diff --git a/desktop/index.html b/desktop/index.html
index c219f214d..4b58bd432 100644
--- a/desktop/index.html
+++ b/desktop/index.html
@@ -15,10 +15,10 @@
       The inline script below reads the cached theme background (same
       `buzz-theme-cache` entry ThemeProvider writes) and applies it synchronously
       so the boot color matches the themed loading gate — no black flash on light
-      themes. On the first-ever launch (no cache yet) it seeds the `dark` class
-      synchronously so the setup gate reads the dark `:root` vars instead of the
-      light Catppuccin-Latte default, matching the dark `houston` theme
-      ThemeProvider applies moments later — no light flash before it loads.
+      themes. On the first-ever launch (no cache yet) it seeds the light/dark
+      class from the OS color scheme, matching the Buzz theme in System mode
+      that ThemeProvider applies moments later — no wrong-scheme flash before
+      it loads.
     -->
     <style>
       html {
@@ -31,10 +31,16 @@
         try {
           cached = window.localStorage.getItem("buzz-theme-cache");
           if (!cached) {
-            // No stored theme: the default theme (`houston`) is dark, so seed
-            // the `dark` class now. Otherwise the setup gate would paint from
-            // the light `:root` vars until ThemeProvider loads asynchronously.
-            document.documentElement.classList.add("dark");
+            // No stored theme: the default is Buzz following the OS scheme,
+            // so seed the matching class (and backdrop) now. Otherwise the
+            // setup gate would paint the wrong scheme until ThemeProvider
+            // loads asynchronously.
+            if (window.matchMedia("(prefers-color-scheme: dark)").matches) {
+              document.documentElement.classList.add("dark");
+            } else {
+              document.documentElement.classList.add("light");
+              document.documentElement.style.backgroundColor = "#fff";
+            }
             return;
           }
           parsed = JSON.parse(cached);
diff --git a/desktop/src/features/onboarding/ui/OnboardingFlow.tsx b/desktop/src/features/onboarding/ui/OnboardingFlow.tsx
index cdd0fd07a..e507f4b61 100644
--- a/desktop/src/features/onboarding/ui/OnboardingFlow.tsx
+++ b/desktop/src/features/onboarding/ui/OnboardingFlow.tsx
@@ -12,19 +12,11 @@ import {
   importIdentity,
   persistCurrentIdentity,
 } from "@/shared/api/tauriIdentity";
-import {
-  ACCENT_STORAGE_KEY,
-  NEUTRAL_ACCENT,
-  THEME_STORAGE_KEY,
-  useTheme,
-} from "@/shared/theme/ThemeProvider";
 import { useSystemColorScheme } from "@/shared/theme/useSystemColorScheme";
-import { ONBOARDING_DEFAULT_THEME_NAME } from "@/shared/theme/theme-loader";
 import { Button } from "@/shared/ui/button";
 import { StartupWindowDragRegion } from "@/shared/ui/StartupWindowDragRegion";
 import { StepProgress } from "@/shared/ui/step-progress";
 import { AvatarStep } from "./AvatarStep";
-import { BackupStep } from "./BackupStep";
 import { MembershipDenied } from "./MembershipDenied";
 import { NostrKeyImportForm } from "./NostrKeyImportForm";
 import { useCommunities } from "@/features/communities/useCommunities";
@@ -34,8 +26,6 @@ import {
   OnboardingSlideTransition,
 } from "./OnboardingSlideTransition";
 import { ProfileStep } from "./ProfileStep";
-import { SetupStep } from "./SetupStep";
-import { ThemeStep, preloadThemePreviewVars } from "./ThemeStep";
 import type {
   OnboardingActions,
   OnboardingPage,
@@ -190,36 +180,6 @@ export function OnboardingFlow({
   const [transitionDirection, setTransitionDirection] =
