diff --git a/package.json b/package.json
index 70de9769..7435e0a7 100644
--- a/package.json
+++ b/package.json
@@ -44,10 +44,6 @@
         6
       ],
       "block-spacing": "error",
-      "array-bracket-spacing": [
-        "error",
-        "always"
-      ],
       "multiline-comment-style": "error",
       "computed-property-spacing": "off",
       "space-in-parens": "off",
diff --git a/public/assets/sandbox-ui.js b/public/assets/sandbox-ui.js
index 2603e6f3..e355577a 100644
--- a/public/assets/sandbox-ui.js
+++ b/public/assets/sandbox-ui.js
@@ -19,6 +19,63 @@ function sameAction(left, right) {
 		&& left.source === right.source;
 }
 
+/** Captures user-editable controls before dashboard markup is replaced. */
+function snapshotForm(form) {
+	const occurrences = new Map();
+	return Array.from(form.elements).flatMap((control) => {
+		if (!control.name || ['hidden', 'submit', 'button', 'reset', 'file'].includes(control.type)) {
+			return [];
+		}
+
+		const occurrence = occurrences.get(control.name) || 0;
+		occurrences.set(control.name, occurrence + 1);
+		return [{
+			name: control.name,
+			occurrence,
+			value: control.value,
+			checked: control.checked,
+			selected: control.options ? Array.from(control.options).filter((option) => option.selected).map((option) => option.value) : null,
+		}];
+	});
+}
+
+/** Finds the regenerated form without relying on mutable field values. */
+function actionForm(context) {
+	const candidates = Array.from(dashboard.querySelectorAll('form[data-ajax]')).filter((form) => {
+		const candidate = actionContext(form);
+		return candidate.action === context.action
+			&& candidate.board === context.board
+			&& candidate.section === context.section;
+	});
+
+	return candidates.find((form) => sameAction(actionContext(form), context)) || (candidates.length === 1 ? candidates[0] : null);
+}
+
+/** Restores submitted values after an error response regenerates the dashboard. */
+function restoreForm(context, snapshot) {
+	const form = actionForm(context);
+	if (!form) {
+		return;
+	}
+
+	for (const saved of snapshot) {
+		const controls = Array.from(form.elements).filter((control) => control.name === saved.name);
+		const control = controls[saved.occurrence];
+		if (!control) {
+			continue;
+		}
+		if (saved.selected !== null) {
+			for (const option of control.options) {
+				option.selected = saved.selected.includes(option.value);
+			}
+		} else if (control.type === 'checkbox' || control.type === 'radio') {
+			control.checked = saved.checked;
+		} else {
+			control.value = saved.value;
+		}
+	}
+}
+
 /** Reapplies pending state after AJAX replaces dashboard markup. */
 function syncPendingActions() {
 	pendingActions.forEach((pending) => {
@@ -136,6 +193,7 @@ function bindAjax() {
 			}
 
