JSONL Viewer v1.3.2: Live-Streaming Agent Traces from Codex, Claude Code & More

Melvin Vivas · X video post · 2026-09-06 · 0:21 · 2,468 views · Open on X

Topics: AI Agents, Tool Use & MCP, LLMOps, Deployment & Monitoring, AI Dev Tools & Productivity · Level: intermediate

Summary

Melvin Vivas announces version 1.3.2 of his open-source JSONL viewer (donvito/jsonl-viewer). The new version can show live, streaming trace views from the Codex, Claude Code, Pi and Hermes coding agents. He recommends it as a way to see what your agents are doing behind the scenes. The tool started as a viewer and editor for .jsonl files, the format often used for fine-tuning and training datasets.

Key points

• JSONL viewer v1.3.2 adds live-streaming trace views for four agents: Codex, Claude Code, Pi and Hermes.
• Coding agents write their session traces as JSONL (one JSON object per line). Reading these traces shows the agent's steps, tool calls and messages.
• Watching traces live helps you debug and understand agent behavior while the agent is running, not only after it finishes.
• The tool is open source on GitHub at donvito/jsonl-viewer. It started as a way to view and edit .jsonl files for fine-tuning and training datasets.
• The same tool covers two jobs: inspecting agent traces (observability) and checking training data quality (fine-tuning).

Resources mentioned

• donvito/jsonl-viewer · repo · github.com · free
  Open-source tool for viewing and editing .jsonl files (fine-tuning datasets) and agent traces from Codex, Claude Code, Pi and Hermes.
  Also in: jsonl-viewer: Live Traces for Codex Orchestrator and Subagents (Melvin Vivas on X · notes), See live Codex traces with the jsonl-viewer tool (Melvin Vivas on X · notes), Melvin Vivas's open-source AI tools, built with Codex (Melvin Vivas on X · notes), Analyzing Codex Traces with jsonl-viewer (Melvin Vivas on X · notes) and 12 more
• OpenAI Codex · tool · openai.com · paid
  OpenAI's coding agent. In the diagram it writes code, fixes review findings and drives the build loop. The creator also used it to make this video.
  Also in: An agent bot that installs and drives Codex on its own (Melvin Vivas on X · notes), Asking a Coder bot to install Codex (Melvin Vivas on X · notes), Sign in with ChatGPT: Setting Usage Limits for Each App (Melvin Vivas on X · notes), Codex Cloud Environments Must Be Saved & Published Before Use (Melvin Vivas on X · notes) and 240 more
• Claude Code · tool · code.claude.com · paid · recommended by both Bashiri Smith & Melvin Vivas
  Build agents and pipelines from the terminal; the guide's main agentic coding tool.
  Also in: Create Claude Code Plugins with /plugin-authoring (Melvin Vivas on X · notes), Claude Code mods: customize behavior and UI with plugins (Melvin Vivas on X · notes), AI Engineer Roadmap Overview: From ML Foundations to RAG, Agents & Ops (Bashiri Smith on Facebook · notes), SkillsBento: Free Plugin Marketplace for Codex and Claude Code (Melvin Vivas on X · notes) and 101 more
• Pi · tool · x.com · free
  A customizable coding agent that can be extended through its Extensions API and connected to several model providers.
  Also in: Sign in with ChatGPT: Setting Usage Limits for Each App (Melvin Vivas on X · notes), Pi reaches v1.0 (Melvin Vivas on X · notes), Claude Code mods: customize behavior and UI with plugins (Melvin Vivas on X · notes), Customizing Your Coding Setup with Pi Coding Agent Extensions (Melvin Vivas on X · notes) and 39 more
• Hermes · tool · hermes-agent.nousresearch.com · free
  The AI agent the creator uses to automate making explainer videos. It is probably Nous Research's Hermes Agent, but the post does not say so.
  Also in: OpenAI DevDay recap: Dots, GPT-6.1 Sol, Codex Cloud, Agents API (Melvin Vivas on X · notes), Coworker: free open-source desktop AI coworker app (Melvin Vivas on X · notes), Agent Monitor: see traces, tokens and costs of your coding agents (Melvin Vivas on X · notes), Coworker: An Open-Source Desktop Agent App for Local and Cloud Models (Melvin Vivas on X · notes) and 13 more

Try this

• Install or run JSONL viewer v1.3.2 from github.com/donvito/jsonl-viewer.
• Open live trace views from Codex, Claude Code, Pi or Hermes to see what your agents are doing behind the scenes.