debug: yt-dlp live-check hatalarını /status'ta görünür kıl

yt-dlp hem "kanal canlı değil" hem de gerçek bir hata (ağ engeli,
bot tespiti, extractor kırılması) durumunda non-zero exit code
veriyor; ikisi ayırt edilemiyordu. Son hata mesajı artık kanal
başına saklanıp GET /status içinde lastPollError alanında dönüyor.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

apps/api-daemon/src/server.ts

@@ -1,6 +1,7 @@
 import express from "express";
 import { prisma } from "@streamclipper/db";
 import { env } from "./env";
+import { lastPollErrors } from "./youtubePolling";
 
 export function startServer() {
   const app = express();
@@ -26,6 +27,7 @@ export function startServer() {
         lastCheckedAt: c.lastCheckedAt,
         recording: c.sessions.length > 0,
         activeSessionId: c.sessions[0]?.id ?? null,
+        lastPollError: lastPollErrors.get(c.channelId) ?? null,
       })),
     });
   });

apps/api-daemon/src/youtubePolling.ts

@@ -7,6 +7,14 @@ import { sendTelegramMessage } from "./telegram";
 
 const execFileAsync = promisify(execFile);
 
+/**
+ * yt-dlp exits non-zero both when a channel isn't live and when the check
+ * itself fails (network block, bot detection, extractor breakage). Those two
+ * cases must not be indistinguishable, so the last failure per channel is
+ * kept here and surfaced via GET /status for debugging.
+ */
+export const lastPollErrors = new Map<string, string>();
+
 /**
  * Live detection goes through yt-dlp itself instead of the YouTube Data API.
  * `search.list?eventType=live` costs 100 quota units per call against a
@@ -23,10 +31,12 @@ async function findLiveVideoId(channelId: string): Promise<string | null> {
       ["--simulate", "--no-warnings", "--print", "%(id)s", liveUrl],
       { timeout: 20_000 },
     );
+    lastPollErrors.delete(channelId);
     const videoId = stdout.trim().split("\n")[0];
     return videoId || null;
-  } catch {
-    // yt-dlp exits non-zero when the channel isn't currently live
+  } catch (err) {
+    const message = err instanceof Error ? err.message : String(err);
+    lastPollErrors.set(channelId, message.slice(0, 500));
     return null;
   }
 }