first implementation

backend/src/main/java/com/aiteacher/topic/TopicController.java

@@ -0,0 +1,35 @@
+package com.aiteacher.topic;
+
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.*;
+
+import java.util.List;
+import java.util.NoSuchElementException;
+
+@RestController
+@RequestMapping("/api/v1/topics")
+public class TopicController {
+
+    private final TopicConfigLoader topicConfigLoader;
+    private final TopicSummaryService topicSummaryService;
+
+    public TopicController(TopicConfigLoader topicConfigLoader,
+                           TopicSummaryService topicSummaryService) {
+        this.topicConfigLoader = topicConfigLoader;
+        this.topicSummaryService = topicSummaryService;
+    }
+
+    @GetMapping
+    public ResponseEntity<List<Topic>> list() {
+        return ResponseEntity.ok(topicConfigLoader.getAll());
+    }
+
+    @PostMapping("/{id}/summary")
+    public ResponseEntity<TopicSummaryResponse> generateSummary(@PathVariable String id) {
+        Topic topic = topicConfigLoader.findById(id)
+            .orElseThrow(() -> new NoSuchElementException("Topic not found."));
+
+        TopicSummaryResponse response = topicSummaryService.generateSummary(topic);
+        return ResponseEntity.ok(response);
+    }
+}