Logos: An Agent Harness on a Cross-Process Bus
2026-08-28 • Artificial Intelligence
Artificial IntelligenceMultiagent Systems
AI summaryⓘ
The authors study how agent systems, which are made by combining different parts during run time, are usually modeled as one big process where if that process fails, everything stops. They show that the formal math behind this modeling doesn’t actually force all parts to be in one process, allowing parts to be separate processes instead. Based on this insight, they build Logos, a system where each part runs in its own process and they only share a simple log of actions, making the system more fault-tolerant. Their tests show that after crashes, sessions can resume without repeating actions and that faults affect fewer parts compared to the traditional single-process approach.
agent systemsruntime compositionspatiotemporal-composability calculusplugin modelprocess failure domainstateless language modelappend-only transcriptROS-like harnessfault tolerancesession resumption
Authors
Hanzhang Jia, Liheng Zeng, Hao Cheng, Yi Gao, Bo Ma
Abstract
Modern agent systems assemble capabilities at runtime, and this dynamic composition has recently received a complete formal treat ment in the spatiotemporal-composability calculus, in which a capability is a component carrying a tracked inverse, and agents are assembled as plugins. This plugin form is carried by a single process sharing one context, a carrier that places all components in one physical failure domain, a fault suspends every component at once, and process death interrupts every session the process hosts. This paper shows that neither the modeling nor the calculus binds an agent to one process, the statelessness of the language model keeps all cross-step state outside the model, and the soundness invariant is defined on the state space alone. These observations condense into four lemmas whose premises are the hypotheses of the calculus and the statelessness of language-model inference. On these lemmas this paper constructs Logos, a ROS-like cross process agent harness in which a plugin is a process and the only shared state is an append-only transcript. Eighty sessions resume with no repeated effect after kills placed at the four boundaries of the tool-call cycle, and a same-fault comparison with a single process reference configuration shows one fault interrupting every co-resident session while under the peer-process construction one fault ends at one node.