[2605.21997] The Log is the Agent: Event-Sourced Reactive Graphs for Auditable, Forkable Agentic Systems

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arXiv:2605.21997 (cs)

[Submitted on 21 May 2026]

Title:The Log is the Agent: Event-Sourced Reactive Graphs for Auditable, Forkable Agentic Systems

Authors:Yohei Nakajima<br>View a PDF of the paper titled The Log is the Agent: Event-Sourced Reactive Graphs for Auditable, Forkable Agentic Systems, by Yohei Nakajima

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Abstract:Most agent frameworks are built around the language model: a conversation loop comes first, then tools, then rules, and finally a logging layer bolted on for observability, with state persisted as retrievable "memory." We describe ActiveGraph, a runtime that inverts this arrangement. The append-only event log is the source of truth; the working graph is a deterministic projection of that log; and behaviors--ordinary functions, classes, LLM-backed routines, or logic attached to typed edges--react to changes in the graph and emit new events. No component instructs another; coordination happens entirely through the shared graph. This single design decision yields three properties that retrieval-and-summarization memory systems do not provide: deterministic replay of any run from its log, cheap forking that branches a run at any event without re-executing the shared prefix, and end-to-end lineage from a high-level goal down to the individual model call that produced each artifact. We present the architecture, a determinism contract that makes replay sound, and a worked diligence example whose full causal structure is reconstructable from the log alone. We discuss--without claiming to demonstrate--why this substrate is unusually well suited to self-improving agents, and how it extends the BabyAGI lineage and prior graph-memory research.

Comments:<br>11 pages, 1 figure. Open-source Apache-2.0 implementation with reproducible quickstart demo, deterministic replay, fork-and-diff, and lineage tracing

Subjects:

Artificial Intelligence (cs.AI); Multiagent Systems (cs.MA)

Cite as:<br>arXiv:2605.21997 [cs.AI]

(or<br>arXiv:2605.21997v1 [cs.AI] for this version)

https://doi.org/10.48550/arXiv.2605.21997

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arXiv-issued DOI via DataCite

Submission history<br>From: Yohei Nakajima [view email]<br>[v1]<br>Thu, 21 May 2026 04:55:38 UTC (55 KB)

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