fix(jellyfin): make terminal play work with a running app and report progress (#288)

src/shared/jellyfin-cli-response.ts

@@ -0,0 +1,41 @@
+import fs from 'node:fs';
+import path from 'node:path';
+
+// Structured replies the app writes to `--jellyfin-response-path`. The launcher passes a temp
+// path and waits for the file instead of scraping logs, because the command usually runs in an
+// already-running app instance whose output never reaches the launcher's helper process.
+
+export type JellyfinCliLibrary = {
+  id: string;
+  name: string;
+  collectionType: string;
+};
+
+export type JellyfinCliItem = {
+  id: string;
+  title: string;
+  type: string;
+};
+
+export type JellyfinPreviewAuthPayload = {
+  serverUrl: string;
+  accessToken: string;
+  userId: string;
+};
+
+export type JellyfinCliResponse =
+  | { libraries: JellyfinCliLibrary[] }
+  | { items: JellyfinCliItem[] }
+  | { error: string }
+  | JellyfinPreviewAuthPayload;
+
+// Writes via rename so a polling reader never parses a half-written file.
+export function writeJellyfinCliResponse(
+  responsePath: string,
+  response: JellyfinCliResponse,
+): void {
+  fs.mkdirSync(path.dirname(responsePath), { recursive: true });
+  const tempPath = `${responsePath}.${process.pid}.tmp`;
+  fs.writeFileSync(tempPath, JSON.stringify(response), 'utf-8');
+  fs.renameSync(tempPath, responsePath);
+}