- sleepCtx helper (NewTimer+Stop) replaces time.After in long backoff sites:
DTLS reconnect (10-30s), captcha 60s ban backoff, lockout sleep. Avoids
long-lived timer leak when ctx cancels mid-wait.
- startIdentityJanitor: prunes expired identityStore entries every 5 min.
Two-phase with TryLock so an in-flight acquireVkIdentity (which can hold
entry.mu for tens of seconds during captcha) never blocks the janitor or
other acquires.
- getYandexCreds: cap ws read loop at 64 messages so a chatty/malformed peer
cannot keep us reading until the 15s deadline burns down.