running finally..

src/main/java/group/goforward/ballistic/controllers/CategoryController.java

@@ -0,0 +1,34 @@
+package group.goforward.ballistic.controllers;
+
+import group.goforward.ballistic.repos.PartCategoryRepository;
+import group.goforward.ballistic.web.dto.admin.PartCategoryDto;
+import org.springframework.web.bind.annotation.*;
+
+import java.util.List;
+
+@RestController
+@RequestMapping("/api/categories")
+@CrossOrigin // you can tighten origins later
+public class CategoryController {
+
+    private final PartCategoryRepository partCategories;
+
+    public CategoryController(PartCategoryRepository partCategories) {
+        this.partCategories = partCategories;
+    }
+
+    @GetMapping
+    public List<PartCategoryDto> list() {
+        return partCategories.findAllByOrderByGroupNameAscSortOrderAscNameAsc()
+                .stream()
+                .map(pc -> new PartCategoryDto(
+                        pc.getId(),
+                        pc.getSlug(),
+                        pc.getName(),
+                        pc.getDescription(),
+                        pc.getGroupName(),
+                        pc.getSortOrder()
+                ))
+                .toList();
+    }
+}

src/main/java/group/goforward/ballistic/model/CategoryMapping.java

@@ -0,0 +1,98 @@
+// src/main/java/group/goforward/ballistic/model/CategoryMapping.java
+package group.goforward.ballistic.model;
+
+import jakarta.persistence.*;
+import java.time.OffsetDateTime;
+
+@Entity
+@Table(name = "category_mappings")
+public class CategoryMapping {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    @Column(name = "id", nullable = false)
+    private Integer id;
+
+    @ManyToOne(fetch = FetchType.LAZY, optional = false)
+    @JoinColumn(name = "merchant_id", nullable = false)
+    private Merchant merchant;
+
+    @Column(name = "raw_category_path", nullable = false)
+    private String rawCategoryPath;
+
+    @ManyToOne(fetch = FetchType.LAZY)
+    @JoinColumn(name = "part_category_id")
+    private PartCategory partCategory;
+
+    @Column(name = "created_at", nullable = false)
+    private OffsetDateTime createdAt = OffsetDateTime.now();
+
+    @Column(name = "updated_at", nullable = false)
+    private OffsetDateTime updatedAt = OffsetDateTime.now();
+
+    @PrePersist
+    public void onCreate() {
+        OffsetDateTime now = OffsetDateTime.now();
+        if (createdAt == null) {
+            createdAt = now;
+        }
+        if (updatedAt == null) {
+            updatedAt = now;
+        }
+    }
+
+    @PreUpdate
+    public void onUpdate() {
+        this.updatedAt = OffsetDateTime.now();
+    }
+
+    // --- getters & setters ---
+
+    public Integer getId() {
+        return id;
+    }
+
+    public void setId(Integer id) {
+        this.id = id;
+    }
+
+    public Merchant getMerchant() {
+        return merchant;
+    }
+
+    public void setMerchant(Merchant merchant) {
+        this.merchant = merchant;
+    }
+
+    public String getRawCategoryPath() {
+        return rawCategoryPath;
+    }
+
+    public void setRawCategoryPath(String rawCategoryPath) {
+        this.rawCategoryPath = rawCategoryPath;
+    }
+
+    public PartCategory getPartCategory() {
+        return partCategory;
+    }
+
+    public void setPartCategory(PartCategory partCategory) {
+        this.partCategory = partCategory;
+    }
+
+    public OffsetDateTime getCreatedAt() {
+        return createdAt;
+    }
+
+    public void setCreatedAt(OffsetDateTime createdAt) {
+        this.createdAt = createdAt;
+    }
+
+    public OffsetDateTime getUpdatedAt() {
+        return updatedAt;
+    }
+
+    public void setUpdatedAt(OffsetDateTime updatedAt) {
+        this.updatedAt = updatedAt;
+    }
+}

src/main/java/group/goforward/ballistic/web/dto/admin/MerchantCategoryMappingDto.java

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+// src/main/java/group/goforward/ballistic/web/dto/admin/MerchantCategoryMappingDto.java
+package group.goforward.ballistic.web.dto.admin;
+
+public record MerchantCategoryMappingDto(
+        Integer id,
+        Integer merchantId,
+        String merchantName,
+        String rawCategoryPath,
+        Integer partCategoryId,
+        String partCategoryName
+) {}

src/main/java/group/goforward/ballistic/web/dto/admin/SimpleMerchantDto.java

@@ -0,0 +1,6 @@
+package group.goforward.ballistic.web.dto.admin;
+
+public record SimpleMerchantDto(
+        Integer id,
+        String name
+) { }

src/main/java/group/goforward/ballistic/web/dto/admin/UpdateMerchantCategoryMappingRequest.java

@@ -0,0 +1,5 @@
+package group.goforward.ballistic.web.dto.admin;
+
+public record UpdateMerchantCategoryMappingRequest(
+        Integer partCategoryId
+) {}