fix(web): the Charge now slider stops at the most Core can order

.changeset/ev-charge-now-slider-top-step.md

@@ -0,0 +1,5 @@
+---
+"ftw": patch
+---
+
+The Charge now slider in the EV charger dialog now stops at the most FTW can order. It took its top from the charger's maximum, so a 32 A one-phase charger whose levels stop at 3.7 kW read 6–32 A, "32 A · 7.4 kW" and "FTW received 32 A" while FTW charged at 16 A. When a charger has a list of levels, the top is now the highest level at or below its maximum: 16 A · 3.7 kW for that charger.

web/app.js

@@ -3556,7 +3556,7 @@
   }
 
   // buildManualChargeSection renders the Tesla-style manual override: an
-  // amp slider (range = the charger's min/max charge current) plus Start /
+  // amp slider (range = the charger's minimum up to evChargeNowTopW) plus Start /
   // Stop. Start pins a persistent manual hold at the slider's amps,
   // which overrides surplus_only and the plan (the fuse clamp still
   // applies); Stop clears the hold and drops back to whatever mode the
@@ -3568,6 +3568,20 @@
       lp.manual && (lp.manual.requested_w === 0 || lp.manual.state === "paused" || lp.manual.state === "pausing")));
   }
 
+  // evChargeNowTopW is the most a hold can order. Core treats the hold as a
+  // ceiling and floors it to the step table within max_charge_w, so a
+  // one-phase charger rated 7,360 W with a table that stops at 3,680 W
+  // charges at 16 A, not 32.
+  function evChargeNowTopW(lp) {
+    var maxW = (lp && lp.max_charge_w) || 0;
+    var steps = lp && Array.isArray(lp.allowed_steps_w) ? lp.allowed_steps_w : [];
+    var topW = 0;
+    steps.forEach(function (w) {
+      if (w > topW && (maxW <= 0 || w <= maxW)) topW = w;
+    });
+    return topW || maxW;
+  }
+
   function buildManualChargeSection(lp) {
     var phases = (lp && lp.phases) || 3;
     var voltage = (lp && lp.voltage_v) || 230;
@@ -3576,7 +3590,7 @@
     function aToW(a) { return Math.round(a * perA); }
 
     var minA = Math.max(1, Math.round(wToA((lp && lp.min_charge_w) || 0)) || 6);
-    var maxA = Math.round(wToA((lp && lp.max_charge_w) || 0)) || 16;
+    var maxA = Math.round(wToA(evChargeNowTopW(lp))) || 16;
     if (maxA <= minA) { maxA = minA + 1; }
 
     var active = !!(lp && lp.manual_active);

web/ev-charge-now-range.test.mjs

@@ -0,0 +1,90 @@
+import assert from 'node:assert/strict';
+import { readFileSync } from 'node:fs';
+import test from 'node:test';
+
+const source = readFileSync(new URL('./app.js', import.meta.url), 'utf8');
+const section = source.slice(
+  source.indexOf('function evIsPaused'),
+  source.indexOf('function sliderHeader'),
+);
+
+// Core treats a Charge now hold as a ceiling and floors it to the charger's
+// step table within max_charge_w. The slider must stop where Core does: a
+// one-phase charger rated 32 A with a 16 A table showed 6–32 A and
+// "32 A · 7.4 kW" while Core ordered 3,680 W (22 Oct 2026 rig).
+
+class FakeEl {
+  constructor(tag) {
+    this.tagName = tag.toUpperCase();
+    this.style = {};
+    this.children = [];
+    this.attributes = {};
+    this.listeners = {};
+    this.textContent = '';
+  }
+  setAttribute(k, v) { this.attributes[k] = String(v); }
+  appendChild(c) { this.children.push(c); return c; }
+  addEventListener(type, fn) { (this.listeners[type] ||= []).push(fn); }
+  cloneNode() { const c = new FakeEl(this.tagName); Object.assign(c.style, this.style); return c; }
+  fire(type) { for (const fn of this.listeners[type] || []) fn({ type }); }
+}
+
+function walk(el, out = []) {
+  out.push(el);
+  for (const c of el.children) walk(c, out);
+  return out;
+}
+
+function build(lp) {
+  const sent = [];
+  const evWrite = (path, opts) => { sent.push(JSON.parse(opts.body)); return new Promise(() => {}); };
+  const make = new Function('document', 'evWrite', 'refreshEvModalAfterWrite', section + '; return buildManualChargeSection;');
+  const ctl = make({ createElement: tag => new FakeEl(tag) }, evWrite, () => {})(lp);
+  const all = walk(ctl.el);
+  const slider = all.find(el => el.tagName === 'INPUT' && el.type === 'range');
+  const row = all.find(el => el.children.includes(slider));
+  return {
+    slider,
+    readout: row.children[1],
+    status: all.find(el => el.tagName === 'SMALL'),
+    start: all.find(el => el.tagName === 'BUTTON' && el.textContent === 'Charge now'),
+    sent,
+  };
+}
+
+const onePhase = {
+  id: 'garage', phases: 1, voltage_v: 230, plugged_in: true,
+  min_charge_w: 1380, max_charge_w: 7360, allowed_steps_w: [0, 1380, 2300, 3680],
+};
+
+test('a one-phase charger tops out at the top of its step table', () => {
+  const ui = build(onePhase);
+  assert.equal(ui.slider.min, '6');
+  assert.equal(ui.slider.max, '16');
+  assert.equal(ui.readout.textContent, '16 A · 3.7 kW');
+  assert.match(ui.status.textContent, /^Starts at up to 16 A · 3\.7 kW\./);
+  ui.start.fire('click');
+  assert.deepEqual(ui.sent, [{ power_w: 3680, hold_s: 0, phase_mode: '1p' }]);
+});
+
+test('a hold above the table reads as the top Core can order', () => {
+  const ui = build({ ...onePhase, manual_active: true, manual_charge_w: 7360 });
+  assert.equal(ui.slider.value, '16');
+  assert.equal(ui.readout.textContent, '16 A · 3.7 kW');
+});
+
+test('the top is the highest step within max_charge_w', () => {
+  const ui = build({
+    id: 'garage', phases: 3, voltage_v: 230, plugged_in: true,
+    min_charge_w: 4140, max_charge_w: 7360, allowed_steps_w: [0, 4140, 6900, 11040],
+  });
+  assert.equal(ui.slider.max, '10');
+  assert.equal(ui.readout.textContent, '10 A · 6.9 kW');
+});
+
+test('without a table the top is max_charge_w, as before', () => {
+  const ui = build({ id: 'garage', phases: 3, voltage_v: 230, min_charge_w: 4140, max_charge_w: 11040 });
+  assert.equal(ui.slider.min, '6');
+  assert.equal(ui.slider.max, '16');
+  assert.equal(ui.readout.textContent, '16 A · 11.0 kW');
+});