> For AI agents: the complete documentation index is available at https://flow.jig.md/llms.txt, the full documentation bundle is available at https://flow.jig.md/llms-full.txt.

# Build on reusable know-how

FLOW is the independent standard for packaging and invoking reusable methods.
A **Flow** puts code, Agent judgment, or both behind one method boundary.
A compatible host supplies local powers.

<div className="reader-grid">
<a className="reader-card" href="/guide/start"><span className="tile-index">AUTHOR A METHOD</span><h3>Build your first Flow.</h3><p>Choose a language and a compatible host. Understand the package and handler boundary.</p><span className="card-link">Start building ↗</span></a>
<a className="reader-card" href="/guide/"><span className="tile-index">IMPLEMENT THE STANDARD</span><h3>Find the exact contract.</h3><p>Work from the public package, values, protocol, SDK, and interoperability specifications.</p><span className="card-link">Open the specification map ↗</span></a>
<a className="reader-card" href="/guide/understand"><span className="tile-index">UNDERSTAND THE DESIGN</span><h3>Keep the boundary small.</h3><p>See why implementation freedom and locally supplied authority matter to reuse.</p><span className="card-link">Why FLOW exists ↗</span></a>
<a className="reader-card" href="/guide/for-agents"><span className="tile-index">FOR AGENTS</span><h3>Read the source of truth.</h3><p>Fetch focused Markdown or the full public bundle, without adopting host-specific assumptions.</p><span className="card-link">Get the context ↗</span></a>
</div>

## Find your task

| I want to…                                              | Read                                                                                                                    |
| ------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------- |
| See code and Agent work compose through one boundary    | [Understand FLOW](https://flow.jig.md/guide/understand.md), then [the Jig example](https://jig.md/guide/request-triage) |
| Package a reusable procedure                            | [Start building](https://flow.jig.md/guide/start.md), then [Package/1](https://flow.jig.md/spec/package-format.md)      |
| Write a Python method and exercise the protocol         | [Python SDK guide](https://flow.jig.md/guide/python.md)                                                                 |
| Write TypeScript under a qualified Jig build            | [Jig's first Flow](https://jig.md/guide/)                                                                               |
| Understand portable input and output values             | [JSON/1](https://flow.jig.md/spec/json-values.md)                                                                       |
| Validate inputs, settings, or results                   | [Schema/1](https://flow.jig.md/spec/schema-files.md)                                                                    |
| Launch a method or implement a host                     | [Run/1](https://flow.jig.md/spec/run-protocol.md)                                                                       |
| Implement or use an SDK                                 | [Run SDK/1](https://flow.jig.md/spec/run-sdk.md)                                                                        |
| Define an independently maintained capability interface | [Capability Contract/1](https://flow.jig.md/spec/capability-contracts.md)                                               |
| Define exact live-message meaning                       | [Channel Contract/1](https://flow.jig.md/spec/channel-contracts.md)                                                     |
| Resolve terminology or a common question                | [Concepts and questions](https://flow.jig.md/guide/concepts.md)                                                         |

## What belongs to a host?

Providers, credentials, permission, containment, and local execution support
are host decisions. FLOW does not make those choices for the consumer.
[Jig](https://jig.md/) documents one host; a host's supported languages are
separate from the languages with FLOW SDKs.

## How to read this documentation

The sidebar keeps authoring, explanation, and exact reference visible from every
page. Use search for a field or concept, and the outline to jump within a long
specification. Copy Markdown when you need the page in an Agent's context.

The standard is prerelease. An SDK candidate in source is not necessarily a
published package. Authoring guides identify their execution prerequisites;
implementers should qualify a concrete revision against the public
[conformance material](https://github.com/jiggy/jig/tree/main/conformance/run-1).