feat: migrate pricing from legacy tables to anvil_pricing

- Replace pricing/instance_types/providers/regions with anvil_* tables
- Add real-time USD→KRW exchange rate conversion (open.er-api.com)
- Korean users (lang=ko) see KRW prices, others see USD
- Remove provider_filter parameter (now single provider: Anvil)
- Add ExchangeRateCache interface with 1-hour KV caching
- Update CLAUDE.md with new table structure and exchange rate docs

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/config.ts

@@ -90,7 +90,6 @@ export const i18n: Record<string, {
       traffic_pattern: "(optional) 'steady' | 'spiky' | 'growing'",
       region_preference: "(optional) string[] - e.g. ['korea', 'japan']",
       budget_limit: "(optional) number - max monthly USD",
-      provider_filter: "(optional) string[] - e.g. ['linode', 'vultr']",
       lang: "(optional) 'en' | 'zh' | 'ja' | 'ko' - response language"
     },
     example: {
@@ -110,7 +109,6 @@ export const i18n: Record<string, {
       traffic_pattern: "(可选) 'steady' | 'spiky' | 'growing'",
       region_preference: "(可选) string[] - 例如 ['korea', 'japan']",
       budget_limit: "(可选) number - 每月最高预算(美元)",
-      provider_filter: "(可选) string[] - 例如 ['linode', 'vultr']",
       lang: "(可选) 'en' | 'zh' | 'ja' | 'ko' - 响应语言"
     },
     example: {
@@ -130,7 +128,6 @@ export const i18n: Record<string, {
       traffic_pattern: "(任意) 'steady' | 'spiky' | 'growing'",
       region_preference: "(任意) string[] - 例: ['korea', 'japan']",
       budget_limit: "(任意) number - 月額予算上限(USD)",
-      provider_filter: "(任意) string[] - 例: ['linode', 'vultr']",
       lang: "(任意) 'en' | 'zh' | 'ja' | 'ko' - 応答言語"
     },
     example: {
@@ -150,7 +147,6 @@ export const i18n: Record<string, {
       traffic_pattern: "(선택) 'steady' | 'spiky' | 'growing'",
       region_preference: "(선택) string[] - 예: ['korea', 'japan']",
       budget_limit: "(선택) number - 월 예산 한도(원화, KRW)",
-      provider_filter: "(선택) string[] - 예: ['linode', 'vultr']",
       lang: "(선택) 'en' | 'zh' | 'ja' | 'ko' - 응답 언어"
     },
     example: {

src/handlers/recommend.ts

@@ -29,8 +29,7 @@ import {
   isValidTechSpec,
   isValidAIRecommendation,
   sanitizeForAIPrompt,
-  DEFAULT_REGION_FILTER_SQL,
-  buildFlexibleRegionConditions
+  getExchangeRate
 } from '../utils';
 
 export async function handleRecommend(
@@ -77,7 +76,6 @@ export async function handleRecommend(
       traffic_pattern: body.traffic_pattern,
       has_region_pref: !!body.region_preference,
       has_budget: !!body.budget_limit,
-      has_provider_filter: !!body.provider_filter,
       lang: lang,
     });
 
@@ -231,7 +229,7 @@ export async function handleRecommend(
 
     // Phase 2: Query candidate servers and VPS benchmarks in parallel
     const [candidates, vpsBenchmarks] = await Promise.all([
-      queryCandidateServers(env.DB, body, minMemoryMb, minVcpu, bandwidthEstimate, lang),
+      queryCandidateServers(env.DB, env, body, minMemoryMb, minVcpu, bandwidthEstimate, lang),
       queryVPSBenchmarksBatch(env.DB, estimatedCores, estimatedMemory, defaultProviders).catch((err: unknown) => {
         const message = err instanceof Error ? err.message : String(err);
         console.warn('[Recommend] VPS benchmarks unavailable:', message);
@@ -312,104 +310,81 @@ export async function handleRecommend(
 }
 async function queryCandidateServers(
   db: D1Database,
+  env: Env,
   req: RecommendRequest,
   minMemoryMb?: number,
   minVcpu?: number,
   bandwidthEstimate?: BandwidthEstimate,
   lang: string = 'en'
 ): Promise<Server[]> {
-  // Select price column based on language
-  // Korean → monthly_price_krw (KRW), Others → monthly_price_retail (1.21x USD)
-  const priceColumn = lang === 'ko' ? 'pr.monthly_price_krw' : 'pr.monthly_price_retail';
+  // Get exchange rate for KRW display (Korean users)
+  const exchangeRate = lang === 'ko' ? await getExchangeRate(env) : 1;
   const currency = lang === 'ko' ? 'KRW' : 'USD';
 
