feat(tensor): TensorId — structured identity from the module tree, assignTensorIds, describe() renderer (SKEEP-003 P1, S0.5)

skainet-backends/skainet-backend-cpu/api/jvm/skainet-backend-cpu.api

@@ -314,6 +314,7 @@ protected final class sk/ainet/exec/tensor/ops/DefaultCpuOpsBase$CpuTensor : sk/
 	public fun getDtype ()Lkotlin/reflect/KClass;
 	public fun getGrad ()Lsk/ainet/lang/tensor/Tensor;
 	public fun getGradState ()Lsk/ainet/lang/tensor/GradState;
+	public fun getId ()Lsk/ainet/lang/tensor/TensorId;
 	public fun getOps ()Lsk/ainet/lang/tensor/ops/TensorOps;
 	public fun getRank ()I
 	public fun getRequiresGrad ()Z

skainet-lang/skainet-lang-core/api/jvm/skainet-lang-core.api

@@ -665,6 +665,12 @@ public final class sk/ainet/lang/memory/AllocationSpec$Companion {
 	public static synthetic fun of$default (Lsk/ainet/lang/memory/AllocationSpec$Companion;Lsk/ainet/lang/memory/Format;Lsk/ainet/lang/tensor/Shape;Lsk/ainet/lang/tensor/storage/MemoryDomain;Lsk/ainet/lang/memory/ScopeKind;ZIILjava/lang/Object;)Lsk/ainet/lang/memory/AllocationSpec;
 }
 
+public final class sk/ainet/lang/memory/DescribeKt {
+	public static final fun describe (Lsk/ainet/lang/tensor/Tensor;)Ljava/lang/String;
+	public static final fun describe (Lsk/ainet/lang/tensor/storage/TensorStorage;Lsk/ainet/lang/tensor/TensorId;)Ljava/lang/String;
+	public static synthetic fun describe$default (Lsk/ainet/lang/tensor/storage/TensorStorage;Lsk/ainet/lang/tensor/TensorId;ILjava/lang/Object;)Ljava/lang/String;
+}
+
 public abstract interface annotation class sk/ainet/lang/memory/ExperimentalMemoryApi : java/lang/annotation/Annotation {
 }
 
@@ -2368,6 +2374,26 @@ public final class sk/ainet/lang/nn/topology/Parameter {
 	public fun toString ()Ljava/lang/String;
 }
 
