diff --git a/src/workflows/NodeInspector.jsx b/src/workflows/NodeInspector.jsx
new file mode 100644
index 0000000..22ec067
--- /dev/null
+++ b/src/workflows/NodeInspector.jsx
@@ -0,0 +1,65 @@
+import React from 'react'
+
+const CONDITION_OPERATIONS = ['equals', 'not_equals', 'exists', 'greater_than', 'less_than', 'contains', 'array_not_empty', 'score_at_least']
+
+export default function NodeInspector({ node, tools, onChange, onDelete, readOnly }) {
+  const [configText, setConfigText] = React.useState('{}')
+  const [configError, setConfigError] = React.useState('')
+
+  React.useEffect(() => {
+    setConfigText(JSON.stringify(node?.data?.config || {}, null, 2))
+    setConfigError('')
+  }, [node])
+
+  if (!node) return <div className="workflow-inspector empty">Select a node to edit it.</div>
+  const nodeType = node.data.nodeType
+  const patchConfig = (config) => onChange({ ...node, data: { ...node.data, config, tool: config.tool || '' } })
+  return (
+    <div className="workflow-inspector">
+      <div className="workflow-inspector-heading">
+        <strong>{node.id}</strong>
+        {!readOnly && <button type="button" className="button danger ghost" onClick={onDelete}>Delete</button>}
+      </div>
+      <label>Label
+        <input disabled={readOnly} value={node.data.label || ''} onChange={(event) => onChange({ ...node, data: { ...node.data, label: event.target.value } })} />
+      </label>
+      {nodeType === 'tool' && (
+        <label>Registered tool
+          <select
+            disabled={readOnly}
+            value={node.data.config?.tool || ''}
+            onChange={(event) => patchConfig({ ...node.data.config, tool: event.target.value, arguments: node.data.config?.arguments || {} })}
+          >
+            <option value="">Select a tool</option>
+            {tools.map(tool => <option key={tool.name} value={tool.name}>{tool.name}</option>)}
+          </select>
+        </label>
+      )}
+      {nodeType === 'condition' && (
+        <label>Operation
+          <select disabled={readOnly} value={node.data.config?.operation || 'equals'} onChange={(event) => patchConfig({ ...node.data.config, operation: event.target.value })}>
+            {CONDITION_OPERATIONS.map(operation => <option key={operation}>{operation}</option>)}
+          </select>
+        </label>
+      )}
+      <label>Configuration JSON
+        <textarea
+          rows={18}
+          disabled={readOnly}
+          value={configText}
+          onChange={(event) => {
+            const text = event.target.value
+            setConfigText(text)
+            try {
+              patchConfig(JSON.parse(text))
+              setConfigError('')
+            } catch (error) {
+              setConfigError(error.message)
+            }
+          }}
+        />
+      </label>
+      {configError && <p className="workflow-validation-error">{configError}</p>}
+    </div>
+  )
+}
diff --git a/src/workflows/NodePalette.jsx b/src/workflows/NodePalette.jsx
new file mode 100644
index 0000000..3916dfc
--- /dev/null
+++ b/src/workflows/NodePalette.jsx
@@ -0,0 +1,22 @@
+import React from 'react'
+
+export const NODE_TYPES = ['input', 'output', 'tool', 'prompt', 'agent', 'condition', 'merge', 'template', 'select', 'limit']
+
+export default function NodePalette({ onAdd }) {
+  return (
+    <div className="workflow-palette">
+      <strong>Nodes</strong>
+      {NODE_TYPES.map(type => (
+        <button
+          key={type}
+          type="button"
+          draggable
+          onDragStart={(event) => event.dataTransfer.setData('application/heimgeist-workflow-node', type)}
+          onClick={() => onAdd(type)}
+        >
+          {type}
+        </button>
+      ))}
+    </div>
+  )
+}
diff --git a/src/workflows/WorkflowCanvas.jsx b/src/workflows/WorkflowCanvas.jsx
new file mode 100644
index 0000000..13d3dc4
--- /dev/null
+++ b/src/workflows/WorkflowCanvas.jsx
@@ -0,0 +1,45 @@
+import React from 'react'
+import {
+  Background,
+  Controls,
+  MiniMap,
+  ReactFlow,
+  addEdge,
+  applyEdgeChanges,
+  applyNodeChanges,
+} from '@xyflow/react'
+import '@xyflow/react/dist/style.css'
+import WorkflowNode from './WorkflowNode'
+
+const nodeTypes = { workflow: WorkflowNode }
+
