feat: add frontend orchestration mode UI to workflow designer

- Add OrchestrationModePanel with mode cards for all 5 modes (single,
  sequential, concurrent, handoff, group-chat)
- Add handoff settings panel: triage agent selector, tool-call
  filtering, return-to-previous toggle, custom instructions
- Add group-chat settings panel: selection strategy display, max
  rounds input
- Add auto-inference indicator when mode is not explicitly set
- Add scaffold dialog when changing mode with existing agents
- Add mode badge (top-left pill) on workflow graph canvas
- Wire orchestration mode panel into WorkflowSettingsPanel above
  general settings

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

src/renderer/components/WorkflowEditor.tsx

@@ -21,6 +21,7 @@ import { WorkflowGraphCanvas } from './workflow/WorkflowGraphCanvas';
 import { ExportDropdown, ExportModal, ImportModal } from './workflow/WorkflowExportImportPanel';
 import { WorkflowGraphInspector } from './workflow/WorkflowGraphInspector';
 import { WorkflowNodePalette } from './workflow/WorkflowNodePalette';
+import { OrchestrationModePanel } from './workflow/OrchestrationModePanel';
 
 interface WorkflowEditorProps {
   availableModels: ReadonlyArray<ModelDefinition>;
@@ -655,6 +656,12 @@ function WorkflowSettingsPanel({
       <h4 className="mb-3 text-[12px] font-semibold uppercase tracking-wider text-[var(--color-text-muted)]">
         Settings
       </h4>
+
+      {/* Orchestration mode — prominent, above general settings */}
+      <div className="mb-5">
+        <OrchestrationModePanel workflow={workflow} onChange={onChange} />
+      </div>
+
       <div className="grid grid-cols-2 gap-4">
         <InputField
           label="Name"

