fix: rename edit_diagram type field to operation for better model compatibility (#402)

Fixes #374 - Models were confused by the `type` field name and sent
`operation` instead. This change:

- Renames DiagramOperation.type to DiagramOperation.operation across
  all files (MCP server, web app, hooks, components, system prompts)
- Adds JSON examples in tool descriptions to show correct format
- Updates all test data to use the new field name

Affected files:
- lib/utils.ts
- app/api/chat/route.ts
- hooks/use-diagram-tool-handlers.ts
- components/chat-message-display.tsx
- lib/system-prompts.ts
- packages/mcp-server/src/diagram-operations.ts
- packages/mcp-server/src/index.ts
- scripts/test-diagram-operations.mjs

MCP server version bumped to 0.1.6

app/api/chat/route.ts

@@ -609,14 +609,22 @@ Operations:
 
 For update/add, new_xml must be a complete mxCell element including mxGeometry.
 
-⚠️ JSON ESCAPING: Every " inside new_xml MUST be escaped as \\". Example: id=\\"5\\" value=\\"Label\\"`,
+⚠️ JSON ESCAPING: Every " inside new_xml MUST be escaped as \\". Example: id=\\"5\\" value=\\"Label\\"
+
+Example - Add a rectangle:
+{"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>"}]}
+
+Example - Delete a cell:
+{"operations": [{"operation": "delete", "cell_id": "rect-1"}]}`,
                 inputSchema: z.object({
                     operations: z
                         .array(
                             z.object({
-                                type: z
+                                operation: z
                                     .enum(["update", "add", "delete"])
-                                    .describe("Operation type"),
+                                    .describe(
+                                        "Operation to perform: add, update, or delete",
+                                    ),
                                 cell_id: z
                                     .string()
                                     .describe(

components/chat-message-display.tsx

@@ -40,7 +40,7 @@ import ExamplePanel from "./chat-example-panel"
 import { CodeBlock } from "./code-block"
 
 interface DiagramOperation {
-    type: "update" | "add" | "delete"
+    operation: "update" | "add" | "delete"
     cell_id: string
     new_xml?: string
 }
@@ -53,12 +53,12 @@ function getCompleteOperations(
     return operations.filter(
         (op) =>
             op &&
-            typeof op.type === "string" &&
-            ["update", "add", "delete"].includes(op.type) &&
+            typeof op.operation === "string" &&
+            ["update", "add", "delete"].includes(op.operation) &&
             typeof op.cell_id === "string" &&
             op.cell_id.length > 0 &&
             // delete doesn't need new_xml, update/add do
-            (op.type === "delete" || typeof op.new_xml === "string"),
+            (op.operation === "delete" || typeof op.new_xml === "string"),
     )
 }
 
@@ -79,20 +79,20 @@ function OperationsDisplay({ operations }: { operations: DiagramOperation[] }) {
         <div className="space-y-3">
             {operations.map((op, index) => (
                 <div
-                    key={`${op.type}-${op.cell_id}-${index}`}
+                    key={`${op.operation}-${op.cell_id}-${index}`}
                     className="rounded-lg border border-border/50 overflow-hidden bg-background/50"
                 >
                     <div className="px-3 py-1.5 bg-muted/40 border-b border-border/30 flex items-center gap-2">
                         <span
                             className={`text-[10px] font-medium uppercase tracking-wide ${
-                                op.type === "delete"
+                                op.operation === "delete"
                                     ? "text-red-600"
-                                    : op.type === "add"
+                                    : op.operation === "add"
                                       ? "text-green-600"
                                       : "text-blue-600"
                             }`}
                         >
-                            {op.type}
+                            {op.operation}
                         </span>
                         <span className="text-xs text-muted-foreground">
                             cell_id: {op.cell_id}

