diff --git a/ui/PLAN.md b/ui/PLAN.md
index 434921a..b5f33c5 100644
--- a/ui/PLAN.md
+++ b/ui/PLAN.md
@@ -1032,44 +1032,129 @@ Goal: assemble the in-game layout shell (header, sidebar, main area)
 with empty placeholder content for every view, so navigation works
 end-to-end before any data is wired.
 
-Artifacts:
+Decisions taken with the project owner during implementation:
 
-- `ui/frontend/src/routes/games/[id]/+layout.svelte` shell layout with
-  responsive breakpoints (desktop / tablet / mobile)
-- `ui/frontend/src/lib/header/` header component: race name, turn
-  counter (static placeholder `turn ?`), view dropdown / hamburger,
-  account menu
-- `ui/frontend/src/lib/sidebar/` sidebar with three tabs (Calculator,
-  Inspector, Order), each tab content stubbed to `coming soon`; mobile
-  bottom-tab bar `[Map, Calc, Order, More]` with corresponding stub
-  panels
-- `ui/frontend/src/lib/active-view/` view router supporting
-  `/games/:id/{map,table/:entity,report,battle/:battleId,mail,
-  designer/...}` with stub content per view
-- topic doc `ui/docs/navigation.md` documenting the active-view
-  model, the state-preservation rule, and the transient map-overlay
-  concept (the back-stack mechanism itself is implemented in Phase 34
-  when the first overlay user, ship-designer reach circles, ships)
+1. **Routing — file-system based, no extra dispatcher.** The
+   "view router" called out in the original artifact list is
+   implemented as SvelteKit's file-system routes plus thin
+   `+page.svelte` wrappers that mount the matching
+   `lib/active-view/<name>.svelte` stub. No separate dispatch
+   component lives in the codebase; each route file is a two-line
+   wrapper.
+2. **Optional designer ID segments.** Both designer URLs ship as
+   `[[id]]` optional segments
+   (`designer/ship-class/[[classId]]/`,
+   `designer/science/[[scienceId]]/`) so Phase 18 / 21 can read
+   the param without a routing migration. Phase 10 stubs ignore
+   the param.
+3. **Battle URL — optional id.** `battle/[[battleId]]/` accepts
+   both the list URL (`/battle`) and a specific battle URL
+   (`/battle/<id>`). Phase 27 keeps the optional segment and
+   switches behaviour based on presence.
+4. **Tablet sidebar — click toggle, not swipe.** The 768–1024 px
+   tablet sidebar slides in from a header-button click rather
+   than the IA section's swipe-from-right gesture. The structural
+   breakpoint switch satisfies Phase 10's acceptance criterion;
+   Phase 35 polish lands the swipe gesture.
+5. **Mobile tool overlay — `mobileTool` state, gated by URL.**
+   The mobile bottom-tabs Calc / Order navigate to `/map` and
+   set a layout-owned `mobileTool` rune. The layout's derived
+   `effectiveTool` only honours the rune when the URL is `/map`,
+   so navigating to any other view via the More drawer or the
+   header view-menu naturally drops the overlay. The desktop
+   sidebar separately accepts a `?sidebar=calc|inspector|order`
+   URL param that seeds the initial tab on first mount, used by
+   later phases that want to land directly on a particular tool.
+6. **Sidebar tool filenames — `*-tab.svelte`.** Phase 12 / 13 / 30
+   each name their final implementation
+   (`order-tab.svelte`, `inspector-tab.svelte`,
+   `calculator-tab.svelte`). The Phase 10 stubs ship with those
+   names so later phases replace the content in place without
+   renaming.
+7. **Race-name and turn-counter placeholders.** The header race
+   name is the static `race ?` string from i18n, mirroring the
+   spec's static `turn ?` placeholder. Phase 11 wires both from
+   `user.games.report` data through `lib/header/turn-counter.svelte`.
+8. **Auth gate inherited.** The root `+layout.svelte` already
+   redirects `anonymous → /login`; the in-game shell needs no
+   extra guard. Phase 10 verified this by booting the e2e shell
+   spec via `__galaxyDebug.setDeviceSessionId` and observing the
+   post-`session.init` `authenticated` status.
+9. **More drawer mirrors the view-menu.** The mobile bottom-tabs
+   "More" drawer renders the same seven destinations as the
+   header view-menu. The IA section's narrower More list (Mail,
+   Battle log, Tables, History, Settings, Logout) is the polish
+   target for Phase 35 once History exists; Phase 10 keeps a
+   single destination list to avoid drift.
+
+Artifacts (delivered):
+
+- `ui/frontend/src/routes/games/[id]/+layout.svelte` — chrome
+  layout (header, conditional sidebar, active-view slot, mobile
+  bottom-tabs, mobileTool gate, sidebarOpen toggle)
+- `ui/frontend/src/routes/games/[id]/+layout.ts` —
+  `ssr=false; prerender=false;` mirroring the root SPA flags
+- `ui/frontend/src/routes/games/[id]/+page.ts` — redirects
+  `/games/:id` → `/games/:id/map`
+- `ui/frontend/src/routes/games/[id]/{map, table/[entity], report,
+  battle/[[battleId]], mail, designer/ship-class/[[classId]],
+  designer/science/[[scienceId]]}/+page.svelte` — thin route
+  wrappers that mount the matching active-view stub
+- `ui/frontend/src/lib/header/{header, turn-counter, view-menu,
+  account-menu}.svelte` — header composition with race
+  placeholder, turn counter (static `?`), view-menu
+  (dropdown desktop / hamburger mobile), and account menu
+  (Settings / Sessions / Theme stub buttons; Language driven by
+  `i18n.setLocale`; Logout calls `session.signOut("user")`)
+- `ui/frontend/src/lib/sidebar/{sidebar, tab-bar, calculator-tab,
+  inspector-tab, order-tab, bottom-tabs}.svelte` — three-tab
+  sidebar with `inspector` default and `?sidebar=` URL seed;
+  mobile-only bottom-tabs with `[Map, Calc, Order, More]` plus a
+  More drawer duplicating the view-menu destinations
+- `ui/frontend/src/lib/sidebar/types.ts` — shared `SidebarTab`
+  and `MobileTool` types
+- `ui/frontend/src/lib/active-view/{map, table, report, battle,
+  mail, designer-ship-class, designer-science}.svelte` — Phase 10
+  stubs rendering localised titles plus `coming soon` copy with
+  stable testids that later phases replace
+- `ui/frontend/src/lib/i18n/locales/{en,ru}.ts` — full
+  `game.shell.*`, `game.view.*`, `game.sidebar.*`,
+  `game.bottom_tabs.*` catalogue
+- Topic doc `ui/docs/navigation.md`
+- Vitest: `tests/game-shell-{header,sidebar,stubs}.test.ts`
+- Playwright: `tests/e2e/game-shell.spec.ts` (7 cases × 4 projects;
+  mobile-only and viewport-switch cases conditionally skipped on
+  non-matching projects)
 
 Dependencies: Phase 8.
 
-Acceptance criteria:
+Acceptance criteria (met):
 
-- entering `/games/:id/map` from the lobby renders the shell with all
-  navigation chrome;
-- header dropdown switches to every other view; mobile hamburger does
-  the same;
+- entering `/games/:id/map` from the lobby renders the shell with
+  all navigation chrome;
+- header dropdown switches to every other view; mobile hamburger
+  does the same;
 - sidebar tabs preserve their stub state across switches;
 - the responsive layout matches the breakpoint diagrams in
-  `Information Architecture and Navigation`.
+  `Information Architecture and Navigation` (with the swipe
+  gesture deferred to Phase 35).
 
-Targeted tests:
+Targeted tests (delivered):
 
-- Vitest component tests for header navigation actions;
-- Playwright e2e: visit every view stub via header dropdown, assert
-  empty state copy renders;
-- multi-viewport Playwright run validating layout switches at the 768
-  px and 1024 px breakpoints.
+- Vitest component tests for the header (race / turn placeholders,
+  view-menu navigation to every IA destination, account-menu
+  Logout / Language wiring);
+- Vitest component tests for the sidebar (default tab, switching,
+  empty-state copy, `?sidebar=` URL seed, close button);
+- Vitest component tests for every active-view stub (title,
+  `coming soon` copy, table-entity prop, battle-id prop);
+- Playwright e2e: visit every view stub via header dropdown and
+  via the mobile More drawer; sidebar tab choice survives
+  navigation across active views; mobile bottom-tabs toggle the
+  Calc / Order tool overlay;
+- Playwright e2e: `setViewportSize`-driven viewport switch test
+  validates layout transitions at 768 px and 1024 px (sidebar
+  visibility, sidebar-toggle / bottom-tabs visibility).
 
 ## Phase 11. Map Wired to Live Game State
 
diff --git a/ui/docs/navigation.md b/ui/docs/navigation.md
new file mode 100644
index 0000000..fede5f1
--- /dev/null
+++ b/ui/docs/navigation.md
@@ -0,0 +1,127 @@
+# In-game shell — navigation model
+
+This doc covers the chrome that wraps every in-game view: the
+responsive layout shell, the active-view router built on SvelteKit's
+file-system routes, the sidebar with three tools and its
+state-preservation rule, and the mobile bottom-tabs. The user-facing
+spec — view list, breakpoint diagrams, history-mode plans — lives in
+[`../PLAN.md`](../PLAN.md), section
+`Information Architecture and Navigation`. This doc is the source of
+truth for how those rules are implemented.
+
+## Active-view model
+
+The client renders **one active view at a time**. Every active view is
+a SvelteKit route under `routes/games/[id]/`; the route file is a
+two-line wrapper that mounts the matching content component from
+`src/lib/active-view/<name>.svelte`. The "view router" mentioned in
+the plan is the file system plus those wrappers — there is no
+separate dispatch component.
+
+| URL                                   | Active view component                          | Phase that fills it     |
+| ------------------------------------- | ---------------------------------------------- | ----------------------- |
+| `/games/:id/map`                      | `lib/active-view/map.svelte`                   | Phase 11                |
+| `/games/:id/table/:entity`            | `lib/active-view/table.svelte`                 | Phase 11 / 17 / 19 / 22 |
+| `/games/:id/report`                   | `lib/active-view/report.svelte`                | Phase 23                |
+| `/games/:id/battle/:battleId?`        | `lib/active-view/battle.svelte`                | Phase 27                |
+| `/games/:id/mail`                     | `lib/active-view/mail.svelte`                  | Phase 28                |
+| `/games/:id/designer/ship-class/:id?` | `lib/active-view/designer-ship-class.svelte`   | Phase 17 / 18           |
+| `/games/:id/designer/science/:id?`    | `lib/active-view/designer-science.svelte`      | Phase 21                |
+
+`/games/:id` (no trailing view) redirects to `/games/:id/map`. The
+optional `:id?` segments on the designer routes match SvelteKit's
+`[[id]]` syntax — they accept both the new-draft and editing URLs;
+later phases read the param when wiring real content.
+
+The `entity` slug on the table route is kebab-case (`planets`,
+`ship-classes`, `ship-groups`, `fleets`, `sciences`, `races`); the
+table stub maps it to the matching `game.view.table.<snake>` i18n
+key.
+
+## Sidebar tools and state preservation
+
+The desktop sidebar hosts three tools:
+
+| Tool       | Component                              | Phase that fills it  |
+| ---------- | -------------------------------------- | -------------------- |
+| Calculator | `lib/sidebar/calculator-tab.svelte`    | Phase 30             |
+| Inspector  | `lib/sidebar/inspector-tab.svelte`     | Phase 13 / 19        |
+| Order      | `lib/sidebar/order-tab.svelte`         | Phase 12 / 14        |
+
+The sidebar's selected-tab state is a `$state` rune inside
+`lib/sidebar/sidebar.svelte`. The component is mounted by the layout
+at `routes/games/[id]/+layout.svelte`, and SvelteKit keeps that
+layout instance alive while the user navigates between child routes
+(`/games/:id/map` → `/games/:id/report` → …). The rune therefore
+survives every active-view switch automatically, with no URL coupling
+needed.
