From cc38cb121f2c061abfae9ff18b64efb5bfb0776b Mon Sep 17 00:00:00 2001
From: Assem Hafez <assem.hafez@uber.com>
Date: Thu, 20 Nov 2025 01:34:56 +0000
Subject: [PATCH 01/13] fetcher updates

---
 .../workflow-history-v2.tsx                   |  2 +-
 .../workflow-history-page-size.config.ts      |  5 +-
 .../workflow-history-fetcher.test.tsx         | 49 +++++++++++++++++--
 .../helpers/workflow-history-fetcher.ts       |  9 +++-
 .../use-workflow-history-fetcher.test.tsx     |  6 ++-
 .../hooks/use-workflow-history-fetcher.ts     | 15 ++++--
 .../workflow-history/workflow-history.tsx     |  2 +-
 7 files changed, 74 insertions(+), 14 deletions(-)

diff --git a/src/views/workflow-history-v2/workflow-history-v2.tsx b/src/views/workflow-history-v2/workflow-history-v2.tsx
index 6f33a88db..fcdd0358b 100644
--- a/src/views/workflow-history-v2/workflow-history-v2.tsx
+++ b/src/views/workflow-history-v2/workflow-history-v2.tsx
@@ -4,7 +4,7 @@ import usePageFilters from '@/components/page-filters/hooks/use-page-filters';
 import decodeUrlParams from '@/utils/decode-url-params';
 
 import workflowHistoryFiltersConfig from '../workflow-history/config/workflow-history-filters.config';
-import WORKFLOW_HISTORY_PAGE_SIZE_CONFIG from '../workflow-history/config/workflow-history-page-size.config';
+import { WORKFLOW_HISTORY_PAGE_SIZE_CONFIG } from '../workflow-history/config/workflow-history-page-size.config';
 import { WorkflowHistoryContext } from '../workflow-history/workflow-history-context-provider/workflow-history-context-provider';
 import workflowPageQueryParamsConfig from '../workflow-page/config/workflow-page-query-params.config';
 import { type WorkflowPageTabContentParams } from '../workflow-page/workflow-page-tab-content/workflow-page-tab-content.types';
diff --git a/src/views/workflow-history/config/workflow-history-page-size.config.ts b/src/views/workflow-history/config/workflow-history-page-size.config.ts
index 933cf92dd..453efac10 100644
--- a/src/views/workflow-history/config/workflow-history-page-size.config.ts
+++ b/src/views/workflow-history/config/workflow-history-page-size.config.ts
@@ -1,3 +1,2 @@
-const WORKFLOW_HISTORY_PAGE_SIZE_CONFIG = 200;
-
-export default WORKFLOW_HISTORY_PAGE_SIZE_CONFIG;
+export const WORKFLOW_HISTORY_PAGE_SIZE_CONFIG = 1000;
+export const WORKFLOW_HISTORY_FIRST_PAGE_SIZE_CONFIG = 200;
diff --git a/src/views/workflow-history/helpers/__tests__/workflow-history-fetcher.test.tsx b/src/views/workflow-history/helpers/__tests__/workflow-history-fetcher.test.tsx
index f2d59e315..23ab86ed2 100644
--- a/src/views/workflow-history/helpers/__tests__/workflow-history-fetcher.test.tsx
+++ b/src/views/workflow-history/helpers/__tests__/workflow-history-fetcher.test.tsx
@@ -262,6 +262,37 @@ describe(WorkflowHistoryFetcher.name, () => {
     const state = fetcher.getCurrentState();
     expect(state.data?.pages.length).toBe(pageCountBefore);
   });
+
+  it('should use WORKFLOW_HISTORY_FIRST_PAGE_SIZE_CONFIG for the first page', async () => {
+    const { fetcher, getCapturedPageSizes } = setup(queryClient);
+
+    fetcher.start((state) => !state?.data?.pages?.length);
+
+    await waitFor(() => {
+      const state = fetcher.getCurrentState();
+      expect(state.data?.pages).toHaveLength(1);
+    });
+
+    const pageSizes = getCapturedPageSizes();
+    expect(pageSizes).toHaveLength(1);
+    expect(pageSizes[0]).toBe('200');
+  });
+
+  it('should use WORKFLOW_HISTORY_PAGE_SIZE_CONFIG for subsequent pages', async () => {
+    const { fetcher, getCapturedPageSizes } = setup(queryClient);
+
+    fetcher.start((state) => (state.data?.pages.length || 0) < 2);
+
+    await waitFor(() => {
+      const state = fetcher.getCurrentState();
+      expect(state.data?.pages).toHaveLength(2);
+    });
+
+    const pageSizes = getCapturedPageSizes();
+    expect(pageSizes.length).toBeGreaterThanOrEqual(2);
+    expect(pageSizes[0]).toBe('200');
+    expect(pageSizes[1]).toBe('1000');
+  });
 });
 
