diff --git a/CHANGELOG.md b/CHANGELOG.md
index 08703a26..2e4a2fe7 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -16,6 +16,11 @@
 
 - Deleted stray artifacts from the working tree: `autotask-node-2.0.0.tgz`, `npm-debug-403.log`, and the empty `logs/` directory.
 
+### Fixed
+
+- **Cleared the 17 real ESLint errors (`preserve-caught-error`, `no-useless-assignment`) that a bumped `eslint`/`@typescript-eslint/eslint-plugin` devDependency newly surfaces on pre-existing code, blocking dependabot dev-dependency PRs (#233 and any future bump hitting the same two rules).** 8 `preserve-caught-error` sites now attach `{ cause: <caughtError> }` to the re-thrown `Error`. 8 `no-useless-assignment` sites were genuine dead stores (a `let` initializer or intermediate assignment never read before being overwritten or falling out of scope) and had the dead assignment removed. One site (`test/base.test.ts`, a `WeakRef` GC test) is an intentional false positive — nulling the variable has a real side effect (dropping the last strong reference so `global.gc()` can collect it) even though the linter can't see a subsequent read — kept via a scoped `eslint-disable-next-line` with an inline explanation rather than removed.
+- Added `ES2022.Error` to `tsconfig.json`'s `lib` array (alongside the existing `ES2021`) — the two-argument `Error(message, { cause })` constructor form needs it for type-checking; `target` is unchanged (still `ES2020`), so output syntax is unaffected.
+
 ### Security
 
 - **Closed GHSA-r292-9mhp-454m (node-tar uncontrolled recursion, high, stack-overflow DoS via crafted long-path tar).** Bundled `tar` (pulled in transitively via the `npm` CLI devDependency, itself pulled in via `@semantic-release/npm`) was at 7.5.19/7.5.20, just short of the 7.5.21 patch. A plain `npm audit fix` (no `--force`) re-resolved `npm` to 11.19.1 (bundled tar 7.5.22) within the existing declared range — lockfile-only change, no `package.json`/direct-dependency edits, no semver-major bump. `npm audit`'s own suggested remediation path (`semantic-release@24.2.9`, flagged `isSemVerMajor`) was a red herring — the currently-resolved `semantic-release` (25.0.3, newer than that suggestion) was never at risk and is unchanged by this fix.
diff --git a/examples/shared/auth/autotask-auth.ts b/examples/shared/auth/autotask-auth.ts
index 024716d5..9ea5d51d 100644
--- a/examples/shared/auth/autotask-auth.ts
+++ b/examples/shared/auth/autotask-auth.ts
@@ -48,7 +48,7 @@ export class AutotaskAuthManager {
       logger.info('Autotask connection initialized successfully');
     } catch (error) {
       logger.error('Failed to initialize Autotask connection:', error);
-      throw new Error(`Autotask authentication failed: ${error instanceof Error ? error.message : 'Unknown error'}`);
+      throw new Error(`Autotask authentication failed: ${error instanceof Error ? error.message : 'Unknown error'}`, { cause: error });
     }
   }
 
diff --git a/src/caching/TTLManager.ts b/src/caching/TTLManager.ts
index bb0ba4d8..14031fb5 100644
--- a/src/caching/TTLManager.ts
+++ b/src/caching/TTLManager.ts
@@ -324,7 +324,7 @@ export class TTLManager {
                            hour >= this.businessHours.startHour &&
                            hour < this.businessHours.endHour;
 
-    let ttlMultiplier = 1;
+    let ttlMultiplier: number;
     let confidence = 0.7;
     let reason: string;
 
diff --git a/src/caching/stores/FileCacheStore.ts b/src/caching/stores/FileCacheStore.ts
index acaac9c9..a2388f8f 100644
--- a/src/caching/stores/FileCacheStore.ts
+++ b/src/caching/stores/FileCacheStore.ts
@@ -852,7 +852,7 @@ export class FileCacheStore implements ICacheStore {
    */
   private async performCleanup(): Promise<number> {
     const now = Date.now();
-    let deletedCount = 0;
+    let deletedCount: number;
     const expiredKeys: string[] = [];
 