+
+A `?sidebar=calc|calculator|inspector|order` URL param is read once
+on mount and seeds the initial tab. Later phases that want to land
+the user on a particular tool (for example, Phase 14's first
+end-to-end command flow) can set it on navigation.
+
+## Layout breakpoints
+
+Three discrete CSS modes matched to the IA section diagrams:
+
+- **≥ 1024 px (desktop)** — the sidebar sits beside the active view
+  and is always rendered. The header view-menu trigger uses the
+  dropdown icon (▾). Bottom-tabs and the tablet sidebar-toggle are
+  CSS-hidden.
+- **768–1024 px (tablet)** — the sidebar collapses behind a click
+  toggle in the header right corner. Tapping the toggle slides the
+  sidebar in as a fixed overlay above the active view; a close
+  button on the sidebar dismisses it. The full swipe-from-right
+  gesture in the IA section is deferred to Phase 35 polish — the
+  click toggle satisfies the "layout switches at 768 px" acceptance
+  criterion on Phase 10.
+- **< 768 px (mobile)** — the sidebar is hidden entirely and the
+  bottom-tabs row appears at the bottom of the viewport. The
+  view-menu trigger swaps to a hamburger icon (☰) that opens the
+  drop-down as a full-width drawer below the header.
+
+Inspector is intentionally unreachable on mobile in Phase 10. Per the
+IA section the mobile inspector is a bottom-sheet raised by tapping a
+map object, and that mechanism waits for Phase 13.
+
+## Mobile bottom-tabs and tool overlay
+
+The bottom-tabs row is `[Map, Calc, Order, More]`. Map navigates to
+`/games/:id/map` and clears any tool overlay. Calc and Order navigate
+to `/games/:id/map` too — but they also flip the layout's
+`mobileTool` state to `calc` / `order`, which the layout uses to
+swap the active-view slot for the Calculator / Order tool component.
+
+The tool overlay only applies when the URL is `/map`. Navigating to
+any other view through the More drawer or the header view-menu makes
+the layout's derived `effectiveTool` collapse back to `map`, so the
+user always sees the URL's active view rather than a stale overlay.
+The next time the user taps a Calc or Order bottom-tab, the
+navigation re-routes them to `/map` and re-applies the overlay.
+
+The `More` button opens a drawer that mirrors the header view-menu
+content. The IA section's narrower "More" list (Mail, Battle log,
+Tables, History, Settings, Logout) is the polish target for Phase 35
+— Phase 10 keeps a single source of truth for destinations.
+
+## Transient map overlays
+
+Some views can push a transient overlay onto `/map` with a back
+affordance — for example, the ship-class designer pushes a
+range-preview overlay onto the map. The transient overlay clears
+when the user navigates to any other view via the header or the
+bottom-tabs.
+
+Phase 10 documents this concept but does not implement the
+back-stack mechanism. Phase 34 lands the back-stack alongside its
+first user (multi-turn projection, range circles in the ship-class
+designer).
+
+## Auth gate
+
+The root `+layout.svelte` redirects `anonymous → /login` for any
+non-`/__debug/` path; the in-game shell inherits that gate without
+any extra check. When a session is revoked while the user is in the
+shell, the same redirect fires through the existing
+revocation watcher.
diff --git a/ui/frontend/src/lib/active-view/battle.svelte b/ui/frontend/src/lib/active-view/battle.svelte
new file mode 100644
index 0000000..61480ba
--- /dev/null
+++ b/ui/frontend/src/lib/active-view/battle.svelte
@@ -0,0 +1,30 @@
+<!--
+Phase 10 stub for the battle-log active view. Phase 27 wires the real
+battle viewer.
+-->
+<script lang="ts">
+	import { i18n } from "$lib/i18n/index.svelte";
+
+	type Props = { battleId: string };
+	let { battleId }: Props = $props();
+</script>
+
+<section class="active-view" data-testid="active-view-battle" data-battle-id={battleId}>
+	<h2>{i18n.t("game.view.battle")}</h2>
+	<p>{i18n.t("game.shell.coming_soon")}</p>
+</section>
+
+<style>
+	.active-view {
+		padding: 1.5rem;
+		font-family: system-ui, sans-serif;
+	}
+	.active-view h2 {
+		margin: 0 0 0.5rem;
+		font-size: 1.1rem;
+	}
+	.active-view p {
+		margin: 0;
+		color: #555;
+	}
+</style>
diff --git a/ui/frontend/src/lib/active-view/designer-science.svelte b/ui/frontend/src/lib/active-view/designer-science.svelte
new file mode 100644
index 0000000..d5a7f05
--- /dev/null
+++ b/ui/frontend/src/lib/active-view/designer-science.svelte
@@ -0,0 +1,28 @@
+<!--
+Phase 10 stub for the science designer active view. Phase 21 wires
+the CRUD list and designer. The optional `scienceId` URL segment is
+accepted but ignored at this point.
+-->
+<script lang="ts">
+	import { i18n } from "$lib/i18n/index.svelte";
+</script>
+
+<section class="active-view" data-testid="active-view-designer-science">
+	<h2>{i18n.t("game.view.designer.science")}</h2>
+	<p>{i18n.t("game.shell.coming_soon")}</p>
+</section>
+
+<style>
+	.active-view {
+		padding: 1.5rem;
+		font-family: system-ui, sans-serif;
+	}
+	.active-view h2 {
+		margin: 0 0 0.5rem;
+		font-size: 1.1rem;
+	}
+	.active-view p {
+		margin: 0;
+		color: #555;
+	}
+</style>
diff --git a/ui/frontend/src/lib/active-view/designer-ship-class.svelte b/ui/frontend/src/lib/active-view/designer-ship-class.svelte
new file mode 100644
index 0000000..0dd5363
--- /dev/null
+++ b/ui/frontend/src/lib/active-view/designer-ship-class.svelte
@@ -0,0 +1,28 @@
+<!--
+Phase 10 stub for the ship-class designer active view. Phase 17 wires
+the CRUD list and Phase 18 the calc bridge. The optional `classId`
+URL segment is accepted but ignored at this point.
+-->
+<script lang="ts">
+	import { i18n } from "$lib/i18n/index.svelte";
+</script>
+
+<section class="active-view" data-testid="active-view-designer-ship-class">
+	<h2>{i18n.t("game.view.designer.ship_class")}</h2>
+	<p>{i18n.t("game.shell.coming_soon")}</p>
+</section>
+
+<style>
+	.active-view {
+		padding: 1.5rem;
+		font-family: system-ui, sans-serif;
+	}
+	.active-view h2 {
+		margin: 0 0 0.5rem;
+		font-size: 1.1rem;
+	}
+	.active-view p {
+		margin: 0;
+		color: #555;
+	}
+</style>
diff --git a/ui/frontend/src/lib/active-view/mail.svelte b/ui/frontend/src/lib/active-view/mail.svelte
new file mode 100644
index 0000000..2c1bb68
--- /dev/null
+++ b/ui/frontend/src/lib/active-view/mail.svelte
@@ -0,0 +1,27 @@
+<!--
+Phase 10 stub for the diplomatic-mail active view. Phase 28 wires the
+real mail listing.
+-->
+<script lang="ts">
+	import { i18n } from "$lib/i18n/index.svelte";
+</script>
+
+<section class="active-view" data-testid="active-view-mail">
+	<h2>{i18n.t("game.view.mail")}</h2>
+	<p>{i18n.t("game.shell.coming_soon")}</p>
+</section>
+
+<style>
+	.active-view {
+		padding: 1.5rem;
+		font-family: system-ui, sans-serif;
+	}
+	.active-view h2 {
+		margin: 0 0 0.5rem;
+		font-size: 1.1rem;
+	}
+	.active-view p {
+		margin: 0;
+		color: #555;
+	}
+</style>
diff --git a/ui/frontend/src/lib/active-view/map.svelte b/ui/frontend/src/lib/active-view/map.svelte
new file mode 100644
index 0000000..3fdbe8c
--- /dev/null
+++ b/ui/frontend/src/lib/active-view/map.svelte
@@ -0,0 +1,29 @@
+<!--
+Phase 10 stub for the map active view. Phase 11 swaps this for the
+live renderer integration described in `ui/PLAN.md` Phase 11. The
+stub keeps the same `data-testid` so Phase 11's spec replaces the
+copy assertion without touching navigation.
+-->
+<script lang="ts">
+	import { i18n } from "$lib/i18n/index.svelte";
+</script>
+
+<section class="active-view" data-testid="active-view-map">
+	<h2>{i18n.t("game.view.map")}</h2>
+	<p>{i18n.t("game.shell.coming_soon")}</p>
+</section>
+
+<style>
+	.active-view {
+		padding: 1.5rem;
+		font-family: system-ui, sans-serif;
+	}
+	.active-view h2 {
+		margin: 0 0 0.5rem;
+		font-size: 1.1rem;
+	}
+	.active-view p {
+		margin: 0;
+		color: #555;
+	}
+</style>
diff --git a/ui/frontend/src/lib/active-view/report.svelte b/ui/frontend/src/lib/active-view/report.svelte
new file mode 100644
index 0000000..35aba4e
--- /dev/null
+++ b/ui/frontend/src/lib/active-view/report.svelte
@@ -0,0 +1,28 @@
+<!--
+Phase 10 stub for the turn-report active view. Phase 23 replaces the
+body with the per-turn sections (cargo deliveries, completed sciences,
+mail, etc.).
+-->
+<script lang="ts">
+	import { i18n } from "$lib/i18n/index.svelte";
+</script>
+
+<section class="active-view" data-testid="active-view-report">
+	<h2>{i18n.t("game.view.report")}</h2>
+	<p>{i18n.t("game.shell.coming_soon")}</p>
+</section>
+
+<style>
+	.active-view {
+		padding: 1.5rem;
+		font-family: system-ui, sans-serif;
+	}
+	.active-view h2 {
+		margin: 0 0 0.5rem;
+		font-size: 1.1rem;
+	}
+	.active-view p {
+		margin: 0;
+		color: #555;
+	}
+</style>
diff --git a/ui/frontend/src/lib/active-view/table.svelte b/ui/frontend/src/lib/active-view/table.svelte
new file mode 100644
index 0000000..bd15827
--- /dev/null
+++ b/ui/frontend/src/lib/active-view/table.svelte
@@ -0,0 +1,39 @@
+<!--
+Phase 10 stub for the entity-table active view. Phase 11+ wires real
+list data per entity (planets in Phase 11, ship-classes in Phase 17,
+etc.). Until then, the stub renders the localised entity title plus a
+`coming soon` body so navigation can be exercised end-to-end.
+-->
+<script lang="ts">
+	import { i18n, type TranslationKey } from "$lib/i18n/index.svelte";
+
+	type Props = { entity: string };
+	let { entity }: Props = $props();
+
+	function entityKey(slug: string): TranslationKey {
+		const normalised = slug.replace(/-/g, "_");
+		return `game.view.table.${normalised}` as TranslationKey;
+	}
+</script>
+
+<section class="active-view" data-testid="active-view-table" data-entity={entity}>
+	<h2>
+		{i18n.t("game.view.table")}: {i18n.t(entityKey(entity))}
+	</h2>
+	<p>{i18n.t("game.shell.coming_soon")}</p>
+</section>
+
+<style>
+	.active-view {
+		padding: 1.5rem;
+		font-family: system-ui, sans-serif;
+	}
+	.active-view h2 {
+		margin: 0 0 0.5rem;
+		font-size: 1.1rem;
+	}
+	.active-view p {
+		margin: 0;
+		color: #555;
+	}
+</style>
diff --git a/ui/frontend/src/lib/header/account-menu.svelte b/ui/frontend/src/lib/header/account-menu.svelte
new file mode 100644
index 0000000..80bc601
--- /dev/null
+++ b/ui/frontend/src/lib/header/account-menu.svelte
@@ -0,0 +1,159 @@
+<!--
+Account-menu popover with Account / Settings / Sessions / Theme /
+Language / Logout. Phase 10 only wires Language (via the existing
+i18n primitive) and Logout (`session.signOut("user")`); the rest are
+stub buttons that later phases (35 polish, dedicated phases for
+Sessions and Theme) take over.
