refactor: Delete ChainstateManager::IsSnapshotActive() method

diff --git a/src/interfaces/chain.h b/src/interfaces/chain.h
index 17417218..686da67b 100644
--- a/src/interfaces/chain.h
+++ b/src/interfaces/chain.h
@@ -391,7 +391,9 @@ public:
     //! removed transactions and already added new transactions.
     virtual void requestMempoolTransactions(Notifications& notifications) = 0;
 
-    //! Return true if an assumed-valid chain is in use.
+    //! Return true if an assumed-valid snapshot is in use. Note that this
+    //! returns true even after the snapshot is validated, until the next node
+    //! restart.
     virtual bool hasAssumedValidChain() = 0;
 
     //! Get internal node context. Useful for testing, but not
diff --git a/src/node/chainstate.cpp b/src/node/chainstate.cpp
index bba518d1..a3010898 100644
--- a/src/node/chainstate.cpp
+++ b/src/node/chainstate.cpp
@@ -210,7 +210,6 @@ ChainstateLoadResult LoadChainstate(ChainstateManager& chainman, const CacheSize
         // ChainstateManager::ResetChainstates(), reinitialize them here without
         // duplicating the blockindex work above.
         assert(chainman.GetAll().empty());
-        assert(!chainman.IsSnapshotActive());
         assert(!chainman.IsSnapshotValidated());
 
         chainman.InitializeChainstate(options.mempool);
diff --git a/src/node/interfaces.cpp b/src/node/interfaces.cpp
index dfcf6629..5113f44f 100644
--- a/src/node/interfaces.cpp
+++ b/src/node/interfaces.cpp
@@ -845,7 +845,8 @@ public:
     }
     bool hasAssumedValidChain() override
     {
-        return chainman().IsSnapshotActive();
+        LOCK(::cs_main);
+        return bool{chainman().CurrentChainstate().m_from_snapshot_blockhash};
     }
 
     NodeContext* context() override { return &m_node; }
diff --git a/src/test/validation_chainstate_tests.cpp b/src/test/validation_chainstate_tests.cpp
index b4aeb5b3..e823193a 100644
--- a/src/test/validation_chainstate_tests.cpp
+++ b/src/test/validation_chainstate_tests.cpp
@@ -95,7 +95,7 @@ BOOST_FIXTURE_TEST_CASE(chainstate_update_tip, TestChain100Setup)
         this, NoMalleation, /*reset_chainstate=*/ true));
 
     // Ensure our active chain is the snapshot chainstate.
-    BOOST_CHECK(WITH_LOCK(::cs_main, return chainman.IsSnapshotActive()));
+    BOOST_CHECK(WITH_LOCK(::cs_main, return chainman.CurrentChainstate().m_from_snapshot_blockhash));
 
     curr_tip = get_notify_tip();
 
diff --git a/src/test/validation_chainstatemanager_tests.cpp b/src/test/validation_chainstatemanager_tests.cpp
index 036089c3..5d0bc907 100644
--- a/src/test/validation_chainstatemanager_tests.cpp
+++ b/src/test/validation_chainstatemanager_tests.cpp
@@ -49,7 +49,7 @@ BOOST_FIXTURE_TEST_CASE(chainstatemanager, TestChain100Setup)
     Chainstate& c1 = manager.ActiveChainstate();
     chainstates.push_back(&c1);
 
-    BOOST_CHECK(!manager.IsSnapshotActive());
+    BOOST_CHECK(WITH_LOCK(::cs_main, return !manager.CurrentChainstate().m_from_snapshot_blockhash));
     BOOST_CHECK(WITH_LOCK(::cs_main, return !manager.IsSnapshotValidated()));
     auto all = manager.GetAll();
     BOOST_CHECK_EQUAL_COLLECTIONS(all.begin(), all.end(), chainstates.begin(), chainstates.end());
@@ -84,7 +84,7 @@ BOOST_FIXTURE_TEST_CASE(chainstatemanager, TestChain100Setup)
     BOOST_CHECK(c2.ActivateBestChain(_, nullptr));
 
     BOOST_CHECK_EQUAL(manager.SnapshotBlockhash().value(), snapshot_blockhash);
-    BOOST_CHECK(manager.IsSnapshotActive());
+    BOOST_CHECK(WITH_LOCK(::cs_main, return manager.CurrentChainstate().m_from_snapshot_blockhash));
     BOOST_CHECK(WITH_LOCK(::cs_main, return !manager.IsSnapshotValidated()));
     BOOST_CHECK_EQUAL(&c2, &manager.ActiveChainstate());
     BOOST_CHECK(&c1 != &manager.ActiveChainstate());
@@ -182,10 +182,9 @@ struct SnapshotTestSetup : TestChain100Setup {
     {
         ChainstateManager& chainman = *Assert(m_node.chainman);
 
-        BOOST_CHECK(!chainman.IsSnapshotActive());
-
         {
             LOCK(::cs_main);
+            BOOST_CHECK(!chainman.CurrentChainstate().m_from_snapshot_blockhash);
             BOOST_CHECK(!chainman.IsSnapshotValidated());
             BOOST_CHECK(!node::FindAssumeutxoChainstateDir(chainman.m_options.datadir));
         }
@@ -569,7 +568,7 @@ BOOST_FIXTURE_TEST_CASE(chainstatemanager_snapshot_init, SnapshotTestSetup)
     BOOST_CHECK(fs::exists(snapshot_chainstate_dir));
     BOOST_CHECK_EQUAL(snapshot_chainstate_dir, gArgs.GetDataDirNet() / "chainstate_snapshot");
 
