feat(ui): error & state UX — error surface, view states, map selection, sheet gestures (F4)

- lib/error/: classify any caught error into a stable ErrorKind from the
  transport signal (HTTP status / Connect Code / fetch TypeError /
  navigator.onLine); map to translated error.* messages via reportError
  (sticky Retry toast for retryable kinds) or errorMessageKey (inline).
  Mail compose now surfaces the translated 403/error inline.
- lib/ui/view-state.svelte: shared loading/empty/error placeholder with
  the right live-region role + optional action; entity tables
  (races/sciences/ship-classes) migrated, rest adopt incrementally.
- map/selection-ring.ts: accent ring around the selected planet, fed into
  the map buildExtras alongside the reach circles.
- lib/ui/sheet-dismiss.ts: tap-outside + drag-handle swipe-down dismissal
  for the planet/ship-group bottom-sheets (hand-rolled pointer events).

Tests: error, view-state, selection-ring, sheet-dismiss (761 total).
Docs: ui/docs/error-state-ux.md (+ index); F4 marked done.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

ui/frontend/src/lib/active-view/mail/compose.svelte

@@ -11,6 +11,7 @@ surfaces the resulting 403 inline.
 
 	import { i18n } from "$lib/i18n/index.svelte";
 	import { trapFocus } from "$lib/a11y/focus-trap";
+	import { errorMessageKey } from "$lib/error";
 	import { mailStore } from "$lib/mail-store.svelte";
 	import {
 		RENDERED_REPORT_CONTEXT_KEY,
@@ -82,7 +83,7 @@ surfaces the resulting 403 inline.
 			await mailStore.composeBroadcast({ subject, body: bodyText });
 			onSent(null);
 		} catch (err) {
-			error = err instanceof Error ? err.message : String(err);
+			error = i18n.t(errorMessageKey(err));
 		} finally {
 			sending = false;
 		}

ui/frontend/src/lib/active-view/map.svelte

@@ -32,6 +32,7 @@ preference the store already manages.
 	import { buildCargoRouteLines } from "../../map/cargo-routes";
 	import { buildPendingSendLines } from "../../map/pending-send-routes";
 	import { computeReachCircles } from "../../map/reach-circles";
+	import { computeSelectionRing } from "../../map/selection-ring";
 	import { reachStore } from "$lib/calculator/reach.svelte";
 	import {
 		reportToWorld,
@@ -202,6 +203,8 @@ preference the store already manages.
 		// redraw as the design or the selected planet changes.
 		void reachStore.origin;
 		void reachStore.speedPerTurn;
+		// Redraw the selected-planet ring when the selection changes.
+		void selection?.selected;
 
 		// Phase 29 visibility derivation. Cargo routes and pending-
 		// Send overlay are extras (no Pixi remount on flip); the
@@ -231,9 +234,11 @@ preference the store already manages.
 			reachOrigin === null
 				? ""
 				: `${reachOrigin.x},${reachOrigin.y},${reachStore.speedPerTurn}`;
+		const selectedPlanetId =
+			selection?.selected?.kind === "planet" ? selection.selected.id : null;
 		const extrasFingerprint =
 			`cr=${toggles.cargoRoutes ? "1" : "0"}|hp=${hiddenPlanetFingerprint}|` +
-			`reach=${reachFingerprint}|` +
+			`reach=${reachFingerprint}|sel=${selectedPlanetId ?? ""}|` +
 			computeRoutesFingerprint(report.routes) +
 			"|" +
 			computePendingSendFingerprint(draftCommands, draftStatuses);
@@ -329,7 +334,15 @@ preference the store already manages.
 						mode,
 					)
 				: [];
-		return [...cargo, ...pending, ...reach];
+		const selectedPlanetId =
+			selection?.selected?.kind === "planet" ? selection.selected.id : null;
+		const selectionRing = computeSelectionRing(report.planets, selectedPlanetId);
+		return [
+			...cargo,
+			...pending,
+			...reach,
+			...(selectionRing === null ? [] : [selectionRing]),
+		];
 	}
 
 	function applyVisibilityState(

ui/frontend/src/lib/active-view/table-races.svelte

@@ -34,6 +34,7 @@ data fetching is performed here — the layout is responsible.
 		OrderDraftStore,
 	} from "../../sync/order-draft.svelte";
 	import type { Relation } from "../../sync/order-types";
+	import ViewState from "$lib/ui/view-state.svelte";
 
 	type SortColumn =
 		| "name"
@@ -227,13 +228,17 @@ data fetching is performed here — the layout is responsible.
 	</header>
 
