diff --git a/src/browser/forms.zig b/src/browser/forms.zig
index adb0ba2b..38f9f682 100644
--- a/src/browser/forms.zig
+++ b/src/browser/forms.zig
@@ -141,6 +141,19 @@ pub const FormInfo = struct {
     }
 };
 
+/// Populate backendNodeId on each form and its fields by registering
+/// their nodes in the given registry. Works with both CDP and MCP registries.
+pub fn registerNodes(forms_data: []FormInfo, registry: anytype) !void {
+    for (forms_data) |*form| {
+        const form_registered = try registry.register(form.node);
+        form.backendNodeId = form_registered.id;
+        for (form.fields) |*field| {
+            const field_registered = try registry.register(field.node);
+            field.backendNodeId = field_registered.id;
+        }
+    }
+}
+
 /// Collect all forms and their fields under `root`.
 /// Uses Form.getElements() to include fields outside the <form> that
 /// reference it via the form="id" attribute, matching browser behavior.
diff --git a/src/cdp/domains/lp.zig b/src/cdp/domains/lp.zig
index 43b1b47b..60dedda7 100644
--- a/src/cdp/domains/lp.zig
+++ b/src/cdp/domains/lp.zig
@@ -174,15 +174,7 @@ fn detectForms(cmd: anytype) !void {
         page,
     );
 
-    // Register form and field nodes for backendNodeId references
-    for (forms_data) |*form| {
-        const registered = try bc.node_registry.register(form.node);
-        form.backendNodeId = registered.id;
-        for (form.fields) |*field| {
-            const field_registered = try bc.node_registry.register(field.node);
-            field.backendNodeId = field_registered.id;
-        }
-    }
+    try lp.forms.registerNodes(forms_data, &bc.node_registry);
 
     return cmd.sendResult(.{
         .forms = forms_data,
diff --git a/src/mcp/tools.zig b/src/mcp/tools.zig
index 93b4cc7f..0734b367 100644
--- a/src/mcp/tools.zig
+++ b/src/mcp/tools.zig
@@ -471,16 +471,10 @@ fn handleDetectForms(server: *Server, arena: std.mem.Allocator, id: std.json.Val
         return server.sendError(id, .InternalError, "Failed to collect forms");
     };
 
-    // Register form and field nodes for backendNodeId references
-    for (forms_data) |*form| {
-        const form_registered = try server.node_registry.register(form.node);
-        form.backendNodeId = form_registered.id;
-
-        for (form.fields) |*field| {
-            const field_registered = try server.node_registry.register(field.node);
-            field.backendNodeId = field_registered.id;
-        }
-    }
+    lp.forms.registerNodes(forms_data, &server.node_registry) catch |err| {
+        log.err(.mcp, "form node registration failed", .{ .err = err });
+        return server.sendError(id, .InternalError, "Failed to register form nodes");
+    };
 
     var aw: std.Io.Writer.Allocating = .init(arena);
     try std.json.Stringify.value(forms_data, .{}, &aw.writer);