Using Trajectories Sdk

Using the Trajectories SDK

Overview

The agent-trajectories SDK provides two APIs for programmatically capturing agent work trajectories: TrajectoryClient (persistent, async) and TrajectoryBuilder (in-memory, sync).

When to Use

• Building tools or agents that need to record their work programmatically
• Integrating trajectory capture into CI/CD or automation pipelines
• Creating trajectories from code rather than CLI
• Not for: Manual CLI usage (use trail CLI instead)

Quick Reference

Installation

npm install agent-trajectories

TrajectoryClient (Persistent Storage)

Use when you need trajectories saved to .trajectories/ on disk.

import { TrajectoryClient } from 'agent-trajectories/sdk';

const client = new TrajectoryClient({ defaultAgent: 'my-agent' });
await client.init(); // Required before use

// Start a trajectory
const session = await client.start('Implement feature X');

// Record work in chapters
await session.chapter('Research');
await session.note('Found existing auth patterns');
await session.finding('Current implementation uses JWT');

await session.chapter('Implementation');
await session.decide(
  'JWT vs Session tokens',
  'JWT',
  'Better for stateless API clients',
  [{ option: 'Session tokens', reason: 'Simpler but requires server state' }]
);

// Complete with retrospective
await session.done('Implemented JWT auth', 0.9, {
  approach: 'Extended existing auth module',
  learnings: ['JWT refresh flow needs careful error handling'],
});

await client.close();

Client Options

new TrajectoryClient({
  dataDir: '.trajectories',    // Storage location (default)
  defaultAgent: 'agent-name',  // Default agent for chapters
  autoSave: true,              // Auto-persist after each operation (default)
});

Key Client Methods

Session Methods

TrajectoryBuilder (In-Memory)

Use when you don't need persistence - just building a trajectory data structure.

import { TrajectoryBuilder, trajectory } from 'agent-trajectories/sdk';

// Shorthand
const result = trajectory('Fix auth bug')
  .chapter('Investigation', 'claude')
  .finding('Null pointer in login handler')
  .decide('Fix approach', 'Add null check', 'Simplest correct fix')
  .done('Fixed null pointer exception', 0.95);

// Export
console.log(TrajectoryBuilder.create('Task')
  .chapter('Work', 'agent')
  .note('Did the thing')
  .toMarkdown());

Builder is synchronous and chainable. Call .done(), .complete(), or .build() to get the Trajectory object.

Export Formats

Both Client sessions and Builder support:

session.toMarkdown();    // Human-readable markdown
session.toJSON();        // Raw JSON data
session.toJSON(true);    // Compact JSON
session.toTimeline();    // Chronological timeline view
session.toPRSummary();   // Optimized for PR descriptions

Common Mistakes