 is the outlier — see prior handover §4 and
-  `test_golden_fixtures.py` notes). The user's stated end goal is
-  <0.5 SAP error on all goldens; cert 0240 needs RR-description
-  parsing (or Room-in-Roof mapping investigation) + glazing_type=2
-  surfacing.
-- Layer 3 field-parity test
-  (`test_from_api_response_matches_from_elmhurst_site_notes_001479`)
-  still not written. Lower priority since cascade-output Layer 4
-  already gates parity.
-- The 4 cohort chain tests for non-spec §(12) certs were deleted
-  this session; if the user later sources spec-compliant
-  worksheets for 000474/000480/000487/000490, those tests can be
-  restored (with the spec-correct hand-builts).
-
-## Tooling shortcuts
-
-- **EPC fetch**: `OPEN_EPC_API_TOKEN` (NOT `EPC_AUTH_TOKEN`) in
-  `backend/.env`. `EpcClientService._fetch_certificate(cert_ref)`
-  returns the raw JSON dict.
-- **Worksheet SAP extract**: `pdftotext -layout <worksheet.pdf> -`
-  then `grep -E "SAP value\s+[0-9]+\.[0-9]+"`. Works for all
-  `dr87-`, `P960-`, and `U985-` worksheet variants.
-- **Cascade-component probe template**: see the cert-0330 probe
-  inline above; same shape as the cert-001479 probe.
-
-Good luck. The methodology is proven on cert 001479 and partially
-on cert 0330 (boiler pilot 95% closed). Each new cert pair should
-land in 1-5 mapper slices. Stage by name; one slice = one commit;
-cite spec when implementing a spec rule.
+Good luck. The β-implementation is spec-correct (cert 9501 proves it). Slices 4-5 surface the remaining bugs as forcing functions; Slice 6 finalises the closure.