Implemented the next 4h-plan phase: dual-run support + explicit cutover gate.

docs/rain_model_runbook.md

@@ -39,8 +39,8 @@ scripts/rainml_py.sh scripts/train_rain_model.py \
   --threshold-policy "walk_forward" \
   --walk-forward-folds 4 \
   --model-version "rain-auto-v2-extended-4h" \
-  --out "models/rain_model.pkl" \
-  --report-out "models/rain_model_report.json" \
+  --out "models/rain_model_4h.pkl" \
+  --report-out "models/rain_model_report_4h.json" \
   --model-card-out "models/model_card_{model_version}.md" \
   --dataset-out "models/datasets/rain_dataset_{model_version}_{feature_set}.csv"
 ```
@@ -61,7 +61,7 @@ Review in report:
 ```sh
 scripts/rainml_py.sh scripts/predict_rain_model.py \
   --site home \
-  --model-path "models/rain_model.pkl" \
+  --model-path "models/rain_model_4h.pkl" \
   --model-name "rain_next_4h" \
   --horizon-hours 4 \
   --dry-run
@@ -72,7 +72,7 @@ scripts/rainml_py.sh scripts/predict_rain_model.py \
 ```sh
 scripts/rainml_py.sh scripts/predict_rain_model.py \
   --site home \
-  --model-path "models/rain_model.pkl" \
+  --model-path "models/rain_model_4h.pkl" \
   --model-name "rain_next_4h" \
   --horizon-hours 4
 ```
@@ -155,6 +155,14 @@ The script exits non-zero on failure, so it can directly drive alerting.
 - `RAIN_MODEL_BACKUP_PATH`
 - `RAIN_MODEL_CARD_PATH`
 
+Dual-run note:
+- `rainml` is configured as 4-hour model training/inference with dedicated artifact paths.
+- `rainml_1h` is available as an optional shadow/baseline service via profile `shadow`.
+- Start both (4h + 1h shadow):
+  `docker compose --profile shadow up -d rainml rainml_1h`
+- Run one-off script against the 1h service:
+  `RAINML_PY_SERVICE=rainml_1h scripts/rainml_py.sh scripts/train_rain_model.py ...`
+
 Recommended production defaults:
 - Enable tuning daily or weekly (`RAIN_TUNE_HYPERPARAMETERS=true`)
 - Set `RAIN_THRESHOLD_POLICY=walk_forward` with `RAIN_WALK_FORWARD_FOLDS=4` for temporally robust threshold selection
@@ -217,6 +225,19 @@ scripts/rainml_py.sh scripts/compare_rain_reports.py \
   --baseline "models/rain_model_report_1h.json" \
   --candidate "models/rain_model_report_4h.json"
 ```
+
+4b. Apply an explicit cutover gate (exit code 0 = pass):
+
+```sh
+scripts/rainml_py.sh scripts/check_rain_cutover_gate.py \
+  --baseline "models/rain_model_report_1h.json" \
+  --candidate "models/rain_model_report_4h.json" \
+  --min-candidate-precision 0.60 \
+  --max-precision-drop 0.05 \
+  --max-pr-auc-drop 0.05 \
+  --max-roc-auc-drop 0.05 \
+  --max-brier-increase 0.03
+```
 5. Run dry-run inference, then live inference with 4h model name/horizon:
 
 ```sh