Select Layer

Instructions

Implementation Reference

• src/tools/layer.ts:76-89 (handler)

  Handler registration for photopea_select_layer tool. Calls buildSelectLayer to generate the Photopea JS script, executes it via the bridge, and returns a success/error result.

  server.registerTool("photopea_select_layer", {
    title: "Select Layer",
    description: "Set a layer as the active layer by name or index. Many tools (apply_filter, apply_adjustment, fill_selection) operate on the active layer — use this to target a specific layer first. Use get_layers to find layer names and indices.",
    inputSchema: {
      target: layerTarget,
    },
    annotations: { readOnlyHint: false, destructiveHint: false, idempotentHint: true, openWorldHint: false },
  }, async (params) => {
    const script = buildSelectLayer({ target: params.target });
    bridge.sendActivity({ type: "activity", id: "", tool: "select_layer", summary: `Select layer: ${params.target}` });
    const result = await bridge.executeScript(script);
    if (!result.success) return { isError: true, content: [{ type: "text" as const, text: result.error || "Failed to select layer" }] };
    return { content: [{ type: "text" as const, text: `Layer selected: ${params.target}` }] };
  });

• src/bridge/script-builder.ts:261-267 (helper)

  Builds the JavaScript string to set a layer as active in Photopea. Uses layerRef helper to resolve the target (by name string or numeric index).

  export function buildSelectLayer(params: LayerTarget): string {
    const ref = layerRef(params.target);
    return [
      `app.activeDocument.activeLayer = ${ref};`,
      `app.echoToOE('ok');`,
    ].join("\n");
  }

• src/bridge/script-builder.ts:57-62 (helper)

  Helper function that emits a JS expression resolving to a layer — by numeric index (app.activeDocument.layers[index]) or by name string (app.activeDocument.layers.getByName(...)).

  function layerRef(target: string | number): string {
    if (typeof target === "number") {
      return `app.activeDocument.layers[${target}]`;
    }
    return `app.activeDocument.layers.getByName('${escapeString(target)}')`;
  }

• src/bridge/types.ts:100-102 (schema)

  TypeScript interface defining the LayerTarget type used by buildSelectLayer and other layer-related script builders.

  export interface LayerTarget {
    target: string | number;
  }

• src/tools/layer.ts:6-22 (registration)

  Import of buildSelectLayer from script-builder and definition of layerTarget zod schema used in the tool registration.

  import {
    buildAddLayer,
    buildAddFillLayer,
    buildDeleteLayer,
    buildSelectLayer,
    buildSetLayerProperties,
    buildMoveLayer,
    buildDuplicateLayer,
    buildReorderLayer,
    buildGroupLayers,
    buildGetLayers,
    escapeString,
  } from "../bridge/script-builder.js";
  
  const layerTarget = z.union([z.string(), z.number()]).describe("Layer name (string) or index (number)");
  
  export function registerLayerTools(server: McpServer, bridge: PhotopeaBridge): void {