Coral AI Labs、複数AIエージェントのリアルタイム協調システム「AgentRadio」を発表

As enterprise codebases grow, AI agents tasked with analyzing them are buckling under the weight of long-horizon tasks that require multiple interactions and tool calls. Dividing the work among a team of agents seems like the obvious fix, but it introduces a fatal flaw: most multi-agent systems are not designed for agents to coordinate among themselves mid-task and in real time.

To solve this, researchers at Coral AI Labs and multiple universities introduced AgentRadio, an asynchronous message-passing layer that allows agents to communicate between their execution steps without interrupting their main work. In real-world enterprise applications where subtasks are highly interdependent, this architecture enables agents to make mid-course corrections rather than continue on dead-end paths until a formal review phase.

On a benchmark of long-horizon questions over production repositories, a team of agents powered by AgentRadio nearly doubled task accuracy for four Claude Code agents working independently. It also outmatched single agents running on more advanced models. For AI practitioners, AgentRadio shows that the right coordination structure can outmatch raw compute and model scale.

The challenge of codebase understanding

LLM-based agents are increasingly capable of handling long-horizon tasks that require interacting with different tools and environments. Codebase understanding represents an extreme version of this challenge. It requires an AI agent to build the software, execute it, trace execution paths across multiple files, and synthesize evidence over extended periods.

Under these conditions, single-agent systems usually break down because of a “coverage problem.”

"A single agent follows one serial path through the repository," Xinxing Ren, Caelum Forder, and Peter Carroll, co-authors of the AgentRadio paper, explained to VentureBeat. As its context grows, "the initial plan becomes harder to revise and discoveries made late in the investigation do not always propagate." The model can usually execute individual steps, but "the hard part is keeping every obligation, dependency, and piece of contradictory evidence active across a long investigation."

One benchmark that helps measure AI performance on large codebases is SWE-Atlas QnA. This benchmark consists of long-horizon, natural-language questions over live production repositories. The tasks can’t be solved by just exploring the code. AI agents must run the software and execute multiple commands to find the answers.

According to the research team’s experiments, a single Claude Code instance running on Opus 4.6 resolves just 32.3% of these tasks. Upgrading to a newer, more advanced model like Opus 4.8 only yields a 57.2% success rate.

A natural remedy is to distribute the workload across multiple agents, allowing each to work with a smaller, cleaner context. Multi-agent solutions can provide substantial performance gains when tasks are cleanly decomposable, meaning they can be solved separately and merged at the end.

Codebase understanding, however, is rarely cleanly decomposable. The subtasks are highly interdependent. A critical configuration file or a bug uncovered by one agent can completely rewrite or redirect the entire exploration path of another agent. Because of these dependencies, agents must coordinate, negotiate, and share intermediate discoveries in real time.

Despite this need, asynchronous multi-agent communication is rare. The researchers point out that existing multi-agent systems generally fall into three flawed patterns:

Parallel but isolated: Agents operate simultaneously but do not communicate at all.

Parallel but round-synchronized: Agents can communicate, but only at strict, synchronized round boundaries. This forces agents to stop and wait for one another to finish a round before they can debate or exchange intermediate findings. Round-based systems assume that important discoveries can wait until the next communication phase, which is an expensive assumption when agents are working on interdependent parts of a live system. For example, an agent investigating an API symptom might uncover evidence that invalidates the storage agent's current hypothesis. "If that information waits until both agents finish, the storage investigation may complete along the wrong path," the researchers said.

Asynchrony in adjacent forms: These systems offer limited asynchronous features, such as top-down task dispatching. They don’t have peer-to-peer lateral channels between agents or shared memories that require an agent to actively pause its work to read updates.

In their paper, the researchers point out that the main bottleneck hindering current multi-agent systems is that “an agent that is working cannot also be listening.”

“To our knowledge, no existing system gives concurrently working agents passive awareness of one another over a lateral, natural-language channel,” the researchers write.

How AgentRadio works

To dissolve the mutual exclusion between working and listening, the researchers developed AgentRadio, an asynchronous message-passing layer designed to plug directly into existing coding-agent harnesses.

AgentRadio equips agents with three primitives:

The create_thread primitive opens a conversation between participating agents.

The send_message primitive appends a message to a thread and returns without blocking the sending agent.

The wait_for_mention primitive blocks the process until a message mentioning the caller arrives. It delivers the message along with a full snapshot of all threads so the agent has instant context.

This trio enables agents to have a state of “passive awareness,” where they can continue their primary tasks while passing messages and updating their knowledge in the background.

AgentRadio's code is available under the Apache 2.0 license on GitHub. It is designed to be lightweight, requiring no direct modifications to the underlying agent harnesses like Claude Code or Codex CLI.

The architecture consists of two main parts:

The message server: A standalone process that acts as the central hub, storing all active threads, messages, and mentions for the group of agents.

Harness-side integration: Agents interact with the server using three simple shell scripts, one corresponding to each primitive.

The only strict requirement for the system to work is that the agent harness must be able to run a shell command as a background task. The agents are instructed in their system prompts to keep one watcher running and to send messages through the provided scripts. Running the wait_for_mention script in the background allows the agent to continue its work and receive notifications asynchronously.

To integrate this into an existing stack, a team still needs a "thin adapter that starts the workers, assigns identities, connects them to the shared server, and manages final synthesis," the researchers said. That work sits around the coding agent rather than requiring changes to the underlying model.

AgentRadio in action

To validate the real-world utility of AgentRadio, the researchers tested the framework on 124 tasks from the SWE-Atlas QnA benchmark. The tests covered domains including system design, root-cause analysis, security, and API integration.