-  // Check if region preference is specified
-  const hasRegionPref = req.region_preference && req.region_preference.length > 0;
-
+  // Build query using anvil_* tables
+  // anvil_pricing.monthly_price is stored in USD
   let query = `
     SELECT
-      it.id,
-      p.display_name as provider_name,
-      it.instance_id,
-      it.instance_name,
-      it.vcpu,
-      it.memory_mb,
-      ROUND(it.memory_mb / 1024.0, 1) as memory_gb,
-      it.storage_gb,
-      it.network_speed_gbps,
-      it.instance_family,
-      it.gpu_count,
-      it.gpu_type,
-      MIN(${priceColumn}) as monthly_price,
-      r.region_name as region_name,
-      r.region_code as region_code,
-      r.country_code as country_code
-    FROM instance_types it
-    JOIN providers p ON it.provider_id = p.id
-    JOIN pricing pr ON pr.instance_type_id = it.id
-    JOIN regions r ON pr.region_id = r.id
-    WHERE LOWER(p.name) IN ('linode', 'vultr')  -- Linode, Vultr only
+      ai.id,
+      'Anvil' as provider_name,
+      ai.name as instance_id,
+      ai.display_name as instance_name,
+      ai.vcpus as vcpu,
+      CAST(ai.memory_gb * 1024 AS INTEGER) as memory_mb,
+      ai.memory_gb,
+      ai.disk_gb as storage_gb,
+      ai.network_gbps as network_speed_gbps,
+      ai.category as instance_family,
+      CASE WHEN ai.gpu_model IS NOT NULL THEN 1 ELSE 0 END as gpu_count,
+      ai.gpu_model as gpu_type,
+      ap.monthly_price as monthly_price_usd,
+      ar.display_name as region_name,
+      ar.name as region_code,
+      ar.country_code
+    FROM anvil_instances ai
+    JOIN anvil_pricing ap ON ap.anvil_instance_id = ai.id
+    JOIN anvil_regions ar ON ap.anvil_region_id = ar.id
+    WHERE ai.active = 1 AND ar.active = 1
   `;
 
   const params: (string | number)[] = [];
 
+  // Filter by budget limit (convert to USD for comparison)
   if (req.budget_limit) {
-    // Use same price column as display for budget filtering
-    query += ` AND ${priceColumn} <= ?`;
-    params.push(req.budget_limit);
+    const budgetUsd = lang === 'ko' ? req.budget_limit / exchangeRate : req.budget_limit;
+    query += ` AND ap.monthly_price <= ?`;
+    params.push(budgetUsd);
   }
 
   // Filter by minimum memory requirement (from tech specs)
+  // Note: anvil_instances uses memory_gb, so convert minMemoryMb to GB
   if (minMemoryMb && minMemoryMb > 0) {
-    query += ` AND it.memory_mb >= ?`;
-    params.push(minMemoryMb);
+    const minMemoryGb = minMemoryMb / 1024;
+    query += ` AND ai.memory_gb >= ?`;
+    params.push(minMemoryGb);
     console.log(`[Candidates] Filtering by minimum memory: ${minMemoryMb}MB (${(minMemoryMb/1024).toFixed(1)}GB)`);
   }
 
   // Filter by minimum vCPU requirement (from expected users + tech specs)
   if (minVcpu && minVcpu > 0) {
-    query += ` AND it.vcpu >= ?`;
+    query += ` AND ai.vcpus >= ?`;
     params.push(minVcpu);
     console.log(`[Candidates] Filtering by minimum vCPU: ${minVcpu}`);
   }
 
