Grouping SDK exports into submodules

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:

// 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:

# Before
from iii import IIIInvocationError, ChannelReader, FunctionRef
# After
from iii.errors import InvocationError
from iii.channel import ChannelReader
from iii.runtime import FunctionRef

Rust:

// 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.

​What changed

​Errors renamed

​Submodule contents

​Migration

​Why

What changed

Errors renamed

Submodule contents

Migration

Why