diff --git a/memento-note/app/api/ai/suggest-charts/route.ts b/memento-note/app/api/ai/suggest-charts/route.ts
index 21874bf..b501331 100644
--- a/memento-note/app/api/ai/suggest-charts/route.ts
+++ b/memento-note/app/api/ai/suggest-charts/route.ts
@@ -32,21 +32,28 @@ interface SuggestChartsResponse {
 }
 
 export async function POST(req: Request) {
+  console.log('[suggest-charts] ===== REQUEST START =====')
+
   // 1. Auth check
   const session = await auth()
   if (!session?.user?.id) {
+    console.error('[suggest-charts] NO SESSION')
     return new Response('Unauthorized', { status: 401 })
   }
   const userId = session.user.id
+  console.log('[suggest-charts] userId:', userId)
 
   // 1.5 Quota check
   try {
     const sysConfigEarly = await getSystemConfig()
     const { usedByok: willUseByok } = await willUseByokForLane('suggest-charts', sysConfigEarly, userId)
+    console.log('[suggest-charts] BYOK:', willUseByok)
     if (!willUseByok) {
       await checkEntitlementOrThrow(userId, 'suggest_charts')
+      console.log('[suggest-charts] Quota OK')
     }
   } catch (err) {
+    console.error('[suggest-charts] QUOTA ERROR:', err)
     if (err instanceof QuotaExceededError) {
       return Response.json(err.toJSON(), { status: 402 })
     }
@@ -54,10 +61,24 @@ export async function POST(req: Request) {
   }
 
   // 2. Parse request body
-  const body = await req.json() as SuggestChartsRequest
+  let body: SuggestChartsRequest
+  try {
+    body = await req.json()
+  } catch (e) {
+    console.error('[suggest-charts] INVALID JSON:', e)
+    return Response.json({
+      error: 'Invalid request',
+      suggestions: [],
+      analyzedText: '',
+      detectedData: '',
+      hasData: false,
+    } satisfies SuggestChartsResponse, { status: 400 })
+  }
   const { content, selection, noteId } = body
+  console.log('[suggest-charts] contentLen:', content?.length, 'selectionLen:', selection?.length)
 
   if (!content || content.trim().length === 0) {
+    console.error('[suggest-charts] EMPTY CONTENT')
     return Response.json({
       error: 'Content is required',
       suggestions: [],
@@ -68,10 +89,26 @@ export async function POST(req: Request) {
   }
 
   const textToAnalyze = selection && selection.trim() ? selection.trim() : content.trim()
+  console.log('[suggest-charts] analyzeLen:', textToAnalyze.length, 'preview:', textToAnalyze.substring(0, 100))
 
   // 3. Build AI context
-  const sysConfig = await getSystemConfig()
-  const { provider, model, timingInfo } = await resolveAiRouteWithTiming('suggest-charts', sysConfig)
+  let sysConfig, provider, model
+  try {
+    sysConfig = await getSystemConfig()
+    const result = await resolveAiRouteWithTiming('suggest-charts', sysConfig)
+    provider = result.provider
+    model = result.model
+    console.log('[suggest-charts] AI model:', model)
+  } catch (e) {
+    console.error('[suggest-charts] AI ROUTE ERROR:', e)
+    return Response.json({
+      error: 'AI service unavailable: ' + (e instanceof Error ? e.message : String(e)),
+      suggestions: [],
+      analyzedText: textToAnalyze.substring(0, 100),
+      detectedData: '',
+      hasData: false,
+    } satisfies SuggestChartsResponse, { status: 500 })
+  }
 
   try {
     // 4. Call AI to analyze and suggest - direct JSON response (no tool)
@@ -206,12 +243,15 @@ Response format (COPY this structure):
     return Response.json(parsed satisfies SuggestChartsResponse)
 
   } catch (error) {
-    console.error('[suggest-charts] Error:', error)
+    console.error('[suggest-charts] ===== MAIN ERROR =====')
+    console.error('[suggest-charts] Error name:', error instanceof Error ? error.name : typeof error)
+    console.error('[suggest-charts] Error message:', error instanceof Error ? error.message : String(error))
+    console.error('[suggest-charts] Error stack:', error instanceof Error ? error.stack : 'no stack')
     return Response.json({
-      error: 'Failed to generate chart suggestions',
+      error: 'Failed: ' + (error instanceof Error ? error.message : String(error)),
       suggestions: [],
-      analyzedText: textToAnalyze.substring(0, 100),
-      detectedData: 'Error occurred during analysis',
+      analyzedText: textToAnalyze?.substring(0, 100) || '',
+      detectedData: 'Error occurred',
       hasData: false,
     } satisfies SuggestChartsResponse, { status: 500 })
   }
diff --git a/memento-note/components/chart-suggestions-dialog.tsx b/memento-note/components/chart-suggestions-dialog.tsx
index 6bbad4e..52978f6 100644
--- a/memento-note/components/chart-suggestions-dialog.tsx
+++ b/memento-note/components/chart-suggestions-dialog.tsx
@@ -176,7 +176,14 @@ export function ChartSuggestionsDialog({
               <div className="text-center max-w-md">
                 <AlertCircle className="w-12 h-12 mx-auto mb-4 text-destructive" />
                 <h3 className="text-lg font-semibold mb-2">Error</h3>
-                <p className="text-muted-foreground">{response.error}</p>
+                <p className="text-sm text-muted-foreground mb-2">{response.error}</p>
+                <details className="text-left text-xs text-muted-foreground mt-4">
+                  <summary className="cursor-pointer hover:text-foreground">Debug info</summary>
+                  <pre className="mt-2 bg-muted p-2 rounded overflow-auto max-h-32">
+                    analyzedText: {response.analyzedText}
+                    {'\n'}detectedData: {response.detectedData}
+                  </pre>
+                </details>
               </div>
             </div>
           ) : !response?.hasData ? (