ui/phase-12: order composer skeleton

OrderDraftStore persists per-game command drafts in Cache; the
sidebar Order tab renders the list with a per-row delete control.
The layout passes a `historyMode` prop through Sidebar / BottomTabs
as a constant `false`, so Phase 26 only flips the source.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

ui/PLAN.md

@@ -1332,17 +1332,97 @@ Goal: implement the empty order composer as a persistent vertical list
 that survives navigation and reloads, ready to receive commands in
 later phases.
 
-Artifacts:
+Decisions taken with the project owner during implementation:
 
-- `ui/frontend/src/lib/sidebar/order-tab.svelte` vertical command list
-  with empty state copy
-- `ui/frontend/src/sync/order-draft.ts` draft order store backed by
-  `Cache`, persisting across reloads
-- `ui/frontend/src/sync/order-types.ts` typed command shape
-  (`OrderCommand` discriminated union)
-- topic doc `ui/docs/order-composer.md` describing the
-  draft-replaces-server-order model, the local-validation invariant,
-  and command status semantics
+1. **Store filename uses the runes extension.** PLAN.md originally
+   listed `ui/frontend/src/sync/order-draft.ts`. Svelte 5 runes only
+   compile inside `*.svelte` / `*.svelte.ts` files; the draft state
+   has to be reactive so `order-tab.svelte` re-renders on
+   add/remove/move. The artifact ships as
+   `ui/frontend/src/sync/order-draft.svelte.ts`, mirroring the
+   Phase 11 `lib/game-state.svelte.ts` pattern.
+2. **Single `placeholder` variant in the discriminated union.** The
+   project compactness rule rejects defining surface for the next
+   phase. Phase 14 owns `planetRename` end-to-end (inspector UI,
+   command type, submit pipeline, server-result merging) and is the
+   right place to add the first real variant. Phase 12 ships exactly
+   one variant — `{ kind: "placeholder"; id: string; label: string }`
+   — sufficient for the add/remove/reorder/persist tests.
+3. **Reorder API is `move(fromIndex, toIndex)`.** One canonical
+   operation; up/down at the call site is a one-line index
+   arithmetic. No `moveUp`/`moveDown` aliases.
+4. **Write-on-every-mutation persistence.** `add`/`remove`/`move`
+   each call `Cache.put` with the full draft snapshot. Phase 25 may
+   profile the submit pipeline and batch writes if needed; until
+   then deterministic writes are easier to test.
+5. **Per-game scoping via Svelte context.** One `OrderDraftStore`
+   instance per game is created in `routes/games/[id]/+layout.svelte`
+   alongside `GameStateStore`, exposed through
+   `ORDER_DRAFT_CONTEXT_KEY`, disposed on layout destroy.
+6. **`historyMode` as a prop, not a module.** Layout passes
+   `historyMode={false}` (a constant in Phase 12) to `Sidebar` and
+   `BottomTabs`; both forward to their tab-bar children which omit
+   the order entry when the flag is true. Phase 26 introduces the
+   real `lib/history-mode.ts` module and replaces the constant in
+   one place.
+7. **Empty-state copy is `order is empty` / `приказ пуст`.** The
+   `coming soon` placeholder text is replaced; per-row delete
+   button reads `delete` / `удалить`.
+8. **e2e seeding via `__galaxyDebug.seedOrderDraft`.** The existing
+   debug surface in `routes/__debug/store/+page.svelte` is extended
+   with `seedOrderDraft(gameId, commands)` and
+   `clearOrderDraft(gameId)` helpers that write directly to the
+   `order-drafts` cache namespace. The store loads the seeded draft
+   on the next layout mount the same way it would after a real
+   reload.
+9. **Race / disposal hygiene mirrors `GameStateStore`.** Mutations
+   are gated on `status === "ready"` so calls before `init`
+   resolves are no-ops, and `persist` checks a `destroyed` flag so
+   in-flight writes after `dispose` resolve into nothing.
+
+Artifacts (delivered):
+
+- `ui/frontend/src/sync/order-types.ts` — `OrderCommand`
+  discriminated union (single `placeholder` variant) and
+  `CommandStatus` lifecycle type.
+- `ui/frontend/src/sync/order-draft.svelte.ts` —
+  `OrderDraftStore` runes class with
+  `init` / `add` / `remove` / `move` / `dispose`, plus
+  `ORDER_DRAFT_CONTEXT_KEY`. Persists the full draft on every
+  mutation under namespace `order-drafts`, key `{gameId}/draft`.
+- `ui/frontend/src/lib/sidebar/order-tab.svelte` — replaces the
+  Phase 10 stub. Empty state from `game.sidebar.empty.order`;
+  ordered list with stable `data-testid="order-command-{i}"`
+  rows and a per-row delete button.
+- `ui/frontend/src/lib/sidebar/sidebar.svelte`,
+  `tab-bar.svelte`, `bottom-tabs.svelte` — `historyMode` prop on
+  the sidebar forwards to `hideOrder` on tab-bar / bottom-tabs;
+  active-tab `order` is reset to `inspector` if the flag flips
+  on, and the `?sidebar=order` URL seed falls back to
+  `inspector` while the flag is true.
+- `ui/frontend/src/routes/games/[id]/+layout.svelte` —
+  instantiates `OrderDraftStore`, sets context, runs
+  `init({ cache, gameId })` next to `gameState.init` through
+  one `Promise.all`, disposes on destroy, passes
+  `historyMode={false}` down.
+- `ui/frontend/src/routes/__debug/store/+page.svelte` — extended
+  `DebugSurface` with `seedOrderDraft` / `clearOrderDraft`.
+- `ui/frontend/src/lib/i18n/locales/{en,ru}.ts` — new
+  `game.sidebar.order.command_delete` key plus updated
+  `game.sidebar.empty.order` copy.
+- `ui/docs/order-composer.md` — topic doc describing the
+  draft-replaces-server-order model, local-validation invariant,
+  command status state machine, persistence, history-mode wiring,
+  and test layout. Cross-references `storage.md` and
+  `navigation.md`.
+- `ui/docs/storage.md` — namespace registry row for
+  `order-drafts`.
+- `ui/docs/navigation.md` — describes the historyMode prop wiring
+  through Sidebar / BottomTabs.
+- `ui/README.md` — new entry under topic docs for
+  `order-composer.md`.
+- Vitest: `ui/frontend/tests/order-draft.test.ts`.
+- Playwright: `ui/frontend/tests/e2e/order-composer.spec.ts`.
 
 Dependencies: Phases 6, 10.