diff --git a/lessons/m6l3-konform/build.gradle.kts b/lessons/m6l3-konform/build.gradle.kts
new file mode 100644
index 0000000..0fdc58b
--- /dev/null
+++ b/lessons/m6l3-konform/build.gradle.kts
@@ -0,0 +1,16 @@
+plugins {
+    kotlin("jvm")
+}
+
+val coroutinesVersion: String by project
+
+dependencies {
+    implementation(kotlin("stdlib"))
+
+    testImplementation(kotlin("test"))
+    testImplementation(kotlin("test-junit"))
+
+    testImplementation("io.konform:konform:0.4.0")
+    testImplementation("org.jetbrains.kotlinx:kotlinx-datetime:0.4.0")
+    testImplementation("org.jetbrains.kotlinx:kotlinx-coroutines-core:$coroutinesVersion")
+}
diff --git a/lessons/m6l3-konform/src/test/kotlin/KonformTest.kt b/lessons/m6l3-konform/src/test/kotlin/KonformTest.kt
new file mode 100644
index 0000000..b45c7ca
--- /dev/null
+++ b/lessons/m6l3-konform/src/test/kotlin/KonformTest.kt
@@ -0,0 +1,61 @@
+package ru.otus.otuskotlin.marketplace.lib.koform
+
+import io.konform.validation.Invalid
+import io.konform.validation.Validation
+import io.konform.validation.ValidationBuilder
+import io.konform.validation.jsonschema.pattern
+import kotlinx.datetime.*
+import org.junit.Test
+import kotlin.test.assertContains
+import kotlin.test.assertIs
+import kotlin.time.Duration.Companion.days
+
+// Konform - DSL для валидации
+class KonformTest {
+    @Test
+    fun konform() {
+        val objValidator = Validation<SomeObject> {
+            SomeObject::userId {
+                pattern("^[0-9a-zA-Z_-]{1,64}\$")
+            }
+            SomeObject::dob {
+                minAge(15)
+            }
+        }
+
+        val resultUserId = objValidator.validate(SomeObject())
+        assertIs<Invalid<SomeObject>>(resultUserId)
+        val errorUserId = resultUserId.errors.firstOrNull { it.dataPath == ".userId" }
+        assertContains(errorUserId?.message ?: "", "pattern")
+        println("RESULT: ${errorUserId?.dataPath} ${errorUserId?.message}")
+
+        val resultAge = objValidator.validate(SomeObject(userId = "987987987"))
+        assertIs<Invalid<SomeObject>>(resultAge)
+        val errorAge = resultAge.errors.firstOrNull { it.dataPath == ".dob" }
+        assertContains(errorAge?.message ?: "", "Age")
+        println("RESULT: ${errorAge?.dataPath} ${errorAge?.message}")
+    }
+}
+
+private fun ValidationBuilder<LocalDate?>.minAge(age: Int) = addConstraint(
+    errorMessage = "Age cannot be in range of 15..130 years",
+    "15..130"
+) {
+    if (it == null) {
+        println("EMPTY!")
+        false
+    } else {
+        val date = Clock.System
+            .now()
+            .minus((age * 365).days)
+            .toLocalDateTime(TimeZone.currentSystemDefault())
+            .date
+        println("DATE: $date ~ $it ${it.compareTo(date)}")
+        (it.compareTo(date) in 0..1)
+    }
+}
+
+data class SomeObject(
+    val userId: String = "",
+    val dob: LocalDate? = null,
+)
diff --git a/ok-marketplace-be/ok-marketplace-api-v2-kmp/src/commonMain/kotlin/mappers/MappersV2FromTransportValidated.kt b/ok-marketplace-be/ok-marketplace-api-v2-kmp/src/commonMain/kotlin/mappers/MappersV2FromTransportValidated.kt
new file mode 100644
index 0000000..9f73d52
--- /dev/null
+++ b/ok-marketplace-be/ok-marketplace-api-v2-kmp/src/commonMain/kotlin/mappers/MappersV2FromTransportValidated.kt
@@ -0,0 +1,65 @@
+package ru.otus.otuskotlin.marketplace.api.v2.mappers
+
+import ru.otus.otuskotlin.marketplace.api.v2.models.*
+import ru.otus.otuskotlin.marketplace.common.MkplContext
+import ru.otus.otuskotlin.marketplace.common.models.*
+import ru.otus.otuskotlin.marketplace.common.stubs.MkplStubs
+
+// Демонстрация форматной валидации в мапере
+private sealed interface Result<T,E>
+private data class Ok<T,E>(val value: T) : Result<T,E>
+private data class Err<T,E>(val errors: List<E>) : Result<T,E> {
+    constructor(error: E) : this(listOf(error))
+}
+
+private fun <T,E> Result<T,E>.getOrExec(default: T, block: (Err<T,E>) -> Unit = {}): T = when (this) {
+    is Ok<T,E> -> this.value
+    is Err<T,E> -> {
+        block(this)
+        default
+    }
+}
+
+@Suppress("unused")
+private fun <T,E> Result<T,E>.getOrNull(block: (Err<T,E>) -> Unit = {}): T? = when (this) {
+    is Ok<T,E> -> this.value
+    is Err<T,E> -> {
+        block(this)
+        null
+    }
+}
+
+private fun String?.transportToStubCaseValidated(): Result<MkplStubs,MkplError> = when (this) {
+    "success" -> Ok(MkplStubs.SUCCESS)
+    "notFound" -> Ok(MkplStubs.NOT_FOUND)
+    "badId" -> Ok(MkplStubs.BAD_ID)
+    "badTitle" -> Ok(MkplStubs.BAD_TITLE)
+    "badDescription" -> Ok(MkplStubs.BAD_DESCRIPTION)
+    "badVisibility" -> Ok(MkplStubs.BAD_VISIBILITY)
+    "cannotDelete" -> Ok(MkplStubs.CANNOT_DELETE)
+    "badSearchString" -> Ok(MkplStubs.BAD_SEARCH_STRING)
+    null -> Ok(MkplStubs.NONE)
+    else -> Err(
+        MkplError(
+            code = "wrong-stub-case",
+            group = "mapper-validation",
+            field = "debug.stub",
+            message = "Unsupported value for case \"$this\""
+        )
+    )
+}
+
+@Suppress("unused")
+fun MkplContext.fromTransportValidated(request: AdCreateRequest) {
+    command = MkplCommand.CREATE
+    // Вся магия здесь!
