mindbox-cloud · Vailence · Apr 29, 2026 · Apr 28, 2026 · Apr 29, 2026 · Apr 29, 2026
diff --git a/Mindbox.xcodeproj/project.pbxproj b/Mindbox.xcodeproj/project.pbxproj
@@ -1437,39 +1437,9 @@
 /* End PBXFileReference section */
 
 /* Begin PBXFileSystemSynchronizedRootGroup section */
-		F385631E2DB6729000D91208 /* InappConfigurationDataFacade */ = {
-			isa = PBXFileSystemSynchronizedRootGroup;
-			exceptions = (
-			);
-			explicitFileTypes = {
-			};
-			explicitFolders = (
-			);
-			path = InappConfigurationDataFacade;
-			sourceTree = "<group>";
-		};
-		F397DE1C2CFF568800B72DA9 /* JSONs */ = {
-			isa = PBXFileSystemSynchronizedRootGroup;
-			exceptions = (
-			);
-			explicitFileTypes = {
-			};
-			explicitFolders = (
-			);
-			path = JSONs;
-			sourceTree = "<group>";
-		};
-		F3DEB38C2D47CBA200D0EFA4 /* InappSessionManagerTests */ = {
-			isa = PBXFileSystemSynchronizedRootGroup;
-			exceptions = (
-			);
-			explicitFileTypes = {
-			};
-			explicitFolders = (
-			);
-			path = InappSessionManagerTests;
-			sourceTree = "<group>";
-		};
+		F385631E2DB6729000D91208 /* InappConfigurationDataFacade */ = {isa = PBXFileSystemSynchronizedRootGroup; explicitFileTypes = {}; explicitFolders = (); path = InappConfigurationDataFacade; sourceTree = "<group>"; };
+		F397DE1C2CFF568800B72DA9 /* JSONs */ = {isa = PBXFileSystemSynchronizedRootGroup; explicitFileTypes = {}; explicitFolders = (); path = JSONs; sourceTree = "<group>"; };
+		F3DEB38C2D47CBA200D0EFA4 /* InappSessionManagerTests */ = {isa = PBXFileSystemSynchronizedRootGroup; explicitFileTypes = {}; explicitFolders = (); path = InappSessionManagerTests; sourceTree = "<group>"; };
 /* End PBXFileSystemSynchronizedRootGroup section */
 
 /* Begin PBXFrameworksBuildPhase section */
@@ -2280,7 +2250,6 @@
 				F3BA5E000130A000C0000006 /* OperationsURLRoutingTests.swift */,
 				F3CD202C2F600A800065392A /* HostNormalizerTests.swift */,
 			);
-			name = Network;
 			path = Network;
 			sourceTree = "<group>";
 		};
@@ -2289,7 +2258,6 @@
 			children = (
 				0475E8755F63483597539A50 /* TrackVisitManagerTests.swift */,
 			);
-			name = TrackVisitManager;
 			path = TrackVisitManager;
 			sourceTree = "<group>";
 		};
@@ -2440,7 +2408,6 @@
 				F3A8B9912A3A408C00E9C055 /* SDKVersionValidator.swift */,
 				F3A8B9992A3A471800E9C055 /* ABTestVariantsValidator.swift */,
 				F3A8B99D2A3A4FD600E9C055 /* ABTestValidator.swift */,
-				F3482F292A65DCFC002A41EC /* String+Extensions.swift */,
 				F34A45AF2B762A6100634C8B /* MindboxPushValidator.swift */,
 				F31A947F2BC7E61800E6C978 /* InappFrequencyValidator.swift */,
 			);
@@ -3016,7 +2983,6 @@
 			children = (
 				A1B2C3D4E5F6A7B8C9D0E1F3 /* MotionService.swift */,
 			);
-			name = Motion;
 			path = Motion;
 			sourceTree = "<group>";
 		};
@@ -3591,6 +3557,7 @@
 				BB65630F2BE3BA430090C473 /* UIApplication+Extensions.swift */,
 				F31DB4072F56A50E00DCEB85 /* NSError+Extensions.swift */,
 				326423031CA9C6BF0E62BEFD /* Date+Extensions.swift */,
+				F3482F292A65DCFC002A41EC /* String+Extensions.swift */,
 			);
 			path = Extensions;
 			sourceTree = "<group>";

