@chat-adapter/shared

npm package: @chat-adapter/shared

Shared utilities for Chat SDK adapters. Provides common helpers used across adapter implementations.

Documentation: chat-sdk.dev/docs/contributing/building · Guides: vercel.com/kb/chat-sdk

Installation

pnpm add @chat-adapter/shared

Utilities

Adapter helpers

• extractCard(message) - extract a CardElement from an AdapterPostableMessage
• extractFiles(message) - extract FileUpload[] from an AdapterPostableMessage
• extractPostableAttachments(message) - extract Attachment[] from an AdapterPostableMessage

Buffer conversion

• toBuffer(input) - convert various inputs (Buffer, Blob, string, URL) to Buffer
• toBufferSync(input) - synchronous version of toBuffer
• bufferToDataUri(buffer, mimeType) - convert a Buffer to a data URI string

Card conversion

• cardToFallbackText(card) - render a CardElement as plain text for platforms that don't support cards
• createEmojiConverter(platform) - create a function that converts emoji placeholders to platform format
• mapButtonStyle(style) - map generic button styles to platform-specific variants
• renderGfmTable(headers, rows) - render a GitHub Flavored Markdown table
• escapeTableCell(text) - escape pipe characters in table cells

Token encryption

AES-256-GCM helpers for encrypting OAuth tokens at rest before writing them to a state adapter. Used by @chat-adapter/slack and @chat-adapter/linear; available to any adapter that persists credentials.

• encryptToken(plaintext, key) - encrypt a string and return an EncryptedTokenData envelope (random 12-byte IV per call)
• decryptToken(data, key) - decrypt an envelope back to the original string
• decodeKey(encoded) - decode a hex-64 or base64-44 encoded 32-byte key; throws on wrong length
• isEncryptedTokenData(value) - type guard for distinguishing envelopes from legacy plaintext records
• EncryptedTokenData - the envelope type ({ data, iv, tag }, all base64)

Error classes

Standardized errors for adapter implementations:

• AdapterError - base error class
• AdapterRateLimitError - platform rate limit (includes retryAfter)
• AuthenticationError - expired or invalid tokens
• NetworkError - connection failures
• PermissionError - missing scopes or permissions
• ResourceNotFoundError - missing channel/thread/message
• ValidationError - invalid config or input

AI Coding Agents

If you use an AI coding agent such as OpenAI Codex, Claude Code, or Cursor, install the Chat SDK skill so it knows the SDK APIs, adapter patterns, and project conventions before writing code.

npx skills add vercel/chat

The skill references bundled documentation in node_modules/chat/docs, plus adapter guides and starter templates in the published package.

You can also install the Vercel Plugin for a broader agent toolkit — it includes the Chat SDK skill alongside specialist agents, agent slash commands, and more:

npx plugins add vercel/vercel-plugin

The plugin is optional; the skill alone is enough to build with Chat SDK.

For agent-readable documentation, see chat-sdk.dev/llms.txt (page index) or chat-sdk.dev/llms-full.txt (full text).

License

MIT