create_from_mermaid

Instructions

Implementation Reference

• src/mcp/index.ts:463-490 (handler)

  Tool registration and inline handler implementation for create_from_mermaid. This is the actual executing code that parses mermaidDiagram and config, calls client.convertMermaid(), and returns success/error messages.

  // --- Tool: create_from_mermaid ---
  server.tool(
    'create_from_mermaid',
    'Convert a Mermaid diagram to Excalidraw elements',
    {
      mermaidDiagram: z.string().min(1).max(LIMITS.MAX_MERMAID_LENGTH),
      config: z.object({
        startOnLoad: z.boolean().optional(),
        flowchart: z.object({ curve: z.enum(['linear', 'basis']).optional() }).optional(),
        themeVariables: z.object({ fontSize: z.string().max(10).optional() }).optional(),
        maxEdges: z.number().int().min(1).max(1000).optional(),
        maxTextSize: z.number().int().min(1).max(100000).optional(),
      }).optional(),
    },
    async ({ mermaidDiagram, config }) => {
      try {
        await client.convertMermaid(mermaidDiagram, config as Record<string, unknown>);
        return {
          content: [{
            type: 'text',
            text: 'Mermaid conversion broadcast to canvas. Elements will appear when a frontend client is connected.',
          }],
        };
      } catch (err) {
        return { content: [{ type: 'text', text: `Error: ${(err as Error).message}` }], isError: true };
      }
    }
  );

• src/mcp/schemas/element.ts:194-214 (schema)

  Zod schema definition for Mermaid diagram conversion input validation. Defines the structure for mermaidDiagram string and optional config object.

  export const MermaidSchema = z
    .object({
      mermaidDiagram: z.string().min(1).max(LIMITS.MAX_MERMAID_LENGTH),
      config: z
        .object({
          startOnLoad: z.boolean().optional(),
          flowchart: z
            .object({})
            .strict()
            .optional(),
          themeVariables: z
            .object({})
            .strict()
            .optional(),
          maxEdges: z.number().int().min(1).max(1000).optional(),
          maxTextSize: z.number().int().min(1).max(100_000).optional(),
        })
        .strict()
        .optional(),
    })
    .strict();

• src/mcp/canvas-client.ts:148-162 (helper)

  CanvasClient method that performs the actual HTTP POST request to /api/elements/from-mermaid endpoint with the mermaid diagram and config.

  async convertMermaid(
    mermaidDiagram: string,
    config?: Record<string, unknown>
  ): Promise<void> {
    const res = await fetch(`${this.baseUrl}/api/elements/from-mermaid`, {
      method: 'POST',
      headers: this.headers(),
      body: JSON.stringify({ mermaidDiagram, config }),
    });
  
    if (!res.ok) {
      const body = await res.json().catch(() => ({})) as ApiResponse;
      throw new Error(body.error ?? `Canvas error: ${res.status}`);
    }
  }

• src/mcp/tools/create-from-mermaid.ts:1-14 (helper)

  Alternative exported handler function that uses MermaidSchema for validation and calls client.convertMermaid(). Note: This function is exported but not currently used by the MCP server registration.

  import type { CanvasClient } from '../canvas-client.js';
  import { MermaidSchema } from '../schemas/element.js';
  
  export async function createFromMermaidTool(
    args: unknown,
    client: CanvasClient
  ) {
    const { mermaidDiagram, config } = MermaidSchema.parse(args);
    await client.convertMermaid(
      mermaidDiagram,
      config as Record<string, unknown> | undefined
    );
    return { success: true, message: 'Mermaid conversion sent to canvas' };
  }

• src/mcp/index.ts:572-572 (registration)

  Sandbox server registration for capability scanning. This is a noop registration used for Smithery capability detection.

  server.tool('create_from_mermaid', 'Convert a Mermaid diagram to Excalidraw elements', { mermaidDiagram: z.string().min(1).max(LIMITS.MAX_MERMAID_LENGTH) }, noop);