+-->
+<script lang="ts">
+	import { onMount } from "svelte";
+	import { i18n, SUPPORTED_LOCALES, type Locale } from "$lib/i18n/index.svelte";
+	import { session } from "$lib/session-store.svelte";
+
+	let open = $state(false);
+	let rootEl: HTMLDivElement | null = $state(null);
+
+	function toggleOpen(): void {
+		open = !open;
+	}
+
+	async function logout(): Promise<void> {
+		open = false;
+		await session.signOut("user");
+	}
+
+	function selectLocale(event: Event): void {
+		const value = (event.target as HTMLSelectElement).value as Locale;
+		i18n.setLocale(value);
+	}
+
+	function onKeyDown(event: KeyboardEvent): void {
+		if (event.key === "Escape" && open) {
+			open = false;
+		}
+	}
+
+	onMount(() => {
+		const handleClick = (event: MouseEvent): void => {
+			if (!open || rootEl === null) return;
+			const target = event.target;
+			if (target instanceof Node && rootEl.contains(target)) return;
+			open = false;
+		};
+		document.addEventListener("click", handleClick, true);
+		document.addEventListener("keydown", onKeyDown);
+		return () => {
+			document.removeEventListener("click", handleClick, true);
+			document.removeEventListener("keydown", onKeyDown);
+		};
+	});
+</script>
+
+<div class="account-menu" bind:this={rootEl}>
+	<button
+		type="button"
+		class="trigger"
+		data-testid="account-menu-trigger"
+		aria-haspopup="menu"
+		aria-expanded={open}
+		aria-label={i18n.t("game.shell.menu.account")}
+		onclick={toggleOpen}
+	>
+		⚙
+	</button>
+	{#if open}
+		<div class="surface" role="menu" data-testid="account-menu-list">
+			<button type="button" role="menuitem" data-testid="account-menu-settings" disabled>
+				{i18n.t("game.shell.menu.settings")}
+			</button>
+			<button type="button" role="menuitem" data-testid="account-menu-sessions" disabled>
+				{i18n.t("game.shell.menu.sessions")}
+			</button>
+			<button type="button" role="menuitem" data-testid="account-menu-theme" disabled>
+				{i18n.t("game.shell.menu.theme")}
+			</button>
+			<label class="locale" data-testid="account-menu-language">
+				<span>{i18n.t("game.shell.menu.language")}</span>
+				<select
+					data-testid="account-menu-language-select"
+					value={i18n.locale}
+					onchange={selectLocale}
+				>
+					{#each SUPPORTED_LOCALES as entry (entry.code)}
+						<option value={entry.code}>{entry.nativeName}</option>
+					{/each}
+				</select>
+			</label>
+			<button
+				type="button"
+				role="menuitem"
+				data-testid="account-menu-logout"
+				onclick={logout}
+			>
+				{i18n.t("game.shell.menu.logout")}
+			</button>
+		</div>
+	{/if}
+</div>
+
+<style>
+	.account-menu {
+		position: relative;
+	}
+	.trigger {
+		font: inherit;
+		font-size: 1.1rem;
+		padding: 0.25rem 0.6rem;
+		background: transparent;
+		color: inherit;
+		border: 1px solid #2a3150;
+		border-radius: 4px;
+		cursor: pointer;
+	}
+	.trigger:hover {
+		background: #1c2238;
+	}
+	.surface {
+		position: absolute;
+		top: calc(100% + 0.25rem);
+		right: 0;
+		min-width: 12rem;
+		display: flex;
+		flex-direction: column;
+		background: #14182a;
+		border: 1px solid #2a3150;
+		border-radius: 6px;
+		box-shadow: 0 6px 18px rgba(0, 0, 0, 0.4);
+		z-index: 50;
+	}
+	.surface > button,
+	.surface > label {
+		text-align: left;
+		font: inherit;
+		padding: 0.45rem 0.75rem;
+		background: transparent;
+		color: inherit;
+		border: 0;
+		cursor: pointer;
+	}
+	.surface > button:hover:not(:disabled) {
+		background: #1c2238;
+	}
+	.surface > button:disabled {
+		opacity: 0.5;
+		cursor: not-allowed;
+	}
+	.locale {
+		display: flex;
+		align-items: center;
+		gap: 0.5rem;
+	}
+	.locale select {
+		font: inherit;
+		background: #1c2238;
+		color: inherit;
+		border: 1px solid #2a3150;
+		border-radius: 4px;
+		padding: 0.15rem 0.35rem;
+	}
+</style>
diff --git a/ui/frontend/src/lib/header/header.svelte b/ui/frontend/src/lib/header/header.svelte
new file mode 100644
index 0000000..f85e64f
--- /dev/null
+++ b/ui/frontend/src/lib/header/header.svelte
@@ -0,0 +1,97 @@
+<!--
+Top header for the in-game shell. Composes the four artifacts called
+out by `ui/PLAN.md` Phase 10: race name (static placeholder), turn
+counter (static placeholder), view dropdown / hamburger, account
+menu. The sidebar-toggle slot to its left appears only on tablet
+viewports (768–1024 px) and is wired by `+layout.svelte`.
+
+The connection-state indicator from the IA section is intentionally
+absent until Phase 24 wires push-event state.
+-->
+<script lang="ts">
+	import { i18n } from "$lib/i18n/index.svelte";
+	import TurnCounter from "./turn-counter.svelte";
+	import ViewMenu from "./view-menu.svelte";
+	import AccountMenu from "./account-menu.svelte";
+
+	type Props = {
+		gameId: string;
+		sidebarOpen: boolean;
+		onToggleSidebar: () => void;
+	};
+	let { gameId, sidebarOpen, onToggleSidebar }: Props = $props();
+</script>
+
+<header class="game-shell-header" data-testid="game-shell-header">
+	<div class="left">
+		<span class="race" data-testid="race-name">
+			{i18n.t("game.shell.race_placeholder")}
+		</span>
+		<TurnCounter />
+	</div>
+	<div class="right">
+		<button
+			type="button"
+			class="sidebar-toggle"
+			data-testid="sidebar-toggle"
+			aria-expanded={sidebarOpen}
+			aria-label={sidebarOpen
+				? i18n.t("game.shell.menu.close_sidebar")
+				: i18n.t("game.shell.menu.toggle_sidebar")}
+			onclick={onToggleSidebar}
+		>
+			⤧
+		</button>
+		<ViewMenu {gameId} />
+		<AccountMenu />
+	</div>
+</header>
+
+<style>
+	.game-shell-header {
+		position: sticky;
+		top: 0;
+		z-index: 40;
+		display: flex;
+		justify-content: space-between;
+		align-items: center;
+		gap: 1rem;
+		padding: 0.5rem 0.75rem;
+		background: #0a0e1a;
+		color: #e8eaf6;
+		border-bottom: 1px solid #20253a;
+		font-family: system-ui, sans-serif;
+	}
+	.left,
+	.right {
+		display: flex;
+		align-items: center;
+		gap: 0.75rem;
+		min-width: 0;
+	}
+	.race {
+		font-weight: 500;
+		white-space: nowrap;
+		overflow: hidden;
+		text-overflow: ellipsis;
+	}
+	.sidebar-toggle {
+		font: inherit;
+		font-size: 1.1rem;
+		padding: 0.25rem 0.6rem;
+		background: transparent;
+		color: inherit;
+		border: 1px solid #2a3150;
+		border-radius: 4px;
+		cursor: pointer;
+		display: none;
+	}
+	.sidebar-toggle:hover {
+		background: #1c2238;
+	}
+	@media (min-width: 768px) and (max-width: 1023.98px) {
+		.sidebar-toggle {
+			display: inline-flex;
+		}
+	}
+</style>
diff --git a/ui/frontend/src/lib/header/turn-counter.svelte b/ui/frontend/src/lib/header/turn-counter.svelte
new file mode 100644
index 0000000..99e3570
--- /dev/null
+++ b/ui/frontend/src/lib/header/turn-counter.svelte
@@ -0,0 +1,21 @@
+<!--
+Phase 10 placeholder turn counter. The displayed value is the static
+`?` glyph from `game.shell.turn_unknown`; Phase 11 swaps the source
+to the live game state. The wrapping span is kept as the public
+shape so Phase 11 only needs to replace the inner text.
+-->
+<script lang="ts">
+	import { i18n } from "$lib/i18n/index.svelte";
+</script>
+
+<span class="turn" data-testid="turn-counter">
+	{i18n.t("game.shell.turn_label")}&nbsp;{i18n.t("game.shell.turn_unknown")}
+</span>
+
+<style>
+	.turn {
+		font-size: 0.95rem;
+		color: #ddd;
+		white-space: nowrap;
+	}
+</style>
diff --git a/ui/frontend/src/lib/header/view-menu.svelte b/ui/frontend/src/lib/header/view-menu.svelte
new file mode 100644
index 0000000..cbe5bd4
--- /dev/null
+++ b/ui/frontend/src/lib/header/view-menu.svelte
@@ -0,0 +1,254 @@
+<!--
+Active-view picker that drives navigation between every in-game view.
+The trigger swaps icon between desktop dropdown (▾) and mobile
+hamburger (☰) at the 1024 px breakpoint via CSS only; the surface
+itself is identical. The same component is reused for the mobile
+"More" drawer entry of `bottom-tabs.svelte`.
+
+Lists the seven IA destinations: map, tables (sub-list of six
+entities), report, battle, mail, ship-class designer, science
+designer. Closes on Escape, on outside click, and after a
+navigation. Phase 26 introduces the history-mode entry; Phase 35
+polishes microcopy.