-  // Provider preference based on bandwidth requirements (no hard filtering to avoid empty results)
-  // Heavy/Very heavy bandwidth → Prefer Linode (better bandwidth allowance), but allow all providers
-  // AI prompt will warn about bandwidth costs for non-Linode providers
-  if (bandwidthEstimate) {
-    if (bandwidthEstimate.category === 'very_heavy') {
-      // >6TB/month: Strongly prefer Linode, but don't exclude others (Linode may not be available in all regions)
-      console.log(`[Candidates] Very heavy bandwidth (${bandwidthEstimate.monthly_tb}TB/month): Linode strongly preferred, all providers included`);
-    } else if (bandwidthEstimate.category === 'heavy') {
-      // 2-6TB/month: Prefer Linode
-      console.log(`[Candidates] Heavy bandwidth (${bandwidthEstimate.monthly_tb}TB/month): Linode preferred`);
-    }
-  }
-
-  // Flexible region matching: region_code, region_name, or country_code
+  // Flexible region matching using anvil_regions table
+  // r.* aliases need to change to ar.* for anvil_regions
   if (req.region_preference && req.region_preference.length > 0) {
-    const { conditions, params: regionParams } = buildFlexibleRegionConditions(req.region_preference);
+    const { conditions, params: regionParams } = buildFlexibleRegionConditionsAnvil(req.region_preference);
     query += ` AND (${conditions.join(' OR ')})`;
     params.push(...regionParams);
   } else {
-    // No region specified → default to Seoul/Tokyo/Osaka/Singapore
-    query += ` AND ${DEFAULT_REGION_FILTER_SQL}`;
+    // No region specified → default to Seoul/Tokyo/Singapore
+    query += ` AND ${DEFAULT_ANVIL_REGION_FILTER_SQL}`;
   }
 
-  // Filter by provider if specified
-  if (req.provider_filter && req.provider_filter.length > 0) {
-    const placeholders = req.provider_filter.map(() => '?').join(',');
-    query += ` AND (p.name IN (${placeholders}) OR p.display_name IN (${placeholders}))`;
-    params.push(...req.provider_filter, ...req.provider_filter);
-  }
-
-  // Group by instance + region to show each server per region
-  // For heavy/very_heavy bandwidth, prioritize Linode due to generous bandwidth allowance
-  const isHighBandwidth = bandwidthEstimate?.category === 'heavy' || bandwidthEstimate?.category === 'very_heavy';
-  const orderByClause = isHighBandwidth
-    ? `ORDER BY CASE WHEN LOWER(p.name) = 'linode' THEN 0 ELSE 1 END, monthly_price ASC`
-    : `ORDER BY monthly_price ASC`;
-  query += ` GROUP BY it.id, r.id ${orderByClause} LIMIT 50`;
+  // Order by price
+  query += ` ORDER BY ap.monthly_price ASC LIMIT 50`;
 
   const result = await db.prepare(query).bind(...params).all();
 
@@ -417,13 +392,22 @@ async function queryCandidateServers(
     throw new Error('Failed to query candidate servers');
   }
 
-  // Add currency to each result and validate with type guard
+  // Convert USD prices to display currency and validate
   const serversWithCurrency = (result.results as unknown[]).map(server => {
     if (typeof server === 'object' && server !== null) {
-      return { ...server, currency };
+      const s = server as Record<string, unknown>;
+      const priceUsd = s.monthly_price_usd as number;
+      // Convert to KRW if Korean, otherwise keep USD
+      const displayPrice = lang === 'ko' ? Math.round(priceUsd * exchangeRate) : priceUsd;
+      return {
+        ...s,
+        monthly_price: displayPrice,
+        currency
+      };
     }
     return server;
   });
+
   const validServers = serversWithCurrency.filter(isValidServer);
   const invalidCount = result.results.length - validServers.length;
   if (invalidCount > 0) {
@@ -432,6 +416,80 @@ async function queryCandidateServers(
   return validServers;
 }
 
