feat(ai): add AI chart suggestions in TipTap editor

Implement slash command "/suggest-charts" that analyzes note content
and suggests 3 appropriate chart types with visual previews.

Created:
- chart-suggestion.tool.ts: AI tool for data extraction and chart recommendations
- suggest-charts/route.ts: API endpoint for chart suggestions
- chart-suggestion.service.ts: Frontend service layer
- chart-suggestions-dialog.tsx: Modal with 3 chart proposals and thumbnails
- tiptap-chart-extension.tsx: TipTap Node extension for rendering chart blocks

Modified:
- rich-text-editor.tsx: Added slash command, toolbar button, and dialog integration

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

memento-note/app/api/ai/suggest-charts/route.ts

@@ -0,0 +1,174 @@
+import { generateText } from 'ai'
+import { resolveAiRouteWithTiming } from '@/lib/ai/router'
+import { runLaneWithBillingUser, willUseByokForLane } from '@/lib/ai/provider-for-user'
+import { getSystemConfig } from '@/lib/config'
+import { prisma } from '@/lib/prisma'
+import { auth } from '@/auth'
+import { toolRegistry } from '@/lib/ai/tools'
+import { checkEntitlementOrThrow, QuotaExceededError } from '@/lib/entitlements'
+import { trackFeatureUsage } from '@/lib/usage-tracker'
+
+export const maxDuration = 30
+
+interface SuggestChartsRequest {
+  content: string
+  selection?: string | null
+  noteId?: string
+}
+
+interface ChartSuggestion {
+  type: 'bar' | 'horizontal-bar' | 'line' | 'area' | 'pie' | 'radar' | 'funnel' | 'gauge'
+  title: string
+  data: { label: string; value: number }[]
+  description: string
+  rationale?: string
+}
+
+interface SuggestChartsResponse {
+  suggestions: ChartSuggestion[]
+  analyzedText: string
+  detectedData: string
+  hasData: boolean
+}
+
+export async function POST(req: Request) {
+  // 1. Auth check
+  const session = await auth()
+  if (!session?.user?.id) {
+    return new Response('Unauthorized', { status: 401 })
+  }
+  const userId = session.user.id
+
+  // 1.5 Quota check
+  try {
+    const sysConfigEarly = await getSystemConfig()
+    const { usedByok: willUseByok } = await willUseByokForLane('suggest-charts', sysConfigEarly, userId)
+    if (!willUseByok) {
+      await checkEntitlementOrThrow(userId, 'ai')
+    }
+  } catch (err) {
+    if (err instanceof QuotaExceededError) {
+      return Response.json(err.toJSON(), { status: 402 })
+    }
+    console.error('[suggest-charts] Quota check error (fail-open):', err)
+  }
+
+  // 2. Parse request body
+  const body = await req.json() as SuggestChartsRequest
+  const { content, selection, noteId } = body
+
+  if (!content || content.trim().length === 0) {
+    return Response.json({
+      error: 'Content is required',
+      suggestions: [],
+      analyzedText: '',
+      detectedData: '',
+      hasData: false,
+    } satisfies SuggestChartsResponse, { status: 400 })
+  }
+
+  const textToAnalyze = selection && selection.trim() ? selection.trim() : content.trim()
+
+  // 3. Build AI context
+  const sysConfig = await getSystemConfig()
+  const { provider, model, timingInfo } = await resolveAiRouteWithTiming('suggest-charts', sysConfig)
+
+  // Build context for AI
+  const toolContext = {
+    userId,
+    noteId,
+    config: sysConfig,
+  }
+
+  // Use the suggest_charts tool
+  const suggestChartsTool = toolRegistry.get('suggest_charts')
+  const tools = suggestChartsTool ? { suggest_charts: suggestChartsTool.buildTool(toolContext) } : {}
+
+  try {
+    // 4. Call AI to analyze and suggest
+    const { text } = await generateText({
+      model: provider(model),
+      system: `You are a data visualization assistant. Analyze the provided text and suggest appropriate chart types.
+
+CRITICAL: Extract ONLY numerical data present in the text. Do NOT invent values.
+- If fewer than 2 data points exist, return hasData=false with empty suggestions
+- Each suggestion must use the SAME extracted data (only chart type differs)
+- Return exactly 3 suggestions when data exists
+- Provide clear rationale for each chart type choice
+
+Response format (JSON):
+{
+  "suggestions": [
+    {
+      "type": "bar|horizontal-bar|line|area|pie|radar|funnel|gauge",
+      "title": "Chart title",
+      "data": [{"label": "Category", "value": 123}],
+      "description": "What this chart shows",
+      "rationale": "Why this chart type suits the data"
+    }
+  ],
+  "analyzedText": "Text that was analyzed",
+  "detectedData": "Description of what data was found",
+  "hasData": true
+}`,
+      messages: [
+        {
+          role: 'user',
+          content: `Analyze this text and suggest 3 appropriate chart types:\n\n${textToAnalyze}`,
+        },
+      ],
+      tools,
+      temperature: 0.3,
+    })
+
+    // 5. Parse AI response
+    let parsed: SuggestChartsResponse
+    try {
+      // Try to extract JSON from the response
+      const jsonMatch = text.match(/\{[\s\S]*\}/)
+      if (!jsonMatch) {
+        throw new Error('No JSON found in response')
+      }
+      parsed = JSON.parse(jsonMatch[0])
+    } catch (e) {
+      console.error('[suggest-charts] Failed to parse AI response:', text)
+      // Return empty suggestions on parse error
+      return Response.json({
+        suggestions: [],
+        analyzedText: textToAnalyze.substring(0, 100),
+        detectedData: 'Failed to parse AI response',
+        hasData: false,
+      } satisfies SuggestChartsResponse)
+    }
+
+    // Validate response structure
+    if (!parsed.suggestions || !Array.isArray(parsed.suggestions)) {
+      parsed.suggestions = []
+    }
+
+    // Ensure exactly 3 suggestions when data exists
+    if (parsed.hasData && parsed.suggestions.length !== 3) {
+      parsed.suggestions = parsed.suggestions.slice(0, 3)
+    }
+
+    // Validate each suggestion has required fields
+    parsed.suggestions = parsed.suggestions.filter(s =>
+      s.type && s.title && s.data && Array.isArray(s.data) && s.data.length >= 2
+    )
+
+    // Track usage
+    await trackFeatureUsage(userId, 'ai', 'suggest-charts', 1)
+
+    return Response.json(parsed satisfies SuggestChartsResponse)
+
+  } catch (error) {
+    console.error('[suggest-charts] Error:', error)
+    return Response.json({
+      error: 'Failed to generate chart suggestions',
+      suggestions: [],
+      analyzedText: textToAnalyze.substring(0, 100),
+      detectedData: 'Error occurred during analysis',
+      hasData: false,
+    } satisfies SuggestChartsResponse, { status: 500 })
+  }
+}