feat: add Create Flow from Session button to session detail page (Task 22)

Adds sessionToFlow API client, exports from api/index.ts, and integrates
a prominent "Create Flow from Session" button on SessionDetailPage for
completed sessions. Generates a procedural flow via AI then navigates
to the procedural editor.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/src/api/index.ts

@@ -23,3 +23,4 @@ export { kbAcceleratorApi } from './kbAccelerator'
 export { scriptsApi } from './scripts'
 export { integrationsApi, sessionPsaApi } from './integrations'
 export { sidebarApi } from './sidebar'
+export { sessionToFlowApi } from './sessionToFlow'

frontend/src/api/sessionToFlow.ts

@@ -0,0 +1,16 @@
+import { apiClient } from './client'
+
+interface SessionToFlowResponse {
+  name: string
+  description: string
+  tree_type: string
+  tags: string[]
+  tree_structure: Record<string, unknown>
+}
+
+export const sessionToFlowApi = {
+  generate: async (sessionId: string): Promise<SessionToFlowResponse> => {
+    const { data } = await apiClient.post('/ai/session-to-flow', { session_id: sessionId })
+    return data
+  },
+}

frontend/src/pages/SessionDetailPage.tsx

@@ -1,9 +1,11 @@
 import { useEffect, useState } from 'react'
 import { useParams, useNavigate } from 'react-router-dom'
-import { Copy, Check, Eye, Save, Share2, CheckCircle2, AlertTriangle, ArrowUpRight, HelpCircle, Flag } from 'lucide-react'
+import { Copy, Check, Eye, Save, Share2, CheckCircle2, AlertTriangle, ArrowUpRight, HelpCircle, Flag, Sparkles, Loader2 } from 'lucide-react'
 import { Button } from '@/components/ui/Button'
 import { sessionsApi } from '@/api/sessions'
 import { stepsApi } from '@/api/steps'
+import { treesApi } from '@/api/trees'
+import { sessionToFlowApi } from '@/api/sessionToFlow'
 import { ExportPreviewModal } from '@/components/session/ExportPreviewModal'
 import { SaveSessionAsTreeModal } from '@/components/session/SaveSessionAsTreeModal'
 import { ShareSessionModal } from '@/components/session/ShareSessionModal'
@@ -19,6 +21,7 @@ import { hasRatedSession, markSessionRated } from '@/lib/sessionRatings'
 import { Spinner } from '@/components/common/Spinner'
 import { cn } from '@/lib/utils'
 import { toast } from '@/lib/toast'
+import { getTreeEditorPath } from '@/lib/routing'
 
 export function SessionDetailPage() {
   const { id } = useParams<{ id: string }>()
@@ -46,6 +49,7 @@ export function SessionDetailPage() {
   const [includeSummary, setIncludeSummary] = useState(false)
   const [redactionMode, setRedactionMode] = useState<'none' | 'mask'>('none')
   const [redactionSummary, setRedactionSummary] = useState<RedactionSummary | null>(null)
+  const [isGeneratingFlow, setIsGeneratingFlow] = useState(false)
 
   useEffect(() => {
     if (id) {
@@ -247,6 +251,28 @@ export function SessionDetailPage() {
     }
   }
 
+  const handleCreateFlowFromSession = async () => {
+    if (!session) return
+    setIsGeneratingFlow(true)
+    try {
+      const flowData = await sessionToFlowApi.generate(session.id)
+      const tree = await treesApi.create({
+        name: flowData.name,
+        description: flowData.description,
+        tree_type: flowData.tree_type,
+        tree_structure: flowData.tree_structure,
+        tags: flowData.tags,
+      })
+      toast.success('Flow generated! Opening editor...')
+      navigate(getTreeEditorPath(tree.id, 'procedural'))
+    } catch (err) {
+      console.error('Failed to generate flow from session:', err)
+      toast.error('Failed to generate flow. Please try again.')
+    } finally {
+      setIsGeneratingFlow(false)
+    }
+  }
+
   const getDefaultTreeName = () => {
     if (!session) return ''
     const treeName = session.tree_snapshot?.name || 'Tree'
@@ -398,7 +424,27 @@ export function SessionDetailPage() {
             </Button>
           </div>
         </div>
-      ) : !session.completed_at ? (
+      ) : null}
+
+      {/* Create Flow from Session — only for completed sessions */}
+      {session.completed_at && (
+        <div className="mb-4">
+          <Button
+            onClick={handleCreateFlowFromSession}
+            disabled={isGeneratingFlow}
+            className="bg-gradient-brand text-[#101114] font-semibold rounded-[10px] hover:opacity-90 active:scale-[0.97] disabled:opacity-60"
+          >
+            {isGeneratingFlow ? (
+              <Loader2 className="h-4 w-4 animate-spin" />
+            ) : (
+              <Sparkles className="h-4 w-4" />
+            )}
+            {isGeneratingFlow ? 'Generating Flow...' : 'Create Flow from Session'}
+          </Button>
+        </div>
+      )}
+
+      {!session.completed_at ? (
         /* In-progress banner */
         <div className="mb-6 flex items-center justify-between gap-4 rounded-xl border border-amber-500/20 bg-amber-500/5 px-5 py-4">
           <div className="flex items-center gap-3">