src/renderer/components/workflow/OrchestrationModePanel.tsx

@@ -0,0 +1,503 @@
+import { useCallback, useMemo, useState } from 'react';
+import {
+  ArrowRightLeft,
+  Bot,
+  ChevronDown,
+  Layers,
+  MessageCircle,
+  Repeat,
+  Route,
+  User,
+} from 'lucide-react';
+
+import type {
+  HandoffModeSettings,
+  GroupChatModeSettings,
+  WorkflowDefinition,
+  WorkflowNode,
+  WorkflowOrchestrationMode,
+} from '@shared/domain/workflow';
+import {
+  createDefaultModeSettings,
+  inferWorkflowOrchestrationMode,
+  isBuilderBasedMode,
+  isGraphBasedMode,
+  scaffoldGraphForMode,
+} from '@shared/domain/workflow';
+import { FormField, InfoCallout, SelectInput, ToggleSwitch } from '@renderer/components/ui';
+
+/* ── Mode metadata ─────────────────────────────────────────── */
+
+interface ModeOption {
+  value: WorkflowOrchestrationMode;
+  label: string;
+  description: string;
+  icon: typeof Bot;
+  accentClass: string;
+}
+
+const modeOptions: ModeOption[] = [
+  {
+    value: 'single',
+    label: 'Single Agent',
+    description: 'One agent handles the full conversation directly.',
+    icon: User,
+    accentClass: 'text-emerald-400',
+  },
+  {
+    value: 'sequential',
+    label: 'Sequential',
+    description: 'Agents execute in order, each seeing the full conversation history.',
+    icon: ArrowRightLeft,
+    accentClass: 'text-sky-400',
+  },
+  {
+    value: 'concurrent',
+    label: 'Concurrent',
+    description: 'Agents execute in parallel via fan-out, results collected at barrier.',
+    icon: Layers,
+    accentClass: 'text-amber-400',
+  },
+  {
+    value: 'handoff',
+    label: 'Handoff',
+    description: 'Triage agent routes requests to specialists via handoff tool calls.',
+    icon: Route,
+    accentClass: 'text-violet-400',
+  },
+  {
+    value: 'group-chat',
+    label: 'Group Chat',
+    description: 'Agents take turns in a managed conversation loop.',
+    icon: MessageCircle,
+    accentClass: 'text-rose-400',
+  },
+];
+
+const modeMap = new Map(modeOptions.map((m) => [m.value, m]));
+
+/* ── Scaffold confirmation dialog ──────────────────────────── */
+
+function ScaffoldDialog({
+  fromMode,
+  toMode,
+  onAccept,
+  onDecline,
+}: {
+  fromMode: string;
+  toMode: WorkflowOrchestrationMode;
+  onAccept: () => void;
+  onDecline: () => void;
+}) {
+  const target = modeMap.get(toMode);
+  return (
+    <div
+      className="fixed inset-0 z-50 flex items-center justify-center bg-black/60 backdrop-blur-sm"
+      role="dialog"
+      aria-modal="true"
+      aria-labelledby="scaffold-dialog-title"
+    >
+      <div
+        className="mx-4 w-full max-w-md animate-[palette-enter_0.2s_ease-out] rounded-2xl border border-[var(--color-border)] bg-[var(--color-surface-2)] p-6 shadow-2xl"
+      >
+        <h3
+          id="scaffold-dialog-title"
+          className="mb-2 text-[14px] font-semibold text-[var(--color-text-primary)]"
+        >
+          Restructure graph for {target?.label ?? toMode}?
+        </h3>
+        <p className="mb-5 text-[13px] leading-relaxed text-[var(--color-text-secondary)]">
+          This will update edges to match the <span className="font-medium text-[var(--color-text-primary)]">{target?.label ?? toMode}</span> topology while keeping your existing agents.
+          {fromMode && (
+            <span className="mt-1 block text-[12px] text-[var(--color-text-muted)]">
+              Changing from {fromMode}.
+            </span>
+          )}
+        </p>
+        <div className="flex items-center justify-end gap-2.5">
+          <button
+            type="button"
+            onClick={onDecline}
+            className="rounded-lg px-4 py-2 text-[13px] text-[var(--color-text-secondary)] transition-all duration-200 hover:bg-[var(--color-surface-3)] hover:text-[var(--color-text-primary)]"
+          >
+            Keep current graph
+          </button>
+          <button
+            type="button"
+            onClick={onAccept}
+            className="rounded-lg bg-[var(--color-accent)] px-4 py-2 text-[13px] font-medium text-white transition-all duration-200 hover:bg-[var(--color-accent-hover)]"
+          >
+            Restructure
+          </button>
+        </div>
+      </div>
+    </div>
+  );
+}
+
+/* ── Mode selector card ────────────────────────────────────── */
+
+function ModeCard({
+  option,
+  selected,
+  onClick,
+}: {
+  option: ModeOption;
+  selected: boolean;
+  onClick: () => void;
+}) {
+  const Icon = option.icon;
+  return (
