diff --git a/DIVERGENCES.md b/DIVERGENCES.md
index 725ee85a54..8266f5d496 100644
--- a/DIVERGENCES.md
+++ b/DIVERGENCES.md
@@ -100,6 +100,8 @@ from the squash message first, or use a plain merge.
 | `packages/app/src/components/titlebar.tsx` | Two changes, both to the **v2 titlebar branch only** (`useV2Titlebar()`); the legacy branch below it is untouched. (1) The Home button (and its `home.toggle` command, `mod+b`) opens a new session instead of toggling between `/` and the last active tab: `tabs.toggleHome(...)` becomes a `goHome` that selects an already-open draft if there is one and otherwise falls through to the existing `openNewTab()` project-resolution chain. Its pressed / `aria-pressed` state keys on `layout.route().type === "draft"` rather than `"home"`. The icon, label (`home.title`) and keybind are unchanged, as is `tabs.toggleHome` itself, which is simply no longer called. (2) `<ChannelIndicator>` is dropped from that row and the component gains an `export`, so the sidebar can render the DEV/BETA badge at its bottom instead; `Titlebar` keeps its `debugTools` prop because the legacy branch still renders the badge inline. (3) Two buttons added to the row: a sidebar collapse toggle (`sidebar-right` icon, `data-action="titlebar-sidebar-toggle"`, `pressed` while open) as its **first** child, ahead of the `windows() || linux()` `WindowsAppMenu`; and a Search button (`magnifying-glass`, `data-action="titlebar-search"`) immediately after Home, navigating to `/?focus=search`. The toggle reads the fork-only `useAppSidebar()` and is wrapped in `<Show when={appSidebar}>`, which is what keeps it out of the legacy shell. Labels reuse the existing `command.sidebar.toggle` and `home.sessions.search.placeholder` keys — no new i18n. | The home screen is a new session in this fork, so Home has to go there; toggling into the recent-sessions list contradicted that. Reuse-before-create keeps repeated presses from stacking up draft tabs — unlike the New session button, which is expected to always make a new one. Moving the badge lets Home lead the titlebar (measured: x 137 → 92 on macOS, the traffic-light inset). | Keep our `goHome` and the removed indicator. If upstream reworks the titlebar, re-apply both rather than restoring `toggleHome` or the inline badge. If upstream deletes `tabs.toggleHome`, nothing here breaks. Do not remove `Titlebar`'s `debugTools` prop — the legacy titlebar still needs it. Keep `useAppSidebar()` optional-by-design: `useV2Titlebar()` is just `newLayoutDesigns()`, so this titlebar also renders inside the legacy shell, which has no provider — swapping it for `createSimpleContext` would throw there (verified: with the new layout off, the legacy shell renders its own rail, no toggle, and no exception). |
 | `packages/app/src/pages/layout-new.tsx` (again) | Mounts the fork-only `<LaunchNewSession />`, which on desktop redirects one time per boot to a new-session draft (reusing an existing empty draft rather than stacking one up per launch). It pins its decision to the pathname the window came up on and disarms as soon as anything navigates, so it can never hijack a later visit to `/` — the sidebar's "View all" links there. Desktop-only: in the browser there is no "launch" distinct from "navigate to /", so redirecting would make the recents screen unreachable by URL and would break two `packages/app/e2e` specs that `goto("/")`. | Launching should put you in front of a prompt, the way Claude Desktop does, rather than on a list. This supersedes the desktop's restore-last-screen behaviour (`getLastActiveUrl`, `packages/desktop/src/renderer/index.tsx`); the previous session stays one click away in Recents and its tab is still restored. | Keep the mount. If upstream restructures this layout, re-add it. Do not "simplify" the boot-window guard into a plain `location.pathname === "/"` check — that is the bug it exists to prevent. |
 | `packages/app/src/pages/layout-new.tsx`, `packages/app/src/pages/home.tsx`, `packages/app/src/i18n/{en,es}.ts` | **Persistent app sidebar.** Upstream's project column is an `<aside>` owned by `NewHome`, so it exists only on `/`. It becomes app chrome: `layout-new.tsx` wraps its `<main>` in a row flex and renders the fork-only `<AppSidebar class="hidden lg:flex">` beside it, so the sidebar survives every navigation. **The row components stay in `home.tsx`** — `HomeUtilityNav`, `HomeServerRow`, `HomeProjectList`, `HomeProjectEmpty`, `HomeRecentlyClosedRow` and the classes `HOME_PROJECT_NAV_ROW` / `HOME_PROJECT_NAV_LABEL` / `HOME_SECTION_LABEL` gain an `export` and nothing else, so upstream edits to them still apply cleanly; the fork-only `src/components/app-sidebar.tsx` imports and composes them, adding only the column shell and the Recents section. `home.tsx` otherwise loses just `HomeProjectColumn` (dead once the sidebar owns that composition) and the `NewHome` selection/action block, and its grid collapses from `lg:grid-cols-[280px_minmax(0,720px)]` to one `max-w-[760px]` column. The sub-`lg` `HomeUtilityNav` mount is untouched, so the stacked mobile layout is upstream's. The state both screens need (`focusedServer`, `projects`, `selectedProject`, `newSessionProject`, `projectDirectories`, the session-index query, `openNewSession`, `openProjectNewSession`, `openSession`, `selectProject`, `addProjects`, `editProject`, `closeProject`, `unseenCount`, `clearNotifications`, `chooseProject`, `isBackgroundOpen`, `buildHomeSessionRecords`, `HomeSessionRecord`) moves to fork-only `src/pages/home-model.tsx`, which both callers instantiate — safe because the selection lives in `useLayout().home`, the index is one TanStack query deduped by key, and the server-normalizing effect is idempotent. New i18n keys `sidebar.recents`, `sidebar.recents.new`, `sidebar.recents.viewAll` in `en` + `es`. `layout-new.tsx` additionally wraps its shell in the fork-only `<AppSidebarProvider>` (so the titlebar toggle and the sidebar share one collapse state), `AppSidebar` renders nothing while collapsed, and `NewHome` consumes a `?focus=search` param — clearing it after use, the way `pages/new-session.tsx` handles `?prompt` — to focus the search field for the titlebar's Search button. That focus ref changed from a `let` to a signal because `HomeSessionSearch` binds it from `onMount`, which runs after `NewHome`'s effects, so a plain ref is still undefined when the param arrives. `AppSidebarProvider` also registers the `sidebar.toggle` command (no keybind — `mod+b` is Home's here, unlike in the legacy layout), which is what the app menu's View → Toggle Sidebar dispatches; only `LegacyLayout` registered it before, so that item did nothing on this layout. It lives on the provider, not on `AppSidebar`, so collapsing does not unregister the command that undoes it. Both shells can be mounted at once on `/:dir` routes, so the id may be registered twice there; the command registry keeps the first entry, which is the outer (new-layout) one. Every `data-component`/`data-action` hook is untouched (`home-project-row`, `home-add-project`, `home-session-row`, `home-session-search`, …) because `packages/app/e2e` selects on them. | The desktop app should navigate like Claude Desktop — one always-visible sidebar with Projects, Recents and pinned Settings/Help — instead of losing all navigation the moment a session opens. Exporting the row components in place rather than relocating them keeps `home.tsx` down to ~36 added lines: upstream changes to those components merge without a conflict, which relocating them would have forfeited. | Keep our structure. On conflict take upstream's `home.tsx` wholesale and re-apply the four edits: the `export` keywords, the `HomeProjectColumn` deletion, the `createHomeModel()` swap in `NewHome`, and the single-column grid. If upstream edits an exported row component, just take it. Never let a `data-component`/`data-action` hook drift — the e2e suite has no other handle on these rows. |
+| `packages/app/src/context/settings.tsx`, `packages/app/src/components/settings-general.tsx`, `packages/app/src/components/settings-v2/general.tsx`, `packages/app/src/context/settings.test.ts`, `packages/app/src/pages/session/composer/session-revert-dock.stories.tsx`, deleted `packages/app/src/components/settings-v2/interface-transition.tsx` + `interface-transition.stories.tsx`, deleted `packages/app/e2e/regression/legacy-new-session.spec.ts`, `packages/app/e2e/regression/session-timeline-projection.spec.ts`, `packages/app/e2e/performance/timeline-stability/fixture.ts` | **The legacy layout is retired: the fork ships one layout and no way back.** Upstream runs a timed migration — `oldInterfaceSunset` (a hardcoded date), a per-profile `layoutTransitionEligible` flag, a `newLayoutDesigns` preference and a Settings → General **New layout** switch — so existing users can flip between layouts until the sunset passes. All of it goes. `newLayoutDesigns` becomes `createMemo(() => true)`: reading a constant rather than the persisted value is what makes a profile carrying `newLayoutDesigns: false` (older build, another device via sync, hand-edited store) still come up on the new layout, which suppressing the toggle alone would not. `setNewLayoutDesigns`, `layoutTransitionAvailable`, `newInterfaceNoticeVisible` and `dismissNewInterfaceNotice` are **removed from the context rather than stubbed** — a no-op setter would let a caller look like it was switching layouts, so re-introducing the toggle has to be a compile error. Both Settings screens (v1 `settings-general.tsx` and v2 `settings-v2/general.tsx`) lose their `InterfaceSection` + `InterfaceNoticeSection` and the `<Show>` blocks that mounted them; `interface-transition.tsx` and its story are deleted with their last caller. The sunset machinery in `settings.tsx` goes with it — `oldInterfaceSunset`, `legacyNewLayoutDesignsDefault`, `newLayoutDesignsDefault`, `newLayoutDesignsUpgradeCutoff`, `shouldEnableNewLayout`, `layoutTransitionState`, `maximumSunsetTimeout`, `nextSunsetCheckDelay`, `resolveNewLayoutDesigns`, the retirement `setTimeout` and the two `createEffect`s that wrote `newLayoutDesigns` back to the store — along with their tests; `settings.test.ts` keeps only the `isAppUpgrade` / `shouldDisplayTabsToast` block. **Deliberately kept**: `layoutTransitionEligible`, `layoutTransitionClassified` and `setOldLayoutEligible` (with the desktop `isOldLayoutEligible` IPC that feeds them), because the tabs toast still uses eligibility to tell a fresh profile from an existing install — they no longer gate any layout. Also kept: every `newLayoutDesigns()` **read** in `app.tsx` and the `LegacyServerLayout` / `LegacyHome` code behind them. That shell is still mounted on `/:dir` routes, and leaving the branches in place keeps upstream's edits to them applying cleanly; deleting the legacy layout outright is a far larger diff for no user-visible gain. On the test side `legacy-new-session.spec.ts` is deleted (it asserted a redirect to a route that no longer resolves), `session-timeline-projection.spec.ts` drops its one `settings: { newLayoutDesigns: false }` pin, and the timeline-stability fixture drops the `newLayoutDesigns === false` branch that back-dated `app-version.v1`. The many specs that set `newLayoutDesigns: true` are untouched — the value is simply ignored now. The fork-only `packages/app/e2e/regression/layout-theme-lock.spec.ts` covers both locks from a seeded profile; each of its four cases was checked to fail when the matching source file is reverted to upstream's. | The fork ships one layout. Leaving a switch that drops users into a layout the fork does not design for, style-test or screenshot means two UIs to maintain and support, and the upstream sunset date would have retired it anyway. | Keep ours. On conflict take upstream's file and re-apply: the constant `newLayoutDesigns`, the four removed context members, the two deleted Settings sections. If upstream adds a new layout-preference surface, remove it too rather than wiring it up. Do **not** "restore" `setNewLayoutDesigns` to make a new upstream caller compile — delete the caller. Do not delete the `LegacyServerLayout` branches in `app.tsx`; they are load-bearing on `/:dir` and deliberately left as upstream's. |
+| `packages/ui/src/theme/context.tsx`, `packages/app/public/oc-theme-preload.js`, `packages/app/src/theme-preload.test.ts`, `packages/app/src/pages/layout.tsx`, `packages/app/src/components/settings-general.tsx`, `packages/app/src/components/settings-v2/general.tsx` | **One theme in the web/desktop UI; light and dark are the only axis.** Upstream ships 36 selectable palettes with a Settings → Appearance **Theme** picker and command-palette entries. The fork exposes none of them: OC-2 is the theme, `colorScheme` (system/light/dark) is the only appearance choice. The lock lives at `normalize()` in `theme/context.tsx`, renamed to the exported `normalizeThemeID()` and returning the exported `SHIPPED_THEME_ID` unconditionally — that one function is already on every path (provider init, the `onMount` migration, `load`, the cross-tab `storage` listener, `setTheme`, `previewTheme`), so a stored id from before the picker was removed, or one written by another tab, resolves to OC-2 without a second guard. It is exported (and the six call sites renamed) so `theme/context.test.ts` can cover the invariant directly instead of only through its call sites — the module imports cleanly under `bun test` because `import.meta.glob` is called lazily inside `getFiles()`. It also gives the migration for free: `onMount` already rewrites `opencode-theme-id` and calls `clear()` when the raw value differs from the normalized one, which now drops the stale `opencode-theme-css-{light,dark}` cache. `ids()` returns `["oc-2"]` and `loadThemes()` loads only OC-2 instead of all 36 (it was `Promise.all(themeIDs().map(load))`). The bundled theme JSON, the `names` map and `registerTheme` are **left alone** — unreferenced data costs nothing and keeps upstream's theme edits applying cleanly. `oc-theme-preload.js` does the same rewrite *before* mount, so the first launch after upgrading does not paint the user's old palette for a frame; with no other theme reachable its cached-CSS `<style>` injection is gone and it only sets the mode attributes. Removed surfaces: the **Theme** `SettingsRow`/`SettingsRowV2` in both Settings screens (with the `…/themes` docs "Learn more" link, `themeOptions`, the `ThemeOption` type and the `onMount(loadThemes)` that fed them), and in `pages/layout.tsx` the `theme.cycle` command with its `mod+shift+t` keybind, the `cycleTheme` helper and the `theme.set.<id>` command loop (with `availableThemeEntries`). The **colour-scheme** commands stay: `theme.scheme.cycle` (`mod+shift+s`), the three `theme.scheme.<scheme>` entries and their preview/commit wiring. i18n keys (`settings.general.row.theme.*`, `command.theme.cycle`, `command.theme.set`, `toast.theme.title`) are left in the dicts — unused keys are harmless and removing them only creates conflicts. | Every fork surface — the brand, the icons, the screenshots, the docs — is drawn against OC-2. A palette picker means 36 combinations nobody verifies, and a user on Synthwave '84 files bug reports about a UI the fork never shipped. Light/dark still covers the real need. | Keep ours. Take upstream's surrounding changes; re-apply the `normalize()` constant, the `ids()`/`loadThemes()` narrowing, the preload rewrite, and the removed rows/commands. If upstream adds a new theme-selection surface, remove it rather than wiring it up. Do not "fix" `normalize()` back to the `oc-1 → oc-2` mapping — that mapping is a subset of what it does now. Leave the bundled theme files and `names` map in place; deleting them is a much bigger conflict surface for no gain. |
