fleet-memory/hindsight-docs/docs-integrations/chat.md

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5	Vercel Chat SDK Persistent Memory with Hindsight | Integration	Give your Vercel Chat SDK bot persistent, per-user memory across Slack, Discord, Teams, and more. Single handler wrapper, no custom plumbing required.

Vercel Chat SDK

We built @vectorize-io/hindsight-chat to give Vercel Chat SDK bots persistent, per-user memory with a single handler wrapper. The integration works across Slack, Discord, Teams, Google Chat, GitHub, and Linear — no custom plumbing required.

View Changelog →

Installation

npm install @vectorize-io/hindsight-chat

Quick Start

import { Chat } from 'chat';
import { HindsightClient } from '@vectorize-io/hindsight-client';
import { withHindsightChat } from '@vectorize-io/hindsight-chat';
import { streamText } from 'ai';
import { openai } from '@ai-sdk/openai';

const chat = new Chat({ connectors: [/* your connectors */] });
const hindsight = new HindsightClient({ apiKey: process.env.HINDSIGHT_API_KEY });

chat.onNewMention(
  withHindsightChat(
    {
      client: hindsight,
      bankId: (msg) => msg.author.userId, // per-user memory
    },
    async (thread, message, ctx) => {
      await thread.subscribe();

      const result = await streamText({
        model: openai('gpt-4o'),
        system: ctx.memoriesAsSystemPrompt(),
        messages: [{ role: 'user', content: message.text }],
      });

      // Stream the response
      const chunks: string[] = [];
      for await (const chunk of result.textStream) {
        chunks.push(chunk);
      }
      const fullResponse = chunks.join('');
      await thread.post(fullResponse);

      // Store the conversation in memory
      await ctx.retain(
        `User: ${message.text}\nAssistant: ${fullResponse}`
      );
    }
  )
);

Configuration

withHindsightChat(options, handler)

withHindsightChat wraps your existing Chat SDK handler and injects memory context automatically. It returns a standard handler (thread, message) => Promise<void> so it drops in without changing your handler signature.

Options

Option	Type	Default	Description
client	HindsightClient	required	Hindsight client instance
bankId	string | (msg) => string	required	Memory bank ID or resolver function
recall.enabled	boolean	true	Auto-recall memories before handler
recall.budget	'low' | 'mid' | 'high'	'mid'	Processing budget for recall
recall.maxTokens	number	API default	Max tokens for recall results
recall.types	FactType[]	all	Filter to specific fact types
recall.includeEntities	boolean	true	Include entity observations
retain.enabled	boolean	false	Auto-retain inbound messages
retain.async	boolean	true	Fire-and-forget retain
retain.tags	string[]	–	Tags for retained memories
retain.metadata	Record<string, string>	–	Metadata for retained memories

Context (ctx)

We inject a third ctx argument into your handler that exposes the full Hindsight memory API scoped to the current user's bank:

Property/Method	Description
ctx.bankId	Resolved bank ID
ctx.memories	Array of recalled memories
ctx.entities	Entity observations (or null)
ctx.memoriesAsSystemPrompt(options?)	Format memories for LLM system prompt
ctx.retain(content, options?)	Store content in memory
ctx.recall(query, options?)	Search memories
ctx.reflect(query, options?)	Reason over memories

Examples

Subscribed Message Handler

chat.onSubscribedMessage(
  withHindsightChat(
    {
      client: hindsight,
      bankId: (msg) => msg.author.userId,
      recall: { budget: 'high', maxTokens: 1000 },
    },
    async (thread, message, ctx) => {
      const result = await generateText({
        model: openai('gpt-4o'),
        system: ctx.memoriesAsSystemPrompt(),
        messages: [{ role: 'user', content: message.text }],
      });
      await thread.post(result.text);
    }
  )
);

Auto-Retain Inbound Messages

chat.onNewMention(
  withHindsightChat(
    {
      client: hindsight,
      bankId: (msg) => msg.author.userId,
      retain: { enabled: true, tags: ['slack', 'inbound'] },
    },
    async (thread, message, ctx) => {
      // Inbound message is already being retained automatically
      const result = await generateText({
        model: openai('gpt-4o'),
        system: ctx.memoriesAsSystemPrompt(),
        messages: [{ role: 'user', content: message.text }],
      });
      await thread.post(result.text);

      // Retain the assistant response separately
      await ctx.retain(`Assistant: ${result.text}`, {
        tags: ['slack', 'outbound'],
      });
    }
  )
);

Static Bank ID (Shared Memory)

// All users share the same memory bank
chat.onNewMention(
  withHindsightChat(
    { client: hindsight, bankId: 'shared-team-memory' },
    async (thread, message, ctx) => {
      // ...
    }
  )
);

Error Handling

We designed the integration so that memory failures never break your bot. Auto-recall and auto-retain errors are caught internally, logged as warnings, and the handler continues with empty memories. Manual ctx.retain(), ctx.recall(), and ctx.reflect() calls propagate errors normally so you can handle them as needed.