diff --git a/AGENTS.md b/AGENTS.md
index 805c548ed..230ef3aad 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -540,3 +540,5 @@ published beside the ontology.
 ADR 0294 keeps grouping-comparison incomplete-item coverage in the LineageWeave read-model boundary: consume only authorization-filtered persisted coverage for a full grouping, omit partial visibility, and never recompute psychometrics in the client.
 
 ADR 0295 keeps grouping-comparison reconstruction in the LineageWeave read-model/UI boundary: format only persisted `R̂`, expose the value in the pair button accessible name, and never derive psychometric reconstruction from UI-visible proxies.
+
+ADR 0296 adds persisted grouping-comparison explained-leftover share `e` in the LineageWeave read-model/UI boundary: expose it in the pair button accessible name, keep the duplicate visible badge presentation-only, and never derive or clamp psychometric values.
diff --git a/ARCHITECTURE.md b/ARCHITECTURE.md
index 98c0c7669..f16d44bed 100644
--- a/ARCHITECTURE.md
+++ b/ARCHITECTURE.md
@@ -1093,3 +1093,5 @@ the rare creation branch serializes.
 ADR 0294 adds persisted incomplete-item coverage to grouping comparison presentation while the API remains the full-group visibility authority; the frontend formats only an admitted persisted count.
 
 ADR 0295 adds persisted `R̂` to grouping-comparison pair buttons. The explicit button accessible name carries the reconstruction label/value; the visible duplicate badge is presentation-only. Psychometric computation remains owned by fast-mlsirm.
+
+ADR 0296 adds persisted explained-leftover share `e = R̂²/R²` to grouping-comparison pair actions; the button accessible name is authoritative for assistive technology and fast-mlsirm remains psychometric owner.
diff --git a/CHANGELOG.d/2.53.0-leftover-map-compare-explained-share.md b/CHANGELOG.d/2.53.0-leftover-map-compare-explained-share.md
new file mode 100644
index 000000000..11013ecb4
--- /dev/null
+++ b/CHANGELOG.d/2.53.0-leftover-map-compare-explained-share.md
@@ -0,0 +1,5 @@
+## 2.53.0 — Grouping comparison explained-leftover share
+
+- Show persisted `e = R̂²/R²` on grouping-comparison pair buttons (ADR 0296).
+- Put the localized metric/value in the button accessible name; the duplicate visible badge is `aria-hidden`.
+- Missing/non-finite values omit only this metric; zero and values above 1 are preserved and no proxy is derived.
diff --git a/CHANGELOG.md b/CHANGELOG.md
index f34327ac3..5cffe6075 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,8 @@ All notable changes to this project are documented here. Format follows
 
 ### Added
 
+- Grouping comparison pair buttons now expose persisted explained-leftover share `e = R̂²/R²` (ADR 0296 / v2.53.0). The visible duplicate badge is accessibility-hidden while the actionable button name includes the localized label and formatted persisted value. Missing/non-finite `e` omits only the suffix; finite zero and values above 1 remain explicit without clamping or client-side derivation.
+
 - Grouping comparison leftover-pair buttons now expose persisted leftover-map reconstruction `R̂` (ADR 0295 / v2.52.0). The visible badge is decorative to accessibility APIs; the button accessible name carries the reconstruction label and value, so the explicit button `aria-label` cannot suppress the metric. Missing/non-finite `R̂` omits only that value and no client-side proxy is invented.
 
 - Grouping comparison rows now show persisted leftover-map incomplete-item count through `leftoverMapIncompleteItemCount` (ADR 0294 / v2.51.0) only for fully caller-visible persisted groupings. Partial visibility remains omitted by the API; valid zero stays visible, and the UI never derives dropped criteria from scored-minus-used.
diff --git a/CLAUDE.md b/CLAUDE.md
index 00cfe1087..a4d4ece4e 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -61,3 +61,5 @@ here.
 ADR 0294 is the Proposed grouping-comparison incomplete-item presentation contract; preserve server-side full-group visibility gating and do not infer dropped criteria in the frontend.
 
