From 395dd95202652c3be9833fe35457bd5dd89db073 Mon Sep 17 00:00:00 2001
From: David Trimmer <david@policyengine.org>
Date: Tue, 7 Jul 2026 10:02:33 -0400
Subject: [PATCH] Format rate-type validation rows as percentages

Populace PR #348 adds Census state SPM poverty-rate backtests whose level
rows carry unit: "percent" with decimal-fraction values. Thread the unit
through the payload parser and row types, and format value cells with a
shared fmtUnitValue (0.134 -> "13.4%") in the reforms and staging views.
Rows without a unit keep the USD formatting, so pre-#348 payloads render
unchanged.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
---
 .../components/populace/populace-reforms-view.tsx  |  6 +++---
 .../components/populace/populace-staging-view.tsx  |  5 +++--
 frontend/components/shared/format.ts               | 14 ++++++++++++++
 frontend/lib/api/hooks/use-populace.ts             |  2 ++
 frontend/lib/populace/reforms.ts                   |  5 +++++
 5 files changed, 27 insertions(+), 5 deletions(-)

diff --git a/frontend/components/populace/populace-reforms-view.tsx b/frontend/components/populace/populace-reforms-view.tsx
index 1935160..24e3bd1 100644
--- a/frontend/components/populace/populace-reforms-view.tsx
+++ b/frontend/components/populace/populace-reforms-view.tsx
@@ -3,7 +3,7 @@
 import { Fragment, useEffect, useMemo, useState } from "react";
 
 import { EmptyState } from "@/components/shared/empty-state";
-import { fmt, fmtMoney, releaseLabel } from "@/components/shared/format";
+import { fmt, fmtMoney, fmtUnitValue, releaseLabel } from "@/components/shared/format";
 import { KpiCard } from "@/components/shared/kpi-card";
 import { LoadingBlock } from "@/components/shared/LoadingBlock";
 import { PageHeader } from "@/components/shared/page-header";
@@ -253,10 +253,10 @@ function ReformTable({
                     </div>
                   </td>
                   <td className="whitespace-nowrap px-3 py-1.5 text-right tabular-nums">
-                    {fmtMoney(row.jct_score)}
+                    {fmtUnitValue(row.jct_score, row.unit)}
                   </td>
                   <td className="whitespace-nowrap px-3 py-1.5 text-right tabular-nums">
-                    {fmtMoney(row.populace_estimate)}
+                    {fmtUnitValue(row.populace_estimate, row.unit)}
                   </td>
                   <td className="whitespace-nowrap px-3 py-1.5">
                     <ErrorCell absRel={row.abs_relative_error} />
diff --git a/frontend/components/populace/populace-staging-view.tsx b/frontend/components/populace/populace-staging-view.tsx
index 33809c9..28424b8 100644
--- a/frontend/components/populace/populace-staging-view.tsx
+++ b/frontend/components/populace/populace-staging-view.tsx
@@ -4,6 +4,7 @@ import { useEffect, useMemo, useState } from "react";
 
 import { EmptyState } from "@/components/shared/empty-state";
 import {
+  fmtUnitValue,
   fmt,
   fmtCompact,
   fmtMoney,
@@ -245,10 +246,10 @@ function ReformValidationTable({
                   </div>
                 </td>
                 <td className="whitespace-nowrap px-3 py-2 text-right tabular-nums">
-                  {fmtMoney(row.jct_score)}
+                  {fmtUnitValue(row.jct_score, row.unit)}
                 </td>
                 <td className="whitespace-nowrap px-3 py-2 text-right tabular-nums">
-                  {fmtMoney(row.populace_estimate)}
+                  {fmtUnitValue(row.populace_estimate, row.unit)}
                 </td>
                 <td
                   className={`whitespace-nowrap px-3 py-2 text-right tabular-nums ${
diff --git a/frontend/components/shared/format.ts b/frontend/components/shared/format.ts
index a175612..cc5caa9 100644
--- a/frontend/components/shared/format.ts
+++ b/frontend/components/shared/format.ts
@@ -73,6 +73,20 @@ export function fmtCompact(value: number | null | undefined): string {
   return `${sign}${abs.toFixed(0)}`;
 }
 
+/** Format a validation value by its payload unit: "percent" rows hold
+ *  decimal fractions (0.134 -> "13.4%"); everything else is USD. */
+export function fmtUnitValue(
+  value: number | null | undefined,
+  unit: string | null | undefined,
+): string {
+  if (unit === "percent") {
+    return value == null || !Number.isFinite(value)
+      ? "—"
+      : `${(value * 100).toFixed(1)}%`;
+  }
+  return fmtMoney(value);
+}
+
 export function fmtMoney(value: number | null | undefined): string {
   if (value == null || !Number.isFinite(value)) return "—";
   const abs = Math.abs(value);
diff --git a/frontend/lib/api/hooks/use-populace.ts b/frontend/lib/api/hooks/use-populace.ts
index 3168c7d..dbfcc93 100644
--- a/frontend/lib/api/hooks/use-populace.ts
+++ b/frontend/lib/api/hooks/use-populace.ts
@@ -489,6 +489,8 @@ export interface ReformValidationRow {
   populace_estimate?: number | null;
   populace_window?: string | null;
   populace_annual?: Record<string, number> | null;
+  /** "percent" for rate backtests (decimal fractions); USD otherwise. */
+  unit?: "currency-USD" | "percent" | null;
   abs_error?: number | null;
   relative_error?: number | null;
   abs_relative_error?: number | null;
diff --git a/frontend/lib/populace/reforms.ts b/frontend/lib/populace/reforms.ts
index 8c8c4e4..b443f00 100644
--- a/frontend/lib/populace/reforms.ts
+++ b/frontend/lib/populace/reforms.ts
@@ -93,6 +93,10 @@ export interface ReformValidationRow {
   populace_estimate: number | null;
   populace_window: string | null;
   populace_annual: Record<string, number> | null;
+  // Value unit: "currency-USD" (default) or "percent" for rate backtests
+  // (e.g. Census state SPM poverty rates, where the values are decimal
+  // fractions like 0.134 rather than dollars).
+  unit: "currency-USD" | "percent";
   // Derived (relative to jct_score, i.e. the FY2027 benchmark where available).
   abs_error: number | null; // populace − jct (USD)
   relative_error: number | null; // (populace − jct) / |jct|
@@ -157,6 +161,7 @@ function enrichReform(raw: JsonObject): ReformValidationRow {
     description: stringOrNull(raw.description),
     in_sample: raw.in_sample === true,
     period: numberOrNull(raw.period),
+    unit: raw.unit === "percent" ? "percent" : "currency-USD",
     jct_score: benchmark,
     jct_score_fy2026: jctFy2026,
     jct_score_type: stringOrNull(jct.score_type),