Add the code node to the workflow builder

Expose the workflow code node in the builder UI: a draggable palette entry, a
canvas node, and a config panel for the code, inputs, output variable, timeout,
and an optional JSON schema (validated before save). The panel serializes to the
same config the engine reads, so a code node built in the UI runs and produces an
artifact reference; workflows without code nodes load unchanged.

frontend/src/agents/types/workflow.ts

@@ -4,7 +4,17 @@ export type NodeType =
   | 'agent'
   | 'note'
   | 'state'
-  | 'condition';
+  | 'condition'
+  | 'code';
+
+export interface CodeNodeConfig {
+  code: string;
+  language: string;
+  inputs: string[];
+  output_variable?: string;
+  timeout?: number;
+  json_schema?: Record<string, unknown>;
+}
 
 export interface ConditionCase {
   name?: string;

frontend/src/agents/workflow/WorkflowBuilder.tsx

@@ -3,6 +3,7 @@ import 'reactflow/dist/style.css';
 import {
   AlertCircle,
   Bot,
+  Code2,
   Database,
   Flag,
   GitBranch,
@@ -64,10 +65,20 @@ import { getToolDisplayName } from '../../utils/toolUtils';
 import AgentPageHeader from '../AgentPageHeader';
 import { Agent } from '../types';
 import { ConditionCase, WorkflowNode } from '../types/workflow';
+import {
+  createDefaultCodeConfig,
+  normalizeCodeConfig,
+  parseCodeInputs,
+  parseCodeJsonSchemaDraft,
+  serializeCodeConfig,
+  stringifyCodeInputs,
+  validateCodeJsonSchema,
+} from './codeNodeConfig';
 import MobileBlocker from './components/MobileBlocker';
 import PromptTextArea from './components/PromptTextArea';
 import {
   AgentNode,
+  CodeNode,
   ConditionNode,
   EndNode,
   NoteNode,
@@ -283,15 +294,18 @@ function createWorkflowPayload(
         | 'agent'
         | 'note'
         | 'state'
-        | 'condition',
+        | 'condition'
+        | 'code',
       title: node.data.title || node.data.label || node.type,
       position: node.position,
       data:
-        node.type === 'agent' ||
-        node.type === 'condition' ||
-        node.type === 'state'
-          ? node.data.config
-          : node.data,
+        node.type === 'code'
+          ? serializeCodeConfig(node.data.config)
+          : node.type === 'agent' ||
+              node.type === 'condition' ||
+              node.type === 'state'
+            ? node.data.config
+            : node.data,
     })),
     edges: workflowEdges.map((edge) => ({
       id: edge.id,
@@ -310,6 +324,7 @@ const NODE_TYPES: NodeTypes = {
   note: NoteNode,
   state: SetStateNode,
   condition: ConditionNode,
+  code: CodeNode,
 };
 
 function WorkflowBuilderInner() {
@@ -515,6 +530,10 @@ function WorkflowBuilderInner() {
           mode: 'simple',
           cases: [{ name: '', expression: '', sourceHandle: 'case_0' }],
         };
+      } else if (type === 'code') {
+        baseNode.data.title = 'Code';
+        baseNode.data.label = 'Code';
+        baseNode.data.config = createDefaultCodeConfig();
       } else if (type === 'note') {
         baseNode.data.title = 'Note';
         baseNode.data.label = 'Note';
@@ -615,6 +634,27 @@ function WorkflowBuilderInner() {
     [handleUpdateNodeData, selectedNode],
   );
 
+  const handleCodeJsonSchemaChange = useCallback(
+    (text: string) => {
+      if (!selectedNode || selectedNode.type !== 'code') return;
+
+      const nodeId = selectedNode.id;
+      setAgentJsonSchemaDrafts((prev) => ({ ...prev, [nodeId]: text }));
+
+      const { schema, error } = parseCodeJsonSchemaDraft(text);
+      setAgentJsonSchemaErrors((prev) => ({ ...prev, [nodeId]: error }));
+      if (!error) {
+        handleUpdateNodeData({
+          config: {
+            ...(selectedNode.data.config || {}),
+            json_schema: schema,
+          },
+        });
+      }
+    },
+    [handleUpdateNodeData, selectedNode],
+  );
+
   const handleUpload = useCallback((files: File[]) => {
     if (files && files.length > 0) {
       setImageFile(files[0]);
@@ -781,6 +821,29 @@ function WorkflowBuilderInner() {
     });
   }, [selectedNode]);
 
