diff --git a/api-v3/src/inspection-findings/finding-catalog-merge.service.ts b/api-v3/src/inspection-findings/finding-catalog-merge.service.ts
new file mode 100644
index 0000000..9c4e36c
--- /dev/null
+++ b/api-v3/src/inspection-findings/finding-catalog-merge.service.ts
@@ -0,0 +1,268 @@
+import {
+  BadRequestException,
+  ConflictException,
+  Injectable,
+  NotFoundException,
+} from '@nestjs/common';
+import { DataSource, EntityManager } from 'typeorm';
+import { administrationAuditContext } from '../administration/common/administration-audit';
+import { AuditService } from '../audit/audit.service';
+import type { AuthPrincipal, RequestWithContext } from '../common/http/request-context';
+import { AuditAction } from '../database/entities';
+import type { MergeFindingCatalogItemDto } from './dto/merge-finding-catalog-item.dto';
+
+type CatalogItemRow = {
+  id: string;
+  categoryId: string;
+  categoryCode: string;
+  categoryName: string;
+  code: string;
+  sourceNumber: number;
+  title: string;
+  legalBasis: string | null;
+  glossary: string | null;
+  importNote: string | null;
+  suggestedSeverity: number | null;
+  revision: number;
+  isActive: boolean;
+};
+
+@Injectable()
+export class FindingCatalogMergeService {
+  constructor(
+    private readonly dataSource: DataSource,
+    private readonly audit: AuditService,
+  ) {}
+
+  async status(itemId: string) {
+    const requested = await this.load(this.dataSource.manager, itemId, false);
+    const canonicalId = await this.resolveCanonicalId(this.dataSource.manager, itemId);
+    const canonical = canonicalId === itemId
+      ? requested
+      : await this.load(this.dataSource.manager, canonicalId, false);
+    const aliases = await this.dataSource.query(`
+      WITH RECURSIVE aliases AS (
+        SELECT source_item_id,canonical_item_id,reason,merged_at,1 AS depth
+        FROM finding_catalog_item_merges WHERE canonical_item_id=$1::uuid
+        UNION ALL
+        SELECT merge_record.source_item_id,merge_record.canonical_item_id,
+          merge_record.reason,merge_record.merged_at,aliases.depth+1
+        FROM finding_catalog_item_merges merge_record
+        JOIN aliases ON merge_record.canonical_item_id=aliases.source_item_id
+        WHERE aliases.depth<32
+      )
+      SELECT alias.source_item_id AS id,item.code,item.title,alias.reason,
+        alias.merged_at AS "mergedAt",alias.depth
+      FROM aliases alias
+      JOIN finding_catalog_items item ON item.id=alias.source_item_id
+      ORDER BY alias.merged_at,alias.depth
+    `, [canonicalId]);
+    return {
+      requested,
+      isMerged: canonicalId !== itemId,
+      canonical,
+      aliases,
+    };
+  }
+
+  async merge(
+    sourceItemId: string,
+    dto: MergeFindingCatalogItemDto,
+    principal: AuthPrincipal,
+    request: RequestWithContext,
+  ) {
+    return this.dataSource.transaction(async (manager) => {
+      const existing = await manager.query(`
+        SELECT canonical_item_id AS "canonicalItemId"
+        FROM finding_catalog_item_merges WHERE source_item_id=$1::uuid
+      `, [sourceItemId]) as Array<{ canonicalItemId: string }>;
+      if (existing[0]) {
+        throw new ConflictException({
+          code: 'FINDING_CATALOG_ALREADY_MERGED',
+          message: 'Este Hallazgo de catálogo ya fue fusionado',
+          canonicalItemId: existing[0].canonicalItemId,
+        });
+      }
+
+      const canonicalItemId = await this.resolveCanonicalId(manager, dto.canonicalItemId);
+      if (canonicalItemId === sourceItemId) {
+        throw new BadRequestException({
+          code: 'FINDING_CATALOG_MERGE_CYCLE',
+          message: 'La fusión generaría un ciclo en el catálogo',
+        });
+      }
+
+      const ids = [sourceItemId, canonicalItemId].sort();