+public final class sk/ainet/lang/nn/topology/TensorIdAssignment {
+	public fun <init> (Ljava/util/Map;Ljava/util/List;)V
+	public final fun component1 ()Ljava/util/Map;
+	public final fun component2 ()Ljava/util/List;
+	public final fun copy (Ljava/util/Map;Ljava/util/List;)Lsk/ainet/lang/nn/topology/TensorIdAssignment;
+	public static synthetic fun copy$default (Lsk/ainet/lang/nn/topology/TensorIdAssignment;Ljava/util/Map;Ljava/util/List;ILjava/lang/Object;)Lsk/ainet/lang/nn/topology/TensorIdAssignment;
+	public fun equals (Ljava/lang/Object;)Z
+	public final fun get (Ljava/lang/String;)Lsk/ainet/lang/tensor/Tensor;
+	public final fun get (Lsk/ainet/lang/tensor/TensorId;)Lsk/ainet/lang/tensor/Tensor;
+	public final fun getNotCarried ()Ljava/util/List;
+	public final fun getTensors ()Ljava/util/Map;
+	public fun hashCode ()I
+	public fun toString ()Ljava/lang/String;
+}
+
+public final class sk/ainet/lang/nn/topology/TensorIdsKt {
+	public static final fun assignTensorIds (Lsk/ainet/lang/nn/topology/ModuleNode;Ljava/lang/String;)Lsk/ainet/lang/nn/topology/TensorIdAssignment;
+	public static synthetic fun assignTensorIds$default (Lsk/ainet/lang/nn/topology/ModuleNode;Ljava/lang/String;ILjava/lang/Object;)Lsk/ainet/lang/nn/topology/TensorIdAssignment;
+}
+
 public final class sk/ainet/lang/nn/topology/TraversalKt {
 	public static final fun bindPaths (Lsk/ainet/lang/nn/topology/ModuleNode;Ljava/lang/String;Ljava/lang/String;)V
 	public static synthetic fun bindPaths$default (Lsk/ainet/lang/nn/topology/ModuleNode;Ljava/lang/String;Ljava/lang/String;ILjava/lang/Object;)V
@@ -2699,6 +2725,7 @@ public final class sk/ainet/lang/tensor/SlicedTensorView : sk/ainet/lang/tensor/
 	public fun getDtype ()Lkotlin/reflect/KClass;
 	public fun getGrad ()Lsk/ainet/lang/tensor/Tensor;
 	public fun getGradState ()Lsk/ainet/lang/tensor/GradState;
+	public fun getId ()Lsk/ainet/lang/tensor/TensorId;
 	public fun getIndexMapping ()Lsk/ainet/lang/tensor/IndexMapper;
 	public fun getOps ()Lsk/ainet/lang/tensor/ops/TensorOps;
 	public fun getParentTensor ()Lsk/ainet/lang/tensor/Tensor;
@@ -2726,6 +2753,7 @@ public abstract interface class sk/ainet/lang/tensor/Tensor {
 	public abstract fun getDtype ()Lkotlin/reflect/KClass;
 	public fun getGrad ()Lsk/ainet/lang/tensor/Tensor;
 	public abstract fun getGradState ()Lsk/ainet/lang/tensor/GradState;
+	public fun getId ()Lsk/ainet/lang/tensor/TensorId;
 	public abstract fun getOps ()Lsk/ainet/lang/tensor/ops/TensorOps;
 	public fun getRank ()I
 	public fun getRequiresGrad ()Z
@@ -2737,6 +2765,7 @@ public abstract interface class sk/ainet/lang/tensor/Tensor {
 public final class sk/ainet/lang/tensor/Tensor$DefaultImpls {
 	public static fun accumulateGrad (Lsk/ainet/lang/tensor/Tensor;Lsk/ainet/lang/tensor/Tensor;)V
 	public static fun getGrad (Lsk/ainet/lang/tensor/Tensor;)Lsk/ainet/lang/tensor/Tensor;
+	public static fun getId (Lsk/ainet/lang/tensor/Tensor;)Lsk/ainet/lang/tensor/TensorId;
 	public static fun getRank (Lsk/ainet/lang/tensor/Tensor;)I
 	public static fun getRequiresGrad (Lsk/ainet/lang/tensor/Tensor;)Z
 	public static fun getShape (Lsk/ainet/lang/tensor/Tensor;)Lsk/ainet/lang/tensor/Shape;
@@ -2827,6 +2856,34 @@ public abstract interface class sk/ainet/lang/tensor/TensorFactory {
 	public abstract fun zeros (Lsk/ainet/lang/tensor/Shape;)Lsk/ainet/lang/tensor/Tensor;
 }
 
