diff --git a/web/lib/potato_mesh/application/data_processing.rb b/web/lib/potato_mesh/application/data_processing.rb
index d46aa30..aa0fc8a 100644
--- a/web/lib/potato_mesh/application/data_processing.rb
+++ b/web/lib/potato_mesh/application/data_processing.rb
@@ -171,16 +171,20 @@ module PotatoMesh
         return if existing
 
         long_name = "#{protocol_display_label(protocol)} #{short_id}"
+        default_role = case protocol
+          when "meshcore" then "COMPANION"
+          else "CLIENT_HIDDEN"
+          end
         heard_time = coerce_integer(heard_time)
         inserted = false
 
         with_busy_retry do
           db.execute(
             <<~SQL,
-            INSERT OR IGNORE INTO nodes(node_id,num,short_name,long_name,role,last_heard,first_heard)
-            VALUES (?,?,?,?,?,?,?)
+            INSERT OR IGNORE INTO nodes(node_id,num,short_name,long_name,role,last_heard,first_heard,protocol)
+            VALUES (?,?,?,?,?,?,?,?)
           SQL
-            [node_id, node_num, short_id, long_name, "CLIENT_HIDDEN", heard_time, heard_time],
+            [node_id, node_num, short_id, long_name, default_role, heard_time, heard_time, protocol],
           )
           inserted = db.changes.positive?
         end
diff --git a/web/lib/potato_mesh/application/database.rb b/web/lib/potato_mesh/application/database.rb
index ce0a9d5..7f9f762 100644
--- a/web/lib/potato_mesh/application/database.rb
+++ b/web/lib/potato_mesh/application/database.rb
@@ -147,6 +147,14 @@ module PotatoMesh
               db.execute("CREATE INDEX IF NOT EXISTS idx_nodes_long_name ON nodes(long_name)")
             end
           end
+
+          # Backfill #747: ensure_unknown_node previously omitted the protocol
+          # column and hardcoded role=CLIENT_HIDDEN, causing meshcore placeholder
+          # nodes to be stored as meshtastic/CLIENT_HIDDEN.  Fix both in one pass.
+          if node_columns.include?("protocol")
+            db.execute("UPDATE nodes SET protocol = 'meshcore' WHERE long_name LIKE 'Meshcore %' AND protocol = 'meshtastic'")
+            db.execute("UPDATE nodes SET role = 'COMPANION' WHERE protocol = 'meshcore' AND role = 'CLIENT_HIDDEN'")
+          end
         end
 
         message_table_exists = db.get_first_value(
diff --git a/web/spec/app_spec.rb b/web/spec/app_spec.rb
index 7aab983..778770b 100644
--- a/web/spec/app_spec.rb
+++ b/web/spec/app_spec.rb
@@ -3022,7 +3022,7 @@ RSpec.describe "Potato Mesh Sinatra app" do
         db.results_as_hash = true
         row = db.get_first_row(
           <<~SQL,
-          SELECT short_name, long_name, role, last_heard, first_heard
+          SELECT short_name, long_name, role, protocol, last_heard, first_heard
           FROM nodes
           WHERE node_id = ?
         SQL
@@ -3032,11 +3032,81 @@ RSpec.describe "Potato Mesh Sinatra app" do
         expect(row["short_name"]).to eq("ABCD")
         expect(row["long_name"]).to eq("Meshtastic ABCD")
         expect(row["role"]).to eq("CLIENT_HIDDEN")
+        expect(row["protocol"]).to eq("meshtastic")
         expect(row["last_heard"]).to eq(reference_time.to_i)
         expect(row["first_heard"]).to eq(reference_time.to_i)
       end
     end
 
