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diff --git a/desktop/modules/monitors/Mon.js b/desktop/modules/monitors/Mon.js
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+.pragma library
+// Copyright (C) 2026 Danilo M. <danix@danix.xyz>
+//
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License version 2 as
+// published by the Free Software Foundation.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// Pure helpers for the Monitors page, tested by test_mon.js under node.
+// No String.matchAll, Object.fromEntries or flatMap: the shell's engine has
+// none of them (AGENTS.md).
+
+// Hyprland's automatic positions, as the card offers them.
+const AUTO = ["auto", "auto-left", "auto-right", "auto-up", "auto-down",
+              "auto-center-left", "auto-center-right", "auto-center-up", "auto-center-down"];
+
+// availableModes ("1920x1080@120.00Hz") without the suffix, duplicates
+// dropped: the ASUS lists 120Hz twice.
+function modes(avail) {
+    const out = [];
+    for (const a of avail) {
+        const m = a.replace(/Hz$/, "");
+        if (!out.includes(m)) out.push(m);
+    }
+    return out;
+}
+
+// The entry of list at w x h with the refresh nearest r: refreshRate reads
+// 99.943 against a listed 99.94. Built from the numbers when none matches.
+function current(list, w, h, r) {
+    let best = "", dist = Infinity;
+    for (const m of list) {
+        const p = /^(\d+)x(\d+)@([\d.]+)$/.exec(m);
+        if (!p || +p[1] !== w || +p[2] !== h) continue;
+        const e = Math.abs(+p[3] - r);
+        if (e < dist) { dist = e; best = m; }
+    }
+    return best || w + "x" + h + "@" + r.toFixed(2);
+}
+
+// A monitor from hyprctl monitors -j as the page edits it. x and y are
+// where Hyprland put it, kept to draw an auto position.
+function draft(m) {
+    const list = modes(m.availableModes);
+    return { name: m.name, make: m.make, model: m.model, modes: list,
+             mode: current(list, m.width, m.height, m.refreshRate),
+             scale: String(m.scale), transform: m.transform, vrr: !!m.vrr,
+             position: m.x + "x" + m.y, x: m.x, y: m.y };
+}
+
+// Logical size: an odd transform is a quarter turn, scale divides.
+function size(mode, scale, transform) {
+    const p = /^(\d+)x(\d+)/.exec(mode);
+    let w = +p[1], h = +p[2];
+    if (transform % 2) { const t = w; w = h; h = t; }
+    return { w: w / +scale, h: h / +scale };
+}
+
+// The layout position: exact XxY, or where Hyprland last put an auto one.
+function xy(d) {
+    const p = /^(-?\d+)x(-?\d+)$/.exec(d.position);
+    return p ? { x: +p[1], y: +p[2] } : { x: d.x, y: d.y };
+}
+
+// One monitor as one Lua expression, for hyprctl eval and the file alike.
+function lua(d) {
+    return 'hl.monitor({ output = "' + d.name + '", mode = "' + d.mode + '", position = "' + d.position
+        + '", scale = "' + d.scale + '", transform = ' + d.transform + (d.vrr ? ", vrr = 1" : "") + " })";
+}
+
+const HEADER = "-- Monitors, written by the keystone settings window (Hyprland > Monitors).\n"
+    + "-- Rewritten whole on Keep: change them there, an edit here is replaced.\n";
+
+function file(list) {
+    return HEADER + list.map(d => "\n-- " + d.name + ": " + d.make + " " + d.model + "\n" + lua(d) + "\n").join("");
+}
+
+// The candidate within t of v nearest to it, else v.
+function nearest(v, cands, t) {
+    let best = v, dist = t;
+    for (const c of cands) {
+        if (Math.abs(c - v) <= dist) { dist = Math.abs(c - v); best = c; }
+    }
+    return best;
+}
+
+// r ({x, y, w, h}, logical) moved so an edge within t lies on an edge of one
+// of others: beside it, or aligned with it. Each axis on its own, rounded.
+function snap(r, others, t) {
+    const xs = [], ys = [];
+    for (const o of others) {
+        xs.push(o.x - r.w, o.x + o.w, o.x, o.x + o.w - r.w);
+        ys.push(o.y - r.h, o.y + o.h, o.y, o.y + o.h - r.h);
+    }
+    return { x: Math.round(nearest(r.x, xs, t)), y: Math.round(nearest(r.y, ys, t)) };
+}