diff --git a/apps/web/src/hooks/timelineSsePolicy.test.ts b/apps/web/src/hooks/timelineSsePolicy.test.ts
new file mode 100644
index 0000000..8018de7
--- /dev/null
+++ b/apps/web/src/hooks/timelineSsePolicy.test.ts
@@ -0,0 +1,36 @@
+import { SSE_EVENT_TYPES } from "@capakraken/shared";
+import { describe, expect, it } from "vitest";
+import { getTimelineSseInvalidationKeys, parseTimelineSseEvent } from "./timelineSsePolicy.js";
+
+describe("timelineSsePolicy", () => {
+  it("returns null for malformed event payloads", () => {
+    expect(parseTimelineSseEvent("{not-json")).toBeNull();
+    expect(parseTimelineSseEvent(JSON.stringify({ nope: "missing-type" }))).toBeNull();
+    expect(parseTimelineSseEvent(JSON.stringify({ type: 42 }))).toBeNull();
+  });
+
+  it("does not invalidate queries for unknown event types", () => {
+    expect(getTimelineSseInvalidationKeys("timeline.unknown")).toEqual([]);
+  });
+
+  it("maps allocation and vacation updates to planning query invalidations", () => {
+    expect(getTimelineSseInvalidationKeys(SSE_EVENT_TYPES.ALLOCATION_UPDATED)).toEqual([
+      [["timeline", "getEntries"]],
+      [["timeline", "getEntriesView"]],
+      [["timeline", "getMyEntriesView"]],
+      [["timeline", "getHolidayOverlays"]],
+      [["timeline", "getMyHolidayOverlays"]],
+      [["vacation", "list"]],
+      [["allocation", "list"]],
+    ]);
+  });
+
+  it("maps task updates to task and notification invalidations", () => {
+    expect(getTimelineSseInvalidationKeys(SSE_EVENT_TYPES.TASK_STATUS_CHANGED)).toEqual([
+      [["notification", "listTasks"]],
+      [["notification", "taskCounts"]],
+      [["notification", "list"]],
+      [["notification", "unreadCount"]],
+    ]);
+  });
+});
diff --git a/apps/web/src/hooks/timelineSsePolicy.ts b/apps/web/src/hooks/timelineSsePolicy.ts
new file mode 100644
index 0000000..90515cc
--- /dev/null
+++ b/apps/web/src/hooks/timelineSsePolicy.ts
@@ -0,0 +1,71 @@
+import { SSE_EVENT_TYPES } from "@capakraken/shared";
+
+export type TimelineQueryKey = readonly [readonly [string, string]];
+
+const TIMELINE_ENTRY_KEYS: TimelineQueryKey[] = [
+  [["timeline", "getEntries"]],
+  [["timeline", "getEntriesView"]],
+  [["timeline", "getMyEntriesView"]],
+  [["timeline", "getHolidayOverlays"]],
+  [["timeline", "getMyHolidayOverlays"]],
+];
+
+const NOTIFICATION_KEYS: TimelineQueryKey[] = [
+  [["notification", "list"]],
+  [["notification", "unreadCount"]],
+];
+
+export function parseTimelineSseEvent(rawData: string): string | null {
+  try {
+    const data = JSON.parse(rawData) as { type?: unknown };
+    return typeof data.type === "string" ? data.type : null;
+  } catch {
+    return null;
+  }
+}
+
+export function getTimelineSseInvalidationKeys(eventType: string): TimelineQueryKey[] {
+  switch (eventType) {
+    case SSE_EVENT_TYPES.ALLOCATION_CREATED:
+    case SSE_EVENT_TYPES.ALLOCATION_UPDATED:
+    case SSE_EVENT_TYPES.ALLOCATION_DELETED:
+    case SSE_EVENT_TYPES.VACATION_CREATED:
+    case SSE_EVENT_TYPES.VACATION_UPDATED:
+    case SSE_EVENT_TYPES.VACATION_DELETED:
+      return [
+        ...TIMELINE_ENTRY_KEYS,
+        [["vacation", "list"]],
+        [["allocation", "list"]],
+      ];
+
+    case SSE_EVENT_TYPES.PROJECT_SHIFTED:
+      return [
+        ...TIMELINE_ENTRY_KEYS,
+        [["project", "list"]],
+      ];
+
+    case SSE_EVENT_TYPES.BUDGET_WARNING:
+      return [[["timeline", "getBudgetStatus"]]];
+
+    case SSE_EVENT_TYPES.NOTIFICATION_CREATED:
+      return NOTIFICATION_KEYS;
+
+    case SSE_EVENT_TYPES.TASK_ASSIGNED:
+    case SSE_EVENT_TYPES.TASK_COMPLETED:
+    case SSE_EVENT_TYPES.TASK_STATUS_CHANGED:
+      return [
+        [["notification", "listTasks"]],
+        [["notification", "taskCounts"]],
+        ...NOTIFICATION_KEYS,
+      ];
+
+    case SSE_EVENT_TYPES.REMINDER_DUE:
+      return [
+        ...NOTIFICATION_KEYS,
+        [["notification", "listReminders"]],
+      ];
+
+    default:
+      return [];
+  }
+}
diff --git a/apps/web/src/hooks/useTimelineSSE.ts b/apps/web/src/hooks/useTimelineSSE.ts
index ad0a785..a875ea5 100644
--- a/apps/web/src/hooks/useTimelineSSE.ts
+++ b/apps/web/src/hooks/useTimelineSSE.ts
@@ -3,6 +3,7 @@
 import { SSE_EVENT_TYPES } from "@capakraken/shared";
 import { useQueryClient } from "@tanstack/react-query";
 import { useEffect, useRef } from "react";
+import { getTimelineSseInvalidationKeys, parseTimelineSseEvent } from "./timelineSsePolicy.js";
 
