Fix contribution compounding: monthly contributions are now added to
asset values before each GBM step so they grow with market returns,
rather than being summed as a static lump at each period.
Add year-by-year milestone table below the fan chart showing P10/P50/P90
portfolio values at each annual checkpoint up to the selected horizon.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Replaces unused Prophet dependency (unrunnable without cmdstan) with
SARIMA (statsmodels SARIMAX) as the primary spending forecast algorithm.
Strategy: SARIMA(1,1,1)(1,0,1,12) for 12+ months of data, ARIMA(1,1,1)
for 6-11 months, Holt-Winters for 3-5 months, simple average below that.
Adds 95% confidence bands (1.96σ) alongside existing 80% (1.28σ).
Extends forecast horizon from 3 to 6 months and actuals display from
6 to 12 months. Each category now carries an algorithm field surfaced
as a badge in the UI. Frontend chart shows both confidence tiers as
stacked bar overlays with a 3-month summary grid below.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Phase 1 — Budget Forecast: adds a dedicated first-class tab showing all
monthly budgets with velocity (£/day), forecast month-end total, dual
progress bars, and colour-coded overspend probability badges. Summary
bar shows budgets tracked / at-risk count / total forecast overspend.
Removes the old BudgetAlerts widget embedded in the Spending tab.
Phase 2 — Cash Flow: incorporates known recurring transactions into the
30-day projection (outflows hit on their predicted dates rather than
being smeared as averages), adds sqrt-of-time confidence bands to the
chart, and shows an upcoming recurring payments list with at-risk
highlighting for payments falling on or after the first negative-balance day.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