+public final class sk/ainet/lang/tensor/TensorId {
+	public static final field Companion Lsk/ainet/lang/tensor/TensorId$Companion;
+	public fun <init> (Ljava/util/List;Ljava/lang/String;Ljava/lang/String;)V
+	public synthetic fun <init> (Ljava/util/List;Ljava/lang/String;Ljava/lang/String;ILkotlin/jvm/internal/DefaultConstructorMarker;)V
+	public fun equals (Ljava/lang/Object;)Z
+	public final fun getCanonical ()Ljava/lang/String;
+	public final fun getDiscriminator ()Ljava/lang/String;
+	public final fun getModulePath ()Ljava/util/List;
+	public final fun getParameter ()Ljava/lang/String;
+	public fun hashCode ()I
+	public final fun legacyPath (Ljava/lang/String;)Ljava/lang/String;
+	public static synthetic fun legacyPath$default (Lsk/ainet/lang/tensor/TensorId;Ljava/lang/String;ILjava/lang/Object;)Ljava/lang/String;
+	public fun toString ()Ljava/lang/String;
+	public final fun view (Ljava/lang/String;)Lsk/ainet/lang/tensor/TensorId;
+	public final fun withDiscriminator (Ljava/lang/String;)Lsk/ainet/lang/tensor/TensorId;
+}
+
+public final class sk/ainet/lang/tensor/TensorId$Companion {
+	public final fun fromLegacyPath (Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;)Lsk/ainet/lang/tensor/TensorId;
+	public static synthetic fun fromLegacyPath$default (Lsk/ainet/lang/tensor/TensorId$Companion;Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;ILjava/lang/Object;)Lsk/ainet/lang/tensor/TensorId;
+	public final fun parse (Ljava/lang/String;)Lsk/ainet/lang/tensor/TensorId;
+}
+
+public abstract interface class sk/ainet/lang/tensor/TensorIdBearer {
+	public abstract fun getId ()Lsk/ainet/lang/tensor/TensorId;
+	public abstract fun setId (Lsk/ainet/lang/tensor/TensorId;)V
+}
+
 public final class sk/ainet/lang/tensor/TensorSliceBuilder {
 	public fun <init> ()V
 	public final fun segment (Lkotlin/jvm/functions/Function1;)V
@@ -2853,6 +2910,7 @@ public abstract interface class sk/ainet/lang/tensor/TensorView : sk/ainet/lang/
 public final class sk/ainet/lang/tensor/TensorView$DefaultImpls {
 	public static fun accumulateGrad (Lsk/ainet/lang/tensor/TensorView;Lsk/ainet/lang/tensor/Tensor;)V
 	public static fun getGrad (Lsk/ainet/lang/tensor/TensorView;)Lsk/ainet/lang/tensor/Tensor;
+	public static fun getId (Lsk/ainet/lang/tensor/TensorView;)Lsk/ainet/lang/tensor/TensorId;
 	public static fun getRank (Lsk/ainet/lang/tensor/TensorView;)I
 	public static fun getRequiresGrad (Lsk/ainet/lang/tensor/TensorView;)Z
 	public static fun getShape (Lsk/ainet/lang/tensor/TensorView;)Lsk/ainet/lang/tensor/Shape;
@@ -2909,19 +2967,21 @@ public final class sk/ainet/lang/tensor/ViewManagementExtensionsKt {
 	public static final fun isContiguous (Lsk/ainet/lang/tensor/TensorView;)Z
 }
 
-public final class sk/ainet/lang/tensor/VoidOpsTensor : sk/ainet/lang/tensor/Tensor {
+public final class sk/ainet/lang/tensor/VoidOpsTensor : sk/ainet/lang/tensor/Tensor, sk/ainet/lang/tensor/TensorIdBearer {
 	public fun <init> (Lsk/ainet/lang/tensor/data/TensorData;Lkotlin/reflect/KClass;Lsk/ainet/lang/tensor/GradState;)V
 	public synthetic fun <init> (Lsk/ainet/lang/tensor/data/TensorData;Lkotlin/reflect/KClass;Lsk/ainet/lang/tensor/GradState;ILkotlin/jvm/internal/DefaultConstructorMarker;)V
 	public fun accumulateGrad (Lsk/ainet/lang/tensor/Tensor;)V
 	public fun getData ()Lsk/ainet/lang/tensor/data/TensorData;
 	public fun getDtype ()Lkotlin/reflect/KClass;
 	public fun getGrad ()Lsk/ainet/lang/tensor/Tensor;
 	public fun getGradState ()Lsk/ainet/lang/tensor/GradState;
+	public fun getId ()Lsk/ainet/lang/tensor/TensorId;
 	public fun getOps ()Lsk/ainet/lang/tensor/ops/TensorOps;
 	public fun getRank ()I
 	public fun getRequiresGrad ()Z
 	public fun getShape ()Lsk/ainet/lang/tensor/Shape;
 	public fun getVolume ()I
+	public fun setId (Lsk/ainet/lang/tensor/TensorId;)V
 	public fun zeroGrad ()V
 }
 
@@ -4123,20 +4183,22 @@ public final class sk/ainet/lang/tensor/operators/OperatorsKt {
 	public static final fun withOps (Lsk/ainet/lang/tensor/Tensor;Lsk/ainet/lang/tensor/ops/TensorOps;)Lsk/ainet/lang/tensor/Tensor;
 }
 
