feat: add flexible region matching to servers API

- Add shared buildFlexibleRegionConditions() in utils.ts
- Add COUNTRY_NAME_TO_REGIONS mapping for country/city expansion
- Update servers.ts to use flexible region matching (korea, tokyo, japan, etc.)
- Update recommend.ts to use shared function (remove duplicate code)
- Fix servers GROUP BY to show all regions (it.id, r.id)
- Update CLAUDE.md with single-line curl examples

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

src/handlers/recommend.ts

@@ -28,7 +28,8 @@ import {
   isValidTechSpec,
   isValidAIRecommendation,
   sanitizeForAIPrompt,
-  DEFAULT_REGION_FILTER_SQL
+  DEFAULT_REGION_FILTER_SQL,
+  buildFlexibleRegionConditions
 } from '../utils';
 
 export async function handleRecommend(
@@ -384,52 +385,11 @@ async function queryCandidateServers(
     }
   }
 
-  // Country name to code mapping for common names
-  // Note: Use specific city names to avoid LIKE pattern collisions (e.g., 'de' matches 'Delhi')
-  const countryNameToCode: 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'],
-    'india': ['mumbai', 'delhi', 'bangalore', 'hyderabad', 'ap-south-1'],
-    'australia': ['sydney', 'melbourne', 'ap-southeast-2'],
-    'germany': ['frankfurt', 'nuremberg', 'falkenstein', 'eu-central-1'],
-    'usa': ['us-east', 'us-west', 'virginia', 'oregon', 'ohio'],
-    'united states': ['us-east', 'us-west', 'virginia', 'oregon', 'ohio'],
-    'uk': ['london', 'manchester', 'eu-west-2'],
-    'united kingdom': ['london', 'manchester', 'eu-west-2'],
-    'netherlands': ['amsterdam', 'eu-west-1'],
-    'france': ['paris', 'eu-west-3'],
-    'hong kong': ['hong kong', 'ap-east-1'],
-    'taiwan': ['taipei', 'ap-northeast-1'],
-    'brazil': ['sao paulo', 'sa-east-1'],
-    'canada': ['montreal', 'toronto', 'ca-central-1'],
-  };
-
   // Flexible region matching: region_code, region_name, or country_code
   if (req.region_preference && req.region_preference.length > 0) {
-    // User specified region → filter to that region only
-    const regionConditions: string[] = [];
-    for (const region of req.region_preference) {
-      const lowerRegion = region.toLowerCase();
-
-      // Expand country names to their codes/cities
-      const expandedRegions = countryNameToCode[lowerRegion] || [lowerRegion];
-      const allRegions = [lowerRegion, ...expandedRegions];
-
-      for (const r of allRegions) {
-        const escapedRegion = escapeLikePattern(r);
-        regionConditions.push(`(
-          LOWER(r.region_code) = ? OR
-          LOWER(r.region_code) LIKE ? ESCAPE '\\' OR
-          LOWER(r.region_name) LIKE ? ESCAPE '\\' OR
-          LOWER(r.country_code) = ?
-        )`);
-        params.push(r, `%${escapedRegion}%`, `%${escapedRegion}%`, r);
-      }
-    }
-    query += ` AND (${regionConditions.join(' OR ')})`;
+    const { conditions, params: regionParams } = buildFlexibleRegionConditions(req.region_preference);
+    query += ` AND (${conditions.join(' OR ')})`;
+    params.push(...regionParams);
   } else {
     // No region specified → default to Seoul/Tokyo/Osaka/Singapore
     query += ` AND ${DEFAULT_REGION_FILTER_SQL}`;

src/handlers/servers.ts

@@ -3,7 +3,7 @@
  */
 
 import type { Env } from '../types';
-import { jsonResponse, isValidServer, DEFAULT_REGION_FILTER_SQL } from '../utils';
+import { jsonResponse, isValidServer, DEFAULT_REGION_FILTER_SQL, buildFlexibleRegionConditions } from '../utils';
 
 /**
  * GET /api/servers - Server list with filtering
@@ -42,9 +42,9 @@ export async function handleGetServers(
         it.instance_family,
         it.gpu_count,
         it.gpu_type,
-        MIN(pr.monthly_price) as monthly_price,
-        MIN(r.region_name) as region_name,
-        MIN(r.region_code) as region_code
+        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
@@ -79,11 +79,13 @@ export async function handleGetServers(
     }
 
     if (region) {
-      query += ` AND r.region_code = ?`;
-      params.push(region);
+      // Flexible region matching: supports country names, codes, city names
+      const { conditions, params: regionParams } = buildFlexibleRegionConditions([region]);
+      query += ` AND (${conditions.join(' OR ')})`;
+      params.push(...regionParams);
     }
 
-    query += ` GROUP BY it.id ORDER BY MIN(pr.monthly_price) ASC LIMIT 100`;
+    query += ` GROUP BY it.id, r.id ORDER BY pr.monthly_price ASC LIMIT 100`;
 
     const result = await env.DB.prepare(query).bind(...params).all();
 

src/utils.ts

@@ -138,6 +138,59 @@ export function escapeLikePattern(pattern: string): string {
   return pattern.replace(/[%_\\]/g, '\\$&');
 }
 
+/**
+ * Country name to region code/city mapping for flexible region matching
+ * Note: Use specific city names to avoid LIKE pattern collisions (e.g., 'de' matches 'Delhi')
+ */
+export 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'],
+};
+
+/**
+ * Build flexible region matching SQL conditions and parameters
+ */
+export function buildFlexibleRegionConditions(
+  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(r.region_code) = ? OR
+        LOWER(r.region_code) LIKE ? ESCAPE '\\' OR
+        LOWER(r.region_name) LIKE ? ESCAPE '\\' OR
+        LOWER(r.country_code) = ?
+      )`);
+      params.push(r, `%${escapedRegion}%`, `%${escapedRegion}%`, r);
+    }
+  }
+
+  return { conditions, params };
+}
+
 /**
  * Type guard to validate Server object structure
  */