 	{#if !reportLoaded}
-		<p class="status" data-testid="races-loading">
-			{i18n.t("game.table.races.loading")}
-		</p>
+		<ViewState
+			kind="loading"
+			testid="races-loading"
+			message={i18n.t("game.table.races.loading")}
+		/>
 	{:else if races.length === 0}
-		<p class="status" data-testid="races-empty">
-			{i18n.t("game.table.races.empty")}
-		</p>
+		<ViewState
+			kind="empty"
+			testid="races-empty"
+			message={i18n.t("game.table.races.empty")}
+		/>
 	{:else}
 		<table class="grid" data-testid="races-table">
 			<thead>
@@ -388,11 +393,6 @@ data fetching is performed here — the layout is responsible.
 		flex: 1 1 12rem;
 		min-width: 8rem;
 	}
-	.status {
-		margin: 0;
-		color: var(--color-text-muted);
-		font-size: 0.9rem;
-	}
 	.grid {
 		border-collapse: collapse;
 		width: 100%;

ui/frontend/src/lib/active-view/table-sciences.svelte

@@ -23,6 +23,7 @@ data fetching is performed here — the layout is responsible.
 
 	import type { ScienceSummary } from "../../api/game-state";
 	import { i18n, type TranslationKey } from "$lib/i18n/index.svelte";
+	import ViewState from "$lib/ui/view-state.svelte";
 	import {
 		RENDERED_REPORT_CONTEXT_KEY,
 		type RenderedReportSource,
@@ -160,13 +161,17 @@ data fetching is performed here — the layout is responsible.
 	</header>
 
 	{#if !reportLoaded}
-		<p class="status" data-testid="sciences-loading">
-			{i18n.t("game.table.sciences.loading")}
-		</p>
+		<ViewState
+			kind="loading"
+			testid="sciences-loading"
+			message={i18n.t("game.table.sciences.loading")}
+		/>
 	{:else if localScience.length === 0}
-		<p class="status" data-testid="sciences-empty">
-			{i18n.t("game.table.sciences.empty")}
-		</p>
+		<ViewState
+			kind="empty"
+			testid="sciences-empty"
+			message={i18n.t("game.table.sciences.empty")}
+		/>
 	{:else}
 		<table class="grid" data-testid="sciences-table">
 			<thead>
@@ -271,11 +276,6 @@ data fetching is performed here — the layout is responsible.
 		color: var(--color-text);
 		border-color: var(--color-accent);
 	}
-	.status {
-		margin: 0;
-		color: var(--color-text-muted);
-		font-size: 0.9rem;
-	}
 	.grid {
 		border-collapse: collapse;
 		width: 100%;

ui/frontend/src/lib/active-view/table-ship-classes.svelte

@@ -26,6 +26,7 @@ data fetching is performed here — the layout is responsible.
 		OrderDraftStore,
 	} from "../../sync/order-draft.svelte";
 	import { calculatorLoadRequest } from "$lib/calculator/load-request.svelte";
+	import ViewState from "$lib/ui/view-state.svelte";
 
 	type SortColumn =
 		| "name"
@@ -154,13 +155,17 @@ data fetching is performed here — the layout is responsible.
 	</header>
 
