# WorldLines: Benchmarking and Modeling Long-Horizon Stateful Embodied Agents

Source: [WorldLines: Benchmarking and Modeling Long-Horizon Stateful Embodied Agents](<https://www.sota2.com/research/paper/6a337b82206542251d7c4fc6>)

Collection index: [llms.txt](<https://www.sota2.com/research/llms.txt>)

Data updated: 2026-06-25T06:00:01.773Z

Authors: Yehang Zhang, Jianchong Su, Haojian Huang, Yifan Chang, Tianhao Zhou, Xinli Xu, Yingjie Xu, Yinchuan Li, Zexi Li, Ying-Cong Chen

Published: 2026-06-17T09:26:26.000Z

## Abstract

To assist humans over extended periods in real homes, embodied agents must remember user routines, world states, and past interactions. Existing long-term memory benchmarks mainly evaluate language-centric retrieval and question answering, while embodied benchmarks often focus on short-horizon task execution without testing long-term memory use in dynamic environments. We introduce WorldLines, a project-driven benchmark for long-horizon embodied household assistance. It constructs temporally extended household traces with dialogues, actions, execution feedback, object and device state changes, and converts them into evidence-linked samples for Memory QA and Embodied Task Planning. We further propose ObsMem, an observer-grounded memory framework that maintains visibility-aware memories and action-native state trails for state-aware decisions. Experiments reveal persistent challenges in partial observability, overwritten world states, and translating long-term memory into embodied plans, while ObsMem offers a stronger reference architecture for this setting.

## Recorded benchmark results

A research result applies to its stated dataset, split, metric and evaluation configuration. Compare like-for-like settings, preserve the metric's unit and direction, and distinguish paper-reported results from independent reproduction. The best result recorded here is not a claim of exhaustive, current global coverage.

- [Embodied Planning on WorldLines 21 action-dense samples downstream planning probe](<https://www.sota2.com/research/sota/embodied-planning-on-worldlines-21-action-dense-samples-downstream-planning-probe.md>): Embodied Planning; WorldLines 21 action-dense samples downstream planning probe; Plan Judge: 68.4.

- [Embodied Task Planning on WorldLines Downstream Embodied (planning set)](<https://www.sota2.com/research/sota/embodied-task-planning-on-worldlines-downstream-embodied-planning-set.md>): Embodied Task Planning; WorldLines Downstream Embodied (planning set); Plan Judge Score: 68.4.

- [Memory Question Answering on WorldLines Memory QA samples](<https://www.sota2.com/research/sota/memory-question-answering-on-worldlines-memory-qa-samples.md>): Memory Question Answering; WorldLines Memory QA samples; Judge Score: 71.3.

## Original sources and implementation

[Original paper](<https://arxiv.org/abs/2606.18847>)

[PDF](<https://arxiv.org/pdf/2606.18847.pdf>)