refactor: Add ChainstateManager::CurrentChainstate() method

diff --git a/src/net_processing.cpp b/src/net_processing.cpp
index 6e60ce82..09b2f221 100644
--- a/src/net_processing.cpp
+++ b/src/net_processing.cpp
@@ -1387,7 +1387,7 @@ void PeerManagerImpl::FindNextBlocksToDownload(const Peer& peer, unsigned int co
     // When we sync with AssumeUtxo and discover the snapshot is not in the peer's best chain, abort:
     // We can't reorg to this chain due to missing undo data until the background sync has finished,
     // so downloading blocks from it would be futile.
-    const CBlockIndex* snap_base{m_chainman.GetSnapshotBaseBlock()};
+    const CBlockIndex* snap_base{m_chainman.CurrentChainstate().SnapshotBase()};
     if (snap_base && state->pindexBestKnownBlock->GetAncestor(snap_base->nHeight) != snap_base) {
         LogDebug(BCLog::NET, "Not downloading blocks from peer=%d, which doesn't have the snapshot block in its best chain.\n", peer.m_id);
         return;
diff --git a/src/rpc/blockchain.cpp b/src/rpc/blockchain.cpp
index 8f283ff4..78dbafec 100644
--- a/src/rpc/blockchain.cpp
+++ b/src/rpc/blockchain.cpp
@@ -3432,7 +3432,7 @@ return RPCHelpMan{
 
     ChainstateManager& chainman = EnsureAnyChainman(request.context);
 
-    auto make_chain_data = [&](const Chainstate& cs, bool validated) EXCLUSIVE_LOCKS_REQUIRED(::cs_main) {
+    auto make_chain_data = [&](const Chainstate& cs) EXCLUSIVE_LOCKS_REQUIRED(::cs_main) {
         AssertLockHeld(::cs_main);
         UniValue data(UniValue::VOBJ);
         if (!cs.m_chain.Tip()) {
@@ -3452,17 +3452,16 @@ return RPCHelpMan{
         if (cs.m_from_snapshot_blockhash) {
             data.pushKV("snapshot_blockhash", cs.m_from_snapshot_blockhash->ToString());
         }
-        data.pushKV("validated", validated);
+        data.pushKV("validated", cs.m_assumeutxo == Assumeutxo::VALIDATED);
         return data;
     };
 
     obj.pushKV("headers", chainman.m_best_header ? chainman.m_best_header->nHeight : -1);
-
-    const auto& chainstates = chainman.GetAll();
     UniValue obj_chainstates{UniValue::VARR};
-    for (Chainstate* cs : chainstates) {
-      obj_chainstates.push_back(make_chain_data(*cs, !cs->m_from_snapshot_blockhash || chainstates.size() == 1));
+    if (const Chainstate * cs{chainman.HistoricalChainstate()}) {
+        obj_chainstates.push_back(make_chain_data(*cs));
     }
+    obj_chainstates.push_back(make_chain_data(chainman.CurrentChainstate()));
     obj.pushKV("chainstates", std::move(obj_chainstates));
     return obj;
 }
diff --git a/src/validation.cpp b/src/validation.cpp
index a9bf12b5..fabff80c 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -3841,7 +3841,7 @@ void ChainstateManager::ReceivedBlockTransactions(const CBlock& block, CBlockInd
     // m_chain_tx_count value is not zero, assert that value is actually correct.
     auto prev_tx_sum = [](CBlockIndex& block) { return block.nTx + (block.pprev ? block.pprev->m_chain_tx_count : 0); };
     if (!Assume(pindexNew->m_chain_tx_count == 0 || pindexNew->m_chain_tx_count == prev_tx_sum(*pindexNew) ||
-                pindexNew == GetSnapshotBaseBlock())) {
+                pindexNew == CurrentChainstate().SnapshotBase())) {
         LogWarning("Internal bug detected: block %d has unexpected m_chain_tx_count %i that should be %i (%s %s). Please report this issue here: %s\n",
             pindexNew->nHeight, pindexNew->m_chain_tx_count, prev_tx_sum(*pindexNew), CLIENT_NAME, FormatFullVersion(), CLIENT_BUGREPORT);
         pindexNew->m_chain_tx_count = 0;
@@ -4974,7 +4974,7 @@ bool ChainstateManager::LoadBlockIndex()
             // VALID_TRANSACTIONS (eg if we haven't yet downloaded the block),
             // so we special-case the snapshot block as a potential candidate
             // here.
-            if (pindex == GetSnapshotBaseBlock() ||
+            if (pindex == CurrentChainstate().SnapshotBase() ||
                     (pindex->IsValid(BLOCK_VALID_TRANSACTIONS) &&
                      (pindex->HaveNumChainTxs() || pindex->pprev == nullptr))) {
 
