Function partsToMessageParts

coderd/x/chatd/chatprompt/chatprompt.go:1499–1632

partsToMessageParts converts SDK chat message parts into fantasy message parts for LLM dispatch. resolved is a lookup map for file bytes, and policy controls whether missing file-backed parts are dropped or replaced with text placeholders.

(
	ctx context.Context,
	logger slog.Logger,
	parts []codersdk.ChatMessagePart,
	resolved map[uuid.UUID]FileData,
	policy missingFilePolicy,
)

// bytes, and policy controls whether missing file-backed parts are
// dropped or replaced with text placeholders.
func partsToMessageParts(
	ctx context.Context,
	logger slog.Logger,
	parts []codersdk.ChatMessagePart,
	resolved map[uuid.UUID]FileData,
	policy missingFilePolicy,
) []fantasy.MessagePart {
	result := make([]fantasy.MessagePart, 0, len(parts))
	for _, part := range parts {
		switch part.Type {
		case codersdk.ChatMessagePartTypeText:
			// Anthropic rejects empty text content blocks with
			// "text content blocks must be non-empty". Empty parts
			// can arise when a stream sends TextStart/TextEnd with
			// no delta in between. We filter them here rather than
			// at persistence time to preserve the raw record.
			if strings.TrimSpace(part.Text) == "" {
				continue
			}
			result = append(result, fantasy.TextPart{
				Text:            part.Text,
				ProviderOptions: providerMetadataToOptions(logger, part.ProviderMetadata),
			})
		case codersdk.ChatMessagePartTypeReasoning:
			opts := providerMetadataToOptions(logger, part.ProviderMetadata)
			if strings.TrimSpace(part.Text) == "" && !chatsanitize.HasAnthropicSignedReasoningOptions(opts) {
				continue
			}
			result = append(result, fantasy.ReasoningPart{
				Text:            part.Text,
				ProviderOptions: opts,
			})
		case codersdk.ChatMessagePartTypeToolCall:
			result = append(result, fantasy.ToolCallPart{
				ToolCallID:       sanitizeToolCallID(part.ToolCallID),
				ToolName:         part.ToolName,
				Input:            string(part.Args),
				ProviderExecuted: part.ProviderExecuted,
				ProviderOptions:  providerMetadataToOptions(logger, part.ProviderMetadata),
			})
		case codersdk.ChatMessagePartTypeToolResult:
			result = append(result, toolResultPartToMessagePart(logger, part))
		case codersdk.ChatMessagePartTypeFile:
			data := part.Data
			mediaType := part.MediaType
			var name string
			resolvedFile := false
			if part.FileID.Valid {
				if fd, ok := resolved[part.FileID.UUID]; ok {
					resolvedFile = true
					data = fd.Data
					name = fd.Name
					if mediaType == "" {
						mediaType = fd.MediaType
					}
				}
			}
			opts := providerMetadataToOptions(logger, part.ProviderMetadata)