+    <button
+      type="button"
+      onClick={onClick}
+      className={`group flex items-start gap-3 rounded-xl border px-3.5 py-3 text-left transition-all duration-200 ${
+        selected
+          ? 'border-[var(--color-accent)]/40 bg-[var(--color-accent-muted)] shadow-[0_0_0_1px_rgba(36,92,249,0.15),0_0_16px_rgba(36,92,249,0.06)]'
+          : 'border-[var(--color-border)] bg-[var(--color-surface-1)] hover:border-[var(--color-border-glow)] hover:bg-[var(--color-surface-2)]'
+      }`}
+      aria-pressed={selected}
+    >
+      <div className={`mt-0.5 flex size-7 shrink-0 items-center justify-center rounded-lg ${
+        selected ? 'bg-[var(--color-accent)]/15' : 'bg-[var(--color-surface-3)]'
+      }`}>
+        <Icon className={`size-3.5 ${selected ? 'text-[var(--color-accent)]' : option.accentClass}`} />
+      </div>
+      <div className="min-w-0 flex-1">
+        <div className={`text-[13px] font-medium ${
+          selected ? 'text-[var(--color-text-primary)]' : 'text-[var(--color-text-secondary)] group-hover:text-[var(--color-text-primary)]'
+        }`}>
+          {option.label}
+        </div>
+        <div className="mt-0.5 text-[11px] leading-snug text-[var(--color-text-muted)]">
+          {option.description}
+        </div>
+      </div>
+    </button>
+  );
+}
+
+/* ── Handoff settings sub-panel ────────────────────────────── */
+
+function HandoffSettingsPanel({
+  settings,
+  agentNodes,
+  onChange,
+}: {
+  settings: HandoffModeSettings;
+  agentNodes: WorkflowNode[];
+  onChange: (settings: HandoffModeSettings) => void;
+}) {
+  const triageOptions = useMemo(() => [
+    { value: '', label: 'First agent (default)' },
+    ...agentNodes.map((node) => ({
+      value: node.id,
+      label: node.label || (node.config.kind === 'agent' ? node.config.name : node.id),
+    })),
+  ], [agentNodes]);
+
+  const filteringOptions = [
+    { value: 'none', label: 'None — All tools available' },
+    { value: 'handoff-only', label: 'Handoff-only — Restrict to handoff tools' },
+    { value: 'all', label: 'All — Full tool filtering' },
+  ];
+
+  return (
+    <div className="space-y-3.5 rounded-xl border border-[var(--color-border)] bg-[var(--color-surface-1)] p-4">
+      <div className="flex items-center gap-2">
+        <Route className="size-3.5 text-violet-400" />
+        <span className="text-[12px] font-semibold uppercase tracking-wider text-[var(--color-text-muted)]">
+          Handoff Settings
+        </span>
+      </div>
+
+      <FormField label="Triage Agent">
+        <SelectInput
+          value={settings.triageAgentNodeId ?? ''}
+          options={triageOptions}
+          onChange={(v) => onChange({ ...settings, triageAgentNodeId: v || undefined })}
+        />
+      </FormField>
+
+      <FormField label="Tool-Call Filtering">
+        <SelectInput
+          value={settings.toolCallFiltering}
+          options={filteringOptions}
+          onChange={(v) => onChange({ ...settings, toolCallFiltering: v as HandoffModeSettings['toolCallFiltering'] })}
+        />
+      </FormField>
+
+      <div className="flex items-center justify-between rounded-lg border border-[var(--color-border)] bg-[var(--color-surface-2)] px-3.5 py-2.5">
+        <div>
+          <div className="text-[13px] font-medium text-[var(--color-text-primary)]">Return to Previous</div>
+          <p className="text-[11px] text-[var(--color-text-muted)]">Allow specialists to hand back to the previous agent</p>
+        </div>
+        <button type="button" className="cursor-pointer" onClick={() => onChange({ ...settings, returnToPrevious: !settings.returnToPrevious })}>
+          <ToggleSwitch enabled={settings.returnToPrevious} />
+        </button>
+      </div>
+
+      <FormField label="Custom Handoff Instructions">
+        <textarea
+          className="w-full rounded-lg border border-[var(--color-border)] bg-[var(--color-surface-2)] px-3 py-2 text-[13px] text-[var(--color-text-primary)] outline-none transition-all duration-200 placeholder:text-[var(--color-text-muted)] focus:border-[var(--color-border-glow)] focus:shadow-[0_0_0_1px_rgba(36,92,249,0.15),0_0_12px_rgba(36,92,249,0.08)]"
+          rows={3}
+          placeholder="Override default handoff guidance (optional)"
+          value={settings.handoffInstructions ?? ''}
+          onChange={(e) => onChange({ ...settings, handoffInstructions: e.target.value || undefined })}
+        />
+      </FormField>
+    </div>
+  );
+}
+
