feat(sync): add sync-hosts store, NDJSON --json mode, and --check to subminer sync

src/shared/sync/sync-events.ts

@@ -0,0 +1,68 @@
+// NDJSON progress protocol emitted by `subminer sync --json` and consumed by
+// the sync UI's launcher client. Keep this file free of Electron/bun imports —
+// it is shared between the launcher (bun) and the app main process (node).
+
+export interface SyncMergeSummary {
+  sessionsMerged: number;
+  sessionsAlreadyPresent: number;
+  activeSessionsSkipped: number;
+  animeAdded: number;
+  videosAdded: number;
+  wordsAdded: number;
+  kanjiAdded: number;
+  subtitleLinesAdded: number;
+  telemetryRowsAdded: number;
+  eventsAdded: number;
+  excludedWordsAdded: number;
+  dailyRollupsCopied: number;
+  monthlyRollupsCopied: number;
+  rollupGroupsRecomputed: number;
+}
+
+export type SyncStage =
+  | 'snapshot-local'
+  | 'snapshot-remote'
+  | 'download'
+  | 'upload'
+  | 'merge-local'
+  | 'merge-remote';
+
+export type SyncProgressEvent =
+  | { type: 'stage'; stage: SyncStage; message: string }
+  | { type: 'merge-summary'; target: 'local' | 'remote'; summary: SyncMergeSummary }
+  | { type: 'remote-output'; text: string }
+  | { type: 'snapshot-created'; path: string }
+  | {
+      type: 'check-result';
+      host: string;
+      sshOk: boolean;
+      remoteCommand: string | null;
+      remoteVersion: string | null;
+      ok: boolean;
+      error: string | null;
+    }
+  | { type: 'result'; ok: boolean; error: string | null };
+
+const EVENT_TYPES = new Set([
+  'stage',
+  'merge-summary',
+  'remote-output',
+  'snapshot-created',
+  'check-result',
+  'result',
+]);
+
+export function parseSyncProgressLine(line: string): SyncProgressEvent | null {
+  const trimmed = line.trim();
+  if (!trimmed.startsWith('{')) return null;
+  let parsed: unknown;
+  try {
+    parsed = JSON.parse(trimmed);
+  } catch {
+    return null;
+  }
+  if (!parsed || typeof parsed !== 'object' || Array.isArray(parsed)) return null;
+  const type = (parsed as { type?: unknown }).type;
+  if (typeof type !== 'string' || !EVENT_TYPES.has(type)) return null;
+  return parsed as SyncProgressEvent;
+}