diff --git a/yarn-project/aztec.js/src/api/abi.ts b/yarn-project/aztec.js/src/api/abi.ts
index 56ff6448708a..847b1708f7eb 100644
--- a/yarn-project/aztec.js/src/api/abi.ts
+++ b/yarn-project/aztec.js/src/api/abi.ts
@@ -17,6 +17,7 @@ export {
   isWrappedFieldStruct,
   isFunctionSelectorStruct,
   loadContractArtifact,
+  loadContractArtifactWithValidation,
   loadContractArtifactForPublic,
   getAllFunctionAbis,
   contractArtifactToBuffer,
diff --git a/yarn-project/cli/src/utils/aztec.ts b/yarn-project/cli/src/utils/aztec.ts
index 89502f5c47a4..4f157d08ae04 100644
--- a/yarn-project/cli/src/utils/aztec.ts
+++ b/yarn-project/cli/src/utils/aztec.ts
@@ -3,7 +3,7 @@ import {
   type FunctionAbi,
   FunctionType,
   getAllFunctionAbis,
-  loadContractArtifact,
+  loadContractArtifactWithValidation,
 } from '@aztec/aztec.js/abi';
 import { EthAddress } from '@aztec/aztec.js/addresses';
 import type { L1ContractsConfig } from '@aztec/ethereum/config';
@@ -132,7 +132,7 @@ export async function getContractArtifact(fileDir: string, log: LogFn) {
   }
 
   try {
-    return loadContractArtifact(JSON.parse(contents));
+    return loadContractArtifactWithValidation(JSON.parse(contents));
   } catch (err) {
     log('Invalid file used. Please try again.');
     throw err;
diff --git a/yarn-project/ethereum/src/utils.test.ts b/yarn-project/ethereum/src/utils.test.ts
index d31c5a6a6c0d..723c740585a2 100644
--- a/yarn-project/ethereum/src/utils.test.ts
+++ b/yarn-project/ethereum/src/utils.test.ts
@@ -1,6 +1,6 @@
 import type { Abi } from 'viem';
 
-import { mergeAbis } from './utils.js';
+import { FormattedViemError, formatViemError, mergeAbis } from './utils.js';
 
 describe('mergeAbis', () => {
   it('dedupes identical function items', () => {
@@ -59,3 +59,19 @@ describe('mergeAbis', () => {
     expect(merged).toHaveLength(2);
   });
 });
+
+describe('formatViemError', () => {
+  it('formats an error whose cause carries non-cloneable function-valued context', () => {
+    // viem RPC errors routinely attach plain-object context holding functions (e.g. transport
+    // request methods). structuredClone throws DataCloneError on these, so formatViemError must
+    // not let the clone failure mask the underlying error.
+    const error = new Error('rpc request failed');
+    (error as any).cause = { code: -32000, request: { send: () => undefined } };
+
+    const formatted = formatViemError(error);
+
+    expect(formatted).toBeInstanceOf(FormattedViemError);
+    expect(formatted.message).toContain('rpc request failed');
+    expect(formatted.cause).toBe(error);
+  });
+});
diff --git a/yarn-project/ethereum/src/utils.ts b/yarn-project/ethereum/src/utils.ts
index 543df2182bc9..5a05d806ab12 100644
--- a/yarn-project/ethereum/src/utils.ts
+++ b/yarn-project/ethereum/src/utils.ts
@@ -235,18 +235,18 @@ export function formatViemError(error: any, abi: Abi = ErrorsAbi): FormattedViem
     // If decoding fails, we fall back to the original formatting
   }
 
-  // Strip ABI from the error object before formatting
+  // Strip ABI from the error object before formatting. We clone first to avoid mutating the
+  // caller's error, but structuredClone throws DataCloneError on values it cannot clone (e.g.
+  // viem RPC errors carrying function-valued request context). If cloning fails, fall back to
+  // formatting the original error untouched rather than letting the clone failure mask it.
   if (error && typeof error === 'object') {
-    // Create a clone to avoid modifying the original
-    const errorClone = structuredClone(error);
-
-    // Helper function to recursively remove ABI properties
-
-    // Strip ABIs from the clone
-    stripAbis(errorClone);
-
-    // Use the cleaned clone for further processing
-    error = errorClone;
+    try {
+      const errorClone = structuredClone(error);
+      stripAbis(errorClone);
+      error = errorClone;
+    } catch {
+      // Leave `error` as the original; we skip stripAbis to avoid mutating the caller's object.
+    }
   }
 