 ADR 0295 is the Proposed grouping-comparison reconstruction contract: persisted `R̂` only, no client inference, accessible-name exposure required despite the button's explicit aria-label.
+
+ADR 0296 is the Proposed grouping-comparison explained-share contract: persisted `e` only, accessible-name exposure required, no client derivation or clamping.
diff --git a/docs/adr/0296-leftover-map-compare-explained-share.md b/docs/adr/0296-leftover-map-compare-explained-share.md
new file mode 100644
index 000000000..a99daad79
--- /dev/null
+++ b/docs/adr/0296-leftover-map-compare-explained-share.md
@@ -0,0 +1,11 @@
+# ADR 0296 — Grouping comparison explained-leftover share
+
+**Decision status:** Proposed
+
+## Problem
+The serialized comparison surface omits persisted explained-leftover share `e = R̂²/R²`. The historical implementation rendered a descendant badge inside a button with an explicit accessible name, so the visible metric was not reliably announced as part of the action.
+
+## Decision
+Format only persisted `leftover_map_explained_share` through `formatLeftoverMapExplainedShare`. Append the localized label and formatted value to the pair button accessible name, and mark the duplicate visible badge `aria-hidden`. Missing/non-finite values omit only this suffix; finite zero and values above 1 remain explicit. Never derive or clamp `e` from `R̂`, `R`, distance, coordinates, residuals, rank, coverage, or visible-subset proxies. fast-mlsirm remains psychometric owner.
+
+This ADR remains Proposed while Draft. Acceptance requires current-head hosted tests, rendered keyboard/screen-reader/a11y evidence, canonical eight-locale ledger convergence, independent approval, and normal protected-branch merge.
diff --git a/docs/product-technical-gap-baseline.md b/docs/product-technical-gap-baseline.md
index 76c6db089..9b2d3acea 100644
--- a/docs/product-technical-gap-baseline.md
+++ b/docs/product-technical-gap-baseline.md
@@ -1397,3 +1397,7 @@ Exact parent `#824@499d653ed6e9206249e3f3a07518ad3fc01f14bd` lacks the grouping-
 ### 2026-09-07 — #826 exact-parent reconstruction candidate
 
 Exact parent `#825@b73b10e3079e77f3e62235b2b709dc8a3f450292` omits persisted `R̂` from grouping-comparison pair rows. ADR 0295 / v2.52.0 restores that valid read-model delta and repairs the historical accessibility defect by carrying the label/value in the button accessible name. Candidate evidence is not protected-main/release evidence; current-head browser/screen-reader/a11y, canonical eight-locale ledger consumption, independent review, and normal protected merge remain outstanding.
+
+### 2026-09-07 — #827 exact-parent reconstruction candidate
+
+Exact parent `#826@66a7750a10ad0e9526716d382707f99528a75d90` omits persisted grouping-comparison explained-leftover share. ADR 0296 / v2.53.0 restores that valid delta and fixes its historical accessible-name defect. Candidate evidence is not protected-main/release evidence; current-head browser/screen-reader/a11y, canonical eight-locale ledger consumption, independent review, and normal protected merge remain outstanding.
diff --git a/frontend/package.json b/frontend/package.json
index 10d0e822c..ff2d6a69f 100644
--- a/frontend/package.json
+++ b/frontend/package.json
@@ -1,7 +1,7 @@
 {
   "name": "frontend",
   "private": true,
-  "version": "2.52.0",
+  "version": "2.53.0",
   "type": "module",
   "scripts": {
     "dev": "vite",
diff --git a/frontend/src/App.test.tsx b/frontend/src/App.test.tsx
index 49dedd06e..ff0154e28 100644
--- a/frontend/src/App.test.tsx
+++ b/frontend/src/App.test.tsx
@@ -923,6 +923,7 @@ describe("App, authenticated", () => {
                     leftover_distance: 0.12,
                     leftover_residual: 0.4,
                     leftover_map_reconstruction: 0.248,
+                    leftover_map_explained_share: 0.76,
                   },
                 ],
                 leftover_map_coverage: {
@@ -4342,6 +4343,10 @@ describe("App, authenticated", () => {
       name: /open leftover closest pair from comparison: public post.*leftover map comparison reconstruction R̂ \+0\.25/i,
     });
     expect(reconstructionPair).toHaveTextContent("R̂ +0.25");
+    const explainedSharePair = screen.getByRole("button", {
+      name: /open leftover closest pair from comparison: public post.*leftover map comparison reconstruction R̂ \+0\.25.*leftover map comparison explained leftover share R̂²\/R² 0\.76/i,
+    });
+    expect(explainedSharePair).toHaveTextContent("R̂²/R² 0.76");
     await waitFor(() =>
       expect(fetchMock).toHaveBeenCalledWith(
         expect.stringContaining("/api/reports/thread_group/2026-W02"),
diff --git a/frontend/src/App.tsx b/frontend/src/App.tsx
index 2d4724e72..4d249f852 100644
--- a/frontend/src/App.tsx
+++ b/frontend/src/App.tsx
@@ -147,6 +147,10 @@ import {
   formatLeftoverMapReconstruction,
   LEFTOVER_MAP_COMPARE_RECONSTRUCTION_LABEL,
 } from "./leftoverMapReconstruction";
+import {
+  formatLeftoverMapExplainedShare,
+  LEFTOVER_MAP_COMPARE_EXPLAINED_SHARE_LABEL,
+} from "./leftoverMapExplainedShare";
 import "./App.css";
 
