feat(web): Start Display on Boot toggle on the General tab

Turns ledmatrix.service's autostart on or off at once through the existing
enable_autostart / disable_autostart system actions (sudo grants already in
lib_sudoers.sh). The checkbox shows systemd's own state, read with
`systemctl is-enabled`, so nothing is stored in config.json and the default
stays on. Hidden when the state cannot be read; a refused change puts the
box back and shows the route's message.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

CHANGELOG.md

@@ -19,6 +19,16 @@ accepts both, but the store flags the old spelling as deprecated
 
 ## Unreleased
 
+### Features
+
+- General tab: a **Start Display on Boot** toggle turns
+  `ledmatrix.service`'s autostart on or off right away (no Save needed),
+  through the existing `enable_autostart` / `disable_autostart` system
+  actions. It shows systemd's own state, so nothing is stored in
+  `config.json`; the default stays on (the installer enables the unit). The
+  web interface still starts on boot either way. Hidden when the unit's state
+  cannot be read (not installed, or no systemd).
+
 ### Fixes
 
 - `SportsRankingsMixin` (#789's deferred review points, now that it is the

test/js/run_all.js

@@ -32,7 +32,8 @@ const UNIT = ['unit/test_list_filter.js', 'unit/test_render_cards.js',
               'unit/test_page_registry.js', 'unit/test_core_modules.js',
               'unit/test_overview_reconciliation_poll.js',
               'unit/test_display_partial_ids.js',
-              'unit/test_general_web_login_token.js'];
+              'unit/test_general_web_login_token.js',
+              'unit/test_general_display_autostart.js'];
 const DOM = ['dom/test_installed_dom.js', 'dom/test_store_dom.js', 'dom/test_no_double_fetch.js',
              'dom/test_tools_sections.js', 'dom/test_cache_page.js',
              'dom/test_durations_page.js', 'dom/test_operation_history_page.js',

test/js/unit/test_general_display_autostart.js

@@ -0,0 +1,77 @@
+// The General tab's "Start Display on Boot" checkbox (setDisplayAutostart in
+// static/v3/js/pages/general.js) posts enable_autostart / disable_autostart
+// to /api/v3/system/action and puts the box back when that is refused --
+// including the route's HTTP-200 {status: "error"} answer for a failed
+// systemctl (e.g. the sudo rule is missing).
+//
+// Fake fetch, no jsdom and no server needed.
+
+const path = require('path');
+const { pathToFileURL } = require('url');
+
+const JS = path.resolve(__dirname, '../../../web_interface/static/v3/js');
+const load = f => import(pathToFileURL(path.join(JS, f)).href);
+
+let pass = 0, fail = 0;
+const ok = (label, cond, extra) => cond
+  ? (pass++, console.log('  ok   ' + label))
+  : (fail++, console.log('  FAIL ' + label + (extra !== undefined ? '  ' + JSON.stringify(extra) : '')));
+
+async function run(checked, answer) {
+  const { createApi } = await load('core/api.js');
+  const general = await load('pages/general.js');
+  const sent = [];
+  const notes = [];
+  const fetch = (url, init) => {
+    sent.push([url, JSON.parse(init.body)]);
+    if (answer === 'network') return Promise.reject(new TypeError('Failed to fetch'));
+    return Promise.resolve({
+      ok: answer.ok, status: answer.ok ? 200 : 500,
+      headers: { get: () => null },
+      text: () => Promise.resolve(JSON.stringify(answer.body)),
+    });
+  };
+  const ctx = { root: {}, state: {}, signal: { aborted: false },
+                api: createApi({ fetch }), notify: (m, t) => notes.push([m, t]) };
+  const box = { checked, disabled: false };
+  await general.setDisplayAutostart(ctx, box);
+  return { box, sent, notes };
+}
+
+(async () => {
+  console.log('\n── General tab: Start Display on Boot ──');
+
+  {
+    const t = await run(false, { ok: true, body: { status: 'success', message: 'ok' } });
+    ok('unchecking posts disable_autostart',
+       t.sent.length === 1 && t.sent[0][0] === '/api/v3/system/action' && t.sent[0][1].action === 'disable_autostart', t.sent);
+    ok('...stays unchecked and re-enabled', t.box.checked === false && t.box.disabled === false);
+    ok('...and reports success', t.notes.some(([, type]) => type === 'success'), t.notes);
+  }
+
+  {
+    const t = await run(true, { ok: true, body: { status: 'success' } });
+    ok('checking posts enable_autostart', t.sent[0][1].action === 'enable_autostart', t.sent);
+  }
+
+  {
+    const t = await run(false, { ok: true, body: { status: 'error', message: 'sudo: a password is required' } });
+    ok('a failed systemctl (HTTP 200, status error) puts the box back', t.box.checked === true && !t.box.disabled);
+    ok('...and shows the route\'s message',
+       t.notes.some(([m, type]) => type === 'error' && /sudo/.test(m)), t.notes);
+  }
+
+  {
+    const t = await run(true, { ok: false, body: { status: 'error', message: 'boom' } });
+    ok('an HTTP error puts the box back', t.box.checked === false && !t.box.disabled);
+  }
+
+  {
+    const t = await run(true, 'network');
+    ok('a network failure puts the box back', t.box.checked === false && !t.box.disabled);
+    ok('...and reports it', t.notes.some(([, type]) => type === 'error'), t.notes);
+  }
+
+  console.log(`\n${pass} passed, ${fail} failed\n`);
+  process.exit(fail ? 1 : 0);
+})().catch(e => { console.log('HARNESS ERROR: ' + e.stack); process.exit(1); });

