Select Position Keyframes

// Cavalry Script: Keyfast - Select position keyframes
// Behavior:
// - If keyframes are selected: keep only position keyframes selected (deselect all others)
// - If no keyframes selected but layers selected: select all position keyframes on those layers
// - If neither keyframes nor layers selected: select all position keyframes in the active composition

(function selectPositionKeyframes() {
    var POS_ATTRS = ["position", "position.x", "position.y", "position.z"]; // guard for 2D/3D

    var isPositionAttr = function(attrPath) {
        if (!attrPath || typeof attrPath !== "string") return false;
        var a = ("" + attrPath).toLowerCase();
        if (a === "position") return true;
        if (a.indexOf("position.") === 0) return true; // position.x/.y/.z
        if (a.indexOf(".position") !== -1) return true; // e.g., transforms.position
        if (a.indexOf("shapeposition") !== -1) return true; // some layer types
        return false;
    };

    var uniq = function(arr) {
        var m = {};
        var out = [];
        for (var i = 0; i < arr.length; i++) {
            var v = arr[i];
            if (!m[v]) { m[v] = true; out.push(v); }
        }
        return out;
    };

    var listPositionAttributes = function(layerId) {
        var attrs = [];
        // Prefer enumerating animated attrs to catch variant names
        try {
            var animated = (typeof api.getAnimatedAttributes === "function") ? (api.getAnimatedAttributes(layerId) || []) : [];
            for (var i = 0; i < animated.length; i++) if (isPositionAttr(animated[i])) attrs.push(animated[i]);
        } catch (_) {}
        // Ensure common fallbacks are included
        for (var j = 0; j < POS_ATTRS.length; j++) if (attrs.indexOf(POS_ATTRS[j]) === -1) attrs.push(POS_ATTRS[j]);