hooks/use-diagram-tool-handlers.ts

@@ -30,7 +30,7 @@ type AddToolOutputParams = AddToolOutputSuccess | AddToolOutputError
 type AddToolOutputFn = (params: AddToolOutputParams) => void
 
 interface DiagramOperation {
-    type: "update" | "add" | "delete"
+    operation: "update" | "add" | "delete"
     cell_id: string
     new_xml?: string
 }

lib/system-prompts.ts

@@ -99,9 +99,9 @@ When using edit_diagram tool:
 - For update/add: provide cell_id and complete new_xml (full mxCell element including mxGeometry)
 - For delete: only cell_id is needed
 - Find the cell_id from "Current diagram XML" in system context
-- Example update: {"operations": [{"type": "update", "cell_id": "3", "new_xml": "<mxCell id=\\"3\\" value=\\"New Label\\" style=\\"rounded=1;\\" vertex=\\"1\\" parent=\\"1\\">\\n  <mxGeometry x=\\"100\\" y=\\"100\\" width=\\"120\\" height=\\"60\\" as=\\"geometry\\"/>\\n</mxCell>"}]}
-- Example delete: {"operations": [{"type": "delete", "cell_id": "5"}]}
-- Example add: {"operations": [{"type": "add", "cell_id": "new1", "new_xml": "<mxCell id=\\"new1\\" value=\\"New Box\\" style=\\"rounded=1;\\" vertex=\\"1\\" parent=\\"1\\">\\n  <mxGeometry x=\\"400\\" y=\\"200\\" width=\\"120\\" height=\\"60\\" as=\\"geometry\\"/>\\n</mxCell>"}]}
+- Example update: {"operations": [{"operation": "update", "cell_id": "3", "new_xml": "<mxCell id=\\"3\\" value=\\"New Label\\" style=\\"rounded=1;\\" vertex=\\"1\\" parent=\\"1\\">\\n  <mxGeometry x=\\"100\\" y=\\"100\\" width=\\"120\\" height=\\"60\\" as=\\"geometry\\"/>\\n</mxCell>"}]}
+- Example delete: {"operations": [{"operation": "delete", "cell_id": "5"}]}
+- Example add: {"operations": [{"operation": "add", "cell_id": "new1", "new_xml": "<mxCell id=\\"new1\\" value=\\"New Box\\" style=\\"rounded=1;\\" vertex=\\"1\\" parent=\\"1\\">\\n  <mxGeometry x=\\"400\\" y=\\"200\\" width=\\"120\\" height=\\"60\\" as=\\"geometry\\"/>\\n</mxCell>"}]}
 
 ⚠️ JSON ESCAPING: Every " inside new_xml MUST be escaped as \\". Example: id=\\"5\\" value=\\"Label\\"
 
@@ -282,9 +282,9 @@ edit_diagram uses ID-based operations to modify cells directly by their id attri
 \`\`\`json
 {
   "operations": [
-    {"type": "update", "cell_id": "3", "new_xml": "<mxCell ...complete element...>"},
-    {"type": "add", "cell_id": "new1", "new_xml": "<mxCell ...new element...>"},
-    {"type": "delete", "cell_id": "5"}
+    {"operation": "update", "cell_id": "3", "new_xml": "<mxCell ...complete element...>"},
+    {"operation": "add", "cell_id": "new1", "new_xml": "<mxCell ...new element...>"},
+    {"operation": "delete", "cell_id": "5"}
   ]
 }
 \`\`\`
@@ -293,17 +293,17 @@ edit_diagram uses ID-based operations to modify cells directly by their id attri
 
