perf(dynamic-sampling): Batch bulk org rate updates

The bulk org rate edit was calling setFieldValue in a loop for each
project, triggering N separate validations. Use a single atomic
update for all project rates instead, matching the old behavior.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: priscilawebdev

static/app/views/settings/dynamicSampling/projectSampling.spec.tsx

@@ -170,6 +170,44 @@ describe('ProjectSampling', () => {
     );
   });
 
+  it('updates project rates atomically via bulk org rate edit', async () => {
+    const putMock = MockApiClient.addMockResponse({
+      url: '/organizations/org-slug/sampling/project-rates/',
+      method: 'PUT',
+      body: [{id: 1, sampleRate: 0.8}],
+    });
+
+    render(<ProjectSampling />, {organization});
+
+    await waitForProjectRateInput();
+
+    // Activate bulk edit mode
+    await userEvent.click(
+      screen.getByRole('button', {name: 'Proportionally scale project rates'})
+    );
+
+    // Type a new org rate — this should update all project rates in one atomic call
+    const orgRateInput = screen.getAllByRole('spinbutton')[0]!;
+    await userEvent.clear(orgRateInput);
+    await userEvent.type(orgRateInput, '80');
+
+    // The project rate should have been scaled
+    const projectInput = screen.getByRole('spinbutton', {
+      name: 'Sample rate for project-slug',
+    });
+    expect(projectInput).toHaveValue(80);
+
+    // Submit and verify the API call
+    await userEvent.click(screen.getByRole('button', {name: 'Apply Changes'}));
+
+    await waitFor(() => {
+      expect(putMock).toHaveBeenCalledWith(
+        '/organizations/org-slug/sampling/project-rates/',
+        expect.objectContaining({data: [{id: 1, sampleRate: 0.8}]})
+      );
+    });
+  });
+
   it('disables Apply Changes for users without org:write access', async () => {
     const orgWithoutAccess = OrganizationFixture({
       access: [],

static/app/views/settings/dynamicSampling/projectSampling.tsx

@@ -95,6 +95,13 @@ export function ProjectSampling() {
     [form]
   );
 
+  const handleBulkProjectRateChange = useCallback(
+    (updates: Record<string, string>) => {
+      form.setFieldValue('projectRates', prev => ({...prev, ...updates}));
+    },
+    [form]
+  );
+
   // Mirror enableReInitialize: reset the form whenever the server data changes
   useEffect(() => {
     form.reset({projectRates});
@@ -160,6 +167,7 @@ export function ProjectSampling() {
                   editMode={editMode}
                   onEditModeChange={setEditMode}
                   onProjectRateChange={handleProjectRateChange}
+                  onBulkProjectRateChange={handleBulkProjectRateChange}
                   projectRates={currentProjectRates}
                   projectErrors={projectErrors}
                   isLoading={sampleRatesQuery.isPending || sampleCountsQuery.isPending}

static/app/views/settings/dynamicSampling/projectsEditTable.tsx

@@ -23,6 +23,7 @@ interface Props {
   actions: React.ReactNode;
   editMode: 'single' | 'bulk';
   isLoading: boolean;
+  onBulkProjectRateChange: (updates: Record<string, string>) => void;
   onEditModeChange: (mode: 'single' | 'bulk') => void;
   onProjectRateChange: (projectId: string, rate: string) => void;
   period: ProjectionSamplePeriod;
@@ -41,6 +42,7 @@ export function ProjectsEditTable({
   editMode,
   period,
   onEditModeChange,
+  onBulkProjectRateChange,
   onProjectRateChange,
   projectRates,
   projectErrors,
@@ -100,13 +102,11 @@ export function ProjectsEditTable({
         valueSelector: item => formatPercent(item.sampleRate),
       });
 
-      for (const [projectId, rate] of Object.entries(newProjectValues)) {
-        onProjectRateChange(projectId, rate);
-      }
+      onBulkProjectRateChange(newProjectValues);
       setOrgRate(newRate);
       onEditModeChange('bulk');
     },
-    [dataByProjectId, editMode, onProjectRateChange, onEditModeChange, projectRates]
+    [dataByProjectId, editMode, onBulkProjectRateChange, onEditModeChange, projectRates]
   );
 
   const handleBulkEditChange = useCallback((newIsActive: boolean) => {