     // Find expired keys
diff --git a/src/migration/cli/MigrationCLI.ts b/src/migration/cli/MigrationCLI.ts
index 552a7164..ae5c9a65 100644
--- a/src/migration/cli/MigrationCLI.ts
+++ b/src/migration/cli/MigrationCLI.ts
@@ -387,7 +387,7 @@ async function loadConfig(): Promise<MigrationConfig> {
     const configContent = await fs.readFile(configPath, 'utf8');
     return JSON.parse(configContent);
   } catch (error) {
-    throw new Error(`Failed to load configuration from ${configPath}. Run 'autotask-migrate init' first.`);
+    throw new Error(`Failed to load configuration from ${configPath}. Run 'autotask-migrate init' first.`, { cause: error });
   }
 }
 
diff --git a/src/performance/monitoring/ConnectionPoolMonitor.ts b/src/performance/monitoring/ConnectionPoolMonitor.ts
index 55a4448c..797cee03 100644
--- a/src/performance/monitoring/ConnectionPoolMonitor.ts
+++ b/src/performance/monitoring/ConnectionPoolMonitor.ts
@@ -302,8 +302,8 @@ export class ConnectionPoolMonitor extends EventEmitter {
     // In a real implementation, this would query actual HTTP agents
     // For now, we'll simulate metrics based on recorded events
     
-    let totalConnections = 0;
-    let activeConnections = 0;
+    let totalConnections: number;
+    let activeConnections: number;
     let connectionsCreated = 0;
     let connectionsDestroyed = 0;
     let totalAcquisitionTime = 0;
diff --git a/src/relationships/loading/SmartLoadingEngine.ts b/src/relationships/loading/SmartLoadingEngine.ts
index de74e9e4..1dba4828 100644
--- a/src/relationships/loading/SmartLoadingEngine.ts
+++ b/src/relationships/loading/SmartLoadingEngine.ts
@@ -539,7 +539,7 @@ export class SmartLoadingEngine {
     }
 
     // Execute query based on relationship type
-    let relatedData: any[] = [];
+    let relatedData: any[];
 
     try {
       switch (relationship.relationshipType) {
@@ -562,7 +562,7 @@ export class SmartLoadingEngine {
       }
 
     } catch (error) {
-      throw new Error(`Failed to load ${relationshipName}: ${(error as Error).message}`);
+      throw new Error(`Failed to load ${relationshipName}: ${(error as Error).message}`, { cause: error });
     }
 
     return relatedData;
diff --git a/src/tools/client-generator.ts b/src/tools/client-generator.ts
index 8c2c2a20..9753c841 100644
--- a/src/tools/client-generator.ts
+++ b/src/tools/client-generator.ts
@@ -64,7 +64,7 @@ class ClientGenerator {
       const data = fs.readFileSync(this.dataFile, 'utf8');
       return JSON.parse(data) as EntitiesData;
     } catch (error) {
-      throw new Error(`Failed to load entity data: ${error}`);
+      throw new Error(`Failed to load entity data: ${error}`, { cause: error });
     }
   }
 
diff --git a/src/tools/entity-generator.ts b/src/tools/entity-generator.ts
index b2422913..76961238 100644
--- a/src/tools/entity-generator.ts
+++ b/src/tools/entity-generator.ts
@@ -55,7 +55,7 @@ class EntityGenerator {
       const data = fs.readFileSync(this.dataFile, 'utf8');
       return JSON.parse(data) as EntitiesData;
     } catch (error) {
-      throw new Error(`Failed to load entity data: ${error}`);
+      throw new Error(`Failed to load entity data: ${error}`, { cause: error });
     }
   }
 
