v0.9.5: The Voltron Update — modular architecture, stable IDs, parallelized boot

- Parallelized startup (60s → 15s) via ThreadPoolExecutor
- Adaptive polling engine with ETag caching (no more bbox interrupts)
- useCallback optimization for interpolation functions
- Sliding LAYERS/INTEL edge panels replace bulky Record Panel
- Modular fetcher architecture (flights, geo, infrastructure, financial, earth_observation)
- Stable entity IDs for GDELT & News popups (PR #63, credit @csysp)
- Admin auth (X-Admin-Key), rate limiting (slowapi), auto-updater
- Docker Swarm secrets support, env_check.py validation
- 85+ vitest tests, CI pipeline, geoJSON builder extraction
- Server-side viewport bbox filtering reduces payloads 80%+

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

Former-commit-id: f2883150b5bc78ebc139d89cc966a76f7d7c0408

frontend/src/utils/alertSpread.test.ts

@@ -0,0 +1,71 @@
+import { describe, it, expect } from 'vitest';
+import { spreadAlertItems } from '@/utils/alertSpread';
+
+describe('spreadAlertItems', () => {
+  const makeAlert = (title: string, lat: number, lng: number, cluster_count = 1) => ({
+    title,
+    coords: [lat, lng],
+    cluster_count,
+    alert_level: 3,
+  });
+
+  it('returns empty array for empty input', () => {
+    expect(spreadAlertItems([], 4, new Set())).toEqual([]);
+  });
+
+  it('throws on null input (caller must null-check)', () => {
+    expect(() => spreadAlertItems(null as any, 4, new Set())).toThrow();
+  });
+
+  it('filters out items without coords', () => {
+    const items = [
+      { title: 'No coords', alert_level: 1 },
+      makeAlert('Has coords', 40, -74),
+    ];
+    const result = spreadAlertItems(items, 4, new Set());
+    expect(result.length).toBe(1);
+    expect(result[0].title).toBe('Has coords');
+  });
+
+  it('filters dismissed alerts by alertKey', () => {
+    const items = [
+      makeAlert('Fire in NYC', 40.7, -74.0),
+      makeAlert('Floods in LA', 34.0, -118.2),
+    ];
+    const dismissed = new Set(['Fire in NYC|40.7,-74']);
+    const result = spreadAlertItems(items, 4, dismissed);
+    expect(result.length).toBe(1);
+    expect(result[0].title).toBe('Floods in LA');
+  });
+
+  it('preserves originalIdx for popup selection', () => {
+    const items = [
+      { title: 'Skip me', alert_level: 1 }, // no coords
+      makeAlert('Alert A', 10, 20),
+      makeAlert('Alert B', 30, 40),
+    ];
+    const result = spreadAlertItems(items, 4, new Set());
+    expect(result[0].originalIdx).toBe(1);
+    expect(result[1].originalIdx).toBe(2);
+  });
+
+  it('adds alertKey and showLine properties', () => {
+    const items = [makeAlert('Test Alert', 51.5, -0.1)];
+    const result = spreadAlertItems(items, 4, new Set());
+    expect(result[0]).toHaveProperty('alertKey');
+    expect(result[0]).toHaveProperty('showLine');
+    expect(result[0].alertKey).toContain('Test Alert');
+  });
+
+  it('spreads overlapping alerts apart (offsets are non-zero for stacked items)', () => {
+    // Place 5 alerts at the exact same location — they should be spread apart
+    const items = Array.from({ length: 5 }, (_, i) =>
+      makeAlert(`Alert ${i}`, 40.0, -74.0)
+    );
+    const result = spreadAlertItems(items, 8, new Set()); // zoom 8 = close enough to overlap
+    const hasNonZeroOffset = result.some(
+      (r: any) => Math.abs(r.offsetX) > 1 || Math.abs(r.offsetY) > 1
+    );
+    expect(hasNonZeroOffset).toBe(true);
+  });
+});