feat: AI RCA draft assistant in investigation form

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FFDuBhMKvoWjrWT3ZnGmmr

app/api/incidents/[id]/ai/rca-draft/route.ts

@@ -0,0 +1,127 @@
+export const dynamic = 'force-dynamic'
+
+import { NextRequest, NextResponse } from 'next/server'
+import { createClient } from '@/lib/supabase/server'
+import { anthropic } from '@/lib/claude/client'
+
+export async function POST(
+  _request: NextRequest,
+  { params }: { params: Promise<{ id: string }> }
+) {
+  const { id } = await params
+  const supabase = await createClient()
+  const { data: { user }, error: authError } = await supabase.auth.getUser()
+  if (authError || !user) return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
+
+  const { data: profile } = await supabase.from('users').select('role').eq('id', user.id).single()
+  if (!profile || !['hse', 'admin'].includes(profile.role))
+    return NextResponse.json({ error: 'Forbidden' }, { status: 403 })
+
+  const { data: incident } = await supabase
+    .from('incidents')
+    .select(`
+      id, incident_type, description, severity, injury_involved, medical_status,
+      is_fatality, is_serious_bodily_injury, triage_notes,
+      sites (name), zones (name)
+    `)
+    .eq('id', id)
+    .single()
+  if (!incident) return NextResponse.json({ error: 'Not found' }, { status: 404 })
+
+  const inc = incident as {
+    incident_type: string
+    description: string
+    severity: number | null
+    injury_involved: boolean
+    medical_status: string | null
+    is_fatality: boolean
+    is_serious_bodily_injury: boolean
+    triage_notes: string | null
+  }
+  const siteName = (incident.sites as unknown as { name: string } | null)?.name ?? 'Unknown'
+  const zoneName = (incident.zones as unknown as { name: string } | null)?.name ?? 'Unknown'
+
+  const message = await anthropic.messages.create({
+    model: 'claude-opus-4-8',
+    thinking: { type: 'adaptive' },
+    max_tokens: 2048,
+    tools: [{
+      name: 'draft_rca',
+      description: 'Draft a 5-Why root cause analysis and CAPA suggestions for an HSE incident',
+      input_schema: {
+        type: 'object' as const,
+        properties: {
+          five_why_steps: {
+            type: 'array',
+            items: {
+              type: 'object',
+              properties: {
+                why: { type: 'string', description: 'The why question' },
+                answer: { type: 'string', description: 'The finding or answer' },
+              },
+              required: ['why', 'answer'],
+            },
+            description: '3 to 5 why steps',
+          },
+          root_cause_summary: {
+            type: 'string',
+            description: 'One-sentence root cause statement',
+          },
+          capa_suggestions: {
+            type: 'array',
+            items: { type: 'string' },
+            description: 'Up to 3 corrective/preventive action suggestions',
+          },
+        },
+        required: ['five_why_steps', 'root_cause_summary', 'capa_suggestions'],
+      },
+    }],
+    tool_choice: { type: 'tool', name: 'draft_rca' },
+    messages: [{
+      role: 'user',
+      content: `You are an experienced HSE investigator for a Malaysian 3PL warehouse. Draft a 5-Why root cause analysis for this incident.
+
+Site: ${siteName}
+Zone: ${zoneName}
+Incident type: ${inc.incident_type}
+Description: ${inc.description}
+Severity: ${inc.severity ?? 'not yet assigned'}/5
+Injury involved: ${inc.injury_involved ? `yes — ${inc.medical_status}` : 'no'}
+Fatality: ${inc.is_fatality ? 'yes' : 'no'}
+Serious bodily injury: ${inc.is_serious_bodily_injury ? 'yes' : 'no'}
+Triage notes: ${inc.triage_notes ?? 'none'}
+
+Provide 3–5 Why steps drilling from immediate cause to root cause. Give a one-sentence root cause statement. Suggest 3 corrective/preventive actions appropriate for a Malaysian warehouse context.`,
+    }],
+  })
+
+  const toolBlock = message.content.find(b => b.type === 'tool_use')
+  if (!toolBlock || toolBlock.type !== 'tool_use')
+    return NextResponse.json({ error: 'AI draft failed' }, { status: 500 })
+
+  const draft = toolBlock.input as {
+    five_why_steps?: unknown
+    root_cause_summary?: unknown
+    capa_suggestions?: unknown
+  }
+
+  if (
+    !Array.isArray(draft.five_why_steps) ||
+    typeof draft.root_cause_summary !== 'string' ||
+    !Array.isArray(draft.capa_suggestions)
+  ) {
+    return NextResponse.json({ error: 'AI returned unexpected structure' }, { status: 500 })
+  }
+
+  await supabase.rpc('write_audit_log', {
+    p_table_name: 'incidents',
+    p_record_id: id,
+    p_action: 'ai_rca_draft',
+    p_new_value: {
+      root_cause_summary: draft.root_cause_summary,
+      model: 'claude-opus-4-8',
+    } as never,
+  })
+
+  return NextResponse.json(draft)
+}

components/incidents/investigation-form.tsx

@@ -40,6 +40,7 @@ export function InvestigationForm({ incidentId, existingInvestigationId }: Props
   const [complete, setComplete] = useState(false)
   const [saving, setSaving] = useState(false)
   const [error, setError] = useState<string | null>(null)
+  const [aiDraftLoading, setAiDraftLoading] = useState(false)
 
   function addWhyStep() {
     if (fiveWhy.length >= 5) return
@@ -57,6 +58,31 @@ export function InvestigationForm({ incidentId, existingInvestigationId }: Props
     setFishbone(fishbone.map((c, i) => i === catIdx ? { ...c, causes: [...c.causes, ''] } : c))
   }
 
+  async function getAiDraft() {
+    setAiDraftLoading(true)
+    try {
+      const res = await fetch(`/api/incidents/${incidentId}/ai/rca-draft`, { method: 'POST' })
+      if (!res.ok) return
+      const draft = await res.json() as {
+        five_why_steps: Array<{ why: string; answer: string }>
+        root_cause_summary: string
+        capa_suggestions: string[]
+      }
+      if (draft.five_why_steps?.length > 0) {
+        setMethod('five_why')
+        setFiveWhy(draft.five_why_steps)
+      }
+      if (draft.root_cause_summary) setRootCause(draft.root_cause_summary)
+      if (draft.capa_suggestions?.length > 0) {
+        setFindingsText(draft.capa_suggestions.map((s, i) => `${i + 1}. ${s}`).join('\n'))
+      }
+    } catch {
+      // Non-blocking — investigator can fill manually
+    } finally {
+      setAiDraftLoading(false)
+    }
+  }
+
   async function handleSubmit(e: React.FormEvent) {
     e.preventDefault()
     setSaving(true)
@@ -99,6 +125,16 @@ export function InvestigationForm({ incidentId, existingInvestigationId }: Props
 
   return (
     <form onSubmit={handleSubmit} className="space-y-6">
+      <div className="flex justify-end">
+        <button
+          type="button"
+          onClick={getAiDraft}
+          disabled={aiDraftLoading}
+          className="bg-purple-50 text-purple-700 border border-purple-300 rounded-lg px-3 py-1.5 text-xs font-semibold disabled:opacity-50 hover:bg-purple-100"
+        >
+          {aiDraftLoading ? 'Drafting…' : 'Get AI Draft'}
+        </button>
+      </div>
       <div>
         <label className="block text-sm font-medium text-gray-700 mb-1">RCA Method</label>
         <div className="flex gap-3">