-public final class sk/ainet/lang/tensor/operators/OpsBoundTensor : sk/ainet/lang/tensor/Tensor {
+public final class sk/ainet/lang/tensor/operators/OpsBoundTensor : sk/ainet/lang/tensor/Tensor, sk/ainet/lang/tensor/TensorIdBearer {
 	public static final field Companion Lsk/ainet/lang/tensor/operators/OpsBoundTensor$Companion;
 	public fun <init> (Lsk/ainet/lang/tensor/Tensor;Lsk/ainet/lang/tensor/ops/TensorOps;)V
 	public fun accumulateGrad (Lsk/ainet/lang/tensor/Tensor;)V
 	public fun getData ()Lsk/ainet/lang/tensor/data/TensorData;
 	public fun getDtype ()Lkotlin/reflect/KClass;
 	public fun getGrad ()Lsk/ainet/lang/tensor/Tensor;
 	public fun getGradState ()Lsk/ainet/lang/tensor/GradState;
+	public fun getId ()Lsk/ainet/lang/tensor/TensorId;
 	public fun getOps ()Lsk/ainet/lang/tensor/ops/TensorOps;
 	public final fun getOrigin ()Lsk/ainet/lang/tensor/Tensor;
 	public fun getRank ()I
 	public fun getRequiresGrad ()Z
 	public fun getShape ()Lsk/ainet/lang/tensor/Shape;
 	public fun getVolume ()I
+	public fun setId (Lsk/ainet/lang/tensor/TensorId;)V
 	public fun zeroGrad ()V
 }
 

skainet-lang/skainet-lang-core/src/commonMain/kotlin/sk/ainet/lang/memory/Describe.kt

@@ -0,0 +1,52 @@
+package sk.ainet.lang.memory
+
+import sk.ainet.lang.tensor.Tensor
+import sk.ainet.lang.tensor.storage.BufferHandle
+import sk.ainet.lang.tensor.storage.TensorStorage
+
+/**
+ * One-line debugger rendering of a tensor (SKEEP-003 §4.7, PRD M0-F5):
+ * `TensorId · Format · Shape · storage kind · origin · scope · StorageId`.
+ * Fields that only exist from milestone M1 on (scope, storage id) print as `—`.
+ *
+ * Example: `model.layers.blk.3.attn.q_proj.weight · Float32/Q4_K · [2048, 2048] · Q4_KBlockTensorData · — · scope — · storage —`
+ */
+@ExperimentalMemoryApi
+public fun Tensor<*, *>.describe(): String = buildString {
+    append(id?.canonical ?: "—"); append(SEP)
+    append(formatOrNull?.toString() ?: "?"); append(SEP)
+    append(shapeText(data.shape.dimensions)); append(SEP)
+    append(data::class.simpleName ?: "data"); append(SEP)
+    append("—"); append(SEP)          // origin (file/offset) — storage-backed tensors only, M1
+    append("scope —"); append(SEP)
+    append("storage —")
+}
+
+/** Same rendering for a storage descriptor; origin is the file for file-backed buffers. */
+@ExperimentalMemoryApi
+public fun TensorStorage.describe(id: sk.ainet.lang.tensor.TensorId? = null): String = buildString {
+    append(id?.canonical ?: "—"); append(SEP)
+    append(format.toString()); append(SEP)
+    append(shapeText(shape.dimensions)); append(SEP)
+    append(
+        when (val b = buffer) {
+            is BufferHandle.Owned -> "Owned"
+            is BufferHandle.Borrowed -> "Borrowed"
+            is BufferHandle.Aliased -> "Aliased"
+            is BufferHandle.FileBacked -> "Mapped"
+            is BufferHandle.DeviceResident -> "Device(${b.deviceId})"
+        }
+    ); append(SEP)
+    append(
+        when (val b = buffer) {
+            is BufferHandle.FileBacked -> "${b.path} @0x${b.fileOffset.toString(16)}"
+            else -> "—"
+        }
+    ); append(SEP)
+    append("scope —"); append(SEP)
+    append("storage —")
+}
+
+private const val SEP = " · "
+
+private fun shapeText(dims: IntArray): String = dims.joinToString(", ", "[", "]")

skainet-lang/skainet-lang-core/src/commonMain/kotlin/sk/ainet/lang/nn/topology/TensorIds.kt