+  useEffect(() => {
+    if (!selectedNode || selectedNode.type !== 'code') return;
+    const nodeId = selectedNode.id;
+    const rawSchema = selectedNode.data.config?.json_schema;
+
+    setAgentJsonSchemaDrafts((prev) => {
+      if (prev[nodeId] !== undefined) return prev;
+      if (rawSchema === undefined || rawSchema === null) {
+        return { ...prev, [nodeId]: '' };
+      }
+      try {
+        return { ...prev, [nodeId]: JSON.stringify(rawSchema, null, 2) };
+      } catch {
+        return { ...prev, [nodeId]: String(rawSchema) };
+      }
+    });
+
+    setAgentJsonSchemaErrors((prev) => {
+      if (prev[nodeId] !== undefined) return prev;
+      return { ...prev, [nodeId]: validateCodeJsonSchema(rawSchema) };
+    });
+  }, [selectedNode]);
+
   useEffect(() => {
     const loadAgentDetails = async () => {
       if (!agentId) return;
@@ -834,6 +897,10 @@ function WorkflowBuilderInner() {
             };
           } else if (n.type === 'state' && n.data) {
             nodeData.config = n.data;
+          } else if (n.type === 'code') {
+            nodeData.config = normalizeCodeConfig(
+              n.data as Record<string, unknown> | undefined,
+            );
           } else if (n.data) {
             Object.assign(nodeData, n.data);
           }
@@ -1089,6 +1156,27 @@ function WorkflowBuilderInner() {
       });
     });
 
+    const codeNodes = nodes.filter((n) => n.type === 'code');
+    codeNodes.forEach((node) => {
+      const codeTitle = node.data?.title || node.id;
+      const config = node.data?.config;
+      if (!(config?.code || '').trim()) {
+        errors.push(`Code node "${codeTitle}" must have code to run`);
+      }
+
+      const schemaValidationError = validateCodeJsonSchema(config?.json_schema);
+      const draftSchemaError = agentJsonSchemaErrors[node.id];
+      const effectiveSchemaError =
+        draftSchemaError !== undefined
+          ? draftSchemaError
+          : schemaValidationError;
+      if (effectiveSchemaError) {
+        errors.push(
+          `Code node "${codeTitle}" JSON schema ${effectiveSchemaError}`,
+        );
+      }
+    });
+
     return errors;
   }, [workflowName, nodes, edges, agentJsonSchemaErrors, availableModels]);
 
@@ -1367,6 +1455,31 @@ function WorkflowBuilderInner() {
     return selectedModel.supports_structured_output;
   }, [selectedNode, availableModels]);
 