 	{#if !reportLoaded}
-		<p class="status" data-testid="ship-classes-loading">
-			{i18n.t("game.table.ship_classes.loading")}
-		</p>
+		<ViewState
+			kind="loading"
+			testid="ship-classes-loading"
+			message={i18n.t("game.table.ship_classes.loading")}
+		/>
 	{:else if localShipClass.length === 0}
-		<p class="status" data-testid="ship-classes-empty">
-			{i18n.t("game.table.ship_classes.empty")}
-		</p>
+		<ViewState
+			kind="empty"
+			testid="ship-classes-empty"
+			message={i18n.t("game.table.ship_classes.empty")}
+		/>
 	{:else}
 		<table class="grid" data-testid="ship-classes-table">
 			<thead>
@@ -262,11 +267,6 @@ data fetching is performed here — the layout is responsible.
 		color: var(--color-text);
 		border-color: var(--color-accent);
 	}
-	.status {
-		margin: 0;
-		color: var(--color-text-muted);
-		font-size: 0.9rem;
-	}
 	.grid {
 		border-collapse: collapse;
 		width: 100%;

ui/frontend/src/lib/error/classify.ts

@@ -0,0 +1,93 @@
+/**
+ * Error classification.
+ *
+ * Server `result_code`s are downstream-opaque (only `"ok"` is a stable
+ * contract — see `docs/ARCHITECTURE.md`), so the client cannot key UX off
+ * them. Instead every caught error is collapsed into a small, stable set
+ * of client-side kinds, derived from the transport-level signal that IS
+ * reliable: HTTP status (`AuthError`), the Connect `Code`, a fetch
+ * `TypeError`, or the live `navigator.onLine` flag.
+ */
+
+import { ConnectError, Code } from "@connectrpc/connect";
+import { AuthError } from "../../api/auth";
+
+/** A stable, user-facing classification of any caught error. */
+export type ErrorKind =
+	| "offline"
+	| "network"
+	| "auth"
+	| "forbidden"
+	| "conflict"
+	| "notFound"
+	| "rateLimit"
+	| "server"
+	| "unknown";
+
+function fromHttpStatus(status: number): ErrorKind {
+	if (status === 401) return "auth";
+	if (status === 403) return "forbidden";
+	if (status === 404) return "notFound";
+	if (status === 409) return "conflict";
+	if (status === 429) return "rateLimit";
+	if (status >= 500) return "server";
+	return "unknown";
+}
+
+function fromConnectCode(code: Code): ErrorKind {
+	switch (code) {
+		case Code.Unauthenticated:
+			return "auth";
+		case Code.PermissionDenied:
+			return "forbidden";
+		case Code.NotFound:
+			return "notFound";
+		case Code.AlreadyExists:
+		case Code.Aborted:
+		case Code.FailedPrecondition:
+			return "conflict";
+		case Code.ResourceExhausted:
+			return "rateLimit";
+		case Code.Unavailable:
+			return "network";
+		case Code.Internal:
+		case Code.DataLoss:
+		case Code.Unknown:
+			return "server";
+		default:
+			return "unknown";
+	}
+}
+
+function hasNumericStatus(err: unknown): err is { status: number } {
+	return (
+		typeof err === "object" &&
+		err !== null &&
+		typeof (err as { status?: unknown }).status === "number"
+	);
+}
+
+/** Collapse any caught value into a stable {@link ErrorKind}. */
+export function classifyError(err: unknown): ErrorKind {
+	if (typeof navigator !== "undefined" && navigator.onLine === false) {
+		return "offline";
+	}
+	if (err instanceof AuthError) return fromHttpStatus(err.status);
+	if (err instanceof ConnectError) return fromConnectCode(err.code);
+	if (err instanceof TypeError && /fetch|network|load failed/i.test(err.message)) {
+		return "network";
+	}
+	if (hasNumericStatus(err)) return fromHttpStatus(err.status);
+	return "unknown";
+}
+
+const RETRYABLE: ReadonlySet<ErrorKind> = new Set<ErrorKind>([
+	"offline",
+	"network",
+	"server",
+]);
+
+/** Whether retrying the same operation could plausibly succeed. */
+export function isRetryable(kind: ErrorKind): boolean {
+	return RETRYABLE.has(kind);
+}