 | `packages/app/src/pages/session/timeline/message-timeline.tsx` | **Session actions menu extracted.** The ⋯ menu beside the session title — both renderings, the legacy `DropdownMenu` and the v2 `MenuV2`, ~145 lines — and the `DialogDeleteSession` closure move verbatim to the fork-only `packages/app/src/components/session-actions-menu.tsx`, and this file renders `<SessionActionsMenu>` instead, passing its existing `openTitleEditor` / share / `archiveSession` / `deleteSession` as callbacks and its trigger element out through `triggerRef` (the share popover still anchors to it). The extracted dialog takes a resolved `title` and an `onConfirm` rather than a `sessionID`, so the caller supplies `sessionTitle(sync().session.get(id)?.title)`. The `title` store loses `pendingRename`/`pendingShare`: deferring Rename and Share until the menu's `onCloseAutoFocus` is now the component's job, since every caller needs it (a list row's inline editor is blurred by the returning focus exactly as the header's was). Also gains one fork-only `createEffect` that consumes `consumeSessionShareRequest(sessionID())` and opens the share popover — the session rows' Share routes through it. | The sidebar's Recents rows and the home session list open the same menu; three copies of four items would drift. Only this file rendered the menu, so extraction is the smallest way to share it. | Keep the extraction. On conflict, take upstream's `message-timeline.tsx` wholesale and re-apply: delete both inline menu blocks and the local `DialogDeleteSession`, mount `<SessionActionsMenu>` with the same callbacks, drop the two `pending*` store fields, and re-add the share-request effect. If upstream adds a menu item, add it to `session-actions-menu.tsx` (both variants) rather than back here. Do not "simplify" the component's deferred rename/share into a plain `onSelect` — focus return is what it exists to survive. |
 | `packages/app/src/pages/home.tsx` | `HomeSessionRow` gains the same `<SessionActionsMenu>` (hover/focus/menu-open revealed, vertical dots) and inline rename: while renaming, the row renders a `div` with `InlineEditor` instead of the `button`, because an input inside a button is invalid markup and swallows keystrokes into the open-session handler. `NewHome` holds one `createInlineEditorController()` for the list and passes it plus the model down. Its local `archiveSession` is deleted — `createHomeModel()` owns `archiveSession`/`renameSession`/`deleteSession` now, so the sidebar and this screen run one implementation (extends the "state both screens need moves to home-model.tsx" split in the persistent-sidebar row above); the call site becomes `model.archiveSession`. Upstream's `SHOW_HOME_SESSION_ARCHIVE` block is left exactly as-is — the flag is `false`, so it renders nothing, and touching it would widen the diff for no gain. `data-component="home-session-row"` and every other selector are untouched (`packages/app/e2e` binds to them); the menu adds `data-action="session-menu"`. | The Recents rows and "View all" are the same list at two sizes; a menu on one and not the other makes "View all" a dead end. | Keep our row structure. On conflict take upstream's row and re-apply the menu, the editing branch, and the `model.*` action wiring. Never let a `data-component`/`data-action` hook drift. If upstream re-enables `SHOW_HOME_SESSION_ARCHIVE`, drop that block instead — its absolutely-positioned archive button would sit on top of the menu. |
 | `packages/desktop/icons/{dev,beta,prod}/` (all PNGs, `icon.icns`, `icon.ico`, `dock.png`), `packages/desktop/icons/README.md` | Regenerated from the fork-only `packages/desktop/icons/icon.svg` by the fork-only `packages/desktop/scripts/generate-icons.ts`: the brand-red `#ee0033` CoDev "C" — the `--mini` splash badge glyph, at the VS Code extension icon's proportions (unit = 120/1024, mark 480x600 centered) — on a white tile, replacing upstream's black/blueprint "o" mark. All three channels are byte-identical for now (chosen deliberately over upstream's per-channel treatments); the generator still writes them separately so a channel can diverge later. `icon.icns` members and `dock.png` use the macOS Big Sur grid (824/1024 inset + drop shadow); Windows, Linux and Store assets stay full-bleed. README rewritten from the Tauri-CLI + Image2Icon recipe to the generator. The stale Tauri-era `android/` and `ios/` subfolders are left untouched — nothing in the Electron build reads them. | Closes the "desktop app icons need design assets" rebrand gap: the Dock/taskbar icon was still upstream's mark. | Keep our assets and README (binary: take ours wholesale). Regenerate via the script rather than hand-editing; if upstream adds an icon size, add it to `FLAT_PNGS`/`ICONSET` and rerun. |
diff --git a/packages/app/e2e/performance/timeline-stability/fixture.ts b/packages/app/e2e/performance/timeline-stability/fixture.ts
index 5095d95db0..e63445e87d 100644
--- a/packages/app/e2e/performance/timeline-stability/fixture.ts
+++ b/packages/app/e2e/performance/timeline-stability/fixture.ts
@@ -136,9 +136,6 @@ export async function setupTimeline(
         },
       }),
     )
-    if (settings.newLayoutDesigns === false) {
-      localStorage.setItem("app-version.v1", JSON.stringify({ version: "1.17.20" }))
-    }
   }, input.settings ?? {})
   if (input.locale) {
     await page.addInitScript((locale) => {
diff --git a/packages/app/e2e/regression/layout-theme-lock.spec.ts b/packages/app/e2e/regression/layout-theme-lock.spec.ts
new file mode 100644
index 0000000000..317459bf52
--- /dev/null
+++ b/packages/app/e2e/regression/layout-theme-lock.spec.ts
@@ -0,0 +1,129 @@
+import { expect, test, type Page } from "@playwright/test"
+import { mockOpenCodeServer } from "../utils/mock-server"
+import { expectAppVisible } from "../utils/waits"
+
+const directory = "C:/OpenCode/LayoutThemeLock"
+
+// The layout switch and the theme picker are both gone, and neither is merely
+// hidden: a profile that still carries the old preference has to come up on the
+// shipped layout and the shipped theme anyway. These specs seed exactly the
+// stored state that used to select the retired ones.
+async function seed(page: Page, storage: Record<string, string>) {
+  await mockOpenCodeServer(page, {
+    directory,
+    project: {
+      id: "proj_layout_theme_lock",
+      worktree: directory,
+      vcs: "git",
+      name: "layout-theme-lock",
+      time: { created: 1700000000000, updated: 1700000000000 },
+      sandboxes: [],
+    },
+    provider: { all: [], connected: [], default: {} },
+    sessions: [],
+    pageMessages: () => ({ items: [] }),
+  })
+  await page.addInitScript((entries) => {
+    for (const [key, value] of Object.entries(entries)) localStorage.setItem(key, value)
+  }, storage)
+}
+
+const sidebar = (page: Page) => page.locator('[data-component="app-sidebar"]')
+
+test("boots the shipped layout for a profile that had the old one turned on", async ({ page }) => {
+  // Exactly what the retired transition wrote: the preference off, plus a
+  // launch version old enough that the upgrade migration would not flip it.
+  await seed(page, {
+    "settings.v3": JSON.stringify({ general: { newLayoutDesigns: false } }),
+    "app-version.v1": JSON.stringify({ version: "1.17.20" }),
+  })
+
+  await page.goto("/")
+
+  await expectAppVisible(sidebar(page))
+  // app.tsx stamps this straight off the setting, so it is the setting.
+  await expect(page.locator("body[data-new-layout]")).toHaveCount(1)
+  await expect(page.locator("body.text-12-regular")).toHaveCount(0)
+})
+
+test("migrates a theme picked before the picker was removed, before first paint", async ({ page }) => {
+  await seed(page, {
+    "opencode-theme-id": "nightowl",
+    "opencode-theme-css-light": "--background-base:#ff00ff;",
+    "opencode-theme-css-dark": "--background-base:#ff00ff;",
+  })
+  // The old palette would only be on screen between the pre-mount script and
+  // the app applying its own theme, and the app removes the element on the way
+  // past. Watching for it is the only way to see that window from out here.
+  await page.addInitScript(() => {
+    Object.assign(window, { __sawStalePalette: false })
+    new MutationObserver((records) => {
+      for (const record of records) {
+        for (const node of record.addedNodes) {
+          if (node instanceof Element && node.id === "oc-theme-preload") {
+            Object.assign(window, { __sawStalePalette: true })
+          }
+        }
+      }
+      // `document.documentElement` does not exist yet at document_start, so the
+      // observer has to be anchored on the document itself.
+    }).observe(document, { childList: true, subtree: true })
+  })
+
+  await page.goto("/")
+
+  await expectAppVisible(sidebar(page))
+  await expect(page.locator("html")).toHaveAttribute("data-theme", "oc-2")
+  expect(await page.evaluate(() => Reflect.get(window, "__sawStalePalette") === true)).toBe(false)
+  await expect
+    .poll(() =>
+      page.evaluate(() => ({
+        id: localStorage.getItem("opencode-theme-id"),
+        light: localStorage.getItem("opencode-theme-css-light"),
+        dark: localStorage.getItem("opencode-theme-css-dark"),
+      })),
+    )
+    .toEqual({ id: "oc-2", light: null, dark: null })
+})
+
+test("ignores a theme another tab writes", async ({ page }) => {
+  await seed(page, {})
+
+  await page.goto("/")
+  await expectAppVisible(sidebar(page))
+
+  // The cross-tab storage listener takes whatever landed in localStorage, so it
+  // is the one path into the theme that no UI change can close.
+  await page.evaluate(() => {
+    localStorage.setItem("opencode-theme-id", "dracula")
+    window.dispatchEvent(
+      new StorageEvent("storage", { key: "opencode-theme-id", newValue: "dracula", storageArea: localStorage }),
+    )
+  })
+
+  await expect(page.locator("html")).toHaveAttribute("data-theme", "oc-2")
+  await expect(page.locator("#oc-theme-preload")).toHaveCount(0)
+})
+
+test("offers no layout switch and no theme picker in settings", async ({ page }) => {
+  // `layoutTransitionEligible` is what the retired transition gated the switch
+  // on, so seeding it is what makes this a real assertion rather than one that
+  // passes because the profile was never offered the switch anyway.
+  await seed(page, {
+    "settings.v3": JSON.stringify({ general: { layoutTransitionEligible: true } }),
+  })
+
+  await page.goto("/")
+  await expectAppVisible(sidebar(page))
+  await sidebar(page).getByRole("button", { name: "Settings" }).click()
+
+  const dialog = page.locator(".settings-v2-dialog")
+  await expectAppVisible(dialog)
+  await expect(dialog.getByRole("heading", { name: "Appearance" })).toBeVisible()
+
+  await expect(dialog.locator('[data-action="settings-new-layout-designs"]')).toHaveCount(0)
+  await expect(dialog.getByText("New layout")).toHaveCount(0)
+  await expect(dialog.locator('[data-action="settings-theme"]')).toHaveCount(0)
+  // Light/dark survives as the only appearance choice.
+  await expect(dialog.locator('[data-action="settings-color-scheme"]')).toBeVisible()
+})
diff --git a/packages/app/e2e/regression/legacy-new-session.spec.ts b/packages/app/e2e/regression/legacy-new-session.spec.ts
deleted file mode 100644
index 45cd64adcc..0000000000
--- a/packages/app/e2e/regression/legacy-new-session.spec.ts
+++ /dev/null
@@ -1,41 +0,0 @@
-import { expect, test } from "@playwright/test"
-import { base64Encode } from "@opencode-ai/core/util/encode"
-import { mockOpenCodeServer } from "../utils/mock-server"
-
-const draftID = "draft_legacy_new_session"
-const directory = "C:/OpenCode/LegacyNewSession"
-const server = `http://${process.env.PLAYWRIGHT_SERVER_HOST ?? "127.0.0.1"}:${process.env.PLAYWRIGHT_SERVER_PORT ?? "4096"}`
-
-test("redirects a draft to the legacy new-session route", async ({ page }) => {
-  await mockOpenCodeServer(page, {
-    directory,
-    project: {
-      id: "proj_legacy_new_session",
-      worktree: directory,
-      vcs: "git",
-      name: "legacy-new-session",
-      time: { created: 1700000000000, updated: 1700000000000 },
-      sandboxes: [],
-    },
-    provider: { all: [], connected: [], default: {} },
-    sessions: [],
-    pageMessages: () => ({ items: [] }),
-  })
-  await page.addInitScript(
-    ({ directory, draftID, server }) => {
-      localStorage.setItem("settings.v3", JSON.stringify({ general: { newLayoutDesigns: false } }))
-      localStorage.setItem("app-version.v1", JSON.stringify({ version: "1.17.20" }))
-      localStorage.setItem(
-        "opencode.window.browser.dat:tabs",
-        JSON.stringify([{ type: "draft", draftID, server, directory }]),
-      )
-    },
-    { directory, draftID, server },
-  )
-
-  await page.goto(`/new-session?draftId=${draftID}`)
-
-  await expect(page).toHaveURL(`/${base64Encode(directory)}/session`)
-  await expect(page.locator("header[data-tauri-drag-region]")).toBeVisible()
-  await expect(page.locator('[data-component="prompt-input"]')).toBeVisible()
-})
diff --git a/packages/app/e2e/regression/session-timeline-projection.spec.ts b/packages/app/e2e/regression/session-timeline-projection.spec.ts
index b1aabcc32c..c87ee05cf2 100644
--- a/packages/app/e2e/regression/session-timeline-projection.spec.ts
+++ b/packages/app/e2e/regression/session-timeline-projection.spec.ts
@@ -128,7 +128,7 @@ test.describe("session timeline projection", () => {
     await expect(page.locator('[data-timeline-row="TurnGap"]')).toBeVisible()
   })
 