diff --git a/Mindbox/Validators/String+Extensions.swift → Mindbox/Extensions/String+Extensions.swift b/Mindbox/Validators/String+Extensions.swift → Mindbox/Extensions/String+Extensions.swift
@@ -48,3 +48,24 @@ extension String {
         return hexValue.unicodeScalars.allSatisfy { hexCharacterSet.contains($0) }
     }
 }
+
+extension String {
+    /// Truncates the string so its UTF-8 byte representation does not exceed `limit`.
+    /// Cuts at extended grapheme cluster boundaries to keep multi-byte characters intact.
+    func truncated(toUTF8ByteLimit limit: Int) -> String {
+        guard limit >= 0 else { return "" }
+        guard utf8.count > limit else { return self }
+
+        var result = ""
+        var byteCount = 0
+        for character in self {
+            let characterByteCount = character.utf8.count
+            if byteCount + characterByteCount > limit {
+                break
+            }
+            byteCount += characterByteCount
+            result.append(character)
+        }
+        return result
+    }
+}
diff --git a/Mindbox/InAppMessages/InappShowFailureManager.swift b/Mindbox/InAppMessages/InappShowFailureManager.swift
@@ -16,6 +16,9 @@ protocol InappShowFailureManagerProtocol {
 }
 
 final class InappShowFailureManager: InappShowFailureManagerProtocol {
+    /// Backend payload limit for errorDetails.
+    static let errorDetailsLimit = 1000
+
     private struct InAppShowFailuresBody: Codable {
         let failures: [InAppShowFailure]
     }
@@ -36,7 +39,19 @@ final class InappShowFailureManager: InappShowFailureManagerProtocol {
             Logger.common(message: "[InappShowFailureManager] addFailure ignored, feature is disabled", category: .inAppMessages)
             return
         }
-
+
+        let truncatedDetails = details.map { original -> String in
+            let truncated = original.truncated(toUTF8ByteLimit: Self.errorDetailsLimit)
+            if truncated != original {
+                Logger.common(
+                    message: "[InappShowFailureManager] errorDetails truncated to \(truncated.utf8.count) bytes (limit \(Self.errorDetailsLimit)). inappId=\(inappId)",
+                    level: .debug,
+                    category: .inAppMessages
+                )
+            }
+            return truncated
+        }
+
         queue.async { [self] in
             if let existingIndex = failures.firstIndex(where: { $0.inappId == inappId }) {
                 guard shouldReplaceFailure(currentReason: failures[existingIndex].failureReason, newReason: reason) else {
@@ -48,13 +63,13 @@ final class InappShowFailureManager: InappShowFailureManagerProtocol {
                     )
                     return
                 }
-                failures[existingIndex] = makeFailure(inappId: inappId, reason: reason, details: details)
+                failures[existingIndex] = makeFailure(inappId: inappId, reason: reason, details: truncatedDetails)
                 Logger.common(message: "[InappShowFailureManager] Failure reason updated. inappId=\(inappId), reason=\(reason.rawValue)",
                               category: .inAppMessages)
                 return
             }
-            
-            failures.append(makeFailure(inappId: inappId, reason: reason, details: details))
+
+            failures.append(makeFailure(inappId: inappId, reason: reason, details: truncatedDetails))
         }
     }
 

diff --git a/MindboxTests/Extensions/StringExtensionsTests.swift b/MindboxTests/Extensions/StringExtensionsTests.swift
@@ -58,6 +58,23 @@ final class StringExtensionsTests: XCTestCase {
         }
     }
 
