Handle large WeebCentral catalogs and correct MangaPill checkpoint monitoring

docs/resilience.md

@@ -30,6 +30,12 @@ The recurring Codex check is an additional backstop, not the runtime watchdog.
 | HTTP 401/403/429 or access challenge | Pause affected source lane | No automatic retry/bypass |
 | Active job with no progress for 15 minutes | Sentinel requests cooperative checkpoint-safe retry | One stall recovery; next stall quarantined |
 
+Sentinel only treats an active job as stalled when its checkpoint can be read.
+The scraper resolves source-specific work folders (including MangaPill's
+`mangapill-` prefix) before reporting progress; a missing checkpoint is not
+evidence that downloads stopped. An operator retry resets the job's stall
+recovery count without deleting its partial download.
+
 The daemon remains authoritative: a recovery request includes the observed progress
 fingerprint and is rejected if the job has moved, paused, or is no longer stale.
 Sentinel also observes completed/page counts; a deliberately paused queue is not a