improve model training

docs/rain_prediction.md

@@ -43,6 +43,7 @@ pip install -r scripts/requirements.txt
   `predictions_rain_1h`.
 - `scripts/run_rain_ml_worker.py`: long-running worker for periodic training + prediction.
 - `scripts/check_rain_pipeline_health.py`: freshness/failure check for alerting.
+- `scripts/recommend_rain_model.py`: rank saved training reports and recommend a deployment candidate.
 
 Feature-set options:
 - `baseline`: original 5 local observation features.
@@ -181,6 +182,22 @@ python scripts/train_rain_model.py \
   --model-card-out "models/model_card_{model_version}.md"
 ```
 
+### 3f) Walk-forward threshold policy (more temporally robust alert threshold)
+```sh
+python scripts/train_rain_model.py \
+  --site "home" \
+  --start "2026-02-01T00:00:00Z" \
+  --end "2026-03-03T23:55:00Z" \
+  --feature-set "extended" \
+  --model-family "auto" \
+  --forecast-model "ecmwf" \
+  --threshold-policy "walk_forward" \
+  --walk-forward-folds 4 \
+  --model-version "rain-auto-v1-extended-wf-threshold" \
+  --out "models/rain_model_auto.pkl" \
+  --report-out "models/rain_model_report_auto.json"
+```
+
 ### 4) Run inference and store prediction
 ```sh
 python scripts/predict_rain_model.py \
@@ -200,7 +217,7 @@ The `rainml` service in `docker-compose.yml` now runs:
 - periodic retraining (default every 24 hours)
 - periodic prediction writes (default every 10 minutes)
 - configurable tuning/calibration behavior (`RAIN_TUNE_HYPERPARAMETERS`,
-  `RAIN_MAX_HYPERPARAM_TRIALS`, `RAIN_CALIBRATION_METHODS`)
+  `RAIN_MAX_HYPERPARAM_TRIALS`, `RAIN_CALIBRATION_METHODS`, `RAIN_THRESHOLD_POLICY`)
 - graceful gap handling for temporary source outages (`RAIN_ALLOW_EMPTY_DATA=true`)
 - automatic rollback path for last-known-good model (`RAIN_MODEL_BACKUP_PATH`)
 - optional model-card output (`RAIN_MODEL_CARD_PATH`)
@@ -222,6 +239,15 @@ docker compose logs -f rainml
 - Prediction rows: `predictions_rain_1h` (probability + threshold decision + realized
   outcome fields once available)
 
+### 7) Recommend deploy candidate from saved reports
+```sh
+python scripts/recommend_rain_model.py \
+  --reports-glob "models/rain_model_report*.json" \
+  --require-walk-forward \
+  --top-k 5 \
+  --json-out "models/rain_model_recommendation.json"
+```
+
 ## Model Features (v1 baseline)
 - `pressure_trend_1h`
 - `humidity`