ui/frontend/src/lib/error/index.ts

@@ -0,0 +1,8 @@
+/**
+ * Central error surface: classify caught errors into stable client kinds
+ * and turn them into translated, actionable feedback. See `classify.ts`
+ * for the taxonomy and `report.ts` for the toast/inline helpers.
+ */
+
+export { classifyError, isRetryable, type ErrorKind } from "./classify";
+export { reportError, errorMessageKey, type ReportErrorOptions } from "./report";

ui/frontend/src/lib/error/report.ts

@@ -0,0 +1,57 @@
+/**
+ * Error reporting surface.
+ *
+ * Maps a classified {@link ErrorKind} to a translated, actionable message
+ * and either raises it as a toast (with a Retry action for retryable
+ * kinds) or hands the message key back for a view to render inline.
+ */
+
+import { toast } from "../toast.svelte";
+import type { TranslationKey } from "../i18n/index.svelte";
+import { classifyError, isRetryable, type ErrorKind } from "./classify";
+
+const MESSAGE_KEY: Record<ErrorKind, TranslationKey> = {
+	offline: "error.offline",
+	network: "error.network",
+	auth: "error.auth",
+	forbidden: "error.forbidden",
+	conflict: "error.conflict",
+	notFound: "error.not_found",
+	rateLimit: "error.rate_limit",
+	server: "error.server",
+	unknown: "error.unknown",
+};
+
+/** The translated message key for an error, for inline rendering. */
+export function errorMessageKey(err: unknown): TranslationKey {
+	return MESSAGE_KEY[classifyError(err)];
+}
+
+export interface ReportErrorOptions {
+	/**
+	 * Retry callback. When supplied and the error kind is retryable, the
+	 * toast gains a Retry action and stays until dismissed; otherwise the
+	 * toast auto-dismisses.
+	 */
+	onRetry?: () => void;
+}
+
+/**
+ * Classify `err`, raise a translated toast, and return the kind. A
+ * retryable error with an `onRetry` handler shows a sticky toast with a
+ * Retry action; everything else auto-dismisses.
+ */
+export function reportError(
+	err: unknown,
+	options: ReportErrorOptions = {},
+): ErrorKind {
+	const kind = classifyError(err);
+	const withRetry = options.onRetry !== undefined && isRetryable(kind);
+	toast.show({
+		messageKey: MESSAGE_KEY[kind],
+		actionLabelKey: withRetry ? "common.retry" : undefined,
+		onAction: withRetry ? options.onRetry : undefined,
+		durationMs: withRetry ? null : 8000,
+	});
+	return kind;
+}

ui/frontend/src/lib/i18n/locales/en.ts

@@ -9,10 +9,23 @@ const en = {
 	"common.loading": "loading…",
 	"common.dismiss": "dismiss",
 	"common.skip_to_content": "skip to main content",
+	"common.retry": "retry",
 	"common.browser_not_supported_title": "browser not supported",
 	"common.browser_not_supported_body":
 		"Galaxy requires Ed25519 in WebCrypto. See supported browsers.",
 
+	"error.offline":
+		"You appear to be offline. Check your connection and try again.",
+	"error.network": "Couldn't reach the server. Please try again.",
+	"error.auth": "Your session has expired. Please sign in again.",
+	"error.forbidden": "You don't have permission to do that.",
+	"error.conflict":
+		"This changed since you loaded it. Refresh and try again.",
+	"error.not_found": "Not found — it may have been removed.",
+	"error.rate_limit": "Too many requests. Wait a moment and try again.",
+	"error.server": "The server ran into a problem. Please try again.",
+	"error.unknown": "Something went wrong.",
+
 	"game.events.turn_ready.message": "turn {turn} is ready",
 	"game.events.turn_ready.action": "view now",
 	"game.events.signature_failed": "verification failed, reconnecting…",

ui/frontend/src/lib/i18n/locales/ru.ts

@@ -10,10 +10,23 @@ const ru: Record<keyof typeof en, string> = {
 	"common.loading": "загрузка…",
 	"common.dismiss": "закрыть",
 	"common.skip_to_content": "к основному содержимому",
+	"common.retry": "повторить",
 	"common.browser_not_supported_title": "браузер не поддерживается",
 	"common.browser_not_supported_body":
 		"Galaxy требует поддержки Ed25519 в WebCrypto. См. список поддерживаемых браузеров.",
 