+export default function WorkflowCanvas({ edges, nodes, onEdgesChange, onNodesChange, onSelectNode, onDropNode }) {
+  const [instance, setInstance] = React.useState(null)
+  return (
+    <div className="workflow-canvas">
+      <ReactFlow
+        nodes={nodes}
+        edges={edges}
+        nodeTypes={nodeTypes}
+        onInit={setInstance}
+        onNodesChange={(changes) => onNodesChange(applyNodeChanges(changes, nodes))}
+        onEdgesChange={(changes) => onEdgesChange(applyEdgeChanges(changes, edges))}
+        onConnect={(connection) => onEdgesChange(addEdge({ ...connection, id: `${connection.source}-${connection.target}-${Date.now()}` }, edges))}
+        onNodeClick={(_event, node) => onSelectNode(node.id)}
+        onPaneClick={() => onSelectNode(null)}
+        onDragOver={(event) => { event.preventDefault(); event.dataTransfer.dropEffect = 'move' }}
+        onDrop={(event) => {
+          event.preventDefault()
+          const type = event.dataTransfer.getData('application/heimgeist-workflow-node')
+          if (!type || !instance) return
+          onDropNode(type, instance.screenToFlowPosition({ x: event.clientX, y: event.clientY }))
+        }}
+        fitView
+      >
+        <Background gap={20} />
+        <MiniMap pannable zoomable />
+        <Controls />
+      </ReactFlow>
+    </div>
+  )
+}
diff --git a/src/workflows/WorkflowEditor.jsx b/src/workflows/WorkflowEditor.jsx
new file mode 100644
index 0000000..8787853
--- /dev/null
+++ b/src/workflows/WorkflowEditor.jsx
@@ -0,0 +1,193 @@
+import React from 'react'
+import NodePalette from './NodePalette'
+import NodeInspector from './NodeInspector'
+import WorkflowCanvas from './WorkflowCanvas'
+import WorkflowRunInspector from './WorkflowRunInspector'
+import WorkflowValidationPanel from './WorkflowValidationPanel'
+import {
+  createWorkflowRun,
+  getWorkflowRun,
+  saveWorkflowRevision,
+  streamWorkflowEvents,
+  updateWorkflow,
+  validateWorkflow,
+} from './workflowApi'
+
+function toCanvasNode(node) {
+  return {
+    id: node.id,
+    type: 'workflow',
+    position: node.position || { x: 0, y: 0 },
+    data: {
+      nodeType: node.type,
+      label: node.config?.label || node.id,
+      config: node.config || {},
+      tool: node.config?.tool || '',
+    },
+  }
+}
+
+function toGraphNode(node) {
+  const config = { ...(node.data.config || {}) }
+  if (node.data.label && node.data.label !== node.id) config.label = node.data.label
+  return { id: node.id, type: node.data.nodeType, position: node.position, config }
+}
+
+function nextNodeConfig(type) {
+  if (type === 'tool') return { tool: '', arguments: {} }
+  if (type === 'prompt') return { model_source: 'chat_model', system_template: '', user_template: '{{input.prompt}}', output_mode: 'text', temperature: 0.2 }
+  if (type === 'agent') return { model: { $ref: 'run.chat_model' }, messages: { $ref: 'run.messages' }, allowed_tool_names: [], maximum_rounds: 4 }
+  if (type === 'condition') return { value: { $ref: 'input.prompt' }, operation: 'exists', compare_to: null }
+  if (type === 'merge') return { values: [], deduplicate_by: 'url' }
+  if (type === 'template') return { template: '{{input.prompt}}', values: {} }
+  if (type === 'select') return { value: { $ref: 'input.prompt' } }
+  if (type === 'limit') return { value: { $ref: 'input.prompt' }, maximum_chars: 12000 }
+  if (type === 'output') return { value: { content: { $ref: 'input.prompt' }, sources: [], usage: {} } }
+  return {}
+}
+
+export default function WorkflowEditor({ apiBase, model, onChanged, tools, workflow }) {
+  const [nodes, setNodes] = React.useState([])
+  const [edges, setEdges] = React.useState([])
+  const [selectedNodeId, setSelectedNodeId] = React.useState(null)
+  const [inputsText, setInputsText] = React.useState('{}')
+  const [outputsText, setOutputsText] = React.useState('{}')
+  const [limits, setLimits] = React.useState({})
+  const [metadata, setMetadata] = React.useState({ name: '', description: '', routing_description: '', routing_examples: [], enabled: true })
+  const [validation, setValidation] = React.useState(null)
+  const [status, setStatus] = React.useState('')
+  const [testPrompt, setTestPrompt] = React.useState('Summarize this sample request.')