-  test("renders comment strips and historical diff summary overflow", async ({ page }) => {
+  test("renders inline comments and historical diff summary overflow", async ({ page }) => {
     const user = userMessage(
       [
         userText("The user made the following comment regarding lines 4 through 8 of src/a.ts: Keep this stable", {
@@ -154,12 +154,13 @@ test.describe("session timeline projection", () => {
     })
     await setupTimeline(page, {
       messages: [user, assistantMessage(), nextUser, nextAssistant],
-      settings: { newLayoutDesigns: false },
     })
     const scroller = page.locator(".scroll-view__viewport", { has: page.locator("[data-timeline-row]") })
     await scroller.evaluate((element) => (element.scrollTop = 0))
 
-    await expect(page.locator('[data-timeline-row="CommentStrip"]')).toBeVisible()
+    // Comments render inline on the user message; the separate CommentStrip row
+    // was only ever produced by the retired layout.
+    await expect(page.locator('[data-timeline-row="CommentStrip"]')).toHaveCount(0)
     await expect(page.getByText("Keep this stable", { exact: true })).toBeVisible()
     await expect(page.locator('[data-timeline-row="DiffSummary"]')).toBeVisible()
     await expect(page.getByText(/show all/i)).toBeVisible()
diff --git a/packages/app/public/oc-theme-preload.js b/packages/app/public/oc-theme-preload.js
index 11c9b39ec4..637cfa5391 100644
--- a/packages/app/public/oc-theme-preload.js
+++ b/packages/app/public/oc-theme-preload.js
@@ -1,10 +1,14 @@
 ;(function () {
   var key = "opencode-theme-id"
-  var themeId = localStorage.getItem(key) || "oc-2"
 
