Helix follows the web Helix subset that makes sense in MAUI, not the full HTMX spec. This page is the honest list of what is missing, so you can plan around it instead of discovering it halfway through a build. Supported, but only partly FeatureThe subset you get Hx.Paramsnone only. You cannot include or exclude by name. Hx.Swap animationsfade, the four slide-* directions and scale. The height-based collapse and expand are deferred: they warn and swap instantly. Hx.TriggerNamed events plus once, changed, delay, throttle. The rest are ignored. Rough edges to design around These are not missing features, they are behaviors that will surprise you. Each is covered in detail on its own page. Border cannot be an inner target. It is neither a ContentView nor a Layout. Target a layout inside it. See Requests and Targeting.A failed request that was going to append replaces the target's contents with the error, because errors are placed with an inner swap. Declare an Hx.Notification slot on anything that appends. See Indicators and Errors.changed silently blocks every request on a control that has no value, such as a Label, a layout, or a bare MAUI Picker. It only works on inputs. See Triggers.Unfocused wires on anything but only fires on focusable controls. See Triggers.An unknown trigger event name silently becomes a tap. See Triggers.appear is not revealed. appear fires when the page comes into view and is implemented; revealed is about the element scrolling into the viewport and is not. An element low on a long page fires its appear as soon as the page opens. See Triggers.An error placed next to a trigger can land in the wrong Grid cell, overlapping the first cell rather than appearing below the trigger. Most likely on a Load More button using outer on this. An Hx.Notification slot avoids it. See Indicators and Errors.Id lookups are case-sensitive while almost everything else is not. See Attribute Reference.after does not give you infinite scroll on its own. See Requests and Targeting.