This systematic review surveys advances in conversational AI from 2015 to 2025, focusing on the emergence of modular multi-agent architectures, hierarchical reinforcement learning, and self- evolving agents. A quantitative synthesis of 63 studies indicates that memory-augmented, long- horizon planners improve task success rates by approximately 30% over flat policies, while meta- learning and lifelong learning approaches halve sample complexity in data-scarce domains. Despite these gains, current systems remain brittle under distribution shifts, lack principled safety guarantees, and provide few benchmarks for diagnosing co-adaptive failure modes in mission-critical applications.

Multi-Agent Systems, Conversational AI, Adaptive Dialogue, Hierarchical Planning

J. Li, M. Zhang, N. Li, D. Weyns, Z. Jin, and K. Tei. Generative ai for self-adaptive systems: State of the art and research roadmap. ACM Transactions on Autonomous and Adaptive Systems, 19(3):1–60, 2024.

Z. Tao, T.E. Lin, X. Chen, H. Li, Y. Wu, Y. Li, Z. Jin, F. Huang, D. Tao, and J. Zhou. A survey of the self-evolution of large language models, 2024.

T. Guo, X. Chen, Y. Wang, R. Chang, S. Pei, N.V. Chawla, O. Wiest, and X. Zhang. Large language model-based multi-agents: A survey of progress and challenges, 2024.

Z. Chu, Y. Wang, F. Zhu, L. Yu, L. Li, and J. Gu. Professional agents: Evolving large language models into autonomous experts with human-level competencies, 2024.

N. Nezamoddini and A. Gholami. A survey of adaptive multi-agent networks and their applications in smart cities.

Smart Cities, 5(1):318–347, 2022.

C. Zhang, S. He, J. Qian, B. Li, L. Li, S. Qin, Y. Kang, M. Ma, G. Liu, Q. Lin, and S. Rajmohan. Large language model-brained gui agents: A survey, 2024.

Omdia. Why rigorous definitions matter in the agentic ai conversation, 2025. Accessed: 2025-07-02.

B. Liu, X. Li, J. Zhang, J. Wang, T. He, S. Hong, H. Liu, S. Zhang, K. Song, K. Zhu, and Y. Cheng. Advances and challenges in foundation agents: From brain-inspired intelligence to evolutionary, collaborative, and safe systems, 2025.

A. Kalyuzhnaya, V. Vorona, N. O. Nikitin, N. Chichkova, K. Fatkhiev, S. Mityagin, Y. Aksenkin, A. Boukhanovsky,

K. Fedorin, E. Lutsenko, and A. Getmanov. Llm agents for smart city management: Enhancing decision support through multi-agent ai systems, 2025.

J. Liao, M. Wen, J. Wang, and W. Zhang. Marft: Multi-agent reinforcement fine-tuning, 2025.

Z. Feng, R. Xue, L. Yuan, Y. Yu, N. Ding, M. Liu, B. Gao, J. Sun, and G. Wang. Multi-agent embodied ai: Advances and future directions, 2025.

G. Liu, P. Zhao, L. Liu, Y. Guo, H. Xiao, W. Lin, Y. Chai, Y. Han, S. Ren, H. Wang, and X. Liang. Llm-powered gui agents in phone automation: Surveying progress and prospects, 2025.

Y. Du, W. Huang, D. Zheng, Z. Wang, S. Montella, M. Lapata, K.F. Wong, and J.Z. Pan. Rethinking memory in ai: Taxonomy, operations, topics, and future directions, 2025.

S. Hu, T. Huang, G. Liu, R.R. Kompella, F. Ilhan, S.F. Tekin, Y. Xu, Z. Yahn, and L. Liu. A survey on large language model-based game agents, 2024.

Y. Liu, X. Cao, T. Chen, Y. Jiang, J. You, M. Wu, X. Wang, M. Feng, Y. Jin, and J. Chen. A survey of embodied ai in healthcare: Techniques, applications, and opportunities, 2025.

W. Liu, J. Qin, X. Huang, X. Zeng, Y. Xi, J. Lin, C. Wu, Y. Wang, L. Shang, R. Tang, and D. Lian. The real barrier to llm agent usability is agentic roi, 2025.

J. Yu, Y. Qin, H. Che, Q. Liu, X. Wang, P. Wan, D. Zhang, and X. Liu. Position: Interactive generative video as a next-generation game engine, 2025.

A. Chen, Y. Wu, J. Zhang, S. Yang, J.T. Huang, K. Wang, W. Wang, and S. Wang. A survey on the safety and security threats of computer-using agents: Jarvis or ultron?, 2025.

Yingxuan Yang, Huacan Chai, Shuai Shao, Yuanyi Song, Siyuan Qi, Renting Rui, and Weinan Zhang. Agentnet: Decentralized evolutionary coordination for llm-based multi-agent systems. arXiv preprint, 2025. Introduces a decentralized RAG-based DAG coordination framework.