@@ -0,0 +1,61 @@
+package sk.ainet.lang.nn.topology
+
+import sk.ainet.lang.tensor.Tensor
+import sk.ainet.lang.tensor.TensorId
+import sk.ainet.lang.tensor.TensorIdBearer
+
+/**
+ * Result of [assignTensorIds]: every parameter tensor of the tree keyed by its [TensorId], and the
+ * ids whose tensor could not carry the id (not a [TensorIdBearer]) — they are still in [tensors].
+ */
+public data class TensorIdAssignment(
+    val tensors: Map<TensorId, Tensor<*, *>>,
+    val notCarried: List<TensorId>,
+) {
+    public operator fun get(id: TensorId): Tensor<*, *>? = tensors[id]
+    public operator fun get(canonical: String): Tensor<*, *>? = tensors[TensorId.parse(canonical)]
+}
+
+/**
+ * Assign a [TensorId] to every parameter tensor in this module tree, derived from the module
+ * structure: the id's module path is the chain of module names from [root] down (the same segments
+ * [bindPaths] uses, so `id.legacyPath()` equals the node's `path`), and its parameter is the
+ * parameter's short name (`weight` for a parameter registered as `"<module>.weight"`).
+ *
+ * Idempotent — running it twice yields the same ids — and free of side effects on tensors that
+ * cannot carry an id (reported in [TensorIdAssignment.notCarried]). No runtime code path changes:
+ * an id is metadata on the parameter tensor.
+ *
+ * ```
+ * val ids = model.assignTensorIds("model")
+ * ids["model.layers.blk.0.attn.weight"]   // the tensor
+ * ```
+ */
+public fun ModuleNode.assignTensorIds(root: String = name): TensorIdAssignment {
+    val tensors = LinkedHashMap<TensorId, Tensor<*, *>>()
+    val notCarried = ArrayList<TensorId>()
+    fun visit(node: ModuleNode, segments: List<String>) {
+        for (p in node.params) {
+            val id = TensorId(segments, parameterShortName(node, p.name))
+            val t = p.value
+            tensors[id] = t
+            if (t is TensorIdBearer) t.id = id else notCarried += id
+        }
+        for (child in node.children) {
+            val seg = child.name.ifEmpty { child.id }
+            visit(child, if (seg.isEmpty()) segments else segments + seg)
+        }
+    }
+    visit(this, if (root.isEmpty()) emptyList() else listOf(root))
+    return TensorIdAssignment(tensors, notCarried)
+}
+
+/** `"<moduleName>.weight"` → `weight`; a name without the module prefix is returned unchanged. */
+internal fun parameterShortName(node: ModuleNode, parameterName: String): String {
+    val prefix = node.name + "."
+    return when {
+        node.name.isNotEmpty() && parameterName.startsWith(prefix) && parameterName.length > prefix.length ->
+            parameterName.substring(prefix.length)
+        else -> parameterName
+    }
+}

skainet-lang/skainet-lang-core/src/commonMain/kotlin/sk/ainet/lang/tensor/Tensor.kt

@@ -81,6 +81,13 @@ public interface Tensor<T : DType, V> {
      */
     public val dtype: KClass<T>
 
+    /**
+     * Stable identity of this tensor within its model (`model.layers[3].attn.q_proj.weight`), or
+     * `null` for an anonymous tensor. Assigned from the module tree by `assignTensorIds`; carried by
+     * implementations of [TensorIdBearer]. Default `null` so existing implementations are unaffected.
+     */
+    public val id: TensorId? get() = null
+
     /**
      * Gradient state tied to this tensor instance.
      */

skainet-lang/skainet-lang-core/src/commonMain/kotlin/sk/ainet/lang/tensor/TensorId.kt