+    stubCase = request
+        .debug
+        ?.stub
+        ?.value
+        .transportToStubCaseValidated()
+        .getOrExec(MkplStubs.NONE) { err: Err<MkplStubs,MkplError> ->
+            errors.addAll(err.errors)
+            state = MkplState.FAILING
+        }
+}
diff --git a/ok-marketplace-be/ok-marketplace-api-v2-kmp/src/commonTest/kotlin/mappers/MapperValidatedTest.kt b/ok-marketplace-be/ok-marketplace-api-v2-kmp/src/commonTest/kotlin/mappers/MapperValidatedTest.kt
new file mode 100644
index 0000000..768ceb6
--- /dev/null
+++ b/ok-marketplace-be/ok-marketplace-api-v2-kmp/src/commonTest/kotlin/mappers/MapperValidatedTest.kt
@@ -0,0 +1,25 @@
+package ru.otus.otuskotlin.marketplace.api.v2.mappers
+
+import ru.otus.otuskotlin.marketplace.api.v2.models.AdCreateRequest
+import ru.otus.otuskotlin.marketplace.api.v2.models.AdDebug
+import ru.otus.otuskotlin.marketplace.api.v2.models.AdRequestDebugStubs
+import ru.otus.otuskotlin.marketplace.common.MkplContext
+import ru.otus.otuskotlin.marketplace.common.stubs.MkplStubs
+import kotlin.test.Test
+import kotlin.test.assertEquals
+
+class MapperValidatedTest {
+    @Test
+    fun fromTransportValidated() {
+        val req = AdCreateRequest(
+            debug = AdDebug(
+                stub = AdRequestDebugStubs.SUCCESS,
+            ),
+        )
+
+        val context = MkplContext()
+        context.fromTransportValidated(req)
+
+        assertEquals(MkplStubs.SUCCESS, context.stubCase)
+    }
+}
diff --git a/ok-marketplace-be/ok-marketplace-biz/src/commonMain/kotlin/MkplAdProcessor.kt b/ok-marketplace-be/ok-marketplace-biz/src/commonMain/kotlin/MkplAdProcessor.kt
index 47d9958..b73cfb9 100644
--- a/ok-marketplace-be/ok-marketplace-biz/src/commonMain/kotlin/MkplAdProcessor.kt
+++ b/ok-marketplace-be/ok-marketplace-biz/src/commonMain/kotlin/MkplAdProcessor.kt
@@ -4,10 +4,14 @@ import ru.otus.otuskotlin.marketplace.biz.general.initStatus
 import ru.otus.otuskotlin.marketplace.biz.general.operation
 import ru.otus.otuskotlin.marketplace.biz.general.stubs
 import ru.otus.otuskotlin.marketplace.biz.stubs.*
+import ru.otus.otuskotlin.marketplace.biz.validation.*
 import ru.otus.otuskotlin.marketplace.common.MkplContext
 import ru.otus.otuskotlin.marketplace.common.MkplCorSettings
+import ru.otus.otuskotlin.marketplace.common.models.MkplAdId
+import ru.otus.otuskotlin.marketplace.common.models.MkplAdLock
 import ru.otus.otuskotlin.marketplace.common.models.MkplCommand
 import ru.otus.otuskotlin.marketplace.cor.rootChain
+import ru.otus.otuskotlin.marketplace.cor.worker
 
 class MkplAdProcessor(
     private val corSettings: MkplCorSettings = MkplCorSettings.NONE
@@ -25,6 +29,18 @@ class MkplAdProcessor(
                 stubDbError("Имитация ошибки работы с БД")
                 stubNoCase("Ошибка: запрошенный стаб недопустим")
             }
+            validation {
+                worker("Копируем поля в adValidating") { adValidating = adRequest.deepCopy() }
+                worker("Очистка id") { adValidating.id = MkplAdId.NONE }
+                worker("Очистка заголовка") { adValidating.title = adValidating.title.trim() }
+                worker("Очистка описания") { adValidating.description = adValidating.description.trim() }
+                validateTitleNotEmpty("Проверка, что заголовок не пуст")
+                validateTitleHasContent("Проверка символов")
+                validateDescriptionNotEmpty("Проверка, что описание не пусто")
+                validateDescriptionHasContent("Проверка символов")
+
+                finishAdValidation("Завершение проверок")
+            }
         }
         operation("Получить объявление", MkplCommand.READ) {
             stubs("Обработка стабов") {
@@ -33,6 +49,14 @@ class MkplAdProcessor(
                 stubDbError("Имитация ошибки работы с БД")
                 stubNoCase("Ошибка: запрошенный стаб недопустим")
             }
+            validation {
+                worker("Копируем поля в adValidating") { adValidating = adRequest.deepCopy() }
+                worker("Очистка id") { adValidating.id = MkplAdId(adValidating.id.asString().trim()) }
+                validateIdNotEmpty("Проверка на непустой id")
+                validateIdProperFormat("Проверка формата id")
+
+                finishAdValidation("Успешное завершение процедуры валидации")
+            }
         }
         operation("Изменить объявление", MkplCommand.UPDATE) {
             stubs("Обработка стабов") {
@@ -43,6 +67,23 @@ class MkplAdProcessor(
                 stubDbError("Имитация ошибки работы с БД")
                 stubNoCase("Ошибка: запрошенный стаб недопустим")
             }
+            validation {
+                worker("Копируем поля в adValidating") { adValidating = adRequest.deepCopy() }
+                worker("Очистка id") { adValidating.id = MkplAdId(adValidating.id.asString().trim()) }
+                worker("Очистка lock") { adValidating.lock = MkplAdLock(adValidating.lock.asString().trim()) }
+                worker("Очистка заголовка") { adValidating.title = adValidating.title.trim() }
+                worker("Очистка описания") { adValidating.description = adValidating.description.trim() }
+                validateIdNotEmpty("Проверка на непустой id")
+                validateIdProperFormat("Проверка формата id")
+                validateLockNotEmpty("Проверка на непустой lock")
+                validateLockProperFormat("Проверка формата lock")
+                validateTitleNotEmpty("Проверка на непустой заголовок")
+                validateTitleHasContent("Проверка на наличие содержания в заголовке")
+                validateDescriptionNotEmpty("Проверка на непустое описание")
+                validateDescriptionHasContent("Проверка на наличие содержания в описании")
+
+                finishAdValidation("Успешное завершение процедуры валидации")
+            }
         }
         operation("Удалить объявление", MkplCommand.DELETE) {
             stubs("Обработка стабов") {
@@ -51,6 +92,18 @@ class MkplAdProcessor(
                 stubDbError("Имитация ошибки работы с БД")
                 stubNoCase("Ошибка: запрошенный стаб недопустим")
             }
+            validation {
+                worker("Копируем поля в adValidating") {
+                    adValidating = adRequest.deepCopy()
+                }
+                worker("Очистка id") { adValidating.id = MkplAdId(adValidating.id.asString().trim()) }
+                worker("Очистка lock") { adValidating.lock = MkplAdLock(adValidating.lock.asString().trim()) }
+                validateIdNotEmpty("Проверка на непустой id")
+                validateIdProperFormat("Проверка формата id")
+                validateLockNotEmpty("Проверка на непустой lock")
+                validateLockProperFormat("Проверка формата lock")
+                finishAdValidation("Успешное завершение процедуры валидации")
+            }
         }
         operation("Поиск объявлений", MkplCommand.SEARCH) {
             stubs("Обработка стабов") {
@@ -59,6 +112,12 @@ class MkplAdProcessor(
                 stubDbError("Имитация ошибки работы с БД")
                 stubNoCase("Ошибка: запрошенный стаб недопустим")
             }
+            validation {
+                worker("Копируем поля в adFilterValidating") { adFilterValidating = adFilterRequest.deepCopy() }
+                validateSearchStringLength("Валидация длины строки поиска в фильтре")
+
+                finishAdFilterValidation("Успешное завершение процедуры валидации")
+            }
         }
         operation("Поиск подходящих предложений для объявления", MkplCommand.OFFERS) {
             stubs("Обработка стабов") {
@@ -67,6 +126,15 @@ class MkplAdProcessor(
                 stubDbError("Имитация ошибки работы с БД")
