mirror of
https://github.com/DayuanJiang/next-ai-draw-io.git
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037f32973a
- Update biome schema version from 2.3.8 to 2.3.10 - Add radix parameter to parseInt in mcp-server - Remove unnecessary React fragment in model-config-dialog - Fix unused variable errors (err -> _err) - Auto-format code with biome
661 lines
23 KiB
JavaScript
661 lines
23 KiB
JavaScript
#!/usr/bin/env node
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/**
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* MCP Server for Next AI Draw.io
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*
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* Enables AI agents (Claude Desktop, Cursor, etc.) to generate and edit
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* draw.io diagrams with real-time browser preview.
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*
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* Uses an embedded HTTP server - no external dependencies required.
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*/
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// Setup DOM polyfill for Node.js (required for XML operations)
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import { DOMParser } from "linkedom"
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;(globalThis as any).DOMParser = DOMParser
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// Create XMLSerializer polyfill using outerHTML
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class XMLSerializerPolyfill {
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serializeToString(node: any): string {
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if (node.outerHTML !== undefined) {
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return node.outerHTML
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}
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if (node.documentElement) {
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return node.documentElement.outerHTML
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}
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return ""
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}
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}
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;(globalThis as any).XMLSerializer = XMLSerializerPolyfill
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import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js"
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import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js"
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import open from "open"
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import { z } from "zod"
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import {
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applyDiagramOperations,
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type DiagramOperation,
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} from "./diagram-operations.js"
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import { addHistory } from "./history.js"
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import {
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getState,
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requestSync,
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setState,
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shutdown,
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startHttpServer,
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waitForSync,
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} from "./http-server.js"
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import { log } from "./logger.js"
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import { validateAndFixXml } from "./xml-validation.js"
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// Server configuration
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const config = {
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port: parseInt(process.env.PORT || "6002", 10),
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}
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// Session state (single session for simplicity)
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let currentSession: {
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id: string
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xml: string
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version: number
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lastGetDiagramTime: number // Track when get_diagram was last called (for enforcing workflow)
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} | null = null
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// Create MCP server
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const server = new McpServer({
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name: "next-ai-drawio",
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version: "0.1.2",
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})
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// Register prompt with workflow guidance
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server.prompt(
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"diagram-workflow",
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"Guidelines for creating and editing draw.io diagrams",
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() => ({
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messages: [
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{
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role: "user",
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content: {
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type: "text",
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text: `# Draw.io Diagram Workflow Guidelines
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## Creating a New Diagram
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1. Call start_session to open the browser preview
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2. Use create_new_diagram with complete mxGraphModel XML to create a new diagram
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## Adding Elements to Existing Diagram
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1. Use edit_diagram with "add" operation
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2. Provide a unique cell_id and complete mxCell XML
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3. No need to call get_diagram first - the server fetches latest state automatically
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## Modifying or Deleting Existing Elements
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1. FIRST call get_diagram to see current cell IDs and structure
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2. THEN call edit_diagram with "update" or "delete" operations
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3. For update, provide the cell_id and complete new mxCell XML
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## Important Notes
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- create_new_diagram REPLACES the entire diagram - only use for new diagrams
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- edit_diagram PRESERVES user's manual changes (fetches browser state first)
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- Always use unique cell_ids when adding elements (e.g., "shape-1", "arrow-2")`,
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},
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},
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],
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}),
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)
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// Tool: start_session
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server.registerTool(
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"start_session",
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{
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description:
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"Start a new diagram session and open the browser for real-time preview. " +
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"Starts an embedded server and opens a browser window with draw.io. " +
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"The browser will show diagram updates as they happen.",
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inputSchema: {},
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},
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async () => {
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try {
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// Start embedded HTTP server
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const port = await startHttpServer(config.port)
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// Create session
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const sessionId = `mcp-${Date.now().toString(36)}-${Math.random().toString(36).substring(2, 8)}`
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currentSession = {
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id: sessionId,
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xml: "",
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version: 0,
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lastGetDiagramTime: 0,
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}
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// Open browser
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const browserUrl = `http://localhost:${port}?mcp=${sessionId}`
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await open(browserUrl)
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log.info(`Started session ${sessionId}, browser at ${browserUrl}`)
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return {
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content: [
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{
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type: "text",
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text: `Session started successfully!\n\nSession ID: ${sessionId}\nBrowser URL: ${browserUrl}\n\nThe browser will now show real-time diagram updates.`,
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},
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],
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}
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} catch (error) {
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const message =
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error instanceof Error ? error.message : String(error)
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log.error("start_session failed:", message)
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return {
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content: [{ type: "text", text: `Error: ${message}` }],
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isError: true,
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}
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}
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},
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)
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// Tool: create_new_diagram
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server.registerTool(
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"create_new_diagram",
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{
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description: `Create a NEW diagram from mxGraphModel XML. Use this when creating a diagram from scratch or replacing the current diagram entirely.