+  const [testRun, setTestRun] = React.useState(null)
+  const [testEvents, setTestEvents] = React.useState([])
+
+  React.useEffect(() => {
+    const graph = workflow?.graph || {}
+    setNodes((graph.nodes || []).map(toCanvasNode))
+    setEdges(graph.edges || [])
+    setInputsText(JSON.stringify(graph.inputs || {}, null, 2))
+    setOutputsText(JSON.stringify(graph.outputs || {}, null, 2))
+    setLimits(graph.limits || {})
+    setMetadata({
+      name: workflow?.name || '', description: workflow?.description || '',
+      routing_description: workflow?.routing_description || '', routing_examples: workflow?.routing_examples || [],
+      enabled: workflow?.enabled !== false,
+    })
+    setSelectedNodeId(null)
+    setValidation(null)
+    setTestRun(null)
+    setTestEvents([])
+  }, [workflow])
+
+  const readOnly = Boolean(workflow?.built_in)
+  const selectedNode = nodes.find(node => node.id === selectedNodeId) || null
+  const buildGraph = () => ({
+    schema_version: 1,
+    inputs: JSON.parse(inputsText || '{}'),
+    outputs: JSON.parse(outputsText || '{}'),
+    nodes: nodes.map(toGraphNode),
+    edges: edges.map(edge => ({
+      id: edge.id, source: edge.source, source_handle: edge.sourceHandle || edge.source_handle || 'output',
+      target: edge.target, target_handle: edge.targetHandle || edge.target_handle || 'input',
+    })),
+    limits,
+  })
+
+  const addNode = (type, position = { x: 120 + nodes.length * 35, y: 120 + nodes.length * 20 }) => {
+    if (readOnly) return
+    const id = `${type}-${Date.now().toString(36)}`
+    setNodes(previous => [...previous, toCanvasNode({ id, type, position, config: nextNodeConfig(type) })])
+    setSelectedNodeId(id)
+  }
+
+  const runValidation = async () => {
+    try {
+      const result = await validateWorkflow(apiBase, buildGraph())
+      setValidation(result)
+      return result
+    } catch (error) {
+      setValidation({ valid: false, errors: [{ code: 'editor', message: error.message }] })
+      return null
+    }
+  }
+
+  const save = async () => {
+    const result = await runValidation()
+    if (!result?.valid) return
+    setStatus('Saving…')
+    try {
+      await updateWorkflow(apiBase, workflow.id, metadata)
+      await saveWorkflowRevision(apiBase, workflow.id, buildGraph())
+      setStatus('Saved as a new revision.')