     React.useState<OnboardingTransitionDirection>("forward");
   const systemColorScheme = useSystemColorScheme();
-  const { accentColor, setAccentColor, setTheme, themeName } = useTheme();
-
-  const ensureThemeStepDefaults = React.useCallback(() => {
-    const hasStoredTheme =
-      window.localStorage.getItem(THEME_STORAGE_KEY) !== null;
-    const hasStoredAccent =
-      window.localStorage.getItem(ACCENT_STORAGE_KEY) !== null;
-
-    if (!hasStoredTheme && themeName !== ONBOARDING_DEFAULT_THEME_NAME) {
-      setTheme(ONBOARDING_DEFAULT_THEME_NAME);
-    }
-
-    if (!hasStoredAccent && accentColor !== NEUTRAL_ACCENT) {
-      setAccentColor(NEUTRAL_ACCENT);
-    }
-  }, [accentColor, setAccentColor, setTheme, themeName]);
-
-  React.useEffect(() => {
-    if (
-      currentPage === "profile" ||
-      currentPage === "backup" ||
-      currentPage === "avatar"
-    ) {
-      void preloadThemePreviewVars().catch(() => undefined);
-    }
-
-    if (currentPage === "avatar") {
-      ensureThemeStepDefaults();
-    }
-  }, [currentPage, ensureThemeStepDefaults]);
 
   const resetProfileSaveError = React.useCallback(() => {
     profileUpdateMutation.reset();
@@ -236,20 +196,6 @@ export function OnboardingFlow({
     [resetProfileSaveError],
   );
 
-  const showSetupPage = React.useCallback(() => {
-    setTransitionDirection("forward");
-    setCurrentPage("setup");
-  }, []);
-
-  const showThemePage = React.useCallback(
-    (direction: OnboardingTransitionDirection = "forward") => {
-      ensureThemeStepDefaults();
-      setTransitionDirection(direction);
-      setCurrentPage("theme");
-    },
-    [ensureThemeStepDefaults],
-  );
-
   const showAvatarPage = React.useCallback(
     (direction: OnboardingTransitionDirection = "forward") => {
       setTransitionDirection(direction);
@@ -430,8 +376,7 @@ export function OnboardingFlow({
   const pageIndex = activeSteps.indexOf(normalizedPage);
   const currentStep = pageIndex >= 0 ? pageIndex + STEP_OFFSET : STEP_OFFSET;
   const totalOnboardingSteps = activeSteps.length;
-  const hideFixedProgressOnCompact =
-    currentPage === "avatar" || currentPage === "theme";
+  const hideFixedProgressOnCompact = currentPage === "avatar";
 
   // Swapping the identity changes the pubkey, which remounts this flow
   // (keyed on pubkey in App.tsx) and re-runs the onboarding gate: the new
@@ -502,27 +447,14 @@ export function OnboardingFlow({
   return (
     <>
       <div
-        className={`buzz-startup-shell flex items-start justify-center overflow-y-auto bg-background px-4 py-8 text-foreground ${
-          currentPage === "profile" ||
-          currentPage === "backup" ||
-          currentPage === "avatar" ||
-          currentPage === "key-import"
-            ? "buzz-onboarding-neutral-theme"
-            : ""
-        }`}
+        className="buzz-onboarding-neutral-theme buzz-startup-shell flex items-start justify-center overflow-y-auto bg-background px-4 py-8 text-foreground"
         data-testid="onboarding-gate"
         data-system-color-scheme={systemColorScheme}
       >
         <StartupWindowDragRegion />
         <div
           className={`relative my-auto flex w-full flex-col items-center text-center ${
-            currentPage === "theme"
-              ? "max-w-[1180px]"
-              : currentPage === "avatar"
-                ? "max-w-[1080px]"
-                : currentPage === "setup"
-                  ? "max-w-[920px]"
-                  : "max-w-[500px]"
+            currentPage === "avatar" ? "max-w-[1080px]" : "max-w-[500px]"
           }`}
         >