 const AdminPanel = lazy(() => import("./components/AdminPanel").then((module) => ({ default: module.AdminPanel })));
@@ -4073,10 +4077,17 @@ function ReportsPanel({
                     const reconstruction = formatLeftoverMapReconstruction(
                       pair.leftover_map_reconstruction,
                     );
+                    const explainedShare = formatLeftoverMapExplainedShare(
+                      pair.leftover_map_explained_share,
+                    );
                     const pairAccessibleName = `Open leftover ${pair.pair_kind} pair from comparison: ${pair.post_title} · ${criterion}${
                       reconstruction
                         ? ` · ${t(LEFTOVER_MAP_COMPARE_RECONSTRUCTION_LABEL)} ${reconstruction}`
                         : ""
+                    }${
+                      explainedShare
+                        ? ` · ${t(LEFTOVER_MAP_COMPARE_EXPLAINED_SHARE_LABEL)} ${explainedShare}`
+                        : ""
                     }`;
                     return (
                       <li
@@ -4109,6 +4120,11 @@ function ReportsPanel({
                               {reconstruction}
                             </span>
                           ) : null}
+                          {explainedShare ? (
+                            <span className="post-badge" aria-hidden="true">
+                              {explainedShare}
+                            </span>
+                          ) : null}
                         </button>
                       </li>
                     );
diff --git a/frontend/src/i18n.test.ts b/frontend/src/i18n.test.ts
index 53568b6cc..d75abb6c9 100644
--- a/frontend/src/i18n.test.ts
+++ b/frontend/src/i18n.test.ts
@@ -85,6 +85,7 @@ describe("i18n", () => {
     "Leftover map comparison incomplete posts",
     "Leftover map comparison incomplete items",
     "Leftover map comparison reconstruction",
+    "Leftover map comparison explained leftover share",
     "Leftover-map graphic item coverage",
     "Leftover map item coverage",
     "Leftover map incomplete posts",
diff --git a/frontend/src/i18n.ts b/frontend/src/i18n.ts
index 41cf88f39..3a1931720 100644
--- a/frontend/src/i18n.ts
+++ b/frontend/src/i18n.ts
@@ -273,6 +273,7 @@ const TRANSLATIONS: Partial<Record<Locale, Record<string, string>>> = {
     "Leftover map comparison incomplete posts": "잔여 지도 비교 불완전 글",
     "Leftover map comparison incomplete items": "잔여 지도 비교 불완전 기준",
     "Leftover map comparison reconstruction": "잔여 지도 비교 재구성",
+    "Leftover map comparison explained leftover share": "잔여 지도 비교 설명 잔여 비율",
     "Leftover map item coverage": "잔여 지도 기준 포함 범위",
     "Leftover map incomplete posts": "잔여 지도 불완전 글",
     "Leftover map incomplete items": "잔여 지도 불완전 기준",
@@ -887,6 +888,7 @@ const TRANSLATIONS: Partial<Record<Locale, Record<string, string>>> = {
     "Leftover map comparison incomplete posts": "残差地图比较不完整帖文",
     "Leftover map comparison incomplete items": "残差地图比较不完整准则",
     "Leftover map comparison reconstruction": "残差地图比较重建",
+    "Leftover map comparison explained leftover share": "残差地图比较已解释残差占比",
     "Leftover map item coverage": "残差地图准则覆盖范围",
     "Leftover map incomplete posts": "残差地图不完整帖文",
     "Leftover map incomplete items": "残差地图不完整准则",
@@ -1522,6 +1524,7 @@ const TRANSLATIONS: Partial<Record<Locale, Record<string, string>>> = {
     "Leftover map comparison incomplete posts": "残差マップの比較不完全投稿",
     "Leftover map comparison incomplete items": "残差マップの比較不完全基準",
     "Leftover map comparison reconstruction": "残差マップの比較再構成",
+    "Leftover map comparison explained leftover share": "残差マップの比較説明済み残差比率",
     "Leftover map item coverage": "残差マップの基準対象範囲",
     "Leftover map incomplete posts": "残差マップの不完全投稿",
     "Leftover map incomplete items": "残差マップの不完全基準",
@@ -2136,6 +2139,7 @@ const TRANSLATIONS: Partial<Record<Locale, Record<string, string>>> = {
     "Leftover map comparison incomplete posts": "Bài không đầy đủ so sánh trên bản đồ phần dư",
     "Leftover map comparison incomplete items": "Tiêu chí không đầy đủ so sánh trên bản đồ phần dư",
     "Leftover map comparison reconstruction": "Tái dựng so sánh bản đồ phần dư",
+    "Leftover map comparison explained leftover share": "Tỷ phần phần dư được giải thích khi so sánh bản đồ phần dư",
     "Leftover map item coverage": "Phạm vi tiêu chí bản đồ phần dư",
     "Leftover map incomplete posts": "Bài không đầy đủ trên bản đồ phần dư",
     "Leftover map incomplete items": "Tiêu chí không đầy đủ trên bản đồ phần dư",
diff --git a/frontend/src/leftoverMapExplainedShare.ts b/frontend/src/leftoverMapExplainedShare.ts
index 9f2c2215e..a1eba63cb 100644
--- a/frontend/src/leftoverMapExplainedShare.ts
+++ b/frontend/src/leftoverMapExplainedShare.ts
@@ -3,6 +3,9 @@
 export const LEFTOVER_MAP_EXPLAINED_SHARE_ACTION =
   "Leftover map leaves explained leftover share {value} of raw residual after IRT main effects. Open this post to read {criterion}.";
 