 function setup(client: QueryClient, options: { failOnPages?: number[] } = {}) {
@@ -273,7 +304,10 @@ function setup(client: QueryClient, options: { failOnPages?: number[] } = {}) {
     pageSize: 10,
   };
 
-  mockHistoryEndpoint(workflowHistoryMultiPageFixture, options.failOnPages);
+  const { getCapturedPageSizes } = mockHistoryEndpoint(
+    workflowHistoryMultiPageFixture,
+    options.failOnPages
+  );
   const fetcher = new WorkflowHistoryFetcher(client, params);
   hoistedFetcher = fetcher;
 
@@ -292,6 +326,7 @@ function setup(client: QueryClient, options: { failOnPages?: number[] } = {}) {
     fetcher,
     params,
     waitForData,
+    getCapturedPageSizes,
   };
 }
 
@@ -299,6 +334,8 @@ function mockHistoryEndpoint(
   responses: GetWorkflowHistoryResponse[],
   failOnPages: number[] = []
 ) {
+  const capturedPageSizes: string[] = [];
+
   mswMockEndpoints([
     {
       path: '/api/domains/:domain/:cluster/workflows/:workflowId/:runId/history',
@@ -307,6 +344,9 @@ function mockHistoryEndpoint(
       httpResolver: async ({ request }) => {
         const url = new URL(request.url);
         const nextPage = url.searchParams.get('nextPage');
+        const pageSize = url.searchParams.get('pageSize');
+
+        capturedPageSizes.push(pageSize ?? '');
 
         // Determine current page number based on nextPage param
         let pageNumber = 1;
@@ -328,10 +368,13 @@ function mockHistoryEndpoint(
 
         // Map page number to response index (0-indexed)
         const responseIndex = pageNumber - 1;
-        const response =
-          responses[responseIndex] || responses[responses.length - 1];
+        const response = responses[responseIndex];
         return HttpResponse.json(response);
       },
     },
   ]);
+
+  return {
+    getCapturedPageSizes: () => capturedPageSizes,
+  };
 }
diff --git a/src/views/workflow-history/helpers/workflow-history-fetcher.ts b/src/views/workflow-history/helpers/workflow-history-fetcher.ts
index a43dfaa31..718b21093 100644
--- a/src/views/workflow-history/helpers/workflow-history-fetcher.ts
+++ b/src/views/workflow-history/helpers/workflow-history-fetcher.ts
@@ -7,6 +7,11 @@ import {
 } from '@/route-handlers/get-workflow-history/get-workflow-history.types';
 import request from '@/utils/request';
 