-  if (themeId === "oc-1") {
-    themeId = "oc-2"
-    localStorage.setItem(key, themeId)
+  // The app ships a single theme (light/dark is the colour-scheme axis, not a
+  // second theme). Any other stored id is a leftover from before the picker was
+  // removed, so rewrite it and drop the cached palette here rather than after
+  // mount — otherwise the window paints the old theme for a frame on the first
+  // launch after the upgrade. With no other theme reachable there is no cached
+  // CSS left to inject, so the preload only has to set the mode attributes.
+  if (localStorage.getItem(key) !== "oc-2") {
+    localStorage.setItem(key, "oc-2")
     localStorage.removeItem("opencode-theme-css-light")
     localStorage.removeItem("opencode-theme-css-dark")
   }
@@ -13,28 +17,11 @@
   var isDark = scheme === "dark" || (scheme === "system" && matchMedia("(prefers-color-scheme: dark)").matches)
   var mode = isDark ? "dark" : "light"
 
-  document.documentElement.dataset.theme = themeId
+  document.documentElement.dataset.theme = "oc-2"
   document.documentElement.dataset.colorScheme = mode
   document.documentElement.style.backgroundColor = isDark ? "#080808" : "#fafafa"
 
   // Update theme-color meta tag to match app color scheme
   var metas = document.querySelectorAll("meta[name='theme-color']")
   if (metas.length > 0) metas[0].setAttribute("content", isDark ? "#080808" : "#fafafa")
-
-  if (themeId === "oc-2") return
-
-  var css = localStorage.getItem("opencode-theme-css-" + mode)
-  if (css) {
-    var style = document.createElement("style")
-    style.id = "oc-theme-preload"
-    style.textContent =
-      ":root{color-scheme:" +
-      mode +
-      ";--text-mix-blend-mode:" +
-      (isDark ? "plus-lighter" : "multiply") +
-      ";" +
-      css +
-      "}"
-    document.head.appendChild(style)
-  }
 })()
diff --git a/packages/app/src/components/settings-general.tsx b/packages/app/src/components/settings-general.tsx
index 1da800edc0..c3e22ff494 100644
--- a/packages/app/src/components/settings-general.tsx
+++ b/packages/app/src/components/settings-general.tsx
@@ -1,14 +1,11 @@
-import { Component, Show, createMemo, createResource, onMount, type JSX } from "solid-js"
+import { Component, Show, createMemo, createResource, type JSX } from "solid-js"
 import { Button } from "@opencode-ai/ui/button"
-import { DOCS_URL } from "@codev/brand"
 import { Icon } from "@opencode-ai/ui/icon"
 import { Select } from "@opencode-ai/ui/select"
 import { Switch } from "@opencode-ai/ui/switch"
 import { TextField } from "@opencode-ai/ui/text-field"
 import { Tooltip } from "@opencode-ai/ui/tooltip"
-import { Tag } from "@opencode-ai/ui/v2/badge-v2"
 import { useTheme, type ColorScheme } from "@opencode-ai/ui/theme/context"
-import { useDialog } from "@opencode-ai/ui/context/dialog"
 import { useParams } from "@solidjs/router"
 import { useLanguage } from "@/context/language"
 import { usePermission } from "@/context/permission"
@@ -30,7 +27,6 @@ import {
 } from "@/context/settings"
 import { decode64 } from "@/utils/base64"
 import { playSoundById, SOUND_OPTIONS } from "@/utils/sound"
-import { Link } from "./link"
 import { SettingsList } from "./settings-list"
 
 let demoSoundState = {
@@ -39,11 +35,6 @@ let demoSoundState = {
   run: 0,
 }
 
-type ThemeOption = {
-  id: string
-  name: string
-}
-
 type ShellOption = {
   path: string
   name: string
@@ -88,7 +79,6 @@ export const SettingsGeneral: Component = () => {
   const language = useLanguage()
   const permission = usePermission()
   const platform = usePlatform()
-  const dialog = useDialog()
   const params = useParams()
   const settings = useSettings()
 
@@ -122,8 +112,6 @@ export const SettingsGeneral: Component = () => {
   }
   const desktop = createMemo(() => platform.platform === "desktop")
 
-  const themeOptions = createMemo<ThemeOption[]>(() => theme.ids().map((id) => ({ id, name: theme.name(id) })))
-
   const serverSync = useServerSync()
   const serverSdk = useServerSDK()
 
@@ -148,10 +136,6 @@ export const SettingsGeneral: Component = () => {
     { initialValue: false },
   )
 
-  onMount(() => {
-    void theme.loadThemes()
-  })
-
   const autoOption = { id: "auto", value: "", label: language.t("settings.general.row.shell.autoDefault") }
   const currentShell = createMemo(() => serverSync().data.config.shell ?? "")
 
@@ -250,50 +234,6 @@ export const SettingsGeneral: Component = () => {
     triggerVariant: "settings" as const,
   })
 
-  const InterfaceSection = () => (
-    <div class="flex flex-col gap-1">
-      <SettingsList>
-        <SettingsRow
-          title={
-            <span class="flex items-center gap-2">
-              {language.t("settings.general.row.newInterface.title")}
-              <Tag variant="accent">{language.t("settings.general.row.newInterface.badge")}</Tag>
-            </span>
-          }
-          description={language.t("settings.general.row.newInterface.description")}
-        >
-          <div data-action="settings-new-layout-designs">
-            <Switch
-              checked={settings.general.newLayoutDesigns()}
-              onChange={(checked) => {
-                settings.general.setNewLayoutDesigns(checked)
-                if (!checked) return
-                void import("@/components/settings-v2").then((module) => {
-                  void dialog.show(() => <module.DialogSettings />)
-                })
-              }}
-            />
-          </div>
-        </SettingsRow>
-      </SettingsList>
-    </div>
-  )
-
-  const InterfaceNoticeSection = () => (
-    <div class="flex flex-col gap-1">
-      <SettingsList>
-        <SettingsRow
-          title={language.t("settings.general.row.newInterfaceNotice.title")}
-          description={language.t("settings.general.row.newInterfaceNotice.description")}
-        >
-          <Button size="small" variant="ghost" onClick={settings.general.dismissNewInterfaceNotice}>
-            {language.t("settings.general.row.newInterfaceNotice.dismiss")}
-          </Button>
-        </SettingsRow>
-      </SettingsList>
-    </div>
-  )
-
   const GeneralSection = () => (
     <div class="flex flex-col gap-1">
       <SettingsList>
@@ -475,31 +415,6 @@ export const SettingsGeneral: Component = () => {
           />
         </SettingsRow>
 