 Change label:
 \`\`\`json
-{"operations": [{"type": "update", "cell_id": "3", "new_xml": "<mxCell id=\\"3\\" value=\\"New Label\\" style=\\"rounded=1;\\" vertex=\\"1\\" parent=\\"1\\">\\n  <mxGeometry x=\\"100\\" y=\\"100\\" width=\\"120\\" height=\\"60\\" as=\\"geometry\\"/>\\n</mxCell>"}]}
+{"operations": [{"operation": "update", "cell_id": "3", "new_xml": "<mxCell id=\\"3\\" value=\\"New Label\\" style=\\"rounded=1;\\" vertex=\\"1\\" parent=\\"1\\">\\n  <mxGeometry x=\\"100\\" y=\\"100\\" width=\\"120\\" height=\\"60\\" as=\\"geometry\\"/>\\n</mxCell>"}]}
 \`\`\`
 
 Add new shape:
 \`\`\`json
-{"operations": [{"type": "add", "cell_id": "new1", "new_xml": "<mxCell id=\\"new1\\" value=\\"New Box\\" style=\\"rounded=1;fillColor=#dae8fc;\\" vertex=\\"1\\" parent=\\"1\\">\\n  <mxGeometry x=\\"400\\" y=\\"200\\" width=\\"120\\" height=\\"60\\" as=\\"geometry\\"/>\\n</mxCell>"}]}
+{"operations": [{"operation": "add", "cell_id": "new1", "new_xml": "<mxCell id=\\"new1\\" value=\\"New Box\\" style=\\"rounded=1;fillColor=#dae8fc;\\" vertex=\\"1\\" parent=\\"1\\">\\n  <mxGeometry x=\\"400\\" y=\\"200\\" width=\\"120\\" height=\\"60\\" as=\\"geometry\\"/>\\n</mxCell>"}]}
 \`\`\`
 
 Delete cell:
 \`\`\`json
-{"operations": [{"type": "delete", "cell_id": "5"}]}
+{"operations": [{"operation": "delete", "cell_id": "5"}]}
 \`\`\`
 
 **Error Recovery:**

lib/utils.ts

@@ -455,7 +455,7 @@ export function replaceNodes(currentXML: string, nodes: string): string {
 // ============================================================================
 
 export interface DiagramOperation {
-    type: "update" | "add" | "delete"
+    operation: "update" | "add" | "delete"
     cell_id: string
     new_xml?: string
 }
@@ -528,7 +528,7 @@ export function applyDiagramOperations(
 
     // Process each operation
     for (const op of operations) {
-        if (op.type === "update") {
+        if (op.operation === "update") {
             const existingCell = cellMap.get(op.cell_id)
             if (!existingCell) {
                 errors.push({
@@ -580,7 +580,7 @@ export function applyDiagramOperations(
 
             // Update the map with the new element
             cellMap.set(op.cell_id, importedNode)
-        } else if (op.type === "add") {
+        } else if (op.operation === "add") {
             // Check if ID already exists
             if (cellMap.has(op.cell_id)) {
                 errors.push({
@@ -632,7 +632,7 @@ export function applyDiagramOperations(
 
             // Add to map
             cellMap.set(op.cell_id, importedNode)
-        } else if (op.type === "delete") {
+        } else if (op.operation === "delete") {
             const existingCell = cellMap.get(op.cell_id)
             if (!existingCell) {
                 errors.push({

packages/mcp-server/package.json

@@ -1,6 +1,6 @@
 {
     "name": "@next-ai-drawio/mcp-server",
-    "version": "0.1.5",
+    "version": "0.1.6",
     "description": "MCP server for Next AI Draw.io - AI-powered diagram generation with real-time browser preview",
     "type": "module",
     "main": "dist/index.js",

packages/mcp-server/src/diagram-operations.ts

@@ -4,7 +4,7 @@
  */
 
 export interface DiagramOperation {
-    type: "update" | "add" | "delete"
+    operation: "update" | "add" | "delete"
     cell_id: string
     new_xml?: string
 }
@@ -77,7 +77,7 @@ export function applyDiagramOperations(
 
     // Process each operation
     for (const op of operations) {
-        if (op.type === "update") {
+        if (op.operation === "update") {
             const existingCell = cellMap.get(op.cell_id)
             if (!existingCell) {
                 errors.push({
@@ -129,7 +129,7 @@ export function applyDiagramOperations(
 
