Files and multimodal input

Managed Channels can hydrate provider attachments into message.contentParts. The SDK carries text, images, audio, video, and PDF documents in one provider-neutral prompt shape.

Pass attachments to the agent#

Managed conversation history does not contain the current inbound turn. runAgent() automatically chooses the inbound text or attachment parts when prompt is omitted. Build a combined prompt when the same turn can contain both message.text and message.contentParts:

channel.onMessage(async ({ thread, message }) => {
  const prompt = message.contentParts?.length
    ? [
        ...(message.text
          ? [{ type: "text" as const, text: message.text }]
          : []),
        ...message.contentParts,
      ]
    : message.text;

  await thread.runAgent({ prompt });
});

If you pass only message.text, the model will not receive hydrated binary attachments. If contentParts exists, do not append it to managed history yourself; runAgent adds the explicit prompt for this turn.

Understand the content mapping#

The binary value is base64. Whether the agent actually understands a media part depends on its selected model and framework. Choose a multimodal model and test the exact media types you accept.

File retrieval is best-effort. A provider-ingest failure can omit the attachment before the SDK receives a file handle. If Intelligence delivers a handle but the SDK cannot hydrate it, the SDK inserts a short failure note instead of failing the whole turn.

Slack file access#

Intelligence downloads files using the managed Slack bot token. The app must be in the conversation and have permission to read the file. Slack documents files:read as the scope that allows an app to download files from conversations it can access.

The current Intelligence-generated manifest requests both files:read and files:write. If the app predates that manifest:

1. Open the Channel in Intelligence, return to its Slack setup instructions, and apply the generated manifest so both bot token scopes are present. See Configure the Channel in Intelligence.
2. Reinstall the app so the workspace grants the scopes.
3. Copy the current Bot User OAuth token into Intelligence if Slack reissued it.
4. Invite the app to the source conversation.
5. Send a new file and verify the model receives it.

If attachments are omitted or arrive as retrieval-failure notes:

1. Confirm the reinstalled bot token includes files:read.
2. Confirm the app is a member of the source conversation.
3. Send a new file and inspect the real agent turn.

Teams file access#

Post a file#

thread.postFile() takes bytes and returns a result instead of throwing for an unsupported provider capability:

const csv = new TextEncoder().encode(
  ["id,status", "INC-421,investigating"].join("\n"),
);

const result = await thread.postFile({
  bytes: csv,
  filename: "incident-report.csv",
  title: "Incident report",
  altText: "CSV export of the incident report",
});

if (!result.ok) {
  await thread.post(`The report could not be attached: ${result.error}`);
}

On managed Channels, result.ok means Intelligence stored the managed asset, the provider acknowledged the file or image effect, and the SDK recorded the asset in canonical Thread history.

Managed Slack uses Slack's external-upload flow and can send general file types. The generated manifest includes the files:write bot scope. Apply the current manifest and reinstall if the Slack app predates it. Check result.ok, then verify the real Slack message when provider-side display matters.

Treat attachments as untrusted input#

• Validate declared MIME type and file signature before application-side processing.
• Put limits on decompression, parsing, page count, and extracted text.
• Do not execute macros or uploaded code.
• Resolve the provider user to an authenticated application identity before a file can trigger a consequential write.
• Avoid logging base64 content, signed download URLs, or document text.

See the IncomingMessage reference and AgentContentPart reference for the exact public shapes.