diff --git a/src/validation/index.ts b/src/validation/index.ts
index 8f0190b2..ffecf14b 100644
--- a/src/validation/index.ts
+++ b/src/validation/index.ts
@@ -466,7 +466,8 @@ export class ValidationDecorators {
             }
           } catch (error) {
             throw new Error(
-              `Validation error: ${error instanceof Error ? error.message : String(error)}`
+              `Validation error: ${error instanceof Error ? error.message : String(error)}`,
+              { cause: error }
             );
           }
         }
diff --git a/src/validation/security/SecurityValidator.ts b/src/validation/security/SecurityValidator.ts
index b1f073c7..c10f184e 100644
--- a/src/validation/security/SecurityValidator.ts
+++ b/src/validation/security/SecurityValidator.ts
@@ -729,7 +729,7 @@ export class SecurityValidator {
       return 'ENC:' + CryptoJS.AES.encrypt(value, this.encryptionKey).toString();
     } catch (error) {
       this.logger.error('Encryption error:', error);
-      throw new Error('Failed to encrypt value');
+      throw new Error('Failed to encrypt value', { cause: error });
     }
   }
 
diff --git a/src/webhooks/reliability/EventStore.ts b/src/webhooks/reliability/EventStore.ts
index 6fb05932..dfa16661 100644
--- a/src/webhooks/reliability/EventStore.ts
+++ b/src/webhooks/reliability/EventStore.ts
@@ -321,7 +321,7 @@ export class EventStore extends EventEmitter implements IEventStore {
 
   public async getByFilter(filter: EventStoreFilter): Promise<WebhookEvent[]> {
     const startTime = Date.now();
-    let eventIds: Set<string> = new Set();
+    let eventIds: Set<string>;
 
     try {
       // Use index for efficient filtering if available
@@ -402,7 +402,6 @@ export class EventStore extends EventEmitter implements IEventStore {
       candidateIds = firstFilter
         ? dateIds
         : this.intersect(candidateIds, dateIds);
-      firstFilter = false;
     }
 
     return candidateIds;
diff --git a/test/base.test.ts b/test/base.test.ts
index 982863a3..3f1ebfc4 100644
--- a/test/base.test.ts
+++ b/test/base.test.ts
@@ -759,7 +759,10 @@ describe('BaseEntity - Comprehensive Tests', () => {
 
       await testEntity.testExecuteRequest(requestFn, '/test', 'GET');
 
-      requestFn = null; // Remove our reference
+      // Intentional dead-looking store: drops the last strong reference so
+      // `global.gc()` below can actually collect it for the WeakRef check.
+      // eslint-disable-next-line no-useless-assignment
+      requestFn = null;
       
       // Force garbage collection if available (for testing environments)
       if (global.gc) {
diff --git a/test/integration/framework/TestEnvironment.ts b/test/integration/framework/TestEnvironment.ts
index d977b2e3..8aeb7c06 100644
--- a/test/integration/framework/TestEnvironment.ts
+++ b/test/integration/framework/TestEnvironment.ts
@@ -135,7 +135,7 @@ export class TestEnvironment {
       // Test basic connectivity with a simple list operation
       await this.client.version.list({ pageSize: 1 });
     } catch (error) {
-      throw new Error(`Connection validation failed: ${error}`);
+      throw new Error(`Connection validation failed: ${error}`, { cause: error });
     }
   }
 
diff --git a/test/integration/setup-enhanced.ts b/test/integration/setup-enhanced.ts
index 3edb157f..3ca237fb 100644
--- a/test/integration/setup-enhanced.ts
+++ b/test/integration/setup-enhanced.ts
@@ -58,7 +58,7 @@ export default async function globalSetup(): Promise<void> {
       console.log('✅ API connection successful');
     } catch (error) {
       console.error('❌ API connection failed:', error);
-      throw new Error('API connection validation failed');
+      throw new Error('API connection validation failed', { cause: error });
     }
     
     // Store global instances
diff --git a/tsconfig.json b/tsconfig.json
index a37c2922..10bf4425 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -2,7 +2,8 @@
   "compilerOptions": {
     "target": "ES2020",
     "lib": [
-      "ES2021"
+      "ES2021",
+      "ES2022.Error"
     ],
     "module": "CommonJS",
     "moduleResolution": "Node",