WATERFALL

waterfall / bridge. Needs: a start total + signed delta steps; end total is computed, never supplied.

flowbridgevariance-decomposition

DL-01 AGRAW

Use when

explaining how a total moved from A to B through named drivers
cost bridges, budget-to-forecast, headcount walks
3 to 7 delta steps

Do not use when

independent variances with no running total (use CH-DEV-01)
more than 7 steps (aggregate the tail)
any cumulative level would go below zero on the canvas

See instead

deltas are independent, not sequential: CH-DEV-01
composition of a static total: CH-PTW-01

Alternatives

CH-DEV-01 (diverging bar, when steps are independent)

Rules

the end bar is COMPUTED from start + deltas; supplying it is a validation error
increases and decreases colored by semantic roles, totals in ink
delta labels signed (+12 / -6); unit once on the start label
dashed connectors carry the running level between bars
step order is the data's order; the renderer never re-sorts a bridge

Never do this

supplying the end total as data (it must reconcile by construction)
unsigned delta labels
sorting steps by size (a bridge is a narrative, keep the told order)
floating bars without connectors
3D depth

QA before delivering

end bar equals start + sum of deltas
every delta label carries its sign
unit exactly once, on the start label
connectors present between all bars
title states the end-to-end move with a number
source line present bottom-left

Data shape

title	string, action title stating the end-to-end move with a number
eyebrow	string caps, rendered only when the DL chrome asks for it
source	string, rendered bottom-left, always
unit	string, appears once, on the start bar label
start	{label, value}
steps	array of {label, delta} with sign; rendered in given order
end_label	string label for the computed end bar

Sample data (golden)

{
  "title": "Forecast lands 18 points over budget; logistics drives two thirds of the overrun",
  "eyebrow": "COST BRIDGE . JUNE UPDATE",
  "source": "Source: sample dataset v1, 2026-07-12",
  "unit": "pts",
  "start": {
    "label": "Budget",
    "value": 100
  },
  "steps": [
    {
      "label": "Logistics",
      "delta": 12
    },
    {
      "label": "Rework",
      "delta": 8
    },
    {
      "label": "FX",
      "delta": 4
    },
    {
      "label": "Scope savings",
      "delta": -6
    }
  ],
  "end_label": "Forecast"
}