diff --git a/src/renderer/utils/teamMessageFiltering.ts b/src/renderer/utils/teamMessageFiltering.ts
index 73f17a41..2e7c2354 100644
--- a/src/renderer/utils/teamMessageFiltering.ts
+++ b/src/renderer/utils/teamMessageFiltering.ts
@@ -19,6 +19,30 @@ export interface TeamMessagesFilter {
   showNoise: boolean;
 }
 
+interface CachedMessageFilterData {
+  readonly messageKind: InboxMessage['messageKind'];
+  readonly source: InboxMessage['source'];
+  readonly from: InboxMessage['from'];
+  readonly to: InboxMessage['to'];
+  readonly messageId: InboxMessage['messageId'];
+  readonly text: InboxMessage['text'];
+  readonly trimmedMessageId: string;
+  readonly trimmedFrom: string;
+  readonly trimmedTo: string;
+  readonly normalizedFrom: string;
+  readonly normalizedTo: string;
+  readonly normalizedText: string;
+  readonly isTaskCommentNotification: boolean;
+  readonly isTaskStallRemediation: boolean;
+  readonly isMemberWorkSyncNudge: boolean;
+  readonly isReviewPickupEscalation: boolean;
+  readonly isInternalControlEnvelope: boolean;
+  readonly isNoiseMessage: boolean;
+  readonly keepIdleWhenNoiseHidden: boolean;
+}
+
+const messageFilterDataCache = new WeakMap<InboxMessage, CachedMessageFilterData>();
+
 function normalizeMessageText(value: string | undefined): string {
   return (value ?? '')
     .trim()
@@ -41,6 +65,47 @@ function normalizeLeadNames(values: Iterable<string> | undefined): Set<string> {
   return normalized;
 }
 
+function getMessageFilterData(message: InboxMessage): CachedMessageFilterData {
+  const cached = messageFilterDataCache.get(message);
+  if (
+    cached &&
+    cached.messageKind === message.messageKind &&
+    cached.source === message.source &&
+    cached.from === message.from &&
+    cached.to === message.to &&
+    cached.messageId === message.messageId &&
+    cached.text === message.text
+  ) {
+    return cached;
+  }
+
+  const text = typeof message.text === 'string' ? message.text : '';
+  const isNoiseMessage = isInboxNoiseMessage(text);
+  const next: CachedMessageFilterData = {
+    messageKind: message.messageKind,
+    source: message.source,
+    from: message.from,
+    to: message.to,
+    messageId: message.messageId,
+    text: message.text,
+    trimmedMessageId: typeof message.messageId === 'string' ? message.messageId.trim() : '',
+    trimmedFrom: typeof message.from === 'string' ? message.from.trim() : '',
+    trimmedTo: typeof message.to === 'string' ? message.to.trim() : '',
+    normalizedFrom: normalizeParticipant(message.from),
+    normalizedTo: normalizeParticipant(message.to),
+    normalizedText: normalizeMessageText(message.text),
+    isTaskCommentNotification: message.messageKind === 'task_comment_notification',
+    isTaskStallRemediation: isTaskStallRemediationMessage(message),
+    isMemberWorkSyncNudge: isMemberWorkSyncNudgeMessage(message),
+    isReviewPickupEscalation: isReviewPickupEscalationMessage(message),
+    isInternalControlEnvelope: isTeamInternalControlMessageEnvelope(message),
+    isNoiseMessage,
+    keepIdleWhenNoiseHidden: isNoiseMessage && shouldKeepIdleMessageInActivityWhenNoiseHidden(text),
+  };
+  messageFilterDataCache.set(message, next);
+  return next;
+}
+
 function isLeadAlias(value: string | undefined): boolean {
   const normalized = normalizeParticipant(value).replace(/[\s_]+/g, '-');
   return (
@@ -65,25 +130,27 @@ function isRelayDuplicateOfVisibleMessage(
     return false;
   }
 
-  if (isInboxNoiseMessage(message.text)) {
+  const messageData = getMessageFilterData(message);
+  if (messageData.isNoiseMessage) {
     return true;
   }
+  const originalData = getMessageFilterData(original);
 
   const isInternalLeadRelayDelivery =
     (message.source === 'runtime_delivery' || message.source === 'lead_process') &&
     original.source === 'user_sent' &&
-    normalizeParticipant(original.from) === 'user' &&
+    originalData.normalizedFrom === 'user' &&
     isLeadParticipant(original.to, leadNames) &&
     isLeadParticipant(message.from, leadNames) &&
-    normalizeParticipant(message.to) !== 'user';
+    messageData.normalizedTo !== 'user';
 
   if (isInternalLeadRelayDelivery) {
     return true;
   }
 
   const sameDirection =
-    normalizeParticipant(message.from) === normalizeParticipant(original.from) &&
-    normalizeParticipant(message.to) === normalizeParticipant(original.to);
+    messageData.normalizedFrom === originalData.normalizedFrom &&
+    messageData.normalizedTo === originalData.normalizedTo;
 
   if (!sameDirection) {
     return false;
@@ -93,7 +160,7 @@ function isRelayDuplicateOfVisibleMessage(
     return true;
   }
 
-  return normalizeMessageText(message.text) === normalizeMessageText(original.text);
+  return messageData.normalizedText === originalData.normalizedText;
 }
 
 function getRuntimeDeliveryRelayDuplicateKey(
@@ -103,9 +170,10 @@ function getRuntimeDeliveryRelayDuplicateKey(
   if (message.source !== 'runtime_delivery') {
     return null;
   }
-  const from = normalizeParticipant(message.from);
-  const to = normalizeParticipant(message.to);
-  const text = normalizeMessageText(message.text);
+  const data = getMessageFilterData(message);
+  const from = data.normalizedFrom;
+  const to = data.normalizedTo;
+  const text = data.normalizedText;
   if (!from || !to || !text) {
     return null;
   }
@@ -135,14 +203,16 @@ export function filterTeamMessages(
   } = options;
   const leadNames = normalizeLeadNames(rawLeadNames);
 
