feat: deepresearch a2a-go agent

[yarolegovich]

Overview

A multi-agent system that performs deep research on a given topic. The project showcases way of implementing the standard SDK interfaces for integrating with various popular infra components like MySQL and NATS.

Built using a2a-go and adk.

• Horizontally scalable cluster of different agent types: orchestrator, researcher, analyzer, and synthesizer.
• MySQL for task indexing and Jetstream for event persistence.
• Push notification sender for signaling subtask completion to the orchestrator.
• NATS for work distribution, event and push notification delivery.
• Retryable execution with state checkpointing.

Details

Orchestrator agents handle client requests:

1. Uses LLM planner to decompose a question into subtasks.
2. Dispatches them to a cluster of researcher agents with returnImmediately: true.
3. Waits for results using NATS-based push notifications.
4. Invokes an analyzer to find contradictory topics for a follow-up research.
5. Initiates the follow-up research.
6. Invokes a synthesizer to generate a final report.

If an orchestrator crashes, the state machine replays its event stream from the NATS STATES stream to recover which stages were dispatched and which completed, then resumes from where it left off.

Orchestrator never loads large task contents into memory and instead uses task references when communicating with synthesizer and analyzer. The final report is returned to a user a reference.

Push notifications allow orchestrator to limit the number of open long-lived connections and avoid subtask status polling.

Also moved the old non-a2a-go code under samples/go to "archived" directory and separated go-linting because superlint errors did not make sense.

[gemini-code-assist]

Code Review

This pull request introduces a multi-agent deep research system utilizing the A2A protocol, featuring orchestrator, researcher, analyzer, and synthesizer agents, with NATS JetStream for event sourcing and MySQL for task persistence. Key feedback highlights several critical issues: a compilation error in the cluster client due to an invalid sync.WaitGroup.Go call, a database query error in indexing.go using status instead of state, and a missing agent column in the test database schema. Additionally, the review points out a race condition in eventqueue.go, a non-deterministic task ordering bug in taskstore.go, a DOM-based XSS vulnerability in the report page, and potential nil pointer panics in the planner. Defensive checks for empty subtasks in the orchestrator and minor documentation/typo fixes are also recommended.

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