diff --git a/apps/web/lib/xiaobao-risk-ai.test.ts b/apps/web/lib/xiaobao-risk-ai.test.ts
index 7fd18c9..7058054 100644
--- a/apps/web/lib/xiaobao-risk-ai.test.ts
+++ b/apps/web/lib/xiaobao-risk-ai.test.ts
@@ -7,6 +7,7 @@ import {
   buildRiskInterpretRequest,
   findLatestRiskInsightForVersion,
   findPreviousRiskSnapshot,
+  getReusableInsight,
   shouldRequestRiskInsight,
   shouldRequestRiskInsightWithCacheGate,
   shouldRequestRiskInsightWithCooldown,
@@ -328,6 +329,38 @@ test('buildRiskInsightSignature changes when trend direction delta or activity m
   assert.notEqual(base, changed);
 });
 
+test('buildRiskInsightSignature stays stable when only volatile same-day forecast timing changes', () => {
+  const base = buildRiskInsightSignature(risk({
+    forecastReleaseDate: '2026-07-14T03:06:58.211Z',
+    signals: { ...risk().signals, daysToExpectedRelease: 30.9 },
+  }));
+  const changed = buildRiskInsightSignature(risk({
+    forecastReleaseDate: '2026-07-14T03:37:15.903Z',
+    signals: { ...risk().signals, daysToExpectedRelease: 30.1 },
+  }));
+
+  assert.equal(base, changed);
+});
+
+test('getReusableInsight reuses legacy signatures with volatile forecast timestamps', () => {
+  const current = risk({
+    forecastReleaseDate: '2026-07-14T03:37:15.903Z',
+    signals: { ...risk().signals, daysToExpectedRelease: 30.1 },
+  });
+  const legacy = insight({
+    riskSignature: JSON.stringify({
+      ...JSON.parse(buildRiskInsightSignature(current)),
+      forecastReleaseDate: '2026-07-14T03:06:58.211Z',
+      signals: {
+        ...current.signals,
+        daysToExpectedRelease: 30.9,
+      },
+    }),
+  });
+
+  assert.equal(getReusableInsight([legacy], current)?.insight.summary, legacy.insight.summary);
+});
+
 test('buildRiskInterpretRequest compresses frontend risk evidence for the backend AI contract', () => {
   const payload = buildRiskInterpretRequest(risk());
 
diff --git a/apps/web/lib/xiaobao-risk-ai.ts b/apps/web/lib/xiaobao-risk-ai.ts
index 7219dfe..b9123f8 100644
--- a/apps/web/lib/xiaobao-risk-ai.ts
+++ b/apps/web/lib/xiaobao-risk-ai.ts
@@ -108,8 +108,8 @@ export function buildRiskInsightSignature(risk: XiaobaoVersionRisk): string {
     versionId: risk.versionId,
     riskScore: clampScore(risk.riskScore),
     riskLevel: risk.riskLevel,
-    expectedReleaseDate: risk.expectedReleaseDate ?? null,
-    forecastReleaseDate: risk.forecastReleaseDate ?? null,
+    expectedReleaseDate: normalizeDateKey(risk.expectedReleaseDate),
+    forecastReleaseDate: normalizeDateKey(risk.forecastReleaseDate),
     delayDays: risk.delayDays,
     confidence: clampScore(risk.confidence),
     signals: {
@@ -119,7 +119,7 @@ export function buildRiskInsightSignature(risk: XiaobaoVersionRisk): string {
       failedTestCount: risk.signals.failedTestCount,
       blockedCount: risk.signals.blockedCount,
       silentRiskCount: risk.signals.silentRiskCount,
-      daysToExpectedRelease: risk.signals.daysToExpectedRelease ?? null,
+      daysToExpectedRelease: normalizeDaysToExpectedRelease(risk.signals.daysToExpectedRelease),
     },
     trend: {
       direction: risk.trend.direction,
@@ -145,7 +145,11 @@ export function getReusableInsight(
   cache: XiaobaoRiskInsightCacheItem[],
   risk: XiaobaoVersionRisk,
 ): XiaobaoRiskInsightCacheItem | undefined {
-  return findCachedInsight(cache, risk.versionId, buildRiskInsightSignature(risk));
+  const currentSignature = buildRiskInsightSignature(risk);
+  return (
+    findCachedInsight(cache, risk.versionId, currentSignature) ??
+    cache.find((item) => item.versionId === risk.versionId && normalizeCachedRiskSignature(item.riskSignature) === currentSignature)
+  );
 }
 
 export function findPreviousRiskSnapshot(
@@ -284,6 +288,43 @@ function parseRiskLevel(signature: string): XiaobaoVersionRisk['riskLevel'] | un
   }
 }
 
+function normalizeCachedRiskSignature(signature: string): string | undefined {
+  try {
+    const parsed = JSON.parse(signature) as {
+      expectedReleaseDate?: string | null;
+      forecastReleaseDate?: string | null;
+      signals?: { daysToExpectedRelease?: number | null };
+    };
+    return JSON.stringify({
+      ...parsed,
+      expectedReleaseDate: normalizeDateKey(parsed.expectedReleaseDate),
+      forecastReleaseDate: normalizeDateKey(parsed.forecastReleaseDate),
+      signals: {
+        ...parsed.signals,
+        daysToExpectedRelease: normalizeDaysToExpectedRelease(parsed.signals?.daysToExpectedRelease),
+      },
+    });
+  } catch {
+    return undefined;
+  }
+}
+
+function normalizeDateKey(value: string | null | undefined): string | null {
+  if (!value) return null;
+  const raw = value.trim();
+  if (raw.length === 0) return null;
+  if (/^\d{4}-\d{2}-\d{2}/.test(raw)) return raw.slice(0, 10);
+
+  const time = new Date(raw).getTime();
+  if (!Number.isFinite(time)) return raw;
+  return new Date(time).toISOString().slice(0, 10);
+}
+
+function normalizeDaysToExpectedRelease(value: number | null | undefined): number | null {
+  if (value === null || value === undefined || !Number.isFinite(value)) return null;
+  return value >= 0 ? Math.ceil(value) : Math.floor(value);
+}
+
 function getTime(value: string): number {
   const time = new Date(value).getTime();
   return Number.isFinite(time) ? time : Number.NaN;