diff --git a/packages/scanner-core/src/result-aggregator.test.ts b/packages/scanner-core/src/result-aggregator.test.ts
new file mode 100644
index 0000000..ca2c906
--- /dev/null
+++ b/packages/scanner-core/src/result-aggregator.test.ts
@@ -0,0 +1,268 @@
+import type { FindingResult } from '@veridion/scanner-types';
+import { FindingSeverity } from '@veridion/shared';
+import { beforeEach, describe, expect, it } from 'vitest';
+
+import { ResultAggregator } from './result-aggregator';
+
+function createMockFinding(overrides: Partial<FindingResult> & { category?: string } = {}): FindingResult {
+  return {
+    pluginId: 'reentrancy',
+    title: 'Potential Vulnerability',
+    description: 'A mock vulnerability description',
+    severity: FindingSeverity.MEDIUM,
+    filePath: 'contracts/Token.sol',
+    lineStart: 10,
+    lineEnd: 15,
+    codeSnippet: 'msg.sender.call{value: amount}("");',
+    recommendation: 'Fix the vulnerability',
+    confidence: 0.8,
+    references: ['https://swcregistry.io/docs/SWC-107'],
+    ...overrides,
+  };
+}
+
+describe('ResultAggregator', () => {
+  let aggregator: ResultAggregator;
+
+  beforeEach(() => {
+    aggregator = new ResultAggregator();
+  });
+
+  describe('deduplicateFindings', () => {
+    it('should return an empty array when given no findings', () => {
+      expect(aggregator.deduplicateFindings([])).toEqual([]);
+    });
+
+    it('should return the single finding when only one is provided', () => {
+      const finding = createMockFinding();
+      expect(aggregator.deduplicateFindings([finding])).toEqual([finding]);
+    });
+
+    it('should deduplicate findings at the same file, line range, and category with same severity', () => {
+      const finding1 = createMockFinding({
+        pluginId: 'plugin-a',
+        confidence: 0.8,
+        description: 'First report',
+      });
+      const finding2 = createMockFinding({
+        pluginId: 'plugin-b',
+        confidence: 0.8,
+        description: 'Second report',
+      });
+
+      const result = aggregator.deduplicateFindings([
+        { ...finding1, category: 'REENTRANCY' },
+        { ...finding2, category: 'REENTRANCY' },
+      ]);
+
+      expect(result).toHaveLength(1);
+      expect(result[0]?.description).toBe('First report');
+    });
+
+    it('should keep higher confidence finding when severities are identical', () => {
+      const lowerConfidence = createMockFinding({
+        pluginId: 'plugin-a',
+        confidence: 0.6,
+        description: 'Lower confidence',
+      });
+      const higherConfidence = createMockFinding({
+        pluginId: 'plugin-b',
+        confidence: 0.95,
+        description: 'Higher confidence',
+      });
+
+      const result = aggregator.deduplicateFindings([
+        { ...lowerConfidence, category: 'REENTRANCY' },
+        { ...higherConfidence, category: 'REENTRANCY' },
+      ]);
+
+      expect(result).toHaveLength(1);
+      expect(result[0]?.confidence).toBe(0.95);
+      expect(result[0]?.description).toBe('Higher confidence');
+    });
+
+    it('should keep higher-severity finding when duplicates exist with different severities', () => {
+      const lowFinding = createMockFinding({
+        pluginId: 'plugin-low',
+        severity: FindingSeverity.LOW,
+        description: 'Low severity detection',
+      });
+      const criticalFinding = createMockFinding({
+        pluginId: 'plugin-crit',
+        severity: FindingSeverity.CRITICAL,
+        description: 'Critical severity detection',
+      });
+
+      const result1 = aggregator.deduplicateFindings([
+        { ...lowFinding, category: 'REENTRANCY' },
+        { ...criticalFinding, category: 'REENTRANCY' },
+      ]);
+
+      expect(result1).toHaveLength(1);
+      expect(result1[0]?.severity).toBe(FindingSeverity.CRITICAL);
+      expect(result1[0]?.description).toBe('Critical severity detection');
+
+      const result2 = aggregator.deduplicateFindings([
+        { ...criticalFinding, category: 'REENTRANCY' },
+        { ...lowFinding, category: 'REENTRANCY' },
+      ]);
+
+      expect(result2).toHaveLength(1);
+      expect(result2[0]?.severity).toBe(FindingSeverity.CRITICAL);
+    });
+
+    it('should correctly prioritize across all severity levels', () => {
+      const severities = [
+        FindingSeverity.INFORMATIONAL,
+        FindingSeverity.GAS,
