Crab: A Semantics-Aware Checkpoint/Restore Runtime for Agent Sandboxes

Fuente: arXiv
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Auteurs principaux: Wu, Tianyuan, Chang, Chaokun, Cao, Lunxi, Gao, Wei, Wang, Wei
Format: Preprint
Publié: 2026
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author Wu, Tianyuan
Chang, Chaokun
Cao, Lunxi
Gao, Wei
Wang, Wei
author_facet Wu, Tianyuan
Chang, Chaokun
Cao, Lunxi
Gao, Wei
Wang, Wei
contents Autonomous agents act through sandboxed containers and microVMs whose state spans filesystems, processes, and runtime artifacts. Checkpoint and restore (C/R) of this state is needed for fault tolerance, spot execution, RL rollout branching, and safe rollback-yet existing approaches fall into two extremes: application-level recovery preserves chat history but misses OS-side effects, while full per-turn checkpointing is correct but too expensive under dense co-location. The root cause is an agent-OS semantic gap: agent frameworks see tool calls but not their OS effects; the OS sees state changes but lacks turn-level context to judge recovery relevance. This gap hides massive sparsity: over 75% of agent turns produce no recovery-relevant state, so most checkpoints are unnecessary. Crab (Checkpoint-and-Restore for Agent SandBoxes) is a transparent host-side runtime that bridges this gap without modifying agents or C/R backends. An eBPF-based inspector classifies each turn's OS-visible effects to decide checkpoint granularity; a coordinator aligns checkpoints with turn boundaries and overlaps C/R with LLM wait time; and a host-scoped engine schedules checkpoint traffic across co-located sandboxes. On shell-intensive and code-repair workloads, Crab raises recovery correctness from 8% (chat-only) to 100%, cuts checkpoint traffic by up to 87%, and stays within 1.9% of fault-free execution time.
format Preprint
id arxiv_https___arxiv_org_abs_2604_28138
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Crab: A Semantics-Aware Checkpoint/Restore Runtime for Agent Sandboxes
Wu, Tianyuan
Chang, Chaokun
Cao, Lunxi
Gao, Wei
Wang, Wei
Operating Systems
Artificial Intelligence
Autonomous agents act through sandboxed containers and microVMs whose state spans filesystems, processes, and runtime artifacts. Checkpoint and restore (C/R) of this state is needed for fault tolerance, spot execution, RL rollout branching, and safe rollback-yet existing approaches fall into two extremes: application-level recovery preserves chat history but misses OS-side effects, while full per-turn checkpointing is correct but too expensive under dense co-location. The root cause is an agent-OS semantic gap: agent frameworks see tool calls but not their OS effects; the OS sees state changes but lacks turn-level context to judge recovery relevance. This gap hides massive sparsity: over 75% of agent turns produce no recovery-relevant state, so most checkpoints are unnecessary. Crab (Checkpoint-and-Restore for Agent SandBoxes) is a transparent host-side runtime that bridges this gap without modifying agents or C/R backends. An eBPF-based inspector classifies each turn's OS-visible effects to decide checkpoint granularity; a coordinator aligns checkpoints with turn boundaries and overlaps C/R with LLM wait time; and a host-scoped engine schedules checkpoint traffic across co-located sandboxes. On shell-intensive and code-repair workloads, Crab raises recovery correctness from 8% (chat-only) to 100%, cuts checkpoint traffic by up to 87%, and stays within 1.9% of fault-free execution time.
title Crab: A Semantics-Aware Checkpoint/Restore Runtime for Agent Sandboxes
topic Operating Systems
Artificial Intelligence
url https://arxiv.org/abs/2604.28138