MCP Index Notes

Instructions

Implementation Reference

• src/mcp.ts:1370-1397 (handler)

  Executes the image-upsert tool: validates input with ImageUpsertSchema, loads image data from base64 or file path, guesses MIME type if needed, calls db.insertImage, returns the new image ID.

  case 'image-upsert': {
    const parsed = ImageUpsertSchema.parse(args);
    if (!('insertImage' in (db as any))) {
      throw new Error('Image storage not supported in current store implementation');
    }
    const fs = await import('fs');
    let raw: Buffer | null = null;
    if (parsed.data) {
      raw = Buffer.from(parsed.data, 'base64');
    } else if (parsed.file) {
        raw = fs.readFileSync(parsed.file);
    } else {
      throw new Error('Provide data (base64) or file');
    }
    // crude mime guess if not provided
    let mime = parsed.mime;
    if (!mime && parsed.file) {
      const ext = parsed.file.toLowerCase();
      if (ext.endsWith('.png')) mime = 'image/png';
      else if (ext.endsWith('.jpg') || ext.endsWith('.jpeg')) mime = 'image/jpeg';
      else if (ext.endsWith('.gif')) mime = 'image/gif';
      else if (ext.endsWith('.webp')) mime = 'image/webp';
      else mime = 'application/octet-stream';
    }
    if (!mime) mime = 'application/octet-stream';
    const id = (db as any).insertImage({ key: parsed.key, mime, data: raw!, metadata: parsed.metadata });
    return { content: [{ type: 'text', text: JSON.stringify({ id }) }] };
  }

• src/types.ts:93-101 (schema)

  Zod input schema for image-upsert tool defining key (required), optional data (base64), file path, mime type, and metadata.

  export const ImageUpsertSchema = z.object({
    key: z.string().min(1, 'key is required'),
    // Either provide raw base64 data (without data:mime prefix) or a file path to read
    data: z.string().optional(),
    file: z.string().optional(),
    mime: z.string().optional(),
    metadata: z.record(z.any()).optional().default({}),
  });
  export type ImageUpsertInput = z.infer<typeof ImageUpsertSchema>;

• src/mcp.ts:62-75 (registration)

  MCP tool registration defining name 'image-upsert', description, and inputSchema (JSON schema version of the Zod schema).

    name: 'image-upsert',
    description: 'Store an image (base64 data or file path) under a key. Returns image id.',
    inputSchema: {
      type: 'object',
      properties: {
        key: { type: 'string' },
        data: { type: 'string', description: 'Base64-encoded image data (no data: prefix)' },
        file: { type: 'string', description: 'Path to image file to read if data not provided' },
        mime: { type: 'string', description: 'MIME type e.g. image/png if data provided' },
        metadata: { type: 'object' },
      },
      required: ['key'],
    },
  },

• src/db.ts:193-203 (helper)

  Database helper method that inserts image record into SQLite 'images' table, storing key, mime, size, metadata (JSON), and binary data (BLOB), returns inserted ID.

  insertImage(img: { key: string; mime: string; data: Buffer; metadata?: any }): number {
    const stmt = this.db.prepare(`INSERT INTO images (key, mime, size, metadata, data) VALUES (@key, @mime, @size, @metadata, @data)`);
    const info = stmt.run({
      key: img.key,
      mime: img.mime,
      size: img.data.length,
      metadata: JSON.stringify(img.metadata ?? {}),
      data: img.data,
    });
    return Number(info.lastInsertRowid);
  }