+	"error.offline":
+		"Похоже, вы офлайн. Проверьте соединение и повторите попытку.",
+	"error.network": "Не удалось связаться с сервером. Повторите попытку.",
+	"error.auth": "Сессия истекла. Войдите снова.",
+	"error.forbidden": "Недостаточно прав для этого действия.",
+	"error.conflict":
+		"Данные изменились с момента загрузки. Обновите и повторите.",
+	"error.not_found": "Не найдено — возможно, удалено.",
+	"error.rate_limit": "Слишком много запросов. Подождите немного и повторите.",
+	"error.server": "На сервере произошла ошибка. Повторите попытку.",
+	"error.unknown": "Что-то пошло не так.",
+
 	"game.events.turn_ready.message": "ход {turn} готов",
 	"game.events.turn_ready.action": "открыть",
 	"game.events.signature_failed": "подпись повреждена, переподключение…",

ui/frontend/src/lib/inspectors/planet-sheet.svelte

@@ -20,6 +20,7 @@ dismiss from the IA section §6 land in Phase 35 polish.
 		ShipClassSummary,
 	} from "../../api/game-state";
 	import { i18n } from "$lib/i18n/index.svelte";
+	import { sheetDismiss } from "$lib/ui/sheet-dismiss";
 	import Planet from "./planet.svelte";
 
 	type Props = {
@@ -59,7 +60,9 @@ dismiss from the IA section §6 land in Phase 35 polish.
 		class="sheet"
 		aria-label={i18n.t("game.sidebar.tab.inspector")}
 		data-testid="inspector-planet-sheet"
+		use:sheetDismiss={{ onDismiss: onClose }}
 	>
+		<div class="grabber" data-sheet-handle aria-hidden="true"></div>
 		<button
 			type="button"
 			class="close"
@@ -105,6 +108,16 @@ dismiss from the IA section §6 land in Phase 35 polish.
 			z-index: 40;
 		}
 	}
+	.grabber {
+		display: block;
+		width: 2.5rem;
+		height: 0.25rem;
+		margin: 0.4rem auto 0.2rem;
+		border-radius: var(--radius-pill);
+		background: var(--color-border-strong);
+		touch-action: none;
+		cursor: grab;
+	}
 	.close {
 		position: absolute;
 		top: 0.4rem;

ui/frontend/src/lib/inspectors/ship-group-sheet.svelte

@@ -12,6 +12,7 @@ mounted by the in-game shell layout only while the active tool is
 		ShipClassSummary,
 	} from "../../api/game-state";
 	import { i18n } from "$lib/i18n/index.svelte";
+	import { sheetDismiss } from "$lib/ui/sheet-dismiss";
 	import ShipGroup, { type ShipGroupSelection } from "./ship-group.svelte";
 
 	type Props = {
@@ -51,7 +52,9 @@ mounted by the in-game shell layout only while the active tool is
 		class="sheet"
 		aria-label={i18n.t("game.sidebar.tab.inspector")}
 		data-testid="inspector-ship-group-sheet"
+		use:sheetDismiss={{ onDismiss: onClose }}
 	>
+		<div class="grabber" data-sheet-handle aria-hidden="true"></div>
 		<button
 			type="button"
 			class="close"
@@ -97,6 +100,16 @@ mounted by the in-game shell layout only while the active tool is
 			z-index: 40;
 		}
 	}
+	.grabber {
+		display: block;
+		width: 2.5rem;
+		height: 0.25rem;
+		margin: 0.4rem auto 0.2rem;
+		border-radius: var(--radius-pill);
+		background: var(--color-border-strong);
+		touch-action: none;
+		cursor: grab;
+	}
 	.close {
 		position: absolute;
 		top: 0.4rem;