+import {
+  WORKFLOW_HISTORY_FIRST_PAGE_SIZE_CONFIG,
+  WORKFLOW_HISTORY_PAGE_SIZE_CONFIG,
+} from '../config/workflow-history-page-size.config';
+
 import {
   type WorkflowHistoryQueryResult,
   type QueryResultOnChangeCallback,
@@ -126,7 +131,9 @@ export default class WorkflowHistoryFetcher {
             url: `/api/domains/${params.domain}/${params.cluster}/workflows/${params.workflowId}/${params.runId}/history`,
             query: {
               nextPage: pageParam,
-              pageSize: params.pageSize,
+              pageSize: pageParam
+                ? WORKFLOW_HISTORY_PAGE_SIZE_CONFIG
+                : WORKFLOW_HISTORY_FIRST_PAGE_SIZE_CONFIG,
               waitForNewEvent: params.waitForNewEvent ?? false,
             } satisfies WorkflowHistoryQueryParams,
           })
diff --git a/src/views/workflow-history/hooks/__tests__/use-workflow-history-fetcher.test.tsx b/src/views/workflow-history/hooks/__tests__/use-workflow-history-fetcher.test.tsx
index 8f67dcbb7..0cb9e7332 100644
--- a/src/views/workflow-history/hooks/__tests__/use-workflow-history-fetcher.test.tsx
+++ b/src/views/workflow-history/hooks/__tests__/use-workflow-history-fetcher.test.tsx
@@ -19,13 +19,17 @@ let mockOnChangeCallback: jest.Mock;
 let mockUnsubscribe: jest.Mock;
 
 function setup() {
-  const hookResult = renderHook(() => useWorkflowHistoryFetcher(mockParams));
+  const mockOnEventsChange = jest.fn();
+  const hookResult = renderHook(() =>
+    useWorkflowHistoryFetcher(mockParams, mockOnEventsChange)
+  );
 
   return {
     ...hookResult,
     mockFetcherInstance,
     mockOnChangeCallback,
     mockUnsubscribe,
+    mockOnEventsChange,
   };
 }
 
diff --git a/src/views/workflow-history/hooks/use-workflow-history-fetcher.ts b/src/views/workflow-history/hooks/use-workflow-history-fetcher.ts
index c287edfd3..3609e3bbf 100644
--- a/src/views/workflow-history/hooks/use-workflow-history-fetcher.ts
+++ b/src/views/workflow-history/hooks/use-workflow-history-fetcher.ts
@@ -6,6 +6,7 @@ import {
   useQueryClient,
 } from '@tanstack/react-query';
 
+import { type HistoryEvent } from '@/__generated__/proto-ts/uber/cadence/api/v1/HistoryEvent';
 import useThrottledState from '@/hooks/use-throttled-state';
 import {
   type WorkflowHistoryQueryParams,
@@ -19,6 +20,7 @@ import { type ShouldContinueCallback } from '../helpers/workflow-history-fetcher
 
 export default function useWorkflowHistoryFetcher(
   params: WorkflowHistoryQueryParams & RouteParams,
+  onEventsChange: (events: HistoryEvent[]) => void,
   throttleMs: number = 2000
 ) {
   const queryClient = useQueryClient();
@@ -26,6 +28,9 @@ export default function useWorkflowHistoryFetcher(
 
   if (!fetcherRef.current) {
     fetcherRef.current = new WorkflowHistoryFetcher(queryClient, params);
+
+    // Fetch first page
+    fetcherRef.current.start((state) => !state?.data?.pages?.length);
   }
 
   const [historyQuery, setHistoryQuery] = useThrottledState<
@@ -43,20 +48,22 @@ export default function useWorkflowHistoryFetcher(
 
     const unsubscribe = fetcherRef.current.onChange((state) => {
       const pagesCount = state.data?.pages?.length || 0;
+      onEventsChange(
+        state.data?.pages?.flatMap((page) => page.history?.events || []) || []
+      );
       // immediately set if there is the first page without throttling other wise throttle
       const executeImmediately = pagesCount <= 1;
       setHistoryQuery(() => state, executeImmediately);
     });
 
-    // Fetch first page
-    fetcherRef.current.start((state) => !state?.data?.pages?.length);
-
     return () => {
       unsubscribe();
     };
-  }, [setHistoryQuery]);
+  }, [setHistoryQuery, onEventsChange]);
 
   useEffect(() => {
+    if (!fetcherRef.current) return;
+
     return () => {
       fetcherRef.current?.destroy();
     };
diff --git a/src/views/workflow-history/workflow-history.tsx b/src/views/workflow-history/workflow-history.tsx
index ef69c835b..7b8b5a81a 100644
--- a/src/views/workflow-history/workflow-history.tsx
+++ b/src/views/workflow-history/workflow-history.tsx
@@ -25,7 +25,7 @@ import workflowPageQueryParamsConfig from '../workflow-page/config/workflow-page
 import { useSuspenseDescribeWorkflow } from '../workflow-page/hooks/use-describe-workflow';
 