@@ -0,0 +1,88 @@
+package sk.ainet.lang.tensor
+
+/**
+ * Stable, human-readable identity of a tensor derived from the model structure (SKEEP-003 §4.7):
+ * the module path inside the `network { }` / `dag { }` tree, the parameter name, and an optional
+ * discriminator for activations (`#step=17`). The *same* id names the tensor whether it is
+ * materialized or symbolic, eager or compiled, and is what loaders' `NameMap`s, graph nodes
+ * (`loc("…")`) and memory-debugging tools key on.
+ *
+ * Ids are optional — an anonymous `a matMul b` in a notebook has none.
+ *
+ * Two string forms:
+ * - [canonical] — dotted, for logs, `loc()` attributes and greps: `model.layers[3].attn.q_proj.weight`;
+ * - [legacyPath] — the slash-separated module path used by `ModuleNode.path` / `bindPaths` and the
+ *   `WeightNameResolver`s (`MLP/blk.0/attn`), so existing name-based loaders keep working.
+ *
+ * [parse] inverts [canonical] segment-wise; module names that themselves contain `.` (e.g. `blk.0`)
+ * round-trip as a string but split into more segments than they were built from. For that reason
+ * **equality and hashing are defined on [canonical]**: two ids that print the same are the same id,
+ * however they were built (`TensorId.parse(id.canonical) == id` always holds).
+ *
+ * @property modulePath module names from the root down to the owner of the parameter
+ * @property parameter the parameter's short name within its module (`weight`, `bias`, `weight_ih`)
+ * @property discriminator optional suffix for activations / repeated instances
+ */
+public class TensorId(
+    public val modulePath: List<String>,
+    public val parameter: String,
+    public val discriminator: String? = null,
+) {
+    init {
+        require(parameter.isNotEmpty()) { "TensorId.parameter must not be empty" }
+        require(modulePath.none { it.isEmpty() }) { "TensorId.modulePath segments must not be empty: $modulePath" }
+    }
+
+    /** `model.layers[3].attn.q_proj.weight` (+ `#discriminator`). */
+    public val canonical: String
+        get() = buildString {
+            for (s in modulePath) { append(s); append('.') }
+            append(parameter)
+            if (discriminator != null) { append('#'); append(discriminator) }
+        }
+
+    /** The slash-separated module path (`MLP/blk.0/attn`), empty string for a root-level parameter. */
+    public fun legacyPath(separator: String = "/"): String = modulePath.joinToString(separator)
+
+    /** The same id with a different [discriminator] (e.g. `withDiscriminator("step=17")`). */
+    public fun withDiscriminator(discriminator: String?): TensorId = TensorId(modulePath, parameter, discriminator)
+
+    /** Id of a sub-view of this tensor, e.g. `kv.layers[3].k` → `kv.layers[3].k[1024..2048]`. */
+    public fun view(range: String): TensorId = TensorId(modulePath, "$parameter[$range]", discriminator)
+
+    override fun toString(): String = canonical
+
+    /** Equal iff the canonical strings are equal (see the class note). */
+    override fun equals(other: Any?): Boolean = other is TensorId && other.canonical == canonical
+
+    override fun hashCode(): Int = canonical.hashCode()
+
+    public companion object {
+        /**
+         * Parse a [canonical] string: the last dotted segment is the parameter, the preceding
+         * segments the module path, an optional `#…` suffix the discriminator.
+         * @throws IllegalArgumentException for an empty or malformed string
+         */
+        public fun parse(canonical: String): TensorId {
+            require(canonical.isNotBlank()) { "TensorId must not be blank" }
+            val hash = canonical.indexOf('#')
+            val body = if (hash >= 0) canonical.substring(0, hash) else canonical
+            val disc = if (hash >= 0) canonical.substring(hash + 1).ifEmpty { null } else null
+            val segments = body.split('.')
+            require(segments.all { it.isNotEmpty() }) { "Malformed TensorId '$canonical'" }
+            return TensorId(segments.dropLast(1), segments.last(), disc)
+        }
+
+        /** Build from a slash-separated module path (as produced by `bindPaths`) and a parameter name. */
+        public fun fromLegacyPath(path: String?, parameter: String, separator: String = "/"): TensorId =
+            TensorId(path?.takeIf { it.isNotEmpty() }?.split(separator) ?: emptyList(), parameter)
+    }
+}
+
+/**
+ * A tensor that can carry a [TensorId]. The core tensor implementations implement it; `assignTensorIds`
+ * sets ids through this interface and reports tensors that cannot carry one.
+ */
+public interface TensorIdBearer {
+    public var id: TensorId?
+}

skainet-lang/skainet-lang-core/src/commonMain/kotlin/sk/ainet/lang/tensor/VoidOpsTensor.kt

@@ -13,7 +13,9 @@ public class VoidOpsTensor<T : DType, V>(
     override val data: TensorData<T, V>,
     override val dtype: KClass<T>,
     override val gradState: GradState<T, V> = GradState()
-) : Tensor<T, V> {
+) : Tensor<T, V>, TensorIdBearer {
     override val ops: TensorOps
         get() = VoidTensorOps()
+
+    override var id: TensorId? = null
 }