+    func test_truncatedToUTF8ByteLimit_zeroLimit_returnsEmptyString() {
+        XCTAssertEqual("hello".truncated(toUTF8ByteLimit: 0), "")
+    }
+
+    func test_truncatedToUTF8ByteLimit_zeroLimit_onEmptyString_returnsEmptyString() {
+        XCTAssertEqual("".truncated(toUTF8ByteLimit: 0), "")
+    }
+
+    func test_truncatedToUTF8ByteLimit_negativeLimit_returnsEmptyString() {
+        XCTAssertEqual("hello".truncated(toUTF8ByteLimit: -1), "")
+        XCTAssertEqual("hello".truncated(toUTF8ByteLimit: -100), "")
+    }
+
+    func test_truncatedToUTF8ByteLimit_negativeLimit_onEmptyString_returnsEmptyString() {
+        XCTAssertEqual("".truncated(toUTF8ByteLimit: -1), "")
+    }
+
     func test_parseTimeSpanToMillisNegative() throws {
         let testCases: Array = [
             "12345678901234567890.00:00:00.00",

diff --git a/MindboxTests/InApp/Tests/InappShowFailureManagerTests.swift b/MindboxTests/InApp/Tests/InappShowFailureManagerTests.swift
@@ -200,6 +200,135 @@ final class InappShowFailureManagerTests: XCTestCase {
         assertCreatedEventsCountEventually(0)
     }
 