 import workflowHistoryFiltersConfig from './config/workflow-history-filters.config';
-import WORKFLOW_HISTORY_PAGE_SIZE_CONFIG from './config/workflow-history-page-size.config';
+import { WORKFLOW_HISTORY_PAGE_SIZE_CONFIG } from './config/workflow-history-page-size.config';
 import compareUngroupedEvents from './helpers/compare-ungrouped-events';
 import getSortableEventId from './helpers/get-sortable-event-id';
 import getVisibleGroupsHasMissingEvents from './helpers/get-visible-groups-has-missing-events';

From 2a41fc674e3599cd78dd4dec9eccdc2a764a76f6 Mon Sep 17 00:00:00 2001
From: Assem Hafez <assem.hafez@uber.com>
Date: Thu, 20 Nov 2025 10:03:17 +0000
Subject: [PATCH 02/13] add placeholder for fetcher

---
 src/views/workflow-history/workflow-history.tsx | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/views/workflow-history/workflow-history.tsx b/src/views/workflow-history/workflow-history.tsx
index 7b8b5a81a..867711826 100644
--- a/src/views/workflow-history/workflow-history.tsx
+++ b/src/views/workflow-history/workflow-history.tsx
@@ -73,6 +73,8 @@ export default function WorkflowHistory({ params }: Props) {
       pageSize: wfHistoryRequestArgs.pageSize,
       waitForNewEvent: wfHistoryRequestArgs.waitForNewEvent,
     },
+    //TODO replace this with grouper callback
+    () => {},
     2000
   );
 

From 1f54d952d70deb519d8364c6cce7b6ba900fd858 Mon Sep 17 00:00:00 2001
From: Assem Hafez <assem.hafez@uber.com>
Date: Thu, 20 Nov 2025 10:04:43 +0000
Subject: [PATCH 03/13] update fetcher mock

---
 .../workflow-history/__tests__/workflow-history.test.tsx     | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/views/workflow-history/__tests__/workflow-history.test.tsx b/src/views/workflow-history/__tests__/workflow-history.test.tsx
index 797b1fde6..3a7a63400 100644
--- a/src/views/workflow-history/__tests__/workflow-history.test.tsx
+++ b/src/views/workflow-history/__tests__/workflow-history.test.tsx
@@ -29,11 +29,14 @@ jest.mock('@/hooks/use-page-query-params/use-page-query-params', () =>
 );
 
 // Mock the hook to use minimal throttle delay for faster tests
+// Mock the hooks to use minimal throttle delay for faster tests
 jest.mock('../hooks/use-workflow-history-fetcher', () => {
   const actual = jest.requireActual('../hooks/use-workflow-history-fetcher');
   return {
     __esModule: true,
-    default: jest.fn((params) => actual.default(params, 0)), // 0ms throttle for tests
+    default: jest.fn((params, onEventsChange) =>
+      actual.default(params, onEventsChange, 0)
+    ), // 0ms throttle for tests
   };
 });
 

From 3398d8ae83520ae861f707f5f23ab12e14c9e6bc Mon Sep 17 00:00:00 2001
From: Assem Hafez <assem.hafez@uber.com>
Date: Thu, 20 Nov 2025 10:47:07 +0000
Subject: [PATCH 04/13] fetcher start update

---
 .../helpers/workflow-history-fetcher.ts              | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/src/views/workflow-history/helpers/workflow-history-fetcher.ts b/src/views/workflow-history/helpers/workflow-history-fetcher.ts
index 718b21093..9141698b9 100644
--- a/src/views/workflow-history/helpers/workflow-history-fetcher.ts
+++ b/src/views/workflow-history/helpers/workflow-history-fetcher.ts
@@ -49,13 +49,17 @@ export default class WorkflowHistoryFetcher {
     if (shouldContinue) {
       this.shouldContinue = shouldContinue;
     }
-    // If already started, return
-    if (this.isStarted) return;
+
+    // remove current listener (if exists) to have fresh emits only
+    this.unsubscribe?.();
+    this.unsubscribe = null;
+
     this.isStarted = true;
     let emitCount = 0;
     const currentState = this.observer.getCurrentResult();
     const fetchedFirstPage = currentState.status !== 'pending';
-    const shouldEnableQuery = !fetchedFirstPage && shouldContinue(currentState);
+    const shouldEnableQuery =
+      !fetchedFirstPage && this.shouldContinue(currentState);
 