+  const selectedCodeJsonSchemaText = useMemo(() => {
+    if (!selectedNode || selectedNode.type !== 'code') return '';
+
+    const draft = agentJsonSchemaDrafts[selectedNode.id];
+    if (draft !== undefined) return draft;
+
+    const schema = selectedNode.data.config?.json_schema;
+    if (schema === undefined || schema === null) return '';
+
+    try {
+      return JSON.stringify(schema, null, 2);
+    } catch {
+      return String(schema);
+    }
+  }, [selectedNode, agentJsonSchemaDrafts]);
+
+  const selectedCodeJsonSchemaError = useMemo(() => {
+    if (!selectedNode || selectedNode.type !== 'code') return null;
+
+    const cachedError = agentJsonSchemaErrors[selectedNode.id];
+    if (cachedError !== undefined) return cachedError;
+
+    return validateCodeJsonSchema(selectedNode.data.config?.json_schema);
+  }, [selectedNode, agentJsonSchemaErrors]);
+
   return (
     <>
       <MobileBlocker />
@@ -1724,6 +1837,23 @@ function WorkflowBuilderInner() {
                     </span>
                   </div>
                 </div>
+                <div
+                  className="group border-border bg-card flex cursor-move items-center gap-3 rounded-full border px-4 py-3 shadow-sm transition-all hover:shadow-md"
+                  draggable
+                  onDragStart={(e) => handleNodeDragStart(e, 'code')}
+                >
+                  <div className="flex h-8 w-8 shrink-0 items-center justify-center rounded-full bg-indigo-100 text-indigo-600 transition-colors group-hover:bg-indigo-600 group-hover:text-white dark:bg-indigo-900/40 dark:text-indigo-300">
+                    <Code2 size={18} />
+                  </div>
+                  <div className="flex flex-col">
+                    <span className="text-foreground text-sm font-medium">
+                      Code
+                    </span>
+                    <span className="text-muted-foreground text-xs">
+                      Run code in a sandbox
+                    </span>
+                  </div>
+                </div>
               </div>
             </div>
           </div>
@@ -1765,6 +1895,7 @@ function WorkflowBuilderInner() {
                       {selectedNode.type === 'note' && 'Note'}
                       {selectedNode.type === 'state' && 'Set global variables'}
                       {selectedNode.type === 'condition' && 'If / Else'}
+                      {selectedNode.type === 'code' && 'Code'}
                     </h3>
                     <Button
                       type="button"
@@ -2592,6 +2723,148 @@ function WorkflowBuilderInner() {
                                 </Button>
                               </>
                             )}
+
+                            {selectedNode.type === 'code' && (
+                              <>
+                                <p className="text-xs text-gray-500 dark:text-gray-400">
+                                  Run code in the workflow sandbox. Produced
+                                  files are saved as artifacts.
+                                </p>
+                                <div>
+                                  <label className="mb-2 block text-sm font-medium text-gray-700 dark:text-gray-300">
+                                    Code
+                                  </label>
+                                  <textarea
+                                    value={selectedNode.data.config?.code ?? ''}
+                                    onChange={(e) =>
+                                      handleUpdateNodeData({
+                                        config: {
+                                          ...(selectedNode.data.config || {}),
+                                          code: e.target.value,
+                                        },
+                                      })
+                                    }
+                                    className="border-border focus-visible:ring-ring/50 focus-visible:border-ring bg-card w-full rounded-xl border px-3 py-2 font-mono text-xs transition-all outline-none focus-visible:ring-2 dark:text-white"
+                                    rows={10}
+                                    spellCheck={false}
+                                    placeholder={'print("hello world")'}
+                                  />
+                                </div>
+                                <div>
+                                  <label className="mb-2 block text-sm font-medium text-gray-700 dark:text-gray-300">
+                                    Inputs
+                                  </label>
+                                  <textarea
+                                    value={stringifyCodeInputs(
+                                      selectedNode.data.config?.inputs,
+                                    )}
+                                    onChange={(e) =>
+                                      handleUpdateNodeData({
+                                        config: {
+                                          ...(selectedNode.data.config || {}),
+                                          inputs: parseCodeInputs(
+                                            e.target.value,
+                                          ),
+                                        },
+                                      })
+                                    }
+                                    className="border-border focus-visible:ring-ring/50 focus-visible:border-ring bg-card w-full rounded-xl border px-3 py-2 text-sm transition-all outline-none focus-visible:ring-2 dark:text-white"
+                                    rows={2}
+                                    placeholder="One per line: state variable or artifact ref"
+                                  />
+                                  <p className="text-muted-foreground mt-1 text-xs">
+                                    Artifact refs or state-variable names, one
+                                    per line.
+                                  </p>
+                                </div>