+/* ── Group-chat settings sub-panel ─────────────────────────── */
+
+function GroupChatSettingsPanel({
+  settings,
+  onChange,
+}: {
+  settings: GroupChatModeSettings;
+  onChange: (settings: GroupChatModeSettings) => void;
+}) {
+  return (
+    <div className="space-y-3.5 rounded-xl border border-[var(--color-border)] bg-[var(--color-surface-1)] p-4">
+      <div className="flex items-center gap-2">
+        <MessageCircle className="size-3.5 text-rose-400" />
+        <span className="text-[12px] font-semibold uppercase tracking-wider text-[var(--color-text-muted)]">
+          Group Chat Settings
+        </span>
+      </div>
+
+      <FormField label="Selection Strategy">
+        <div className="flex items-center gap-2 rounded-lg border border-[var(--color-border)] bg-[var(--color-surface-2)] px-3.5 py-2.5">
+          <Repeat className="size-3.5 text-[var(--color-text-muted)]" />
+          <span className="text-[13px] text-[var(--color-text-primary)]">Round Robin</span>
+          <span className="ml-auto text-[11px] text-[var(--color-text-muted)]">Only strategy</span>
+        </div>
+      </FormField>
+
+      <FormField label="Max Rounds">
+        <input
+          type="number"
+          min={1}
+          max={100}
+          className="w-full rounded-lg border border-[var(--color-border)] bg-[var(--color-surface-2)] px-3 py-2 text-[13px] text-[var(--color-text-primary)] outline-none transition-all duration-200 placeholder:text-[var(--color-text-muted)] focus:border-[var(--color-border-glow)] focus:shadow-[0_0_0_1px_rgba(36,92,249,0.15),0_0_12px_rgba(36,92,249,0.08)]"
+          placeholder="5"
+          value={settings.maxRounds}
+          onChange={(e) => {
+            const raw = parseInt(e.target.value, 10);
+            onChange({ ...settings, maxRounds: Number.isNaN(raw) ? 5 : Math.max(1, Math.min(100, raw)) });
+          }}
+        />
+      </FormField>
+    </div>
+  );
+}
+
+/* ── Main orchestration mode panel ─────────────────────────── */
+
+export function OrchestrationModePanel({
+  workflow,
+  onChange,
+}: {
+  workflow: WorkflowDefinition;
+  onChange: (workflow: WorkflowDefinition) => void;
+}) {
+  const [expanded, setExpanded] = useState(true);
+  const [scaffoldRequest, setScaffoldRequest] = useState<{
+    newMode: WorkflowOrchestrationMode;
+    fromLabel: string;
+  } | null>(null);
+
+  const currentMode = workflow.settings.orchestrationMode;
+  const inferredMode = useMemo(() => inferWorkflowOrchestrationMode(workflow), [workflow]);
+  const effectiveMode = currentMode ?? inferredMode;
+  const effectiveMeta = modeMap.get(effectiveMode);
+
+  const agentNodes = useMemo(
+    () => workflow.graph.nodes.filter((n) => n.kind === 'agent'),
+    [workflow.graph.nodes],
+  );
+
+  const handoffSettings: HandoffModeSettings = useMemo(
+    () => workflow.settings.modeSettings?.handoff ?? createDefaultModeSettings('handoff')!.handoff!,
+    [workflow.settings.modeSettings?.handoff],
+  );
+
+  const groupChatSettings: GroupChatModeSettings = useMemo(
+    () => workflow.settings.modeSettings?.groupChat ?? createDefaultModeSettings('group-chat')!.groupChat!,
+    [workflow.settings.modeSettings?.groupChat],
+  );
+
+  const applyModeChange = useCallback(
+    (newMode: WorkflowOrchestrationMode, restructure: boolean) => {
+      const modeSettings = createDefaultModeSettings(newMode);
+      const base: WorkflowDefinition = {
+        ...workflow,
+        settings: {
+          ...workflow.settings,
+          orchestrationMode: newMode,
+          modeSettings: modeSettings
+            ? { ...workflow.settings.modeSettings, ...modeSettings }
+            : workflow.settings.modeSettings,
+        },
+      };
+
+      if (restructure) {
+        const existingAgents = workflow.graph.nodes.filter((n) => n.kind === 'agent');
+        const newGraph = scaffoldGraphForMode(newMode, existingAgents.length > 0 ? existingAgents : undefined);
+        onChange({ ...base, graph: newGraph });
+      } else {
+        onChange(base);
+      }
+    },
+    [workflow, onChange],
+  );
+
+  const handleModeSelect = useCallback(
+    (newMode: WorkflowOrchestrationMode) => {
+      if (newMode === currentMode) return;
+
+      const hasAgents = agentNodes.length > 0;
+      const fromLabel = currentMode
+        ? (modeMap.get(currentMode)?.label ?? currentMode)
+        : `Auto (${modeMap.get(inferredMode)?.label ?? inferredMode})`;
+
+      if (hasAgents) {
+        setScaffoldRequest({ newMode, fromLabel });
