refactor: centralize provider projections

src/modules/investments/instruments/infrastructure/tbank-candle.mapper.spec.ts

@@ -0,0 +1,19 @@
+import { toSavedCandle } from './tbank-candle.mapper';
+
+describe('T-Bank candle mapping', () => {
+  it('keeps signed nano precision and requires explicit completeness', () => {
+    const input = { time: { seconds: '1767225600' }, close: { units: '0', nano: -1 } };
+    expect(toSavedCandle(input)).toEqual({
+      time: '2026-01-01T00:00:00.000Z', close: '-0.000000001', isComplete: false,
+    });
+    expect(toSavedCandle({ ...input, isComplete: true }).isComplete).toBe(true);
+    expect(input).toEqual({ time: { seconds: '1767225600' }, close: { units: '0', nano: -1 } });
+  });
+  it.each([
+    { close: { units: '1' } },
+    { time: { seconds: 'invalid' }, close: { units: '1' } },
+    { time: { seconds: '1767225600' } },
+  ])('rejects missing or malformed source fields: %j', (input) => {
+    expect(() => toSavedCandle(input)).toThrow('Invalid candle response');
+  });
+});

src/modules/investments/instruments/infrastructure/tbank-candle.mapper.ts

@@ -0,0 +1,18 @@
+import type { TbankCandle } from '../../../../integrations/tbank/tbank.api';
+import type { SavedCandle } from '../domain/candle-coverage';
+
+import { formatDecimal } from '../../../../common/decimal';
+import { decimal } from '../../../../integrations/tbank/decimal';
+import { timestamp } from '../application/instrument-market';
+
+function toSavedCandle(candle: TbankCandle): SavedCandle {
+  const time = timestamp(candle.time);
+  if (!time || !candle.close) throw new Error('Invalid candle response');
+  return {
+    time,
+    close: formatDecimal(decimal(candle.close)),
+    isComplete: candle.isComplete === true,
+  };
+}
+
+export { toSavedCandle };