-        <SettingsRow
-          title={language.t("settings.general.row.theme.title")}
-          description={
-            <>
-              {language.t("settings.general.row.theme.description")}{" "}
-              <Link href={`${DOCS_URL}/themes`}>{language.t("common.learnMore")}</Link>
-            </>
-          }
-        >
-          <Select
-            data-action="settings-theme"
-            options={themeOptions()}
-            current={themeOptions().find((o) => o.id === theme.themeId())}
-            value={(o) => o.id}
-            label={(o) => o.name}
-            onSelect={(option) => {
-              if (!option) return
-              theme.setTheme(option.id)
-            }}
-            variant="secondary"
-            size="small"
-            triggerVariant="settings"
-          />
-        </SettingsRow>
-
         <SettingsRow
           title={language.t("settings.general.row.uiFont.title")}
           description={language.t("settings.general.row.uiFont.description")}
@@ -746,14 +661,6 @@ export const SettingsGeneral: Component = () => {
       </div>
 
       <div class="flex flex-col gap-8 w-full">
-        <Show when={settings.general.layoutTransitionAvailable()}>
-          <InterfaceSection />
-        </Show>
-
-        <Show when={settings.general.newInterfaceNoticeVisible()}>
-          <InterfaceNoticeSection />
-        </Show>
-
         <GeneralSection />
 
         <AppearanceSection />
diff --git a/packages/app/src/components/settings-v2/general.tsx b/packages/app/src/components/settings-v2/general.tsx
index 6c75de5e9a..928e3a6dff 100644
--- a/packages/app/src/components/settings-v2/general.tsx
+++ b/packages/app/src/components/settings-v2/general.tsx
@@ -1,12 +1,10 @@
-import { Component, Show, createMemo, createResource, onMount } from "solid-js"
+import { Component, Show, createMemo, createResource } from "solid-js"
 import { createMediaQuery } from "@solid-primitives/media"
-import { DOCS_URL } from "@codev/brand"
 import { ButtonV2 } from "@opencode-ai/ui/v2/button-v2"
 import { SelectV2 } from "@opencode-ai/ui/v2/select-v2"
 import { Switch } from "@opencode-ai/ui/v2/switch-v2"
 import { TextInputV2 } from "@opencode-ai/ui/v2/text-input-v2"
 import { useTheme, type ColorScheme } from "@opencode-ai/ui/theme/context"
-import { useDialog } from "@opencode-ai/ui/context/dialog"
 import { useLanguage } from "@/context/language"
 import { usePermission } from "@/context/permission"
 import { usePlatform } from "@/context/platform"
@@ -26,10 +24,8 @@ import {
   useSettings,
 } from "@/context/settings"
 import { playSoundById, SOUND_OPTIONS } from "@/utils/sound"
-import { Link } from "../link"
 import { SettingsListV2 } from "./parts/list"
 import { SettingsRowV2 } from "./parts/row"
-import { LayoutRetirementNotice, LayoutTransitionToggle } from "./interface-transition"
 import "./settings-v2.css"
 
 let demoSoundState = {
@@ -38,11 +34,6 @@ let demoSoundState = {
   run: 0,
 }
 
-type ThemeOption = {
-  id: string
-  name: string
-}
-
 type ShellOption = {
   path: string
   name: string
@@ -89,7 +80,6 @@ export const SettingsGeneralV2: Component<{
   const language = useLanguage()
   const permission = usePermission()
   const platform = usePlatform()
-  const dialog = useDialog()
   const settings = useSettings()
   const serverSync = useServerSync()
   const serverSdk = useServerSDK()
@@ -120,8 +110,6 @@ export const SettingsGeneralV2: Component<{
   }
   const desktop = createMemo(() => platform.platform === "desktop")
 
-  const themeOptions = createMemo<ThemeOption[]>(() => theme.ids().map((id) => ({ id, name: theme.name(id) })))
-
   const [shells] = createResource(
     () =>
       serverSdk()
@@ -137,10 +125,6 @@ export const SettingsGeneralV2: Component<{
     { initialValue: false },
   )
 
-  onMount(() => {
-    void theme.loadThemes()
-  })
-
   const autoOption = { id: "auto", value: "", label: language.t("settings.general.row.shell.autoDefault") }
   const currentShell = createMemo(() => serverSync().data.config.shell ?? "")
 
@@ -228,31 +212,6 @@ export const SettingsGeneralV2: Component<{
     },
   })
 
-  const InterfaceSection = () => (
-    <LayoutTransitionToggle
-      title={language.t("settings.general.row.newInterface.title")}
-      badge={language.t("settings.general.row.newInterface.badge")}
-      description={language.t("settings.general.row.newInterface.description")}
-      checked={settings.general.newLayoutDesigns()}
-      onChange={(checked) => {
-        settings.general.setNewLayoutDesigns(checked)
-        if (checked) return
-        void import("@/components/dialog-settings").then((module) => {
-          void dialog.show(() => <module.DialogSettings />)
-        })
-      }}
-    />
-  )
-
-  const InterfaceNoticeSection = () => (
-    <LayoutRetirementNotice
-      title={language.t("settings.general.row.newInterfaceNotice.title")}
-      description={language.t("settings.general.row.newInterfaceNotice.description")}
-      dismiss={language.t("settings.general.row.newInterfaceNotice.dismiss")}
-      onDismiss={settings.general.dismissNewInterfaceNotice}
-    />
-  )
-
   const GeneralSection = () => (
     <div class="settings-v2-section">
       <SettingsListV2>
@@ -434,33 +393,6 @@ export const SettingsGeneralV2: Component<{
           />
         </SettingsRowV2>
 
-        <SettingsRowV2
-          title={language.t("settings.general.row.theme.title")}
-          description={
-            <>
-              {language.t("settings.general.row.theme.description")}{" "}
-              <Link class="settings-v2-link" href={`${DOCS_URL}/themes`}>
-                {language.t("common.learnMore")}
-              </Link>
-            </>
-          }
-        >
-          <SelectV2
-            appearance="inline"
-            data-action="settings-theme"
-            options={themeOptions()}
-            current={themeOptions().find((o) => o.id === theme.themeId())}
-            placement="bottom-end"
-            gutter={6}
-            value={(o) => o.id}
-            label={(o) => o.name}
-            onSelect={(option) => {
-              if (!option) return
-              theme.setTheme(option.id)
-            }}
-          />
-        </SettingsRowV2>
-
         <SettingsRowV2
           title={language.t("settings.general.row.uiFont.title")}
           description={language.t("settings.general.row.uiFont.description")}
@@ -692,14 +624,6 @@ export const SettingsGeneralV2: Component<{
       </div>
 
       <div class="settings-v2-tab-body">
-        <Show when={settings.general.layoutTransitionAvailable()}>
-          <InterfaceSection />
-        </Show>
-
-        <Show when={settings.general.newInterfaceNoticeVisible()}>
-          <InterfaceNoticeSection />
-        </Show>
-
         <GeneralSection />
 