+    func testAddFailure_errorDetailsBelowLimit_isNotTruncated() throws {
+        let details = String(repeating: "a", count: InappShowFailureManager.errorDetailsLimit - 1)
+
+        manager.addFailure(inappId: "inapp-below-limit", reason: .unknownError, details: details)
+        manager.sendFailures()
+
+        assertCreatedEventsCountEventually(1)
+        let event = try XCTUnwrap(databaseRepository.createdEvents.first)
+        let failure = try XCTUnwrap(decodeFailures(from: event)?.first)
+        XCTAssertEqual(failure.errorDetails?.count, InappShowFailureManager.errorDetailsLimit - 1)
+        XCTAssertEqual(failure.errorDetails, details)
+    }
+
+    func testAddFailure_errorDetailsAtLimit_isNotTruncated() throws {
+        let details = String(repeating: "b", count: InappShowFailureManager.errorDetailsLimit)
+
+        manager.addFailure(inappId: "inapp-at-limit", reason: .unknownError, details: details)
+        manager.sendFailures()
+
+        assertCreatedEventsCountEventually(1)
+        let event = try XCTUnwrap(databaseRepository.createdEvents.first)
+        let failure = try XCTUnwrap(decodeFailures(from: event)?.first)
+        XCTAssertEqual(failure.errorDetails?.count, InappShowFailureManager.errorDetailsLimit)
+        XCTAssertEqual(failure.errorDetails, details)
+    }
+
+    func testAddFailure_errorDetailsAboveLimit_isTruncatedToLimit() throws {
+        let limit = InappShowFailureManager.errorDetailsLimit
+        let details = String(repeating: "c", count: limit + 500)
+
+        manager.addFailure(inappId: "inapp-above-limit", reason: .unknownError, details: details)
+        manager.sendFailures()
+
+        assertCreatedEventsCountEventually(1)
+        let event = try XCTUnwrap(databaseRepository.createdEvents.first)
+        let failure = try XCTUnwrap(decodeFailures(from: event)?.first)
+        XCTAssertEqual(failure.errorDetails?.count, limit)
+        XCTAssertEqual(failure.errorDetails, String(details.prefix(limit)))
+    }
+
+    func testAddFailure_errorDetailsNil_remainsNil() throws {
+        manager.addFailure(inappId: "inapp-nil-details", reason: .unknownError, details: nil)
+        manager.sendFailures()
+
+        assertCreatedEventsCountEventually(1)
+        let event = try XCTUnwrap(databaseRepository.createdEvents.first)
+        let failure = try XCTUnwrap(decodeFailures(from: event)?.first)
+        XCTAssertNil(failure.errorDetails)
+    }
+
+    func testAddFailure_errorDetailsEmpty_remainsEmpty() throws {
+        manager.addFailure(inappId: "inapp-empty-details", reason: .unknownError, details: "")
+        manager.sendFailures()
+
+        assertCreatedEventsCountEventually(1)
+        let event = try XCTUnwrap(databaseRepository.createdEvents.first)
+        let failure = try XCTUnwrap(decodeFailures(from: event)?.first)
+        XCTAssertEqual(failure.errorDetails, "")
+    }
+
+    func testAddFailure_errorDetailsMultibyte_truncatesByUTF8Bytes() throws {
+        let limit = InappShowFailureManager.errorDetailsLimit
+        // Cyrillic 'а' is 2 bytes in UTF-8: total = 2 * limit bytes.
+        let details = String(repeating: "а", count: limit)
+
+        manager.addFailure(inappId: "inapp-multibyte", reason: .unknownError, details: details)
+        manager.sendFailures()
+
+        assertCreatedEventsCountEventually(1)
+        let event = try XCTUnwrap(databaseRepository.createdEvents.first)
+        let failure = try XCTUnwrap(decodeFailures(from: event)?.first)
+        let truncated = try XCTUnwrap(failure.errorDetails)
+
+        XCTAssertEqual(truncated.utf8.count, limit)
+        XCTAssertEqual(truncated.count, limit / 2)
+    }
+
+    func testAddFailure_errorDetailsMultibyte_doesNotSplitCharacter() throws {
+        let limit = InappShowFailureManager.errorDetailsLimit
+        let asciiPrefix = String(repeating: "x", count: limit - 1)
+        // Cyrillic 'ё' is 2 bytes — appending it would overflow by 1 byte.
+        let details = asciiPrefix + "ё"
+
+        manager.addFailure(inappId: "inapp-no-split", reason: .unknownError, details: details)
+        manager.sendFailures()
+
+        assertCreatedEventsCountEventually(1)
+        let event = try XCTUnwrap(databaseRepository.createdEvents.first)
+        let failure = try XCTUnwrap(decodeFailures(from: event)?.first)
+        let truncated = try XCTUnwrap(failure.errorDetails)
+
+        XCTAssertEqual(truncated, asciiPrefix)
+        XCTAssertEqual(truncated.utf8.count, limit - 1)
+    }
+
+    func testAddFailure_errorDetailsEmoji_isNotSplit() throws {
+        let limit = InappShowFailureManager.errorDetailsLimit
+        // "🙂" is 4 UTF-8 bytes. Fill almost to the limit, then append an emoji.
+        let asciiPrefix = String(repeating: "y", count: limit - 2)
+        let details = asciiPrefix + "🙂"
+
+        manager.addFailure(inappId: "inapp-emoji", reason: .unknownError, details: details)
+        manager.sendFailures()
+
+        assertCreatedEventsCountEventually(1)
+        let event = try XCTUnwrap(databaseRepository.createdEvents.first)
+        let failure = try XCTUnwrap(decodeFailures(from: event)?.first)
+        let truncated = try XCTUnwrap(failure.errorDetails)
+
+        XCTAssertEqual(truncated, asciiPrefix)
+        XCTAssertLessThanOrEqual(truncated.utf8.count, limit)
+    }
+
+    func testAddFailure_priorityReplacement_truncatesNewDetails() throws {
+        let limit = InappShowFailureManager.errorDetailsLimit
+        let longDetails = String(repeating: "d", count: limit + 200)
+
+        manager.addFailure(inappId: "inapp-priority-truncate", reason: .productSegmentRequestFailed, details: "short")
+        manager.addFailure(inappId: "inapp-priority-truncate", reason: .customerSegmentRequestFailed, details: longDetails)
+        manager.sendFailures()
+
+        assertCreatedEventsCountEventually(1)
+        let event = try XCTUnwrap(databaseRepository.createdEvents.first)
+        let failure = try XCTUnwrap(decodeFailures(from: event)?.first)
+        XCTAssertEqual(failure.failureReason, .customerSegmentRequestFailed)
+        XCTAssertEqual(failure.errorDetails?.count, limit)
+        XCTAssertEqual(failure.errorDetails, String(longDetails.prefix(limit)))
+    }
+
     func testSendFailures_whenFeatureDisabled_doesNotSendAndKeepsBufferedFailures() throws {
         manager.addFailure(
             inappId: "inapp-toggle-disabled",