From 2cb6e40f23f130c054c18450fae0b811229f7339 Mon Sep 17 00:00:00 2001
From: abdrasulov <abdrasulov@gmail.com>
Date: Mon, 10 Aug 2026 16:47:50 +0600
Subject: [PATCH] Scan full history on initial API restore

A failed first restore attempt leaves block hashes in storage; using
their height as the stop-height cutoff on retry skipped all older
history for keys discovered via gap expansion, permanently losing
their transactions. Apply the cutoff only to incremental re-scans of
a restored wallet, and fail the sync instead of silently dropping
transactions whose block hash cannot be resolved.
---
 .../apisync/blockchair/BlockchairApiSyncer.kt  | 13 +++++++++++--
 .../BlockchairTransactionProvider.kt           | 18 +++++++++++++-----
 2 files changed, 24 insertions(+), 7 deletions(-)

diff --git a/bitcoincore/src/main/kotlin/io/horizontalsystems/bitcoincore/apisync/blockchair/BlockchairApiSyncer.kt b/bitcoincore/src/main/kotlin/io/horizontalsystems/bitcoincore/apisync/blockchair/BlockchairApiSyncer.kt
index d4a3503b8..fa490ff53 100644
--- a/bitcoincore/src/main/kotlin/io/horizontalsystems/bitcoincore/apisync/blockchair/BlockchairApiSyncer.kt
+++ b/bitcoincore/src/main/kotlin/io/horizontalsystems/bitcoincore/apisync/blockchair/BlockchairApiSyncer.kt
@@ -73,7 +73,16 @@ class BlockchairApiSyncer(
     private fun scanSingle(): Single<Unit> = Single.create { emitter ->
         try {
             val allKeys = storage.getPublicKeys()
-            val stopHeight = storage.downloadedTransactionsBestBlockHeight()
+            // A height-based cutoff is only valid for incremental re-scans of a wallet
+            // whose initial restore has completed. During the initial restore the storage
+            // may already hold block hashes from an earlier failed attempt; using their
+            // height as a cutoff would skip all older history for keys discovered later
+            // (gap expansion), permanently losing transactions.
+            val stopHeight = if (apiSyncStateManager.restored) {
+                storage.downloadedTransactionsBestBlockHeight()
+            } else {
+                null
+            }
             fetchRecursive(allKeys, allKeys, stopHeight)
             fetchLastBlock()
 
@@ -88,7 +97,7 @@ class BlockchairApiSyncer(
     private fun fetchRecursive(
         keys: List<PublicKey>,
         allKeys: List<PublicKey>,
-        stopHeight: Int
+        stopHeight: Int?
     ) {
         val publicKeyMap = mutableMapOf<String, PublicKey>()
         val addresses = mutableListOf<String>()
diff --git a/bitcoincore/src/main/kotlin/io/horizontalsystems/bitcoincore/apisync/blockchair/BlockchairTransactionProvider.kt b/bitcoincore/src/main/kotlin/io/horizontalsystems/bitcoincore/apisync/blockchair/BlockchairTransactionProvider.kt
index c0befdd2e..085b19182 100644
--- a/bitcoincore/src/main/kotlin/io/horizontalsystems/bitcoincore/apisync/blockchair/BlockchairTransactionProvider.kt
+++ b/bitcoincore/src/main/kotlin/io/horizontalsystems/bitcoincore/apisync/blockchair/BlockchairTransactionProvider.kt
@@ -2,6 +2,7 @@ package io.horizontalsystems.bitcoincore.apisync.blockchair
 
 import io.horizontalsystems.bitcoincore.apisync.model.TransactionItem
 import io.horizontalsystems.bitcoincore.core.IApiTransactionProvider
+import io.horizontalsystems.bitcoincore.managers.ApiManagerException
 
 class BlockchairTransactionProvider(
     val blockchairApi: BlockchairApi,
@@ -9,11 +10,18 @@ class BlockchairTransactionProvider(
 ) : IApiTransactionProvider {
 
     private fun fillBlockHashes(items: List<TransactionItem>): List<TransactionItem> {
-        val hashesMap = blockHashFetcher.fetch(items.map { it.blockHeight }.distinct())
-        return items.mapNotNull { item ->
-            hashesMap[item.blockHeight]?.let {
-                item.copy(blockHash = it)
-            }
+        val heights = items.map { it.blockHeight }.distinct()
+        val hashesMap = blockHashFetcher.fetch(heights)
+
+        // Every item refers to a confirmed block, so every height must resolve. Failing
+        // the sync keeps it retryable; silently dropping items would lose transactions.
+        val missingHeights = heights.filter { it !in hashesMap }
+        if (missingHeights.isNotEmpty()) {
+            throw ApiManagerException.Other("Missing block hashes for heights: $missingHeights")
+        }
+
+        return items.map { item ->
+            item.copy(blockHash = hashesMap.getValue(item.blockHeight))
         }
     }