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CRITICAL: You MUST provide the 'xml' argument in EVERY call. Do NOT call this tool without xml.
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When to use this tool:
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- Creating a new diagram from scratch
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- Replacing the current diagram with a completely different one
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- Major structural changes that require regenerating the diagram
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When to use edit_diagram instead:
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- Small modifications to existing diagram
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- Adding/removing individual elements
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- Changing labels, colors, or positions
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XML FORMAT - Full mxGraphModel structure:
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<mxGraphModel>
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<root>
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<mxCell id="0"/>
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<mxCell id="1" parent="0"/>
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<mxCell id="2" value="Shape" style="rounded=1;" vertex="1" parent="1">
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<mxGeometry x="100" y="100" width="120" height="60" as="geometry"/>
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</mxCell>
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</root>
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</mxGraphModel>
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LAYOUT CONSTRAINTS:
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- Keep all elements within x=0-800, y=0-600 (single page viewport)
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- Start from margins (x=40, y=40), keep elements grouped closely
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- Use unique IDs starting from "2" (0 and 1 are reserved)
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- Set parent="1" for top-level shapes
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- Space shapes 150-200px apart for clear edge routing
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EDGE ROUTING RULES:
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- Never let multiple edges share the same path - use different exitY/entryY values
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- For bidirectional connections (A↔B), use OPPOSITE sides
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- Always specify exitX, exitY, entryX, entryY explicitly in edge style
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- Route edges AROUND obstacles using waypoints (add 20-30px clearance)
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- Use natural connection points based on flow (not corners)
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COMMON STYLES:
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- Shapes: rounded=1; fillColor=#hex; strokeColor=#hex
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- Edges: endArrow=classic; edgeStyle=orthogonalEdgeStyle; curved=1
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- Text: fontSize=14; fontStyle=1 (bold); align=center`,
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inputSchema: {
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xml: z
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.string()
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.describe(
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"REQUIRED: The complete mxGraphModel XML. Must always be provided.",
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),
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},
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},
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async ({ xml: inputXml }) => {
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try {
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if (!currentSession) {
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return {
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content: [
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{
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type: "text",
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text: "Error: No active session. Please call start_session first.",
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},
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],
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isError: true,
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}
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}
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// Validate and auto-fix XML
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let xml = inputXml
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const { valid, error, fixed, fixes } = validateAndFixXml(xml)
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if (fixed) {
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xml = fixed
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log.info(`XML auto-fixed: ${fixes.join(", ")}`)
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}
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if (!valid && error) {
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log.error(`XML validation failed: ${error}`)
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return {
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content: [
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{
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type: "text",
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text: `Error: XML validation failed - ${error}`,
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},
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],
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isError: true,
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}
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}
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log.info(`Setting diagram content, ${xml.length} chars`)
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// Sync from browser state first
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const browserState = getState(currentSession.id)
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if (browserState?.xml) {
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currentSession.xml = browserState.xml
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}
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// Save user's state before AI overwrites (with cached SVG)
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if (currentSession.xml) {
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addHistory(
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currentSession.id,
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currentSession.xml,
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browserState?.svg || "",
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)
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}
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// Update session state
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currentSession.xml = xml
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currentSession.version++
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// Push to embedded server state
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setState(currentSession.id, xml)
