fix: initialize quorum connections at startup on idle chains

After PR dashpay#7063 (commit 1360d9d), CQuorumManager::UpdatedBlockTip was
moved from CDSNotificationInterface::UpdatedBlockTip (which is called
directly at startup via InitializeCurrentBlockTip) to the
ActiveContext/ObserverContext CValidationInterface subscribers. These
subscribers only receive UpdatedBlockTip via GetMainSignals() broadcast,
which is never triggered at startup on idle chains — ActivateBestChain
early-returns when pindexMostWork == m_chain.Tip().

This means that after a full restart with no new blocks:
- QuorumObserver::UpdatedBlockTip never fires
- CheckQuorumConnections is never called
- Quorum connections are never re-established
- MNs cannot exchange signing shares
- InstantSend and ChainLock signing fails

Fix by adding InitializeCurrentBlockTip() to ActiveContext and
ObserverContext, called from the loadblk thread right after
CDSNotificationInterface::InitializeCurrentBlockTip(). This method
also calls the new QuorumObserver::InitializeQuorumConnections(),
which bypasses the IsBlockchainSynced() guard (mnsync is not yet
complete at that point in the startup sequence).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: UdjinM6

src/active/context.cpp

@@ -97,6 +97,14 @@ void ActiveContext::SetCJServer(gsl::not_null<CCoinJoinServer*> cj_server)
     m_cj_server = cj_server;
 }
 
+void ActiveContext::InitializeCurrentBlockTip(const CBlockIndex* tip, bool ibd)
+{
+    UpdatedBlockTip(tip, nullptr, ibd);
+    if (tip) {
+        qman_handler->InitializeQuorumConnections(tip);
+    }
+}
+
 void ActiveContext::UpdatedBlockTip(const CBlockIndex* pindexNew, const CBlockIndex* pindexFork, bool fInitialDownload)
 {
     if (fInitialDownload || pindexNew == pindexFork) // In IBD or blocks were disconnected without any new ones

src/active/context.h

@@ -74,6 +74,7 @@ struct ActiveContext final : public CValidationInterface {
 
     void Start(CConnman& connman, PeerManager& peerman, int16_t worker_count);
     void Stop();
+    void InitializeCurrentBlockTip(const CBlockIndex* tip, bool ibd);
 
     CCoinJoinServer& GetCJServer() const;
     void SetCJServer(gsl::not_null<CCoinJoinServer*> cj_server);

src/init.cpp

@@ -2417,6 +2417,15 @@ bool AppInitMain(NodeContext& node, interfaces::BlockAndHeaderTipInfo* tip_info)
         // but don't call it directly to prevent triggering of other listeners like zmq etc.
         // GetMainSignals().UpdatedBlockTip(::ChainActive().Tip());
         g_ds_notification_interface->InitializeCurrentBlockTip();
+        {
+            const CBlockIndex* tip = WITH_LOCK(::cs_main, return chainman.ActiveTip());
+            const bool ibd = chainman.ActiveChainstate().IsInitialBlockDownload();
+            if (node.active_ctx) {
+                node.active_ctx->InitializeCurrentBlockTip(tip, ibd);
+            } else if (node.observer_ctx) {
+                node.observer_ctx->InitializeCurrentBlockTip(tip, ibd);
+            }
+        }
 
         {
             // Get all UTXOs for each MN collateral in one go so that we can fill coin cache early

src/llmq/observer/context.cpp

@@ -47,6 +47,14 @@ void ObserverContext::Stop()
     qman_handler->Stop();
 }
 
+void ObserverContext::InitializeCurrentBlockTip(const CBlockIndex* tip, bool ibd)
+{
+    UpdatedBlockTip(tip, nullptr, ibd);
+    if (tip) {
+        qman_handler->InitializeQuorumConnections(tip);
+    }
+}
+
 void ObserverContext::UpdatedBlockTip(const CBlockIndex* pindexNew, const CBlockIndex* pindexFork, bool fInitialDownload)
 {
     if (fInitialDownload || pindexNew == pindexFork) // In IBD or blocks were disconnected without any new ones

src/llmq/observer/context.h

@@ -49,6 +49,7 @@ struct ObserverContext final : public CValidationInterface {
 
     void Start(int16_t worker_count);
     void Stop();
+    void InitializeCurrentBlockTip(const CBlockIndex* tip, bool ibd);
 
 protected:
     // CValidationInterface

src/llmq/observer/quorums.cpp

@@ -59,6 +59,13 @@ void QuorumObserver::Stop()
     workerPool.stop(true);
 }
 
+void QuorumObserver::InitializeQuorumConnections(gsl::not_null<const CBlockIndex*> pindexNew) const
+{
+    for (const auto& params : Params().GetConsensus().llmqs) {
+        CheckQuorumConnections(params, pindexNew);
+    }
+}
+
 void QuorumObserver::UpdatedBlockTip(const CBlockIndex* pindexNew, bool fInitialDownload) const
 {
     if (!pindexNew) return;

src/llmq/observer/quorums.h

@@ -96,6 +96,7 @@ class QuorumObserver
     void Stop();
 
     void UpdatedBlockTip(const CBlockIndex* pindexNew, bool fInitialDownload) const;
+    void InitializeQuorumConnections(gsl::not_null<const CBlockIndex*> pindexNew) const;
 
 public:
     virtual bool SetQuorumSecretKeyShare(CQuorum& quorum, Span<CBLSSecretKey> skContributions) const;