+/**
+ * Default region filter SQL for anvil_regions (when no region is specified)
+ */
+const DEFAULT_ANVIL_REGION_FILTER_SQL = `(
+  -- Korea (Seoul)
+  ar.name IN ('icn', 'ap-northeast-2') OR
+  LOWER(ar.display_name) LIKE '%seoul%' OR
+  -- Japan (Tokyo, Osaka)
+  ar.name IN ('nrt', 'itm', 'ap-northeast-1', 'ap-northeast-3') OR
+  LOWER(ar.name) LIKE '%tyo%' OR
+  LOWER(ar.name) LIKE '%osa%' OR
+  LOWER(ar.display_name) LIKE '%tokyo%' OR
+  LOWER(ar.display_name) LIKE '%osaka%' OR
+  -- Singapore
+  ar.name IN ('sgp', 'ap-southeast-1') OR
+  LOWER(ar.name) LIKE '%sin%' OR
+  LOWER(ar.name) LIKE '%sgp%' OR
+  LOWER(ar.display_name) LIKE '%singapore%'
+)`;
+
+/**
+ * Build flexible region matching SQL conditions for anvil_regions
+ */
+function buildFlexibleRegionConditionsAnvil(
+  regions: string[]
+): { conditions: string[]; params: (string | number)[] } {
+  const conditions: string[] = [];
+  const params: (string | number)[] = [];
+
+  // Country name to region mapping
+  const COUNTRY_NAME_TO_REGIONS: Record<string, string[]> = {
+    'korea': ['seoul', 'koreacentral', 'kr', 'ap-northeast-2'],
+    'south korea': ['seoul', 'koreacentral', 'kr', 'ap-northeast-2'],
+    'japan': ['tokyo', 'osaka', 'ap-northeast-1', 'ap-northeast-3'],
+    'singapore': ['singapore', 'ap-southeast-1'],
+    'indonesia': ['jakarta', 'ap-southeast-3'],
+    'australia': ['sydney', 'melbourne', 'au-east', 'ap-southeast-2'],
+    'india': ['mumbai', 'delhi', 'chennai', 'ap-south'],
+    'usa': ['us-east', 'us-west', 'us-central', 'america'],
+    'us': ['us-east', 'us-west', 'us-central', 'america'],
+    'united states': ['us-east', 'us-west', 'us-central', 'america'],
+    'uk': ['london', 'uk-south', 'eu-west-2'],
+    'united kingdom': ['london', 'uk-south', 'eu-west-2'],
+    'germany': ['frankfurt', 'eu-central', 'eu-west-3'],
+    'france': ['paris', 'eu-west-3'],
+    'netherlands': ['amsterdam', 'eu-west-1'],
+    'brazil': ['sao paulo', 'sa-east'],
+    'canada': ['toronto', 'montreal', 'ca-central'],
+  };
+
+  const escapeLikePattern = (pattern: string): string => {
+    return pattern.replace(/[%_\\]/g, '\\$&');
+  };
+
+  for (const region of regions) {
+    const lowerRegion = region.toLowerCase();
+    const expandedRegions = COUNTRY_NAME_TO_REGIONS[lowerRegion] || [lowerRegion];
+    const allRegions = [lowerRegion, ...expandedRegions];
+
+    for (const r of allRegions) {
+      const escapedRegion = escapeLikePattern(r);
+      conditions.push(`(
+        LOWER(ar.name) = ? OR
+        LOWER(ar.name) LIKE ? ESCAPE '\\' OR
+        LOWER(ar.display_name) LIKE ? ESCAPE '\\' OR
+        LOWER(ar.country_code) = ?
+      )`);
+      params.push(r, `%${escapedRegion}%`, `%${escapedRegion}%`, r);
+    }
+  }
+
+  return { conditions, params };
+}
+
 /**
  * Query relevant benchmark data for tech stack
  */

