Method buildSessionSummaryMessages

pkg/session/session.go:1134–1166

buildSessionSummaryMessages builds system messages containing the session summary if one exists. Session summaries are context-specific per session and thus should not have a checkpoint (they will be cached alongside the first user message anyway) startIndex is the index in items from which convers

(items []Item)

// Otherwise it is lastSummaryIndex+1 (i.e. right after the summary item), or
// 0 when there is no summary.
func (s *Session) buildSessionSummaryMessages(items []Item) ([]chat.Message, int) {
	var messages []chat.Message
	// Find the last summary index to determine where conversation messages start
	// and to include the summary in session summary messages
	lastSummaryIndex := -1
	for i := range slices.Backward(items) {
		if items[i].Summary != "" {
			lastSummaryIndex = i
			break
		}
	}

	if lastSummaryIndex >= 0 && lastSummaryIndex < len(items) {
		messages = append(messages, chat.Message{
			Role:      chat.MessageRoleUser,
			Content:   "Session Summary: " + items[lastSummaryIndex].Summary,
			CreatedAt: s.now().Format(time.RFC3339),
		})
	}

	// Determine where conversation messages should start.
	// If the summary has a FirstKeptEntry, we start from there so that
	// messages kept during compaction are included after the summary.
	startIndex := lastSummaryIndex + 1
	if lastSummaryIndex >= 0 {
		kept := items[lastSummaryIndex].FirstKeptEntry
		if kept > 0 && kept < lastSummaryIndex {
			startIndex = kept
		}
	}

	return messages, startIndex
}

// CompactionInput returns the chat messages that the compactor should
// summarize together with their origin indices in s.Messages. The