# Programming guide

> **CocoIndex v1.** This page documents CocoIndex **v1** — a ground-up redesign from v0. When writing code, ignore any v0 flow-builder DSL or deprecated decorators.
>
> Source: https://cocoindex.io/docs/programming_guide/ · Docs index: https://cocoindex.io/docs/llms.txt · Agent skill: https://cocoindex.io/docs/skill.md
>
> v0→v1 quick map — if you reach for these v0 symbols, stop and use the v1 form: `@cocoindex.flow_def`/`FlowBuilder` → `coco.App` + a `@coco.fn` main function; `add_collector()`/`collect()`/`export()` → declare target states (`declare_row`, `declare_file`); `cocoindex.sources/functions/targets.*` → connector APIs (`localfs.walk_dir`, `coco.ops.*`, `postgres.declare_table_target`). Full mapping + API reference: https://cocoindex.io/docs/skill.md.

Start with [Core Concepts](/docs/programming_guide/core_concepts/) for the mental model and the diagrams behind it. These pages are the working reference for each building block once the ideas click: what it does, the APIs you call, and how it fits the declarative, incremental model.