agent-flow-visualization

SKILL.md

Agent Flow

Skill by ara.so — Daily 2026 Skills collection.

Agent Flow is a VS Code extension that provides real-time visualization of Claude Code agent orchestration. It renders agent execution as an interactive node graph, showing tool calls, branching, subagent coordination, and timing — turning Claude Code's black-box execution into a transparent, debuggable flow.

Installation

Via VS Code Marketplace

Open VS Code Extensions (Cmd+Shift+X)

Search for Agent Flow by simon-p

Click Install

Or install directly: marketplace.visualstudio.com/items?itemName=simon-p.agent-flow

Requirements

VS Code 1.85 or later

Claude Code CLI installed and accessible

Node.js (for Claude Code)

Quick Start

# 1. Open Command Palette
Cmd+Shift+P (Mac) / Ctrl+Shift+P (Win/Linux)

# 2. Run the command
> Agent Flow: Open Agent Flow

# 3. Start a Claude Code session in your workspace
# Agent Flow auto-detects it and begins streaming

Or use the keyboard shortcut:

Mac: Cmd+Alt+A

Win/Linux: Ctrl+Alt+A

Commands

Command
Description

Agent Flow: Open Agent Flow
Open visualizer in current editor column

Agent Flow: Open Agent Flow to Side
Open in a side editor column

Agent Flow: Connect to Running Agent
Manually connect to a specific agent session

Agent Flow: Configure Claude Code Hooks
Set up Claude Code hooks for live event streaming

Configuration

Settings available in VS Code settings (settings.json):

{
  // Path to a JSONL event log file to watch/replay
  "agentVisualizer.eventLogPath": "/path/to/agent-events.jsonl",

  // Auto-open the visualizer when an agent session starts
  "agentVisualizer.autoOpen": true,

  // Development server port (0 = production mode, use built assets)
  "agentVisualizer.devServerPort": 0
}

Auto-Open on Agent Start

// settings.json
{
  "agentVisualizer.autoOpen": true
}

Claude Code Hooks Setup

Agent Flow uses Claude Code's hook system for zero-latency event streaming. Hooks are configured automatically on first open, but you can reconfigure manually.

Automatic Configuration

Run from Command Palette:

> Agent Flow: Configure Claude Code Hooks

Manual Hook Configuration

If you need to configure hooks manually, Agent Flow starts a local HTTP server that receives events. The hooks forward Claude Code lifecycle events (tool calls, responses, session start/end) to the extension.

Claude Code hooks are configured in ~/.claude/settings.json or project-level .claude/settings.json:

{
  "hooks": {
    "PreToolUse": [
      {
        "matcher": ".*",
        "hooks": [
          {
            "type": "command",
            "command": "curl -s -X POST http://localhost:PORT/hook -H 'Content-Type: application/json' -d @-"
          }
        ]
      }
    ],
    "PostToolUse": [
      {
        "matcher": ".*",
        "hooks": [
          {
            "type": "command",
            "command": "curl -s -X POST http://localhost:PORT/hook -H 'Content-Type: application/json' -d @-"
          }
        ]
      }
    ]
  }
}

Agent Flow manages this configuration automatically — prefer using the command palette command.

JSONL Event Log Mode

For replaying past sessions or watching log files generated outside VS Code:

// settings.json
{
  "agentVisualizer.eventLogPath": "${workspaceFolder}/logs/agent-session.jsonl"
}

Agent Flow tails the file and visualizes events as they arrive. Use this for:

Post-hoc debugging of agent runs

Sharing agent execution recordings with teammates

CI/CD pipeline agent monitoring

JSONL Event Format

Each line in the log file is a JSON event object:

{"type":"session_start","sessionId":"abc123","timestamp":"2026-03-21T10:00:00Z","model":"claude-opus-4-5"}
{"type":"tool_use","sessionId":"abc123","toolName":"bash","input":{"command":"ls -la"},"timestamp":"2026-03-21T10:00:01Z"}
{"type":"tool_result","sessionId":"abc123","toolName":"bash","output":"total 48\n...","timestamp":"2026-03-21T10:00:02Z"}
{"type":"message","sessionId":"abc123","role":"assistant","content":"I can see the files...","timestamp":"2026-03-21T10:00:03Z"}

Multi-Session Support

Agent Flow tracks multiple concurrent Claude Code sessions with tabs. Each session gets its own visualization canvas.

