diff --git a/docs/baseline-downgrade-followups.md b/docs/baseline-downgrade-followups.md
index 2157eb7f..0b7464c1 100644
--- a/docs/baseline-downgrade-followups.md
+++ b/docs/baseline-downgrade-followups.md
@@ -12,12 +12,15 @@ Each is **separate from** the full-SAP fix (`fix/baseline-downgrades`).
   `mechanical_ventilation_kind`. ✅
 - `21_0_1` — rich inline `SapVentilation(...)` incl. the kind. ✅
 - **`17_1` / `18_0` / `20_0_0`** — built `SapVentilation(sheltered_sides=…)` and
-  **dropped** the kind. **Fixed in this PR** (mirror `_api_mechanical_ventilation_kind`).
-- **`19_0` / `21_0_0`** — set **no `sap_ventilation` at all** → the dataclass
-  default empty object. They drop the **entire** ventilation block (sheltered
-  sides + kind + everything), not just the kind. **Still open** — a bigger,
-  separate consistency fix (give them a proper `sap_ventilation` construction,
-  mirroring 21.0.1), not a one-liner.
+  **dropped** the kind. **Fixed in #1333** (mirror `_api_mechanical_ventilation_kind`).
+- **`19_0` / `21_0_0`** — set **no `sap_ventilation` at all** → the
+  `EpcPropertyData` default (`None`). They dropped the **entire** ventilation
+  block (sheltered sides + kind), not just the kind. **Fixed in
+  `feat/rdsap-19-21-ventilation`**: both now construct `SapVentilation(...)`
+  mirroring 21.0.1, but only for the fields each schema lodges — the top-level
+  `mechanical_ventilation` enum (→ kind) and `sheltered_sides` (from
+  `built_form`). Neither lodges the fan/flue/vent counts, so those stay unset
+  (RdSAP Table-5 age defaults — see counts note below).
 
 Either way, an MEV/MVHR cert (`mechanical_ventilation ≠ 0`) is treated as
 **natural** by the affected mappers — wrong §2 ventilation cascade (and heat
@@ -34,14 +37,15 @@ The granular **counts** (fans/flues/vents) are *not* a bug: older RdSAP open-dat
 certs don't lodge them, and the calc correctly uses RdSAP Table-5 age defaults.
 `percent_draughtproofed` is mapped (top-level) and read by the calc.
 
-**Remaining fix (19.0 / 21.0.0):** give them a proper `sap_ventilation`
-construction mirroring 21.0.1. **Calc-facing → validate** with the RdSAP-21.0.1
-corpus (must hold 73.3% / MAE 0.774) plus an **Elmhurst-anchored MEV/MVHR
-`RealCertExpectation`** (the corpus is natural-vent-dominated, so the kind change
-isn't exercised by it). Quantify blast radius: count older-RdSAP certs with
-`mechanical_ventilation ≠ 0`. The 17.1/18.0/20.0.0 fix in this PR is guarded by a
-mapper-level MVHR test + the corpus/mapper-corpus staying green, with the Elmhurst
-MEV/MVHR anchor as the SAP-accuracy fast-follow.
+**19.0 / 21.0.0 fix (done, `feat/rdsap-19-21-ventilation`):** both build
+`SapVentilation(sheltered_sides=…, mechanical_ventilation_kind=…)` mirroring
+21.0.1. Guarded by the extended mapper-level MVHR test + a `sheltered_sides`
+regression, with the corpus (held 73.3% / MAE 0.774 — it's 21.0.1-only so the
+change isn't exercised by it) and the 6002-case mapper-corpus staying green.
+**Outstanding SAP-accuracy fast-follow:** an **Elmhurst-anchored MEV/MVHR
+`RealCertExpectation`** (the corpus is natural-vent-dominated, so the kind
+change isn't exercised by it). **Blast radius (still to quantify):** count
+portfolio-796 certs on schema 19.0 / 21.0.0 with `mechanical_ventilation ≠ 0`.
 
 ## 2. FE "Main Fuel: Unknown" is FE-side, not a Model mapper gap