The researchers used Claude Opus 4.6 and DeepSeek V4 Pro as the backbone models. For the harness, they evaluated configurations ranging from a single Claude Code agent (B0) to a team of agents with classic division of labor (L1), up to a team of agents using AgentRadio to coordinate asynchronously (L3).

The experimental results showed that the AgentRadio communication architecture outperforms both naive multi-agent setups and raw compute scaling.

While a single Claude Code agent with Opus 4.6 resolved only 32.3% of the tasks, the full AgentRadio setup nearly doubled that metric, resolving 62.1% of the tasks, and surpassed the single agent running on Opus 4.8, which hit 57.2%. It also boosted the DeepSeek V4 Pro results from 29.0% to 50.8%.

To understand how this practically impacts enterprise AI, the paper highlights a real-world task involving a MinIO system. Solving the task required checking per-request server logs, a requirement the agents did not anticipate during their initial planning phase.

In the L2 setting, where agents collaborate but lack asynchronous communications, two agents independently realized they needed these logs while executing commands. Because they could not share this finding mid-execution, one agent gave up privately and the other failed to propose it to the team. During the review phase, the team unanimously agreed on the wrong answer, missing five rubrics.

With AgentRadio activated, the agents made the same mid-execution discovery, but one agent instantly broadcasted the required server-side log evidence to the shared worklog. Because the other agents were passively listening, they absorbed this new evidence immediately. This real-time coordination transformed a failing score into a perfect 16 out of 16.

"The useful distinction is timing," the researchers said. "The team did not need another agent or another review round. It needed one agent's discovery to reach the right peers before its operational value expired."

The researchers note that the same pattern appears in enterprise incident work. For example, an agent investigating an API symptom might uncover evidence that invalidates the storage agent's current hypothesis. If that information waits until both agents finish, the storage investigation may complete along the wrong path. “Passive awareness lets the second agent incorporate the contradiction at its next work step without interrupting a command already in progress,” they said.

The cost and complexity of coordination

AgentRadio requires a fixed multi-agent team budget, which inherently multiplies the token cost. The researchers acknowledge that the "tax is real," noting that average API spend rose from $2.96 per task for one Opus agent to $19.45 for the full AgentRadio stack.

However, raw scale does not equal performance. When researchers compute-matched the test by spending $17.76 on six independent Opus runs, the models only resolved 37.9% of tasks, compared with 62.1% for AgentRadio. This suggests that AgentRadio's architecture is a structural win, not just a brute-force scale win. Teams should still be aware of inter-agent churn. "Communication can redirect an agent toward better evidence, and it can also distract an agent from a valid path," the researchers warned.

A fixed multi-agent team should not become the default response to every engineering task. The more useful test to determine if a multi-agent setup is required is whether the task contains "responsibility breakpoints," the researchers said. These are places "where a competent engineer would involve another person because the work crosses an ownership boundary, needs an independent hypothesis, or carries enough risk to justify separate verification."

“Coordination is a strong fit when the task can be decomposed, the resulting parts remain interdependent, the single-agent success rate is unreliable, and an incomplete answer has a meaningful downstream cost,” the researchers said. Examples include repository-wide architecture questions, unfamiliar legacy systems, cross-service incident investigation, security analysis, dependency migrations, and multi-module refactors.

Conversely, a single agent remains the cleaner choice for “bounded, local, and reversible work,” such as a known one-file change or boilerplate generation.

“Use one agent while one context can still own the problem honestly,” the researchers said. “Introduce another responsibility when the existing agent would otherwise need to compress away evidence, cross an independent ownership boundary, or verify its own high-impact conclusion.”

From research to commercialization: Coral Code

While AgentRadio serves as a controlled research implementation using a fixed four-agent team and a five-phase protocol, the underlying principles are being adapted into a commercial product called Coral Code.

Instead of a rigid, multi-agent protocol applied to every ticket, Coral Code works from the bottom up. An engineer begins with their existing coding agent, and Coral introduces repository-scoped investigation, specialist responsibility, and communication only when the emerging evidence justifies it. "Coral packages the operational concerns around the tools engineers already use, providing the repository context, scoped specialists, communication, and evidence layer around the harness rather than inside it," the researchers said.

This dynamic approach optimizes costs by targeting the relevant unit: the cost of a completed, reviewable outcome.

The future of autonomous software engineering

While AgentRadio provides a major upgrade to agent orchestration, there are still hurdles to overcome. One major bottleneck that the researchers pointed out to is “attention governance and verification.”

“Passive awareness makes communication available during execution. It does not decide which agents should exist, which discovery deserves an interruption, who should receive it, or when the evidence is strong enough to revise the plan,” the researchers said. If every agent receives every update, the communication layer becomes noise. If several agents share the same bad assumption, faster communication can spread the error.

For example, in one of the case studies in the paper that involved the Grafana platform, four of nine rubrics required negative conclusions, such as observing that a datasource picker did not select automatically. The agents ran the relevant tests, yet none formed the missing negative hypothesis. Both configurations failed the four rubrics.

“Passive awareness can distribute an idea that somebody develops. It cannot supply a conception that never appears anywhere in the team,” the researchers said.

As task durations stretch longer, communication and coordination become critical. "The next generation of systems… needs adaptive responsibility assignment, evidence-aware routing, conflict resolution, explicit cost limits, permissions, recovery, and clear human escalation points," the researchers note. Most importantly, it requires durable provenance so engineering leads can inspect which agent made a claim and why an action was accepted.

"Longer-running agents make communication more important. They also make accountability much harder to fake," they said.