+      await onChanged(workflow.id)
+    } catch (error) {
+      setStatus(error.message)
+    }
+  }
+
+  const test = async () => {
+    const result = await runValidation()
+    if (!result?.valid) return
+    setTestRun({ status: 'starting', node_runs: [] })
+    setTestEvents([])
+    try {
+      const created = await createWorkflowRun(apiBase, {
+        message: testPrompt, model, selection_mode: 'explicit', workflow_id: workflow.id,
+        sample_inputs: { prompt: testPrompt }, stream: true, explicit_user_action: true,
+      })
+      await streamWorkflowEvents(apiBase, created.run_id, {
+        onEvent: event => setTestEvents(previous => [...previous, event]),
+      })
+      setTestRun(await getWorkflowRun(apiBase, created.run_id))
+    } catch (error) {
+      setTestRun({ status: 'failed', error: { message: error.message }, node_runs: [] })
+    }
+  }
+
+  if (!workflow) return <div className="workflow-empty">Select a workflow.</div>
+  return (
+    <div className="workflow-editor">
+      <div className="workflow-editor-toolbar">
+        <input value={metadata.name} disabled={readOnly} onChange={(event) => setMetadata(value => ({ ...value, name: event.target.value }))} />
+        <button className="button ghost" type="button" onClick={runValidation}>Validate</button>
+        {!readOnly && <button className="button" type="button" onClick={save}>Save revision</button>}
+        {readOnly && <span className="header-subtle">Built-in revisions are read-only.</span>}
+        {status && <span className="header-subtle">{status}</span>}
+      </div>
+      <div className="workflow-editor-meta">
+        <label>Description<textarea disabled={readOnly} value={metadata.description} onChange={(event) => setMetadata(value => ({ ...value, description: event.target.value }))} /></label>
+        <label>Routing description<textarea disabled={readOnly} value={metadata.routing_description} onChange={(event) => setMetadata(value => ({ ...value, routing_description: event.target.value }))} /></label>
+        <label>Routing examples<input disabled={readOnly} value={metadata.routing_examples.join(' | ')} onChange={(event) => setMetadata(value => ({ ...value, routing_examples: event.target.value.split('|').map(item => item.trim()).filter(Boolean) }))} /></label>
+        <label className="workflow-enabled"><input type="checkbox" disabled={readOnly} checked={metadata.enabled} onChange={(event) => setMetadata(value => ({ ...value, enabled: event.target.checked }))} /> Enabled for routing</label>
+      </div>
+      <div className="workflow-editor-grid">
+        <NodePalette onAdd={addNode} />
+        <WorkflowCanvas nodes={nodes} edges={edges} onNodesChange={setNodes} onEdgesChange={setEdges} onSelectNode={setSelectedNodeId} onDropNode={addNode} />
+        <NodeInspector
+          node={selectedNode}
+          tools={tools}
+          readOnly={readOnly}
+          onChange={(next) => setNodes(previous => previous.map(node => node.id === next.id ? next : node))}
+          onDelete={() => {
+            setNodes(previous => previous.filter(node => node.id !== selectedNodeId))
+            setEdges(previous => previous.filter(edge => edge.source !== selectedNodeId && edge.target !== selectedNodeId))
+            setSelectedNodeId(null)
+          }}
+        />
+      </div>
+      <details className="workflow-schema-editor">
+        <summary>Workflow input/output schemas and limits</summary>
+        <div>
+          <label>Inputs JSON<textarea disabled={readOnly} rows={10} value={inputsText} onChange={(event) => setInputsText(event.target.value)} /></label>
+          <label>Outputs JSON<textarea disabled={readOnly} rows={10} value={outputsText} onChange={(event) => setOutputsText(event.target.value)} /></label>
+          <label>Limits JSON<textarea disabled={readOnly} rows={10} value={JSON.stringify(limits, null, 2)} onChange={(event) => { try { setLimits(JSON.parse(event.target.value)) } catch {} }} /></label>
+        </div>
+      </details>
+      <WorkflowValidationPanel result={validation} />
