Method structuredSummarize

cli/history_compactor.go:288–357

structuredSummarize summarizes the "middle" block of messages using a structured fact-extraction prompt.

(
	ctx context.Context,
	history []models.Message,
	llmClient client.LLMClient,
	cfg CompactConfig,
)

// structuredSummarize summarizes the "middle" block of messages using
// a structured fact-extraction prompt.
func (hc *HistoryCompactor) structuredSummarize(
	ctx context.Context,
	history []models.Message,
	llmClient client.LLMClient,
	cfg CompactConfig,
) ([]models.Message, error) {
	// Find boundaries: [system messages | middle (to summarize) | recent (keep verbatim)]
	systemEnd := 0
	for i, msg := range history {
		if msg.Role == "system" && i == systemEnd {
			systemEnd = i + 1
		} else {
			break
		}
	}

	recentStart := len(history) - cfg.MinKeepRecent
	if recentStart <= systemEnd {
		// Not enough messages to split — nothing to summarize
		return history, nil
	}

	middleMessages := history[systemEnd:recentStart]
	if len(middleMessages) < 4 {
		return history, nil
	}

	// Build input for the summarizer
	var sb strings.Builder
	for _, msg := range middleMessages {
		content := msg.Content
		if len(content) > 2000 {
			content = content[:1500] + "\n... [truncated for summarization] ...\n" + content[len(content)-300:]
		}
		sb.WriteString(fmt.Sprintf("[%s]: %s\n\n", msg.Role, content))
	}

	prompt := structuredSummaryPrompt + "\n\nCONVERSATION SEGMENT TO EXTRACT FROM:\n\n" + sb.String()

	summaryHistory := []models.Message{
		{Role: "user", Content: prompt},
	}

	// Derive from parent ctx so that a user-initiated cancel (Ctrl+C / ESC)
	// propagates and aborts the long summarization. We add our OWN generous
	// timeout (10 min) to protect against ambient turn-level deadlines that
	// might be shorter than the summary LLM call.
	summarizeCtx, cancel := context.WithTimeout(ctx, 10*time.Minute)
	defer cancel()

	response, err := llmClient.SendPrompt(summarizeCtx, prompt, summaryHistory, 0)
	if err != nil {
		return nil, fmt.Errorf("structured summarization LLM call failed: %w", err)
	}

	// Reconstruct: system + summary message + recent messages
	result := make([]models.Message, 0, systemEnd+1+cfg.MinKeepRecent)
	result = append(result, history[:systemEnd]...)