# Start multiple Claude Code sessions in different terminals
# Each appears as a separate tab in Agent Flow
# Click tabs to switch between session graphs

Interactive Canvas Features

Navigation

Pan: Click and drag on empty canvas

Zoom: Scroll wheel / pinch gesture

Select node: Click any agent or tool call node to inspect details

Reset view: Double-click empty canvas

Node Types in the Graph

Node Type
Visual
Description

Agent/Subagent
Circle
Claude instance making decisions

Tool Call
Rectangle
Individual tool invocation (bash, read_file, etc.)

Tool Result
Rectangle (dashed)
Output returned from tool

Branch
Diamond
Decision point spawning subagents

Return
Arrow
Subagent returning result to parent

Panels

Timeline: Chronological view of all events with durations

Transcript: Full message history between agent and tools

File Heatmap: Which files received the most attention

Contributing / Development Setup

git clone https://github.com/patoles/agent-flow
cd agent-flow
npm install

# Build the extension
npm run build

# Watch mode for development
npm run watch

# Run with dev server (hot reload)
# Set in settings: "agentVisualizer.devServerPort": 3000
npm run dev

Extension Structure

agent-flow/
├── src/
│   ├── extension.ts          # VS Code extension entry point
│   ├── hookServer.ts         # HTTP server receiving Claude Code hook events
│   ├── sessionManager.ts     # Manages multiple agent sessions
│   ├── webviewProvider.ts    # Webview panel management
│   └── logWatcher.ts         # JSONL file tail watcher
├── webview/
│   ├── src/
│   │   ├── App.tsx           # Main React app
│   │   ├── Graph.tsx         # Node graph canvas (likely D3 or React Flow)
│   │   ├── Timeline.tsx      # Timeline panel
│   │   └── Transcript.tsx    # Message transcript panel
│   └── package.json
└── package.json              # Extension manifest

Common Patterns

Pattern: Debug a Failing Agent Run

Open Agent Flow (Cmd+Alt+A)

Run your Claude Code command that's failing

Watch the graph — look for:

Red/error nodes indicating failed tool calls

Unexpected branching

Loops (agent retrying the same tool)

Click the failed tool node to inspect input/output

Check the Timeline panel for which tool call took unexpectedly long

Pattern: Replay a Saved Session

# Save Claude Code output to JSONL during a run
# (depends on your Claude Code version/config)
claude --output-format jsonl > session-$(date +%s).jsonl

# Point Agent Flow at it

// .vscode/settings.json (project-level)
{
  "agentVisualizer.eventLogPath": "./logs/session-1234567890.jsonl"
}

Pattern: Auto-Visualize All Agent Sessions

// settings.json
{
  "agentVisualizer.autoOpen": true
}

Now every time a Claude Code session starts in your workspace, Agent Flow opens automatically.

Pattern: Side-by-Side Coding and Visualization

# Open Agent Flow to side so you can code and watch simultaneously
Cmd+Shift+P > Agent Flow: Open Agent Flow to Side

This opens the visualizer in a split editor, keeping your code files accessible in the main editor group.

Troubleshooting

Agent Flow doesn't detect my Claude Code session

Verify Claude Code is running in the same workspace folder

Check that hooks are configured: run Agent Flow: Configure Claude Code Hooks

Verify the hook server is running — look for "Agent Flow hook server listening" in the Output panel (View > Output > Agent Flow)

Try Agent Flow: Connect to Running Agent to manually specify the session

Hooks aren't forwarding events

# Test the hook server manually
curl -X POST http://localhost:PORT/hook \
  -H 'Content-Type: application/json' \
  -d '{"type":"test","sessionId":"test123"}'

Check VS Code Output panel for the correct PORT value.

Graph is empty / not updating

Check agentVisualizer.eventLogPath — if set, Agent Flow reads from file instead of hooks

Clear the setting if you want live hook-based streaming:
{ "agentVisualizer.eventLogPath": "" }

Reload VS Code window (Cmd+Shift+P > Developer: Reload Window)

Extension not loading

# Check VS Code version meets requirement
code --version
# Must be 1.85 or later

# Check extension is enabled
# Extensions panel > search "Agent Flow" > verify enabled

Multiple sessions showing in wrong tabs

Each session is identified by a unique session ID from Claude Code. If sessions are merging incorrectly, check that each claude process is started fresh (not reusing an existing session ID).

Resources

VS Code Marketplace

Demo Video

GitHub Repository

CraftMyGame — the project that inspired Agent Flow

License: Apache 2.0