+export const LEFTOVER_MAP_COMPARE_EXPLAINED_SHARE_LABEL =
+  "Leftover map comparison explained leftover share";
+
 export function formatLeftoverMapExplainedShare(
   value: number | null | undefined,
 ): string | null {
diff --git a/lineageweave/__init__.py b/lineageweave/__init__.py
index 8bd815557..82376c516 100644
--- a/lineageweave/__init__.py
+++ b/lineageweave/__init__.py
@@ -130,4 +130,4 @@
     "serialize_lineage_analysis_result",
 ]
 
-__version__ = "2.52.0"
+__version__ = "2.53.0"
diff --git a/pyproject.toml b/pyproject.toml
index 8fc35c845..38d8858ff 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "lineageweave"
-version = "2.52.0"
+version = "2.53.0"
 description = "Reconstructs git-branch-style lineage DAGs from scattered short records using multi-channel score fusion and LLM adjudication."
 readme = "README.md"
 license = { text = "MIT" }
diff --git a/tests/test_adr_0296_governance.py b/tests/test_adr_0296_governance.py
new file mode 100644
index 000000000..8e22bf9b5
--- /dev/null
+++ b/tests/test_adr_0296_governance.py
@@ -0,0 +1,8 @@
+from pathlib import Path
+ROOT=Path(__file__).resolve().parents[1]
+def test_explained_share_comparison_uses_distinct_proposed_adr_0296() -> None:
+    assert (ROOT/'docs/adr/0295-leftover-map-compare-reconstruction.md').exists()
+    text=(ROOT/'docs/adr/0296-leftover-map-compare-explained-share.md').read_text(encoding='utf-8')
+    assert '**Decision status:** Proposed' in text
+    assert '**Decision status:** Accepted' not in text
+    assert 'accessible name' in text and 'fast-mlsirm' in text