+                                <div>
+                                  <label className="mb-2 block text-sm font-medium text-gray-700 dark:text-gray-300">
+                                    Output Variable
+                                  </label>
+                                  <Input
+                                    type="text"
+                                    value={
+                                      selectedNode.data.config
+                                        ?.output_variable || ''
+                                    }
+                                    onChange={(e) =>
+                                      handleUpdateNodeData({
+                                        config: {
+                                          ...(selectedNode.data.config || {}),
+                                          output_variable: e.target.value,
+                                        },
+                                      })
+                                    }
+                                    className="bg-card h-auto rounded-xl px-3 py-2 text-sm shadow-none"
+                                    placeholder="Variable name for output"
+                                  />
+                                </div>
+                                <div>
+                                  <label className="mb-2 block text-sm font-medium text-gray-700 dark:text-gray-300">
+                                    Timeout (seconds)
+                                  </label>
+                                  <Input
+                                    type="number"
+                                    min={1}
+                                    value={
+                                      selectedNode.data.config?.timeout ?? ''
+                                    }
+                                    onChange={(e) => {
+                                      const raw = e.target.value;
+                                      const parsed =
+                                        raw.trim() === ''
+                                          ? undefined
+                                          : Number.parseInt(raw, 10);
+                                      handleUpdateNodeData({
+                                        config: {
+                                          ...(selectedNode.data.config || {}),
+                                          timeout:
+                                            parsed !== undefined &&
+                                            Number.isFinite(parsed)
+                                              ? parsed
+                                              : undefined,
+                                        },
+                                      });
+                                    }}
+                                    className="bg-card h-auto rounded-xl px-3 py-2 text-sm shadow-none"
+                                    placeholder="Optional"
+                                  />
+                                </div>
+                                <div>
+                                  <label className="mb-2 block text-sm font-medium text-gray-700 dark:text-gray-300">
+                                    Structured Output (JSON Schema)
+                                  </label>
+                                  <textarea
+                                    value={selectedCodeJsonSchemaText}
+                                    onChange={(e) =>
+                                      handleCodeJsonSchemaChange(e.target.value)
+                                    }
+                                    className="border-border focus-visible:ring-ring/50 focus-visible:border-ring bg-card w-full rounded-xl border px-3 py-2 font-mono text-xs transition-all outline-none focus-visible:ring-2 dark:text-white"
+                                    rows={6}
+                                    placeholder={`{
+  "type": "object",
+  "properties": {
+    "result": { "type": "string" }
+  },
+  "required": ["result"]
+}`}
+                                  />
+                                  {selectedCodeJsonSchemaText.trim() !== '' && (
+                                    <p
+                                      className={`mt-2 text-xs ${
+                                        selectedCodeJsonSchemaError
+                                          ? 'text-red-600 dark:text-red-400'
+                                          : 'text-green-600 dark:text-green-400'
+                                      }`}
+                                    >
+                                      {selectedCodeJsonSchemaError
+                                        ? `Invalid JSON schema: ${selectedCodeJsonSchemaError}`
+                                        : 'Valid JSON schema'}
+                                    </p>
+                                  )}
+                                </div>
+                              </>
+                            )}
                           </>
                         )}
                     </div>
@@ -2629,10 +2902,20 @@ function WorkflowBuilderInner() {
                   .filter((n) => n.type !== 'note')
                   .map((n) => ({
                     id: n.id,
-                    type: n.type as 'start' | 'end' | 'agent' | 'state',
+                    type: n.type as
+                      | 'start'
+                      | 'end'
+                      | 'agent'
+                      | 'state'
+                      | 'code',
                     title: n.data.title || n.data.label || n.type,
                     position: n.position,
-                    data: n.type === 'agent' ? n.data.config : n.data,
+                    data:
+                      n.type === 'code'
+                        ? serializeCodeConfig(n.data.config)
+                        : n.type === 'agent'
+                          ? n.data.config
+                          : n.data,
                   })),
                 edges: edges.map((e) => ({
                   id: e.id,