+      const rows = await manager.query(`
+        SELECT item.id,item.category_id AS "categoryId",category.code AS "categoryCode",
+          category.name AS "categoryName",item.code,item.source_number AS "sourceNumber",
+          item.title,item.legal_basis AS "legalBasis",item.glossary,item.import_note AS "importNote",
+          item.suggested_severity AS "suggestedSeverity",item.revision,item.is_active AS "isActive"
+        FROM finding_catalog_items item
+        JOIN finding_categories category ON category.id=item.category_id
+        WHERE item.id=ANY($1::uuid[])
+        ORDER BY item.id
+        FOR UPDATE OF item
+      `, [ids]) as CatalogItemRow[];
+      const source = rows.find((item) => item.id === sourceItemId);
+      const canonical = rows.find((item) => item.id === canonicalItemId);
+      if (!source || !canonical) throw new NotFoundException({
+        code: 'FINDING_CATALOG_ITEM_NOT_FOUND',
+        message: 'Hallazgo de catálogo no encontrado',
+      });
+      if (!source.isActive) throw new ConflictException({
+        code: 'FINDING_CATALOG_MERGE_SOURCE_INACTIVE',
+        message: 'El Hallazgo de origen ya está inactivo',
+      });
+      if (!canonical.isActive) throw new ConflictException({
+        code: 'FINDING_CATALOG_MERGE_CANONICAL_INACTIVE',
+        message: 'El Hallazgo canónico debe estar activo',
+      });
+
+      const sourceSnapshot = this.snapshot(source);
+      const canonicalSnapshot = this.snapshot(canonical);
+
+      // La aplicabilidad futura pasa al canónico; los Hallazgos emitidos nunca se reescriben.
+      await manager.query(`
+        INSERT INTO finding_catalog_item_inventory_families(catalog_item_id,inventory_family_id)
+        SELECT $2::uuid,inventory_family_id
+        FROM finding_catalog_item_inventory_families
+        WHERE catalog_item_id=$1::uuid
+        ON CONFLICT (catalog_item_id,inventory_family_id) DO NOTHING
+      `, [source.id, canonical.id]);
+      await manager.query(`
+        INSERT INTO finding_catalog_item_asset_types(catalog_item_id,asset_type_id,created_by)
+        SELECT $2::uuid,asset_type_id,$3::uuid
+        FROM finding_catalog_item_asset_types
+        WHERE catalog_item_id=$1::uuid
+        ON CONFLICT (catalog_item_id,asset_type_id) DO NOTHING
+      `, [source.id, canonical.id, principal.userId]);
+      await manager.query(`
+        INSERT INTO finding_catalog_asset_overrides(
+          asset_id,catalog_item_id,is_enabled,reason,created_by,updated_by
+        )
+        SELECT asset_id,$2::uuid,is_enabled,
+          'F3.1 merge catálogo: ' || COALESCE(reason,''),$3::uuid,$3::uuid
+        FROM finding_catalog_asset_overrides source_override
+        WHERE source_override.catalog_item_id=$1::uuid
+          AND NOT EXISTS (
+            SELECT 1 FROM finding_catalog_asset_overrides target_override
+            WHERE target_override.asset_id=source_override.asset_id
+              AND target_override.catalog_item_id=$2::uuid
+          )
+      `, [source.id, canonical.id, principal.userId]);
+
+      const [mergeRecord] = await manager.query(`
+        INSERT INTO finding_catalog_item_merges(
+          source_item_id,canonical_item_id,reason,merged_by,request_id,
+          source_snapshot,canonical_snapshot
+        ) VALUES ($1::uuid,$2::uuid,$3::text,$4::uuid,$5::varchar,$6::jsonb,$7::jsonb)
+        RETURNING id,source_item_id AS "sourceItemId",canonical_item_id AS "canonicalItemId",
+          reason,merged_at AS "mergedAt",merged_by AS "mergedBy",request_id AS "requestId"
+      `, [
+        source.id,
+        canonical.id,
+        dto.reason,
+        principal.userId,
+        request.requestId,
+        sourceSnapshot,
+        canonicalSnapshot,
+      ]) as Array<Record<string, unknown>>;