+        FindingSeverity.LOW,
+        FindingSeverity.MEDIUM,
+        FindingSeverity.HIGH,
+        FindingSeverity.CRITICAL,
+      ];
+
+      for (let i = 0; i < severities.length - 1; i++) {
+        const lower = severities[i];
+        const higher = severities[i + 1];
+        if (!lower || !higher) continue;
+
+        const fLower = createMockFinding({ severity: lower });
+        const fHigher = createMockFinding({ severity: higher });
+
+        const result = aggregator.deduplicateFindings([
+          { ...fLower, category: 'CUSTOM' },
+          { ...fHigher, category: 'CUSTOM' },
+        ]);
+
+        expect(result).toHaveLength(1);
+        expect(result[0]?.severity).toBe(higher);
+      }
+    });
+
+    it('should not deduplicate findings with different file paths', () => {
+      const findingA = createMockFinding({ filePath: 'contracts/A.sol' });
+      const findingB = createMockFinding({ filePath: 'contracts/B.sol' });
+
+      const result = aggregator.deduplicateFindings([findingA, findingB]);
+      expect(result).toHaveLength(2);
+    });
+
+    it('should not deduplicate findings with different line ranges', () => {
+      const findingA = createMockFinding({ lineStart: 10, lineEnd: 15 });
+      const findingB = createMockFinding({ lineStart: 20, lineEnd: 25 });
+
+      const result = aggregator.deduplicateFindings([findingA, findingB]);
+      expect(result).toHaveLength(2);
+    });
+
+    it('should not deduplicate findings with different categories at the same location', () => {
+      const reentrancy = createMockFinding({
+        pluginId: 'reentrancy',
+      });
+      const accessControl = createMockFinding({
+        pluginId: 'access-control',
+      });
+
+      const result = aggregator.deduplicateFindings([
+        { ...reentrancy, category: 'REENTRANCY' },
+        { ...accessControl, category: 'ACCESS_CONTROL' },
+      ]);
+
+      expect(result).toHaveLength(2);
+    });
+
+    it('should fallback to pluginId as category when category is not explicitly provided', () => {
+      const finding1 = createMockFinding({ pluginId: 'detector-1' });
+      const finding2 = createMockFinding({ pluginId: 'detector-2' });
+
+      const result = aggregator.deduplicateFindings([finding1, finding2]);
+      expect(result).toHaveLength(2);
+    });
+  });
+
+  describe('summarize', () => {
+    it('should reflect deduplicated results in summary counts', () => {
+      const duplicateLow = createMockFinding({
+        filePath: 'contracts/Vault.sol',
+        lineStart: 50,
+        lineEnd: 55,
+        severity: FindingSeverity.LOW,
+      });
+      const duplicateHigh = createMockFinding({
+        filePath: 'contracts/Vault.sol',
+        lineStart: 50,
+        lineEnd: 55,
+        severity: FindingSeverity.HIGH,
+      });
+      const uniqueGas = createMockFinding({
+        filePath: 'contracts/Vault.sol',
+        lineStart: 80,
+        lineEnd: 82,
+        severity: FindingSeverity.GAS,
+      });
+
+      const findings = [
+        { ...duplicateLow, category: 'REENTRANCY' },
+        { ...duplicateHigh, category: 'REENTRANCY' },
+        { ...uniqueGas, category: 'GAS' },
+      ];
+
+      const summary = aggregator.summarize(findings);
+
+      expect(summary.total).toBe(2);
+      expect(summary.high).toBe(1);
+      expect(summary.low).toBe(0);
+      expect(summary.gas).toBe(1);
+      expect(summary.critical).toBe(0);
+      expect(summary.medium).toBe(0);
+      expect(summary.informational).toBe(0);
+    });
+
+    it('should correctly summarize empty findings', () => {
+      const summary = aggregator.summarize([]);
+      expect(summary.total).toBe(0);
+      expect(summary.critical).toBe(0);
+      expect(summary.high).toBe(0);
+      expect(summary.medium).toBe(0);
+      expect(summary.low).toBe(0);
+      expect(summary.gas).toBe(0);
+      expect(summary.informational).toBe(0);
+    });
+  });
+
+  describe('calculateScore', () => {
+    it('should return 100 for empty findings', () => {
+      expect(aggregator.calculateScore([])).toBe(100);
+    });
+
+    it('should calculate score based on findings and confidence', () => {
+      const findings = [
+        createMockFinding({ severity: FindingSeverity.CRITICAL, confidence: 1.0 }),
+      ];
+      const score = aggregator.calculateScore(findings);