     if (shouldEnableQuery) {
       this.observer.setOptions({
@@ -86,8 +90,6 @@ export default class WorkflowHistoryFetcher {
       emit(currentState);
     }
 
-    // remove current listener (if exists) and add new one
-    this.unsubscribe?.();
     this.unsubscribe = this.observer.subscribe((res) => emit(res));
   }
 

From fb1f87ca1e5f08a1197d3a042c5fb4ea2b17592a Mon Sep 17 00:00:00 2001
From: Assem Hafez <assem.hafez@uber.com>
Date: Thu, 20 Nov 2025 10:47:43 +0000
Subject: [PATCH 05/13] update todo

---
 src/views/workflow-history/workflow-history.tsx | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/views/workflow-history/workflow-history.tsx b/src/views/workflow-history/workflow-history.tsx
index 867711826..571ed112c 100644
--- a/src/views/workflow-history/workflow-history.tsx
+++ b/src/views/workflow-history/workflow-history.tsx
@@ -73,7 +73,7 @@ export default function WorkflowHistory({ params }: Props) {
       pageSize: wfHistoryRequestArgs.pageSize,
       waitForNewEvent: wfHistoryRequestArgs.waitForNewEvent,
     },
-    //TODO replace this with grouper callback
+    //TODO: @assem.hafez replace this with grouper callback
     () => {},
     2000
   );

From 650a918bb252317f8ae963fc3f27e88a166621d2 Mon Sep 17 00:00:00 2001
From: Assem Hafez <137278762+Assem-Uber@users.noreply.github.com>
Date: Thu, 20 Nov 2025 13:45:48 +0100
Subject: [PATCH 06/13] Apply suggestion from @Copilot

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
---
 .../helpers/__tests__/workflow-history-fetcher.test.tsx         | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/views/workflow-history/helpers/__tests__/workflow-history-fetcher.test.tsx b/src/views/workflow-history/helpers/__tests__/workflow-history-fetcher.test.tsx
index 23ab86ed2..0858d0caf 100644
--- a/src/views/workflow-history/helpers/__tests__/workflow-history-fetcher.test.tsx
+++ b/src/views/workflow-history/helpers/__tests__/workflow-history-fetcher.test.tsx
@@ -368,7 +368,7 @@ function mockHistoryEndpoint(
 
         // Map page number to response index (0-indexed)
         const responseIndex = pageNumber - 1;
-        const response = responses[responseIndex];
+        const response = responses[responseIndex] || responses[responses.length - 1];
         return HttpResponse.json(response);
       },
     },

From a9e94696aa2a7d7ad47ad906b1d11cd376e6648b Mon Sep 17 00:00:00 2001
From: Assem Hafez <assem.hafez@uber.com>
Date: Thu, 20 Nov 2025 14:25:43 +0100
Subject: [PATCH 07/13] fix copilot comments

---
 .../hooks/use-workflow-history-fetcher.ts          | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/src/views/workflow-history/hooks/use-workflow-history-fetcher.ts b/src/views/workflow-history/hooks/use-workflow-history-fetcher.ts
index 3609e3bbf..ae36a866c 100644
--- a/src/views/workflow-history/hooks/use-workflow-history-fetcher.ts
+++ b/src/views/workflow-history/hooks/use-workflow-history-fetcher.ts
@@ -45,12 +45,16 @@ export default function useWorkflowHistoryFetcher(
 
