Trinity: Human–Agent–Environment Alignment for Embodied Task Planning

Hyungmin Kim, Hobeom Jeon, Dohyung Kim, Jinhyeok Jang, Minsu Jang


Abstract
LLM-based embodied agents are increasingly evaluated on environment-grounded, long-horizon planning, yet existing benchmarks rarely test whether an agent can condition its plans on the specific user it serves. This gap points to a broader limitation in embodied task-planning systems, which often ground their reasoning only in the physical environment while overlooking the diversity of the people they serve. We frame this problem as Planning with Human Attributes (PHA), in which an agent must integrate explicit user information into long-horizon embodied task planning. We introduce Trinity, a benchmark designed to evaluate PHA capabilities. Within Trinity, a single instruction can yield different, equally valid, or even opposing outcomes depending on a user’s personal attributes. Our experiments reveal that standard off-the-shelf in-context learning-based agents commonly fail at the human-grounding component, whether or not they are provided with relevant examples, highlighting a key obstacle for PHA tasks. Beyond benchmarking, we contribute a bottom-up failure-mode analysis that isolates where and why agents break, and we distill it into concrete, model-agnostic design principles for human-agent-environment (HAE) aligned agents. We hope Trinity brings domestic robots a step closer to becoming trusted, socially acceptable partners.
Anthology ID:
2026.findings-emnlp.237
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
4974–5013
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.237/
DOI:
Bibkey:
Cite (ACL):
Hyungmin Kim, Hobeom Jeon, Dohyung Kim, Jinhyeok Jang, and Minsu Jang. 2026. Trinity: Human–Agent–Environment Alignment for Embodied Task Planning. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 4974–5013, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Trinity: Human–Agent–Environment Alignment for Embodied Task Planning (Kim et al., Findings 2026)
Copy Citation:
PDF:
https://aclanthology.org/2026.findings-emnlp.237.pdf