rpc, test: Address feedback from #29668

diff --git a/src/rpc/blockchain.cpp b/src/rpc/blockchain.cpp
index a883570f..d7e316dd 100644
--- a/src/rpc/blockchain.cpp
+++ b/src/rpc/blockchain.cpp
@@ -864,7 +864,7 @@ std::optional<int> GetPruneHeight(const BlockManager& blockman, const CChain& ch
     if (!first_block || !chain_tip) return std::nullopt;
 
     // If the chain tip is pruned, everything is pruned.
-    if (!((chain_tip->nStatus & BLOCK_HAVE_MASK) == BLOCK_HAVE_MASK)) return chain_tip->nHeight;
+    if ((chain_tip->nStatus & BLOCK_HAVE_MASK) != BLOCK_HAVE_MASK) return chain_tip->nHeight;
 
     const auto& first_unpruned{blockman.GetFirstBlock(*chain_tip, /*status_mask=*/BLOCK_HAVE_MASK, first_block)};
     if (&first_unpruned == first_block) {
@@ -1354,7 +1354,7 @@ RPCHelpMan getblockchaininfo()
                 {RPCResult::Type::STR_HEX, "chainwork", "total amount of work in active chain, in hexadecimal"},
                 {RPCResult::Type::NUM, "size_on_disk", "the estimated size of the block and undo files on disk"},
                 {RPCResult::Type::BOOL, "pruned", "if the blocks are subject to pruning"},
-                {RPCResult::Type::NUM, "pruneheight", /*optional=*/true, "height of the last block pruned, plus one (only present if pruning is enabled)"},
+                {RPCResult::Type::NUM, "pruneheight", /*optional=*/true, "the first block unpruned, all previous blocks were pruned (only present if pruning is enabled)"},
                 {RPCResult::Type::BOOL, "automatic_pruning", /*optional=*/true, "whether automatic pruning is enabled (only present if pruning is enabled)"},
                 {RPCResult::Type::NUM, "prune_target_size", /*optional=*/true, "the target size used by pruning (only present if automatic pruning is enabled)"},
                 {RPCResult::Type::STR_HEX, "signet_challenge", /*optional=*/true, "the block challenge (aka. block script), in hexadecimal (only present if the current network is a signet)"},
diff --git a/src/rpc/blockchain.h b/src/rpc/blockchain.h
index d14a43b2..efb06ac2 100644
--- a/src/rpc/blockchain.h
+++ b/src/rpc/blockchain.h
@@ -9,15 +9,18 @@
 #include <core_io.h>
 #include <streams.h>
 #include <sync.h>
+#include <threadsafety.h>
 #include <util/fs.h>
 #include <validation.h>
 
 #include <any>
 #include <cstdint>
+#include <optional>
 #include <vector>
 
 class CBlock;
 class CBlockIndex;
+class CChain;
 class Chainstate;
 class UniValue;
 namespace node {
diff --git a/src/test/blockchain_tests.cpp b/src/test/blockchain_tests.cpp
index c6b35e32..c160f4e2 100644
--- a/src/test/blockchain_tests.cpp
+++ b/src/test/blockchain_tests.cpp
@@ -80,7 +80,7 @@ BOOST_AUTO_TEST_CASE(get_difficulty_for_very_high_target)
 
 //! Prune chain from height down to genesis block and check that
 //! GetPruneHeight returns the correct value
-static void CheckGetPruneHeight(node::BlockManager& blockman, CChain& chain, int height) EXCLUSIVE_LOCKS_REQUIRED(::cs_main)
+static void CheckGetPruneHeight(const node::BlockManager& blockman, const CChain& chain, int height) EXCLUSIVE_LOCKS_REQUIRED(::cs_main)
 {
     AssertLockHeld(::cs_main);
 
@@ -98,8 +98,8 @@ static void CheckGetPruneHeight(node::BlockManager& blockman, CChain& chain, int
 BOOST_FIXTURE_TEST_CASE(get_prune_height, TestChain100Setup)
 {
     LOCK(::cs_main);
-    auto& chain = m_node.chainman->ActiveChain();
-    auto& blockman = m_node.chainman->m_blockman;
+    const auto& chain = m_node.chainman->ActiveChain();
+    const auto& blockman = m_node.chainman->m_blockman;
 
     // Fresh chain of 100 blocks without any pruned blocks, so std::nullopt should be returned
     BOOST_CHECK(!GetPruneHeight(blockman, chain).has_value());