           <OnboardingSlideTransition
@@ -643,15 +575,7 @@ export function OnboardingFlow({
                 onImport={importExistingKey}
               />
             </OnboardingSlideTransition>
-          ) : currentPage === "backup" ? (
-            <BackupStep
-              currentStep={currentStep}
-              direction={transitionDirection}
-              onBack={showProfilePage}
-              onNext={() => showAvatarPage()}
-              totalSteps={totalOnboardingSteps}
-            />
-          ) : currentPage === "avatar" ? (
+          ) : (
             <AvatarStep
               actions={{
                 advanceWithoutSaving: complete,
@@ -669,22 +593,6 @@ export function OnboardingFlow({
               state={avatarStepState}
               totalSteps={totalOnboardingSteps}
             />
-          ) : currentPage === "theme" ? (
-            <ThemeStep
-              actions={{
-                skip: showSetupPage,
-                submit: showSetupPage,
-              }}
-              direction={transitionDirection}
-            />
-          ) : (
-            <SetupStep
-              actions={{
-                back: () => showThemePage("backward"),
-                complete,
-              }}
-              direction={transitionDirection}
-            />
           )}
         </div>
       </div>
diff --git a/desktop/src/features/onboarding/ui/ThemeStep.tsx b/desktop/src/features/onboarding/ui/ThemeStep.tsx
deleted file mode 100644
index 9a77dcf3f..000000000
--- a/desktop/src/features/onboarding/ui/ThemeStep.tsx
+++ /dev/null
@@ -1,311 +0,0 @@
-import { Check } from "lucide-react";
-import * as React from "react";
-
-import {
-  ACCENT_COLORS,
-  ACCENT_STORAGE_KEY,
-  NEUTRAL_ACCENT,
-  THEME_STORAGE_KEY,
-  useTheme,
-} from "@/shared/theme/ThemeProvider";
-import {
-  ONBOARDING_DEFAULT_THEME_NAME,
-  SYNTAX_THEMES,
-  type SyntaxThemeName,
-} from "@/shared/theme/theme-loader";
-import {
-  ThemePreviewFrame,
-  type ThemePreviewVars,
-} from "@/shared/theme/ThemePreviewFrame";
-import {
-  getThemeFallbackPreviewVars,
-  useThemePreviewVars,
-  withAccentPreviewVars,
-} from "@/shared/theme/useThemePreviewVars";
-import { cn } from "@/shared/lib/cn";
-import { Button } from "@/shared/ui/button";
-import { StepProgress } from "@/shared/ui/step-progress";
-import {
-  type OnboardingTransitionDirection,
-  OnboardingSlideTransition,
-} from "./OnboardingSlideTransition";
-import type { ThemeStepActions } from "./types";
-
-type ThemeStepProps = {
-  actions: ThemeStepActions;
-  direction: OnboardingTransitionDirection;
-};
-
-const GRADUAL_BLUR_LEVELS = [0.5, 1.25, 2.5, 4.5, 7, 10] as const;
-const THEME_TILE_WIDTH = 174;
-const THEME_TILE_HEIGHT = 160;
-const THEME_TILE_GAP = 12;
-const THEME_VISIBLE_ROW_COUNT = 2;
-const THEME_ROW_PEEK_HEIGHT = 48;
-const THEME_SCROLL_MAX_HEIGHT =
-  THEME_TILE_HEIGHT * THEME_VISIBLE_ROW_COUNT +
-  THEME_TILE_GAP * THEME_VISIBLE_ROW_COUNT +
-  THEME_ROW_PEEK_HEIGHT;
-
-function contrastColorForHex(hex: string) {
-  const match = /^#?([a-f\d]{2})([a-f\d]{2})([a-f\d]{2})$/i.exec(hex);
-  if (!match) {
-    return "#ffffff";
-  }
-
-  const r = Number.parseInt(match[1], 16);
-  const g = Number.parseInt(match[2], 16);
-  const b = Number.parseInt(match[3], 16);
-  const luminance = (0.299 * r + 0.587 * g + 0.114 * b) / 255;
-  return luminance > 0.5 ? "#000000" : "#ffffff";
-}
-
-function formatThemeLabel(name: string): string {
-  return name
-    .split("-")
-    .map((word) => word.charAt(0).toUpperCase() + word.slice(1))
-    .join(" ");
-}
-
-function getOrderedThemes() {
-  return [