frontend/src/agents/workflow/WorkflowPreview.tsx

@@ -2,6 +2,7 @@ import {
   Bot,
   CheckCircle2,
   Circle,
+  Code2,
   Database,
   Flag,
   GitBranch,
@@ -56,6 +57,7 @@ const NODE_ICONS: Record<string, React.ReactNode> = {
   note: <StickyNote className="h-3 w-3" />,
   state: <Database className="h-3 w-3" />,
   condition: <GitBranch className="h-3 w-3" />,
+  code: <Code2 className="h-3 w-3" />,
 };
 
 const NODE_COLORS: Record<string, string> = {
@@ -65,6 +67,7 @@ const NODE_COLORS: Record<string, string> = {
   note: 'text-yellow-600 dark:text-yellow-400',
   state: 'text-blue-600 dark:text-blue-400',
   condition: 'text-orange-600 dark:text-orange-400',
+  code: 'text-indigo-600 dark:text-indigo-400',
 };
 
 function ExecutionDetails({

frontend/src/agents/workflow/codeNodeConfig.test.ts

@@ -0,0 +1,173 @@
+import { describe, expect, it } from 'vitest';
+
+import {
+  createDefaultCodeConfig,
+  normalizeCodeConfig,
+  parseCodeInputs,
+  parseCodeJsonSchemaDraft,
+  serializeCodeConfig,
+  stringifyCodeInputs,
+  validateCodeJsonSchema,
+} from './codeNodeConfig';
+
+describe('validateCodeJsonSchema', () => {
+  it('treats undefined/null as valid (no schema)', () => {
+    expect(validateCodeJsonSchema(undefined)).toBeNull();
+    expect(validateCodeJsonSchema(null)).toBeNull();
+  });
+
+  it('rejects arrays and non-objects', () => {
+    expect(validateCodeJsonSchema([])).toMatch(/valid JSON object/);
+    expect(validateCodeJsonSchema('x')).toMatch(/valid JSON object/);
+  });
+
+  it('requires a type or schema field', () => {
+    expect(validateCodeJsonSchema({})).toMatch(/"type" or "schema"/);
+    expect(validateCodeJsonSchema({ type: 'object' })).toBeNull();
+    expect(validateCodeJsonSchema({ schema: {} })).toBeNull();
+  });
+});
+
+describe('parseCodeJsonSchemaDraft', () => {
+  it('returns undefined schema and no error for blank input', () => {
+    expect(parseCodeJsonSchemaDraft('   ')).toEqual({
+      schema: undefined,
+      error: null,
+    });
+  });
+
+  it('flags invalid JSON', () => {
+    const result = parseCodeJsonSchemaDraft('{ not json');
+    expect(result.schema).toBeUndefined();
+    expect(result.error).toMatch(/valid JSON/);
+  });
+
+  it('flags structurally invalid schema', () => {
+    const result = parseCodeJsonSchemaDraft('{"foo": 1}');
+    expect(result.schema).toBeUndefined();
+    expect(result.error).toMatch(/"type" or "schema"/);
+  });
+
+  it('parses a valid schema', () => {
+    const result = parseCodeJsonSchemaDraft(
+      '{"type":"object","properties":{}}',
+    );
+    expect(result.error).toBeNull();
+    expect(result.schema).toEqual({ type: 'object', properties: {} });
+  });
+});
+
+describe('inputs (de)serialization', () => {
+  it('splits on newlines and commas and trims', () => {
+    expect(parseCodeInputs('A1\nfoo, bar\n\n  baz  ')).toEqual([
+      'A1',
+      'foo',
+      'bar',
+      'baz',
+    ]);
+  });
+
+  it('round-trips through stringify', () => {
+    const inputs = ['A1', 'state_var'];
+    expect(parseCodeInputs(stringifyCodeInputs(inputs))).toEqual(inputs);
+  });
+
+  it('stringifies undefined to empty string', () => {
+    expect(stringifyCodeInputs(undefined)).toBe('');
+  });
+});
+
+describe('createDefaultCodeConfig', () => {
+  it('returns python defaults with empty code and inputs', () => {
+    expect(createDefaultCodeConfig()).toEqual({
+      code: '',
+      language: 'python',
+      inputs: [],
+    });
+  });
+});
+
+describe('serializeCodeConfig', () => {
+  it('omits optional fields when empty', () => {
+    const serialized = serializeCodeConfig({
+      code: 'print(1)',
+      language: 'python',
+      inputs: ['', '  '],
+      output_variable: '   ',
+    });
+    expect(serialized).toEqual({
+      code: 'print(1)',
+      language: 'python',
+      inputs: [],
+    });
+    expect('output_variable' in serialized).toBe(false);
+    expect('timeout' in serialized).toBe(false);
+    expect('json_schema' in serialized).toBe(false);
+  });
+
+  it('keeps all CodeNodeConfig fields when present', () => {
+    const serialized = serializeCodeConfig({
+      code: 'print(1)',
+      language: 'python',
+      inputs: ['A1', 'state_var'],
+      output_variable: 'result',
+      timeout: 30,
+      json_schema: { type: 'object' },
+    });
+    expect(serialized).toEqual({
+      code: 'print(1)',
+      language: 'python',
+      inputs: ['A1', 'state_var'],
+      output_variable: 'result',
+      timeout: 30,
+      json_schema: { type: 'object' },
+    });
+  });
+
+  it('falls back to python defaults for an undefined config', () => {
+    expect(serializeCodeConfig(undefined)).toEqual({
+      code: '',
+      language: 'python',
+      inputs: [],
+    });
+  });
+});
+
+describe('normalizeCodeConfig', () => {
+  it('tolerates a missing/empty payload', () => {
+    expect(normalizeCodeConfig(undefined)).toEqual({
+      code: '',
+      language: 'python',
+      inputs: [],
+    });
+  });
+
+  it('coerces bad field types without throwing', () => {
+    const config = normalizeCodeConfig({
+      code: 42,
+      language: '',
+      inputs: ['A1', 5, 'B2'],
+      output_variable: '',
+      timeout: 'soon',
+      json_schema: [],
+    } as unknown as Record<string, unknown>);
+    expect(config).toEqual({
+      code: '',
+      language: 'python',
+      inputs: ['A1', 'B2'],
+    });
+  });
+
+  it('preserves a fully populated saved config (round-trip with serialize)', () => {
+    const saved = {
+      code: 'print(1)',
+      language: 'python',
+      inputs: ['A1'],
+      output_variable: 'result',
+      timeout: 30,
+      json_schema: { type: 'object' },
+    };
+    const normalized = normalizeCodeConfig(saved);
+    expect(serializeCodeConfig(normalized)).toEqual(saved);
+  });
+});

