Context Module

Pure function context builder for AI message preparation. Production context builder used by orchestration layer.

Exports

import { buildContext } from '@shared/context'
import type { AttachmentResolver, ContextBuilderOptions } from '@shared/context'

Core API

buildContext()

Production context builder - Pure function that prepares messages for AI generation.

Used directly by orchestration.ts and wrapped by genMessageContext() in the session module.

async function buildContext(
  messages: Message[],
  options: ContextBuilderOptions
): Promise<Message[]>

Processing pipeline:

1. Filter incomplete messages (generating: true)
2. Apply compaction (from latest compaction point)
3. Apply message count limit
4. Inject attachment content via AttachmentResolver

Usage pattern:

import { buildContext, createAttachmentResolver } from '@shared/context'

const resolver = createAttachmentResolver()
const contextMessages = await buildContext(messages, {
  attachmentResolver: resolver,
  maxContextMessageCount: 50,
})

AttachmentResolver

Platform abstraction for reading attachments. Implemented by renderer.

interface AttachmentResolver {
  read(id: string): Promise<string | null>
}

ContextBuilderOptions

interface ContextBuilderOptions {
  attachmentResolver: AttachmentResolver
  maxContextMessageCount?: number
  compactionPoints?: CompactionPoint[]
  keepToolCallRounds?: number
  modelSupportToolUseForFile?: boolean
}

Options:

• attachmentResolver - Required. Platform abstraction for accessing attachments
• maxContextMessageCount - Optional. Limits context to the most recent N messages
• compactionPoints - Optional. History compression points for context optimization
• keepToolCallRounds - Optional. Number of recent tool call rounds to preserve (default: 2)
• modelSupportToolUseForFile - Optional. Whether model supports tool use for file reading (default: false)

Architecture

• Single source of truth - buildContext() is the only context builder in production
• Zero renderer dependencies - Pure shared module
• Immutable - Never mutates input messages
• Dependency injection - AttachmentResolver provided by caller
• Thin wrapper pattern - genMessageContext() in session module wraps buildContext() with session-specific logic