ui/phase-13: planet inspector — read-only

Plumbs the map → inspector pathway: a click on a planet selects it
through the new SelectionStore, the sidebar Inspector tab swaps
its empty-state copy for a per-kind read-only field set, and a
mobile-only bottom-sheet mirrors the same content over the map.
Field projection in api/game-state.ts now surfaces every documented
planet field.

ui/frontend/src/routes/games/[id]/+layout.svelte

@@ -11,18 +11,36 @@ layout owns:
   so navigating to any other view through the More drawer or the
   header view-menu naturally drops the overlay even if `mobileTool`
   was set on a previous tap.
+- `activeTab` — current sidebar tool (`calculator` / `inspector` /
+  `order`). Held here, bound into the sidebar so a planet click on
+  the map can flip it to `inspector` from the outside (Phase 13).
+- Per-game stores: `GameStateStore`, `OrderDraftStore`, and the
+  Phase 13 `SelectionStore`. All three are exposed to descendants
+  via Svelte context; their lifetimes match the layout instance,
+  which itself stays mounted across active-view switches inside
+  `/games/:id/*`.
 
-Phase 11 adds the per-game `GameStateStore` instance owned by this
+Phase 11 added the per-game `GameStateStore` instance owned by this
 layout: it constructs the `GalaxyClient`, fetches the matching lobby
 record to discover `current_turn`, then loads the report. The store
 is shared with descendants via `setContext("gameState", ...)` so the
-header turn counter, the map view, and later inspector tabs all read
+header turn counter, the map view, and the inspector tab all read
 from the same snapshot.
 
+Phase 13 adds the planet inspector. The layout watches the selection
+store and, on the null → planet transition, flips `activeTab` to
+`inspector` and `sidebarOpen` to `true` so the inspector becomes
+visible regardless of breakpoint (desktop already has the sidebar
+pinned; tablet needs the drawer to surface). On mobile the
+`<PlanetSheet />` overlay reads the same selection and displays a
+read-only sheet over the map; closing the sheet clears the
+selection.
+
 State preservation across active-view switches works for free
 because SvelteKit keeps this layout instance mounted while children
 swap; navigating between games unmounts and remounts the layout, so
-the next game's snapshot is loaded fresh.
+the next game's snapshot — and the next game's selection — start
+fresh.
 -->
 <script lang="ts">
 	import { onDestroy, onMount, setContext } from "svelte";
@@ -32,8 +50,13 @@ the next game's snapshot is loaded fresh.
 	import BottomTabs from "$lib/sidebar/bottom-tabs.svelte";
 	import Calculator from "$lib/sidebar/calculator-tab.svelte";
 	import Order from "$lib/sidebar/order-tab.svelte";
-	import type { MobileTool } from "$lib/sidebar/types";
+	import PlanetSheet from "$lib/inspectors/planet-sheet.svelte";
+	import type { MobileTool, SidebarTab } from "$lib/sidebar/types";
 	import { GameStateStore, GAME_STATE_CONTEXT_KEY } from "$lib/game-state.svelte";
+	import {
+		SelectionStore,
+		SELECTION_CONTEXT_KEY,
+	} from "$lib/selection.svelte";
 	import {
 		ORDER_DRAFT_CONTEXT_KEY,
 		OrderDraftStore,
@@ -49,6 +72,7 @@ the next game's snapshot is loaded fresh.
 
 	let sidebarOpen = $state(false);
 	let mobileTool: MobileTool = $state("map");
+	let activeTab: SidebarTab = $state("inspector");
 	// Phase 12 ships the prop wiring; Phase 26 replaces this constant
 	// with the real history-mode signal from `lib/history-mode.ts`.
 	const historyMode = false;
@@ -63,6 +87,33 @@ the next game's snapshot is loaded fresh.
 	setContext(GAME_STATE_CONTEXT_KEY, gameState);
 	const orderDraft = new OrderDraftStore();
 	setContext(ORDER_DRAFT_CONTEXT_KEY, orderDraft);
+	const selection = new SelectionStore();
+	setContext(SELECTION_CONTEXT_KEY, selection);
+
+	// selectedPlanet resolves the current selection against the live
+	// report so both the desktop sidebar and the mobile sheet display
+	// the same snapshot. A selection that points at a planet missing
+	// from the current report (e.g. visibility lost between turns)
+	// reads as `null` here, which collapses the inspector and the
+	// sheet without surfacing a stale row.
+	const selectedPlanet = $derived.by(() => {
+		const sel = selection.selected;
+		if (sel === null || sel.kind !== "planet") return null;
+		const report = gameState.report;
+		if (report === null) return null;
+		return report.planets.find((p) => p.number === sel.id) ?? null;
+	});
+
+	// Reveal the inspector whenever a new planet selection lands.
+	// Reading `selection.selected` once outside the effect keeps the
+	// effect dependent on the rune transition and not on the derived
+	// `selectedPlanet`, which can flicker as the report refreshes.
+	$effect(() => {
+		const sel = selection.selected;
+		if (sel === null) return;
+		activeTab = "inspector";
+		sidebarOpen = true;
+	});
 
 	function toggleSidebar(): void {
 		sidebarOpen = !sidebarOpen;
@@ -107,6 +158,7 @@ the next game's snapshot is loaded fresh.
 	onDestroy(() => {
 		gameState.dispose();
 		orderDraft.dispose();
+		selection.dispose();
 	});
 
 	function describeBootstrapError(err: unknown): string {
@@ -135,6 +187,7 @@ the next game's snapshot is loaded fresh.
 			open={sidebarOpen}
 			onClose={() => (sidebarOpen = false)}
 			{historyMode}
+			bind:activeTab
 		/>
 	</div>
 	<BottomTabs
@@ -143,6 +196,11 @@ the next game's snapshot is loaded fresh.
 		onSelectTool={(tool) => (mobileTool = tool)}
 		hideOrder={historyMode}
 	/>
+	<PlanetSheet
+		planet={selectedPlanet}
+		onMap={effectiveTool === "map"}
+		onClose={() => selection.clear()}
+	/>
 </div>
 
 <style>