/**
* Custom error classes for W3C MCP Server
*/
import type { z } from 'zod';
/**
* Base class for W3C MCP errors
*/
export class W3CMCPError extends Error {
constructor(message: string) {
super(message);
this.name = 'W3CMCPError';
}
}
/**
* Spec not found error with suggestions
*/
export class SpecNotFoundError extends W3CMCPError {
public suggestions?: string[];
constructor(shortname: string, suggestions?: string[]) {
const message = suggestions?.length
? `Specification "${shortname}" not found. Did you mean: ${suggestions.join(', ')}?`
: `Specification "${shortname}" not found.`;
super(message);
this.name = 'SpecNotFoundError';
this.suggestions = suggestions;
}
}
/**
* WebIDL not found error
*/
export class WebIDLNotFoundError extends W3CMCPError {
constructor(shortname: string) {
super(
`WebIDL not found for "${shortname}". This specification might not have WebIDL definitions.`,
);
this.name = 'WebIDLNotFoundError';
}
}
/**
* CSS data not found error
*/
export class CSSNotFoundError extends W3CMCPError {
constructor(spec: string, availableSpecs?: string[]) {
const message = availableSpecs?.length
? `CSS data not found for "${spec}". Available CSS specs: ${availableSpecs.slice(0, 10).join(', ')}...`
: `CSS data not found for "${spec}".`;
super(message);
this.name = 'CSSNotFoundError';
}
}
/**
* Elements data not found error
*/
export class ElementsNotFoundError extends W3CMCPError {
constructor(spec: string, availableSpecs?: string[]) {
const message = availableSpecs?.length
? `Elements data not found for "${spec}". Available specs: ${availableSpecs.join(', ')}`
: `Elements data not found for "${spec}".`;
super(message);
this.name = 'ElementsNotFoundError';
}
}
/**
* Validation error wrapper
*/
export class ValidationError extends W3CMCPError {
public zodError: z.ZodError;
constructor(zodError: z.ZodError) {
const issues = zodError.issues.map((i) => `${i.path.join('.')}: ${i.message}`).join('; ');
super(`Validation error: ${issues}`);
this.name = 'ValidationError';
this.zodError = zodError;
}
}
/**
* Format error response for MCP
*/
export function formatErrorResponse(error: unknown): { text: string; errorType: string } {
if (error instanceof ValidationError) {
return {
text: JSON.stringify(
{
error: 'ValidationError',
message: error.message,
issues: error.zodError.issues,
},
null,
2,
),
errorType: 'ValidationError',
};
}
if (error instanceof SpecNotFoundError) {
return {
text: JSON.stringify(
{
error: 'SpecNotFoundError',
message: error.message,
suggestions: error.suggestions,
},
null,
2,
),
errorType: 'SpecNotFoundError',
};
}
if (error instanceof W3CMCPError) {
return {
text: JSON.stringify(
{
error: error.name,
message: error.message,
},
null,
2,
),
errorType: error.name,
};
}
if (error instanceof Error) {
return {
text: `Error: ${error.message}`,
errorType: 'Error',
};
}
return {
text: 'An unknown error occurred',
errorType: 'UnknownError',
};
}