                 stubNoCase("Ошибка: запрошенный стаб недопустим")
             }
+            validation {
+                worker("Копируем поля в adValidating") { adValidating = adRequest.deepCopy() }
+                worker("Очистка id") { adValidating.id = MkplAdId(adValidating.id.asString().trim()) }
+                validateIdNotEmpty("Проверка на непустой id")
+                validateIdProperFormat("Проверка формата id")
+
+                finishAdValidation("Успешное завершение процедуры валидации")
+            }
         }
     }.build()
 }
+
diff --git a/ok-marketplace-be/ok-marketplace-biz/src/commonMain/kotlin/validation/FinishValidation.kt b/ok-marketplace-be/ok-marketplace-biz/src/commonMain/kotlin/validation/FinishValidation.kt
new file mode 100644
index 0000000..08feabd
--- /dev/null
+++ b/ok-marketplace-be/ok-marketplace-biz/src/commonMain/kotlin/validation/FinishValidation.kt
@@ -0,0 +1,22 @@
+package ru.otus.otuskotlin.marketplace.biz.validation
+
+import ru.otus.otuskotlin.marketplace.common.MkplContext
+import ru.otus.otuskotlin.marketplace.common.models.MkplState
+import ru.otus.otuskotlin.marketplace.cor.ICorChainDsl
+import ru.otus.otuskotlin.marketplace.cor.worker
+
+fun ICorChainDsl<MkplContext>.finishAdValidation(title: String) = worker {
+    this.title = title
+    on { state == MkplState.RUNNING }
+    handle {
+        adValidated = adValidating
+    }
+}
+
+fun ICorChainDsl<MkplContext>.finishAdFilterValidation(title: String) = worker {
+    this.title = title
+    on { state == MkplState.RUNNING }
+    handle {
+        adFilterValidated = adFilterValidating
+    }
+}
diff --git a/ok-marketplace-be/ok-marketplace-biz/src/commonMain/kotlin/validation/ValidateDescriptionHasContent.kt b/ok-marketplace-be/ok-marketplace-biz/src/commonMain/kotlin/validation/ValidateDescriptionHasContent.kt
new file mode 100644
index 0000000..3f3402e
--- /dev/null
+++ b/ok-marketplace-be/ok-marketplace-biz/src/commonMain/kotlin/validation/ValidateDescriptionHasContent.kt
@@ -0,0 +1,23 @@
+package ru.otus.otuskotlin.marketplace.biz.validation
+
+import ru.otus.otuskotlin.marketplace.common.helpers.errorValidation
+import ru.otus.otuskotlin.marketplace.common.MkplContext
+import ru.otus.otuskotlin.marketplace.common.helpers.fail
+import ru.otus.otuskotlin.marketplace.cor.ICorChainDsl
+import ru.otus.otuskotlin.marketplace.cor.worker
+
+// пример обработки ошибки в рамках бизнес-цепочки
+fun ICorChainDsl<MkplContext>.validateDescriptionHasContent(title: String) = worker {
+    this.title = title
+    val regExp = Regex("\\p{L}")
+    on { adValidating.description.isNotEmpty() && !adValidating.description.contains(regExp) }
+    handle {
+        fail(
+            errorValidation(
+                field = "description",
+                violationCode = "noContent",
+                description = "field must contain letters"
+            )
+        )
+    }
+}
diff --git a/ok-marketplace-be/ok-marketplace-biz/src/commonMain/kotlin/validation/ValidateDescriptionNotEmpty.kt b/ok-marketplace-be/ok-marketplace-biz/src/commonMain/kotlin/validation/ValidateDescriptionNotEmpty.kt
new file mode 100644
index 0000000..2ffac6f
--- /dev/null
+++ b/ok-marketplace-be/ok-marketplace-biz/src/commonMain/kotlin/validation/ValidateDescriptionNotEmpty.kt
@@ -0,0 +1,21 @@
+package ru.otus.otuskotlin.marketplace.biz.validation
+
+import ru.otus.otuskotlin.marketplace.cor.ICorChainDsl
+import ru.otus.otuskotlin.marketplace.cor.worker
+import ru.otus.otuskotlin.marketplace.common.helpers.errorValidation
+import ru.otus.otuskotlin.marketplace.common.MkplContext
+import ru.otus.otuskotlin.marketplace.common.helpers.fail
+
+fun ICorChainDsl<MkplContext>.validateDescriptionNotEmpty(title: String) = worker {
+    this.title = title
+    on { adValidating.description.isEmpty() }
+    handle {
+        fail(
+            errorValidation(
+            field = "description",
+            violationCode = "empty",
+            description = "field must not be empty"
+        )
+        )
+    }
+}
diff --git a/ok-marketplace-be/ok-marketplace-biz/src/commonMain/kotlin/validation/ValidateIdNotEmpty.kt b/ok-marketplace-be/ok-marketplace-biz/src/commonMain/kotlin/validation/ValidateIdNotEmpty.kt
new file mode 100644
index 0000000..9b2d505
--- /dev/null
+++ b/ok-marketplace-be/ok-marketplace-biz/src/commonMain/kotlin/validation/ValidateIdNotEmpty.kt
@@ -0,0 +1,21 @@
+package ru.otus.otuskotlin.marketplace.biz.validation
+
+import ru.otus.otuskotlin.marketplace.cor.ICorChainDsl
+import ru.otus.otuskotlin.marketplace.cor.worker
+import ru.otus.otuskotlin.marketplace.common.helpers.errorValidation
+import ru.otus.otuskotlin.marketplace.common.MkplContext
+import ru.otus.otuskotlin.marketplace.common.helpers.fail
+
+fun ICorChainDsl<MkplContext>.validateIdNotEmpty(title: String) = worker {
+    this.title = title
+    on { adValidating.id.asString().isEmpty() }
+    handle {
+        fail(
+            errorValidation(
+                field = "id",
+                violationCode = "empty",
+                description = "field must not be empty"
+            )
+        )
+    }
+}
diff --git a/ok-marketplace-be/ok-marketplace-biz/src/commonMain/kotlin/validation/ValidateIdProperFormat.kt b/ok-marketplace-be/ok-marketplace-biz/src/commonMain/kotlin/validation/ValidateIdProperFormat.kt
new file mode 100644
index 0000000..ecb48a1
--- /dev/null
+++ b/ok-marketplace-be/ok-marketplace-biz/src/commonMain/kotlin/validation/ValidateIdProperFormat.kt
@@ -0,0 +1,28 @@
+package ru.otus.otuskotlin.marketplace.biz.validation
+
+import ru.otus.otuskotlin.marketplace.cor.ICorChainDsl
+import ru.otus.otuskotlin.marketplace.cor.worker
+import ru.otus.otuskotlin.marketplace.common.helpers.errorValidation
+import ru.otus.otuskotlin.marketplace.common.MkplContext
+import ru.otus.otuskotlin.marketplace.common.helpers.fail
+import ru.otus.otuskotlin.marketplace.common.models.MkplAdId
+
+fun ICorChainDsl<MkplContext>.validateIdProperFormat(title: String) = worker {
+    this.title = title
+
+    // Может быть вынесен в MkplAdId для реализации различных форматов
+    val regExp = Regex("^[0-9a-zA-Z#:-]+$")
+    on { adValidating.id != MkplAdId.NONE && ! adValidating.id.asString().matches(regExp) }
+    handle {
+        val encodedId = adValidating.id.asString()
+            .replace("<", "&lt;")
+            .replace(">", "&gt;")
+        fail(
+            errorValidation(
+            field = "id",
+            violationCode = "badFormat",
+            description = "value $encodedId must contain only letters and numbers"
+        )
+        )
+    }
+}
diff --git a/ok-marketplace-be/ok-marketplace-biz/src/commonMain/kotlin/validation/ValidateLockNotEmpty.kt b/ok-marketplace-be/ok-marketplace-biz/src/commonMain/kotlin/validation/ValidateLockNotEmpty.kt
new file mode 100644
index 0000000..6dee777
--- /dev/null
+++ b/ok-marketplace-be/ok-marketplace-biz/src/commonMain/kotlin/validation/ValidateLockNotEmpty.kt
@@ -0,0 +1,21 @@
+package ru.otus.otuskotlin.marketplace.biz.validation
+
+import ru.otus.otuskotlin.marketplace.common.helpers.errorValidation
+import ru.otus.otuskotlin.marketplace.common.MkplContext
+import ru.otus.otuskotlin.marketplace.common.helpers.fail
+import ru.otus.otuskotlin.marketplace.cor.ICorChainDsl
+import ru.otus.otuskotlin.marketplace.cor.worker
+
+fun ICorChainDsl<MkplContext>.validateLockNotEmpty(title: String) = worker {
+    this.title = title
+    on { adValidating.lock.asString().isEmpty() }
+    handle {
+        fail(
+            errorValidation(
+                field = "lock",
+                violationCode = "empty",
+                description = "field must not be empty"
+            )
+        )
+    }
+}