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// Save AI result (no SVG yet - will be captured by browser)
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addHistory(currentSession.id, xml, "")
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log.info(`Diagram content set successfully`)
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return {
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content: [
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{
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type: "text",
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text: `Diagram content set successfully!\n\nThe diagram is now visible in your browser.\n\nXML length: ${xml.length} characters`,
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},
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],
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}
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} catch (error) {
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const message =
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error instanceof Error ? error.message : String(error)
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log.error("create_new_diagram failed:", message)
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return {
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content: [{ type: "text", text: `Error: ${message}` }],
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isError: true,
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}
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}
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},
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)
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// Tool: edit_diagram
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server.registerTool(
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"edit_diagram",
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{
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description:
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"Edit the current diagram by ID-based operations (update/add/delete cells).\n\n" +
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"⚠️ REQUIRED: You MUST call get_diagram BEFORE this tool!\n" +
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"This fetches the latest state from the browser including any manual user edits.\n" +
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"Skipping get_diagram WILL cause user's changes to be LOST.\n\n" +
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"Workflow:\n" +
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"1. Call get_diagram to see current cell IDs and structure\n" +
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"2. Use the returned XML to construct your edit operations\n" +
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"3. Call edit_diagram with your operations\n\n" +
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"Operations:\n" +
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"- add: Add a new cell. Provide cell_id (new unique id) and new_xml.\n" +
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"- update: Replace an existing cell by its id. Provide cell_id and complete new_xml.\n" +
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"- delete: Remove a cell by its id. Only cell_id is needed.\n\n" +
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"For add/update, new_xml must be a complete mxCell element including mxGeometry.\n\n" +
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"Example - Add a rectangle:\n" +
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'{"operations": [{"operation": "add", "cell_id": "rect-1", "new_xml": "<mxCell id=\\"rect-1\\" value=\\"Hello\\" style=\\"rounded=0;\\" vertex=\\"1\\" parent=\\"1\\"><mxGeometry x=\\"100\\" y=\\"100\\" width=\\"120\\" height=\\"60\\" as=\\"geometry\\"/></mxCell>"}]}\n\n' +
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"Example - Update a cell:\n" +
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'{"operations": [{"operation": "update", "cell_id": "3", "new_xml": "<mxCell id=\\"3\\" value=\\"New Label\\" style=\\"rounded=1;\\" vertex=\\"1\\" parent=\\"1\\"><mxGeometry x=\\"100\\" y=\\"100\\" width=\\"120\\" height=\\"60\\" as=\\"geometry\\"/></mxCell>"}]}\n\n' +
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"Example - Delete a cell:\n" +
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'{"operations": [{"operation": "delete", "cell_id": "rect-1"}]}',
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inputSchema: {
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operations: z
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.array(
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z.object({
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operation: z
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.enum(["update", "add", "delete"])
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.describe(
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"Operation to perform: add, update, or delete",
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),
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cell_id: z.string().describe("The id of the mxCell"),
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new_xml: z
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.string()
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.optional()
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.describe(
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"Complete mxCell XML element (required for update/add)",
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),
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}),
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)
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.describe("Array of operations to apply"),
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},
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},
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async ({ operations }) => {
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try {
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if (!currentSession) {
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return {
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content: [
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{
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type: "text",
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text: "Error: No active session. Please call start_session first.",
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},
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],
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isError: true,
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}
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}
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// Enforce workflow: require get_diagram to be called first
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const timeSinceGet = Date.now() - currentSession.lastGetDiagramTime
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if (timeSinceGet > 30000) {
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// 30 seconds
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log.warn(
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"edit_diagram called without recent get_diagram - rejecting to prevent data loss",
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)
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return {
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content: [
