Hooks

Composer state

Hook	Returns
`useComposerBusyState()`	Whether the composer is busy. Requires `ComposerBusyProvider`. Type: `ComposerBusyState`.
`useComposerPauseView()`	`{ kind: "mcp" \| "ask-user" \| "compose" }` — why input is paused. Types: `ComposerPauseView`, `ThreadPauseState`.

threadHasPendingMcpAuth(state) is the standalone predicate behind the "mcp" case.

Server capabilities

import { useServerCapabilities } from "@truefoundry/trueforge-ui";

const capabilities = useServerCapabilities();
// { sandbox: { enabled }, skill: { enabled, reason? }, settings?: { enabled } } | null

Returns the resolved value from your server’s getCapabilities(), or null while it is still loading or if the call failed. Use it to gate your own chrome the same way the SDK gates its sandbox, skill, and settings affordances. See Server contract.

MCP auth

const auth = useMCPAuth({ callbackPath: "/mcp-callback" });

MCP_AUTH_POPUP_CHANNEL is "truefoundry-mcp-auth-popup" — the BroadcastChannel name used to signal completion back to the opener. Types: McpAuthCallback, McpAuthPopupMessage, UseMCPAuthOptions. See MCP OAuth.

assistant-ui state

useAui, useAuiState, and the AssistantState type come from @assistant-ui/react, which the SDK bundles as a dependency and also declares as an optional peer. They are re-exported from the package root and from a dedicated subpath:

import { useAui, useAuiState } from "@truefoundry/trueforge-ui/assistant-ui";

Runtime hooks

Import these from @truefoundry/trueforge-ui like everything else:

Export	Purpose
`useTrueForgeAgentRuntime`	The underlying runtime hook.
`useTrueForgeAgentSpec`	Read the active agent spec.
`useTrueForgeUpdateAgentSpec`	Mutate the draft spec.
`useTrueForgeCancel`	Cancel the in-flight turn.
`useTrueForgeTurnId`	The id of the current turn.
`useTrueForgeHistoryPagination`	Page backwards through history.
`useTrueForgeMcpAuth`	Low-level MCP auth state.
`useTrueForgeRespondToToolApproval`	Approve or reject a tool call.
`useTrueForgeToolResponses`	Read tool responses.
`useTrueForgeDownloadSandboxFile`	Download a sandbox artifact.
`mergeAgentSpec`	Merge partial specs.
`trueForgeAttachmentAdapter`	Default attachment adapter.

Types: DraftAgentConfig, NamedAgentConfig, TrueForgeAgentConfig, UseTrueForgeAgentRuntimeOptions.

Utilities

computeAgentStepsSplit(parts: AgentStepPart[], isRunning: boolean): AgentStepsSplitResult;

Splits message parts into the steps shown inline versus those collapsed into the steps card. Both AgentStepPart and AgentStepsSplitResult are exported.

Getting Started

TrueForge Harness

SDK

UI Chat

Project

Composer state

Server capabilities

MCP auth

assistant-ui state

Runtime hooks

Utilities

​Composer state

​Server capabilities

​MCP auth

​assistant-ui state

​Runtime hooks

​Utilities

Composer state

Server capabilities

MCP auth

assistant-ui state

Runtime hooks

Utilities