             // Update the map with the new element
             cellMap.set(op.cell_id, importedNode)
-        } else if (op.type === "add") {
+        } else if (op.operation === "add") {
             // Check if ID already exists
             if (cellMap.has(op.cell_id)) {
                 errors.push({
@@ -181,7 +181,7 @@ export function applyDiagramOperations(
 
             // Add to map
             cellMap.set(op.cell_id, importedNode)
-        } else if (op.type === "delete") {
+        } else if (op.operation === "delete") {
             const existingCell = cellMap.get(op.cell_id)
             if (!existingCell) {
                 errors.push({

packages/mcp-server/src/index.ts

@@ -265,14 +265,22 @@ server.registerTool(
             "- add: Add a new cell. Provide cell_id (new unique id) and new_xml.\n" +
             "- update: Replace an existing cell by its id. Provide cell_id and complete new_xml.\n" +
             "- delete: Remove a cell by its id. Only cell_id is needed.\n\n" +
-            "For add/update, new_xml must be a complete mxCell element including mxGeometry.",
+            "For add/update, new_xml must be a complete mxCell element including mxGeometry.\n\n" +
+            "Example - Add a rectangle:\n" +
+            '{"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' +
+            "Example - Update a cell:\n" +
+            '{"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' +
+            "Example - Delete a cell:\n" +
+            '{"operations": [{"operation": "delete", "cell_id": "rect-1"}]}',
         inputSchema: {
             operations: z
                 .array(
                     z.object({
-                        type: z
+                        operation: z
                             .enum(["update", "add", "delete"])
-                            .describe("Operation type"),
+                            .describe(
+                                "Operation to perform: add, update, or delete",
+                            ),
                         cell_id: z.string().describe("The id of the mxCell"),
                         new_xml: z
                             .string()
@@ -356,13 +364,13 @@ server.registerTool(
                     )
                     if (fixed) {
                         log.info(
-                            `Operation ${op.type} ${op.cell_id}: XML auto-fixed: ${fixes.join(", ")}`,
+                            `Operation ${op.operation} ${op.cell_id}: XML auto-fixed: ${fixes.join(", ")}`,
                         )
                         return { ...op, new_xml: fixed }
                     }
                     if (!valid && error) {
                         log.warn(
-                            `Operation ${op.type} ${op.cell_id}: XML validation failed: ${error}`,
+                            `Operation ${op.operation} ${op.cell_id}: XML validation failed: ${error}`,
                         )
                     }
                 }

scripts/test-diagram-operations.mjs

@@ -22,7 +22,7 @@ function applyDiagramOperations(xmlContent, operations) {
             result: xmlContent,
             errors: [
                 {
-                    type: "update",
+                    operation: "update",
                     cellId: "",
                     message: `XML parse error: ${parseError.textContent}`,
                 },
@@ -36,7 +36,7 @@ function applyDiagramOperations(xmlContent, operations) {
             result: xmlContent,
             errors: [
                 {
-                    type: "update",
+                    operation: "update",
                     cellId: "",
                     message: "Could not find <root> element in XML",
                 },
@@ -51,11 +51,11 @@ function applyDiagramOperations(xmlContent, operations) {
     })
 