         <AppearanceSection />
diff --git a/packages/app/src/components/settings-v2/interface-transition.stories.tsx b/packages/app/src/components/settings-v2/interface-transition.stories.tsx
deleted file mode 100644
index 0a48de9572..0000000000
--- a/packages/app/src/components/settings-v2/interface-transition.stories.tsx
+++ /dev/null
@@ -1,76 +0,0 @@
-// @ts-nocheck
-import { Show } from "solid-js"
-import { createStore } from "solid-js/store"
-import { LayoutRetirementNotice, LayoutTransitionToggle } from "./interface-transition"
-
-const copy = {
-  title: "New layout",
-  badge: "New",
-  description: "Use the new tabs and home layout. Switch between layouts for a limited time.",
-  noticeTitle: "You're now using new layout",
-  noticeDescription: "The previous layout is no longer available",
-  dismiss: "Dismiss",
-}
-
-function Frame(props) {
-  return <div class="w-[640px] max-w-full">{props.children}</div>
-}
-
-function ToggleExample(props) {
-  const [state, setState] = createStore({ checked: props.checked })
-  return (
-    <Frame>
-      <LayoutTransitionToggle
-        title={copy.title}
-        badge={copy.badge}
-        description={copy.description}
-        checked={state.checked}
-        onChange={(checked) => setState("checked", checked)}
-      />
-    </Frame>
-  )
-}
-
-function NoticeExample() {
-  const [state, setState] = createStore({ dismissed: false })
-  return (
-    <Frame>
-      <Show when={!state.dismissed} fallback={<span class="text-v2-text-text-muted">Notice dismissed</span>}>
-        <LayoutRetirementNotice
-          title={copy.noticeTitle}
-          description={copy.noticeDescription}
-          dismiss={copy.dismiss}
-          onDismiss={() => setState("dismissed", true)}
-        />
-      </Show>
-    </Frame>
-  )
-}
-
-export default {
-  title: "App/Settings/Layout transition",
-  id: "app-settings-layout-transition",
-  component: LayoutTransitionToggle,
-}
-
-export const NewLayoutEnabled = {
-  render: () => <ToggleExample checked />,
-}
-
-export const PreviousLayoutEnabled = {
-  render: () => <ToggleExample checked={false} />,
-}
-
-export const PreviousLayoutRetired = {
-  render: () => <NoticeExample />,
-}
-
-export const AllStates = {
-  render: () => (
-    <div class="flex flex-col gap-8">
-      <ToggleExample checked />
-      <ToggleExample checked={false} />
-      <NoticeExample />
-    </div>
-  ),
-}
diff --git a/packages/app/src/components/settings-v2/interface-transition.tsx b/packages/app/src/components/settings-v2/interface-transition.tsx
deleted file mode 100644
index 53bd980a54..0000000000
--- a/packages/app/src/components/settings-v2/interface-transition.tsx
+++ /dev/null
@@ -1,54 +0,0 @@
-import { Tag } from "@opencode-ai/ui/v2/badge-v2"
-import { ButtonV2 } from "@opencode-ai/ui/v2/button-v2"
-import { Switch } from "@opencode-ai/ui/v2/switch-v2"
-import { SettingsListV2 } from "./parts/list"
-import { SettingsRowV2 } from "./parts/row"
-
-export function LayoutTransitionToggle(props: {
-  title: string
-  badge: string
-  description: string
-  checked: boolean
-  onChange: (checked: boolean) => void
-}) {
-  return (
-    <div class="settings-v2-section">
-      <div class="settings-v2-interface-feature">
-        <SettingsListV2>
-          <SettingsRowV2
-            title={
-              <span class="flex items-center gap-2">
-                {props.title}
-                <Tag variant="accent">{props.badge}</Tag>
-              </span>
-            }
-            description={props.description}
-          >
-            <div data-action="settings-new-layout-designs">
-              <Switch checked={props.checked} onChange={props.onChange} />
-            </div>
-          </SettingsRowV2>
-        </SettingsListV2>
-      </div>
-    </div>
-  )
-}
-
-export function LayoutRetirementNotice(props: {
-  title: string
-  description: string
-  dismiss: string
-  onDismiss: () => void
-}) {
-  return (
-    <div class="settings-v2-section">
-      <SettingsListV2>
-        <SettingsRowV2 title={props.title} description={props.description}>
-          <ButtonV2 size="small" variant="ghost-muted" onClick={props.onDismiss}>
-            {props.dismiss}
-          </ButtonV2>
-        </SettingsRowV2>
-      </SettingsListV2>
-    </div>
-  )
-}
diff --git a/packages/app/src/context/settings.test.ts b/packages/app/src/context/settings.test.ts
index ba0161a6cd..36fbee0555 100644
--- a/packages/app/src/context/settings.test.ts
+++ b/packages/app/src/context/settings.test.ts
@@ -1,55 +1,7 @@
 import { describe, expect, test } from "bun:test"
-import {
-  isAppUpgrade,
-  layoutTransitionState,
-  maximumSunsetTimeout,
-  newLayoutDesignsDefault,
-  nextSunsetCheckDelay,
-  resolveNewLayoutDesigns,
-  shouldDisplayTabsToast,
-  shouldEnableNewLayout,
-} from "./settings"
-
-describe("layout transition", () => {
-  test("blank profiles default to the new layout", () => {
-    expect(newLayoutDesignsDefault).toBe(true)
-  })
-
-  test("hides the transition until a sunset is scheduled", () => {
-    expect(layoutTransitionState(false, true, false, false)).toEqual({ available: false, notice: false })
-  })
-
-  test("existing profiles can switch before sunset", () => {
-    expect(layoutTransitionState(true, true, false, false)).toEqual({ available: true, notice: false })
-  })
-
-  test("preserves explicit and default layout preferences", () => {
-    expect(resolveNewLayoutDesigns(false, false, true)).toBe(false)
-    expect(resolveNewLayoutDesigns(false, undefined, false)).toBe(false)
-    expect(resolveNewLayoutDesigns(false, undefined, true)).toBe(true)
-  })
-
-  test("sunset replaces the toggle with a dismissible notice", () => {
-    expect(layoutTransitionState(true, true, true, false)).toEqual({ available: false, notice: true })
-    expect(layoutTransitionState(true, true, true, true)).toEqual({ available: false, notice: false })
-    expect(resolveNewLayoutDesigns(true, false)).toBe(true)
-  })
-
-  test("caps checks for sunsets beyond the browser timeout limit", () => {
-    expect(nextSunsetCheckDelay(maximumSunsetTimeout + 1_000, 0)).toBe(maximumSunsetTimeout)
-    expect(nextSunsetCheckDelay(10_000, 9_000)).toBe(1_000)
-    expect(nextSunsetCheckDelay(9_000, 10_000)).toBe(0)
-  })
-
-  test("enables the new layout when upgrading from 1.17.19 or earlier", () => {
-    expect(shouldEnableNewLayout("v1.17.19", "1.17.20")).toBe(true)
-    expect(shouldEnableNewLayout("1.16.9", "2.0.0")).toBe(true)
-  })
-
-  test("enables the new layout when no previous version was recorded", () => {
-    expect(shouldEnableNewLayout(undefined, "1.17.20")).toBe(true)
-  })
+import { isAppUpgrade, shouldDisplayTabsToast } from "./settings"
 
+describe("launch classification", () => {
   test("detects upgrades only when a previous version is older", () => {
     expect(isAppUpgrade("1.17.19", "1.17.20")).toBe(true)
     expect(isAppUpgrade(undefined, "1.17.20")).toBe(false)
@@ -62,11 +14,4 @@ describe("layout transition", () => {
     expect(shouldDisplayTabsToast(undefined, "1.17.20", true)).toBe(true)
     expect(shouldDisplayTabsToast(undefined, "1.17.20", false)).toBe(false)
   })
-
-  test("does not enable the new layout without a qualifying upgrade", () => {
-    expect(shouldEnableNewLayout("1.17.19", "1.17.19")).toBe(false)
-    expect(shouldEnableNewLayout("1.17.20", "1.17.21")).toBe(false)
-    expect(shouldEnableNewLayout(undefined, "1.17.19")).toBe(false)
-    expect(shouldEnableNewLayout("dev", "1.17.20")).toBe(false)
-  })
 })
diff --git a/packages/app/src/context/settings.tsx b/packages/app/src/context/settings.tsx
index d892915301..f8d3fc4dad 100644
--- a/packages/app/src/context/settings.tsx
+++ b/packages/app/src/context/settings.tsx
@@ -56,11 +56,6 @@ export interface Settings {
 export const monoDefault = "System Mono"
 export const sansDefault = "System Sans"
 export const terminalDefault = "JetBrainsMono Nerd Font Mono"
-const legacyNewLayoutDesignsDefault = import.meta.env.VITE_CODEV_CHANNEL !== "prod"
-export const newLayoutDesignsDefault = true
-// Existing users can switch layouts until local midnight on this date. Set new Date(YYYY, M-1, D) to show.
-export const oldInterfaceSunset = new Date(2026, 8, 14)
-const newLayoutDesignsUpgradeCutoff = "1.17.19"
 
 function compareVersions(a: string, b: string) {
   const parse = (version: string) => {
@@ -89,38 +84,6 @@ export function shouldDisplayTabsToast(
   return isAppUpgrade(previous, current) || (!previous && existingInstall)
 }
 
-export function shouldEnableNewLayout(previous: string | undefined, current: string | undefined) {
-  if (!current) return false
-  const currentComparison = compareVersions(current, newLayoutDesignsUpgradeCutoff)
-  if (!previous) return currentComparison !== undefined && currentComparison > 0
-  if (!isAppUpgrade(previous, current)) return false
-  const previousComparison = compareVersions(previous, newLayoutDesignsUpgradeCutoff)
-  return (
-    previousComparison !== undefined &&
-    currentComparison !== undefined &&
-    previousComparison <= 0 &&
-    currentComparison > 0
-  )
-}
-
-export function layoutTransitionState(scheduled: boolean, eligible: boolean, retired: boolean, dismissed: boolean) {
-  return {
-    available: scheduled && eligible && !retired,
-    notice: scheduled && eligible && retired && !dismissed,
-  }
-}
-
-export const maximumSunsetTimeout = 2_147_483_647
-
-export function nextSunsetCheckDelay(sunset: number, now: number) {
-  return Math.min(Math.max(0, sunset - now), maximumSunsetTimeout)
-}
-
-export function resolveNewLayoutDesigns(retired: boolean, preference: boolean | undefined, fallback = true) {
-  if (retired) return true
-  return preference ?? fallback
-}
-
 const monoFallback =
   'ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace'
 const sansFallback = 'ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif'
@@ -227,7 +190,6 @@ export const { use: useSettings, provider: SettingsProvider } = createSimpleCont
     )
     const [launchState, setLaunchState] = createStore({
       classified: false,
-      migrationApplied: false,
       previous: undefined as string | undefined,
     })
     const showFileTree = withFallback(() => store.general?.showFileTree, defaultSettings.general.showFileTree)
@@ -237,52 +199,16 @@ export const { use: useSettings, provider: SettingsProvider } = createSimpleCont
       () => store.general?.showCustomAgents,
       defaultSettings.general.showCustomAgents,
     )
-    const sunset = oldInterfaceSunset
-    const [oldInterfaceRetired, setOldInterfaceRetired] = createSignal(sunset ? Date.now() >= sunset.getTime() : false)
     const layoutTransitionClassified = createMemo(() => typeof store.general?.layoutTransitionEligible === "boolean")
     const layoutTransitionEligible = withFallback(() => store.general?.layoutTransitionEligible, false)
-    const newInterfaceNoticeDismissed = withFallback(() => store.general?.newInterfaceNoticeDismissed, false)
-    const layoutUpgrade = createMemo(() =>
-      launchState.classified && !launchState.migrationApplied
-        ? shouldEnableNewLayout(launchState.previous, platform.version)
-        : false,
-    )
-    const layoutTransition = createMemo(() =>
-      layoutTransitionState(!!sunset, layoutTransitionEligible(), oldInterfaceRetired(), newInterfaceNoticeDismissed()),
-    )
-    const newLayoutDesigns = createMemo(() => {
-      if (layoutUpgrade()) return true
-      if (!ready() && !oldInterfaceRetired()) return legacyNewLayoutDesignsDefault
-      if (!layoutTransitionClassified()) {
-        return resolveNewLayoutDesigns(
-          oldInterfaceRetired(),
-          store.general?.newLayoutDesigns,
-          legacyNewLayoutDesignsDefault,
-        )
-      }
-      return resolveNewLayoutDesigns(
-        oldInterfaceRetired(),
-        store.general?.newLayoutDesigns,
-        layoutTransitionEligible() ? legacyNewLayoutDesignsDefault : newLayoutDesignsDefault,
-      )
-    })
+    // The legacy layout is retired in this fork: there is no toggle, no sunset
+    // countdown and no stored preference that can bring it back. Reading a
+    // constant rather than the persisted value means a profile carrying
+    // `newLayoutDesigns: false` — from an older build or a hand-edited store —
+    // still gets the new layout.
+    const newLayoutDesigns = createMemo(() => true)
     const visible = (preference: () => boolean) => createMemo(() => !newLayoutDesigns() || preference())
 