+-->
+<script lang="ts">
+	import { onMount } from "svelte";
+	import { goto } from "$app/navigation";
+	import { i18n, type TranslationKey } from "$lib/i18n/index.svelte";
+
+	type Props = { gameId: string };
+	let { gameId }: Props = $props();
+
+	let open = $state(false);
+	let rootEl: HTMLDivElement | null = $state(null);
+
+	const tableEntities: ReadonlyArray<{ slug: string; key: TranslationKey }> = [
+		{ slug: "planets", key: "game.view.table.planets" },
+		{ slug: "ship-classes", key: "game.view.table.ship_classes" },
+		{ slug: "ship-groups", key: "game.view.table.ship_groups" },
+		{ slug: "fleets", key: "game.view.table.fleets" },
+		{ slug: "sciences", key: "game.view.table.sciences" },
+		{ slug: "races", key: "game.view.table.races" },
+	];
+
+	function toggleOpen(): void {
+		open = !open;
+	}
+
+	function go(path: string): void {
+		open = false;
+		void goto(path);
+	}
+
+	function onKeyDown(event: KeyboardEvent): void {
+		if (event.key === "Escape" && open) {
+			open = false;
+		}
+	}
+
+	onMount(() => {
+		const handleClick = (event: MouseEvent): void => {
+			if (!open || rootEl === null) return;
+			const target = event.target;
+			if (target instanceof Node && rootEl.contains(target)) return;
+			open = false;
+		};
+		document.addEventListener("click", handleClick, true);
+		document.addEventListener("keydown", onKeyDown);
+		return () => {
+			document.removeEventListener("click", handleClick, true);
+			document.removeEventListener("keydown", onKeyDown);
+		};
+	});
+</script>
+
+<div class="view-menu" bind:this={rootEl}>
+	<button
+		type="button"
+		class="trigger"
+		data-testid="view-menu-trigger"
+		aria-haspopup="menu"
+		aria-expanded={open}
+		aria-label={open
+			? i18n.t("game.shell.menu.close_views")
+			: i18n.t("game.shell.menu.open_views")}
+		onclick={toggleOpen}
+	>
+		<span class="icon-dropdown" aria-hidden="true">▾</span>
+		<span class="icon-hamburger" aria-hidden="true">☰</span>
+	</button>
+	{#if open}
+		<div class="surface" role="menu" data-testid="view-menu-list">
+			<button
+				type="button"
+				role="menuitem"
+				data-testid="view-menu-item-map"
+				onclick={() => go(`/games/${gameId}/map`)}
+			>
+				{i18n.t("game.view.map")}
+			</button>
+			<details data-testid="view-menu-tables">
+				<summary>{i18n.t("game.view.table")}</summary>
+				<div class="sub">
+					{#each tableEntities as entry (entry.slug)}
+						<button
+							type="button"
+							role="menuitem"
+							data-testid="view-menu-item-table-{entry.slug}"
+							onclick={() => go(`/games/${gameId}/table/${entry.slug}`)}
+						>
+							{i18n.t(entry.key)}
+						</button>
+					{/each}
+				</div>
+			</details>
+			<button
+				type="button"
+				role="menuitem"
+				data-testid="view-menu-item-report"
+				onclick={() => go(`/games/${gameId}/report`)}
+			>
+				{i18n.t("game.view.report")}
+			</button>
+			<button
+				type="button"
+				role="menuitem"
+				data-testid="view-menu-item-battle"
+				onclick={() => go(`/games/${gameId}/battle`)}
+			>
+				{i18n.t("game.view.battle")}
+			</button>
+			<button
+				type="button"
+				role="menuitem"
+				data-testid="view-menu-item-mail"
+				onclick={() => go(`/games/${gameId}/mail`)}
+			>
+				{i18n.t("game.view.mail")}
+			</button>
+			<button
+				type="button"
+				role="menuitem"
+				data-testid="view-menu-item-designer-ship-class"
+				onclick={() => go(`/games/${gameId}/designer/ship-class`)}
+			>
+				{i18n.t("game.view.designer.ship_class")}
+			</button>
+			<button
+				type="button"
+				role="menuitem"
+				data-testid="view-menu-item-designer-science"
+				onclick={() => go(`/games/${gameId}/designer/science`)}
+			>
+				{i18n.t("game.view.designer.science")}
+			</button>
+		</div>
+	{/if}
+</div>
+
+<style>
+	.view-menu {
+		position: relative;
+	}
+	.trigger {
+		font: inherit;
+		font-size: 1.1rem;
+		padding: 0.25rem 0.6rem;
+		background: transparent;
+		color: inherit;
+		border: 1px solid #2a3150;
+		border-radius: 4px;
+		cursor: pointer;
+	}
+	.trigger:hover {
+		background: #1c2238;
+	}
+	.icon-dropdown {
+		display: inline;
+	}
+	.icon-hamburger {
+		display: none;
+	}
+	@media (max-width: 767.98px) {
+		.icon-dropdown {
+			display: none;
+		}
+		.icon-hamburger {
+			display: inline;
+		}
+	}
+	.surface {
+		position: absolute;
+		top: calc(100% + 0.25rem);
+		right: 0;
+		min-width: 14rem;
+		display: flex;
+		flex-direction: column;
+		background: #14182a;
+		border: 1px solid #2a3150;
+		border-radius: 6px;
+		box-shadow: 0 6px 18px rgba(0, 0, 0, 0.4);
+		z-index: 50;
+	}
+	.surface > button,
+	.surface > details > summary {
+		text-align: left;
+		font: inherit;
+		padding: 0.45rem 0.75rem;
+		background: transparent;
+		color: inherit;
+		border: 0;
+		cursor: pointer;
+	}
+	.surface > button:hover,
+	.surface > details > summary:hover {
+		background: #1c2238;
+	}
+	.surface > details > summary {
+		list-style: none;
+	}
+	.surface > details > summary::-webkit-details-marker {
+		display: none;
+	}
+	.surface > details > summary::after {
+		content: "▸";
+		float: right;
+		opacity: 0.7;
+	}
+	.surface > details[open] > summary::after {
+		content: "▾";
+	}
+	.sub {
+		display: flex;
+		flex-direction: column;
+		padding-left: 0.5rem;
+		border-left: 1px solid #2a3150;
+		margin: 0 0.5rem 0.25rem;
+	}
+	.sub > button {
+		text-align: left;
+		font: inherit;
+		padding: 0.35rem 0.5rem;
+		background: transparent;
+		color: inherit;
+		border: 0;
+		cursor: pointer;
+	}
+	.sub > button:hover {
+		background: #1c2238;
+	}
+	@media (max-width: 767.98px) {
+		.surface {
+			position: fixed;
+			top: 3rem;
+			right: 0;
+			left: 0;
+			min-width: 0;
+			border-radius: 0;
+			border-left: 0;
+			border-right: 0;
+			max-height: calc(100vh - 3rem);
+			overflow-y: auto;
+		}
+	}
+</style>
diff --git a/ui/frontend/src/lib/i18n/locales/en.ts b/ui/frontend/src/lib/i18n/locales/en.ts
index e68cb4b..48207f7 100644
--- a/ui/frontend/src/lib/i18n/locales/en.ts
+++ b/ui/frontend/src/lib/i18n/locales/en.ts
@@ -82,6 +82,47 @@ const en = {
 	"lobby.error.conflict": "request conflicts with current state",
 	"lobby.error.internal_error": "internal server error",
 	"lobby.error.unknown": "{message}",
+
+	"game.shell.race_placeholder": "race ?",
+	"game.shell.turn_label": "turn",
+	"game.shell.turn_unknown": "?",
+	"game.shell.connection.online": "online",
+	"game.shell.connection.reconnecting": "reconnecting…",
+	"game.shell.connection.offline": "offline",
+	"game.shell.menu.toggle_sidebar": "open sidebar",
+	"game.shell.menu.close_sidebar": "close sidebar",
+	"game.shell.menu.open_views": "open views menu",
+	"game.shell.menu.close_views": "close views menu",
+	"game.shell.menu.account": "account",
+	"game.shell.menu.settings": "settings",
+	"game.shell.menu.sessions": "sessions",
+	"game.shell.menu.theme": "theme",
+	"game.shell.menu.language": "language",
+	"game.shell.menu.logout": "logout",
+	"game.shell.coming_soon": "coming soon",
+	"game.view.map": "map",
+	"game.view.table": "table",
+	"game.view.table.planets": "planets",
+	"game.view.table.ship_classes": "ship classes",
+	"game.view.table.ship_groups": "ship groups",
+	"game.view.table.fleets": "fleets",
+	"game.view.table.sciences": "sciences",
+	"game.view.table.races": "races",
+	"game.view.report": "turn report",
+	"game.view.battle": "battle log",
+	"game.view.mail": "diplomatic mail",
+	"game.view.designer.ship_class": "ship-class designer",
+	"game.view.designer.science": "science designer",
+	"game.sidebar.tab.calculator": "calculator",
+	"game.sidebar.tab.inspector": "inspector",
+	"game.sidebar.tab.order": "order",
+	"game.sidebar.empty.calculator": "coming soon",
+	"game.sidebar.empty.inspector": "select an object on the map",
+	"game.sidebar.empty.order": "coming soon",
+	"game.bottom_tabs.map": "map",
+	"game.bottom_tabs.calc": "calc",
+	"game.bottom_tabs.order": "order",
+	"game.bottom_tabs.more": "more",
 } as const;
 
 export default en;
diff --git a/ui/frontend/src/lib/i18n/locales/ru.ts b/ui/frontend/src/lib/i18n/locales/ru.ts
index c67b181..5199364 100644
--- a/ui/frontend/src/lib/i18n/locales/ru.ts
+++ b/ui/frontend/src/lib/i18n/locales/ru.ts
@@ -83,6 +83,47 @@ const ru: Record<keyof typeof en, string> = {
 	"lobby.error.conflict": "запрос конфликтует с текущим состоянием",
 	"lobby.error.internal_error": "внутренняя ошибка сервера",
 	"lobby.error.unknown": "{message}",
+
+	"game.shell.race_placeholder": "раса ?",
+	"game.shell.turn_label": "ход",
+	"game.shell.turn_unknown": "?",
+	"game.shell.connection.online": "онлайн",
+	"game.shell.connection.reconnecting": "переподключение…",
+	"game.shell.connection.offline": "офлайн",
+	"game.shell.menu.toggle_sidebar": "открыть боковую панель",
+	"game.shell.menu.close_sidebar": "закрыть боковую панель",
+	"game.shell.menu.open_views": "открыть меню видов",
+	"game.shell.menu.close_views": "закрыть меню видов",
+	"game.shell.menu.account": "аккаунт",
+	"game.shell.menu.settings": "настройки",
+	"game.shell.menu.sessions": "сессии",
+	"game.shell.menu.theme": "тема",
+	"game.shell.menu.language": "язык",
+	"game.shell.menu.logout": "выйти",
+	"game.shell.coming_soon": "скоро будет",
+	"game.view.map": "карта",
+	"game.view.table": "таблица",
+	"game.view.table.planets": "планеты",
+	"game.view.table.ship_classes": "классы кораблей",
+	"game.view.table.ship_groups": "группы кораблей",
+	"game.view.table.fleets": "флоты",
+	"game.view.table.sciences": "науки",
+	"game.view.table.races": "расы",
+	"game.view.report": "отчёт хода",
+	"game.view.battle": "журнал боёв",
+	"game.view.mail": "дипломатическая почта",
+	"game.view.designer.ship_class": "конструктор класса кораблей",
+	"game.view.designer.science": "редактор наук",
+	"game.sidebar.tab.calculator": "калькулятор",
+	"game.sidebar.tab.inspector": "инспектор",
+	"game.sidebar.tab.order": "приказ",
+	"game.sidebar.empty.calculator": "скоро будет",
+	"game.sidebar.empty.inspector": "выберите объект на карте",
+	"game.sidebar.empty.order": "скоро будет",
+	"game.bottom_tabs.map": "карта",
+	"game.bottom_tabs.calc": "калк",
+	"game.bottom_tabs.order": "приказ",
+	"game.bottom_tabs.more": "ещё",
 };
 
 export default ru;
diff --git a/ui/frontend/src/lib/sidebar/bottom-tabs.svelte b/ui/frontend/src/lib/sidebar/bottom-tabs.svelte
new file mode 100644
index 0000000..2b4febb
--- /dev/null
+++ b/ui/frontend/src/lib/sidebar/bottom-tabs.svelte
@@ -0,0 +1,297 @@
+<!--
+Mobile-only bottom-tab bar `[Map, Calc, Order, More]`. Map navigates
+to `/games/:id/map` and resets the tool overlay. Calc and Order also
+navigate to `/games/:id/map` — the layout's tool gate replaces the
+active view with the matching sidebar tool only when the URL is
+`/map`, so navigating to any other view via the More drawer or the
+header view-menu naturally drops the overlay.
+
+More opens a drawer with the same destination list as the header
+view-menu. Phase 35 polish narrows it to the IA-spec subset
+(Mail, Battle log, Tables, History, Settings, Logout) once History
+exists; until then the convenience of one source of truth for
+destinations beats the duplication.
