The Veyyon handbook

Veyyon runs in your terminal and edits real code. Bring your own model keys; the harness is tuned for coding work, not chat theater.

This handbook is for everyone who uses Veyyon or wants to understand it.

• Why Veyyon: value, design map, and benefits you should feel first.
• Install and first session: install, providers, quickstart, configuration.
• Everyday features: editing, sandbox, models, sessions, themes.
• Power features: plan mode, goals, branching, MCP, plugins, memory, profiles.
• How it works: deeper engineering account for contributors.

If you read nothing else: What Veyyon gives you, Getting started, Editing and repair, Models and providers.

What Veyyon is, in one paragraph

Veyyon is a fork of oh-my-pi: TypeScript and Bun for the CLI, TUI, tools, providers, and session loop; Rust natives for grep, PTY, and hashline edits. Install with bun install -g @veyyon/pi-coding-agent or bun dev from source. The command is veyyon (short alias vey). Config and state default to ~/.veyyon.

Shipped today: hashline edits, mnemopi memory, model roles, session trees, MCP, skills, and plan/goal modes.

Why it is different (shipped vs planned)

• Edits that land. Hashline and model-tuned edit tools with native verification; fewer retry loops on bad diffs.
• Explicit model slots. Pick the model you talk to, the model for subagents, and the model for compaction — three plain choices, no default-chain indirection.
• Honest interface. Veyyon Dark uses the silver palette; plan/goal modes and tool approval tiers are engine features.

Spec — not shipped: the full schema-based tool-call repair cascade, a unified single-write-path proof, and self-contained profiles. See What makes Veyyon different.

On honesty

This book states plainly what is built and what is planned. Pages marked Spec — not shipped describe target design not yet in the product. Credits: Acknowledgements.