Complete. The forecast change note is written to `output/drivers-note.md`. 

**Key findings:**
- EBITDA declined ($149K) or (32.9%) from Prior to Current
- **Active customers** fell 2 (46→44) across all 12 months, driving ($133K) of the decline
- **Headcount** grew 0.75 FTEs over 9 months, driving ($54K) of additional loss
- **Gross margin** improved from 26.2% to 26.6%, offsetting $39K of these losses
- The note asks for documented assumptions supporting the customer loss, headcount growth amid declining customers, and margin expansion