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{
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type: "text",
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text:
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"Error: You must call get_diagram first before edit_diagram.\n\n" +
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"This ensures you have the latest diagram state including any manual edits the user made in the browser. " +
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"Please call get_diagram, then use that XML to construct your edit operations.",
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},
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],
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isError: true,
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}
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}
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// Fetch latest state from browser
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const browserState = getState(currentSession.id)
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if (browserState?.xml) {
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currentSession.xml = browserState.xml
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log.info("Fetched latest diagram state from browser")
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}
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if (!currentSession.xml) {
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return {
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content: [
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{
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type: "text",
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text: "Error: No diagram to edit. Please create a diagram first with create_new_diagram.",
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},
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],
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isError: true,
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}
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}
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log.info(`Editing diagram with ${operations.length} operation(s)`)
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// Save before editing (with cached SVG from browser)
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addHistory(
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currentSession.id,
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currentSession.xml,
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browserState?.svg || "",
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)
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// Validate and auto-fix new_xml for each operation
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const validatedOps = operations.map((op) => {
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if (op.new_xml) {
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const { valid, error, fixed, fixes } = validateAndFixXml(
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op.new_xml,
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)
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if (fixed) {
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log.info(
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`Operation ${op.operation} ${op.cell_id}: XML auto-fixed: ${fixes.join(", ")}`,
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)
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return { ...op, new_xml: fixed }
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}
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if (!valid && error) {
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log.warn(
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`Operation ${op.operation} ${op.cell_id}: XML validation failed: ${error}`,
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)
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}
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}
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return op
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})
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// Apply operations
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const { result, errors } = applyDiagramOperations(
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currentSession.xml,
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validatedOps as DiagramOperation[],
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)
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if (errors.length > 0) {
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const errorMessages = errors
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.map((e) => `${e.type} ${e.cellId}: ${e.message}`)
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.join("\n")
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log.warn(`Edit had ${errors.length} error(s): ${errorMessages}`)
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}
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// Update state
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currentSession.xml = result
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currentSession.version++
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// Push to embedded server
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setState(currentSession.id, result)
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// Save AI result (no SVG yet - will be captured by browser)
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addHistory(currentSession.id, result, "")
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log.info(`Diagram edited successfully`)
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const successMsg = `Diagram edited successfully!\n\nApplied ${operations.length} operation(s).`
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const errorMsg =
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errors.length > 0
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? `\n\nWarnings:\n${errors.map((e) => `- ${e.type} ${e.cellId}: ${e.message}`).join("\n")}`
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: ""
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return {
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content: [
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{
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type: "text",
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text: successMsg + errorMsg,
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},
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],
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}
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} catch (error) {
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const message =
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error instanceof Error ? error.message : String(error)
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log.error("edit_diagram failed:", message)
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return {
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content: [{ type: "text", text: `Error: ${message}` }],
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isError: true,
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}
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}
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},
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)
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// Tool: get_diagram