src/handlers/servers.ts

@@ -3,10 +3,90 @@
  */
 
 import type { Env } from '../types';
-import { jsonResponse, isValidServer, DEFAULT_REGION_FILTER_SQL, buildFlexibleRegionConditions } from '../utils';
+import { jsonResponse, isValidServer } from '../utils';
+
+/**
+ * Default region filter SQL for anvil_regions (when no region is specified)
+ */
+const DEFAULT_ANVIL_REGION_FILTER_SQL = `(
+  -- Korea (Seoul)
+  ar.name IN ('icn', 'ap-northeast-2') OR
+  LOWER(ar.display_name) LIKE '%seoul%' OR
+  -- Japan (Tokyo, Osaka)
+  ar.name IN ('nrt', 'itm', 'ap-northeast-1', 'ap-northeast-3') OR
+  LOWER(ar.name) LIKE '%tyo%' OR
+  LOWER(ar.name) LIKE '%osa%' OR
+  LOWER(ar.display_name) LIKE '%tokyo%' OR
+  LOWER(ar.display_name) LIKE '%osaka%' OR
+  -- Singapore
+  ar.name IN ('sgp', 'ap-southeast-1') OR
+  LOWER(ar.name) LIKE '%sin%' OR
+  LOWER(ar.name) LIKE '%sgp%' OR
+  LOWER(ar.display_name) LIKE '%singapore%'
+)`;
+
+/**
+ * Country name to region code/city mapping for flexible region matching
+ */
+const COUNTRY_NAME_TO_REGIONS: Record<string, string[]> = {
+  'korea': ['seoul', 'koreacentral', 'kr', 'ap-northeast-2'],
+  'south korea': ['seoul', 'koreacentral', 'kr', 'ap-northeast-2'],
+  'japan': ['tokyo', 'osaka', 'ap-northeast-1', 'ap-northeast-3'],
+  'singapore': ['singapore', 'ap-southeast-1'],
+  'indonesia': ['jakarta', 'ap-southeast-3'],
+  'australia': ['sydney', 'melbourne', 'au-east', 'ap-southeast-2'],
+  'india': ['mumbai', 'delhi', 'chennai', 'ap-south'],
+  'usa': ['us-east', 'us-west', 'us-central', 'america'],
+  'us': ['us-east', 'us-west', 'us-central', 'america'],
+  'united states': ['us-east', 'us-west', 'us-central', 'america'],
+  'uk': ['london', 'uk-south', 'eu-west-2'],
+  'united kingdom': ['london', 'uk-south', 'eu-west-2'],
+  'germany': ['frankfurt', 'eu-central', 'eu-west-3'],
+  'france': ['paris', 'eu-west-3'],
+  'netherlands': ['amsterdam', 'eu-west-1'],
+  'brazil': ['sao paulo', 'sa-east'],
+  'canada': ['toronto', 'montreal', 'ca-central'],
+};
+
+/**
+ * Escape LIKE pattern special characters
+ */
+function escapeLikePattern(pattern: string): string {
+  return pattern.replace(/[%_\\]/g, '\\$&');
+}
+
+/**
+ * Build flexible region matching SQL conditions for anvil_regions
+ */
+function buildFlexibleRegionConditionsAnvil(
+  regions: string[]
+): { conditions: string[]; params: (string | number)[] } {
+  const conditions: string[] = [];
+  const params: (string | number)[] = [];
+
+  for (const region of regions) {
+    const lowerRegion = region.toLowerCase();
+    const expandedRegions = COUNTRY_NAME_TO_REGIONS[lowerRegion] || [lowerRegion];
+    const allRegions = [lowerRegion, ...expandedRegions];
+
+    for (const r of allRegions) {
+      const escapedRegion = escapeLikePattern(r);
+      conditions.push(`(
+        LOWER(ar.name) = ? OR
+        LOWER(ar.name) LIKE ? ESCAPE '\\' OR
+        LOWER(ar.display_name) LIKE ? ESCAPE '\\' OR
+        LOWER(ar.country_code) = ?
+      )`);
+      params.push(r, `%${escapedRegion}%`, `%${escapedRegion}%`, r);
+    }
+  }
+
+  return { conditions, params };
+}
 
 /**
  * GET /api/servers - Server list with filtering
+ * Uses anvil_* tables for pricing data
  */
 export async function handleGetServers(
   request: Request,
@@ -15,57 +95,49 @@ export async function handleGetServers(
 ): Promise<Response> {
   try {
     const url = new URL(request.url);
-    const provider = url.searchParams.get('provider');
     const minCpu = url.searchParams.get('minCpu');
     const minMemory = url.searchParams.get('minMemory');
     const region = url.searchParams.get('region');
 
     console.log('[GetServers] Query params:', {
-      provider,
       minCpu,
       minMemory,
       region,
     });
 
-    // Build SQL query dynamically
+    // Build SQL query using anvil_* tables
     let query = `
       SELECT
-        it.id,
-        p.display_name as provider_name,
-        it.instance_id,
-        it.instance_name,
-        it.vcpu,
-        it.memory_mb,
-        ROUND(it.memory_mb / 1024.0, 1) as memory_gb,
-        it.storage_gb,
-        it.network_speed_gbps,
-        it.instance_family,
-        it.gpu_count,
-        it.gpu_type,
-        pr.monthly_price,
-        r.region_name,
-        r.region_code
-      FROM instance_types it
-      JOIN providers p ON it.provider_id = p.id
-      JOIN pricing pr ON pr.instance_type_id = it.id
-      JOIN regions r ON pr.region_id = r.id
-      WHERE LOWER(p.name) IN ('linode', 'vultr')
-        AND ${DEFAULT_REGION_FILTER_SQL}
+        ai.id,
+        'Anvil' as provider_name,
+        ai.name as instance_id,
+        ai.display_name as instance_name,
+        ai.vcpus as vcpu,
+        CAST(ai.memory_gb * 1024 AS INTEGER) as memory_mb,
+        ai.memory_gb,
+        ai.disk_gb as storage_gb,
+        ai.network_gbps as network_speed_gbps,
+        ai.category as instance_family,
+        CASE WHEN ai.gpu_model IS NOT NULL THEN 1 ELSE 0 END as gpu_count,
+        ai.gpu_model as gpu_type,
+        ap.monthly_price,
+        ar.display_name as region_name,
+        ar.name as region_code
+      FROM anvil_instances ai
+      JOIN anvil_pricing ap ON ap.anvil_instance_id = ai.id
+      JOIN anvil_regions ar ON ap.anvil_region_id = ar.id
+      WHERE ai.active = 1 AND ar.active = 1
+        AND ${DEFAULT_ANVIL_REGION_FILTER_SQL}
     `;
 