+      <div className="workflow-test-panel">
+        <input value={testPrompt} onChange={(event) => setTestPrompt(event.target.value)} />
+        <button className="button ghost" type="button" onClick={test} disabled={!model}>Run test</button>
+      </div>
+      <WorkflowRunInspector run={testRun} events={testEvents} />
+    </div>
+  )
+}
diff --git a/src/workflows/WorkflowList.jsx b/src/workflows/WorkflowList.jsx
new file mode 100644
index 0000000..1022048
--- /dev/null
+++ b/src/workflows/WorkflowList.jsx
@@ -0,0 +1,24 @@
+import React from 'react'
+
+export default function WorkflowList({ activeId, onCreate, onDelete, onDuplicate, onSelect, workflows }) {
+  return (
+    <div className="workflow-list">
+      <div className="workflow-list-heading">
+        <strong>Workflows</strong>
+        <button className="button" type="button" onClick={onCreate}>New</button>
+      </div>
+      {workflows.map(workflow => (
+        <div key={workflow.id} className={`workflow-list-item${workflow.id === activeId ? ' active' : ''}`} onClick={() => onSelect(workflow.id)}>
+          <div>
+            <strong>{workflow.name}</strong>
+            <small>{workflow.built_in ? 'Built-in' : `Revision ${workflow.current_version || 1}`}{workflow.enabled ? '' : ' · Disabled'}</small>
+          </div>
+          <div className="workflow-list-actions">
+            <button type="button" className="icon-button" title="Duplicate" onClick={(event) => { event.stopPropagation(); onDuplicate(workflow.id) }}>⧉</button>
+            {!workflow.built_in && <button type="button" className="icon-button" title="Delete" onClick={(event) => { event.stopPropagation(); onDelete(workflow.id) }}>×</button>}
+          </div>
+        </div>
+      ))}
+    </div>
+  )
+}
diff --git a/src/workflows/WorkflowNode.jsx b/src/workflows/WorkflowNode.jsx
new file mode 100644
index 0000000..606e377
--- /dev/null
+++ b/src/workflows/WorkflowNode.jsx
@@ -0,0 +1,19 @@
+import React from 'react'
+import { Handle, Position } from '@xyflow/react'
+
+export default function WorkflowNode({ data, selected }) {
+  return (
+    <div className={`workflow-node workflow-node-${data.nodeType}${selected ? ' selected' : ''}`}>
+      {data.nodeType !== 'input' && <Handle type="target" position={Position.Left} id="input" />}
+      <div className="workflow-node-type">{data.nodeType}</div>
+      <strong>{data.label}</strong>
+      {data.tool && <small>{data.tool}</small>}
+      {data.nodeType === 'condition' ? (
+        <>
+          <Handle type="source" position={Position.Right} id="true" style={{ top: '38%' }} />
+          <Handle type="source" position={Position.Right} id="false" style={{ top: '72%' }} />
+        </>
+      ) : data.nodeType !== 'output' && <Handle type="source" position={Position.Right} id="output" />}
+    </div>
+  )
+}
diff --git a/src/workflows/WorkflowRunInspector.jsx b/src/workflows/WorkflowRunInspector.jsx
new file mode 100644
index 0000000..90ae360
--- /dev/null
+++ b/src/workflows/WorkflowRunInspector.jsx
@@ -0,0 +1,19 @@
+import React from 'react'
+
+export default function WorkflowRunInspector({ run, events }) {
+  if (!run && !(events || []).length) return null
+  return (
+    <div className="workflow-run-inspector">
+      <strong>Test run {run?.status || 'running'}</strong>
+      {(run?.node_runs || []).map(node => (
+        <details key={node.id || node.node_id}>
+          <summary>{node.node_id}: {node.status} {node.metrics?.duration_seconds != null ? `(${node.metrics.duration_seconds.toFixed(2)}s)` : ''}</summary>
+          {node.resolved_inputs && <pre>{JSON.stringify(node.resolved_inputs, null, 2)}</pre>}
+          {node.outputs && <pre>{JSON.stringify(node.outputs, null, 2)}</pre>}
+          {node.error && <pre className="workflow-validation-error">{JSON.stringify(node.error, null, 2)}</pre>}
+        </details>
+      ))}
+      {run?.error && <pre className="workflow-validation-error">{JSON.stringify(run.error, null, 2)}</pre>}
+    </div>
+  )
+}
diff --git a/src/workflows/WorkflowValidationPanel.jsx b/src/workflows/WorkflowValidationPanel.jsx