-    if (sunset && !oldInterfaceRetired()) {
-      const timeout = { current: undefined as ReturnType<typeof setTimeout> | undefined }
-      const checkSunset = () => {
-        if (Date.now() >= sunset.getTime()) {
-          setOldInterfaceRetired(true)
-          return
-        }
-        timeout.current = setTimeout(checkSunset, nextSunsetCheckDelay(sunset.getTime(), Date.now()))
-      }
-      checkSunset()
-      onCleanup(() => {
-        if (timeout.current !== undefined) clearTimeout(timeout.current)
-      })
-    }
-
     createEffect(() => {
       if (!launchReady() || launchState.classified) return
       setLaunchState({
@@ -293,14 +219,6 @@ export const { use: useSettings, provider: SettingsProvider } = createSimpleCont
       setLaunch("version", platform.version)
     })
 
-    createEffect(() => {
-      if (!ready() || !launchState.classified || launchState.migrationApplied) return
-      if (layoutUpgrade() && store.general?.newLayoutDesigns !== true) {
-        setStore("general", "newLayoutDesigns", true)
-      }
-      setLaunchState("migrationApplied", true)
-    })
-
     createEffect(() => {
       if (!ready() || !launchState.classified) return
       if (typeof store.general?.shouldDisplayTabsToast === "boolean") return
@@ -312,12 +230,6 @@ export const { use: useSettings, provider: SettingsProvider } = createSimpleCont
       )
     })
 
-    createEffect(() => {
-      if (!ready() || !oldInterfaceRetired()) return
-      if (store.general?.newLayoutDesigns === true) return
-      setStore("general", "newLayoutDesigns", true)
-    })
-
     createEffect(() => {
       if (typeof document === "undefined") return
       const root = document.documentElement
@@ -403,24 +315,18 @@ export const { use: useSettings, provider: SettingsProvider } = createSimpleCont
         setMobileTitlebarPosition(value: "top" | "bottom") {
           setStore("general", "mobileTitlebarPosition", value)
         },
+        // No setter: the layout is not a preference any more. Leaving one here
+        // as a no-op would let a caller look like it was switching layouts, so
+        // re-introducing the toggle has to be a compile error instead.
         newLayoutDesigns,
-        setNewLayoutDesigns(value: boolean) {
-          const next = oldInterfaceRetired() ? true : value
-          if (newLayoutDesigns() === next) return
-          setStore("general", "newLayoutDesigns", next)
-          if (typeof window !== "undefined") setTimeout(() => window.location.reload())
-        },
         layoutTransitionClassified,
+        // Still recorded because the tabs toast distinguishes a fresh profile
+        // from an existing install; it no longer gates any layout.
         setOldLayoutEligible(eligible: boolean) {
           const current = store.general?.layoutTransitionEligible
           if (typeof current === "boolean") return
           setStore("general", "layoutTransitionEligible", eligible)
         },
-        layoutTransitionAvailable: createMemo(() => ready() && layoutTransition().available),
-        newInterfaceNoticeVisible: createMemo(() => ready() && layoutTransition().notice),
-        dismissNewInterfaceNotice() {
-          setStore("general", "newInterfaceNoticeDismissed", true)
-        },
         shouldDisplayTabsToast: withFallback(() => store.general?.shouldDisplayTabsToast, false),
         dismissTabsToast() {
           setStore("general", "shouldDisplayTabsToast", false)
diff --git a/packages/app/src/pages/layout.tsx b/packages/app/src/pages/layout.tsx
index 67028fd089..7ab38e24af 100644
--- a/packages/app/src/pages/layout.tsx
+++ b/packages/app/src/pages/layout.tsx
@@ -136,7 +136,6 @@ export default function LegacyLayout(props: ParentProps) {
       dir: store[0].path.directory || dir,
     }
   })
-  const availableThemeEntries = createMemo(() => theme.ids().map((id) => [id, theme.themes()[id]] as const))
   const colorSchemeOrder: ColorScheme[] = ["system", "light", "dark"]
   const colorSchemeKey: Record<ColorScheme, "theme.scheme.system" | "theme.scheme.light" | "theme.scheme.dark"> = {
     system: "theme.scheme.system",
@@ -329,19 +328,6 @@ export default function LegacyLayout(props: ParentProps) {
     layout.mobileSidebar.hide()
   }
 
-  function cycleTheme(direction = 1) {
-    const ids = availableThemeEntries().map(([id]) => id)
-    if (ids.length === 0) return
-    const currentIndex = ids.indexOf(theme.themeId())
-    const nextIndex = currentIndex === -1 ? 0 : (currentIndex + direction + ids.length) % ids.length
-    const nextThemeId = ids[nextIndex]
-    theme.setTheme(nextThemeId)
-    showToast({
-      title: language.t("toast.theme.title"),
-      description: theme.name(nextThemeId),
-    })
-  }
-
   function cycleColorScheme(direction = 1) {
     const current = theme.colorScheme()
     const currentIndex = colorSchemeOrder.indexOf(current)
@@ -1018,13 +1004,6 @@ export default function LegacyLayout(props: ParentProps) {
           })
         },
       },
-      {
-        id: "theme.cycle",
-        title: language.t("command.theme.cycle"),
-        category: language.t("command.category.theme"),
-        keybind: "mod+shift+t",
-        onSelect: () => cycleTheme(1),
-      },
     ]
 
     Array.from({ length: 9 }, (_, i) => {
@@ -1041,19 +1020,6 @@ export default function LegacyLayout(props: ParentProps) {
       })
     })
 
-    for (const [id] of availableThemeEntries()) {
-      commands.push({
-        id: `theme.set.${id}`,
-        title: language.t("command.theme.set", { theme: theme.name(id) }),
-        category: language.t("command.category.theme"),
-        onSelect: () => theme.commitPreview(),
-        onHighlight: () => {
-          theme.previewTheme(id)
-          return () => theme.cancelPreview()
-        },
-      })
-    }
-
     commands.push({
       id: "theme.scheme.cycle",
       title: language.t("command.theme.scheme.cycle"),
diff --git a/packages/app/src/pages/session/composer/session-revert-dock.stories.tsx b/packages/app/src/pages/session/composer/session-revert-dock.stories.tsx
index ce3fd26b02..64c6ef0c1d 100644
--- a/packages/app/src/pages/session/composer/session-revert-dock.stories.tsx
+++ b/packages/app/src/pages/session/composer/session-revert-dock.stories.tsx
@@ -71,9 +71,6 @@ function Stage(props: { count: number }) {
         <button style={btn()} onClick={reset}>
           Reset ({props.count})
         </button>
-        <button style={btn(v2())} onClick={() => settings.general.setNewLayoutDesigns(!v2())}>
-          Layout: {v2() ? "v2" : "v1"}
-        </button>
       </div>
 
       {/* Reproduce the real composer stack: dock + card overlapping the dock's bottom by lift() = 18px */}
diff --git a/packages/app/src/theme-preload.test.ts b/packages/app/src/theme-preload.test.ts
index 00d7da2394..784eb7021f 100644
--- a/packages/app/src/theme-preload.test.ts
+++ b/packages/app/src/theme-preload.test.ts
@@ -34,13 +34,59 @@ describe("theme preload", () => {
     expect(document.getElementById("oc-theme-preload")).toBeNull()
   })
 
-  test("keeps cached css for non-default themes", () => {
+  test("drops a theme picked before the picker was removed", () => {
     localStorage.setItem("opencode-theme-id", "nightowl")
     localStorage.setItem("opencode-theme-css-light", "--background-base:#fff;")
 
     run()
 
