feat(telemetry): TelemetryService.emit with KST rotation (#7 v0.2.3)

src/main/services/TelemetryService.ts

@@ -0,0 +1,42 @@
+import { mkdir, appendFile } from 'node:fs/promises';
+import { join } from 'node:path';
+import { validateEvent } from './telemetryEvents.js';
+
+const KST_OFFSET_MS = 9 * 60 * 60 * 1000;
+
+function todayKstIso(now: Date): string {
+  const k = new Date(now.getTime() + KST_OFFSET_MS);
+  return new Date(Date.UTC(k.getUTCFullYear(), k.getUTCMonth(), k.getUTCDate()))
+    .toISOString().slice(0, 10);
+}
+
+export interface TelemetryServiceOptions {
+  silent?: boolean;
+}
+
+export type EmitInput =
+  | { kind: 'capture'; payload: { noteId: string; rawTextLength: number; hasMedia: boolean } }
+  | { kind: 'ai_succeeded'; payload: { noteId: string; durationMs: number; attempts: number } }
+  | { kind: 'ai_failed'; payload: { noteId: string; reason: 'unreachable' | 'schema' | 'timeout' | 'other'; attempts: number } };
+
+export class TelemetryService {
+  constructor(
+    private dir: string,
+    private now: () => Date = () => new Date(),
+    private retentionDays: number = 14,
+    private opts: TelemetryServiceOptions = {}
+  ) {}
+
+  async emit(input: EmitInput): Promise<void> {
+    const ts = this.now().toISOString();
+    const event = validateEvent({ ts, kind: input.kind, payload: input.payload });
+    const filePath = join(this.dir, `events-${todayKstIso(this.now())}.jsonl`);
+    try {
+      await mkdir(this.dir, { recursive: true });
+      await appendFile(filePath, JSON.stringify(event) + '\n', 'utf8');
+    } catch (err) {
+      if (this.opts.silent) return;
+      throw err;
+    }
+  }
+}

tests/unit/TelemetryService.test.ts

@@ -0,0 +1,74 @@
+import { describe, it, expect, beforeEach, afterEach } from 'vitest';
+import { mkdtempSync, rmSync, readFileSync, existsSync, readdirSync, writeFileSync } from 'node:fs';
+import { tmpdir } from 'node:os';
+import { join } from 'node:path';
+import { TelemetryService } from '@main/services/TelemetryService.js';
+
+describe('TelemetryService.emit', () => {
+  let dir: string;
+
+  beforeEach(() => { dir = mkdtempSync(join(tmpdir(), 'inkling-telem-')); });
+  afterEach(() => { rmSync(dir, { recursive: true, force: true }); });
+
+  it('appends a JSONL line to events-YYYY-MM-DD.jsonl (KST date)', async () => {
+    // 2026-05-01 12:00 UTC → 2026-05-01 21:00 KST
+    const svc = new TelemetryService(dir, () => new Date('2026-05-01T12:00:00Z'));
+    await svc.emit({ kind: 'capture', payload: { noteId: 'n1', rawTextLength: 5, hasMedia: false } });
+    const file = join(dir, 'events-2026-05-01.jsonl');
+    expect(existsSync(file)).toBe(true);
+    const content = readFileSync(file, 'utf8').trim();
+    const parsed = JSON.parse(content);
+    expect(parsed.kind).toBe('capture');
+    expect(parsed.payload.noteId).toBe('n1');
+    expect(typeof parsed.ts).toBe('string');
+  });
+
+  it('uses KST date even when UTC date differs (around midnight)', async () => {
+    // 2026-05-01 23:30 UTC → 2026-05-02 08:30 KST
+    const svc = new TelemetryService(dir, () => new Date('2026-05-01T23:30:00Z'));
+    await svc.emit({ kind: 'capture', payload: { noteId: 'n2', rawTextLength: 1, hasMedia: false } });
+    expect(existsSync(join(dir, 'events-2026-05-02.jsonl'))).toBe(true);
+  });
+
+  it('appends multiple events to same-day file', async () => {
+    const svc = new TelemetryService(dir, () => new Date('2026-05-01T12:00:00Z'));
+    await svc.emit({ kind: 'capture', payload: { noteId: 'n1', rawTextLength: 5, hasMedia: false } });
+    await svc.emit({ kind: 'ai_succeeded', payload: { noteId: 'n1', durationMs: 100, attempts: 0 } });
+    const lines = readFileSync(join(dir, 'events-2026-05-01.jsonl'), 'utf8').trim().split('\n');
+    expect(lines).toHaveLength(2);
+    expect(JSON.parse(lines[0]!).kind).toBe('capture');
+    expect(JSON.parse(lines[1]!).kind).toBe('ai_succeeded');
+  });
+
+  it('creates telemetry dir if absent', async () => {
+    const fresh = join(dir, 'nested', 'telem');
+    const svc = new TelemetryService(fresh, () => new Date('2026-05-01T12:00:00Z'));
+    await svc.emit({ kind: 'capture', payload: { noteId: 'n1', rawTextLength: 1, hasMedia: false } });
+    expect(existsSync(fresh)).toBe(true);
+  });
+
+  it('rejects malformed event (privacy invariant) — does NOT write file', async () => {
+    const svc = new TelemetryService(dir, () => new Date('2026-05-01T12:00:00Z'));
+    await expect(svc.emit({
+      kind: 'capture',
+      payload: { noteId: 'n1', rawTextLength: 1, hasMedia: false, rawText: 'leak' } as never
+    })).rejects.toThrow();
+    // No file should have been created
+    expect(readdirSync(dir).filter((f) => f.startsWith('events-'))).toEqual([]);
+  });
+
+  it('emit is silent (does not throw) when fs write fails — invariant: telemetry never breaks app', async () => {
+    // Pass a non-writable path; emit should swallow the error.
+    const svc = new TelemetryService(
+      '/proc/0/no-such-thing-readonly',
+      () => new Date('2026-05-01T12:00:00Z'),
+      14,
+      { silent: true }
+    );
+    // Should resolve, not throw
+    await expect(svc.emit({
+      kind: 'capture',
+      payload: { noteId: 'n1', rawTextLength: 1, hasMedia: false }
+    })).resolves.toBeUndefined();
+  });
+});