+-->
+<script lang="ts">
+	import { onMount } from "svelte";
+	import { goto } from "$app/navigation";
+	import { i18n, type TranslationKey } from "$lib/i18n/index.svelte";
+	import type { MobileTool } from "./types";
+
+	type Props = {
+		gameId: string;
+		activeTool: MobileTool;
+		onSelectTool: (tool: MobileTool) => void;
+	};
+	let { gameId, activeTool, onSelectTool }: Props = $props();
+
+	let moreOpen = $state(false);
+	let rootEl: HTMLDivElement | null = $state(null);
+
+	const tableEntities: ReadonlyArray<{ slug: string; key: TranslationKey }> = [
+		{ slug: "planets", key: "game.view.table.planets" },
+		{ slug: "ship-classes", key: "game.view.table.ship_classes" },
+		{ slug: "ship-groups", key: "game.view.table.ship_groups" },
+		{ slug: "fleets", key: "game.view.table.fleets" },
+		{ slug: "sciences", key: "game.view.table.sciences" },
+		{ slug: "races", key: "game.view.table.races" },
+	];
+
+	async function selectTool(tool: MobileTool): Promise<void> {
+		moreOpen = false;
+		onSelectTool(tool);
+		await goto(`/games/${gameId}/map`);
+	}
+
+	async function go(path: string): Promise<void> {
+		moreOpen = false;
+		onSelectTool("map");
+		await goto(path);
+	}
+
+	function toggleMore(): void {
+		moreOpen = !moreOpen;
+	}
+
+	function onKeyDown(event: KeyboardEvent): void {
+		if (event.key === "Escape" && moreOpen) {
+			moreOpen = false;
+		}
+	}
+
+	onMount(() => {
+		const handleClick = (event: MouseEvent): void => {
+			if (!moreOpen || rootEl === null) return;
+			const target = event.target;
+			if (target instanceof Node && rootEl.contains(target)) return;
+			moreOpen = false;
+		};
+		document.addEventListener("click", handleClick, true);
+		document.addEventListener("keydown", onKeyDown);
+		return () => {
+			document.removeEventListener("click", handleClick, true);
+			document.removeEventListener("keydown", onKeyDown);
+		};
+	});
+</script>
+
+<div class="bottom-tabs" data-testid="bottom-tabs" bind:this={rootEl}>
+	<div class="tabs" role="tablist" aria-label={i18n.t("game.bottom_tabs.map")}>
+		<button
+			type="button"
+			role="tab"
+			data-testid="bottom-tab-map"
+			aria-selected={activeTool === "map"}
+			class:active={activeTool === "map"}
+			onclick={() => selectTool("map")}
+		>
+			<span class="icon" aria-hidden="true">▣</span>
+			<span class="label">{i18n.t("game.bottom_tabs.map")}</span>
+		</button>
+		<button
+			type="button"
+			role="tab"
+			data-testid="bottom-tab-calc"
+			aria-selected={activeTool === "calc"}
+			class:active={activeTool === "calc"}
+			onclick={() => selectTool("calc")}
+		>
+			<span class="icon" aria-hidden="true">🧮</span>
+			<span class="label">{i18n.t("game.bottom_tabs.calc")}</span>
+		</button>
+		<button
+			type="button"
+			role="tab"
+			data-testid="bottom-tab-order"
+			aria-selected={activeTool === "order"}
+			class:active={activeTool === "order"}
+			onclick={() => selectTool("order")}
+		>
+			<span class="icon" aria-hidden="true">📝</span>
+			<span class="label">{i18n.t("game.bottom_tabs.order")}</span>
+		</button>
+		<button
+			type="button"
+			data-testid="bottom-tab-more"
+			aria-haspopup="menu"
+			aria-expanded={moreOpen}
+			class:active={moreOpen}
+			onclick={toggleMore}
+		>
+			<span class="icon" aria-hidden="true">☰</span>
+			<span class="label">{i18n.t("game.bottom_tabs.more")}</span>
+		</button>
+	</div>
+	{#if moreOpen}
+		<div class="drawer" role="menu" data-testid="bottom-tabs-more-drawer">
+			<button
+				type="button"
+				role="menuitem"
+				data-testid="bottom-tabs-more-map"
+				onclick={() => go(`/games/${gameId}/map`)}
+			>
+				{i18n.t("game.view.map")}
+			</button>
+			<details data-testid="bottom-tabs-more-tables">
+				<summary>{i18n.t("game.view.table")}</summary>
+				<div class="sub">
+					{#each tableEntities as entry (entry.slug)}
+						<button
+							type="button"
+							role="menuitem"
+							data-testid="bottom-tabs-more-table-{entry.slug}"
+							onclick={() => go(`/games/${gameId}/table/${entry.slug}`)}
+						>
+							{i18n.t(entry.key)}
+						</button>
+					{/each}
+				</div>
+			</details>
+			<button
+				type="button"
+				role="menuitem"
+				data-testid="bottom-tabs-more-report"
+				onclick={() => go(`/games/${gameId}/report`)}
+			>
+				{i18n.t("game.view.report")}
+			</button>
+			<button
+				type="button"
+				role="menuitem"
+				data-testid="bottom-tabs-more-battle"
+				onclick={() => go(`/games/${gameId}/battle`)}
+			>
+				{i18n.t("game.view.battle")}
+			</button>
+			<button
+				type="button"
+				role="menuitem"
+				data-testid="bottom-tabs-more-mail"
+				onclick={() => go(`/games/${gameId}/mail`)}
+			>
+				{i18n.t("game.view.mail")}
+			</button>
+			<button
+				type="button"
+				role="menuitem"
+				data-testid="bottom-tabs-more-designer-ship-class"
+				onclick={() => go(`/games/${gameId}/designer/ship-class`)}
+			>
+				{i18n.t("game.view.designer.ship_class")}
+			</button>
+			<button
+				type="button"
+				role="menuitem"
+				data-testid="bottom-tabs-more-designer-science"
+				onclick={() => go(`/games/${gameId}/designer/science`)}
+			>
+				{i18n.t("game.view.designer.science")}
+			</button>
+		</div>
+	{/if}
+</div>
+
+<style>
+	.bottom-tabs {
+		display: none;
+		position: relative;
+	}
+	@media (max-width: 767.98px) {
+		.bottom-tabs {
+			display: block;
+		}
+	}
+	.tabs {
+		display: flex;
+		justify-content: space-around;
+		align-items: stretch;
+		background: #0a0e1a;
+		color: #e8eaf6;
+		border-top: 1px solid #20253a;
+		font-family: system-ui, sans-serif;
+	}
+	.tabs button {
+		flex: 1;
+		display: flex;
+		flex-direction: column;
+		align-items: center;
+		gap: 0.15rem;
+		padding: 0.4rem 0.25rem;
+		font: inherit;
+		font-size: 0.75rem;
+		background: transparent;
+		color: #aab;
+		border: 0;
+		cursor: pointer;
+	}
+	.tabs button.active {
+		color: #e8eaf6;
+		background: #1c2238;
+	}
+	.tabs .icon {
+		font-size: 1.25rem;
+	}
+	.drawer {
+		position: fixed;
+		left: 0;
+		right: 0;
+		bottom: 3.25rem;
+		max-height: calc(100vh - 6rem);
+		overflow-y: auto;
+		display: flex;
+		flex-direction: column;
+		background: #14182a;
+		color: #e8eaf6;
+		border-top: 1px solid #2a3150;
+		box-shadow: 0 -8px 24px rgba(0, 0, 0, 0.4);
+		z-index: 50;
+		font-family: system-ui, sans-serif;
+	}
+	.drawer > button,
+	.drawer > details > summary {
+		text-align: left;
+		font: inherit;
+		padding: 0.55rem 0.9rem;
+		background: transparent;
+		color: inherit;
+		border: 0;
+		cursor: pointer;
+	}
+	.drawer > button:hover,
+	.drawer > details > summary:hover {
+		background: #1c2238;
+	}
+	.drawer > details > summary {
+		list-style: none;
+	}
+	.drawer > details > summary::-webkit-details-marker {
+		display: none;
+	}
+	.drawer > details > summary::after {
+		content: "▸";
+		float: right;
+		opacity: 0.7;
+	}
+	.drawer > details[open] > summary::after {
+		content: "▾";
+	}
+	.sub {
+		display: flex;
+		flex-direction: column;
+		padding-left: 0.5rem;
+		border-left: 1px solid #2a3150;
+		margin: 0 0.5rem 0.25rem;
+	}
+	.sub > button {
+		text-align: left;
+		font: inherit;
+		padding: 0.4rem 0.5rem;
+		background: transparent;
+		color: inherit;
+		border: 0;
+		cursor: pointer;
+	}
+	.sub > button:hover {
+		background: #1c2238;
+	}
+</style>
diff --git a/ui/frontend/src/lib/sidebar/calculator-tab.svelte b/ui/frontend/src/lib/sidebar/calculator-tab.svelte
new file mode 100644
index 0000000..cd5fe88
--- /dev/null
+++ b/ui/frontend/src/lib/sidebar/calculator-tab.svelte
@@ -0,0 +1,29 @@
+<!--
+Phase 10 stub for the Calculator sidebar tool. Phase 30 wires the
+real ship/path calculator. Until then the stub renders a localised
+`coming soon` paragraph with a stable testid that later phases can
+replace without touching navigation.
+-->
+<script lang="ts">
+	import { i18n } from "$lib/i18n/index.svelte";
+</script>
+
+<section class="tool" data-testid="sidebar-tool-calculator">
+	<h3>{i18n.t("game.sidebar.tab.calculator")}</h3>
+	<p>{i18n.t("game.sidebar.empty.calculator")}</p>
+</section>
+
+<style>
+	.tool {
+		padding: 1rem;
+		font-family: system-ui, sans-serif;
+	}
+	.tool h3 {
+		margin: 0 0 0.5rem;
+		font-size: 1rem;
+	}
+	.tool p {
+		margin: 0;
+		color: #888;
+	}
+</style>
diff --git a/ui/frontend/src/lib/sidebar/inspector-tab.svelte b/ui/frontend/src/lib/sidebar/inspector-tab.svelte
new file mode 100644
index 0000000..f505278
--- /dev/null
+++ b/ui/frontend/src/lib/sidebar/inspector-tab.svelte
@@ -0,0 +1,29 @@
+<!--
+Phase 10 stub for the Inspector sidebar tool. The empty-state copy
+matches the IA section verbatim — `select an object on the map` —
+so the user understands the intended interaction before Phase 13
+wires real planet selection.
+-->
+<script lang="ts">
+	import { i18n } from "$lib/i18n/index.svelte";
+</script>
+
+<section class="tool" data-testid="sidebar-tool-inspector">
+	<h3>{i18n.t("game.sidebar.tab.inspector")}</h3>
+	<p>{i18n.t("game.sidebar.empty.inspector")}</p>
+</section>
+
+<style>
+	.tool {
+		padding: 1rem;
+		font-family: system-ui, sans-serif;
+	}
+	.tool h3 {
+		margin: 0 0 0.5rem;
+		font-size: 1rem;
+	}
+	.tool p {
+		margin: 0;
+		color: #888;
+	}
+</style>
diff --git a/ui/frontend/src/lib/sidebar/order-tab.svelte b/ui/frontend/src/lib/sidebar/order-tab.svelte
new file mode 100644
index 0000000..df6bf64
--- /dev/null
+++ b/ui/frontend/src/lib/sidebar/order-tab.svelte
@@ -0,0 +1,27 @@
+<!--
+Phase 10 stub for the Order composer sidebar tool. Phase 12 ships
+the composer skeleton; Phase 14 lands the first end-to-end command.
+-->
+<script lang="ts">
+	import { i18n } from "$lib/i18n/index.svelte";
+</script>
+
+<section class="tool" data-testid="sidebar-tool-order">
+	<h3>{i18n.t("game.sidebar.tab.order")}</h3>
+	<p>{i18n.t("game.sidebar.empty.order")}</p>
+</section>
+
+<style>
+	.tool {
+		padding: 1rem;
+		font-family: system-ui, sans-serif;
+	}
+	.tool h3 {
+		margin: 0 0 0.5rem;
+		font-size: 1rem;
+	}
+	.tool p {
+		margin: 0;
+		color: #888;
+	}
+</style>
diff --git a/ui/frontend/src/lib/sidebar/sidebar.svelte b/ui/frontend/src/lib/sidebar/sidebar.svelte
new file mode 100644
index 0000000..a8796e6
--- /dev/null
+++ b/ui/frontend/src/lib/sidebar/sidebar.svelte
@@ -0,0 +1,130 @@
+<!--
+Phase 10 sidebar with three tabs (Calculator, Inspector, Order). The
+parent layout decides whether the sidebar is rendered at all (mobile
+hides it, tablet collapses it behind the header toggle, desktop
+keeps it always visible). State preservation across active-view
+switches works for free because the layout never remounts when the
+user navigates within `/games/:id/*`.
+
+The optional `?sidebar=calc|calculator|inspector|order` URL param
+seeds the initial tab on first mount — used by the lobby card path
+when later phases want to land directly on a particular tool.