   // If it's a regular Error instance, return it with its message
diff --git a/yarn-project/stdlib/src/abi/contract_artifact.test.ts b/yarn-project/stdlib/src/abi/contract_artifact.test.ts
index 5413028e4a7a..4b41394fe44a 100644
--- a/yarn-project/stdlib/src/abi/contract_artifact.test.ts
+++ b/yarn-project/stdlib/src/abi/contract_artifact.test.ts
@@ -1,5 +1,9 @@
 import { getBenchmarkContractArtifact } from '../tests/fixtures.js';
-import { contractArtifactFromBuffer, contractArtifactToBuffer } from './contract_artifact.js';
+import {
+  contractArtifactFromBuffer,
+  contractArtifactToBuffer,
+  loadContractArtifactWithValidation,
+} from './contract_artifact.js';
 
 describe('contract_artifact', () => {
   it('serializes and deserializes an instance', () => {
@@ -8,4 +12,23 @@ describe('contract_artifact', () => {
     const deserialized = contractArtifactFromBuffer(serialized);
     expect(deserialized).toEqual(artifact);
   });
+
+  describe('loadContractArtifactWithValidation', () => {
+    // The wire form of an already-processed artifact (hex/base64 strings) is what reaches the
+    // loader from a JSON file, e.g. via the CLI deploy command.
+    const wireForm = () => JSON.parse(contractArtifactToBuffer(getBenchmarkContractArtifact()).toString('utf-8'));
+
+    it('accepts a valid already-processed artifact', () => {
+      const loaded = loadContractArtifactWithValidation(wireForm());
+      expect(loaded.name).toEqual(getBenchmarkContractArtifact().name);
+    });
+
+    it('rejects an artifact that passes the shallow shape check but violates the schema', () => {
+      const input = wireForm();
+      // functionType stays a string, so the shallow isContractArtifact() heuristic still passes,
+      // but it is not a valid FunctionType enum value, so full schema validation must reject it.
+      input.functions[0].functionType = 'not-a-real-type';
+      expect(() => loadContractArtifactWithValidation(input)).toThrow();
+    });
+  });
 });
diff --git a/yarn-project/stdlib/src/abi/contract_artifact.ts b/yarn-project/stdlib/src/abi/contract_artifact.ts
index b3cfc0e919d2..d04f3fea090f 100644
--- a/yarn-project/stdlib/src/abi/contract_artifact.ts
+++ b/yarn-project/stdlib/src/abi/contract_artifact.ts
@@ -61,6 +61,25 @@ export function loadContractArtifact(input: NoirCompiledContract): ContractArtif
   return generateContractArtifact(input);
 }
 
+/**
+ * Like {@link loadContractArtifact}, but fully validates an already-processed artifact against the
+ * contract artifact schema before returning it. Use when loading an artifact from untrusted or
+ * external JSON (e.g. a file path passed to the CLI), so a malformed artifact is rejected up-front
+ * with a clear schema error instead of surfacing as an opaque failure later during deployment.
+ *
+ * `loadContractArtifact` only runs the shallow `isContractArtifact` shape check on already-processed
+ * artifacts; raw nargo output is validated via `generateContractArtifact` regardless. The returned
+ * object is identical to `loadContractArtifact`'s; the schema parse is used purely for validation.
+ * @param input - Input object as generated by nargo compile, or an already-processed artifact.
+ * @returns A valid contract artifact instance.
+ */
+export function loadContractArtifactWithValidation(input: NoirCompiledContract): ContractArtifact {
+  if (isContractArtifact(input)) {
+    ContractArtifactSchema.parse(input);
+  }
+  return loadContractArtifact(input);
+}
+
 /**
  * Gets nargo build output and returns a valid contract artifact instance.
  * Differs from loadContractArtifact() by retaining all bytecode.