diff --git a/ok-marketplace-be/ok-marketplace-biz/src/commonMain/kotlin/validation/ValidateLockProperFormat.kt b/ok-marketplace-be/ok-marketplace-biz/src/commonMain/kotlin/validation/ValidateLockProperFormat.kt
new file mode 100644
index 0000000..7252b66
--- /dev/null
+++ b/ok-marketplace-be/ok-marketplace-biz/src/commonMain/kotlin/validation/ValidateLockProperFormat.kt
@@ -0,0 +1,26 @@
+package ru.otus.otuskotlin.marketplace.biz.validation
+
+import ru.otus.otuskotlin.marketplace.common.MkplContext
+import ru.otus.otuskotlin.marketplace.common.helpers.errorValidation
+import ru.otus.otuskotlin.marketplace.common.helpers.fail
+import ru.otus.otuskotlin.marketplace.common.models.MkplAdLock
+import ru.otus.otuskotlin.marketplace.cor.ICorChainDsl
+import ru.otus.otuskotlin.marketplace.cor.worker
+
+fun ICorChainDsl<MkplContext>.validateLockProperFormat(title: String) = worker {
+    this.title = title
+
+    // Может быть вынесен в MkplAdId для реализации различных форматов
+    val regExp = Regex("^[0-9a-zA-Z-]+$")
+    on { adValidating.lock != MkplAdLock.NONE && !adValidating.lock.asString().matches(regExp) }
+    handle {
+        val encodedId = adValidating.lock.asString()
+        fail(
+            errorValidation(
+                field = "lock",
+                violationCode = "badFormat",
+                description = "value $encodedId must contain only"
+            )
+        )
+    }
+}
diff --git a/ok-marketplace-be/ok-marketplace-biz/src/commonMain/kotlin/validation/ValidateSearchStringLength.kt b/ok-marketplace-be/ok-marketplace-biz/src/commonMain/kotlin/validation/ValidateSearchStringLength.kt
new file mode 100644
index 0000000..cbaccab
--- /dev/null
+++ b/ok-marketplace-be/ok-marketplace-biz/src/commonMain/kotlin/validation/ValidateSearchStringLength.kt
@@ -0,0 +1,49 @@
+package ru.otus.otuskotlin.marketplace.biz.validation
+
+import ru.otus.otuskotlin.marketplace.common.MkplContext
+import ru.otus.otuskotlin.marketplace.common.helpers.errorValidation
+import ru.otus.otuskotlin.marketplace.common.helpers.fail
+import ru.otus.otuskotlin.marketplace.common.models.MkplState
+import ru.otus.otuskotlin.marketplace.cor.ICorChainDsl
+import ru.otus.otuskotlin.marketplace.cor.chain
+import ru.otus.otuskotlin.marketplace.cor.worker
+
+fun ICorChainDsl<MkplContext>.validateSearchStringLength(title: String) = chain {
+    this.title = title
+    this.description = """
+        Валидация длины строки поиска в поисковых фильтрах. Допустимые значения:
+        - null - не выполняем поиск по строке
+        - 3-100 - допустимая длина
+        - больше 100 - слишком длинная строка
+    """.trimIndent()
+    on { state == MkplState.RUNNING }
+    worker("Обрезка пустых символов") { adFilterValidating.searchString = adFilterValidating.searchString.trim() }
+    worker {
+        this.title = "Проверка кейса длины на 0-2 символа"
+        this.description = this.title
+        on { state == MkplState.RUNNING && adFilterValidating.searchString.length in (1..2) }
+        handle {
+            fail(
+                errorValidation(
+                    field = "searchString",
+                    violationCode = "tooShort",
+                    description = "Search string must contain at least 3 symbols"
+                )
+            )
+        }
+    }
+    worker {
+        this.title = "Проверка кейса длины на более 100 символов"
+        this.description = this.title
+        on { state == MkplState.RUNNING && adFilterValidating.searchString.length > 100 }
+        handle {
+            fail(
+                errorValidation(
+                    field = "searchString",
+                    violationCode = "tooLong",
+                    description = "Search string must be no more than 100 symbols long"
+                )
+            )
+        }
+    }
+}
diff --git a/ok-marketplace-be/ok-marketplace-biz/src/commonMain/kotlin/validation/ValidateTitleHasContent.kt b/ok-marketplace-be/ok-marketplace-biz/src/commonMain/kotlin/validation/ValidateTitleHasContent.kt
new file mode 100644
index 0000000..0f6c02c
--- /dev/null
+++ b/ok-marketplace-be/ok-marketplace-biz/src/commonMain/kotlin/validation/ValidateTitleHasContent.kt
@@ -0,0 +1,26 @@
+package ru.otus.otuskotlin.marketplace.biz.validation
+
+import ru.otus.otuskotlin.marketplace.cor.ICorChainDsl
+import ru.otus.otuskotlin.marketplace.cor.worker
+import ru.otus.otuskotlin.marketplace.common.helpers.errorValidation
+import ru.otus.otuskotlin.marketplace.common.MkplContext
+import ru.otus.otuskotlin.marketplace.common.helpers.fail
+
+fun ICorChainDsl<MkplContext>.validateTitleHasContent(title: String) = worker {
+    this.title = title
+    this.description = """
+        Проверяем, что у нас есть какие-то слова в заголовке.
+        Отказываем в публикации заголовков, в которых только бессмысленные символы типа %^&^$^%#^))&^*&%^^&
+    """.trimIndent()
+    val regExp = Regex("\\p{L}")
+    on { adValidating.title.isNotEmpty() && ! adValidating.title.contains(regExp) }
+    handle {
+        fail(
+            errorValidation(
+            field = "title",
+            violationCode = "noContent",
+            description = "field must contain letters"
+        )
+        )
+    }
+}
diff --git a/ok-marketplace-be/ok-marketplace-biz/src/commonMain/kotlin/validation/ValidateTitleNotEmpty.kt b/ok-marketplace-be/ok-marketplace-biz/src/commonMain/kotlin/validation/ValidateTitleNotEmpty.kt
new file mode 100644
index 0000000..75df4ac
--- /dev/null
+++ b/ok-marketplace-be/ok-marketplace-biz/src/commonMain/kotlin/validation/ValidateTitleNotEmpty.kt
@@ -0,0 +1,22 @@
+package ru.otus.otuskotlin.marketplace.biz.validation
+
+import ru.otus.otuskotlin.marketplace.cor.ICorChainDsl
+import ru.otus.otuskotlin.marketplace.cor.worker
+import ru.otus.otuskotlin.marketplace.common.helpers.errorValidation
+import ru.otus.otuskotlin.marketplace.common.MkplContext
+import ru.otus.otuskotlin.marketplace.common.helpers.fail
+
+// смотрим пример COR DSL валидации
+fun ICorChainDsl<MkplContext>.validateTitleNotEmpty(title: String) = worker {
+    this.title = title
+    on { adValidating.title.isEmpty() }
+    handle {
+        fail(
+            errorValidation(
+                field = "title",
+                violationCode = "empty",
+                description = "field must not be empty"
+            )
+        )
+    }
+}
diff --git a/ok-marketplace-be/ok-marketplace-biz/src/commonMain/kotlin/validation/Validation.kt b/ok-marketplace-be/ok-marketplace-biz/src/commonMain/kotlin/validation/Validation.kt
new file mode 100644
index 0000000..65ed1d3
--- /dev/null
+++ b/ok-marketplace-be/ok-marketplace-biz/src/commonMain/kotlin/validation/Validation.kt
@@ -0,0 +1,13 @@
+package ru.otus.otuskotlin.marketplace.biz.validation
+
+import ru.otus.otuskotlin.marketplace.common.MkplContext
+import ru.otus.otuskotlin.marketplace.common.models.MkplState
+import ru.otus.otuskotlin.marketplace.cor.ICorChainDsl
+import ru.otus.otuskotlin.marketplace.cor.chain
+
+fun ICorChainDsl<MkplContext>.validation(block: ICorChainDsl<MkplContext>.() -> Unit) = chain {
+    block()
+    title = "Валидация"
+
+    on { state == MkplState.RUNNING }
+}
diff --git a/ok-marketplace-be/ok-marketplace-biz/src/commonTest/kotlin/validation/BaseBizValidationTest.kt b/ok-marketplace-be/ok-marketplace-biz/src/commonTest/kotlin/validation/BaseBizValidationTest.kt
new file mode 100644
index 0000000..46fb23e
--- /dev/null
+++ b/ok-marketplace-be/ok-marketplace-biz/src/commonTest/kotlin/validation/BaseBizValidationTest.kt
@@ -0,0 +1,11 @@
+package ru.otus.otuskotlin.marketplace.biz.validation
+
+import ru.otus.otuskotlin.marketplace.biz.MkplAdProcessor
+import ru.otus.otuskotlin.marketplace.common.MkplCorSettings