 			const context = actionContext(form);
+			const formSnapshot = snapshotForm(form);
 			const submitter = event.submitter;
 			const original = submitter ? submitter.innerHTML : '';
 			const actionId = nextActionId++;
@@ -170,6 +228,9 @@ function bindAjax() {
 				if (typeof data.html === 'string' && data.html !== '') {
 					dashboard.innerHTML = data.html;
 					bindAjax();
+					if (data.error) {
+						restoreForm(context, formSnapshot);
+					}
 					syncPendingActions();
 				}
 				showActionResult(data, context);
diff --git a/src/QuickInstall/Sandbox/Web/templates/dashboard.php b/src/QuickInstall/Sandbox/Web/templates/dashboard.php
index 07473ba9..491d3991 100644
--- a/src/QuickInstall/Sandbox/Web/templates/dashboard.php
+++ b/src/QuickInstall/Sandbox/Web/templates/dashboard.php
@@ -57,7 +57,7 @@
 	<div class="section-head">
 		<div>
 			<h2><svg class="icon" aria-hidden="true"><use href="#icon-boards"></use></svg>Boards</h2>
-			<p>Start, stop, seed, and inspect local Docker-backed phpBB installs.</p>
+			<p>Manage your local phpBB boards and add sample content.</p>
 		</div>
 	</div>
 	<?php if (!$boards): ?>
@@ -159,7 +159,7 @@
 	<div class="section-head">
 		<div>
 			<h2><svg class="icon" aria-hidden="true"><use href="#icon-create"></use></svg>Create board</h2>
-			<p>Choose the phpBB source, runtime, port, and optional seed preset.</p>
+			<p>Set up a new phpBB board for development or testing.</p>
 		</div>
 	</div>
 	<form method="post" class="card settings-form" data-ajax>
@@ -181,7 +181,7 @@
 	<div class="section-head">
 		<div>
 			<h2><svg class="icon" aria-hidden="true"><use href="#icon-customisations"></use></svg>Customisations</h2>
-			<p>Bind or copy local extension and style work into a board.</p>
+			<p>Add extensions and styles from your local projects.</p>
 		</div>
 	</div>
 	<div class="split">
@@ -209,7 +209,7 @@
 	<div class="section-head">
 		<div>
 			<h2><svg class="icon" aria-hidden="true"><use href="#icon-sources"></use></svg>Sources</h2>
-			<p>Fetch and inspect phpBB sources used by boards.</p>
+			<p>Manage the phpBB versions available for your boards.</p>
 		</div>
 	</div>
 	<form method="post" class="card settings-form compact-form joined-form" data-ajax>
@@ -264,7 +264,7 @@
 	<div class="section-head">
 		<div>
 			<h2><svg class="icon" aria-hidden="true"><use href="#icon-activity"></use></svg>Activity log</h2>
-			<p>Queued and completed actions from this browser session.</p>
+			<p>Review actions and results from this session.</p>
 		</div>
 		<button type="button" class="secondary" data-clear-log>Clear</button>
 	</div>
diff --git a/src/QuickInstall/Sandbox/Web/templates/layout.php b/src/QuickInstall/Sandbox/Web/templates/layout.php
index 7346e426..75ccd98d 100644
--- a/src/QuickInstall/Sandbox/Web/templates/layout.php
+++ b/src/QuickInstall/Sandbox/Web/templates/layout.php
@@ -46,7 +46,7 @@
 			<header class="topbar">
 				<div>
 					<h1>QuickInstall Dashboard</h1>
-					<p class="lede">Manage disposable phpBB boards backed by the same Docker services as the CLI.</p>
+					<p class="lede">Create and manage local phpBB boards for development and testing.</p>
 				</div>
 				<div class="actions">
 					<form method="post" data-ajax>
diff --git a/tests/Integration/WebApplicationTest.php b/tests/Integration/WebApplicationTest.php
index 1b747add..1de654c4 100644
--- a/tests/Integration/WebApplicationTest.php
+++ b/tests/Integration/WebApplicationTest.php
@@ -119,6 +119,10 @@ public function testDashboardJavascriptTracksConcurrentActions(): void
 		self::assertStringContainsString('entry.status = runningAssigned ? \'queued\' : \'running\';', $javascript);
 		self::assertStringContainsString("document.querySelectorAll('[data-mounted-toggle]')", $javascript);
 		self::assertStringContainsString("button.textContent = expanded ? button.dataset.moreLabel : 'Show less';", $javascript);
+		self::assertStringContainsString('const formSnapshot = snapshotForm(form);', $javascript);
+		self::assertStringContainsString('if (data.error) {', $javascript);
+		self::assertStringContainsString('restoreForm(context, formSnapshot);', $javascript);
+		self::assertStringContainsString("control.type === 'checkbox' || control.type === 'radio'", $javascript);
 	}
 
 	public function testNarrowBoardCardsStackMountedLists(): void