arXiv subjects

Quanzhi Fu

Publications and source records attributed to Quanzhi Fu.

5 recordsLinked to original sources

arXiv2026

ActPlane: Programmable OS-Level Policy Enforcement for Agent Harnesses

AI agents increasingly run in production through harnesses, the software around the LLM, including an engine that enforces safety and effectiveness policies, e.g., 'run tests before committing.' Enforcing these policies requires bridging a semantic gap: policy intent is expressed in underspecified natural language, while enforcement must act on concrete system actions, e.g., which test to run. Many policies also define event ordering or data flow actions. Yet existing approaches fall short. Tool-call guardrails miss system actions that bypass the tool layer, while OS sandboxes control resource access instead of actions, returning opaque errors that confuse the agent. Our key insight is that policy context lives within the agent closest to the task, while enforcement must happen at the OS to cover all execution paths. We introduce ActPlane, a policy engine that lets agents declare policies and enforces them in the OS kernel with semantic feedback and isolation. ActPlane uses a simple information-flow control (IFC) DSL to support cross-event policies. We implement ActPlane with eBPF and evaluate it on policies from the empirical study, coding-task benchmarks, and safety benchmarks. ActPlane improves policy compliance, including on indirect execution paths that tool-call interception cannot observe, with 1.9%-8.4% overhead. ActPlane is at https://github.com/eunomia-bpf/ActPlane

cs.OS↗

arXiv2026

AgentCgroup: Understanding and Controlling OS Resources of AI Agents

AI agents are increasingly deployed in multi-tenant cloud environments, where they execute diverse tool calls within sandboxed containers, each call with distinct resource demands and rapid fluctuations. We present a systematic characterization of OS-level resource dynamics in sandboxed AI coding agents, analyzing 144 software engineering tasks from the SWE-rebench benchmark across two LLM models. Our measurements reveal that (1) OS-level execution (tool calls, container and agent initialization) accounts for 55-60% of end-to-end task latency; (2) memory, not CPU, is the concurrency bottleneck; (3) memory spikes are tool-call-driven with a up to 15.4x peak-to-average ratio; and (4) resource demands are highly unpredictable across tasks, runs, and models. Comparing these characteristics against serverless, microservice, and batch workloads, we identify three mismatches in existing resource controls: a granularity mismatch (container-level policies vs. tool-call-level dynamics), a responsiveness mismatch (user-space reaction vs. sub-second unpredictable bursts), and an adaptability mismatch (history-based prediction vs. non-deterministic stateful execution). We propose AgentCgroup, an intent-driven eBPF-based resource controller that exploits agents ability to declare resource needs and reconstruct execution strategies, using hierarchical cgroup structures aligned with tool-call boundaries, in-kernel enforcement via sched_ext and memcg_bpf_ops, and runtime-adaptive policies. Preliminary evaluation demonstrates improved multi-tenant isolation and reduced resource waste. AgentCgroup is open-source at https://github.com/eunomia-bpf/agentcgroup

cs.OS↗

arXiv2025

Mining the Gold: Student-AI Chat Logs as Rich Sources for Automated Knowledge Gap Detection

With the significant increase in enrollment in computing-related programs over the past 20 years, lecture sizes have grown correspondingly. In large lectures, instructors face challenges on identifying students' knowledge gaps timely, which is critical for effective teaching. Existing classroom response systems rely on instructor-initiated interactions, which limits their ability to capture the spontaneous knowledge gaps that naturally emerge during lectures. With the widespread adoption of LLMs among students, we recognize these student-AI dialogues as a valuable, student-centered data source for identifying knowledge gaps. In this idea paper, we propose QueryQuilt, a multi-agent LLM framework that automatically detects common knowledge gaps in large-scale lectures by analyzing students' chat logs with AI assistants. QueryQuilt consists of two key components: (1) a Dialogue Agent that responds to student questions while employing probing questions to reveal underlying knowledge gaps, and (2) a Knowledge Gap Identification Agent that systematically analyzes these dialogues to identify knowledge gaps across the student population. By generating frequency distributions of identified gaps, instructors can gain comprehensive insights into class-wide understanding. Our evaluation demonstrates promising results, with QueryQuilt achieving 100% accuracy in identifying knowledge gaps among simulated students and 95% completeness when tested on real student-AI dialogue data. These initial findings indicate the system's potential for facilitate teaching in authentic learning environments. We plan to deploy QueryQuilt in actual classroom settings for comprehensive evaluation, measuring its detection accuracy and impact on instruction.

cs.HC↗

arXiv2025

CognixShield: PoV-Guided Vulnerable API Usage Detection in Large Codebases via LLMs

The integration of open-source libraries in Java development introduces severe security risks through vulnerable APIs. Existing program analysis and deep learning tools face the challenge of capturing inter-procedural vulnerability semantics at scale. While LLMs show promise for semantic reasoning, they cannot handle large codebases because of context limits and a lack of vulnerability-specific understanding needed to determine exploitability. We present CognixShield, an LLM-powered framework for detecting vulnerable API usage through three core components. First, semantic-preserving AST-based fragmentation partitions large codebases while maintaining syntactic completeness within LLM context-window limits. Second, vulnerability-aware multi-agent RAG traces relevant program context across these fragments, iteratively assembling security-critical context spanning functions and files. Third, PoV-guided semantic reasoning leverages Proof-of-Vulnerability tests that encode precise triggering conditions and exploitation mechanics for vulnerability determination. CognixShield achieves 84% precision, 95% recall, 84% accuracy, and an 89% F1-score on 57 real-world Java applications, outperforming state-of-the-art tools. Our results show that vulnerability detection requires specialized architectural innovations beyond generic LLM applications.

cs.SE↗

arXiv2021

Packet Routing with Graph Attention Multi-agent Reinforcement Learning

Packet routing is a fundamental problem in communication networks that decides how the packets are directed from their source nodes to their destination nodes through some intermediate nodes. With the increasing complexity of network topology and highly dynamic traffic demand, conventional model-based and rule-based routing schemes show significant limitations, due to the simplified and unrealistic model assumptions, and lack of flexibility and adaption. Adding intelligence to the network control is becoming a trend and the key to achieving high-efficiency network operation. In this paper, we develop a model-free and data-driven routing strategy by leveraging reinforcement learning (RL), where routers interact with the network and learn from the experience to make some good routing configurations for the future. Considering the graph nature of the network topology, we design a multi-agent RL framework in combination with Graph Neural Network (GNN), tailored to the routing problem. Three deployment paradigms, centralized, federated, and cooperated learning, are explored respectively. Simulation results demonstrate that our algorithm outperforms some existing benchmark algorithms in terms of packet transmission delay and affordable load.

cs.AI↗