 /**
  * Connects to the SSE timeline endpoint and invalidates React Query caches
@@ -37,64 +38,18 @@ export function useTimelineSSE() {
       };
 
       es.onmessage = (event) => {
-        try {
-          const data = JSON.parse(event.data as string) as { type: string };
+        const eventType = parseTimelineSseEvent(String(event.data));
+        if (!eventType) {
+          return;
+        }
 
-          switch (data.type) {
-            case SSE_EVENT_TYPES.ALLOCATION_CREATED:
-            case SSE_EVENT_TYPES.ALLOCATION_UPDATED:
-            case SSE_EVENT_TYPES.ALLOCATION_DELETED:
-            case SSE_EVENT_TYPES.VACATION_CREATED:
-            case SSE_EVENT_TYPES.VACATION_UPDATED:
-            case SSE_EVENT_TYPES.VACATION_DELETED:
-              void queryClient.invalidateQueries({ queryKey: [["timeline", "getEntries"]] });
-              void queryClient.invalidateQueries({ queryKey: [["timeline", "getEntriesView"]] });
-              void queryClient.invalidateQueries({ queryKey: [["timeline", "getMyEntriesView"]] });
-              void queryClient.invalidateQueries({ queryKey: [["timeline", "getHolidayOverlays"]] });
-              void queryClient.invalidateQueries({ queryKey: [["timeline", "getMyHolidayOverlays"]] });
-              void queryClient.invalidateQueries({ queryKey: [["vacation", "list"]] });
-              void queryClient.invalidateQueries({ queryKey: [["allocation", "list"]] });
-              break;
+        if (eventType === SSE_EVENT_TYPES.PING) {
+          reconnectAttempts = 0;
+          return;
+        }
 
-            case SSE_EVENT_TYPES.PROJECT_SHIFTED:
-              void queryClient.invalidateQueries({ queryKey: [["timeline", "getEntries"]] });
-              void queryClient.invalidateQueries({ queryKey: [["timeline", "getEntriesView"]] });
-              void queryClient.invalidateQueries({ queryKey: [["timeline", "getMyEntriesView"]] });
-              void queryClient.invalidateQueries({ queryKey: [["timeline", "getHolidayOverlays"]] });
-              void queryClient.invalidateQueries({ queryKey: [["timeline", "getMyHolidayOverlays"]] });
-              void queryClient.invalidateQueries({ queryKey: [["project", "list"]] });
-              break;
-
-            case SSE_EVENT_TYPES.BUDGET_WARNING:
-              void queryClient.invalidateQueries({ queryKey: [["timeline", "getBudgetStatus"]] });
-              break;
-
-            case SSE_EVENT_TYPES.NOTIFICATION_CREATED:
-              void queryClient.invalidateQueries({ queryKey: [["notification", "list"]] });
-              void queryClient.invalidateQueries({ queryKey: [["notification", "unreadCount"]] });
-              break;
-
-            case SSE_EVENT_TYPES.TASK_ASSIGNED:
-            case SSE_EVENT_TYPES.TASK_COMPLETED:
-            case SSE_EVENT_TYPES.TASK_STATUS_CHANGED:
-              void queryClient.invalidateQueries({ queryKey: [["notification", "listTasks"]] });
-              void queryClient.invalidateQueries({ queryKey: [["notification", "taskCounts"]] });
-              void queryClient.invalidateQueries({ queryKey: [["notification", "unreadCount"]] });
-              void queryClient.invalidateQueries({ queryKey: [["notification", "list"]] });
-              break;
-
-            case SSE_EVENT_TYPES.REMINDER_DUE:
-              void queryClient.invalidateQueries({ queryKey: [["notification", "list"]] });
-              void queryClient.invalidateQueries({ queryKey: [["notification", "unreadCount"]] });
-              void queryClient.invalidateQueries({ queryKey: [["notification", "listReminders"]] });
-              break;
-
-            case SSE_EVENT_TYPES.PING:
-              reconnectAttempts = 0; // Reset on successful ping
-              break;
-          }
-        } catch {
-          // Ignore parse errors
+        for (const queryKey of getTimelineSseInvalidationKeys(eventType)) {
+          void queryClient.invalidateQueries({ queryKey });
         }
       };