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Chat summary

Add a summary command that replaces explicit input with a conversation summary.

chatSummary() adds a conversation summary command. It looks for an explicit command in the latest user input, generates a summary, replaces the command with summary text, and exposes the generated summary as output metadata.

Installation

Import the Capability factory from -hub/agent/capabilities and add it to defineAgent({ capabilities }). Use the configuration example below as the starting point, then tighten modes, policies, stores, and providers for the Agent boundary.

What it adds

The Capability contributes input behavior similar to inputCommands(). By default it recognizes a summary command, summarizes the current conversation, and writes the summary into Agent Run Input context.

Configuration

Attach chatSummary() with chat() when users should request a summary from a chat surface. The default command uses the standard input command trigger.

server/agents/support.ts

import { defineAgent } from '@vite-hub/agent'
import { chat, chatSummary } from '@vite-hub/agent/capabilities'

export default defineAgent({
  driver: { model },
  capabilities: [
    chat(),
    chatSummary(),
  ],
})

Runtime behavior

chatSummary() runs during the input phase. When the configured command is present, it removes the command text, summarizes the source messages with a model, custom executor, or heuristic fallback, then replaces the command with Conversation summary.

The generated value is available as chatSummary in input context and as a finish extension for the invocation that generated it.

Requirements

The command name must be a valid Input Command name. Model-based summaries require an explicit model option; otherwise the Capability uses its heuristic fallback.

Disable the command only when another product surface invokes the summary behavior directly.

Driver support

Agent Driver	Support
Model-backed	Receives the transformed input containing the generated summary.
Harness-backed	Receives the transformed input before harness execution.
Custom-run-backed	Receives the transformed input and context values before `driver.run`.

Inspect and verify

Run a chat invocation with the summary command. Inspect the final Agent Run Input and confirm the command was replaced with Conversation summary text.

Inspect the finish extension and verify it appears only on the invocation that generated the summary.

Options

Option	Type	Default	Description
`command`	`false \| ChatSummaryCommandOptions`	`{ name: "summary", trigger: "/" }`	Enables or configures the summary Input Command.
`command.name`	`string`	`"summary"`	Command name.
`command.trigger`	`string`	`"/"`	Command prefix.
`command.description`	`string`	generated	Command description.
`execute`	`(input) => string \| { summary?: string }`	none	Custom summary generator.
`fallback`	`string`	`"No conversation to summarize."`	Summary used when generation returns no usable text.
`id`	`string`	`"chat-summary"`	Capability id and summary context key prefix.
`instructions`	`string`	generated	System instructions for model-backed summaries.
`maxLength`	`number`	`1200`	Maximum summary length.
`model`	AI SDK model	heuristic fallback	Model used for summaries.

Reference

chat()
inputCommands()
Source: packages/agent/src/capabilities/chat-summary.ts