ATV — Agent Trajectory Visualizer

A quick-and-dirty view for going off-road through your coding-agent sessions: every project, every session, every turn, live as it happens. Open it in a browser tab or run it as its own desktop window. It reads Claude Code, opencode and Codex sessions straight from where those tools already store them.

Ride

There are two ways to run it. They show the same thing, and can run side by side.

In the browser

python3 server.py        # then open http://127.0.0.1:8765
python3 server.py 9000   # or pick a port

Python 3 standard library only. Nothing to install, nothing to build. Stop it with Ctrl+C.

As a desktop app

ATV in its own window, with its own launcher and alt-tab entry. Linux, and needs Node as well as Python 3.

npm install   # once; Electron is the only dependency
npm start     # starts its own server on a free port and opens the window

Closing the window quits the app. For the sandbox error Electron gives on recent Ubuntu, and for adding ATV to the application menu, see electron/README.md.

The terrain

• Sessions on the left, newest first, with subagent sessions nested under their parent. Each is tinted with its project's colour (a project is a working directory), and the dropdown above filters to one or more projects. A 🔔 marks a session that is waiting for you.
• Trajectory on the right: one line per user message, assistant reply and tool call. Click a line for the full text, tool inputs, output and token details, or hit Expand all. The line under a column's header says where the session's time went (the model, tools, you, background work, idle) and how full its context is; hover it for what each part means. In a wide column a strip under it draws the same as a timeline, with a lane per subagent and the context size as a line; click a stretch to jump to it, or a lane to open that subagent.
• Side by side: Ctrl+click (Cmd+click on macOS) a session to open it in another column, or again to close it. Drag the divider between two columns to resize them. The URL keeps the set of open sessions, so a reload restores it.
• Focus: ⤢ in a column's header shows that session alone, full width. ⤢ again or Esc puts the columns back.
• Live: every open session is tailed every half second (slower while the tab is hidden) and follows the bottom unless you scroll that column up. Open live opens every session still running (within the project filter and search) and closes the rest.
• meta shows the background records hidden by default: system reminders, hook output, attachments.
• details adds each expanded line's raw metadata (model, token usage, stop reason) as JSON.
• raw shows assistant replies and thinking blocks as the markdown text they were written in, instead of rendered.

Where it looks

Tool	Source
Claude Code	~/.claude/projects/**/*.jsonl
opencode	~/.local/share/opencode/opencode.db
Codex	~/.codex/sessions/**/rollout-*.jsonl

Everything is read-only, and the server only listens on localhost, since sessions tend to contain secrets.

Configuration

Optional. To look somewhere else, or in several places, write a JSON config file: see CONFIG.md.