+    it "stores meshcore protocol and COMPANION role for meshcore nodes" do
+      with_db do |db|
+        created = ensure_unknown_node(db, "!abcd1234", nil, heard_time: reference_time.to_i, protocol: "meshcore")
+        expect(created).to be_truthy
+      end
+
+      with_db(readonly: true) do |db|
+        db.results_as_hash = true
+        row = db.get_first_row(
+          <<~SQL,
+          SELECT short_name, long_name, role, protocol
+          FROM nodes
+          WHERE node_id = ?
+        SQL
+          ["!abcd1234"],
+        )
+
+        expect(row["short_name"]).to eq("1234")
+        expect(row["long_name"]).to eq("Meshcore 1234")
+        expect(row["role"]).to eq("COMPANION")
+        expect(row["protocol"]).to eq("meshcore")
+      end
+    end
+
+    it "defaults to meshtastic protocol and CLIENT_HIDDEN role" do
+      with_db do |db|
+        created = ensure_unknown_node(db, "!beef0000", nil)
+        expect(created).to be_truthy
+      end
+
+      with_db(readonly: true) do |db|
+        db.results_as_hash = true
+        row = db.get_first_row(
+          <<~SQL,
+          SELECT role, protocol
+          FROM nodes
+          WHERE node_id = ?
+        SQL
+          ["!beef0000"],
+        )
+
+        expect(row["role"]).to eq("CLIENT_HIDDEN")
+        expect(row["protocol"]).to eq("meshtastic")
+      end
+    end
+
+    it "falls back to CLIENT_HIDDEN for an unknown protocol" do
+      with_db do |db|
+        created = ensure_unknown_node(db, "!cafe9999", nil, protocol: "reticulum")
+        expect(created).to be_truthy
+      end
+
+      with_db(readonly: true) do |db|
+        db.results_as_hash = true
+        row = db.get_first_row(
+          <<~SQL,
+          SELECT role, protocol, long_name
+          FROM nodes
+          WHERE node_id = ?
+        SQL
+          ["!cafe9999"],
+        )
+
+        expect(row["role"]).to eq("CLIENT_HIDDEN")
+        expect(row["protocol"]).to eq("reticulum")
+        expect(row["long_name"]).to eq("Reticulum 9999")
+      end
+    end
+
     it "leaves timestamps nil when no receive time is provided" do
       with_db do |db|
         created = ensure_unknown_node(db, "!1111beef", nil)
diff --git a/web/spec/database_spec.rb b/web/spec/database_spec.rb
index b5864f6..f64505b 100644
--- a/web/spec/database_spec.rb
+++ b/web/spec/database_spec.rb
@@ -258,4 +258,53 @@ RSpec.describe PotatoMesh::App::Database do
 
     expect(column_names_for("instances")).to include("contact_link")
   end
+
+  it "backfills misclassified meshcore placeholder nodes" do
+    SQLite3::Database.new(PotatoMesh::Config.db_path) do |db|
+      db.execute(<<~SQL)
+        CREATE TABLE nodes(
+          node_id TEXT PRIMARY KEY, num INTEGER, short_name TEXT, long_name TEXT,
+          role TEXT, last_heard INTEGER, first_heard INTEGER,
+          protocol TEXT NOT NULL DEFAULT 'meshtastic', synthetic BOOLEAN NOT NULL DEFAULT 0
+        )
+      SQL
+      db.execute("CREATE TABLE messages(id INTEGER PRIMARY KEY)")
+
+      # Misclassified meshcore placeholder (bug #747)
+      db.execute(
+        "INSERT INTO nodes(node_id, short_name, long_name, role, protocol) VALUES (?, ?, ?, ?, ?)",
+        ["!aabb0001", "0001", "Meshcore 0001", "CLIENT_HIDDEN", "meshtastic"],
+      )
+
+      # Meshcore node where protocol self-healed but role did not
+      db.execute(
+        "INSERT INTO nodes(node_id, short_name, long_name, role, protocol) VALUES (?, ?, ?, ?, ?)",
+        ["!aabb0002", "0002", "SomeNode", "CLIENT_HIDDEN", "meshcore"],
+      )
+
+      # Meshtastic node that should remain untouched
+      db.execute(
+        "INSERT INTO nodes(node_id, short_name, long_name, role, protocol) VALUES (?, ?, ?, ?, ?)",
+        ["!aabb0003", "0003", "Meshtastic 0003", "CLIENT_HIDDEN", "meshtastic"],
+      )
+    end
+
+    harness_class.ensure_schema_upgrades
+
+    SQLite3::Database.new(PotatoMesh::Config.db_path, readonly: true) do |db|
+      db.results_as_hash = true
+
+      fixed_proto = db.get_first_row("SELECT protocol, role FROM nodes WHERE node_id = '!aabb0001'")
+      expect(fixed_proto["protocol"]).to eq("meshcore")
+      expect(fixed_proto["role"]).to eq("COMPANION")
+
+      fixed_role = db.get_first_row("SELECT protocol, role FROM nodes WHERE node_id = '!aabb0002'")
+      expect(fixed_role["protocol"]).to eq("meshcore")
+      expect(fixed_role["role"]).to eq("COMPANION")
+
+      untouched = db.get_first_row("SELECT protocol, role FROM nodes WHERE node_id = '!aabb0003'")
+      expect(untouched["protocol"]).to eq("meshtastic")
+      expect(untouched["role"]).to eq("CLIENT_HIDDEN")
+    end
+  end
 end