     for (const op of operations) {
-        if (op.type === "update") {
+        if (op.operation === "update") {
             const existingCell = cellMap.get(op.cell_id)
             if (!existingCell) {
                 errors.push({
-                    type: "update",
+                    operation: "update",
                     cellId: op.cell_id,
                     message: `Cell with id="${op.cell_id}" not found`,
                 })
@@ -63,7 +63,7 @@ function applyDiagramOperations(xmlContent, operations) {
             }
             if (!op.new_xml) {
                 errors.push({
-                    type: "update",
+                    operation: "update",
                     cellId: op.cell_id,
                     message: "new_xml is required for update operation",
                 })
@@ -76,7 +76,7 @@ function applyDiagramOperations(xmlContent, operations) {
             const newCell = newDoc.querySelector("mxCell")
             if (!newCell) {
                 errors.push({
-                    type: "update",
+                    operation: "update",
                     cellId: op.cell_id,
                     message: "new_xml must contain an mxCell element",
                 })
@@ -85,7 +85,7 @@ function applyDiagramOperations(xmlContent, operations) {
             const newCellId = newCell.getAttribute("id")
             if (newCellId !== op.cell_id) {
                 errors.push({
-                    type: "update",
+                    operation: "update",
                     cellId: op.cell_id,
                     message: `ID mismatch: cell_id is "${op.cell_id}" but new_xml has id="${newCellId}"`,
                 })
@@ -94,10 +94,10 @@ function applyDiagramOperations(xmlContent, operations) {
             const importedNode = doc.importNode(newCell, true)
             existingCell.parentNode?.replaceChild(importedNode, existingCell)
             cellMap.set(op.cell_id, importedNode)
-        } else if (op.type === "add") {
+        } else if (op.operation === "add") {
             if (cellMap.has(op.cell_id)) {
                 errors.push({
-                    type: "add",
+                    operation: "add",
                     cellId: op.cell_id,
                     message: `Cell with id="${op.cell_id}" already exists`,
                 })
@@ -105,7 +105,7 @@ function applyDiagramOperations(xmlContent, operations) {
             }
             if (!op.new_xml) {
                 errors.push({
-                    type: "add",
+                    operation: "add",
                     cellId: op.cell_id,
                     message: "new_xml is required for add operation",
                 })
@@ -118,7 +118,7 @@ function applyDiagramOperations(xmlContent, operations) {
             const newCell = newDoc.querySelector("mxCell")
             if (!newCell) {
                 errors.push({
-                    type: "add",
+                    operation: "add",
                     cellId: op.cell_id,
                     message: "new_xml must contain an mxCell element",
                 })
@@ -127,7 +127,7 @@ function applyDiagramOperations(xmlContent, operations) {
             const newCellId = newCell.getAttribute("id")
             if (newCellId !== op.cell_id) {
                 errors.push({
-                    type: "add",
+                    operation: "add",
                     cellId: op.cell_id,
                     message: `ID mismatch: cell_id is "${op.cell_id}" but new_xml has id="${newCellId}"`,
                 })
@@ -136,11 +136,11 @@ function applyDiagramOperations(xmlContent, operations) {
             const importedNode = doc.importNode(newCell, true)
             root.appendChild(importedNode)
             cellMap.set(op.cell_id, importedNode)
-        } else if (op.type === "delete") {
+        } else if (op.operation === "delete") {
             const existingCell = cellMap.get(op.cell_id)
             if (!existingCell) {
                 errors.push({
-                    type: "delete",
+                    operation: "delete",
                     cellId: op.cell_id,
                     message: `Cell with id="${op.cell_id}" not found`,
                 })
@@ -201,7 +201,7 @@ function assert(condition, message) {
 test("Update operation changes cell value", () => {
     const { result, errors } = applyDiagramOperations(sampleXml, [
         {
-            type: "update",
+            operation: "update",
             cell_id: "2",
             new_xml:
                 '<mxCell id="2" value="Updated Box A" style="rounded=1;" vertex="1" parent="1"><mxGeometry x="100" y="100" width="120" height="60" as="geometry"/></mxCell>',
@@ -224,7 +224,7 @@ test("Update operation changes cell value", () => {
 test("Update operation fails for non-existent cell", () => {
     const { errors } = applyDiagramOperations(sampleXml, [
         {
-            type: "update",
+            operation: "update",
             cell_id: "999",
             new_xml: '<mxCell id="999" value="Test"/>',
         },
@@ -239,7 +239,7 @@ test("Update operation fails for non-existent cell", () => {
 test("Update operation fails on ID mismatch", () => {
     const { errors } = applyDiagramOperations(sampleXml, [
         {
-            type: "update",
+            operation: "update",
             cell_id: "2",
             new_xml: '<mxCell id="WRONG" value="Test"/>',
         },
@@ -254,7 +254,7 @@ test("Update operation fails on ID mismatch", () => {
 test("Add operation creates new cell", () => {
     const { result, errors } = applyDiagramOperations(sampleXml, [
         {
-            type: "add",
+            operation: "add",
             cell_id: "new1",
             new_xml:
                 '<mxCell id="new1" value="New Box" style="rounded=1;" vertex="1" parent="1"><mxGeometry x="500" y="100" width="120" height="60" as="geometry"/></mxCell>',
@@ -274,7 +274,7 @@ test("Add operation creates new cell", () => {
 test("Add operation fails for duplicate ID", () => {
     const { errors } = applyDiagramOperations(sampleXml, [
         {
-            type: "add",
+            operation: "add",
             cell_id: "2",
             new_xml: '<mxCell id="2" value="Duplicate"/>',
         },
@@ -289,7 +289,7 @@ test("Add operation fails for duplicate ID", () => {
 test("Add operation fails on ID mismatch", () => {
     const { errors } = applyDiagramOperations(sampleXml, [
         {
-            type: "add",
+            operation: "add",
             cell_id: "new1",
             new_xml: '<mxCell id="WRONG" value="Test"/>',
         },
@@ -303,7 +303,7 @@ test("Add operation fails on ID mismatch", () => {
 
