Feedback Blindness: Diagnosing Silent Failures in Closed-Loop Agentic Data-Generation Pipelines

Loc Nguyen, Nguyen Khanh Long, Vu Gia Nam, Nguyen Tran Minh Nhat


Abstract
Closed-loop synthetic-data pipelines combine planning, LLM generation, verification, and deduplication; accepted outputs steer later generation. We study a production pipeline for Vietnamese contact-center compliance data and identify feedback blindness: an internal feedback mechanism stops serving its intended function while every stage completes normally, leaving only downstream metric degradation as evidence. We diagnose four instances: cumulative-count eviction empties a recency window; batch-level deduplication misses candidates scored before any batch member is committed; static boundary exemplars repeatedly anchor generation; and a fixed-size anti-repeat reference set loses informativeness as the dataset grows. We describe architecture-level fixes, mechanism-specific health signals, and a controlled ablation and scaling evaluation. The central lesson is that aggregate duplicate and acceptance rates are insufficient for diagnosis; pipelines should also monitor the feedback mechanisms that produce those outcomes.
Anthology ID:
2026.realm-1.25
Volume:
Proceedings of the Second Workshop for REsearch on Agent Language Models (REALM 2026)
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Ehsan Kamalloo, Nicolas Gontier, Nikolai Rozanov, Maryam Hashemzadeh, Akhil Arora
Venues:
REALM | WS
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
374–381
Language:
URL:
https://aclanthology.org/2026.realm-1.25/
DOI:
Bibkey:
Cite (ACL):
Loc Nguyen, Nguyen Khanh Long, Vu Gia Nam, and Nguyen Tran Minh Nhat. 2026. Feedback Blindness: Diagnosing Silent Failures in Closed-Loop Agentic Data-Generation Pipelines. In Proceedings of the Second Workshop for REsearch on Agent Language Models (REALM 2026), pages 374–381, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Feedback Blindness: Diagnosing Silent Failures in Closed-Loop Agentic Data-Generation Pipelines (Nguyen et al., REALM 2026)
Copy Citation:
PDF:
https://aclanthology.org/2026.realm-1.25.pdf