ui/frontend/src/lib/ui/sheet-dismiss.ts

@@ -0,0 +1,77 @@
+/**
+ * Mobile bottom-sheet dismissal gestures, hand-rolled on pointer events
+ * (no dependency). A Svelte action for the sheet element:
+ *
+ * - **tap-outside** — a pointer-down anywhere outside the sheet dismisses
+ *   it (the sheet is non-modal, so this is a convenience, not a guard);
+ * - **swipe-down** — dragging the sheet's `[data-sheet-handle]` grabber
+ *   down past a threshold dismisses it. The swipe starts only from the
+ *   handle, so it never fights the sheet's own content scrolling.
+ *
+ * `onDismiss` is re-read on `update`, so a changing handler stays current.
+ */
+
+export interface SheetDismissOptions {
+	onDismiss: () => void;
+}
+
+/** Downward drag distance (px) past which release dismisses the sheet. */
+const SWIPE_DISMISS_PX = 80;
+
+export function sheetDismiss(
+	node: HTMLElement,
+	options: SheetDismissOptions,
+): { update(next: SheetDismissOptions): void; destroy(): void } {
+	let opts = options;
+	const handle = node.querySelector<HTMLElement>("[data-sheet-handle]") ?? node;
+
+	function onDocumentPointerDown(event: PointerEvent): void {
+		const target = event.target;
+		if (target instanceof Node && node.contains(target)) return;
+		opts.onDismiss();
+	}
+
+	let dragging = false;
+	let startY = 0;
+	let pointerId = -1;
+
+	function onHandleDown(event: PointerEvent): void {
+		dragging = true;
+		startY = event.clientY;
+		pointerId = event.pointerId;
+		handle.setPointerCapture?.(event.pointerId);
+	}
+
+	function onPointerMove(event: PointerEvent): void {
+		if (!dragging || event.pointerId !== pointerId) return;
+		const dy = Math.max(0, event.clientY - startY);
+		node.style.transform = dy > 0 ? `translateY(${dy}px)` : "";
+	}
+
+	function onPointerUp(event: PointerEvent): void {
+		if (!dragging || event.pointerId !== pointerId) return;
+		const dy = event.clientY - startY;
+		dragging = false;
+		node.style.transform = "";
+		if (dy > SWIPE_DISMISS_PX) opts.onDismiss();
+	}
+
+	document.addEventListener("pointerdown", onDocumentPointerDown, true);
+	handle.addEventListener("pointerdown", onHandleDown);
+	window.addEventListener("pointermove", onPointerMove);
+	window.addEventListener("pointerup", onPointerUp);
+	window.addEventListener("pointercancel", onPointerUp);
+
+	return {
+		update(next: SheetDismissOptions): void {
+			opts = next;
+		},
+		destroy(): void {
+			document.removeEventListener("pointerdown", onDocumentPointerDown, true);
+			handle.removeEventListener("pointerdown", onHandleDown);
+			window.removeEventListener("pointermove", onPointerMove);
+			window.removeEventListener("pointerup", onPointerUp);
+			window.removeEventListener("pointercancel", onPointerUp);
+		},
+	};
+}

