Explain silent no-op society-wide reports with an informational callout

[MaxGhenis]

What

The society-wide report output now shows an informational callout above the result cards when a reform is a complete no-op — every output is identical to current law. Previously the page rendered "No change" everywhere (budget, deciles, winners/losers at 100% no change, poverty, inequality) with no explanation, so users could not tell a genuine zero-impact reform from one that never touched anything in effect that year.

This is the "exact-zero callout" from #1116 (suggestion 1). Motivating repro: an Oregon Kids' Credit expansion modeled for 2029, after the credit sunsets (HB 3235) — editing its amount for 2029+ changes nothing, and the null result read as user error.

Why

Silent no-ops are indistinguishable from real zero-impact reforms and from plain start-date / simulated-year mismatches. The callout names the likely cause and the year to check.

Detection rule

isSocietyWideReportNoOp(output) returns true only for an exact whole-report no-op — all four must hold:

• budget.budgetary_impact exactly 0
• budget.benefit_spending_impact exactly 0
• budget.tax_revenue_impact exactly 0
• intra_decile.all['No change'] exactly 1 (100% of the population unchanged)

Missing or malformed fields are treated as NOT a no-op, and the function never throws. Both US and UK report shapes are handled (the checked fields are identical across them). Because all four conditions are required, a single zero panel — e.g. a revenue-neutral reform that still moves money between households — does not trigger the callout.

Callout

Reuses the repo's Alert idiom (@/components/ui, informational teal-bordered styling with IconInfoCircle, matching FloatingAlert's info type). Copy is sentence case, with <year> from the report context via useReportYear():

• Title: "This reform doesn't change any policy in <year>"
• Body: "Every output is identical to current law. Check that your parameters' start dates cover <year>, and that the programs you edited are in effect that year — some credits phase in later or expire."

Files

• app/src/utils/isSocietyWideReportNoOp.ts — pure detection util
• app/src/pages/report-output/NoOpReportCallout.tsx — the callout component
• app/src/pages/report-output/SocietyWideOverview.tsx — renders the callout above the card grid when the util returns true (the large line count is prettier re-indentation from the new Stack wrapper; the logical change is ~7 lines — see the git diff -w)
• app/src/pages/report-output/SocietyWideOverview.story.tsx — adds a CompleteNoOp story (plus the CountryProvider / ReportYearProvider decorators it needs to render)
• changelog_entry.yaml — user-facing fixed line

Test coverage

• Util unit tests (app/src/tests/unit/utils/isSocietyWideReportNoOp.test.ts): all-zero US → true; all-zero UK → true; tiny nonzero budgetary / benefit-spending / tax-revenue → false; 99.9% no change → false; revenue-neutral with real winners and losers → false; null / undefined / missing budget / missing intra_decile / missing "No change" / non-numeric → false.
• Component tests (SocietyWideOverview.test.tsx): callout renders with the interpolated year on an all-zero fixture; falls back to a generic year phrase when there is no report-year context; absent on the default (nonzero) fixture; absent on a revenue-neutral fixture.

Verification

• vitest (util + component suites): 36 passed
• tsc --noEmit clean; eslint . --cache 0 warnings; prettier --check clean
• Visual: rendered the CompleteNoOp Storybook story and confirmed the callout appears above the cards with the informational styling and the 2029 year interpolated.

Fixes #1116

🤖 Generated with Claude Code

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated (UTC)
policyengine-app-v2	Ready	Preview, Comment	Jul 17, 2026 9:51pm
policyengine-calculator	Ready	Preview, Comment	Jul 17, 2026 9:51pm
policyengine-calculator-next	Ready	Preview, Comment	Jul 17, 2026 9:51pm
policyengine-website	Ready	Preview, Comment	Jul 17, 2026 9:51pm