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server.registerTool(
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"get_diagram",
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{
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description:
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"Get the current diagram XML (fetches latest from browser, including user's manual edits). " +
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"Call this BEFORE edit_diagram if you need to update or delete existing elements, " +
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"so you can see the current cell IDs and structure.",
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},
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async () => {
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try {
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if (!currentSession) {
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return {
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content: [
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{
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type: "text",
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text: "Error: No active session. Please call start_session first.",
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},
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],
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isError: true,
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}
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}
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// Request browser to push fresh state and wait for it
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const syncRequested = requestSync(currentSession.id)
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if (syncRequested) {
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const synced = await waitForSync(currentSession.id)
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if (!synced) {
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log.warn("get_diagram: sync timeout - state may be stale")
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}
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}
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// Mark that get_diagram was called (for edit_diagram workflow check)
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currentSession.lastGetDiagramTime = Date.now()
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// Fetch latest state from browser
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const browserState = getState(currentSession.id)
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if (browserState?.xml) {
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currentSession.xml = browserState.xml
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}
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if (!currentSession.xml) {
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return {
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content: [
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{
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type: "text",
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text: "No diagram exists yet. Use create_new_diagram to create one.",
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},
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],
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}
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}
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return {
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content: [
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{
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type: "text",
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text: `Current diagram XML:\n\n${currentSession.xml}`,
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},
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],
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}
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} catch (error) {
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const message =
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error instanceof Error ? error.message : String(error)
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log.error("get_diagram failed:", message)
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return {
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content: [{ type: "text", text: `Error: ${message}` }],
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isError: true,
|
|
}
|
|
}
|
|
},
|
|
)
|
|
|
|
// Tool: export_diagram
|
|
server.registerTool(
|
|
"export_diagram",
|
|
{
|
|
description: "Export the current diagram to a .drawio file.",
|
|
inputSchema: {
|
|
path: z
|
|
.string()
|
|
.describe(
|
|
"File path to save the diagram (e.g., ./diagram.drawio)",
|
|
),
|
|
},
|
|
},
|
|
async ({ path }) => {
|
|
try {
|
|
if (!currentSession) {
|
|
return {
|
|
content: [
|
|
{
|
|
type: "text",
|
|
text: "Error: No active session. Please call start_session first.",
|
|
},
|
|
],
|
|
isError: true,
|
|
}
|
|
}
|
|
|
|
// Fetch latest state
|
|
const browserState = getState(currentSession.id)
|
|
if (browserState?.xml) {
|
|
currentSession.xml = browserState.xml
|
|
}
|
|
|
|
if (!currentSession.xml) {
|
|
return {
|
|
content: [
|
|
{
|
|
type: "text",
|
|
text: "Error: No diagram to export. Please create a diagram first.",
|
|
},
|
|
],
|
|
isError: true,
|
|
}
|
|
}
|
|
|
|
const fs = await import("node:fs/promises")
|
|
const nodePath = await import("node:path")
|
|
|
|
let filePath = path
|
|
if (!filePath.endsWith(".drawio")) {
|
|
filePath = `${filePath}.drawio`
|
|
}
|
|
|
|
const absolutePath = nodePath.resolve(filePath)
|
|
await fs.writeFile(absolutePath, currentSession.xml, "utf-8")
|
|
|
|
log.info(`Diagram exported to ${absolutePath}`)
|
|
|
|
return {
|
|
content: [
|
|
{
|
|
type: "text",
|
|
text: `Diagram exported successfully!\n\nFile: ${absolutePath}\nSize: ${currentSession.xml.length} characters`,
|
|
},
|
|
],
|
|
}
|
|
} catch (error) {
|
|
const message =
|
|
error instanceof Error ? error.message : String(error)
|
|
log.error("export_diagram failed:", message)
|
|
return {
|
|
content: [{ type: "text", text: `Error: ${message}` }],
|
|
isError: true,
|
|
}
|
|
}
|
|
},
|
|
)
|
|
|
|
// Graceful shutdown handler
|
|
let isShuttingDown = false
|
|
function gracefulShutdown(reason: string) {
|
|
if (isShuttingDown) return
|
|
isShuttingDown = true
|
|
log.info(`Shutting down: ${reason}`)
|
|
shutdown()
|
|
process.exit(0)
|
|
}
|
|
|
|
// Handle stdin close (primary method - works on all platforms including Windows)
|
|
process.stdin.on("close", () => gracefulShutdown("stdin closed"))
|
|
process.stdin.on("end", () => gracefulShutdown("stdin ended"))
|
|
|
|
// Handle signals (may not work reliably on Windows)
|
|
process.on("SIGINT", () => gracefulShutdown("SIGINT"))
|
|
process.on("SIGTERM", () => gracefulShutdown("SIGTERM"))
|
|
|
|
// Handle broken pipe (writing to closed stdout)
|
|
process.stdout.on("error", (err) => {
|
|
if (err.code === "EPIPE" || err.code === "ERR_STREAM_DESTROYED") {
|
|
gracefulShutdown("stdout error")
|
|
}
|
|
})
|
|
|
|
// Start the MCP server
|
|
async function main() {
|
|
log.info("Starting MCP server for Next AI Draw.io (embedded mode)...")
|
|
|
|
const transport = new StdioServerTransport()
|
|
await server.connect(transport)
|
|
|
|
log.info("MCP server running on stdio")
|
|
}
|
|
|
|
main().catch((error) => {
|
|
log.error("Fatal error:", error)
|
|
process.exit(1)
|
|
})
|