+import ru.otus.otuskotlin.marketplace.common.models.MkplCommand
+
+abstract class BaseBizValidationTest {
+    protected abstract val command: MkplCommand
+    private val settings by lazy { MkplCorSettings() }
+    protected val processor by lazy { MkplAdProcessor(settings) }
+}
diff --git a/ok-marketplace-be/ok-marketplace-biz/src/commonTest/kotlin/validation/BizValidationCreateTest.kt b/ok-marketplace-be/ok-marketplace-biz/src/commonTest/kotlin/validation/BizValidationCreateTest.kt
new file mode 100644
index 0000000..ba85652
--- /dev/null
+++ b/ok-marketplace-be/ok-marketplace-biz/src/commonTest/kotlin/validation/BizValidationCreateTest.kt
@@ -0,0 +1,19 @@
+package ru.otus.otuskotlin.marketplace.biz.validation
+
+import ru.otus.otuskotlin.marketplace.common.models.MkplCommand
+import kotlin.test.Test
+
+// смотрим пример теста валидации, собранного из тестовых функций-оберток
+class BizValidationCreateTest: BaseBizValidationTest() {
+    override val command: MkplCommand = MkplCommand.CREATE
+
+    @Test fun correctTitle() = validationTitleCorrect(command, processor)
+    @Test fun trimTitle() = validationTitleTrim(command, processor)
+    @Test fun emptyTitle() = validationTitleEmpty(command, processor)
+    @Test fun badSymbolsTitle() = validationTitleSymbols(command, processor)
+
+    @Test fun correctDescription() = validationDescriptionCorrect(command, processor)
+    @Test fun trimDescription() = validationDescriptionTrim(command, processor)
+    @Test fun emptyDescription() = validationDescriptionEmpty(command, processor)
+    @Test fun badSymbolsDescription() = validationDescriptionSymbols(command, processor)
+}
diff --git a/ok-marketplace-be/ok-marketplace-biz/src/commonTest/kotlin/validation/BizValidationDeleteTest.kt b/ok-marketplace-be/ok-marketplace-biz/src/commonTest/kotlin/validation/BizValidationDeleteTest.kt
new file mode 100644
index 0000000..f31f6cc
--- /dev/null
+++ b/ok-marketplace-be/ok-marketplace-biz/src/commonTest/kotlin/validation/BizValidationDeleteTest.kt
@@ -0,0 +1,23 @@
+package ru.otus.otuskotlin.marketplace.biz.validation
+
+import ru.otus.otuskotlin.marketplace.common.models.MkplCommand
+import validation.validationLockCorrect
+import validation.validationLockEmpty
+import validation.validationLockFormat
+import validation.validationLockTrim
+import kotlin.test.Test
+
+class BizValidationDeleteTest: BaseBizValidationTest() {
+    override val command = MkplCommand.DELETE
+
+    @Test fun correctId() = validationIdCorrect(command, processor)
+    @Test fun trimId() = validationIdTrim(command, processor)
+    @Test fun emptyId() = validationIdEmpty(command, processor)
+    @Test fun badFormatId() = validationIdFormat(command, processor)
+
+    @Test fun correctLock() = validationLockCorrect(command, processor)
+    @Test fun trimLock() = validationLockTrim(command, processor)
+    @Test fun emptyLock() = validationLockEmpty(command, processor)
+    @Test fun badFormatLock() = validationLockFormat(command, processor)
+
+}
diff --git a/ok-marketplace-be/ok-marketplace-biz/src/commonTest/kotlin/validation/BizValidationOffersTest.kt b/ok-marketplace-be/ok-marketplace-biz/src/commonTest/kotlin/validation/BizValidationOffersTest.kt
new file mode 100644
index 0000000..5d3293c
--- /dev/null
+++ b/ok-marketplace-be/ok-marketplace-biz/src/commonTest/kotlin/validation/BizValidationOffersTest.kt
@@ -0,0 +1,14 @@
+package ru.otus.otuskotlin.marketplace.biz.validation
+
+import ru.otus.otuskotlin.marketplace.common.models.MkplCommand
+import kotlin.test.Test
+
+class BizValidationOffersTest: BaseBizValidationTest() {
+    override val command = MkplCommand.OFFERS
+
+    @Test fun correctId() = validationIdCorrect(command, processor)
+    @Test fun trimId() = validationIdTrim(command, processor)
+    @Test fun emptyId() = validationIdEmpty(command, processor)
+    @Test fun badFormatId() = validationIdFormat(command, processor)
+
+}
diff --git a/ok-marketplace-be/ok-marketplace-biz/src/commonTest/kotlin/validation/BizValidationReadTest.kt b/ok-marketplace-be/ok-marketplace-biz/src/commonTest/kotlin/validation/BizValidationReadTest.kt
new file mode 100644
index 0000000..e9a325b
--- /dev/null
+++ b/ok-marketplace-be/ok-marketplace-biz/src/commonTest/kotlin/validation/BizValidationReadTest.kt
@@ -0,0 +1,14 @@
+package ru.otus.otuskotlin.marketplace.biz.validation
+
+import ru.otus.otuskotlin.marketplace.common.models.MkplCommand
+import kotlin.test.Test
+
+class BizValidationReadTest: BaseBizValidationTest() {
+    override val command = MkplCommand.READ
+
+    @Test fun correctId() = validationIdCorrect(command, processor)
+    @Test fun trimId() = validationIdTrim(command, processor)
+    @Test fun emptyId() = validationIdEmpty(command, processor)
+    @Test fun badFormatId() = validationIdFormat(command, processor)
+
+}
diff --git a/ok-marketplace-be/ok-marketplace-biz/src/commonTest/kotlin/validation/BizValidationSearchTest.kt b/ok-marketplace-be/ok-marketplace-biz/src/commonTest/kotlin/validation/BizValidationSearchTest.kt
new file mode 100644
index 0000000..e27ca9b
--- /dev/null
+++ b/ok-marketplace-be/ok-marketplace-biz/src/commonTest/kotlin/validation/BizValidationSearchTest.kt
@@ -0,0 +1,28 @@
+package ru.otus.otuskotlin.marketplace.biz.validation
+
+import kotlinx.coroutines.test.runTest
+import ru.otus.otuskotlin.marketplace.common.MkplContext
+import ru.otus.otuskotlin.marketplace.common.models.MkplAdFilter
+import ru.otus.otuskotlin.marketplace.common.models.MkplCommand
+import ru.otus.otuskotlin.marketplace.common.models.MkplState
+import ru.otus.otuskotlin.marketplace.common.models.MkplWorkMode
+import kotlin.test.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertNotEquals
+
+class BizValidationSearchTest: BaseBizValidationTest() {
+    override val command = MkplCommand.SEARCH
+
+    @Test
+    fun correctEmpty() = runTest {
+        val ctx = MkplContext(
+            command = command,
+            state = MkplState.NONE,
+            workMode = MkplWorkMode.TEST,
+            adFilterRequest = MkplAdFilter()
+        )
+        processor.exec(ctx)
+        assertEquals(0, ctx.errors.size)
+        assertNotEquals(MkplState.FAILING, ctx.state)
+    }
+}
diff --git a/ok-marketplace-be/ok-marketplace-biz/src/commonTest/kotlin/validation/BizValidationUpdateTest.kt b/ok-marketplace-be/ok-marketplace-biz/src/commonTest/kotlin/validation/BizValidationUpdateTest.kt
new file mode 100644
index 0000000..ae1e29e
--- /dev/null
+++ b/ok-marketplace-be/ok-marketplace-biz/src/commonTest/kotlin/validation/BizValidationUpdateTest.kt
@@ -0,0 +1,33 @@
+package ru.otus.otuskotlin.marketplace.biz.validation
+
+import ru.otus.otuskotlin.marketplace.common.models.MkplCommand
+import validation.validationLockCorrect
+import validation.validationLockEmpty
+import validation.validationLockFormat
+import validation.validationLockTrim
+import kotlin.test.Test
+
+class BizValidationUpdateTest: BaseBizValidationTest() {
+    override val command = MkplCommand.UPDATE
+
+    @Test fun correctTitle() = validationTitleCorrect(command, processor)
+    @Test fun trimTitle() = validationTitleTrim(command, processor)
+    @Test fun emptyTitle() = validationTitleEmpty(command, processor)
+    @Test fun badSymbolsTitle() = validationTitleSymbols(command, processor)
+
+    @Test fun correctDescription() = validationDescriptionCorrect(command, processor)
+    @Test fun trimDescription() = validationDescriptionTrim(command, processor)
+    @Test fun emptyDescription() = validationDescriptionEmpty(command, processor)
+    @Test fun badSymbolsDescription() = validationDescriptionSymbols(command, processor)
+
+    @Test fun correctId() = validationIdCorrect(command, processor)
+    @Test fun trimId() = validationIdTrim(command, processor)