     const params: (string | number)[] = [];
 
-    if (provider) {
-      query += ` AND p.name = ?`;
-      params.push(provider);
-    }
-
     if (minCpu) {
       const parsedCpu = parseInt(minCpu, 10);
       if (isNaN(parsedCpu)) {
         return jsonResponse({ error: 'Invalid minCpu parameter' }, 400, corsHeaders);
       }
-      query += ` AND it.vcpu >= ?`;
+      query += ` AND ai.vcpus >= ?`;
       params.push(parsedCpu);
     }
 
@@ -74,18 +146,19 @@ export async function handleGetServers(
       if (isNaN(parsedMemory)) {
         return jsonResponse({ error: 'Invalid minMemory parameter' }, 400, corsHeaders);
       }
-      query += ` AND it.memory_mb >= ?`;
-      params.push(parsedMemory * 1024);
+      // minMemory is in GB, anvil_instances stores memory_gb
+      query += ` AND ai.memory_gb >= ?`;
+      params.push(parsedMemory);
     }
 
     if (region) {
       // Flexible region matching: supports country names, codes, city names
-      const { conditions, params: regionParams } = buildFlexibleRegionConditions([region]);
+      const { conditions, params: regionParams } = buildFlexibleRegionConditionsAnvil([region]);
       query += ` AND (${conditions.join(' OR ')})`;
       params.push(...regionParams);
     }
 
-    query += ` GROUP BY it.id, r.id ORDER BY pr.monthly_price ASC LIMIT 100`;
+    query += ` ORDER BY ap.monthly_price ASC LIMIT 100`;
 
     const result = await env.DB.prepare(query).bind(...params).all();
 
@@ -93,8 +166,15 @@ export async function handleGetServers(
       throw new Error('Database query failed');
     }
 
-    // Validate each result with type guard
-    const servers = (result.results as unknown[]).filter(isValidServer);
+    // Add USD currency to each result and validate with type guard
+    const serversWithCurrency = (result.results as unknown[]).map(server => {
+      if (typeof server === 'object' && server !== null) {
+        return { ...server, currency: 'USD' };
+      }
+      return server;
+    });
+
+    const servers = serversWithCurrency.filter(isValidServer);
     const invalidCount = result.results.length - servers.length;
     if (invalidCount > 0) {
       console.warn(`[GetServers] Filtered out ${invalidCount} invalid server records`);
@@ -106,7 +186,7 @@ export async function handleGetServers(
       {
         servers,
         count: servers.length,
-        filters: { provider, minCpu, minMemory, region },
+        filters: { minCpu, minMemory, region },
       },
       200,
       corsHeaders

src/types.ts

@@ -25,10 +25,14 @@ export interface RecommendRequest {
   traffic_pattern?: 'steady' | 'spiky' | 'growing';
   region_preference?: string[];
   budget_limit?: number;
-  provider_filter?: string[]; // Filter by specific providers (e.g., ["Linode", "Vultr"])
   lang?: 'en' | 'zh' | 'ja' | 'ko'; // Response language
 }
 
+export interface ExchangeRateCache {
+  rate: number;
+  timestamp: number;
+}
+
 export interface Server {
   id: number;
   provider_name: string;

src/utils.ts

@@ -12,7 +12,9 @@ import type {
   AIRecommendationResponse,
   UseCaseConfig,
   BandwidthEstimate,
-  BandwidthInfo
+  BandwidthInfo,
+  Env,
+  ExchangeRateCache
 } from './types';
 import { USE_CASE_CONFIGS, i18n, LIMITS } from './config';
 