-    BOOST_CHECK(chainman.IsSnapshotActive());
+    BOOST_CHECK(WITH_LOCK(::cs_main, return chainman.CurrentChainstate().m_from_snapshot_blockhash));
     const uint256 snapshot_tip_hash = WITH_LOCK(chainman.GetMutex(),
         return chainman.ActiveTip()->GetBlockHash());
 
@@ -611,7 +610,7 @@ BOOST_FIXTURE_TEST_CASE(chainstatemanager_snapshot_init, SnapshotTestSetup)
         BOOST_CHECK_EQUAL(chainstates[0]->m_chain.Height(), 109);
         BOOST_CHECK_EQUAL(chainstates[1]->m_chain.Height(), 210);
 
-        BOOST_CHECK(chainman_restarted.IsSnapshotActive());
+        BOOST_CHECK(chainman_restarted.CurrentChainstate().m_from_snapshot_blockhash);
         BOOST_CHECK(!chainman_restarted.IsSnapshotValidated());
 
         BOOST_CHECK_EQUAL(chainman_restarted.ActiveTip()->GetBlockHash(), snapshot_tip_hash);
@@ -650,7 +649,7 @@ BOOST_FIXTURE_TEST_CASE(chainstatemanager_snapshot_completion, SnapshotTestSetup
     BOOST_CHECK(fs::exists(snapshot_chainstate_dir));
     BOOST_CHECK_EQUAL(snapshot_chainstate_dir, gArgs.GetDataDirNet() / "chainstate_snapshot");
 
-    BOOST_CHECK(chainman.IsSnapshotActive());
+    BOOST_CHECK(WITH_LOCK(::cs_main, return chainman.CurrentChainstate().m_from_snapshot_blockhash));
     const uint256 snapshot_tip_hash = WITH_LOCK(chainman.GetMutex(),
         return chainman.ActiveTip()->GetBlockHash());
 
@@ -658,7 +657,7 @@ BOOST_FIXTURE_TEST_CASE(chainstatemanager_snapshot_completion, SnapshotTestSetup
     BOOST_CHECK_EQUAL(res, SnapshotCompletionResult::SUCCESS);
 
     WITH_LOCK(::cs_main, BOOST_CHECK(chainman.IsSnapshotValidated()));
-    BOOST_CHECK(chainman.IsSnapshotActive());
+    BOOST_CHECK(WITH_LOCK(::cs_main, return chainman.CurrentChainstate().m_from_snapshot_blockhash));
 
     // Cache should have been rebalanced and reallocated to the "only" remaining
     // chainstate.
@@ -699,7 +698,7 @@ BOOST_FIXTURE_TEST_CASE(chainstatemanager_snapshot_completion, SnapshotTestSetup
     {
         LOCK(chainman_restarted.GetMutex());
         BOOST_CHECK_EQUAL(chainman_restarted.GetAll().size(), 1);
-        BOOST_CHECK(!chainman_restarted.IsSnapshotActive());
+        BOOST_CHECK(!chainman_restarted.CurrentChainstate().m_from_snapshot_blockhash);
         BOOST_CHECK(!chainman_restarted.IsSnapshotValidated());
         BOOST_CHECK(active_cs2.m_coinstip_cache_size_bytes > tip_cache_before_complete);
         BOOST_CHECK(active_cs2.m_coinsdb_cache_size_bytes > db_cache_before_complete);
@@ -771,7 +770,7 @@ BOOST_FIXTURE_TEST_CASE(chainstatemanager_snapshot_completion_hash_mismatch, Sna
     {
         LOCK(::cs_main);
         BOOST_CHECK_EQUAL(chainman_restarted.GetAll().size(), 1);
-        BOOST_CHECK(!chainman_restarted.IsSnapshotActive());
+        BOOST_CHECK(!chainman_restarted.CurrentChainstate().m_from_snapshot_blockhash);
         BOOST_CHECK(!chainman_restarted.IsSnapshotValidated());
         BOOST_CHECK_EQUAL(chainman_restarted.ActiveHeight(), 210);
     }
diff --git a/src/validation.cpp b/src/validation.cpp
index c229851e..ff868911 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -6179,12 +6179,6 @@ Chainstate& ChainstateManager::ActiveChainstate() const
     return *m_active_chainstate;
 }
 
-bool ChainstateManager::IsSnapshotActive() const
-{
-    LOCK(::cs_main);
-    return m_snapshot_chainstate && m_active_chainstate == m_snapshot_chainstate.get();
-}
-
 void ChainstateManager::MaybeRebalanceCaches()
 {
     AssertLockHeld(::cs_main);
diff --git a/src/validation.h b/src/validation.h
index 0f7fa2cb..30d3c2ae 100644
--- a/src/validation.h
+++ b/src/validation.h
@@ -1189,10 +1189,6 @@ public:
      */
     mutable VersionBitsCache m_versionbitscache;
 
-    //! @returns true if a snapshot-based chainstate is in use. Also implies
-    //!          that a background validation chainstate is also in use.
-    bool IsSnapshotActive() const;
-
     std::optional<uint256> SnapshotBlockhash() const;
 
     //! Is there a snapshot in use and has it been fully validated?