+-->
+<script lang="ts">
+	import { onMount } from "svelte";
+	import { page } from "$app/state";
+	import TabBar from "./tab-bar.svelte";
+	import Calculator from "./calculator-tab.svelte";
+	import Inspector from "./inspector-tab.svelte";
+	import Order from "./order-tab.svelte";
+	import type { SidebarTab } from "./types";
+	import { i18n } from "$lib/i18n/index.svelte";
+
+	type Props = {
+		open: boolean;
+		onClose: () => void;
+	};
+	let { open, onClose }: Props = $props();
+
+	let activeTab: SidebarTab = $state("inspector");
+
+	function readUrlSeed(): SidebarTab | null {
+		const v = page.url.searchParams.get("sidebar");
+		if (v === "calc" || v === "calculator") return "calculator";
+		if (v === "inspector") return "inspector";
+		if (v === "order") return "order";
+		return null;
+	}
+
+	onMount(() => {
+		const seed = readUrlSeed();
+		if (seed !== null) {
+			activeTab = seed;
+		}
+	});
+</script>
+
+<aside
+	class="sidebar"
+	data-testid="sidebar"
+	data-active-tab={activeTab}
+	data-open={open}
+>
+	<div class="head">
+		<TabBar {activeTab} onSelect={(tab) => (activeTab = tab)} />
+		<button
+			type="button"
+			class="close"
+			data-testid="sidebar-close"
+			aria-label={i18n.t("game.shell.menu.close_sidebar")}
+			onclick={onClose}
+		>
+			✕
+		</button>
+	</div>
+	<div class="content" data-testid="sidebar-content">
+		{#if activeTab === "calculator"}
+			<Calculator />
+		{:else if activeTab === "inspector"}
+			<Inspector />
+		{:else}
+			<Order />
+		{/if}
+	</div>
+</aside>
+
+<style>
+	.sidebar {
+		display: flex;
+		flex-direction: column;
+		width: 18rem;
+		min-width: 18rem;
+		background: #0e1322;
+		color: #e8eaf6;
+		border-left: 1px solid #20253a;
+	}
+	.head {
+		display: flex;
+		align-items: center;
+		justify-content: space-between;
+		gap: 0.5rem;
+	}
+	.close {
+		display: none;
+		font: inherit;
+		font-size: 1rem;
+		padding: 0.25rem 0.5rem;
+		margin-right: 0.5rem;
+		background: transparent;
+		color: inherit;
+		border: 0;
+		cursor: pointer;
+	}
+	.close:hover {
+		color: #6d8cff;
+	}
+	.content {
+		flex: 1;
+		overflow-y: auto;
+	}
+	@media (max-width: 1023.98px) {
+		.sidebar {
+			display: none;
+		}
+	}
+	@media (min-width: 768px) and (max-width: 1023.98px) {
+		.sidebar[data-open="true"] {
+			display: flex;
+			position: fixed;
+			top: 3rem;
+			right: 0;
+			bottom: 0;
+			width: min(20rem, 80vw);
+			z-index: 30;
+			box-shadow: -8px 0 24px rgba(0, 0, 0, 0.4);
+		}
+		.sidebar[data-open="true"] .close {
+			display: inline-flex;
+		}
+	}
+</style>
diff --git a/ui/frontend/src/lib/sidebar/tab-bar.svelte b/ui/frontend/src/lib/sidebar/tab-bar.svelte
new file mode 100644
index 0000000..f95ca3d
--- /dev/null
+++ b/ui/frontend/src/lib/sidebar/tab-bar.svelte
@@ -0,0 +1,64 @@
+<!--
+Three-button tab switcher for the Phase 10 sidebar. Each button is
+labelled and tagged so component tests can target it; the parent
+sidebar component owns the selected-tab state and re-renders the
+matching tool panel.
+-->
+<script lang="ts">
+	import { i18n, type TranslationKey } from "$lib/i18n/index.svelte";
+	import type { SidebarTab } from "./types";
+
+	type Props = {
+		activeTab: SidebarTab;
+		onSelect: (tab: SidebarTab) => void;
+	};
+	let { activeTab, onSelect }: Props = $props();
+
+	const tabs: ReadonlyArray<{ id: SidebarTab; key: TranslationKey }> = [
+		{ id: "calculator", key: "game.sidebar.tab.calculator" },
+		{ id: "inspector", key: "game.sidebar.tab.inspector" },
+		{ id: "order", key: "game.sidebar.tab.order" },
+	];
+</script>
+
+<div class="tab-bar" role="tablist" data-testid="sidebar-tab-bar">
+	{#each tabs as tab (tab.id)}
+		<button
+			type="button"
+			role="tab"
+			data-testid="sidebar-tab-{tab.id}"
+			aria-selected={tab.id === activeTab}
+			class:active={tab.id === activeTab}
+			onclick={() => onSelect(tab.id)}
+		>
+			{i18n.t(tab.key)}
+		</button>
+	{/each}
+</div>
+
+<style>
+	.tab-bar {
+		display: flex;
+		gap: 0.25rem;
+		padding: 0.5rem 0.5rem 0;
+		border-bottom: 1px solid #20253a;
+		font-family: system-ui, sans-serif;
+	}
+	.tab-bar button {
+		font: inherit;
+		font-size: 0.9rem;
+		padding: 0.4rem 0.75rem;
+		background: transparent;
+		color: #aab;
+		border: 0;
+		border-bottom: 2px solid transparent;
+		cursor: pointer;
+	}
+	.tab-bar button.active {
+		color: #e8eaf6;
+		border-bottom-color: #6d8cff;
+	}
+	.tab-bar button:hover:not(.active) {
+		color: #e8eaf6;
+	}
+</style>
diff --git a/ui/frontend/src/lib/sidebar/types.ts b/ui/frontend/src/lib/sidebar/types.ts
new file mode 100644
index 0000000..7e5a155
--- /dev/null
+++ b/ui/frontend/src/lib/sidebar/types.ts
@@ -0,0 +1,9 @@
+// Shared types for the in-game sidebar and the mobile bottom-tabs.
+// Kept as plain TypeScript (instead of a Svelte module export) so
+// every consumer — components, layout, and tests — imports them
+// through the same path without relying on Svelte tooling for
+// type-only re-exports.
+
+export type SidebarTab = "calculator" | "inspector" | "order";
+
+export type MobileTool = "map" | "calc" | "order";
diff --git a/ui/frontend/src/routes/games/[id]/+layout.svelte b/ui/frontend/src/routes/games/[id]/+layout.svelte
new file mode 100644
index 0000000..0f67267
--- /dev/null
+++ b/ui/frontend/src/routes/games/[id]/+layout.svelte
@@ -0,0 +1,92 @@
+<!--
+Phase 10 in-game shell. Composes the header, a conditionally-visible
+sidebar (Calculator / Inspector / Order tabs), the active-view slot
+filled by the child route, and a mobile-only bottom-tab bar. The
+layout owns:
+
+- `sidebarOpen` — tablet-only drawer toggle. Desktop keeps the
+  sidebar pinned via CSS; mobile hides it entirely.
+- `mobileTool` — mobile-only tool overlay state. The tool only
+  visually overrides the active-view slot when the URL is `/map`,
+  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.
+
+State preservation across active-view switches works for free
+because SvelteKit keeps this layout instance mounted while children
+swap.
+-->
+<script lang="ts">
+	import { page } from "$app/state";
+	import Header from "$lib/header/header.svelte";
+	import Sidebar from "$lib/sidebar/sidebar.svelte";
+	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";
+
+	let { children } = $props();
+
+	let sidebarOpen = $state(false);
+	let mobileTool: MobileTool = $state("map");
+
+	const gameId = $derived(page.params.id ?? "");
+	const isOnMap = $derived(/\/games\/[^/]+\/map\/?$/.test(page.url.pathname));
+	const effectiveTool: MobileTool = $derived.by(() =>
+		isOnMap ? mobileTool : "map",
+	);
+
+	function toggleSidebar(): void {
+		sidebarOpen = !sidebarOpen;
+	}
+</script>
+
+<div class="game-shell" data-testid="game-shell">
+	<Header
+		{gameId}
+		{sidebarOpen}
+		onToggleSidebar={toggleSidebar}
+	/>
+	<div class="body">
+		<main class="active-view-host" data-testid="active-view-host">
+			{#if effectiveTool === "calc"}
+				<Calculator />
+			{:else if effectiveTool === "order"}
+				<Order />
+			{:else}
+				{@render children()}
+			{/if}
+		</main>
+		<Sidebar open={sidebarOpen} onClose={() => (sidebarOpen = false)} />
+	</div>
+	<BottomTabs
+		{gameId}
+		activeTool={effectiveTool}
+		onSelectTool={(tool) => (mobileTool = tool)}
+	/>
+</div>
+
+<style>
+	.game-shell {
+		display: flex;
+		flex-direction: column;
+		min-height: 100vh;
+		background: #0a0e1a;
+		color: #e8eaf6;
+	}
+	.body {
+		flex: 1;
+		display: flex;
+		min-height: 0;
+	}
+	.active-view-host {
+		flex: 1;
+		min-width: 0;
+		overflow-y: auto;
+	}
+	@media (max-width: 767.98px) {
+		.body {
+			padding-bottom: 3.25rem;
+		}
+	}
+</style>
diff --git a/ui/frontend/src/routes/games/[id]/+layout.ts b/ui/frontend/src/routes/games/[id]/+layout.ts
new file mode 100644
index 0000000..ce3dd57
--- /dev/null
+++ b/ui/frontend/src/routes/games/[id]/+layout.ts
@@ -0,0 +1,8 @@
+// SPA mode for the in-game shell, mirroring the root layout. The
+// session bootstrap and the auth gate already live in the root
+// `+layout.svelte`; this layout just inherits the SPA flags so the
+// static adapter does not try to prerender a per-game shell at build
+// time.
+
+export const ssr = false;
+export const prerender = false;
diff --git a/ui/frontend/src/routes/games/[id]/+page.ts b/ui/frontend/src/routes/games/[id]/+page.ts
new file mode 100644
index 0000000..a48e9ec
--- /dev/null
+++ b/ui/frontend/src/routes/games/[id]/+page.ts
@@ -0,0 +1,12 @@
+// A bare `/games/:id` URL is not in the IA section — every in-game
+// view sits under one of the typed sub-routes (`map`, `table/...`,
+// etc.). Default the user to the map view so the URL is always
+// pointing at a real active view; SvelteKit's `redirect` runs in the
+// browser because the layout disables SSR.
+
+import { redirect } from "@sveltejs/kit";
+import type { PageLoad } from "./$types";
+
+export const load: PageLoad = ({ params }) => {
+	throw redirect(307, `/games/${params.id}/map`);
+};
diff --git a/ui/frontend/src/routes/games/[id]/battle/[[battleId]]/+page.svelte b/ui/frontend/src/routes/games/[id]/battle/[[battleId]]/+page.svelte
new file mode 100644
index 0000000..d16714b
--- /dev/null
+++ b/ui/frontend/src/routes/games/[id]/battle/[[battleId]]/+page.svelte
@@ -0,0 +1,6 @@
+<script lang="ts">
+	import { page } from "$app/state";
+	import BattleView from "$lib/active-view/battle.svelte";
+</script>
+
+<BattleView battleId={page.params.battleId ?? ""} />
diff --git a/ui/frontend/src/routes/games/[id]/designer/science/[[scienceId]]/+page.svelte b/ui/frontend/src/routes/games/[id]/designer/science/[[scienceId]]/+page.svelte
new file mode 100644
index 0000000..5e28dc3
--- /dev/null
+++ b/ui/frontend/src/routes/games/[id]/designer/science/[[scienceId]]/+page.svelte
@@ -0,0 +1,5 @@
+<script lang="ts">
+	import DesignerScience from "$lib/active-view/designer-science.svelte";
+</script>
+
+<DesignerScience />
diff --git a/ui/frontend/src/routes/games/[id]/designer/ship-class/[[classId]]/+page.svelte b/ui/frontend/src/routes/games/[id]/designer/ship-class/[[classId]]/+page.svelte
new file mode 100644
index 0000000..212c8cc
--- /dev/null
+++ b/ui/frontend/src/routes/games/[id]/designer/ship-class/[[classId]]/+page.svelte
@@ -0,0 +1,5 @@
+<script lang="ts">
+	import DesignerShipClass from "$lib/active-view/designer-ship-class.svelte";
+</script>
+
+<DesignerShipClass />
diff --git a/ui/frontend/src/routes/games/[id]/mail/+page.svelte b/ui/frontend/src/routes/games/[id]/mail/+page.svelte
new file mode 100644
index 0000000..6e27e97
--- /dev/null
+++ b/ui/frontend/src/routes/games/[id]/mail/+page.svelte
@@ -0,0 +1,5 @@
+<script lang="ts">
+	import MailView from "$lib/active-view/mail.svelte";
+</script>
+
+<MailView />
diff --git a/ui/frontend/src/routes/games/[id]/map/+page.svelte b/ui/frontend/src/routes/games/[id]/map/+page.svelte
new file mode 100644
index 0000000..4093cff
--- /dev/null
+++ b/ui/frontend/src/routes/games/[id]/map/+page.svelte
@@ -0,0 +1,5 @@
+<script lang="ts">
+	import MapView from "$lib/active-view/map.svelte";
+</script>
+
+<MapView />
diff --git a/ui/frontend/src/routes/games/[id]/report/+page.svelte b/ui/frontend/src/routes/games/[id]/report/+page.svelte
new file mode 100644
index 0000000..385e371
--- /dev/null
+++ b/ui/frontend/src/routes/games/[id]/report/+page.svelte
@@ -0,0 +1,5 @@
+<script lang="ts">
+	import ReportView from "$lib/active-view/report.svelte";
+</script>
+
+<ReportView />
diff --git a/ui/frontend/src/routes/games/[id]/table/[entity]/+page.svelte b/ui/frontend/src/routes/games/[id]/table/[entity]/+page.svelte
new file mode 100644
index 0000000..ab28064
--- /dev/null
+++ b/ui/frontend/src/routes/games/[id]/table/[entity]/+page.svelte
@@ -0,0 +1,6 @@
+<script lang="ts">
+	import { page } from "$app/state";
+	import TableView from "$lib/active-view/table.svelte";
+</script>
+
+<TableView entity={page.params.entity ?? ""} />
diff --git a/ui/frontend/tests/e2e/game-shell.spec.ts b/ui/frontend/tests/e2e/game-shell.spec.ts
new file mode 100644
index 0000000..6b85053
--- /dev/null
+++ b/ui/frontend/tests/e2e/game-shell.spec.ts
@@ -0,0 +1,219 @@
+// Phase 10 end-to-end coverage for the in-game shell. Every spec
+// boots an authenticated session through `/__debug/store` (no
+// gateway calls — the shell makes none in Phase 10), navigates into
+// `/games/test-shell/map`, and exercises one slice of the chrome:
+// header navigation, sidebar tab preservation, mobile bottom-tabs,
+// and the breakpoint switches at 768 / 1024 px.
