diff --git a/src/mesh/NodeDB.cpp b/src/mesh/NodeDB.cpp
index 6f87422f2cc..b152a4be4b8 100644
--- a/src/mesh/NodeDB.cpp
+++ b/src/mesh/NodeDB.cpp
@@ -3484,14 +3484,12 @@ void NodeDB::addFromContact(meshtastic_SharedContact contact)
         }
     }
     info->num = contact.node_num;
-    // CopyUserToNodeInfoLite assigns public_key unconditionally, and clients send add_contact before every
-    // DM - often from an entry that carries no key at all. A contact may still supply or update a full
-    // 32-byte key (that's what add_contact is for), but it must never *erase* a key we already hold, which
-    // would be persisted below and break subsequent DMs with PKI_SEND_FAIL_PUBLIC_KEY.
+    // CopyUserToNodeInfoLite assigns public_key unconditionally. A contact may supply or update a
+    // full key, but must never erase one we already hold - clients send add_contact before every DM.
     const meshtastic_NodeInfoLite_public_key_t storedKey = info->public_key;
     TypeConversions::CopyUserToNodeInfoLite(info, contact.user);
     if (storedKey.size == 32 && info->public_key.size != 32) {
-        LOG_INFO("Contact 0x%08x has no key, keep the stored one", contact.node_num);
+        LOG_DEBUG("Contact 0x%08x has no key, keep the stored one", contact.node_num);
         info->public_key = storedKey;
     }
     if (contact.should_ignore) {
diff --git a/test/test_nodedb_blocked/test_main.cpp b/test/test_nodedb_blocked/test_main.cpp
index 96d392cd854..85ff8eb28a7 100644
--- a/test/test_nodedb_blocked/test_main.cpp
+++ b/test/test_nodedb_blocked/test_main.cpp
@@ -1,5 +1,5 @@
-// Tests for the NodeDB hot-store migration and favourite/ignored (blocked)
-// retention paths - src/mesh/NodeDB.cpp.
+// Tests for the NodeDB hot-store migration, favourite/ignored (blocked)
+// retention, and addFromContact() public-key retention paths - src/mesh/NodeDB.cpp.
 #include "MeshTypes.h" // BEFORE TestUtil.h - provides WARM_NODE_COUNT / MAX_NUM_NODES via mesh-pb-constants.h
 #include "TestUtil.h"
 #include <unity.h>
@@ -14,6 +14,7 @@
 #if WARM_NODE_COUNT > 0
 
 #include "mesh/NodeDB.h"
+#include "mesh/generated/meshtastic/admin.pb.h" // meshtastic_SharedContact
 #include <cstring>
 
 // Subclass shim: exposes the private maintenance paths (via the friend
@@ -73,6 +74,30 @@ bool warmHasKey(NodeNum n)
     return db->copyPublicKey(n, k) && k.size == 32;
 }
 
+// Seed a hot-store node holding a full 32-byte key of repeated `fill`, copied out to `out`.
+void seedKeyedNode(NodeNum num, uint8_t fill, uint8_t out[32])
+{
+    db->push(num, /*last_heard=*/100, /*favorite=*/false, /*ignored=*/false, /*withUser=*/true, /*withKey=*/false);
+    meshtastic_NodeInfoLite *n = db->getMeshNode(num);
+    TEST_ASSERT_NOT_NULL(n);
+    n->public_key.size = 32;
+    memset(n->public_key.bytes, fill, 32);
+    memcpy(out, n->public_key.bytes, 32);
+}
+
+// An add_contact payload for `num` whose key is `size` bytes of repeated `fill`.
+meshtastic_SharedContact makeContact(NodeNum num, pb_size_t size, uint8_t fill)
+{
+    meshtastic_SharedContact c = meshtastic_SharedContact_init_zero;
+    c.node_num = num;
+    c.has_user = true;
+    strncpy(c.user.long_name, "Contact", sizeof(c.user.long_name) - 1);
+    strncpy(c.user.short_name, "ct", sizeof(c.user.short_name) - 1);
+    c.user.public_key.size = size;
+    memset(c.user.public_key.bytes, fill, size);
+    return c;
+}
+
 } // namespace
 
 void setUp(void)
@@ -280,6 +305,75 @@ static void test_removeNodeByNum_presentNodeOnFullDb(void)
     TEST_ASSERT_NOT_NULL(db->getMeshNode(8000 + MAX_NUM_NODES - 1)); // survivors kept
 }
 