+      } else {
+        applyModeChange(newMode, true);
+      }
+    },
+    [currentMode, inferredMode, agentNodes.length, applyModeChange],
+  );
+
+  const handleHandoffChange = useCallback(
+    (handoff: HandoffModeSettings) => {
+      onChange({
+        ...workflow,
+        settings: {
+          ...workflow.settings,
+          modeSettings: { ...workflow.settings.modeSettings, handoff },
+        },
+      });
+    },
+    [workflow, onChange],
+  );
+
+  const handleGroupChatChange = useCallback(
+    (groupChat: GroupChatModeSettings) => {
+      onChange({
+        ...workflow,
+        settings: {
+          ...workflow.settings,
+          modeSettings: { ...workflow.settings.modeSettings, groupChat },
+        },
+      });
+    },
+    [workflow, onChange],
+  );
+
+  return (
+    <>
+      <div className="space-y-4">
+        {/* Section header */}
+        <button
+          type="button"
+          onClick={() => setExpanded(!expanded)}
+          className="flex w-full items-center justify-between"
+          aria-expanded={expanded}
+        >
+          <h4 className="text-[12px] font-semibold uppercase tracking-wider text-[var(--color-text-muted)]">
+            Orchestration Mode
+          </h4>
+          <div className="flex items-center gap-2">
+            {!currentMode && (
+              <span className="rounded-md bg-[var(--color-surface-3)] px-2 py-0.5 text-[11px] font-medium text-[var(--color-text-muted)]">
+                Auto
+              </span>
+            )}
+            {effectiveMeta && (
+              <span className={`text-[11px] font-medium ${effectiveMeta.accentClass}`}>
+                {effectiveMeta.label}
+              </span>
+            )}
+            <ChevronDown
+              className={`size-3.5 text-[var(--color-text-muted)] transition-transform duration-200 ${expanded ? 'rotate-180' : ''}`}
+            />
+          </div>
+        </button>
+
+        {expanded && (
+          <div className="space-y-4">
+            {/* Mode cards */}
+            <div className="grid grid-cols-1 gap-2">
+              {modeOptions.map((option) => (
+                <ModeCard
+                  key={option.value}
+                  option={option}
+                  selected={effectiveMode === option.value}
+                  onClick={() => handleModeSelect(option.value)}
+                />
+              ))}
+            </div>
+
+            {/* Auto-inference indicator */}
+            {!currentMode && (
+              <InfoCallout>
+                Mode is auto-inferred from graph shape as <span className="font-medium text-[var(--color-text-primary)]">{effectiveMeta?.label}</span>.
+                Select a mode explicitly to lock it.
+              </InfoCallout>
+            )}
+
+            {/* Builder-based mode info */}
+            {isBuilderBasedMode(effectiveMode) && (
+              <InfoCallout>
+                In {effectiveMeta?.label} mode, the framework manages agent routing automatically. The graph defines participants.
+              </InfoCallout>
+            )}
+
+            {/* Graph-based mode info */}
+            {isGraphBasedMode(effectiveMode) && currentMode && (
+              <InfoCallout>
+                This mode uses the graph topology for execution. Connect agents with the appropriate edge types.
+              </InfoCallout>
+            )}
+
+            {/* Mode-specific settings */}
+            {effectiveMode === 'handoff' && (
+              <HandoffSettingsPanel
+                settings={handoffSettings}
+                agentNodes={agentNodes}
+                onChange={handleHandoffChange}
+              />
+            )}
+
+            {effectiveMode === 'group-chat' && (
+              <GroupChatSettingsPanel
+                settings={groupChatSettings}
+                onChange={handleGroupChatChange}
+              />
+            )}
+          </div>
+        )}
+      </div>
+
+      {/* Scaffold confirmation dialog */}
+      {scaffoldRequest && (
+        <ScaffoldDialog
+          fromMode={scaffoldRequest.fromLabel}
+          toMode={scaffoldRequest.newMode}
+          onAccept={() => {
+            applyModeChange(scaffoldRequest.newMode, true);
+            setScaffoldRequest(null);
+          }}
+          onDecline={() => {
+            applyModeChange(scaffoldRequest.newMode, false);
+            setScaffoldRequest(null);
+          }}
+        />
+      )}
+    </>
+  );
+}

