diff --git a/Sources/OpenAI/Public/ResponseModels/VectorStoreFile/VectorStoreFileObject.swift b/Sources/OpenAI/Public/ResponseModels/VectorStoreFile/VectorStoreFileObject.swift
index db51b09b..f1021b57 100644
--- a/Sources/OpenAI/Public/ResponseModels/VectorStoreFile/VectorStoreFileObject.swift
+++ b/Sources/OpenAI/Public/ResponseModels/VectorStoreFile/VectorStoreFileObject.swift
@@ -23,4 +23,15 @@ public struct VectorStoreFileObject: Decodable {
   public let status: String
   /// The last error associated with this vector store file. Will be null if there are no errors.
   public let lastError: LastError?
+
+  enum CodingKeys: String, CodingKey {
+    case id
+    case object
+    case usageBytes = "usage_bytes"
+    case createdAt = "created_at"
+    case vectorStoreID = "vector_store_id"
+    case status
+    case lastError = "last_error"
+  }
+
 }
diff --git a/Tests/OpenAITests/VectorStoreFileObjectTests.swift b/Tests/OpenAITests/VectorStoreFileObjectTests.swift
new file mode 100644
index 00000000..b287a796
--- /dev/null
+++ b/Tests/OpenAITests/VectorStoreFileObjectTests.swift
@@ -0,0 +1,115 @@
+import XCTest
+@testable import SwiftOpenAI
+
+// MARK: - VectorStoreFileObjectTests
+
+final class VectorStoreFileObjectTests: XCTestCase {
+  func testDecodesSnakeCaseFieldsAndZeroUsage() throws {
+    let file = try JSONDecoder().decode(VectorStoreFileObject.self, from: fixture(usage: 0))
+    XCTAssertEqual(file.id, "file_fixture")
+    XCTAssertEqual(file.object, "vector_store.file")
+    XCTAssertEqual(file.usageBytes, 0)
+    XCTAssertEqual(file.createdAt, 1_711_027_402)
+    XCTAssertEqual(file.vectorStoreID, "vs_fixture")
+    XCTAssertEqual(file.status, "in_progress")
+    XCTAssertNil(file.lastError)
+  }
+
+  func testDecodesNonNullLastError() throws {
+    let file = try JSONDecoder().decode(VectorStoreFileObject.self, from: fixture(usage: 19, failed: true))
+    XCTAssertEqual(file.usageBytes, 19)
+    XCTAssertEqual(file.status, "failed")
+    XCTAssertEqual(file.lastError?.code, "server_error")
+    XCTAssertEqual(file.lastError?.message, "fixture error")
+  }
+
+  func testMissingLastErrorRemainsOptional() throws {
+    var json = try XCTUnwrap(JSONSerialization.jsonObject(with: fixture(usage: 0)) as? [String: Any])
+    json.removeValue(forKey: "last_error")
+    let file = try JSONDecoder().decode(VectorStoreFileObject.self, from: JSONSerialization.data(withJSONObject: json))
+    XCTAssertNil(file.lastError)
+  }
+
+  func testRequiredFieldsAndTypesRemainStrict() throws {
+    let original = try XCTUnwrap(JSONSerialization.jsonObject(with: fixture(usage: 0)) as? [String: Any])
+    for key in ["id", "object", "usage_bytes", "created_at", "vector_store_id", "status"] {
+      var missing = original
+      missing.removeValue(forKey: key)
+      XCTAssertThrowsError(
+        try JSONDecoder().decode(VectorStoreFileObject.self, from: JSONSerialization.data(withJSONObject: missing)),
+        key)
+      var null = original
+      null[key] = NSNull()
+      XCTAssertThrowsError(
+        try JSONDecoder().decode(VectorStoreFileObject.self, from: JSONSerialization.data(withJSONObject: null)),
+        key)
+    }
+    for key in ["usage_bytes", "created_at", "last_error"] {
+      var invalid = original
+      invalid[key] = "invalid"
+      XCTAssertThrowsError(
+        try JSONDecoder().decode(VectorStoreFileObject.self, from: JSONSerialization.data(withJSONObject: invalid)),
+        key)
+    }
+  }
+
+  func testDefaultServiceDecodesSingleAndListResponses() async throws {
+    for failed in [false, true] {
+      let client = try VectorStoreFixtureClient(payload: fixture(usage: failed ? 19 : 0, failed: failed))
+      let service = OpenAIServiceFactory.service(apiKey: "fixture-not-a-real-key", httpClient: client)
+      let created = try await service.createVectorStoreFile(
+        vectorStoreID: "vs_fixture", parameters: VectorStoreFileParameter(fileID: "file_fixture"))
+      let retrieved = try await service.retrieveVectorStoreFile(vectorStoreID: "vs_fixture", fileID: "file_fixture")
+      let listed = try await service.listVectorStoreFiles(
+        vectorStoreID: "vs_fixture", limit: nil, order: nil, after: nil, before: nil, filter: nil)
+      let batch = try await service.listVectorStoreFilesInABatch(
+        vectorStoreID: "vs_fixture", batchID: "batch_fixture", limit: nil, order: nil, after: nil, before: nil, filter: nil)
+      XCTAssertEqual(listed.data.count, 1)
+      XCTAssertEqual(batch.data.count, 1)
+      for file in [created, retrieved] + listed.data + batch.data {
+        XCTAssertEqual(file.usageBytes, failed ? 19 : 0)
+        XCTAssertEqual(file.createdAt, 1_711_027_402)
+        XCTAssertEqual(file.vectorStoreID, "vs_fixture")
+        XCTAssertEqual(file.status, failed ? "failed" : "in_progress")
+        XCTAssertEqual(file.lastError?.message, failed ? "fixture error" : nil)
+      }
+    }
+  }
+
+  private func fixture(usage: Int, failed: Bool = false) throws -> Data {
+    try JSONSerialization.data(withJSONObject: [
+      "id": "file_fixture",
+      "object": "vector_store.file",
+      "usage_bytes": usage,
+      "created_at": 1_711_027_402,
+      "vector_store_id": "vs_fixture",
+      "status": failed ? "failed" : "in_progress",
+      "last_error": failed ? ["code": "server_error", "message": "fixture error"] : NSNull(),
+    ] as [String: Any])
+  }
+}
+
+// MARK: - VectorStoreFixtureClient
+
+private final class VectorStoreFixtureClient: HTTPClient {
+  init(payload: Data) {
+    self.payload = payload
+  }
+
+  let payload: Data
+
+  func data(for request: HTTPRequest) async throws -> (Data, HTTPResponse) {
+    let body: Data
+    if request.method == .get, request.url.path.hasSuffix("/files") {
+      let file = try JSONSerialization.jsonObject(with: payload)
+      body = try JSONSerialization.data(withJSONObject: ["object": "list", "data": [file], "has_more": false])
+    } else {
+      body = payload
+    }
+    return (body, HTTPResponse(statusCode: 200, headers: [:]))
+  }
+
+  func bytes(for _: HTTPRequest) async throws -> (HTTPByteStream, HTTPResponse) {
+    throw URLError(.unsupportedURL)
+  }
+}