fix(a11y): include leftover-pair evidence in button names

docs/product-technical-gap-baseline.md

@@ -1,5 +1,13 @@
 # Product & Technical Gap Baseline
 
+> Leftover-pair accessible-name overlay: 2026-09-07 KST. Issue #976 stacks
+> onto leftover-map single-writer `#802` at `32f1cda10` so pair-button
+> names include the same finite leftover evidence badges already rendered
+> (`R`, `Y/E`, rank, unexplained, shares, reconstruction, coordinates,
+> distance). Grouping-comparison pair actions stay on `#829`/`#830` and
+> are not expanded here. This branch is Draft; it is not protected-main
+> or independently approved evidence.
+>
 > Exact-head rendered-UX overlay: 2026-08-31 12:16 KST. PR #802
 > implementation revision `1e972d7f6` retains persisted-only `d`, `R̂`, and
 > `e` projection while moving dense segment captions off their plot segments

frontend/src/App.test.tsx

@@ -4175,7 +4175,11 @@ describe("App, authenticated", () => {
     expect(closestPair).toHaveTextContent("R̂ +0.25");
     expect(closestPair).toHaveTextContent("ξ (+0.50, +0.10) ζ (+0.50, −0.02)");
     expect(closestPair).toHaveTextContent("d 0.12");
-    expect(closestPair).toHaveAccessibleName("Open leftover closest pair: Public post · sales-lead");
+    expect(closestPair).toHaveAccessibleName(/Open leftover closest pair: Public post · sales-lead/);
+    expect(closestPair).toHaveAccessibleName(/R \+0\.40/);
+    expect(closestPair).toHaveAccessibleName(/Y 2\.40 · E 2\.00/);
+    expect(closestPair).toHaveAccessibleName(/rank 1/);
+    expect(closestPair).toHaveAccessibleName(/d 0\.12/);
     expect(farthestPair).toHaveTextContent("Farthest leftover: Specification revision requested · negative");
     expect(farthestPair).toHaveTextContent(
       "Leftover map places this post at ξ (+0.90, +0.80) and the criterion at ζ (−0.70, −0.40) after IRT main effects. Open this post to read negative.",

frontend/src/components/LeftoverPairList.test.tsx

@@ -46,9 +46,13 @@ describe("LeftoverPairList", () => {
 
     expect(screen.getByLabelText("Leftover pairs")).toBeInTheDocument();
     const closest = screen.getByRole("button", {
-      name: "Open leftover closest pair: Public post · sales-lead",
+      name: /Open leftover closest pair: Public post · sales-lead/,
     });
     expect(closest).toHaveTextContent("Closest leftover: Public post · sales-lead");
+    expect(closest).toHaveAccessibleName(/R \+0\.40/);
+    expect(closest).toHaveAccessibleName(/Y 2\.40 · E 2\.00/);
+    expect(closest).toHaveAccessibleName(/rank 1/);
+    expect(closest).toHaveAccessibleName(/d 0\.12/);
     expect(closest).toHaveTextContent(
       "Read leftover map rank 1, observed Y 2.40, and expected E 2.00 after IRT main effects, then open this post.",
     );
@@ -58,8 +62,9 @@ describe("LeftoverPairList", () => {
     expect(closest).toHaveTextContent("d 0.12");
 
     const farthest = screen.getByRole("button", {
-      name: "Open leftover farthest pair: Specification revision requested · negative",
+      name: /Open leftover farthest pair: Specification revision requested · negative/,
     });
+    expect(farthest).toHaveAccessibleName(/R −1\.10/);
     expect(farthest).toHaveTextContent("R −1.10");
     expect(farthest).toHaveTextContent("Y 0.90 · E 2.00");
     expect(farthest).toHaveTextContent("rank 1");
@@ -78,6 +83,31 @@ describe("LeftoverPairList", () => {
     );
   });
 
+  it("omits non-finite leftover residual and distance from the pair action", () => {
+    render(
+      <LeftoverPairList
+        pairs={[
+          {
+            ...PAIRS[0],
+            leftover_residual: Number.NaN,
+            leftover_distance: Number.NaN,
+          },
+        ]}
+        criterionLabel={criterionLabel}
+        onSelectPost={vi.fn()}
+      />,
+    );
+
+    const closest = screen.getByRole("button", {
+      name: /Open leftover closest pair: Public post · sales-lead/,
+    });
+    expect(closest).toHaveAccessibleName(/rank 1/);
+    expect(closest).not.toHaveAccessibleName(/R /);
+    expect(closest).not.toHaveAccessibleName(/\bd /);
+    expect(closest).not.toHaveTextContent("R —");
+    expect(closest).not.toHaveTextContent("d NaN");
+  });
+
   it("keeps residual guidance for an older payload without rank or Y/E", () => {
     render(
       <LeftoverPairList
@@ -148,8 +178,11 @@ describe("LeftoverPairList", () => {
     );
 