-    expect(document.documentElement.dataset.theme).toBe("nightowl")
-    expect(document.getElementById("oc-theme-preload")?.textContent).toContain("--background-base:#fff;")
+    expect(document.documentElement.dataset.theme).toBe("oc-2")
+    expect(localStorage.getItem("opencode-theme-id")).toBe("oc-2")
+    expect(localStorage.getItem("opencode-theme-css-light")).toBeNull()
+    expect(document.getElementById("oc-theme-preload")).toBeNull()
+  })
+
+  test("leaves the shipped theme alone", () => {
+    localStorage.setItem("opencode-theme-id", "oc-2")
+    localStorage.setItem("opencode-color-scheme", "dark")
+
+    run()
+
+    expect(document.documentElement.dataset.theme).toBe("oc-2")
+    expect(document.documentElement.dataset.colorScheme).toBe("dark")
+    expect(document.getElementById("oc-theme-preload")).toBeNull()
+  })
+
+  test("records the shipped theme on a fresh profile", () => {
+    run()
+
+    expect(document.documentElement.dataset.theme).toBe("oc-2")
+    expect(localStorage.getItem("opencode-theme-id")).toBe("oc-2")
+    expect(document.documentElement.dataset.colorScheme).toBe("light")
+  })
+
+  test("follows the system scheme when none is stored", () => {
+    Object.defineProperty(window, "matchMedia", {
+      value: () => ({ matches: true }) as MediaQueryList,
+      configurable: true,
+    })
+
+    run()
+
+    expect(document.documentElement.dataset.colorScheme).toBe("dark")
+    expect(document.documentElement.style.backgroundColor).toBe("#080808")
+  })
+
+  // The migration has to happen here rather than after mount: the window
+  // paints before the app boots, so a leftover palette would show for a frame.
+  test("never injects cached palette css", () => {
+    localStorage.setItem("opencode-theme-id", "synthwave84")
+    localStorage.setItem("opencode-theme-css-light", "--background-base:#ff00ff;")
+    localStorage.setItem("opencode-theme-css-dark", "--background-base:#ff00ff;")
+
+    run()
+
+    expect(document.head.querySelector("style")).toBeNull()
+    expect(document.documentElement.style.backgroundColor).toBe("#fafafa")
   })
 })
diff --git a/packages/ui/src/theme/context.test.ts b/packages/ui/src/theme/context.test.ts
new file mode 100644
index 0000000000..025a46e100
--- /dev/null
+++ b/packages/ui/src/theme/context.test.ts
@@ -0,0 +1,34 @@
+import { describe, expect, test } from "bun:test"
+import { normalizeThemeID, SHIPPED_THEME_ID } from "./context"
+
+// This is the chokepoint the whole single-theme guarantee rests on: provider
+// init, the mount-time migration, `load`, the cross-tab storage listener,
+// `setTheme` and `previewTheme` all resolve their id through it. If it ever
+// starts passing an id through again, the picker is effectively back.
+describe("normalizeThemeID", () => {
+  test("resolves a theme picked before the picker was removed", () => {
+    expect(normalizeThemeID("dracula")).toBe(SHIPPED_THEME_ID)
+    expect(normalizeThemeID("nightowl")).toBe(SHIPPED_THEME_ID)
+    expect(normalizeThemeID("opencode")).toBe(SHIPPED_THEME_ID)
+  })
+
+  test("resolves an id another tab could write", () => {
+    // The storage listener feeds it whatever landed in localStorage, which is
+    // not necessarily a theme the app ever shipped.
+    expect(normalizeThemeID("not-a-theme")).toBe(SHIPPED_THEME_ID)
+    expect(normalizeThemeID("")).toBe(SHIPPED_THEME_ID)
+  })
+
+  test("still covers the legacy oc-1 profiles upstream migrated", () => {
+    expect(normalizeThemeID("oc-1")).toBe(SHIPPED_THEME_ID)
+  })
+
+  test("resolves a missing id", () => {
+    expect(normalizeThemeID(null)).toBe(SHIPPED_THEME_ID)
+    expect(normalizeThemeID(undefined)).toBe(SHIPPED_THEME_ID)
+  })
+
+  test("leaves the shipped id alone", () => {
+    expect(normalizeThemeID(SHIPPED_THEME_ID)).toBe(SHIPPED_THEME_ID)
+  })
+})
diff --git a/packages/ui/src/theme/context.tsx b/packages/ui/src/theme/context.tsx
index f225ee33ac..70068cfea6 100644
--- a/packages/ui/src/theme/context.tsx
+++ b/packages/ui/src/theme/context.tsx
@@ -84,8 +84,17 @@ const names: Record<string, string> = {
 }
 const oc2Theme = oc2ThemeJson as DesktopTheme
 
-function normalize(id: string | null | undefined) {
-  return id === "oc-1" ? "oc-2" : id
+export const SHIPPED_THEME_ID = "oc-2"
+
+// The app ships a single theme, so every id resolves to SHIPPED_THEME_ID. This
+// is the one chokepoint every entry point already passes through — init, the
+// mount-time migration, `load`, the cross-tab storage event, `setTheme` and
+// `previewTheme` — so a value persisted before the picker was removed, or
+// written by another tab, can never bring a second palette back. Light and
+// dark are the `colorScheme` axis, not separate themes. Exported so the
+// invariant is covered by a test rather than only by its call sites.
+export function normalizeThemeID(_id: string | null | undefined) {
+  return SHIPPED_THEME_ID
 }
 
 function read(key: string) {
@@ -177,7 +186,7 @@ export const { use: useTheme, provider: ThemeProvider } = createSimpleContext({
     defaultTheme?: string
     onThemeApplied?: (theme: DesktopTheme, mode: "light" | "dark", scheme: ColorScheme) => void
   }) => {
-    const themeId = normalize(read(STORAGE_KEYS.THEME_ID) ?? props.defaultTheme) ?? "oc-2"
+    const themeId = normalizeThemeID(read(STORAGE_KEYS.THEME_ID) ?? props.defaultTheme) ?? "oc-2"
     const colorScheme = (read(STORAGE_KEYS.COLOR_SCHEME) as ColorScheme | null) ?? "system"
     const mode = colorScheme === "system" ? getSystemMode() : colorScheme
     const [store, setStore] = createStore({
@@ -194,7 +203,7 @@ export const { use: useTheme, provider: ThemeProvider } = createSimpleContext({
     const loads = new Map<string, Promise<DesktopTheme | undefined>>()
 
     const load = (id: string) => {
-      const next = normalize(id)
+      const next = normalizeThemeID(id)
       if (!next) return Promise.resolve(undefined)
       const hit = store.themes[next]
       if (hit) return Promise.resolve(hit)
@@ -220,20 +229,15 @@ export const { use: useTheme, provider: ThemeProvider } = createSimpleContext({
       props.onThemeApplied?.(theme, mode, scheme)
     }
 
-    const ids = () => {
-      const extra = Object.keys(store.themes)
-        .filter((id) => !knownThemes().has(id))
-        .sort()
-      const all = themeIDs()
-      if (extra.length === 0) return all
-      return [...all, ...extra]
-    }
+    // Only the shipped theme is selectable, so neither the bundled palettes nor
+    // anything a plugin registered is listed or loaded.
+    const ids = () => ["oc-2"]
 
-    const loadThemes = () => Promise.all(themeIDs().map(load)).then(() => store.themes)
+    const loadThemes = () => load("oc-2").then(() => store.themes)
 
     const onStorage = (e: StorageEvent) => {
       if (e.key === STORAGE_KEYS.THEME_ID && e.newValue) {
-        const next = normalize(e.newValue)
+        const next = normalizeThemeID(e.newValue)
         if (!next) return
         if (next !== "oc-2" && !knownThemes().has(next) && !store.themes[next]) return
         setStore("themeId", next)
@@ -263,7 +267,7 @@ export const { use: useTheme, provider: ThemeProvider } = createSimpleContext({
       makeEventListener(mediaQuery, "change", onMedia)
 
       const rawTheme = read(STORAGE_KEYS.THEME_ID)
-      const savedTheme = normalize(rawTheme ?? props.defaultTheme) ?? "oc-2"
+      const savedTheme = normalizeThemeID(rawTheme ?? props.defaultTheme) ?? "oc-2"
       const savedScheme = (read(STORAGE_KEYS.COLOR_SCHEME) as ColorScheme | null) ?? "system"
       if (rawTheme && rawTheme !== savedTheme) {
         write(STORAGE_KEYS.THEME_ID, savedTheme)
@@ -285,7 +289,7 @@ export const { use: useTheme, provider: ThemeProvider } = createSimpleContext({
     })
 
     const setTheme = (id: string) => {
-      const next = normalize(id)
+      const next = normalizeThemeID(id)
       if (!next) {
         console.warn(`Theme "${id}" not found`)
         return
@@ -325,7 +329,7 @@ export const { use: useTheme, provider: ThemeProvider } = createSimpleContext({
       setColorScheme,
       registerTheme: (theme: DesktopTheme) => setStore("themes", theme.id, theme),
       previewTheme: (id: string) => {
-        const next = normalize(id)
+        const next = normalizeThemeID(id)
         if (!next) return
         if (next !== "oc-2" && !knownThemes().has(next) && !store.themes[next]) return
         setStore("previewThemeId", next)