   useEffect(() => {
     if (!fetcherRef.current) return;
-
+    let lastFlattenedPagesCount: number = 0;
     const unsubscribe = fetcherRef.current.onChange((state) => {
       const pagesCount = state.data?.pages?.length || 0;
-      onEventsChange(
-        state.data?.pages?.flatMap((page) => page.history?.events || []) || []
-      );
+      // if the pages count is greater than the last flattened pages count, then we need to flatten the pages and call the onEventsChange callback
+      if (pagesCount > lastFlattenedPagesCount) {
+        lastFlattenedPagesCount = pagesCount;
+        onEventsChange(
+          state.data?.pages?.flatMap((page) => page.history?.events || []) || []
+        );
+      }
       // immediately set if there is the first page without throttling other wise throttle
       const executeImmediately = pagesCount <= 1;
       setHistoryQuery(() => state, executeImmediately);
@@ -62,8 +66,6 @@ export default function useWorkflowHistoryFetcher(
   }, [setHistoryQuery, onEventsChange]);
 
   useEffect(() => {
-    if (!fetcherRef.current) return;
-
     return () => {
       fetcherRef.current?.destroy();
     };

From 8dcf01c6b145d717775b5144e183bc31b1c9adb6 Mon Sep 17 00:00:00 2001
From: Assem Hafez <assem.hafez@uber.com>
Date: Thu, 20 Nov 2025 14:27:18 +0100
Subject: [PATCH 08/13] remove extra comment

---
 src/views/workflow-history/__tests__/workflow-history.test.tsx | 1 -
 1 file changed, 1 deletion(-)

diff --git a/src/views/workflow-history/__tests__/workflow-history.test.tsx b/src/views/workflow-history/__tests__/workflow-history.test.tsx
index 3a7a63400..8109f4aad 100644
--- a/src/views/workflow-history/__tests__/workflow-history.test.tsx
+++ b/src/views/workflow-history/__tests__/workflow-history.test.tsx
@@ -29,7 +29,6 @@ jest.mock('@/hooks/use-page-query-params/use-page-query-params', () =>
 );
 
 // Mock the hook to use minimal throttle delay for faster tests
-// Mock the hooks to use minimal throttle delay for faster tests
 jest.mock('../hooks/use-workflow-history-fetcher', () => {
   const actual = jest.requireActual('../hooks/use-workflow-history-fetcher');
   return {

From 573c1951ed218691e642b7bb04c34c2d8791df05 Mon Sep 17 00:00:00 2001
From: Assem Hafez <assem.hafez@uber.com>
Date: Thu, 20 Nov 2025 13:30:22 +0000
Subject: [PATCH 09/13] lint fix

---
 .../helpers/__tests__/workflow-history-fetcher.test.tsx        | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/views/workflow-history/helpers/__tests__/workflow-history-fetcher.test.tsx b/src/views/workflow-history/helpers/__tests__/workflow-history-fetcher.test.tsx
index 0858d0caf..7c0f89c91 100644
--- a/src/views/workflow-history/helpers/__tests__/workflow-history-fetcher.test.tsx
+++ b/src/views/workflow-history/helpers/__tests__/workflow-history-fetcher.test.tsx
@@ -368,7 +368,8 @@ function mockHistoryEndpoint(
 
         // Map page number to response index (0-indexed)
         const responseIndex = pageNumber - 1;
-        const response = responses[responseIndex] || responses[responses.length - 1];
+        const response =
+          responses[responseIndex] || responses[responses.length - 1];
         return HttpResponse.json(response);
       },
     },

From 730666333bf93d31583f8897d674e738e3602199 Mon Sep 17 00:00:00 2001
From: Assem Hafez <assem.hafez@uber.com>
Date: Thu, 20 Nov 2025 13:33:41 +0000
Subject: [PATCH 10/13] change lastFlattented initial value to -1

