fix: check index sync status before querying and show sync progress

Check sync status upfront for address, timestamp, and spent index RPCs.
Include current sync height in error messages to help users understand
progress, following the pattern used by coinstatsindex.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: UdjinM6

src/rpc/blockchain.cpp

@@ -556,12 +556,17 @@ static RPCHelpMan getblockhashes()
         throw JSONRPCError(RPC_MISC_ERROR, "Timestamp index is not enabled. Start with -timestampindex to enable.");
     }
 
+    const IndexSummary summary = g_timestampindex->GetSummary();
+    if (!summary.synced) {
+        throw JSONRPCError(RPC_MISC_ERROR, strprintf("Timestamp index is syncing. Current height: %d", summary.best_block_height));
+    }
+
     unsigned int high = request.params[0].getInt<int>();
     unsigned int low = request.params[1].getInt<int>();
     std::vector<uint256> blockHashes;
 
     if (!g_timestampindex->GetBlockHashes(high, low, blockHashes)) {
-        throw JSONRPCError(RPC_MISC_ERROR, "Timestamp index is still syncing. Try again later.");
+        throw JSONRPCError(RPC_MISC_ERROR, "Failed to read timestamp index.");
     }
 
     UniValue result(UniValue::VARR);

src/rpc/node.cpp

@@ -500,6 +500,11 @@ static RPCHelpMan getaddressutxos()
         throw JSONRPCError(RPC_MISC_ERROR, "Address index is not enabled. Start with -addressindex to enable.");
     }
 
+    const IndexSummary summary = g_addressindex->GetSummary();
+    if (!summary.synced) {
+        throw JSONRPCError(RPC_MISC_ERROR, strprintf("Address index is syncing. Current height: %d", summary.best_block_height));
+    }
+
     std::vector<CAddressUnspentIndexEntry> unspentOutputs;
 
     for (const auto& address : addresses) {
@@ -587,6 +592,12 @@ static RPCHelpMan getaddressdeltas()
     if (!g_addressindex) {
         throw JSONRPCError(RPC_MISC_ERROR, "Address index is not enabled. Start with -addressindex to enable.");
     }
+
+    const IndexSummary summary = g_addressindex->GetSummary();
+    if (!summary.synced) {
+        throw JSONRPCError(RPC_MISC_ERROR, strprintf("Address index is syncing. Current height: %d", summary.best_block_height));
+    }
+
     for (const auto& address : addresses) {
         if (start <= 0 || end <= 0) { start = 0; end = 0; }
         if (!g_addressindex->GetAddressIndex(address.first, address.second,
@@ -654,21 +665,22 @@ static RPCHelpMan getaddressbalance()
     if (!g_addressindex) {
         throw JSONRPCError(RPC_MISC_ERROR, "Address index is not enabled. Start with -addressindex to enable.");
     }
+
+    // Check sync status first to return a clear error message
+    // Use the index's best block height instead of chain tip to avoid inconsistency
+    const IndexSummary summary = g_addressindex->GetSummary();
+    if (!summary.synced) {
+        throw JSONRPCError(RPC_MISC_ERROR, strprintf("Address index is syncing. Current height: %d", summary.best_block_height));
+    }
+    int nHeight = summary.best_block_height;
+
     for (const auto& address : addresses) {
         if (!g_addressindex->GetAddressIndex(address.first, address.second, addressIndex,
                                              /*start=*/0, /*end=*/0)) {
             throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "No information available for address");
         }
     }
 
-    // Use the index's best block height instead of chain tip to avoid inconsistency
-    // The async index may be behind the chain tip during sync
-    IndexSummary summary = g_addressindex->GetSummary();
-    if (!summary.synced) {
-        throw JSONRPCError(RPC_INTERNAL_ERROR, "Address index not yet synced");
-    }
-    int nHeight = summary.best_block_height;
-
 
     CAmount balance = 0;
     CAmount balance_spendable = 0;
@@ -742,6 +754,12 @@ static RPCHelpMan getaddresstxids()
     if (!g_addressindex) {
         throw JSONRPCError(RPC_MISC_ERROR, "Address index is not enabled. Start with -addressindex to enable.");
     }
+
+    const IndexSummary summary = g_addressindex->GetSummary();
+    if (!summary.synced) {
+        throw JSONRPCError(RPC_MISC_ERROR, strprintf("Address index is syncing. Current height: %d", summary.best_block_height));
+    }
+
     for (const auto& address : addresses) {
         if (start <= 0 || end <= 0) { start = 0; end = 0; }
         if (!g_addressindex->GetAddressIndex(address.first, address.second,
@@ -820,6 +838,11 @@ static RPCHelpMan getspentinfo()
         throw JSONRPCError(RPC_MISC_ERROR, "Spent index is not enabled. Start with -spentindex to enable.");
     }
 
+    const IndexSummary summary = g_spentindex->GetSummary();
+    if (!summary.synced) {
+        throw JSONRPCError(RPC_MISC_ERROR, strprintf("Spent index is syncing. Current height: %d", summary.best_block_height));
+    }
+
     CSpentIndexKey key(txid, outputIndex);
     CSpentIndexValue value;
     bool found = false;