new file mode 100644
index 0000000..114d34c
--- /dev/null
+++ b/src/workflows/WorkflowValidationPanel.jsx
@@ -0,0 +1,15 @@
+import React from 'react'
+
+export default function WorkflowValidationPanel({ result }) {
+  if (!result) return null
+  return (
+    <div className={`workflow-validation ${result.valid ? 'valid' : 'invalid'}`}>
+      <strong>{result.valid ? 'Workflow is valid' : `${result.errors?.length || 0} validation error(s)`}</strong>
+      {(result.errors || []).map((error, index) => (
+        <div key={`${error.code}-${index}`}>
+          <code>{error.node_id || error.field_path || error.code}</code> {error.message}
+        </div>
+      ))}
+    </div>
+  )
+}
diff --git a/src/workflows/WorkflowsArea.jsx b/src/workflows/WorkflowsArea.jsx
new file mode 100644
index 0000000..302d157
--- /dev/null
+++ b/src/workflows/WorkflowsArea.jsx
@@ -0,0 +1,78 @@
+import React from 'react'
+import WorkflowEditor from './WorkflowEditor'
+import WorkflowList from './WorkflowList'
+import {
+  createWorkflow,
+  deleteWorkflow,
+  duplicateWorkflow,
+  fetchTools,
+  fetchWorkflow,
+  fetchWorkflows,
+} from './workflowApi'
+
+const DEFAULT_GRAPH = {
+  schema_version: 1,
+  inputs: { prompt: { type: 'string' }, session_id: { type: ['string', 'null'] } },
+  outputs: { content: { type: 'string' } },
+  nodes: [
+    { id: 'input', type: 'input', position: { x: 80, y: 120 }, config: {} },
+    { id: 'output', type: 'output', position: { x: 440, y: 120 }, config: { value: { content: { $ref: 'input.prompt' }, sources: [], usage: {} } } },
+  ],
+  edges: [{ id: 'input-output', source: 'input', source_handle: 'output', target: 'output', target_handle: 'input' }],
+  limits: { maximum_nodes: 40, maximum_tool_calls: 20, maximum_llm_calls: 8, maximum_runtime_seconds: 300, maximum_result_chars: 120000, maximum_concurrency: 4 },
+}
+
+export default function WorkflowsArea({ apiBase, model, onWorkflowsChanged }) {
+  const [workflows, setWorkflows] = React.useState([])
+  const [tools, setTools] = React.useState([])
+  const [activeId, setActiveId] = React.useState(null)
+  const [activeWorkflow, setActiveWorkflow] = React.useState(null)
+  const [error, setError] = React.useState('')
+
+  const refresh = React.useCallback(async (preferredId = null) => {
+    try {
+      const [workflowData, toolData] = await Promise.all([fetchWorkflows(apiBase), fetchTools(apiBase)])
+      const next = workflowData.workflows || []
+      setWorkflows(next)
+      setTools(toolData.tools || [])
+      const nextId = preferredId || activeId || next[0]?.id || null
+      setActiveId(nextId)
+      setActiveWorkflow(nextId ? await fetchWorkflow(apiBase, nextId) : null)
+      onWorkflowsChanged?.(next)
+      setError('')
+    } catch (nextError) {
+      setError(nextError.message)
+    }
+  }, [activeId, apiBase, onWorkflowsChanged])
+
+  React.useEffect(() => { refresh() }, [apiBase])
+
+  const select = async (id) => {
+    setActiveId(id)
+    try { setActiveWorkflow(await fetchWorkflow(apiBase, id)) } catch (nextError) { setError(nextError.message) }
+  }
+
+  return (
+    <div className="workflows-area">
+      <WorkflowList
+        workflows={workflows}
+        activeId={activeId}
+        onSelect={select}
+        onCreate={async () => {
+          const created = await createWorkflow(apiBase, { name: 'Untitled Workflow', graph: DEFAULT_GRAPH })
+          await refresh(created.id)
+        }}
+        onDuplicate={async (id) => { const created = await duplicateWorkflow(apiBase, id); await refresh(created.id) }}
+        onDelete={async (id) => {
+          if (!window.confirm('Delete this workflow and its revisions?')) return
+          await deleteWorkflow(apiBase, id)
+          await refresh()
+        }}
+      />
+      <div className="workflows-main">
+        {error && <div className="workflow-validation-error">{error}</div>}
+        <WorkflowEditor apiBase={apiBase} model={model} tools={tools} workflow={activeWorkflow} onChanged={refresh} />
+      </div>
+    </div>
+  )
+}