---
 .../workflow-history/hooks/use-workflow-history-fetcher.ts      | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/views/workflow-history/hooks/use-workflow-history-fetcher.ts b/src/views/workflow-history/hooks/use-workflow-history-fetcher.ts
index ae36a866c..6ced9b164 100644
--- a/src/views/workflow-history/hooks/use-workflow-history-fetcher.ts
+++ b/src/views/workflow-history/hooks/use-workflow-history-fetcher.ts
@@ -45,7 +45,7 @@ export default function useWorkflowHistoryFetcher(
 
   useEffect(() => {
     if (!fetcherRef.current) return;
-    let lastFlattenedPagesCount: number = 0;
+    let lastFlattenedPagesCount: number = -1;
     const unsubscribe = fetcherRef.current.onChange((state) => {
       const pagesCount = state.data?.pages?.length || 0;
       // if the pages count is greater than the last flattened pages count, then we need to flatten the pages and call the onEventsChange callback

From 73e9bd8661634745e66a552733af05849a5677ef Mon Sep 17 00:00:00 2001
From: Assem Hafez <assem.hafez@uber.com>
Date: Thu, 20 Nov 2025 22:22:38 +0000
Subject: [PATCH 11/13] move lastFlattenedPagesCount to a ref and remove
 shouldContinue condition

---
 .../workflow-history/helpers/workflow-history-fetcher.ts | 4 +---
 .../hooks/use-workflow-history-fetcher.ts                | 9 +++++----
 2 files changed, 6 insertions(+), 7 deletions(-)

diff --git a/src/views/workflow-history/helpers/workflow-history-fetcher.ts b/src/views/workflow-history/helpers/workflow-history-fetcher.ts
index 9141698b9..d05f4d63f 100644
--- a/src/views/workflow-history/helpers/workflow-history-fetcher.ts
+++ b/src/views/workflow-history/helpers/workflow-history-fetcher.ts
@@ -46,9 +46,7 @@ export default class WorkflowHistoryFetcher {
   }
 
   start(shouldContinue: ShouldContinueCallback = () => true): void {
-    if (shouldContinue) {
-      this.shouldContinue = shouldContinue;
-    }
+    this.shouldContinue = shouldContinue;
 
     // remove current listener (if exists) to have fresh emits only
     this.unsubscribe?.();
diff --git a/src/views/workflow-history/hooks/use-workflow-history-fetcher.ts b/src/views/workflow-history/hooks/use-workflow-history-fetcher.ts
index 6ced9b164..5e1cfed80 100644
--- a/src/views/workflow-history/hooks/use-workflow-history-fetcher.ts
+++ b/src/views/workflow-history/hooks/use-workflow-history-fetcher.ts
@@ -25,6 +25,7 @@ export default function useWorkflowHistoryFetcher(
 ) {
   const queryClient = useQueryClient();
   const fetcherRef = useRef<WorkflowHistoryFetcher | null>(null);
+  const lastFlattenedPagesCountRef = useRef<number>(-1);
 
   if (!fetcherRef.current) {
     fetcherRef.current = new WorkflowHistoryFetcher(queryClient, params);
@@ -45,12 +46,12 @@ export default function useWorkflowHistoryFetcher(
 
   useEffect(() => {
     if (!fetcherRef.current) return;
-    let lastFlattenedPagesCount: number = -1;
     const unsubscribe = fetcherRef.current.onChange((state) => {
       const pagesCount = state.data?.pages?.length || 0;
-      // if the pages count is greater than the last flattened pages count, then we need to flatten the pages and call the onEventsChange callback
-      if (pagesCount > lastFlattenedPagesCount) {
-        lastFlattenedPagesCount = pagesCount;
+      // If the pages count is greater than the last flattened pages count, then we need to flatten the pages and call the onEventsChange callback
+      // Depending on ref variable instead of historyQueue is because historyQueue is throttled.
+      if (pagesCount > lastFlattenedPagesCountRef.current) {
+        lastFlattenedPagesCountRef.current = pagesCount;
         onEventsChange(
           state.data?.pages?.flatMap((page) => page.history?.events || []) || []
         );

From f8e080db8dfde686ed21dcf9a3fe7df44fc76006 Mon Sep 17 00:00:00 2001
From: Assem Hafez <assem.hafez@uber.com>
Date: Fri, 21 Nov 2025 12:28:25 +0000
Subject: [PATCH 12/13] fix typo and add mock for configs