src/renderer/components/workflow/WorkflowGraphCanvas.tsx

@@ -1,4 +1,4 @@
-import { useCallback, useEffect, useRef, useState } from 'react';
+import { useCallback, useEffect, useMemo, useRef, useState } from 'react';
 import {
   ReactFlow,
   ReactFlowProvider,
@@ -19,8 +19,9 @@ import {
 import '@xyflow/react/dist/style.css';
 import { LayoutGrid, Maximize2, ZoomIn, ZoomOut } from 'lucide-react';
 
-import type { WorkflowDefinition, WorkflowGraph } from '@shared/domain/workflow';
+import type { WorkflowDefinition, WorkflowGraph, WorkflowOrchestrationMode } from '@shared/domain/workflow';
 import type { ModelDefinition } from '@shared/domain/models';
+import { inferWorkflowOrchestrationMode } from '@shared/domain/workflow';
 import {
   addWorkflowEdge,
   autoLayoutWorkflowGraph,
@@ -60,6 +61,19 @@ function WorkflowGraphCanvasInner({
   const draggingRef = useRef(false);
   const [zoomLevel, setZoomLevel] = useState(1);
 
+  const modeBadge = useMemo(() => {
+    const mode = inferWorkflowOrchestrationMode(workflow);
+    const explicit = !!workflow.settings.orchestrationMode;
+    const meta: Record<WorkflowOrchestrationMode, { label: string; icon: string; color: string }> = {
+      single: { label: 'Single', icon: '●', color: 'text-emerald-400' },
+      sequential: { label: 'Sequential', icon: '→', color: 'text-sky-400' },
+      concurrent: { label: 'Concurrent', icon: '⇉', color: 'text-amber-400' },
+      handoff: { label: 'Handoff', icon: '⇢', color: 'text-violet-400' },
+      'group-chat': { label: 'Group Chat', icon: '⟳', color: 'text-rose-400' },
+    };
+    return { mode, explicit, ...meta[mode] };
+  }, [workflow]);
+
   const [nodes, setNodes, onNodesChangeBase] = useNodesState(
     toCanvasNodes(graph, availableModels, workflows),
   );
@@ -249,6 +263,21 @@ function WorkflowGraphCanvasInner({
         deleteKeyCode="Delete"
       >
         <Background variant={BackgroundVariant.Dots} gap={20} size={1} color="#1a1e2e" />
+        <Panel position="top-left">
+          <div className="flex items-center gap-1.5 rounded-lg border border-[var(--color-border)] bg-[var(--color-surface-2)]/90 px-2.5 py-1.5 shadow-sm backdrop-blur">
+            <span className={`text-[12px] font-semibold leading-none ${modeBadge.color}`}>
+              {modeBadge.icon}
+            </span>
+            <span className="text-[11px] font-medium text-[var(--color-text-secondary)]">
+              {modeBadge.label}
+            </span>
+            {!modeBadge.explicit && (
+              <span className="rounded bg-[var(--color-surface-3)] px-1.5 py-px text-[10px] text-[var(--color-text-muted)]">
+                auto
+              </span>
+            )}
+          </div>
+        </Panel>
         <MiniMap
           className="!rounded-lg !border !border-[var(--color-border)] !bg-[var(--color-surface-1)]"
           maskColor="rgba(0,0,0,0.6)"