     const closest = screen.getByRole("button", {
-      name: "Open leftover closest pair: Public post · sales-lead",
+      name: /Open leftover closest pair: Public post · sales-lead/,
     });
+    expect(closest).toHaveAccessibleName(/R \+0\.40/);
+    expect(closest).toHaveAccessibleName(/R̂²\/R² 0\.76/);
+    expect(closest).toHaveAccessibleName(/ξ \(\+0\.50, \+0\.10\) ζ \(\+0\.50, −0\.02\)/);
     expect(closest).toHaveTextContent(
       "Leftover map places this post at ξ (+0.50, +0.10) and the criterion at ζ (+0.50, −0.02) after IRT main effects. Open this post to read sales-lead.",
     );

frontend/src/components/LeftoverPairList.tsx

@@ -33,6 +33,7 @@ import {
   formatLeftoverMapUnexplainedShare,
   LEFTOVER_MAP_UNEXPLAINED_SHARE_ACTION,
 } from "../leftoverMapUnexplainedShare";
+import { formatLeftoverMapDistance } from "../leftoverMapPlotLayout";
 import { LeftoverMapPlot } from "./LeftoverMapPlot";
 
 export type LeftoverPairListProps = {
@@ -42,6 +43,11 @@ export type LeftoverPairListProps = {
   onSelectPost: (pair: LeftoverPair) => void;
 };
 
+/** Join finite leftover evidence already selected by the pair-row formatters. */
+function leftoverPairAccessibleName(parts: Array<string | null | undefined>): string {
+  return parts.filter((part): part is string => typeof part === "string" && part.length > 0).join(" ");
+}
+
 /**
  * Closest and farthest leftover post–criterion pairs after IRT main effects.
  *
@@ -89,6 +95,8 @@ export function LeftoverPairList({
           pair.pair_kind === "farthest" ? t("Farthest leftover") : t("Closest leftover");
         const criterion = criterionLabel(pair.criterion_code);
         const residual = formatLeftoverResidual(pair.leftover_residual);
+        const residualBadge = Number.isFinite(pair.leftover_residual) ? `R ${residual}` : null;
+        const distanceBadge = formatLeftoverMapDistance(pair.leftover_distance);
         const observedExpected = formatLeftoverObservedExpected(
           pair.observed_response,
           pair.expected_response,
@@ -216,19 +224,31 @@ export function LeftoverPairList({
             <button
               type="button"
               className="post-list-item"
-              aria-label={tf("Open leftover {kind} pair: {title} · {criterion}", {
-                kind: pair.pair_kind,
-                title: pair.post_title,
-                criterion,
-              })}
+              aria-label={leftoverPairAccessibleName([
+                tf("Open leftover {kind} pair: {title} · {criterion}", {
+                  kind: pair.pair_kind,
+                  title: pair.post_title,
+                  criterion,
+                }),
+                residualBadge,
+                observedExpected,
+                rankBadge,
+                unexplained,
+                unexplainedShareBadge,
+                explainedShareBadge,
+                crossShareBadge,
+                reconstruction,
+                coordinatesBadge,
+                distanceBadge,
+              ])}
               title={t("Open this post so the leftover criterion is current in Post quality.")}
               onClick={() => onSelectPost(pair)}
             >
               <span className="ticket-title">
                 {kindLabel}: {pair.post_title} · {criterion}
               </span>
               <span className="post-badge">{nextAction}</span>
-              <span className="post-badge">R {residual}</span>
+              {residualBadge ? <span className="post-badge">{residualBadge}</span> : null}
               {observedExpected ? <span className="post-badge">{observedExpected}</span> : null}
               {rankBadge ? <span className="post-badge">{rankBadge}</span> : null}
               {unexplained ? <span className="post-badge">{unexplained}</span> : null}
@@ -241,7 +261,7 @@ export function LeftoverPairList({
               {crossShareBadge ? <span className="post-badge">{crossShareBadge}</span> : null}
               {reconstruction ? <span className="post-badge">{reconstruction}</span> : null}
               {coordinatesBadge ? <span className="post-badge">{coordinatesBadge}</span> : null}
-              <span className="post-badge">d {pair.leftover_distance.toFixed(2)}</span>
+              {distanceBadge ? <span className="post-badge">{distanceBadge}</span> : null}
             </button>
           </li>
         );