+    @Test fun emptyId() = validationIdEmpty(command, processor)
+    @Test fun badFormatId() = validationIdFormat(command, processor)
+
+    @Test fun correctLock() = validationLockCorrect(command, processor)
+    @Test fun trimLock() = validationLockTrim(command, processor)
+    @Test fun emptyLock() = validationLockEmpty(command, processor)
+    @Test fun badFormatLock() = validationLockFormat(command, processor)
+
+}
diff --git a/ok-marketplace-be/ok-marketplace-biz/src/commonTest/kotlin/validation/ValidateSearchStringLengthTest.kt b/ok-marketplace-be/ok-marketplace-biz/src/commonTest/kotlin/validation/ValidateSearchStringLengthTest.kt
new file mode 100644
index 0000000..c651425
--- /dev/null
+++ b/ok-marketplace-be/ok-marketplace-biz/src/commonTest/kotlin/validation/ValidateSearchStringLengthTest.kt
@@ -0,0 +1,59 @@
+package ru.otus.otuskotlin.marketplace.biz.validation
+
+import kotlinx.coroutines.test.runTest
+import ru.otus.otuskotlin.marketplace.common.MkplContext
+import ru.otus.otuskotlin.marketplace.common.models.MkplAdFilter
+import ru.otus.otuskotlin.marketplace.common.models.MkplState
+import ru.otus.otuskotlin.marketplace.cor.rootChain
+import kotlin.test.Test
+import kotlin.test.assertEquals
+
+class ValidateSearchStringLengthTest {
+    @Test
+    fun emptyString() = runTest {
+        val ctx = MkplContext(state = MkplState.RUNNING, adFilterValidating = MkplAdFilter(searchString = ""))
+        chain.exec(ctx)
+        assertEquals(MkplState.RUNNING, ctx.state)
+        assertEquals(0, ctx.errors.size)
+    }
+
+    @Test
+    fun blankString() = runTest {
+        val ctx = MkplContext(state = MkplState.RUNNING, adFilterValidating = MkplAdFilter(searchString = "  "))
+        chain.exec(ctx)
+        assertEquals(MkplState.RUNNING, ctx.state)
+        assertEquals(0, ctx.errors.size)
+    }
+
+    @Test
+    fun shortString() = runTest {
+        val ctx = MkplContext(state = MkplState.RUNNING, adFilterValidating = MkplAdFilter(searchString = "12"))
+        chain.exec(ctx)
+        assertEquals(MkplState.FAILING, ctx.state)
+        assertEquals(1, ctx.errors.size)
+        assertEquals("validation-searchString-tooShort", ctx.errors.first().code)
+    }
+
+    @Test
+    fun normalString() = runTest {
+        val ctx = MkplContext(state = MkplState.RUNNING, adFilterValidating = MkplAdFilter(searchString = "123"))
+        chain.exec(ctx)
+        assertEquals(MkplState.RUNNING, ctx.state)
+        assertEquals(0, ctx.errors.size)
+    }
+
+    @Test
+    fun longString() = runTest {
+        val ctx = MkplContext(state = MkplState.RUNNING, adFilterValidating = MkplAdFilter(searchString = "12".repeat(51)))
+        chain.exec(ctx)
+        assertEquals(MkplState.FAILING, ctx.state)
+        assertEquals(1, ctx.errors.size)
+        assertEquals("validation-searchString-tooLong", ctx.errors.first().code)
+    }
+
+    companion object {
+        val chain = rootChain {
+            validateSearchStringLength("")
+        }.build()
+    }
+}
diff --git a/ok-marketplace-be/ok-marketplace-biz/src/commonTest/kotlin/validation/ValidateTitleHasContentTest.kt b/ok-marketplace-be/ok-marketplace-biz/src/commonTest/kotlin/validation/ValidateTitleHasContentTest.kt
new file mode 100644
index 0000000..51f4e0d
--- /dev/null
+++ b/ok-marketplace-be/ok-marketplace-biz/src/commonTest/kotlin/validation/ValidateTitleHasContentTest.kt
@@ -0,0 +1,43 @@
+package ru.otus.otuskotlin.marketplace.biz.validation
+
+import kotlinx.coroutines.test.runTest
+import ru.otus.otuskotlin.marketplace.common.MkplContext
+import ru.otus.otuskotlin.marketplace.common.models.MkplAd
+import ru.otus.otuskotlin.marketplace.common.models.MkplAdFilter
+import ru.otus.otuskotlin.marketplace.common.models.MkplState
+import ru.otus.otuskotlin.marketplace.cor.rootChain
+import kotlin.test.Test
+import kotlin.test.assertEquals
+
+class ValidateTitleHasContentTest {
+    @Test
+    fun emptyString() = runTest {
+        val ctx = MkplContext(state = MkplState.RUNNING, adValidating = MkplAd(title = ""))
+        chain.exec(ctx)
+        assertEquals(MkplState.RUNNING, ctx.state)
+        assertEquals(0, ctx.errors.size)
+    }
+
+    @Test
+    fun noContent() = runTest {
+        val ctx = MkplContext(state = MkplState.RUNNING, adValidating = MkplAd(title = "12!@#$%^&*()_+-="))
+        chain.exec(ctx)
+        assertEquals(MkplState.FAILING, ctx.state)
+        assertEquals(1, ctx.errors.size)
+        assertEquals("validation-title-noContent", ctx.errors.first().code)
+    }
+
+    @Test
+    fun normalString() = runTest {
+        val ctx = MkplContext(state = MkplState.RUNNING, adFilterValidating = MkplAdFilter(searchString = "Ж"))
+        chain.exec(ctx)
+        assertEquals(MkplState.RUNNING, ctx.state)
+        assertEquals(0, ctx.errors.size)
+    }
+
+    companion object {
+        val chain = rootChain {
+            validateTitleHasContent("")
+        }.build()
+    }
+}
diff --git a/ok-marketplace-be/ok-marketplace-biz/src/commonTest/kotlin/validation/ValidationBadDescription.kt b/ok-marketplace-be/ok-marketplace-biz/src/commonTest/kotlin/validation/ValidationBadDescription.kt
new file mode 100644
index 0000000..06b9153
--- /dev/null
+++ b/ok-marketplace-be/ok-marketplace-biz/src/commonTest/kotlin/validation/ValidationBadDescription.kt
@@ -0,0 +1,96 @@
+package ru.otus.otuskotlin.marketplace.biz.validation
+
+import kotlinx.coroutines.test.runTest
+import ru.otus.otuskotlin.marketplace.biz.MkplAdProcessor
+import ru.otus.otuskotlin.marketplace.common.MkplContext
+import ru.otus.otuskotlin.marketplace.common.models.*
+import ru.otus.otuskotlin.marketplace.stubs.MkplAdStub
+import kotlin.test.assertContains
+import kotlin.test.assertEquals
+import kotlin.test.assertNotEquals
+
+private val stub = MkplAdStub.get()
+
+fun validationDescriptionCorrect(command: MkplCommand, processor: MkplAdProcessor) = runTest {
+    val ctx = MkplContext(
+        command = command,
+        state = MkplState.NONE,
+        workMode = MkplWorkMode.TEST,
+        adRequest = MkplAd(
+            id = stub.id,
+            title = "abc",
+            description = "abc",
+            adType = MkplDealSide.DEMAND,
+            visibility = MkplVisibility.VISIBLE_PUBLIC,
+            lock = MkplAdLock("123-234-abc-ABC"),
+        ),
+    )
+    processor.exec(ctx)
+    assertEquals(0, ctx.errors.size)
+    assertNotEquals(MkplState.FAILING, ctx.state)
+    assertEquals("abc", ctx.adValidated.description)
+}
+
+fun validationDescriptionTrim(command: MkplCommand, processor: MkplAdProcessor) = runTest {
+    val ctx = MkplContext(
+        command = command,
+        state = MkplState.NONE,
+        workMode = MkplWorkMode.TEST,
+        adRequest = MkplAd(
+            id = stub.id,
+            title = "abc",
+            description = " \n\tabc \n\t",
+            adType = MkplDealSide.DEMAND,
+            visibility = MkplVisibility.VISIBLE_PUBLIC,
+            lock = MkplAdLock("123-234-abc-ABC"),
+        ),
+    )
+    processor.exec(ctx)
+    assertEquals(0, ctx.errors.size)
+    assertNotEquals(MkplState.FAILING, ctx.state)
+    assertEquals("abc", ctx.adValidated.description)
+}
+
+fun validationDescriptionEmpty(command: MkplCommand, processor: MkplAdProcessor) = runTest {
+    val ctx = MkplContext(
+        command = command,
+        state = MkplState.NONE,
+        workMode = MkplWorkMode.TEST,
+        adRequest = MkplAd(
+            id = stub.id,
+            title = "abc",
+            description = "",
+            adType = MkplDealSide.DEMAND,
+            visibility = MkplVisibility.VISIBLE_PUBLIC,
+            lock = MkplAdLock("123-234-abc-ABC"),
+        ),
+    )
+    processor.exec(ctx)
+    assertEquals(1, ctx.errors.size)