-  let list = messages.filter(
-    (m) =>
-      m.messageKind !== 'task_comment_notification' &&
-      (includeAutomationEvents || !isTaskStallRemediationMessage(m)) &&
-      (includeMemberWorkSyncNudges || !isMemberWorkSyncNudgeMessage(m)) &&
-      !isReviewPickupEscalationMessage(m) &&
-      !isTeamInternalControlMessageEnvelope(m)
-  );
+  let list = messages.filter((m) => {
+    const data = getMessageFilterData(m);
+    return (
+      !data.isTaskCommentNotification &&
+      (includeAutomationEvents || !data.isTaskStallRemediation) &&
+      (includeMemberWorkSyncNudges || !data.isMemberWorkSyncNudge) &&
+      !data.isReviewPickupEscalation &&
+      !data.isInternalControlEnvelope
+    );
+  });
   if (timeWindow) {
     list = list.filter((m) => {
       const ts = new Date(m.timestamp).getTime();
@@ -151,12 +221,9 @@ export function filterTeamMessages(
   }
   if (!filter.showNoise) {
     list = list.filter((m) => {
-      const text = typeof m.text === 'string' ? m.text : '';
-      if (!isInboxNoiseMessage(text)) return true;
-      return (
-        includePassiveIdlePeerSummariesWhenNoiseHidden &&
-        shouldKeepIdleMessageInActivityWhenNoiseHidden(text)
-      );
+      const data = getMessageFilterData(m);
+      if (!data.isNoiseMessage) return true;
+      return includePassiveIdlePeerSummariesWhenNoiseHidden && data.keepIdleWhenNoiseHidden;
     });
   }
 
@@ -164,14 +231,16 @@ export function filterTeamMessages(
   const hasTo = filter.to.size > 0;
   if (hasFrom && hasTo) {
     list = list.filter((m) => {
-      const fromMatch = Boolean(m.from?.trim() && filter.from.has(m.from.trim()));
-      const toMatch = Boolean(m.to?.trim() && filter.to.has(m.to.trim()));
+      const data = getMessageFilterData(m);
+      const fromMatch = Boolean(data.trimmedFrom && filter.from.has(data.trimmedFrom));
+      const toMatch = Boolean(data.trimmedTo && filter.to.has(data.trimmedTo));
       return fromMatch && toMatch;
     });
   } else if (hasFrom || hasTo) {
     list = list.filter((m) => {
-      if (hasFrom) return Boolean(m.from?.trim() && filter.from.has(m.from.trim()));
-      if (hasTo) return Boolean(m.to?.trim() && filter.to.has(m.to.trim()));
+      const data = getMessageFilterData(m);
+      if (hasFrom) return Boolean(data.trimmedFrom && filter.from.has(data.trimmedFrom));
+      if (hasTo) return Boolean(data.trimmedTo && filter.to.has(data.trimmedTo));
       return true;
     });
   }
@@ -190,7 +259,7 @@ export function filterTeamMessages(
   const visibleMessagesById = new Map(
     list
       .map((m) => {
-        const id = typeof m.messageId === 'string' ? m.messageId.trim() : '';
+        const id = getMessageFilterData(m).trimmedMessageId;
         return id ? ([id, m] as const) : null;
       })
       .filter((entry): entry is readonly [string, InboxMessage] => entry !== null)
@@ -204,8 +273,8 @@ export function filterTeamMessages(
     if (!relayOfMessageId) {
       return true;
     }
-    const ownMessageId = typeof m.messageId === 'string' ? m.messageId.trim() : '';
-    if (relayOfMessageId === ownMessageId) {
+    const data = getMessageFilterData(m);
+    if (relayOfMessageId === data.trimmedMessageId) {
       return true;
     }
     const runtimeDuplicateKey = getRuntimeDeliveryRelayDuplicateKey(m, relayOfMessageId);
diff --git a/test/renderer/utils/teamMessageFiltering.test.ts b/test/renderer/utils/teamMessageFiltering.test.ts
index a3aad132..26314aa7 100644
--- a/test/renderer/utils/teamMessageFiltering.test.ts
+++ b/test/renderer/utils/teamMessageFiltering.test.ts
@@ -1,6 +1,5 @@
-import { describe, expect, it } from 'vitest';
-
 import { filterTeamMessages } from '@renderer/utils/teamMessageFiltering';
+import { describe, expect, it } from 'vitest';
 
 import type { InboxMessage } from '@shared/types';
 
@@ -500,6 +499,26 @@ Messages:
     expect(result[0].messageId).toBe('msg-2');
   });
 
+  it('recomputes cached message classification when mutable message fields change', () => {
+    const message = makeMessage({
+      messageId: 'mutable-message',
+      text: '{"type":"idle_notification","idleReason":"available"}',
+    });
+    const options = {
+      timeWindow: null,
+      filter: { from: new Set<string>(), to: new Set<string>(), showNoise: false },
+      searchQuery: '',
+    };
+
+    expect(filterTeamMessages([message], options)).toEqual([]);
+
+    message.text = 'Real visible message';
+
+    expect(filterTeamMessages([message], options).map((item) => item.messageId)).toEqual([
+      'mutable-message',
+    ]);
+  });
+
   it('can preserve passive peer-summary idle rows in the activity sink while keeping pure heartbeat hidden even after read', () => {
     const messages = [
       makeMessage({