 test("Delete operation removes cell", () => {
     const { result, errors } = applyDiagramOperations(sampleXml, [
-        { type: "delete", cell_id: "3" },
+        { operation: "delete", cell_id: "3" },
     ])
     assert(
         errors.length === 0,
@@ -315,7 +315,7 @@ test("Delete operation removes cell", () => {
 
 test("Delete operation fails for non-existent cell", () => {
     const { errors } = applyDiagramOperations(sampleXml, [
-        { type: "delete", cell_id: "999" },
+        { operation: "delete", cell_id: "999" },
     ])
     assert(errors.length === 1, "Should have one error")
     assert(
@@ -327,18 +327,18 @@ test("Delete operation fails for non-existent cell", () => {
 test("Multiple operations in sequence", () => {
     const { result, errors } = applyDiagramOperations(sampleXml, [
         {
-            type: "update",
+            operation: "update",
             cell_id: "2",
             new_xml:
                 '<mxCell id="2" value="Updated" style="rounded=1;" vertex="1" parent="1"><mxGeometry x="100" y="100" width="120" height="60" as="geometry"/></mxCell>',
         },
         {
-            type: "add",
+            operation: "add",
             cell_id: "new1",
             new_xml:
                 '<mxCell id="new1" value="Added" style="rounded=1;" vertex="1" parent="1"><mxGeometry x="500" y="100" width="120" height="60" as="geometry"/></mxCell>',
         },
-        { type: "delete", cell_id: "3" },
+        { operation: "delete", cell_id: "3" },
     ])
     assert(
         errors.length === 0,
@@ -354,14 +354,14 @@ test("Multiple operations in sequence", () => {
 
 test("Invalid XML returns parse error", () => {
     const { errors } = applyDiagramOperations("<not valid xml", [
-        { type: "delete", cell_id: "1" },
+        { operation: "delete", cell_id: "1" },
     ])
     assert(errors.length === 1, "Should have one error")
 })
 
 test("Missing root element returns error", () => {
     const { errors } = applyDiagramOperations("<mxfile></mxfile>", [
-        { type: "delete", cell_id: "1" },
+        { operation: "delete", cell_id: "1" },
     ])
     assert(errors.length === 1, "Should have one error")
     assert(