Method createFrontmatterError

pkg/workflow/frontmatter_error.go:76–138

createFrontmatterError creates a detailed error for frontmatter parsing issues frontmatterLineOffset is the line number where the frontmatter content begins (1-based) Returns error in VSCode-compatible format: filename:line:column: error message

(filePath, content string, err error, frontmatterLineOffset int)

// frontmatterLineOffset is the line number where the frontmatter content begins (1-based)
// Returns error in VSCode-compatible format: filename:line:column: error message
func (c *Compiler) createFrontmatterError(filePath, content string, err error, frontmatterLineOffset int) error {
	frontmatterErrorLog.Printf("Creating frontmatter error for file: %s, offset: %d", filePath, frontmatterLineOffset)

	errorStr := err.Error()

	// Check if error already contains formatted yaml.FormatError() output with source context
	// yaml.FormatError() produces output like "failed to parse frontmatter:\n[line:col] message\n>  line | content..."
	if strings.Contains(errorStr, frontmatterParseErrPrefix+"[") && (strings.Contains(errorStr, "\n>") || strings.Contains(errorStr, "|")) {
		// Extract line and column from the formatted error for VSCode compatibility
		// Pattern: [line:col] message
		if matches := lineColPattern.FindStringSubmatch(errorStr); len(matches) >= 4 {
			line := matches[1]
			col := matches[2]
			message := matches[3]
			// Extract just the first line of the message (before newline)
			if idx := strings.Index(message, "\n"); idx != -1 {
				message = message[:idx]
			}
			// Translate raw YAML parser messages to user-friendly plain English.
			// Uses the shared translation table from pkg/parser to keep both code paths in sync.
			message = parser.TranslateYAMLMessage(message)

			// Format as: filename:line:column: error: message
			// This is compatible with VSCode's problem matcher
			vscodeFormat := fmt.Sprintf("%s:%s:%s: error: %s", filePath, line, col, message)

			// Extract just the source context lines (skip the [line:col] message line to avoid duplication)
			// Find the first line that starts with whitespace + digit + | (source context line)
			if loc := sourceContextPattern.FindStringIndex(errorStr); loc != nil {
				// Extract from the first source context line to the end
				context := errorStr[loc[0]+1:] // +1 to skip the leading newline
				// Return VSCode-compatible format on first line, followed by source context only
				frontmatterErrorLog.Print("Formatting error for VSCode compatibility")
				return parser.NewFormattedParserError(fmt.Sprintf("%s\n%s", vscodeFormat, context))
			}

			// If we can't extract source context, return just the VSCode format
			return parser.NewFormattedParserError(vscodeFormat)
		}

		// Fallback if we can't parse the line/col: emit an IDE-compatible error
		// pointing to the frontmatter start so the developer is at least brought to
		// the right section rather than the useless line 1, col 1.
		frontmatterErrorLog.Print("Could not extract line/col from formatted error, falling back to frontmatter start")
		fallbackMsg := "failed to parse YAML frontmatter"
		// Try to surface a single-line description from the raw error text.
		if _, rest, found := strings.Cut(errorStr, frontmatterParseErrPrefix); found {
			firstLine, _, _ := strings.Cut(rest, "\n")
			if translated := parser.TranslateYAMLMessage(strings.TrimSpace(firstLine)); translated != "" {
				fallbackMsg = "failed to parse YAML frontmatter: " + translated
			}
		}
		fallbackFmt := fmt.Sprintf("%s:%d:1: error: %s", filePath, frontmatterLineOffset, fallbackMsg)
		return parser.NewFormattedParserError(fallbackFmt)
	}

	// Fallback: if not already formatted, create a FormattedParserError pointing to the
	// frontmatter start so the IDE navigates to the right file and section rather than