diff --git a/src/init.cpp b/src/init.cpp
index 2efc495..83077f5 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -1081,6 +1081,37 @@ bool AppInit2()
     if (!LoadBlockIndex())
         return InitError(_("Error loading blkindex.dat"));
 
+    // triangles fix (pitfall #61): initialize pindexFinalized from the
+    // hardcoded checkpoint on startup, BEFORE the daemon opens any peer
+    // connections or processes any block messages.
+    //
+    // Without this, pindexFinalized stays NULL on a fresh restart even when
+    // we have 2.2M blocks on disk, because the auto-checkpoint code in
+    // ActivateBestChain() at main.cpp:2459 only sets it when
+    // !IsInitialBlockDownload(). If the chain tip is more than 24h stale
+    // (which happens on every restart with a synced chain), IsInitialBlockDownload()
+    // returns true and pindexFinalized never gets set.
+    //
+    // The downstream reorg guard at main.cpp:2198 short-circuits when
+    // pindexFinalized is NULL, which allowed a 3,755-block minority fork
+    // to overwrite a healthy 2,206,004-block chain on 2026-06-16. Loading
+    // the hardcoded checkpoint from checkpoints.cpp (block 2,205,000) on
+    // startup means the reorg guard is always active whenever the
+    // checkpointed block is in our local mapBlockIndex.
+    {
+        CBlockIndex* pCheckpoint = Checkpoints::GetLastCheckpoint(mapBlockIndex);
+        if (pCheckpoint && pCheckpoint != pindexFinalized)
+        {
+            pindexFinalized = pCheckpoint;
+            printf("STARTUP-CHECKPOINT: pindexFinalized set to block %d (%s) from hardcoded checkpoint\n",
+                pindexFinalized->nHeight, pindexFinalized->GetBlockHash().ToString().substr(0,20).c_str());
+        }
+        else if (!pCheckpoint)
+        {
+            printf("STARTUP-CHECKPOINT: WARNING — hardcoded checkpoint not in local block index, pindexFinalized remains NULL\n");
+        }
+    }
+
     // If the block index is empty but blk0001.dat exists (bootstrap download),
     // fast-import: build the index directly from the block file without re-writing
     // data. Batches LevelDB commits every 200K blocks for speed.
diff --git a/src/main.cpp b/src/main.cpp
index e7d79ef..b4e8078 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -4471,11 +4471,28 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv)
             // backwards walk if pnext is null for any other reason (this
             // happens when LoadBlockIndex() didn't fully heal pnext links,
             // or the chain was bootstrapped from a snapshot).
+            //
+            // pitfall #61 guard: if pindexFinalized is set (from the startup
+            // hardcoded-checkpoint init in init.cpp), serve from there instead
+            // of genesis. This prevents a fork peer from feeding us their
+            // short chain back via getheaders — the peer only learns our
+            // canonical chain from the finalized point forward, and their
+            // conflicting fork gets rejected at the reorg check in
+            // Reorganize() because the fork point is below pindexFinalized.
             if (!locator.IsNull() && pindex == pindexGenesisBlock &&
                 pindexGenesisBlock && locator.GetTipHash() != pindexGenesisBlock->GetBlockHash())
             {
-                printf("WARNING: peer getheaders locator has no common blocks — serving headers from genesis (peer may be on a fork)\n");
-                pindex = pindexGenesisBlock;
+                if (pindexFinalized && pindexFinalized->pnext)
+                {
+                    printf("getheaders: fork detected from peer %s, serving headers from finalized block %d (not genesis) — pitfall #61 guard\n",
+                        pfrom->addr.ToString().c_str(), pindexFinalized->nHeight);
+                    pindex = pindexFinalized;
+                }
+                else
+                {
+                    printf("WARNING: peer getheaders locator has no common blocks — serving headers from genesis (peer may be on a fork)\n");
+                    pindex = pindexGenesisBlock;
+                }
             }
 
             if (pindex)