Update tools/forecaster.py

tools/forecaster.py

@@ -1,3 +1,5 @@
+# tools/forecaster.py
+
 import pandas as pd
 from statsmodels.tsa.arima.model import ARIMA
 import plotly.graph_objects as go
@@ -5,28 +7,38 @@ import plotly.graph_objects as go
 def forecast_metric_tool(file_path: str, date_col: str, value_col: str):
     """
     Forecast next 3 periods for any numeric metric.
-    Saves PNG and returns forecast DataFrame as text.
+    Saves PNG to /tmp via our safe write monkey-patch, returns forecast table as text.
     """
+    # 1) Load
     df = pd.read_csv(file_path)
 
+    # 2) Parse dates
     try:
         df[date_col] = pd.to_datetime(df[date_col])
     except Exception:
-        return f"❌ '{date_col}' not parseable as dates."
+        return f"❌ Could not parse '{date_col}' as dates."
 
-    if value_col not in df.columns:
-        return f"❌ '{value_col}' column missing."
+    # 3) Coerce metric to numeric, drop invalid
+    df[value_col] = pd.to_numeric(df[value_col], errors="coerce")
+    series = df.set_index(date_col)[value_col].dropna()
 
-    df.set_index(date_col, inplace=True)
-    model = ARIMA(df[value_col], order=(1, 1, 1))
-    model_fit = model.fit()
-    forecast = model_fit.forecast(steps=3)
+    if series.empty:
+        return f"❌ Column '{value_col}' has no valid numeric data after coercion."
 
-    # Plot
+    # 4) Fit ARIMA
+    try:
+        model     = ARIMA(series, order=(1, 1, 1))
+        model_fit = model.fit()
+    except Exception as e:
+        return f"❌ ARIMA fitting failed: {e}"
+
+    # 5) Forecast & plot
+    forecast = model_fit.forecast(steps=3)
     fig = go.Figure()
-    fig.add_scatter(x=df.index, y=df[value_col], mode="lines", name=value_col)
+    fig.add_scatter(x=series.index, y=series, mode="lines", name=value_col)
     fig.add_scatter(x=forecast.index, y=forecast, mode="lines", name="Forecast")
     fig.update_layout(title=f"{value_col} Forecast", template="plotly_dark")
-    fig.write_image("forecast_plot.png")
+    fig.write_image("forecast_plot.png")  # goes into /tmp thanks to our monkey-patch
 
+    # 6) Return textual table
     return forecast.to_frame(name="Forecast").to_string()