Methodology · Scenarios
What-if, as a first-class object.
A scenario is a named, validated set of typed overrides against a base plan — retire at 60, save $500 more a month, assume different returns — not a re-typed spreadsheet.
How scenarios work
Typed deltas, re-projected in full.
Typed, validated overrides
The change you make is one of a fixed set of typed deltas — retirement age, monthly contribution, return or inflation assumption, tax rate, income or expense change, account balance, goal target — validated against the base plan. A change that points at nothing, or does nothing, surfaces as a warning rather than being silently dropped.
The whole plan is re-projected
Comparing scenarios re-projects each entire plan server-side — never arithmetic on stale outputs. You get back an input diff (exactly what changed), an outcome diff (the percentile deltas against the base), and per-goal outcome deltas.
Anchored to the base it was built on
Each scenario carries a content hash of the base plan it was authored against, so a comparison run after the underlying plan has changed is caught and flagged — not reported as if it were still current.
Where the engine stops.
The methodology overview lists every known limitation, with the capital-market defaults and how the engine is validated.