@@ -5263,7 +5263,7 @@ void ChainstateManager::CheckBlockIndex() const
     // to earlier blocks that have not been downloaded or validated yet, so
     // checks for later blocks can assume the earlier blocks were validated and
     // be stricter, testing for more requirements.
-    const CBlockIndex* snap_base{GetSnapshotBaseBlock()};
+    const CBlockIndex* snap_base{CurrentChainstate().SnapshotBase()};
     const CBlockIndex *snap_first_missing{}, *snap_first_notx{}, *snap_first_notv{}, *snap_first_nocv{}, *snap_first_nosv{};
     auto snap_update_firsts = [&] {
         if (pindex == snap_base) {
@@ -6357,11 +6357,6 @@ ChainstateRole Chainstate::GetRole() const
     return m_target_blockhash ? ChainstateRole::BACKGROUND : m_assumeutxo == Assumeutxo::UNVALIDATED ? ChainstateRole::ASSUMEDVALID : ChainstateRole::NORMAL;
 }
 
-const CBlockIndex* ChainstateManager::GetSnapshotBaseBlock() const
-{
-    return m_active_chainstate ? m_active_chainstate->SnapshotBase() : nullptr;
-}
-
 void ChainstateManager::RecalculateBestHeader()
 {
     AssertLockHeld(cs_main);
diff --git a/src/validation.h b/src/validation.h
index 37c6051e..cafe2493 100644
--- a/src/validation.h
+++ b/src/validation.h
@@ -1140,8 +1140,11 @@ public:
     //! if it does happen, it is a fatal error.
     SnapshotCompletionResult MaybeValidateSnapshot(Chainstate& validated_cs, Chainstate& unvalidated_cs) EXCLUSIVE_LOCKS_REQUIRED(::cs_main);
 
-    //! Returns nullptr if no snapshot has been loaded.
-    const CBlockIndex* GetSnapshotBaseBlock() const EXCLUSIVE_LOCKS_REQUIRED(::cs_main);
+    //! Return current chainstate targeting the most-work, network tip.
+    Chainstate& CurrentChainstate() const EXCLUSIVE_LOCKS_REQUIRED(GetMutex())
+    {
+        return *Assert(m_active_chainstate);
+    }
 
     //! Return historical chainstate targeting a specific block, if any.
     Chainstate* HistoricalChainstate() const EXCLUSIVE_LOCKS_REQUIRED(GetMutex())
@@ -1150,11 +1153,16 @@ public:
         return cs && cs->m_target_blockhash && !cs->m_target_utxohash ? cs : nullptr;
     }
 
-    //! The most-work chain.
+    //! Alternatives to CurrentChainstate() used by older code to query latest
+    //! chainstate information without locking cs_main. Newer code should avoid
+    //! querying ChainstateManager and use Chainstate objects directly, or
+    //! should use CurrentChainstate() instead.
+    //! @{
     Chainstate& ActiveChainstate() const;
     CChain& ActiveChain() const EXCLUSIVE_LOCKS_REQUIRED(GetMutex()) { return ActiveChainstate().m_chain; }
     int ActiveHeight() const EXCLUSIVE_LOCKS_REQUIRED(GetMutex()) { return ActiveChain().Height(); }
     CBlockIndex* ActiveTip() const EXCLUSIVE_LOCKS_REQUIRED(GetMutex()) { return ActiveChain().Tip(); }
+    //! @}
 
     node::BlockMap& BlockIndex() EXCLUSIVE_LOCKS_REQUIRED(::cs_main)
     {