fix: decode parent block validation data after runtime upgrade

packages/core/src/blockchain/block.ts

@@ -46,6 +46,7 @@ export class Block {
   #metadata?: Promise<HexString>
   #registry?: Promise<TypeRegistry>
   #meta?: Promise<DecoratedMeta>
+  #extrinsicMeta?: Promise<DecoratedMeta>
 
   #baseStorage: StorageLayerProvider
   #storages: StorageLayer[]
@@ -77,6 +78,7 @@ export class Block {
     this.#metadata = parentBlock?.metadata
     this.#registry = parentBlock?.registry
     this.#meta = parentBlock?.meta
+    this.#extrinsicMeta = parentBlock?.meta
 
     const storageDiff = block?.storageDiff
 
@@ -88,6 +90,9 @@ export class Block {
         this.#metadata = undefined
         this.#registry = undefined
         this.#meta = undefined
+        // #extrinsicMeta intentionally NOT reset: the block's extrinsics were
+        // encoded with the pre-upgrade runtime (parent's metadata), so we
+        // preserve it for correct extrinsic decoding after a runtime upgrade.
       }
 
       this.pushStorageLayer().setAll(storageDiff)
@@ -295,6 +300,24 @@ export class Block {
     return this.#meta
   }
 
+  /**
+   * Get the metadata used to encode this block's extrinsics.
+   *
+   * A block's extrinsics are encoded with the runtime that was active *before*
+   * the block executed (i.e. the parent block's post-execution metadata).
+   * After a runtime upgrade, this differs from {@link meta} which reflects the
+   * new runtime. For blocks without an upgrade the two are identical.
+   */
+  get extrinsicMeta(): Promise<DecoratedMeta> {
+    if (!this.#extrinsicMeta) {
+      this.#extrinsicMeta = (async () => {
+        const parent = await this.parentBlock
+        return parent ? parent.meta : this.meta
+      })()
+    }
+    return this.#extrinsicMeta
+  }
+
   /**
    * Call a runtime method.
    */

packages/core/src/blockchain/inherent/parachain/validation-data.ts

@@ -65,7 +65,6 @@ export type ValidationData = {
 }
 
 const getValidationData = async (parent: Block, fallback = true): Promise<ValidationData> => {
-  const meta = await parent.meta
   if (parent.number === 0) {
     const { trieRootHash, nodes } = await createProof(MOCK_VALIDATION_DATA.relayChainState.trieNodes, [])
     return {
@@ -79,6 +78,9 @@ const getValidationData = async (parent: Block, fallback = true): Promise<Valida
   }
   try {
     const extrinsics = await parent.extrinsics
+    // Use extrinsicMeta because the block's extrinsics were encoded with the
+    // pre-execution runtime, which may differ from parent.meta after a runtime upgrade.
+    const meta = await parent.extrinsicMeta
     const validationDataExtrinsic = extrinsics.find((extrinsic) => {
       const firstArg = meta.registry.createType<GenericExtrinsic>('GenericExtrinsic', extrinsic)?.args?.[0]
       return firstArg && 'validationData' in firstArg