+    assertEquals(MkplState.FAILING, ctx.state)
+    val error = ctx.errors.firstOrNull()
+    assertEquals("description", error?.field)
+    assertContains(error?.message ?: "", "description")
+}
+
+fun validationDescriptionSymbols(command: MkplCommand, processor: MkplAdProcessor) = runTest {
+    val ctx = MkplContext(
+        command = command,
+        state = MkplState.NONE,
+        workMode = MkplWorkMode.TEST,
+        adRequest = MkplAd(
+            id = stub.id,
+            title = "abc",
+            description = "!@#$%^&*(),.{}",
+            adType = MkplDealSide.DEMAND,
+            visibility = MkplVisibility.VISIBLE_PUBLIC,
+            lock = MkplAdLock("123-234-abc-ABC"),
+        ),
+    )
+    processor.exec(ctx)
+    assertEquals(1, ctx.errors.size)
+    assertEquals(MkplState.FAILING, ctx.state)
+    val error = ctx.errors.firstOrNull()
+    assertEquals("description", error?.field)
+    assertContains(error?.message ?: "", "description")
+}
diff --git a/ok-marketplace-be/ok-marketplace-biz/src/commonTest/kotlin/validation/ValidationBadId.kt b/ok-marketplace-be/ok-marketplace-biz/src/commonTest/kotlin/validation/ValidationBadId.kt
new file mode 100644
index 0000000..0ae60eb
--- /dev/null
+++ b/ok-marketplace-be/ok-marketplace-biz/src/commonTest/kotlin/validation/ValidationBadId.kt
@@ -0,0 +1,91 @@
+package ru.otus.otuskotlin.marketplace.biz.validation
+
+import kotlinx.coroutines.test.runTest
+import ru.otus.otuskotlin.marketplace.biz.MkplAdProcessor
+import ru.otus.otuskotlin.marketplace.common.MkplContext
+import ru.otus.otuskotlin.marketplace.common.models.*
+import kotlin.test.assertContains
+import kotlin.test.assertEquals
+import kotlin.test.assertNotEquals
+
+fun validationIdCorrect(command: MkplCommand, processor: MkplAdProcessor) = runTest {
+    val ctx = MkplContext(
+        command = command,
+        state = MkplState.NONE,
+        workMode = MkplWorkMode.TEST,
+        adRequest = MkplAd(
+            id = MkplAdId("123-234-abc-ABC"),
+            title = "abc",
+            description = "abc",
+            adType = MkplDealSide.DEMAND,
+            visibility = MkplVisibility.VISIBLE_PUBLIC,
+            lock = MkplAdLock("123-234-abc-ABC"),
+        ),
+    )
+    processor.exec(ctx)
+    assertEquals(0, ctx.errors.size)
+    assertNotEquals(MkplState.FAILING, ctx.state)
+}
+
+fun validationIdTrim(command: MkplCommand, processor: MkplAdProcessor) = runTest {
+    val ctx = MkplContext(
+        command = command,
+        state = MkplState.NONE,
+        workMode = MkplWorkMode.TEST,
+        adRequest = MkplAd(
+            id = MkplAdId(" \n\t 123-234-abc-ABC \n\t "),
+            title = "abc",
+            description = "abc",
+            adType = MkplDealSide.DEMAND,
+            visibility = MkplVisibility.VISIBLE_PUBLIC,
+            lock = MkplAdLock("123-234-abc-ABC"),
+        ),
+    )
+    processor.exec(ctx)
+    assertEquals(0, ctx.errors.size)
+    assertNotEquals(MkplState.FAILING, ctx.state)
+}
+
+fun validationIdEmpty(command: MkplCommand, processor: MkplAdProcessor) = runTest {
+    val ctx = MkplContext(
+        command = command,
+        state = MkplState.NONE,
+        workMode = MkplWorkMode.TEST,
+        adRequest = MkplAd(
+            id = MkplAdId(""),
+            title = "abc",
+            description = "abc",
+            adType = MkplDealSide.DEMAND,
+            visibility = MkplVisibility.VISIBLE_PUBLIC,
+            lock = MkplAdLock("123-234-abc-ABC"),
+        ),
+    )
+    processor.exec(ctx)
+    assertEquals(1, ctx.errors.size)
+    assertEquals(MkplState.FAILING, ctx.state)
+    val error = ctx.errors.firstOrNull()
+    assertEquals("id", error?.field)
+    assertContains(error?.message ?: "", "id")
+}
+
+fun validationIdFormat(command: MkplCommand, processor: MkplAdProcessor) = runTest {
+    val ctx = MkplContext(
+        command = command,
+        state = MkplState.NONE,
+        workMode = MkplWorkMode.TEST,
+        adRequest = MkplAd(
+            id = MkplAdId("!@#\$%^&*(),.{}"),
+            title = "abc",
+            description = "abc",
+            adType = MkplDealSide.DEMAND,
+            visibility = MkplVisibility.VISIBLE_PUBLIC,
+            lock = MkplAdLock("123-234-abc-ABC"),
+        ),
+    )
+    processor.exec(ctx)
+    assertEquals(1, ctx.errors.size)
+    assertEquals(MkplState.FAILING, ctx.state)
+    val error = ctx.errors.firstOrNull()
+    assertEquals("id", error?.field)
+    assertContains(error?.message ?: "", "id")
+}
diff --git a/ok-marketplace-be/ok-marketplace-biz/src/commonTest/kotlin/validation/ValidationBadLock.kt b/ok-marketplace-be/ok-marketplace-biz/src/commonTest/kotlin/validation/ValidationBadLock.kt
new file mode 100644
index 0000000..8619199
--- /dev/null
+++ b/ok-marketplace-be/ok-marketplace-biz/src/commonTest/kotlin/validation/ValidationBadLock.kt
@@ -0,0 +1,91 @@
+package validation
+
+import kotlinx.coroutines.test.runTest
+import ru.otus.otuskotlin.marketplace.biz.MkplAdProcessor
+import ru.otus.otuskotlin.marketplace.common.MkplContext
+import ru.otus.otuskotlin.marketplace.common.models.*
+import kotlin.test.assertContains
+import kotlin.test.assertEquals
+import kotlin.test.assertNotEquals
+
+fun validationLockCorrect(command: MkplCommand, processor: MkplAdProcessor) = runTest {
+    val ctx = MkplContext(
+        command = command,
+        state = MkplState.NONE,
+        workMode = MkplWorkMode.TEST,
+        adRequest = MkplAd(
+            id = MkplAdId("123-234-abc-ABC"),
+            title = "abc",
+            description = "abc",
+            adType = MkplDealSide.DEMAND,
+            visibility = MkplVisibility.VISIBLE_PUBLIC,
+            lock = MkplAdLock("123-234-abc-ABC"),
+        ),
+    )
+    processor.exec(ctx)
+    assertEquals(0, ctx.errors.size)
+    assertNotEquals(MkplState.FAILING, ctx.state)
+}
+
+fun validationLockTrim(command: MkplCommand, processor: MkplAdProcessor) = runTest {
+    val ctx = MkplContext(
+        command = command,
+        state = MkplState.NONE,
+        workMode = MkplWorkMode.TEST,
+        adRequest = MkplAd(
+            id = MkplAdId("123-234-abc-ABC"),
+            title = "abc",
+            description = "abc",
+            adType = MkplDealSide.DEMAND,
+            visibility = MkplVisibility.VISIBLE_PUBLIC,
+            lock = MkplAdLock(" \n\t 123-234-abc-ABC \n\t "),
+        ),
+    )
+    processor.exec(ctx)
+    assertEquals(0, ctx.errors.size)
+    assertNotEquals(MkplState.FAILING, ctx.state)
+}
+
+fun validationLockEmpty(command: MkplCommand, processor: MkplAdProcessor) = runTest {
+    val ctx = MkplContext(
+        command = command,
+        state = MkplState.NONE,
+        workMode = MkplWorkMode.TEST,
+        adRequest = MkplAd(
+            id = MkplAdId("123-234-abc-ABC"),
+            title = "abc",
+            description = "abc",
+            adType = MkplDealSide.DEMAND,
+            visibility = MkplVisibility.VISIBLE_PUBLIC,
+            lock = MkplAdLock(""),
+        ),
+    )
+    processor.exec(ctx)
+    assertEquals(1, ctx.errors.size)
+    assertEquals(MkplState.FAILING, ctx.state)
+    val error = ctx.errors.firstOrNull()
+    assertEquals("lock", error?.field)
+    assertContains(error?.message ?: "", "id")
+}
+
+fun validationLockFormat(command: MkplCommand, processor: MkplAdProcessor) = runTest {
+    val ctx = MkplContext(
+        command = command,
+        state = MkplState.NONE,
+        workMode = MkplWorkMode.TEST,
+        adRequest = MkplAd(
+            id = MkplAdId("123-234-abc-ABC"),
+            title = "abc",
+            description = "abc",
+            adType = MkplDealSide.DEMAND,
+            visibility = MkplVisibility.VISIBLE_PUBLIC,