+
+import { expect, test, type Page } from "@playwright/test";
+
+// The `window.__galaxyDebug` surface is owned by
+// `src/routes/__debug/store/+page.svelte` and typed by
+// `tests/e2e/storage-keypair-persistence.spec.ts`. This spec only
+// needs the auth-bootstrap subset (`clearSession`,
+// `setDeviceSessionId`); the merged global declaration covers both.
+
+const SESSION_ID = "phase-10-shell-session";
+const GAME_ID = "test-shell";
+
+async function bootShell(page: Page): Promise<void> {
+	await page.goto("/__debug/store");
+	await expect(page.getByTestId("debug-store-ready")).toBeVisible();
+	await page.waitForFunction(() => window.__galaxyDebug?.ready === true);
+	await page.evaluate(() => window.__galaxyDebug!.clearSession());
+	await page.evaluate(
+		(id) => window.__galaxyDebug!.setDeviceSessionId(id),
+		SESSION_ID,
+	);
+	await page.goto(`/games/${GAME_ID}/map`);
+	await expect(page.getByTestId("game-shell")).toBeVisible();
+	await expect(page.getByTestId("active-view-map")).toBeVisible();
+}
+
+test("shell mounts with header / sidebar / active-view chrome", async ({
+	page,
+}) => {
+	await bootShell(page);
+	await expect(page.getByTestId("game-shell-header")).toBeVisible();
+	await expect(page.getByTestId("race-name")).toContainText("race ?");
+	await expect(page.getByTestId("turn-counter")).toContainText("turn");
+	await expect(page.getByTestId("view-menu-trigger")).toBeVisible();
+	await expect(page.getByTestId("account-menu-trigger")).toBeVisible();
+});
+
+test("header view-menu navigates to every active view", async ({ page }) => {
+	await bootShell(page);
+
+	const destinations: Array<[string, string, string]> = [
+		["view-menu-item-report", "active-view-report", "/report"],
+		["view-menu-item-mail", "active-view-mail", "/mail"],
+		["view-menu-item-battle", "active-view-battle", "/battle"],
+		[
+			"view-menu-item-designer-ship-class",
+			"active-view-designer-ship-class",
+			"/designer/ship-class",
+		],
+		[
+			"view-menu-item-designer-science",
+			"active-view-designer-science",
+			"/designer/science",
+		],
+		["view-menu-item-map", "active-view-map", "/map"],
+	];
+
+	for (const [trigger, viewTestId, urlSuffix] of destinations) {
+		await page.getByTestId("view-menu-trigger").click();
+		await page.getByTestId(trigger).click();
+		await expect(page.getByTestId(viewTestId)).toBeVisible();
+		await expect(page).toHaveURL(new RegExp(`/games/${GAME_ID}${urlSuffix}$`));
+	}
+});
+
+test("header view-menu Tables sub-list navigates to every entity", async ({
+	page,
+}) => {
+	await bootShell(page);
+	const entities = [
+		"planets",
+		"ship-classes",
+		"ship-groups",
+		"fleets",
+		"sciences",
+		"races",
+	];
+	for (const entity of entities) {
+		await page.getByTestId("view-menu-trigger").click();
+		await page
+			.getByTestId("view-menu-tables")
+			.locator("summary")
+			.click();
+		await page.getByTestId(`view-menu-item-table-${entity}`).click();
+		const view = page.getByTestId("active-view-table");
+		await expect(view).toBeVisible();
+		await expect(view).toHaveAttribute("data-entity", entity);
+		await expect(page).toHaveURL(
+			new RegExp(`/games/${GAME_ID}/table/${entity}$`),
+		);
+	}
+});
+
+test("sidebar tab choice survives navigation between active views", async ({
+	page,
+	browserName,
+}, testInfo) => {
+	test.skip(
+		testInfo.project.name.startsWith("chromium-mobile") ||
+			testInfo.project.name === "webkit-desktop"
+			? false
+			: false,
+		"sidebar test runs on every project",
+	);
+	await bootShell(page);
+	// Skip on viewports below 1024 — sidebar is hidden by CSS there.
+	const viewport = page.viewportSize();
+	if (viewport === null || viewport.width < 1024) {
+		test.skip();
+		return;
+	}
+	void browserName;
+
+	await page.getByTestId("sidebar-tab-calculator").click();
+	await expect(page.getByTestId("sidebar-tool-calculator")).toBeVisible();
+
+	await page.getByTestId("view-menu-trigger").click();
+	await page.getByTestId("view-menu-item-report").click();
+	await expect(page.getByTestId("active-view-report")).toBeVisible();
+
+	// Sidebar still rendered; the calculator tool remains selected.
+	await expect(page.getByTestId("sidebar-tool-calculator")).toBeVisible();
+	await expect(page.getByTestId("sidebar")).toHaveAttribute(
+		"data-active-tab",
+		"calculator",
+	);
+
+	await page.getByTestId("view-menu-trigger").click();
+	await page.getByTestId("view-menu-item-map").click();
+	await expect(page.getByTestId("active-view-map")).toBeVisible();
+	await expect(page.getByTestId("sidebar")).toHaveAttribute(
+		"data-active-tab",
+		"calculator",
+	);
+});
+
+test("mobile bottom-tabs show on small viewports and toggle the tool overlay", async ({
+	page,
+}, testInfo) => {
+	if (!testInfo.project.name.startsWith("chromium-mobile")) {
+		test.skip();
+		return;
+	}
+	await bootShell(page);
+
+	await expect(page.getByTestId("bottom-tabs")).toBeVisible();
+	await expect(page.getByTestId("sidebar")).not.toBeVisible();
+
+	await page.getByTestId("bottom-tab-calc").click();
+	await expect(page.getByTestId("sidebar-tool-calculator")).toBeVisible();
+
+	await page.getByTestId("bottom-tab-order").click();
+	await expect(page.getByTestId("sidebar-tool-order")).toBeVisible();
+
+	await page.getByTestId("bottom-tab-map").click();
+	await expect(page.getByTestId("active-view-map")).toBeVisible();
+});
+
+test("mobile More drawer navigates to every destination", async ({
+	page,
+}, testInfo) => {
+	if (!testInfo.project.name.startsWith("chromium-mobile")) {
+		test.skip();
+		return;
+	}
+	await bootShell(page);
+
+	await page.getByTestId("bottom-tab-more").click();
+	await expect(page.getByTestId("bottom-tabs-more-drawer")).toBeVisible();
+	await page.getByTestId("bottom-tabs-more-mail").click();
+	await expect(page.getByTestId("active-view-mail")).toBeVisible();
+
+	await page.getByTestId("bottom-tab-more").click();
+	await page.getByTestId("bottom-tabs-more-report").click();
+	await expect(page.getByTestId("active-view-report")).toBeVisible();
+});
+
+test("breakpoint switches between desktop / tablet / mobile", async ({
+	page,
+}, testInfo) => {
+	// Use a single chromium-desktop run to drive all three viewports in
+	// the same browser. Other projects skip — the viewport diff is the
+	// goal here, not browser-specific behaviour.
+	if (testInfo.project.name !== "chromium-desktop") {
+		test.skip();
+		return;
+	}
+	await bootShell(page);
+
+	// Desktop ≥ 1024: sidebar visible, bottom-tabs hidden, sidebar
+	// toggle hidden.
+	await page.setViewportSize({ width: 1280, height: 800 });
+	await expect(page.getByTestId("sidebar")).toBeVisible();
+	await expect(page.getByTestId("bottom-tabs")).not.toBeVisible();
+	await expect(page.getByTestId("sidebar-toggle")).not.toBeVisible();
+
+	// Tablet 768–1024: sidebar hidden by default, sidebar toggle
+	// visible, bottom-tabs hidden. Click the toggle and the sidebar
+	// becomes visible again.
+	await page.setViewportSize({ width: 900, height: 800 });
+	await expect(page.getByTestId("sidebar")).not.toBeVisible();
+	await expect(page.getByTestId("sidebar-toggle")).toBeVisible();
+	await expect(page.getByTestId("bottom-tabs")).not.toBeVisible();
+	await page.getByTestId("sidebar-toggle").click();
+	await expect(page.getByTestId("sidebar")).toBeVisible();
+
+	// Mobile < 768: sidebar hidden entirely, bottom-tabs visible,
+	// sidebar toggle hidden again.
+	await page.setViewportSize({ width: 390, height: 800 });
+	await expect(page.getByTestId("bottom-tabs")).toBeVisible();
+	await expect(page.getByTestId("sidebar")).not.toBeVisible();
+	await expect(page.getByTestId("sidebar-toggle")).not.toBeVisible();
+});
diff --git a/ui/frontend/tests/game-shell-header.test.ts b/ui/frontend/tests/game-shell-header.test.ts
new file mode 100644
index 0000000..abea334
--- /dev/null
+++ b/ui/frontend/tests/game-shell-header.test.ts
@@ -0,0 +1,140 @@
+// Component tests for the Phase 10 in-game shell header. The header
+// composes the static `race ?` placeholder, the placeholder
+// turn-counter (Phase 11 wires the live source), the view-menu, and
+// the account-menu. The tests assert the placeholder copy, that
+// every view-menu entry dispatches `goto` with the right URL, and
+// that the Logout entry of the account-menu calls
+// `session.signOut("user")`.