frontend/src/agents/workflow/codeNodeConfig.ts

@@ -0,0 +1,133 @@
+import type { CodeNodeConfig } from '../types/workflow';
+
+const DEFAULT_LANGUAGE = 'python';
+
+/**
+ * Validate a parsed JSON schema object the same way the agent node does:
+ * it must be a non-array object that declares a "type" or "schema" field.
+ * Returns null when valid (or absent), otherwise a short error fragment.
+ */
+export function validateCodeJsonSchema(schema: unknown): string | null {
+  if (schema === undefined || schema === null) return null;
+  if (typeof schema !== 'object' || Array.isArray(schema)) {
+    return 'must be a valid JSON object';
+  }
+  const schemaObject = schema as Record<string, unknown>;
+  if (!('schema' in schemaObject) && !('type' in schemaObject)) {
+    return 'must include either a "type" or "schema" field';
+  }
+  return null;
+}
+
+/**
+ * Parse the raw json_schema textarea content. Returns the parsed schema (or
+ * undefined when blank) and a validation error message when invalid.
+ */
+export function parseCodeJsonSchemaDraft(text: string): {
+  schema: Record<string, unknown> | undefined;
+  error: string | null;
+} {
+  if (text.trim() === '') {
+    return { schema: undefined, error: null };
+  }
+  let parsed: unknown;
+  try {
+    parsed = JSON.parse(text);
+  } catch {
+    return { schema: undefined, error: 'must be valid JSON' };
+  }
+  const error = validateCodeJsonSchema(parsed);
+  if (error) {
+    return { schema: undefined, error };
+  }
+  return { schema: parsed as Record<string, unknown>, error: null };
+}
+
+/** Split a newline/comma separated inputs textarea into a clean ref list. */
+export function parseCodeInputs(text: string): string[] {
+  return text
+    .split(/[\n,]/)
+    .map((entry) => entry.trim())
+    .filter((entry) => entry.length > 0);
+}
+
+/** Render an inputs list back into the textarea (one ref per line). */
+export function stringifyCodeInputs(inputs: string[] | undefined): string {
+  return (inputs || []).join('\n');
+}
+
+/** Default config applied when a fresh code node is dropped onto the canvas. */
+export function createDefaultCodeConfig(): CodeNodeConfig {
+  return {
+    code: '',
+    language: DEFAULT_LANGUAGE,
+    inputs: [],
+  };
+}
+
+/**
+ * Normalize an arbitrary loaded config (from a saved workflow) into the editor
+ * shape, tolerating missing/extra fields so existing workflows keep loading.
+ */
+export function normalizeCodeConfig(
+  raw: Record<string, unknown> | undefined,
+): CodeNodeConfig {
+  const source = raw || {};
+  const config: CodeNodeConfig = {
+    code: typeof source.code === 'string' ? source.code : '',
+    language:
+      typeof source.language === 'string' && source.language.trim() !== ''
+        ? source.language
+        : DEFAULT_LANGUAGE,
+    inputs: Array.isArray(source.inputs)
+      ? source.inputs.filter(
+          (entry): entry is string => typeof entry === 'string',
+        )
+      : [],
+  };
+  if (typeof source.output_variable === 'string' && source.output_variable) {
+    config.output_variable = source.output_variable;
+  }
+  if (typeof source.timeout === 'number' && Number.isFinite(source.timeout)) {
+    config.timeout = source.timeout;
+  }
+  if (
+    source.json_schema &&
+    typeof source.json_schema === 'object' &&
+    !Array.isArray(source.json_schema)
+  ) {
+    config.json_schema = source.json_schema as Record<string, unknown>;
+  }
+  return config;
+}
+
+/**
+ * Serialize the editor config into the exact CodeNodeConfig shape the backend
+ * expects. Optional fields are omitted when empty so the payload stays clean.
+ */
+export function serializeCodeConfig(
+  config: CodeNodeConfig | undefined,
+): CodeNodeConfig {
+  const source = config || createDefaultCodeConfig();
+  const serialized: CodeNodeConfig = {
+    code: source.code || '',
+    language: source.language || DEFAULT_LANGUAGE,
+    inputs: (source.inputs || []).filter(
+      (entry) => typeof entry === 'string' && entry.trim() !== '',
+    ),
+  };
+  if (source.output_variable && source.output_variable.trim() !== '') {
+    serialized.output_variable = source.output_variable.trim();
+  }
+  if (typeof source.timeout === 'number' && Number.isFinite(source.timeout)) {
+    serialized.timeout = source.timeout;
+  }
+  if (
+    source.json_schema &&
+    typeof source.json_schema === 'object' &&
+    !Array.isArray(source.json_schema)
+  ) {
+    serialized.json_schema = source.json_schema;
+  }
+  return serialized;
+}