Ariel Flint Ashery, Andrea Baronchelli, et al. Emergent social conventions and collective bias in llm populations.

Science Advances, 2025. Demonstrates spontaneous emergent communication among agent populations.

Ali Baheri and Cecilia O. Alm. Hierarchical neuro-symbolic decision transformer. arXiv preprint, 2025. Combines symbolic planning with transformer-based policies for long-horizon tasks.

S. Du, J. Zhao, J. Shi, Z. Xie, X. Jiang, Y. Bai, and L. He. A survey on the optimization of large language model-based agents, 2025.

J. Zheng, C. Shi, X. Cai, Q. Li, D. Zhang, C. Li, D. Yu, and Q. Ma. Lifelong learning of large language model-based agents: A roadmap, 2025.

Z. Wang, K. Wang, Q. Wang, P. Zhang, L. Li, Z. Yang, K. Yu, M.N. Nguyen, L. Liu, E. Gottlieb, and M. Lam. Ragen: Understanding self-evolution in llm agents via multi-turn reinforcement learning, 2025.

F. Tang, H. Xu, H. Zhang, S. Chen, X. Wu, Y. Shen, W. Zhang, G. Hou, Z. Tan, Y. Yan, and K. Song. A survey on

(m) llm-based gui agents, 2025.

Z.Z. Li, D. Zhang, M.L. Zhang, J. Zhang, Z. Liu, Y. Yao, H. Xu, J. Zheng, P.J. Wang, X. Chen, and Y. Zhang. From system 1 to system 2: A survey of reasoning in large language models, 2025.

Y. Deng, Y. Li, B. Ding, and W. Lam. Leveraging long short-term user preference in conversational recommenda- tion via multi-agent reinforcement learning, 2023.

L. Tudor Car, D. A. Dhinagaran, B. M. Kyaw, T. Kowatsch, S. Joty, Y.-L. Theng, and R. Atun. Conversational agents in health care: Scoping review and conceptual analysis, 2020.

O. Fayayola, O. Olorunfemi, and P. Shoetan. Data privacy and security in it: A review of techniques and challenges, 2024.

OECD. Oecd ai principles: Promoting trustworthy ai. https://oecd.ai/en/ai-principles, 2024. Accessed July 2025.

UNESCO. Recommendation on the ethics of artificial intelligence. https://www.unesco.org/en/ artificial-intelligence/recommendation-ethics, 2021. Accessed July 2025.

OECD. Transparency and explainability (principle 1.3). https://oecd.ai/en/dashboards/ ai-principles/P7, 2024. Accessed July 2025.

UNESCO. Ai and the judiciary: Balancing innovation with integrity. https://www.unesco.org/en/ articles/ai-and-judiciary-balancing-innovation-integrity, 2025. Accessed July 2025.

Alejandro Barredo Arrieta et al. Explainable artificial intelligence (xai): Concepts, taxonomies, opportunities and challenges toward responsible ai. https://arxiv.org/abs/1910.10045, 2019. Accessed July 2025.

Michael Nasir and Abdul Bamako. Transparent justice: Legal frameworks for explainable ai in law. https://www.researchgate.net/publication/392312198_Transparent_Justice_Legal_ Frameworks_for_Explainable_AI_in_Law, 2025. Accessed July 2025.

ISO/TC 159/SC 4 Ergonomics of human–system interaction committee. Iso 9241-210:2019 – ergonomics of human–system interaction – part 210: Human-centred design for interactive systems. International Standard, 2019. Prepared by ISO/TC 159/SC 4; withdrawal of ISO 13407.

IEEE. Ieee 7000-2021 – model process for addressing ethical concerns during system design. IEEE Standard, 2021. Published by IEEE; authored by committee.

Alan Chan, Rebecca Salganik, Alva Markelius, Chris Pang, Nitarshan Rajkumar, Dmitrii Krasheninnikov, Lauro Langosco, Zhonghao He, Yawen Duan, Micah Carroll, Michelle Lin, Alex Mayhew, Katherine Collins, Maryam Molamohammadi, John Burden, Wanru Zhao, Shalaleh Rismani, Konstantinos Voudouris, Umang Bhatt, Adrian Weller, David Krueger, and Tegan Maharaj. Harms from increasingly agentic algorithmic systems. arXiv, 2023. Discusses distributed responsibility and emergent harms in agentic systems.

Stephanie Baker and Wei Xiang. Explainable ai is responsible ai: How explainability creates trustworthy and socially responsible artificial intelligence. arXiv, 2023. Connects XAI with system-level trust and explainability.

AI Now Institute. Ai now 2018 report. Report, 2018. Recommends human-in-loop control and full-supply-chain transparency in AI systems.

ACM FAccT Community. Acm facct 2025 focus areas. Conference Position Statement, 2025. Highlights importance of HCI, decision support, human-in-loop, and surveillance practices.