+// addFromContact() runs CopyUserToNodeInfoLite, which assigns public_key unconditionally.
+// A keyless contact (clients send add_contact before every DM) must not erase a stored key.
+static void test_addFromContact_emptyKeyKeepsStoredKey(void)
+{
+    db->seedSelf();
+    const NodeNum num = 0xC0FFEE01;
+    uint8_t stored[32];
+    seedKeyedNode(num, 0xA5, stored);
+
+    db->addFromContact(makeContact(num, /*size=*/0, /*fill=*/0x00));
+
+    const meshtastic_NodeInfoLite *n = db->getMeshNode(num);
+    TEST_ASSERT_NOT_NULL(n);
+    TEST_ASSERT_EQUAL_UINT(32, n->public_key.size);
+    TEST_ASSERT_EQUAL_MEMORY(stored, n->public_key.bytes, 32);
+}
+
+// Same guard for a truncated key: anything short of 32 bytes is unusable for PKI,
+// so it must not displace a full stored key either.
+static void test_addFromContact_shortKeyKeepsStoredKey(void)
+{
+    db->seedSelf();
+    const NodeNum num = 0xC0FFEE02;
+    uint8_t stored[32];
+    seedKeyedNode(num, 0x5A, stored);
+
+    db->addFromContact(makeContact(num, /*size=*/4, /*fill=*/0x11));
+
+    const meshtastic_NodeInfoLite *n = db->getMeshNode(num);
+    TEST_ASSERT_NOT_NULL(n);
+    TEST_ASSERT_EQUAL_UINT(32, n->public_key.size);
+    TEST_ASSERT_EQUAL_MEMORY(stored, n->public_key.bytes, 32);
+}
+
+// Regression guard on the guard: a well-formed 32-byte contact key still replaces the
+// stored one. Refusing erasure must not harden into a blanket first-key-wins pin.
+static void test_addFromContact_fullKeyReplacesStoredKey(void)
+{
+    db->seedSelf();
+    const NodeNum num = 0xC0FFEE03;
+    uint8_t stored[32];
+    seedKeyedNode(num, 0x11, stored);
+    uint8_t incoming[32];
+    memset(incoming, 0x22, sizeof(incoming));
+
+    db->addFromContact(makeContact(num, /*size=*/32, /*fill=*/0x22));
+
+    const meshtastic_NodeInfoLite *n = db->getMeshNode(num);
+    TEST_ASSERT_NOT_NULL(n);
+    TEST_ASSERT_EQUAL_UINT(32, n->public_key.size);
+    TEST_ASSERT_EQUAL_MEMORY(incoming, n->public_key.bytes, 32);
+}
+
+// The ordinary add_contact case: a full key is stored on an entry that held none.
+static void test_addFromContact_fullKeyStoredWhenNoneHeld(void)
+{
+    db->seedSelf();
+    const NodeNum num = 0xC0FFEE04;
+    uint8_t incoming[32];
+    memset(incoming, 0x33, sizeof(incoming));
+
+    db->addFromContact(makeContact(num, /*size=*/32, /*fill=*/0x33));
+
+    const meshtastic_NodeInfoLite *n = db->getMeshNode(num);
+    TEST_ASSERT_NOT_NULL(n);
+    TEST_ASSERT_EQUAL_UINT(32, n->public_key.size);
+    TEST_ASSERT_EQUAL_MEMORY(incoming, n->public_key.bytes, 32);
+}
+
 NDB_TEST_ENTRY void setup()
 {
     initializeTestEnvironment();
@@ -296,6 +390,10 @@ NDB_TEST_ENTRY void setup()
     RUN_TEST(test_protectedCap_refusesBeyondLimit);
     RUN_TEST(test_removeNodeByNum_absentNodeOnFullDb);
     RUN_TEST(test_removeNodeByNum_presentNodeOnFullDb);
+    RUN_TEST(test_addFromContact_emptyKeyKeepsStoredKey);
+    RUN_TEST(test_addFromContact_shortKeyKeepsStoredKey);
+    RUN_TEST(test_addFromContact_fullKeyReplacesStoredKey);
+    RUN_TEST(test_addFromContact_fullKeyStoredWhenNoneHeld);
     exit(UNITY_END());
 }
 NDB_TEST_ENTRY void loop() {}