+
+      await manager.query(`
+        UPDATE finding_catalog_items
+        SET is_active=false,revision=revision+1,updated_at=CURRENT_TIMESTAMP
+        WHERE id=$1::uuid
+      `, [source.id]);
+      const updatedSource = await this.load(manager, source.id, false);
+      await manager.query(`
+        INSERT INTO finding_catalog_item_versions(
+          item_id,revision,snapshot,actor_user_id,actor_username
+        ) VALUES ($1::uuid,$2::integer,$3::jsonb,$4::uuid,$5::varchar)
+      `, [
+        updatedSource.id,
+        updatedSource.revision,
+        this.snapshot(updatedSource),
+        principal.userId,
+        principal.username,
+      ]);
+
+      await this.audit.record({
+        ...administrationAuditContext(principal, request),
+        action: AuditAction.FINDING_CATALOG_ITEM_UPDATED,
+        entityType: 'finding_catalog_item_merge',
+        entityId: String(mergeRecord.id),
+        beforeData: sourceSnapshot,
+        afterData: canonicalSnapshot,
+        metadata: {
+          operation: 'CHRONOLOGICAL_CATALOG_MERGE',
+          sourceItemId: source.id,
+          canonicalItemId: canonical.id,
+          reason: dto.reason,
+          historicalFindingsRewritten: false,
+          historicalProposalsRewritten: false,
+          futureApplicabilityMovedToCanonical: true,
+        },
+      }, manager);
+
+      return {
+        merge: mergeRecord,
+        source: updatedSource,
+        canonical,
+        historyPolicy: 'EMITTED_FINDINGS_PRESERVED',
+      };
+    });
+  }
+
+  private async resolveCanonicalId(manager: EntityManager, itemId: string): Promise<string> {
+    const rows = await manager.query(`
+      WITH RECURSIVE chain AS (
+        SELECT source_item_id,canonical_item_id,1 AS depth
+        FROM finding_catalog_item_merges WHERE source_item_id=$1::uuid
+        UNION ALL
+        SELECT merge_record.source_item_id,merge_record.canonical_item_id,chain.depth+1
+        FROM finding_catalog_item_merges merge_record
+        JOIN chain ON merge_record.source_item_id=chain.canonical_item_id
+        WHERE chain.depth<32
+      )
+      SELECT canonical_item_id AS id FROM chain ORDER BY depth DESC LIMIT 1
+    `, [itemId]) as Array<{ id: string }>;
+    return rows[0]?.id ?? itemId;
+  }
+
+  private async load(manager: EntityManager, itemId: string, lock: boolean): Promise<CatalogItemRow> {
+    const lockSql = lock ? 'FOR UPDATE OF item' : '';
+    const rows = await manager.query(`
+      SELECT item.id,item.category_id AS "categoryId",category.code AS "categoryCode",
+        category.name AS "categoryName",item.code,item.source_number AS "sourceNumber",
+        item.title,item.legal_basis AS "legalBasis",item.glossary,item.import_note AS "importNote",
+        item.suggested_severity AS "suggestedSeverity",item.revision,item.is_active AS "isActive"
+      FROM finding_catalog_items item
+      JOIN finding_categories category ON category.id=item.category_id
+      WHERE item.id=$1::uuid ${lockSql}
+    `, [itemId]) as CatalogItemRow[];
+    if (!rows[0]) throw new NotFoundException({
+      code: 'FINDING_CATALOG_ITEM_NOT_FOUND',
+      message: 'Hallazgo de catálogo no encontrado',
+    });
+    return rows[0];
+  }
+
+  private snapshot(item: CatalogItemRow): Record<string, unknown> {
+    return {
+      id: item.id,
+      categoryId: item.categoryId,
+      categoryCode: item.categoryCode,
+      categoryName: item.categoryName,
+      code: item.code,
+      sourceNumber: item.sourceNumber,
+      title: item.title,
+      legalBasis: item.legalBasis,
+      glossary: item.glossary,
+      importNote: item.importNote,
+      suggestedSeverity: item.suggestedSeverity,
+      revision: item.revision,
+      isActive: item.isActive,
+    };
+  }
+}