+      expect(score).toBe(0);
+    });
+  });
+
+  describe('groupByPlugin and groupBySeverity', () => {
+    it('should group findings by plugin', () => {
+      const f1 = createMockFinding({ pluginId: 'plugin-1' });
+      const f2 = createMockFinding({ pluginId: 'plugin-2' });
+      const f3 = createMockFinding({ pluginId: 'plugin-1' });
+
+      const grouped = aggregator.groupByPlugin([f1, f2, f3]);
+      expect(grouped.get('plugin-1')).toHaveLength(2);
+      expect(grouped.get('plugin-2')).toHaveLength(1);
+    });
+
+    it('should group findings by severity', () => {
+      const f1 = createMockFinding({ severity: FindingSeverity.CRITICAL });
+      const f2 = createMockFinding({ severity: FindingSeverity.LOW });
+      const f3 = createMockFinding({ severity: FindingSeverity.CRITICAL });
+
+      const grouped = aggregator.groupBySeverity([f1, f2, f3]);
+      expect(grouped.get(FindingSeverity.CRITICAL)).toHaveLength(2);
+      expect(grouped.get(FindingSeverity.LOW)).toHaveLength(1);
+    });
+  });
+});
diff --git a/packages/scanner-core/src/result-aggregator.ts b/packages/scanner-core/src/result-aggregator.ts
index 195b3d9..bf58916 100644
--- a/packages/scanner-core/src/result-aggregator.ts
+++ b/packages/scanner-core/src/result-aggregator.ts
@@ -11,16 +11,53 @@ export interface FindingSummary {
   total: number;
 }
 
+const SEVERITY_RANK: Record<FindingSeverity, number> = {
+  [FindingSeverity.CRITICAL]: 5,
+  [FindingSeverity.HIGH]: 4,
+  [FindingSeverity.MEDIUM]: 3,
+  [FindingSeverity.LOW]: 2,
+  [FindingSeverity.GAS]: 1,
+  [FindingSeverity.INFORMATIONAL]: 0,
+};
+
 export class ResultAggregator {
+  deduplicateFindings(findings: FindingResult[]): FindingResult[] {
+    const map = new Map<string, FindingResult>();
+
+    for (const finding of findings) {
+      const category =
+        (finding as FindingResult & { category?: string }).category ?? finding.pluginId;
+      const key = `${finding.filePath}:${finding.lineStart}:${finding.lineEnd}:${category}`;
+
+      const existing = map.get(key);
+      if (!existing) {
+        map.set(key, finding);
+        continue;
+      }
+
+      const existingRank = SEVERITY_RANK[existing.severity] ?? -1;
+      const newRank = SEVERITY_RANK[finding.severity] ?? -1;
+
+      if (newRank > existingRank) {
+        map.set(key, finding);
+      } else if (newRank === existingRank && finding.confidence > existing.confidence) {
+        map.set(key, finding);
+      }
+    }
+
+    return Array.from(map.values());
+  }
+
   summarize(findings: FindingResult[]): FindingSummary {
+    const deduped = this.deduplicateFindings(findings);
     return {
-      critical: this.countBySeverity(findings, FindingSeverity.CRITICAL),
-      high: this.countBySeverity(findings, FindingSeverity.HIGH),
-      medium: this.countBySeverity(findings, FindingSeverity.MEDIUM),
-      low: this.countBySeverity(findings, FindingSeverity.LOW),
-      gas: this.countBySeverity(findings, FindingSeverity.GAS),
-      informational: this.countBySeverity(findings, FindingSeverity.INFORMATIONAL),
-      total: findings.length,
+      critical: this.countBySeverity(deduped, FindingSeverity.CRITICAL),
+      high: this.countBySeverity(deduped, FindingSeverity.HIGH),
+      medium: this.countBySeverity(deduped, FindingSeverity.MEDIUM),
+      low: this.countBySeverity(deduped, FindingSeverity.LOW),
+      gas: this.countBySeverity(deduped, FindingSeverity.GAS),
+      informational: this.countBySeverity(deduped, FindingSeverity.INFORMATIONAL),
+      total: deduped.length,
     };
   }
 
diff --git a/packages/scanner-types/src/index.ts b/packages/scanner-types/src/index.ts
index 5c15f23..8eeb72c 100644
--- a/packages/scanner-types/src/index.ts
+++ b/packages/scanner-types/src/index.ts
@@ -51,6 +51,7 @@ export interface FindingResult {
   recommendation: string;
   confidence: number;
   references: string[];
+  category?: PluginCategory | string;
 }
 
 export interface IRulePlugin {
diff --git a/packages/shared/src/types/plugin.ts b/packages/shared/src/types/plugin.ts
index 355ed9e..d207860 100644
--- a/packages/shared/src/types/plugin.ts
+++ b/packages/shared/src/types/plugin.ts
@@ -57,4 +57,5 @@ export interface FindingResult {
   recommendation: string;
   confidence: number;
   references: string[];
+  category?: PluginCategory | string;
 }