---
 .../helpers/__tests__/workflow-history-fetcher.test.tsx  | 9 +++++++++
 .../hooks/use-workflow-history-fetcher.ts                | 2 +-
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/src/views/workflow-history/helpers/__tests__/workflow-history-fetcher.test.tsx b/src/views/workflow-history/helpers/__tests__/workflow-history-fetcher.test.tsx
index 7c0f89c91..311b99574 100644
--- a/src/views/workflow-history/helpers/__tests__/workflow-history-fetcher.test.tsx
+++ b/src/views/workflow-history/helpers/__tests__/workflow-history-fetcher.test.tsx
@@ -15,6 +15,15 @@ const RETRY_COUNT = 3;
 let queryClient: QueryClient;
 let hoistedFetcher: WorkflowHistoryFetcher;
 
+jest.mock(
+  '@/views/workflow-history/config/workflow-history-page-size.config',
+  () => ({
+    __esModule: true,
+    WORKFLOW_HISTORY_FIRST_PAGE_SIZE_CONFIG: 200,
+    WORKFLOW_HISTORY_PAGE_SIZE_CONFIG: 1000,
+  })
+);
+
 describe(WorkflowHistoryFetcher.name, () => {
   beforeEach(() => {
     queryClient = new QueryClient({
diff --git a/src/views/workflow-history/hooks/use-workflow-history-fetcher.ts b/src/views/workflow-history/hooks/use-workflow-history-fetcher.ts
index 5e1cfed80..94921e7f4 100644
--- a/src/views/workflow-history/hooks/use-workflow-history-fetcher.ts
+++ b/src/views/workflow-history/hooks/use-workflow-history-fetcher.ts
@@ -49,7 +49,7 @@ export default function useWorkflowHistoryFetcher(
     const unsubscribe = fetcherRef.current.onChange((state) => {
       const pagesCount = state.data?.pages?.length || 0;
       // If the pages count is greater than the last flattened pages count, then we need to flatten the pages and call the onEventsChange callback
-      // Depending on ref variable instead of historyQueue is because historyQueue is throttled.
+      // Depending on ref variable instead of historyQuery is because historyQuery is throttled.
       if (pagesCount > lastFlattenedPagesCountRef.current) {
         lastFlattenedPagesCountRef.current = pagesCount;
         onEventsChange(

From d9da99f53712f1ef6b255c903c69043d4819232d Mon Sep 17 00:00:00 2001
From: Assem Hafez <assem.hafez@uber.com>
Date: Fri, 21 Nov 2025 12:32:42 +0000
Subject: [PATCH 13/13] update page size test case

---
 .../helpers/__tests__/workflow-history-fetcher.test.tsx   | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/src/views/workflow-history/helpers/__tests__/workflow-history-fetcher.test.tsx b/src/views/workflow-history/helpers/__tests__/workflow-history-fetcher.test.tsx
index 311b99574..f997bcc31 100644
--- a/src/views/workflow-history/helpers/__tests__/workflow-history-fetcher.test.tsx
+++ b/src/views/workflow-history/helpers/__tests__/workflow-history-fetcher.test.tsx
@@ -283,24 +283,22 @@ describe(WorkflowHistoryFetcher.name, () => {
     });
 
     const pageSizes = getCapturedPageSizes();
-    expect(pageSizes).toHaveLength(1);
     expect(pageSizes[0]).toBe('200');
   });
 
   it('should use WORKFLOW_HISTORY_PAGE_SIZE_CONFIG for subsequent pages', async () => {
     const { fetcher, getCapturedPageSizes } = setup(queryClient);
 
-    fetcher.start((state) => (state.data?.pages.length || 0) < 2);
+    fetcher.start((state) => (state.data?.pages.length || 0) < 3);
 
     await waitFor(() => {
       const state = fetcher.getCurrentState();
-      expect(state.data?.pages).toHaveLength(2);
+      expect(state.data?.pages).toHaveLength(3);
     });
 
     const pageSizes = getCapturedPageSizes();
-    expect(pageSizes.length).toBeGreaterThanOrEqual(2);
-    expect(pageSizes[0]).toBe('200');
     expect(pageSizes[1]).toBe('1000');
+    expect(pageSizes[2]).toBe('1000');
   });
 });