+
+import "@testing-library/jest-dom/vitest";
+import { fireEvent, render } from "@testing-library/svelte";
+import {
+	afterEach,
+	beforeEach,
+	describe,
+	expect,
+	test,
+	vi,
+} from "vitest";
+
+import { i18n } from "../src/lib/i18n/index.svelte";
+import { session } from "../src/lib/session-store.svelte";
+import Header from "../src/lib/header/header.svelte";
+
+const gotoSpy = vi.fn(async (..._args: unknown[]) => {});
+vi.mock("$app/navigation", () => ({
+	goto: (...args: unknown[]) => gotoSpy(...args),
+}));
+
+beforeEach(() => {
+	i18n.resetForTests("en");
+	gotoSpy.mockReset();
+	vi.spyOn(session, "signOut").mockResolvedValue(undefined);
+});
+
+afterEach(() => {
+	vi.restoreAllMocks();
+});
+
+describe("game-shell header", () => {
+	test("renders the static race / turn placeholders and toggles", () => {
+		const onToggleSidebar = vi.fn();
+		const ui = render(Header, {
+			props: { gameId: "g1", sidebarOpen: false, onToggleSidebar },
+		});
+		expect(ui.getByTestId("race-name")).toHaveTextContent("race ?");
+		expect(ui.getByTestId("turn-counter").textContent ?? "").toMatch(
+			/turn\s+\?/,
+		);
+		expect(ui.getByTestId("view-menu-trigger")).toBeInTheDocument();
+		expect(ui.getByTestId("account-menu-trigger")).toBeInTheDocument();
+	});
+
+	test("clicking the sidebar toggle invokes the prop callback", async () => {
+		const onToggleSidebar = vi.fn();
+		const ui = render(Header, {
+			props: { gameId: "g1", sidebarOpen: false, onToggleSidebar },
+		});
+		await fireEvent.click(ui.getByTestId("sidebar-toggle"));
+		expect(onToggleSidebar).toHaveBeenCalledTimes(1);
+	});
+
+	test("view-menu navigates to every IA destination", async () => {
+		const ui = render(Header, {
+			props: { gameId: "g1", sidebarOpen: false, onToggleSidebar: () => {} },
+		});
+
+		const destinations: Array<[string, string]> = [
+			["view-menu-item-map", "/games/g1/map"],
+			["view-menu-item-report", "/games/g1/report"],
+			["view-menu-item-battle", "/games/g1/battle"],
+			["view-menu-item-mail", "/games/g1/mail"],
+			[
+				"view-menu-item-designer-ship-class",
+				"/games/g1/designer/ship-class",
+			],
+			[
+				"view-menu-item-designer-science",
+				"/games/g1/designer/science",
+			],
+		];
+
+		for (const [testId, href] of destinations) {
+			await fireEvent.click(ui.getByTestId("view-menu-trigger"));
+			await fireEvent.click(ui.getByTestId(testId));
+			expect(gotoSpy).toHaveBeenLastCalledWith(href);
+		}
+	});
+
+	test("view-menu Tables sub-list navigates to every entity", async () => {
+		const ui = render(Header, {
+			props: { gameId: "g1", sidebarOpen: false, onToggleSidebar: () => {} },
+		});
+		const tableEntities: Array<[string, string]> = [
+			["view-menu-item-table-planets", "/games/g1/table/planets"],
+			[
+				"view-menu-item-table-ship-classes",
+				"/games/g1/table/ship-classes",
+			],
+			[
+				"view-menu-item-table-ship-groups",
+				"/games/g1/table/ship-groups",
+			],
+			["view-menu-item-table-fleets", "/games/g1/table/fleets"],
+			["view-menu-item-table-sciences", "/games/g1/table/sciences"],
+			["view-menu-item-table-races", "/games/g1/table/races"],
+		];
+		for (const [testId, href] of tableEntities) {
+			await fireEvent.click(ui.getByTestId("view-menu-trigger"));
+			// Open the Tables sub-disclosure each iteration; the menu
+			// closes on every navigation.
+			const summary = ui
+				.getByTestId("view-menu-tables")
+				.querySelector("summary");
+			if (summary !== null) {
+				await fireEvent.click(summary);
+			}
+			await fireEvent.click(ui.getByTestId(testId));
+			expect(gotoSpy).toHaveBeenLastCalledWith(href);
+		}
+	});
+
+	test("account-menu Logout triggers session.signOut('user')", async () => {
+		const ui = render(Header, {
+			props: { gameId: "g1", sidebarOpen: false, onToggleSidebar: () => {} },
+		});
+		await fireEvent.click(ui.getByTestId("account-menu-trigger"));
+		await fireEvent.click(ui.getByTestId("account-menu-logout"));
+		expect(session.signOut).toHaveBeenCalledWith("user");
+	});
+
+	test("account-menu language picker switches the i18n locale", async () => {
+		const ui = render(Header, {
+			props: { gameId: "g1", sidebarOpen: false, onToggleSidebar: () => {} },
+		});
+		await fireEvent.click(ui.getByTestId("account-menu-trigger"));
+		const select = ui.getByTestId("account-menu-language-select");
+		await fireEvent.change(select, { target: { value: "ru" } });
+		expect(i18n.locale).toBe("ru");
+	});
+});
diff --git a/ui/frontend/tests/game-shell-sidebar.test.ts b/ui/frontend/tests/game-shell-sidebar.test.ts
new file mode 100644
index 0000000..858e21b
--- /dev/null
+++ b/ui/frontend/tests/game-shell-sidebar.test.ts
@@ -0,0 +1,98 @@
+// Component tests for the Phase 10 in-game shell sidebar. Validates
+// the default selected tab, the Calculator / Inspector / Order
+// switching, the empty-state copy that matches the IA section, and
+// the `?sidebar=` URL seed convention used by the mobile bottom-tabs.
+
+import "@testing-library/jest-dom/vitest";
+import { fireEvent, render } from "@testing-library/svelte";
+import {
+	beforeEach,
+	describe,
+	expect,
+	test,
+	vi,
+} from "vitest";
+
+import { i18n } from "../src/lib/i18n/index.svelte";
+
+const pageMock = vi.hoisted(() => ({
+	url: new URL("http://localhost/games/g1/map"),
+	params: { id: "g1" } as Record<string, string>,
+}));
+
+vi.mock("$app/state", () => ({
+	page: pageMock,
+}));
+
+import Sidebar from "../src/lib/sidebar/sidebar.svelte";
+
+beforeEach(() => {
+	i18n.resetForTests("en");
+	pageMock.url = new URL("http://localhost/games/g1/map");
+});
+
+describe("game-shell sidebar", () => {
+	test("renders the inspector tab content by default", () => {
+		const ui = render(Sidebar, {
+			props: { open: false, onClose: () => {} },
+		});
+		expect(ui.getByTestId("sidebar-tool-inspector")).toBeInTheDocument();
+		expect(ui.getByTestId("sidebar-tool-inspector")).toHaveTextContent(
+			"select an object on the map",
+		);
+		expect(ui.getByTestId("sidebar")).toHaveAttribute(
+			"data-active-tab",
+			"inspector",
+		);
+	});
+
+	test("switching tabs updates the rendered tool", async () => {
+		const ui = render(Sidebar, {
+			props: { open: false, onClose: () => {} },
+		});
+		await fireEvent.click(ui.getByTestId("sidebar-tab-calculator"));
+		expect(ui.getByTestId("sidebar-tool-calculator")).toBeInTheDocument();
+		expect(ui.queryByTestId("sidebar-tool-inspector")).toBeNull();
+		expect(ui.queryByTestId("sidebar-tool-order")).toBeNull();
+
+		await fireEvent.click(ui.getByTestId("sidebar-tab-order"));
+		expect(ui.getByTestId("sidebar-tool-order")).toBeInTheDocument();
+		expect(ui.queryByTestId("sidebar-tool-calculator")).toBeNull();
+	});
+
+	test("empty-state copy matches the IA section verbatim", () => {
+		const ui = render(Sidebar, {
+			props: { open: false, onClose: () => {} },
+		});
+		expect(ui.getByTestId("sidebar-tool-inspector")).toHaveTextContent(
+			"select an object on the map",
+		);
+	});
+
+	test("?sidebar=calc seeds the calculator tab on first mount", () => {
+		pageMock.url = new URL("http://localhost/games/g1/map?sidebar=calc");
+		const ui = render(Sidebar, {
+			props: { open: false, onClose: () => {} },
+		});
+		expect(ui.getByTestId("sidebar-tool-calculator")).toBeInTheDocument();
+		expect(ui.getByTestId("sidebar")).toHaveAttribute(
+			"data-active-tab",
+			"calculator",
+		);
+	});
+
+	test("?sidebar=order seeds the order tab on first mount", () => {
+		pageMock.url = new URL("http://localhost/games/g1/map?sidebar=order");
+		const ui = render(Sidebar, {
+			props: { open: false, onClose: () => {} },
+		});
+		expect(ui.getByTestId("sidebar-tool-order")).toBeInTheDocument();
+	});
+
+	test("close button calls the onClose prop", async () => {
+		const onClose = vi.fn();
+		const ui = render(Sidebar, { props: { open: true, onClose } });
+		await fireEvent.click(ui.getByTestId("sidebar-close"));
+		expect(onClose).toHaveBeenCalledTimes(1);
+	});
+});
diff --git a/ui/frontend/tests/game-shell-stubs.test.ts b/ui/frontend/tests/game-shell-stubs.test.ts
new file mode 100644
index 0000000..0db8052
--- /dev/null
+++ b/ui/frontend/tests/game-shell-stubs.test.ts
@@ -0,0 +1,83 @@
+// Component tests for every Phase 10 active-view stub. Each stub
+// renders the localised view title plus the `coming soon` body copy
+// and exposes a stable `data-testid` so later phases can replace the
+// content without renaming the test hook. The table stub additionally
+// honours its `entity` prop and falls back to the snake_case i18n key
+// for an unknown slug.
+
+import "@testing-library/jest-dom/vitest";
+import { render } from "@testing-library/svelte";
+import { beforeEach, describe, expect, test } from "vitest";
+
+import { i18n } from "../src/lib/i18n/index.svelte";
+
+import MapView from "../src/lib/active-view/map.svelte";
+import TableView from "../src/lib/active-view/table.svelte";
+import ReportView from "../src/lib/active-view/report.svelte";
+import BattleView from "../src/lib/active-view/battle.svelte";
+import MailView from "../src/lib/active-view/mail.svelte";
+import DesignerShipClass from "../src/lib/active-view/designer-ship-class.svelte";
+import DesignerScience from "../src/lib/active-view/designer-science.svelte";
+
+beforeEach(() => {
+	i18n.resetForTests("en");
+});
+
+describe("active-view stubs", () => {
+	test("map stub renders title and coming-soon copy", () => {
+		const ui = render(MapView);
+		const node = ui.getByTestId("active-view-map");
+		expect(node).toHaveTextContent("map");
+		expect(node).toHaveTextContent("coming soon");
+	});
+
+	test("table stub maps a kebab-case entity to the right i18n title", () => {
+		const ui = render(TableView, { props: { entity: "ship-classes" } });
+		const node = ui.getByTestId("active-view-table");
+		expect(node).toHaveAttribute("data-entity", "ship-classes");
+		expect(node).toHaveTextContent("ship classes");
+		expect(node).toHaveTextContent("coming soon");
+	});
+
+	test("table stub also handles a single-word entity", () => {
+		const ui = render(TableView, { props: { entity: "planets" } });
+		expect(ui.getByTestId("active-view-table")).toHaveTextContent("planets");
+	});
+
+	test("report / mail / designer stubs render their localised titles", () => {
+		const r = render(ReportView);
+		expect(r.getByTestId("active-view-report")).toHaveTextContent(
+			"turn report",
+		);
+
+		const m = render(MailView);
+		expect(m.getByTestId("active-view-mail")).toHaveTextContent(
+			"diplomatic mail",
+		);
+
+		const sc = render(DesignerShipClass);
+		expect(
+			sc.getByTestId("active-view-designer-ship-class"),
+		).toHaveTextContent("ship-class designer");
+
+		const sci = render(DesignerScience);
+		expect(
+			sci.getByTestId("active-view-designer-science"),
+		).toHaveTextContent("science designer");
+	});
+
+	test("battle stub stamps the battleId on the host element", () => {
+		const ui = render(BattleView, { props: { battleId: "b-42" } });
+		const node = ui.getByTestId("active-view-battle");
+		expect(node).toHaveAttribute("data-battle-id", "b-42");
+		expect(node).toHaveTextContent("battle log");
+	});
+
+	test("battle stub accepts an empty battleId for the list URL", () => {
+		const ui = render(BattleView, { props: { battleId: "" } });
+		expect(ui.getByTestId("active-view-battle")).toHaveAttribute(
+			"data-battle-id",
+			"",
+		);
+	});
+});