14-onboard-to-codebase

Onboard to Codebase

Agent reads a codebase and produces a structured architecture overview.

Prerequisites

• sandcaster CLI installed (from monorepo: cd apps/cli && bun link)

Setup

export E2B_API_KEY="your-key"       # https://e2b.dev/dashboard
export OPENAI_API_KEY="your-key"    # https://platform.openai.com/api-keys

Run

sandcaster "Explain the architecture of this codebase"

What Happens

The agent reads the project structure, entry points, key files, and dependencies, then produces a structured JSON report covering the tech stack, module map, entry points, data flow, and design patterns.

Configuration

See sandcaster.json for the full configuration. Key settings:

• model: gpt5 (OpenAI gpt-5.4 — cost-efficient default)
• maxTurns: 20 (enough for thorough codebase exploration)
• allowedTools: Read, Glob, Grep (read-only analysis)
• outputFormat: JSON schema for architecture report

Troubleshooting

• "No LLM provider API key found": Set OPENAI_API_KEY in your environment
• "E2B_API_KEY not set": Get a key at https://e2b.dev/dashboard
• Model not available: Replace gpt5 with sonnet or haiku in sandcaster.json