test/test_general_display_autostart.py

@@ -0,0 +1,60 @@
+"""The General tab's "Start Display on Boot" toggle reads systemd's state.
+
+ledmatrix.service enabled -> checked, disabled -> unchecked, unreadable (no
+systemctl, unit not installed) -> no toggle. The toggle itself posts the
+existing enable_autostart / disable_autostart system actions, whose sudo
+grants test_systemctl_sudoers_alignment.py already checks.
+"""
+import subprocess
+import sys
+from pathlib import Path
+
+import pytest
+
+PROJECT_ROOT = Path(__file__).parent.parent
+sys.path.insert(0, str(PROJECT_ROOT))
+
+from test.test_web_settings_ui import client  # noqa: F401,E402
+from web_interface.blueprints import pages_v3  # noqa: E402
+
+
+REAL_RUN = subprocess.run
+UNIT_QUERY = ['systemctl', 'is-enabled', 'ledmatrix.service']
+
+
+def _fake_systemctl(monkeypatch, answer):
+    """Answer the unit query with `answer` (stdout, or an exception to
+    raise); every other command (the update channel's git) runs for real."""
+    calls = []
+
+    def run(cmd, *args, **kwargs):
+        if cmd != UNIT_QUERY:
+            return REAL_RUN(cmd, *args, **kwargs)
+        calls.append(cmd)
+        if isinstance(answer, Exception):
+            raise answer
+        return subprocess.CompletedProcess(cmd, 0, stdout=answer, stderr='')
+    monkeypatch.setattr(pages_v3.subprocess, 'run', run)
+    return calls
+
+
+def _toggle(body):
+    start = body.find('data-action="display-autostart"')
+    return None if start < 0 else body[start:body.find('>', start)]
+
+
+@pytest.mark.parametrize('stdout, checked', [('enabled\n', True), ('disabled\n', False)])
+def test_toggle_reflects_the_unit(client, monkeypatch, stdout, checked):
+    calls = _fake_systemctl(monkeypatch, stdout)
+    tag = _toggle(client.get('/v3/partials/general').get_data(as_text=True))
+    assert calls == [UNIT_QUERY]
+    assert tag is not None
+    assert ('checked' in tag) is checked
+
+
+@pytest.mark.parametrize('outcome', [FileNotFoundError(), 'not-found\n'])
+def test_toggle_hidden_when_state_unreadable(client, monkeypatch, outcome):
+    _fake_systemctl(monkeypatch, outcome)
+    body = client.get('/v3/partials/general').get_data(as_text=True)
+    assert _toggle(body) is None
+    assert 'name="plugins_directory"' in body  # rest of the tab still renders

web_interface/blueprints/pages_v3.py

@@ -4,6 +4,7 @@ from html.parser import HTMLParser
 import json
 import logging
 import re
+import subprocess
 from pathlib import Path
 
