Function manageContext

src/core/context-management/index.ts:291–427

({
	messages,
	totalTokens,
	contextWindow,
	maxTokens,
	apiHandler,
	autoCondenseContext,
	autoCondenseContextPercent,
	systemPrompt,
	taskId,
	customCondensingPrompt,
	profileThresholds,
	currentProfileId,
	metadata,
	environmentDetails,
	filesReadByRoo,
	cwd,
	rooIgnoreController,
	useAvailableInputForContextPercent,
}: ContextManagementOptions)

 * @returns {Promise<ApiMessage[]>} The original, condensed, or truncated conversation messages.
 */
export async function manageContext({
	messages,
	totalTokens,
	contextWindow,
	maxTokens,
	apiHandler,
	autoCondenseContext,
	autoCondenseContextPercent,
	systemPrompt,
	taskId,
	customCondensingPrompt,
	profileThresholds,
	currentProfileId,
	metadata,
	environmentDetails,
	filesReadByRoo,
	cwd,
	rooIgnoreController,
	useAvailableInputForContextPercent,
}: ContextManagementOptions): Promise<ContextManagementResult> {
	let error: string | undefined
	let errorDetails: string | undefined
	let cost = 0
	// Calculate the maximum tokens reserved for response
	// vscode-lm reports maxTokens: -1 (unlimited); a negative reserve must not distort the window math.
	const reservedTokens = maxTokens && maxTokens > 0 ? maxTokens : ANTHROPIC_DEFAULT_MAX_TOKENS

	// Estimate tokens for the last message (which is always a user message)
	const lastMessage = messages[messages.length - 1]
	const lastMessageContent = lastMessage.content
	const lastMessageTokens = Array.isArray(lastMessageContent)
		? await estimateTokenCount(lastMessageContent, apiHandler)
		: await estimateTokenCount([{ type: "text", text: lastMessageContent as string }], apiHandler)

	// Calculate total effective tokens (totalTokens never includes the last message)
	const prevContextTokens = totalTokens + lastMessageTokens

	// Calculate available tokens for conversation history
	// Truncate if we're within TOKEN_BUFFER_PERCENTAGE of the context window
	const allowedTokens = contextWindow * (1 - TOKEN_BUFFER_PERCENTAGE) - reservedTokens

	// Determine the effective threshold to use
	let effectiveThreshold = autoCondenseContextPercent
	const profileThreshold = profileThresholds[currentProfileId]
	if (profileThreshold !== undefined) {
		if (profileThreshold === -1) {
			// Special case: -1 means inherit from global setting
			effectiveThreshold = autoCondenseContextPercent
		} else if (profileThreshold >= MIN_CONDENSE_THRESHOLD && profileThreshold <= MAX_CONDENSE_THRESHOLD) {
			// Valid custom threshold
			effectiveThreshold = profileThreshold
		} else {
			// Invalid threshold value, fall back to global setting
			console.warn(
				`Invalid profile threshold ${profileThreshold} for profile "${currentProfileId}". Using global default of ${autoCondenseContextPercent}%`,
			)
			effectiveThreshold = autoCondenseContextPercent
		}