Keep the printer's name on statistics after it is deleted (issue #2873)

Every per-printer breakdown resolved the name against the printers that
exist now, so deleting a printer and choosing to keep its prints turned
"Ultron" into "Printer 1" in Prints by Printer, the success-rate and
time-accuracy lists, and Failures by Printer. Archives lose their printer
on that delete as well, so nothing was left to read a name from.

The runs themselves recorded the name they printed on. /archives/stats now
reports the last name each id was known by - taken from the newest run that
has one, so a later name-less row cannot blank it - and failure analysis
falls back to the same thing for ids with no printer left. The client keeps
preferring a live printer's own record, so a rename still shows up straight
away rather than after the next print.

frontend/src/__tests__/pages/StatsPage.test.tsx

@@ -2,7 +2,7 @@
  * Tests for the StatsPage component.
  */
 
-import { describe, it, expect, beforeEach } from 'vitest';
+import { describe, it, expect, beforeEach, afterEach, vi } from 'vitest';
 import { screen, waitFor } from '@testing-library/react';
 import { render } from '../utils';
 import { StatsPage } from '../../pages/StatsPage';
@@ -621,4 +621,46 @@ describe('StatsPage', () => {
       expect(printTime?.querySelector('svg[aria-label]')).toBeNull();
     });
   });
+
+  describe('deleted printers (#2873)', () => {
+    // The per-printer breakdown only renders at half width, and the dashboard
+    // reads its sizes back from localStorage.
+    const halfWidthSuccessRate = JSON.stringify({
+      order: ['success-rate'],
+      hidden: [],
+      sizes: { 'success-rate': 2 },
+    });
+
+    afterEach(() => {
+      vi.mocked(localStorage.getItem).mockReset();
+    });
+
+    it('labels history from a deleted printer with the name it ran under', async () => {
+      vi.mocked(localStorage.getItem).mockImplementation((key: string) =>
+        key === 'bambusy-dashboard-layout-v2' ? halfWidthSuccessRate : null
+      );
+      server.use(
+        http.get('/api/v1/archives/stats', () =>
+          HttpResponse.json({
+            ...mockStats,
+            // Printer 7 was deleted with its prints kept, so it is missing from
+            // /printers and used to show as "Printer 7".
+            prints_by_printer: { '1': 100, '7': 12 },
+            printer_names: { '1': 'Name At The Time', '7': 'Ultron' },
+          })
+        )
+      );
+
+      render(<StatsPage />);
+
+      await waitFor(() => {
+        expect(screen.getByText('Ultron')).toBeInTheDocument();
+      });
+      expect(screen.queryByText('Printer 7')).not.toBeInTheDocument();
+      // A printer that still exists is named from the live record instead, so a
+      // rename shows up without waiting for the next print.
+      expect(screen.getAllByText('X1 Carbon').length).toBeGreaterThan(0);
+      expect(screen.queryByText('Name At The Time')).not.toBeInTheDocument();
+    });
+  });
 });

frontend/src/api/client.ts

@@ -813,6 +813,9 @@ export interface ArchiveStats {
   total_cost: number;
   prints_by_filament_type: Record<string, number>;
   prints_by_printer: Record<string, number>;
+  // Name each printer id was last recorded under in the print log, so history
+  // belonging to a deleted printer keeps its label.
+  printer_names?: Record<string, string>;
   average_time_accuracy: number | null;
   time_accuracy_by_printer: Record<string, number> | null;
   total_energy_kwh: number;

frontend/src/pages/StatsPage.tsx

@@ -1103,7 +1103,18 @@ export function StatsPage() {
   const isRefetching = (isStatsFetching || isArchivesFetching) && !isLoading;
 
   const currency = getCurrencySymbol(settings?.currency || 'USD');
-  const printerMap = new Map(printers?.map((p) => [String(p.id), p.name]) || []);
+  // History outlives the printer that made it: a deleted printer is gone from
+  // `printers`, so its rows fell back to "Printer 1" (#2873). The stats response
+  // carries the name each id was last recorded under; a printer that still
+  // exists overrides it, so a rename shows up straight away.
+  const printerMap = useMemo(
+    () =>
+      new Map<string, string>([
+        ...Object.entries(stats?.printer_names || {}),
+        ...(printers?.map((p) => [String(p.id), p.name] as [string, string]) || []),
+      ]),
+    [stats?.printer_names, printers],
+  );
   const printDates = useMemo(() => archives?.map((a) => a.created_at) || [], [archives]);
 
   if (isLoading) {