# ComposerRuntime URL: /docs/api-reference/runtimes/composer-runtime ComposerRuntime state and actions for controlling assistant-ui composer text, attachments, submission, cancellation, and pending input. > For AI agents: a documentation index is available at [llms.txt](/llms.txt). Use `.md` for canonical markdown pages; `.mdx` is kept as a backwards-compatible alias on supported URL paths. ## API Reference ### ComposerRuntime - `path`: `ComposerRuntimePath` - `ref`: `string` - `threadSelector`: `ComposerRuntimePath["threadSelector"]` - `type`: `"main"` - `composerSource`: `"thread"` - `type`: `"edit" | "thread"` - `getState`: `() => ComposerState` — Get the current state of the composer. Includes any data that has been added to the composer. - `addAttachment`: `(fileOrAttachment: File | CreateAttachment) => Promise` — Add an attachment to the composer. Accepts either a standard File object (processed through the AttachmentAdapter) or a CreateAttachment descriptor for external-source attachments (URLs, API data, CMS references). External descriptors bypass the adapter's \`add()\` step but still respect \`adapter.accept\` when an adapter is configured; without an adapter they are added as-is. - `setText`: `(text: string) => void` — Set the text of the composer. - `setRole`: `(role: MessageRole) => void` — Set the role of the composer. For instance, if you'd like a specific message to have the 'assistant' role, you can do so here. - `setRunConfig`: `(runConfig: RunConfig) => void` — Set the run config of the composer. This is used to send custom configuration data to the model. Within your backend, you can use the \`runConfig\` object. Example: \`\`\`ts composerRuntime.setRunConfig({ custom: { customField: "customValue" } }); \`\`\` - `reset`: `() => Promise` — Reset the composer. This will clear the entire state of the composer, including all text and attachments. - `clearAttachments`: `() => Promise` — Clear all attachments from the composer. - `send`: `(options?: SendOptions) => void` — Send a message. This will send whatever text or attachments are in the composer. - `cancel`: `() => void` — Cancel the current run. In edit mode, this will exit edit mode. - `steerQueueItem`: `(queueItemId: string) => void` — Promote a queued message so it processes next. - `removeQueueItem`: `(queueItemId: string) => void` — Remove a queued message. - `subscribe`: `(callback: () => void) => Unsubscribe` — Listens for changes to the composer state. - `getAttachmentByIndex`: `(idx: number) => AttachmentRuntime` — Get an attachment by index. - `startDictation`: `() => void` — Start dictation to convert voice to text input. Requires a DictationAdapter to be configured. - `stopDictation`: `() => void` — Stop the current dictation session. - `setQuote`: `(quote: QuoteInfo | undefined) => void` — Set a quote for the next message. Pass undefined to clear. - `unstable_on`: `(event: E, callback: ComposerRuntimeEventCallback) => Unsubscribe` (deprecated: This API is still under active development and might change without notice.) ### ComposerState - `canCancel`: `boolean` - `canSend`: `boolean` - `isEditing`: `boolean` - `isEmpty`: `boolean` - `text`: `string` - `role`: `MessageRole` - `attachments`: `readonly Attachment[]` - `runConfig`: `RunConfig` - `custom?`: `Record` - `attachmentAccept`: `string` - `dictation?`: `DictationState` — The current state of dictation. Undefined when dictation is not active. - `status`: `DictationAdapter.Status` - `type`: `"starting" | "running"` - `transcript?`: `string` - `inputDisabled?`: `boolean` - `quote?`: `QuoteInfo` — The currently quoted text, if any. Undefined when no quote is set. - `text`: `string` - `messageId`: `string` - `queue`: `readonly QueueItemState[]` — Messages waiting to be processed. Empty unless the \`queue\` capability is set. - `type`: `"thread"` ### EditComposerRuntime - `path`: `ComposerRuntimePath` - `ref`: `string` - `threadSelector`: `EditComposerRuntime["path"]["threadSelector"]` - `type`: `"main"` - `messageSelector`: `EditComposerRuntime["path"]["messageSelector"]` - `type`: `"messageId"` - `composerSource`: `"edit"` - `type`: `"edit" | "thread"` - `addAttachment`: `(fileOrAttachment: File | CreateAttachment) => Promise` — Add an attachment to the composer. Accepts either a standard File object (processed through the AttachmentAdapter) or a CreateAttachment descriptor for external-source attachments (URLs, API data, CMS references). External descriptors bypass the adapter's \`add()\` step but still respect \`adapter.accept\` when an adapter is configured; without an adapter they are added as-is. - `setText`: `(text: string) => void` — Set the text of the composer. - `setRole`: `(role: MessageRole) => void` — Set the role of the composer. For instance, if you'd like a specific message to have the 'assistant' role, you can do so here. - `setRunConfig`: `(runConfig: RunConfig) => void` — Set the run config of the composer. This is used to send custom configuration data to the model. Within your backend, you can use the \`runConfig\` object. Example: \`\`\`ts composerRuntime.setRunConfig({ custom: { customField: "customValue" } }); \`\`\` - `reset`: `() => Promise` — Reset the composer. This will clear the entire state of the composer, including all text and attachments. - `clearAttachments`: `() => Promise` — Clear all attachments from the composer. - `send`: `(options?: SendOptions) => void` — Send a message. This will send whatever text or attachments are in the composer. - `cancel`: `() => void` — Cancel the current run. In edit mode, this will exit edit mode. - `steerQueueItem`: `(queueItemId: string) => void` — Promote a queued message so it processes next. - `removeQueueItem`: `(queueItemId: string) => void` — Remove a queued message. - `subscribe`: `(callback: () => void) => Unsubscribe` — Listens for changes to the composer state. - `startDictation`: `() => void` — Start dictation to convert voice to text input. Requires a DictationAdapter to be configured. - `stopDictation`: `() => void` — Stop the current dictation session. - `setQuote`: `(quote: QuoteInfo | undefined) => void` — Set a quote for the next message. Pass undefined to clear. - `unstable_on`: `(event: E, callback: ComposerRuntimeEventCallback) => Unsubscribe` (deprecated: This API is still under active development and might change without notice.) - `getState`: `() => EditComposerState` - `beginEdit`: `() => void` - `getAttachmentByIndex`: `(idx: number) => AttachmentRuntime & { source: "edit-composer"; }` ### EditComposerState - `canCancel`: `boolean` - `canSend`: `boolean` - `isEditing`: `boolean` - `isEmpty`: `boolean` - `text`: `string` - `role`: `MessageRole` - `attachments`: `readonly Attachment[]` - `runConfig`: `RunConfig` - `custom?`: `Record` - `attachmentAccept`: `string` - `dictation?`: `DictationState` — The current state of dictation. Undefined when dictation is not active. - `status`: `DictationAdapter.Status` - `type`: `"starting" | "running"` - `transcript?`: `string` - `inputDisabled?`: `boolean` - `quote?`: `QuoteInfo` — The currently quoted text, if any. Undefined when no quote is set. - `text`: `string` - `messageId`: `string` - `queue`: `readonly QueueItemState[]` — Messages waiting to be processed. Empty unless the \`queue\` capability is set. - `type`: `"edit"` - `parentId`: `string | null` - `sourceId`: `string | null`