 # Strict allowlists for URL-derived values used in path and script operations.
@@ -487,9 +488,25 @@ def _load_general_partial():
                              main_config=main_config,
                              auto_update_status=auto_update_status,
                              update_channel_status=update_channel_status,
+                             display_autostart=_display_autostart_state(),
                              web_login=_web_login_state())
 
 
+def _display_autostart_state():
+    """Whether ledmatrix.service starts at boot; None hides the toggle.
+
+    systemd's enablement is the setting itself (the installer enables the
+    unit), so nothing is stored in config.json. None when it cannot be read:
+    no systemctl (a dev machine) or the unit is not installed.
+    """
+    try:
+        result = subprocess.run(['systemctl', 'is-enabled', 'ledmatrix.service'],
+                                capture_output=True, text=True, timeout=5)
+    except (OSError, subprocess.SubprocessError):
+        return None
+    return {'enabled': True, 'disabled': False}.get(result.stdout.strip())
+
+
 def _web_login_state():
     """What the General tab's Security section shows; None hides it.
 

web_interface/static/v3/js/pages/general.js

@@ -191,6 +191,28 @@ export function revokeToken(ctx, id, name) {
     }).catch(failed(ctx));
 }
 
+/**
+ * The "Start Display on Boot" checkbox: enable or disable ledmatrix.service
+ * at once. A refusal (e.g. the sudo rule is missing) puts the box back.
+ */
+export function setDisplayAutostart(ctx, box) {
+    const on = box.checked;
+    box.disabled = true;
+    return send(ctx, 'POST', '/api/v3/system/action', { action: on ? 'enable_autostart' : 'disable_autostart' }).then(function(res) {
+        if (!res) return false;
+        const ok = res.ok && res.d.status === 'success';
+        if (!ok) box.checked = !on;
+        ctx.notify(ok ? (on ? 'The display will start on boot' : 'The display will not start on boot')
+                      : (res.d.message || 'Could not change display autostart'), ok ? 'success' : 'error');
+        return ok;
+    }).catch(function(err) {
+        box.checked = !on;
+        failed(ctx)(err);
+    }).finally(function() {
+        box.disabled = false;
+    });
+}
+
 const FORM_ACTIONS = { 'set-password': setPassword, 'disable-login': disableLogin, 'create-token': createToken };
 
 function drawTimezone(root, ctx) {
@@ -238,6 +260,10 @@ export function init(root, ctx) {
             if (row) revokeToken(ctx, row.dataset.tokenId, button.dataset.tokenName);
         }
     }, on);
+    root.addEventListener('change', function(event) {
+        const box = event.target;
+        if (box && box.dataset && box.dataset.action === 'display-autostart') setDisplayAutostart(ctx, box);
+    }, on);
     drawTimezone(root, ctx);
     active = ctx;
 }

web_interface/templates/v3/partials/general.html

@@ -12,6 +12,22 @@
 
     {{ ui.settings_filter() }}
 
+    {# Display autostart is systemd's enable/disable of ledmatrix.service, not a
+       config.json key: outside the form so Save never posts it. general.js
+       applies it on change. Hidden when the unit's state cannot be read. #}
+    {% if display_autostart is not none %}
+    <div class="form-group mb-6" id="setting-general-display_autostart" data-setting-key="display_autostart">
+        <label class="flex items-center">
+            <input type="checkbox"
+                   data-action="display-autostart"
+                   {% if display_autostart %}checked{% endif %}
+                   class="h-4 w-4 text-blue-600 focus:ring-blue-500 border-gray-300 rounded">
+            <span class="ml-2 text-sm font-medium text-gray-900">Start Display on Boot</span>
+            {{ ui.help_tip('Start the LED display automatically when the device powers on.\nApplies right away; no Save needed.\nWhen off, start it with Start Display on the Overview tab. The web interface still starts on boot.\nDefault: on.', 'Start Display on Boot') }}
+        </label>
+    </div>
+    {% endif %}
+
     <form hx-post="/api/v3/config/main"
           hx-ext="json-enc"
           hx-headers='{"Content-Type": "application/json"}'