chore: use channel file for default, then back to 'stable'

src/update.ts

@@ -268,17 +268,21 @@ export class Updater {
     return current === updated
   }
 
-  private async determineChannel(version:string|undefined): Promise<string> {
+  private async determineChannel(version?:string): Promise<string> {
+    const channelPath = path.join(this.config.dataDir, 'channel')
+
+    const channel = fs.existsSync(channelPath) ? (await fs.readFile(channelPath, 'utf8')).trim() : 'stable'
+
     try {
-      const {body} = await HTTP.get(`https://registry.npmjs.org/${this.config.pjson.name}/`)
-      const tags = (body as {'dist-tags': Record<string, string>})['dist-tags']
-      const tag = Object.keys(tags).find(v => tags[v] === version) ?? 'stable'
+      const {body} = await HTTP.get<{'dist-tags':Record<string, string>}>(`https://registry.npmjs.org/${this.config.pjson.name}/`)
+      const tags = body['dist-tags']
+      const tag = Object.keys(tags).find(v => tags[v] === version) ?? channel
       // convert from npm style tag defaults to OCLIF style
       if (tag === 'latest') return 'stable'
       if (tag === 'latest-rc') return 'stable-rc'
       return tag
     } catch {
-      return 'stable'
+      return channel
     }
   }