fix: raise default scan limit from 100 to 500, use 999 for initial scans

- Default scanLimit increased to 500 (was 100, missing most channel content)
- First scan (lastCheckedAt === null) uses max(scanLimit, 999) for full catalog
- Discovery timeout scales with limit: 60s base + 30s per 500 items
- Updated platform-settings-repository defaults to match

src/db/repositories/platform-settings-repository.ts

@@ -64,7 +64,7 @@ export async function upsertPlatformSettings(
       subtitleLanguages: data.subtitleLanguages ?? null,
       grabAllEnabled: data.grabAllEnabled ?? false,
       grabAllOrder: data.grabAllOrder ?? 'newest',
-      scanLimit: data.scanLimit ?? 100,
+      scanLimit: data.scanLimit ?? 500,
       rateLimitDelay: data.rateLimitDelay ?? 1000,
       defaultMonitoringMode: data.defaultMonitoringMode ?? 'all',
       createdAt: now,
@@ -79,7 +79,7 @@ export async function upsertPlatformSettings(
         subtitleLanguages: data.subtitleLanguages ?? null,
         grabAllEnabled: data.grabAllEnabled ?? false,
         grabAllOrder: data.grabAllOrder ?? 'newest',
-        scanLimit: data.scanLimit ?? 100,
+        scanLimit: data.scanLimit ?? 500,
         rateLimitDelay: data.rateLimitDelay ?? 1000,
         defaultMonitoringMode: data.defaultMonitoringMode ?? 'all',
         updatedAt: now,
@@ -114,7 +114,7 @@ function mapRow(row: typeof platformSettings.$inferSelect): PlatformSettings {
     subtitleLanguages: row.subtitleLanguages,
     grabAllEnabled: row.grabAllEnabled,
     grabAllOrder: row.grabAllOrder as 'newest' | 'oldest',
-    scanLimit: row.scanLimit ?? 100,
+    scanLimit: row.scanLimit ?? 500,
     rateLimitDelay: row.rateLimitDelay ?? 1000,
     defaultMonitoringMode: (row.defaultMonitoringMode ?? 'all') as MonitoringMode,
     createdAt: row.createdAt,

src/services/scheduler.ts

@@ -207,9 +207,14 @@ export class SchedulerService {
 
       // 3. Load platform settings for scan limit and rate limit delay
       const platformSettingsRow = await getPlatformSettings(this.db, channel.platform);
-      const scanLimit = platformSettingsRow?.scanLimit ?? 100;
+      const baseScanLimit = platformSettingsRow?.scanLimit ?? 500;
       const rateLimitDelay = platformSettingsRow?.rateLimitDelay ?? 1000;
 
+      // First scan (lastCheckedAt === null) → grab full catalog up to 999
+      const scanLimit = channel.lastCheckedAt === null
+        ? Math.max(baseScanLimit, 999)
+        : baseScanLimit;
+
       // 4. Load existing content IDs for dedup gating
       const existingIds = new Set(
         await getRecentContentIds(this.db, channel.id)

src/sources/youtube.ts

@@ -99,6 +99,8 @@ export class YouTubeSource implements PlatformSource {
     const signal = options?.signal;
 
     // ── Phase 1: Fast discovery via --flat-playlist ──
+    // Timeout scales with limit: 60s base + 30s per 500 items
+    const discoveryTimeout = 60_000 + Math.ceil(limit / 500) * 30_000;
     const flatResult = await execYtDlp(
       [
         '--flat-playlist',
@@ -107,7 +109,7 @@ export class YouTubeSource implements PlatformSource {
         `1:${limit}`,
         channel.url,
       ],
-      { timeout: 60_000 }
+      { timeout: discoveryTimeout }
     );
 
     const flatEntries = parseJsonLines(flatResult.stdout);