+            lock = MkplAdLock("!@#\$%^&*(),.{}"),
+        ),
+    )
+    processor.exec(ctx)
+    assertEquals(1, ctx.errors.size)
+    assertEquals(MkplState.FAILING, ctx.state)
+    val error = ctx.errors.firstOrNull()
+    assertEquals("lock", error?.field)
+    assertContains(error?.message ?: "", "id")
+}
diff --git a/ok-marketplace-be/ok-marketplace-biz/src/commonTest/kotlin/validation/ValidationBadTitle.kt b/ok-marketplace-be/ok-marketplace-biz/src/commonTest/kotlin/validation/ValidationBadTitle.kt
new file mode 100644
index 0000000..3bd52c5
--- /dev/null
+++ b/ok-marketplace-be/ok-marketplace-biz/src/commonTest/kotlin/validation/ValidationBadTitle.kt
@@ -0,0 +1,96 @@
+package ru.otus.otuskotlin.marketplace.biz.validation
+
+import kotlinx.coroutines.test.runTest
+import ru.otus.otuskotlin.marketplace.biz.MkplAdProcessor
+import ru.otus.otuskotlin.marketplace.common.MkplContext
+import ru.otus.otuskotlin.marketplace.common.models.*
+import ru.otus.otuskotlin.marketplace.stubs.MkplAdStub
+import kotlin.test.assertContains
+import kotlin.test.assertEquals
+import kotlin.test.assertNotEquals
+
+private val stub = MkplAdStub.get()
+
+fun validationTitleCorrect(command: MkplCommand, processor: MkplAdProcessor) = runTest {
+    val ctx = MkplContext(
+        command = command,
+        state = MkplState.NONE,
+        workMode = MkplWorkMode.TEST,
+        adRequest = MkplAd(
+            id = stub.id,
+            title = "abc",
+            description = "abc",
+            adType = MkplDealSide.DEMAND,
+            visibility = MkplVisibility.VISIBLE_PUBLIC,
+            lock = MkplAdLock("123-234-abc-ABC"),
+        ),
+    )
+    processor.exec(ctx)
+    assertEquals(0, ctx.errors.size)
+    assertNotEquals(MkplState.FAILING, ctx.state)
+    assertEquals("abc", ctx.adValidated.title)
+}
+
+fun validationTitleTrim(command: MkplCommand, processor: MkplAdProcessor) = runTest {
+    val ctx = MkplContext(
+        command = command,
+        state = MkplState.NONE,
+        workMode = MkplWorkMode.TEST,
+        adRequest = MkplAd(
+            id = stub.id,
+            title = " \n\t abc \t\n ",
+            description = "abc",
+            adType = MkplDealSide.DEMAND,
+            visibility = MkplVisibility.VISIBLE_PUBLIC,
+            lock = MkplAdLock("123-234-abc-ABC"),
+        ),
+    )
+    processor.exec(ctx)
+    assertEquals(0, ctx.errors.size)
+    assertNotEquals(MkplState.FAILING, ctx.state)
+    assertEquals("abc", ctx.adValidated.title)
+}
+
+fun validationTitleEmpty(command: MkplCommand, processor: MkplAdProcessor) = runTest {
+    val ctx = MkplContext(
+        command = command,
+        state = MkplState.NONE,
+        workMode = MkplWorkMode.TEST,
+        adRequest = MkplAd(
+            id = stub.id,
+            title = "",
+            description = "abc",
+            adType = MkplDealSide.DEMAND,
+            visibility = MkplVisibility.VISIBLE_PUBLIC,
+            lock = MkplAdLock("123-234-abc-ABC"),
+        ),
+    )
+    processor.exec(ctx)
+    assertEquals(1, ctx.errors.size)
+    assertEquals(MkplState.FAILING, ctx.state)
+    val error = ctx.errors.firstOrNull()
+    assertEquals("title", error?.field)
+    assertContains(error?.message ?: "", "title")
+}
+
+fun validationTitleSymbols(command: MkplCommand, processor: MkplAdProcessor) = runTest {
+    val ctx = MkplContext(
+        command = command,
+        state = MkplState.NONE,
+        workMode = MkplWorkMode.TEST,
+        adRequest = MkplAd(
+            id = MkplAdId("123"),
+            title = "!@#$%^&*(),.{}",
+            description = "abc",
+            adType = MkplDealSide.DEMAND,
+            visibility = MkplVisibility.VISIBLE_PUBLIC,
+            lock = MkplAdLock("123-234-abc-ABC"),
+        ),
+    )
+    processor.exec(ctx)
+    assertEquals(1, ctx.errors.size)
+    assertEquals(MkplState.FAILING, ctx.state)
+    val error = ctx.errors.firstOrNull()
+    assertEquals("title", error?.field)
+    assertContains(error?.message ?: "", "title")
+}
diff --git a/ok-marketplace-be/ok-marketplace-common/src/commonMain/kotlin/MkplContext.kt b/ok-marketplace-be/ok-marketplace-common/src/commonMain/kotlin/MkplContext.kt
index 7ab6829..786f222 100644
--- a/ok-marketplace-be/ok-marketplace-common/src/commonMain/kotlin/MkplContext.kt
+++ b/ok-marketplace-be/ok-marketplace-common/src/commonMain/kotlin/MkplContext.kt
@@ -20,7 +20,12 @@ data class MkplContext(
     var adRequest: MkplAd = MkplAd(),
     var adFilterRequest: MkplAdFilter = MkplAdFilter(),
 
+    var adValidating: MkplAd = MkplAd(),
+    var adFilterValidating: MkplAdFilter = MkplAdFilter(),
+
+    var adValidated: MkplAd = MkplAd(),
+    var adFilterValidated: MkplAdFilter = MkplAdFilter(),
+
     var adResponse: MkplAd = MkplAd(),
     var adsResponse: MutableList<MkplAd> = mutableListOf(),
-
-    )
+)
diff --git a/ok-marketplace-be/ok-marketplace-common/src/commonMain/kotlin/helpers/MkplErrorsHelpers.kt b/ok-marketplace-be/ok-marketplace-common/src/commonMain/kotlin/helpers/MkplErrorsHelpers.kt
index f0e1e84..18878bd 100644
--- a/ok-marketplace-be/ok-marketplace-common/src/commonMain/kotlin/helpers/MkplErrorsHelpers.kt
+++ b/ok-marketplace-be/ok-marketplace-common/src/commonMain/kotlin/helpers/MkplErrorsHelpers.kt
@@ -3,6 +3,7 @@ package ru.otus.otuskotlin.marketplace.common.helpers
 import ru.otus.otuskotlin.marketplace.common.MkplContext
 import ru.otus.otuskotlin.marketplace.common.models.MkplError
 import ru.otus.otuskotlin.marketplace.common.models.MkplState
+import ru.otus.otuskotlin.marketplace.logging.common.LogLevel
 
 fun Throwable.asMkplError(
     code: String = "unknown",
@@ -22,3 +23,20 @@ inline fun MkplContext.fail(error: MkplError) {
     addError(error)
     state = MkplState.FAILING
 }
+
+inline fun errorValidation(
+    field: String,
+    /**
+     * Код, характеризующий ошибку. Не должен включать имя поля или указание на валидацию.
+     * Например: empty, badSymbols, tooLong, etc
+     */
+    violationCode: String,
+    description: String,
+    level: LogLevel = LogLevel.ERROR,
+) = MkplError(
+    code = "validation-$field-$violationCode",
+    field = field,
+    group = "validation",
+    message = "Validation error for field $field: $description",
+    level = level,
+)
diff --git a/ok-marketplace-be/ok-marketplace-common/src/commonMain/kotlin/models/MkplAd.kt b/ok-marketplace-be/ok-marketplace-common/src/commonMain/kotlin/models/MkplAd.kt
index 995fe45..dfd5e36 100644
--- a/ok-marketplace-be/ok-marketplace-common/src/commonMain/kotlin/models/MkplAd.kt
+++ b/ok-marketplace-be/ok-marketplace-common/src/commonMain/kotlin/models/MkplAd.kt
@@ -11,10 +11,13 @@ data class MkplAd(
     var lock: MkplAdLock = MkplAdLock.NONE,
     val permissionsClient: MutableSet<MkplAdPermissionClient> = mutableSetOf()
 ) {
+    fun deepCopy(): MkplAd = copy(
+        permissionsClient = permissionsClient.toMutableSet(),
+    )
+
     fun isEmpty() = this == NONE
 
     companion object {
         private val NONE = MkplAd()
     }
-
 }
diff --git a/ok-marketplace-be/ok-marketplace-common/src/commonMain/kotlin/models/MkplAdFilter.kt b/ok-marketplace-be/ok-marketplace-common/src/commonMain/kotlin/models/MkplAdFilter.kt
index b7352b4..ccb155b 100644
--- a/ok-marketplace-be/ok-marketplace-common/src/commonMain/kotlin/models/MkplAdFilter.kt
+++ b/ok-marketplace-be/ok-marketplace-common/src/commonMain/kotlin/models/MkplAdFilter.kt
@@ -4,4 +4,12 @@ data class MkplAdFilter(
     var searchString: String = "",
     var ownerId: MkplUserId = MkplUserId.NONE,
     var dealSide: MkplDealSide = MkplDealSide.NONE,
-)
+) {
+    fun deepCopy(): MkplAdFilter = copy()
+
+    fun isEmpty() = this == NONE
+
+    companion object {
+        private val NONE = MkplAdFilter()
+    }
+}