@@ -96,12 +98,6 @@ export function generateCacheKey(req: RecommendRequest): string {
     parts.push(`budget:${req.budget_limit}`);
   }
 
-  if (req.provider_filter && req.provider_filter.length > 0) {
-    const sortedProviders = [...req.provider_filter].sort();
-    const sanitizedProviders = sortedProviders.map(sanitizeCacheValue).join(',');
-    parts.push(`prov:${sanitizedProviders}`);
-  }
-
   // Include language in cache key
   if (req.lang) {
     parts.push(`lang:${req.lang}`);
@@ -331,16 +327,6 @@ export function validateRecommendRequest(body: any, lang: string = 'en'): Valida
     invalidFields.push({ field: 'budget_limit', reason: 'must be a non-negative number' });
   }
 
-  if (body.provider_filter !== undefined) {
-    if (!Array.isArray(body.provider_filter)) {
-      invalidFields.push({ field: 'provider_filter', reason: 'must be an array' });
-    } else if (body.provider_filter.length > 10) {
-      invalidFields.push({ field: 'provider_filter', reason: 'must not exceed 10 items' });
-    } else if (!body.provider_filter.every((item: any) => typeof item === 'string')) {
-      invalidFields.push({ field: 'provider_filter', reason: 'all items must be strings' });
-    }
-  }
-
   // Validate lang field if provided
   if (body.lang !== undefined && !['en', 'zh', 'ja', 'ko'].includes(body.lang)) {
     invalidFields.push({ field: 'lang', reason: "must be one of: 'en', 'zh', 'ja', 'ko'" });
@@ -684,6 +670,74 @@ export function sanitizeForAIPrompt(input: string, maxLength: number = 200): str
   return sanitized.slice(0, maxLength);
 }
 
+/**
+ * Exchange rate constants
+ */
+const EXCHANGE_RATE_CACHE_KEY = 'exchange_rate:USD_KRW';
+const EXCHANGE_RATE_TTL_SECONDS = 3600; // 1 hour
+const EXCHANGE_RATE_FALLBACK = 1450; // Fallback KRW rate if API fails
+
+/**
+ * Get USD to KRW exchange rate with KV caching
+ * Uses open.er-api.com free API
+ */
+export async function getExchangeRate(env: Env): Promise<number> {
+  // Try to get cached rate from KV
+  if (env.CACHE) {
+    try {
+      const cached = await env.CACHE.get(EXCHANGE_RATE_CACHE_KEY);
+      if (cached) {
+        const data = JSON.parse(cached) as ExchangeRateCache;
+        console.log(`[ExchangeRate] Using cached rate: ${data.rate}`);
+        return data.rate;
+      }
+    } catch (error) {
+      console.warn('[ExchangeRate] Cache read error:', error);
+    }
+  }
+
+  // Fetch fresh rate from API
+  try {
+    const response = await fetch('https://open.er-api.com/v6/latest/USD', {
+      headers: { 'Accept': 'application/json' },
+    });
+
+    if (!response.ok) {
+      throw new Error(`API returned ${response.status}`);
+    }
+
+    const data = await response.json() as { rates?: { KRW?: number } };
+    const rate = data?.rates?.KRW;
+
+    if (!rate || typeof rate !== 'number' || rate < 1000 || rate > 2000) {
+      console.warn('[ExchangeRate] Invalid rate from API:', rate);
+      return EXCHANGE_RATE_FALLBACK;
+    }
+
+    console.log(`[ExchangeRate] Fetched fresh rate: ${rate}`);
+
+    // Cache the rate
+    if (env.CACHE) {
+      try {
+        const cacheData: ExchangeRateCache = {
+          rate,
+          timestamp: Date.now(),
+        };
+        await env.CACHE.put(EXCHANGE_RATE_CACHE_KEY, JSON.stringify(cacheData), {
+          expirationTtl: EXCHANGE_RATE_TTL_SECONDS,
+        });
+      } catch (error) {
+        console.warn('[ExchangeRate] Cache write error:', error);
+      }
+    }
+
+    return rate;
+  } catch (error) {
+    console.error('[ExchangeRate] API error:', error);
+    return EXCHANGE_RATE_FALLBACK;
+  }
+}
+
 // In-memory fallback for rate limiting when CACHE KV is unavailable
 const inMemoryRateLimit = new Map<string, { count: number; resetTime: number }>();