ui/frontend/src/lib/ui/view-state.svelte

@@ -0,0 +1,91 @@
+<!--
+Shared loading / empty / error placeholder for a view or panel. Gives
+every surface one consistent treatment and a11y semantics:
+
+- `loading` and `empty` announce politely (`role="status"`);
+- `error` announces assertively (`role="alert"`) and may carry a retry /
+  recovery action.
+
+Callers pass an already-translated `message` (and `actionLabel`); the
+component owns layout, the spinner, and the live-region role only.
+-->
+<script lang="ts">
+	type Props = {
+		kind: "loading" | "empty" | "error";
+		message: string;
+		actionLabel?: string;
+		onAction?: () => void;
+		testid?: string;
+	};
+	let { kind, message, actionLabel, onAction, testid }: Props = $props();
+</script>
+
+<div
+	class="view-state {kind}"
+	data-testid={testid}
+	data-kind={kind}
+	role={kind === "error" ? "alert" : "status"}
+>
+	{#if kind === "loading"}
+		<span class="spinner" aria-hidden="true"></span>
+	{/if}
+	<p class="message">{message}</p>
+	{#if actionLabel !== undefined && onAction !== undefined}
+		<button type="button" class="action" onclick={onAction}>
+			{actionLabel}
+		</button>
+	{/if}
+</div>
+
+<style>
+	.view-state {
+		display: flex;
+		flex-direction: column;
+		align-items: center;
+		justify-content: center;
+		gap: var(--space-3);
+		padding: var(--space-6) var(--space-4);
+		text-align: center;
+		color: var(--color-text-muted);
+		font-family: var(--font-sans);
+	}
+	.message {
+		margin: 0;
+		max-width: 32rem;
+		line-height: var(--leading-normal);
+	}
+	.view-state.error .message {
+		color: var(--color-danger);
+	}
+	.action {
+		font: inherit;
+		padding: var(--space-2) var(--space-4);
+		background: var(--color-surface-raised);
+		color: var(--color-text);
+		border: 1px solid var(--color-border);
+		border-radius: var(--radius-sm);
+		cursor: pointer;
+	}
+	.action:hover {
+		background: var(--color-surface-hover);
+		border-color: var(--color-border-strong);
+	}
+	.spinner {
+		width: 1.5rem;
+		height: 1.5rem;
+		border: 2px solid var(--color-border);
+		border-top-color: var(--color-accent);
+		border-radius: var(--radius-pill);
+		animation: view-state-spin 0.8s linear infinite;
+	}
+	@media (prefers-reduced-motion: reduce) {
+		.spinner {
+			animation-duration: 2s;
+		}
+	}
+	@keyframes view-state-spin {
+		to {
+			transform: rotate(360deg);
+		}
+	}
+</style>

ui/frontend/src/map/selection-ring.ts

@@ -0,0 +1,47 @@
+// Selected-planet marker. When the SelectionStore holds a planet, the
+// map draws one accent ring tight around it so the current selection is
+// visible on the canvas itself (the inspector/sheet show the detail).
+// Ship-group selection is intentionally not ringed here — groups are
+// addressed by report index and have no single stable map coordinate.
+
+import type { CirclePrim } from "./world";
+
+/** Planet marker radius in world units; mirrors `battle-markers.ts`. */
+const PLANET_RADIUS_WORLD = 6;
+/** The ring sits just outside the marker (and the bombing ring at +3). */
+const SELECTION_RING_RADIUS = PLANET_RADIUS_WORLD + 4;
+
+export const SELECTION_RING_COLOR = 0x6d8cff;
+/** High-bit prefix so the ring id never collides with planet numbers,
+ * route lines, reach rings (`0xb…`), or battle markers. */
+export const SELECTION_RING_ID = 0xc0000000;
+/** Below interactive primitives so it never wins a click. */
+const SELECTION_RING_PRIORITY = 0;
+
+/**
+ * computeSelectionRing returns one ring primitive centred on the selected
+ * planet, or `null` when nothing (or a non-planet) is selected or the
+ * planet is absent from the current report.
+ */
+export function computeSelectionRing(
+	planets: ReadonlyArray<{ number: number; x: number; y: number }>,
+	selectedPlanetId: number | null,
+): CirclePrim | null {
+	if (selectedPlanetId === null) return null;
+	const planet = planets.find((p) => p.number === selectedPlanetId);
+	if (planet === undefined) return null;
+	return {
+		kind: "circle",
+		id: SELECTION_RING_ID,
+		priority: SELECTION_RING_PRIORITY,
+		hitSlopPx: 0,
+		x: planet.x,
+		y: planet.y,
+		radius: SELECTION_RING_RADIUS,
+		style: {
+			strokeColor: SELECTION_RING_COLOR,
+			strokeAlpha: 0.95,
+			strokeWidthPx: 1.5,
+		},
+	};
+}