frontend/src/agents/workflow/nodes/BaseNode.tsx

@@ -5,7 +5,7 @@ interface BaseNodeProps {
   title: string;
   children?: ReactNode;
   selected?: boolean;
-  type?: 'start' | 'end' | 'default' | 'state' | 'agent' | 'condition';
+  type?: 'start' | 'end' | 'default' | 'state' | 'agent' | 'condition' | 'code';
   icon?: ReactNode;
   handles?: {
     source?: boolean;
@@ -42,6 +42,9 @@ export const BaseNode: React.FC<BaseNodeProps> = ({
   } else if (type === 'condition') {
     iconBg = 'bg-orange-100 dark:bg-orange-900/30';
     iconColor = 'text-orange-600 dark:text-orange-400';
+  } else if (type === 'code') {
+    iconBg = 'bg-indigo-100 dark:bg-indigo-900/30';
+    iconColor = 'text-indigo-600 dark:text-indigo-400';
   }
 
   return (

frontend/src/agents/workflow/nodes/CodeNode.tsx

@@ -0,0 +1,56 @@
+import { Code2 } from 'lucide-react';
+import { memo } from 'react';
+import { NodeProps } from 'reactflow';
+
+import { CodeNodeConfig } from '../../types/workflow';
+import { BaseNode } from './BaseNode';
+
+type CodeNodeData = {
+  title?: string;
+  label?: string;
+  config?: Partial<CodeNodeConfig>;
+};
+
+const CodeNode = ({ data, selected }: NodeProps<CodeNodeData>) => {
+  const title = data.title || data.label || 'Code';
+  const config = data.config || {};
+  const code = (config.code || '').trim();
+  const firstLine = code.split('\n').find((line) => line.trim() !== '') || '';
+  const codeHint =
+    firstLine.length > 40 ? `${firstLine.slice(0, 40)}…` : firstLine;
+
+  return (
+    <BaseNode
+      title={title}
+      type="code"
+      selected={selected}
+      icon={<Code2 size={16} />}
+      handles={{ source: true, target: true }}
+    >
+      <div className="flex flex-col gap-1">
+        {codeHint ? (
+          <div
+            className="truncate font-mono text-xs text-gray-500 dark:text-gray-400"
+            title={code}
+          >
+            {codeHint}
+          </div>
+        ) : (
+          <div className="text-xs text-gray-500 dark:text-gray-400">
+            No code yet
+          </div>
+        )}
+        {config.output_variable && (
+          <div
+            className="truncate text-xs text-gray-500 dark:text-gray-400"
+            title={`Output: ${config.output_variable}`}
+          >
+            Output: {config.output_variable}
+          </div>
+        )}
+      </div>
+    </BaseNode>
+  );
+};
+
+export default memo(CodeNode);

frontend/src/agents/workflow/nodes/index.tsx

@@ -2,6 +2,7 @@ import { Bot, Flag, Play, StickyNote } from 'lucide-react';
 import { memo } from 'react';
 
 import { BaseNode } from './BaseNode';
+import CodeNode from './CodeNode';
 import ConditionNode from './ConditionNode';
 import SetStateNode from './SetStateNode';
 
@@ -145,3 +146,4 @@ export const NoteNode = memo(function NoteNode({
 
 export { SetStateNode };
 export { ConditionNode };
+export { CodeNode };