> ## Documentation Index
> Fetch the complete documentation index at: https://iii.dev/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Grouping SDK exports into submodules

> The invocation error types are renamed (InvocationError, Error) and the channel, trigger, and runtime types move to named submodules across the Node, Python, and Rust SDKs. The old root paths are removed in 0.20.0; code must move to the new submodule and name paths.

## What changed

The flat root export surface of the three SDKs is reorganized into named submodules. This slice covers four groups. The old root import paths are removed in 0.20.0, so upgrading requires moving these imports to their new paths.

| Group   | Node subpath      | Python submodule | Rust module        |
| ------- | ----------------- | ---------------- | ------------------ |
| errors  | `iii-sdk/errors`  | `iii.errors`     | `iii_sdk::errors`  |
| channel | `iii-sdk/channel` | `iii.channel`    | `iii_sdk::channel` |
| trigger | `iii-sdk/trigger` | `iii.trigger`    | `iii_sdk::trigger` |
| runtime | `iii-sdk/runtime` | `iii.runtime`    | `iii_sdk::runtime` |

## Errors renamed

The `III` prefix is dropped from the invocation error types.

| SDK    | Before                   | After                 | Canonical path           |
| ------ | ------------------------ | --------------------- | ------------------------ |
| Node   | `IIIInvocationError`     | `InvocationError`     | `iii-sdk/errors`         |
| Node   | `IIIInvocationErrorInit` | `InvocationErrorInit` | `iii-sdk/errors`         |
| Python | `IIIInvocationError`     | `InvocationError`     | `iii.errors`             |
| Rust   | `IIIError`               | `Error`               | `iii_sdk::errors::Error` |

Behavior is unchanged. In Node, the thrown error's `name` is now `InvocationError`. The old names are removed from the package root in 0.20.0; import the new names from their canonical paths.

## Submodule contents

| Group   | Symbols                                                                                                                          |
| ------- | -------------------------------------------------------------------------------------------------------------------------------- |
| channel | `ChannelReader`, `ChannelWriter`, `StreamChannelRef`, `Channel`                                                                  |
| trigger | `Trigger`, `TriggerConfig`, `TriggerHandler` (Rust also: `IIITrigger`)                                                           |
| runtime | `FunctionRef`, `TriggerTypeRef` (Rust also: `IIIConnectionState`, `WorkerMetadata`, `FunctionInfo`, `TriggerInfo`, `WorkerInfo`) |

The set per language matches each SDK's existing surface. Symbols absent from a language are not added in this slice; cross language parity is tracked separately.

## Migration

Update imports to the new paths. The old root paths are removed in 0.20.0, so this move is required.

Node:

```ts theme={"theme":{"light":"catppuccin-latte","dark":"dark-plus"}}
// Before
import { IIIInvocationError, ChannelReader, FunctionRef } from 'iii-sdk'
// After
import { InvocationError } from 'iii-sdk/errors'
import { ChannelReader } from 'iii-sdk/channel'
import type { FunctionRef } from 'iii-sdk/runtime'
```

Python:

```python theme={"theme":{"light":"catppuccin-latte","dark":"dark-plus"}}
# Before
from iii import IIIInvocationError, ChannelReader, FunctionRef
# After
from iii.errors import InvocationError
from iii.channel import ChannelReader
from iii.runtime import FunctionRef
```

Rust:

```rust theme={"theme":{"light":"catppuccin-latte","dark":"dark-plus"}}
// Before
use iii_sdk::{ChannelReader, FunctionRef, IIIError};
// After
use iii_sdk::channel::ChannelReader;
use iii_sdk::errors::Error;
use iii_sdk::runtime::FunctionRef;
```

## Why

The SDK root re-exported dozens of symbols flatly. Grouping them into `errors`, `channel`, `trigger`, and `runtime` submodules makes the surface navigable and prepares for extracting standalone libraries later. 0.20.0 is a clean break: the old root paths are removed rather than kept as aliases.