-    ONBOARDING_DEFAULT_THEME_NAME,
-    ...SYNTAX_THEMES.filter((name) => name !== ONBOARDING_DEFAULT_THEME_NAME),
-  ];
-}
-
-export { preloadThemePreviewVars } from "@/shared/theme/useThemePreviewVars";
-
-function GradualBottomBlur() {
-  return (
-    <div
-      aria-hidden="true"
-      className="pointer-events-none absolute inset-x-0 -bottom-4 z-10 h-28 overflow-hidden"
-    >
-      {GRADUAL_BLUR_LEVELS.map((blur, index) => {
-        const transparentStop = 96 - index * 11;
-        const solidStop = Math.max(0, transparentStop - 28);
-        const maskImage = `linear-gradient(to top, black 0%, black ${solidStop}%, transparent ${transparentStop}%)`;
-
-        return (
-          <div
-            className="absolute inset-0"
-            key={blur}
-            style={{
-              WebkitBackdropFilter: `blur(${blur}px)`,
-              WebkitMaskImage: maskImage,
-              backdropFilter: `blur(${blur}px)`,
-              maskImage,
-            }}
-          />
-        );
-      })}
-      <div
-        className="absolute inset-0"
-        style={{
-          background:
-            "linear-gradient(to top, hsl(var(--background)) 0%, hsl(var(--background) / 0.64) 30%, hsl(var(--background) / 0.18) 64%, transparent 100%)",
-        }}
-      />
-    </div>
-  );
-}
-
-function ThemeTile({
-  isActive,
-  name,
-  onSelect,
-  vars,
-}: {
-  isActive: boolean;
-  name: SyntaxThemeName;
-  onSelect: () => void;
-  vars: ThemePreviewVars | null;
-}) {
-  return (
-    <button
-      aria-pressed={isActive}
-      className={cn(
-        "group flex w-[174px] min-w-0 flex-col rounded-lg border bg-background/70 p-2 text-left transition-colors focus-visible:outline-hidden focus-visible:ring-2 focus-visible:ring-ring",
-        isActive
-          ? "border-primary text-foreground shadow-sm"
-          : "border-border/70 text-muted-foreground hover:border-border hover:bg-accent/70 hover:text-accent-foreground",
-      )}
-      data-testid={`onboarding-theme-option-${name}`}
-      onClick={onSelect}
-      type="button"
-    >
-      <ThemePreviewFrame vars={vars} />
-
-      <div className="mt-2 flex min-h-6 items-center gap-2 px-1">
-        <span className="min-w-0 flex-1 truncate text-sm font-medium">
-          {formatThemeLabel(name)}
-        </span>
-        {isActive ? <Check className="h-4 w-4 shrink-0 text-primary" /> : null}
-      </div>
-    </button>
-  );
-}
-
-function AccentColorPicker({
-  accentColor,
-  onSelect,
-}: {
-  accentColor: string;
-  onSelect: (value: string) => void;
-}) {
-  return (
-    <div className="mx-auto mt-6 w-fit max-w-full rounded-xl bg-muted p-3">
-      <div className="flex flex-wrap items-center justify-center gap-2">
-        {ACCENT_COLORS.map((color) => {
-          const isNeutral = color.value === NEUTRAL_ACCENT;
-          const isSelected = accentColor === color.value;
-          const swatchBackground = isNeutral
-            ? "hsl(var(--foreground))"
-            : color.value;
-          const selectedRingColor = isNeutral
-            ? "hsl(var(--background))"
-            : contrastColorForHex(color.value);
-
-          return (
-            <button
-              aria-label={`Use ${color.name} accent color`}
-              aria-pressed={isSelected}
-              className="relative h-9 w-9 rounded-full border border-border transition-transform duration-200 ease-out hover:scale-[1.12] focus-visible:scale-[1.12] focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-ring"
-              data-testid={`onboarding-accent-color-${color.name.toLowerCase()}`}
-              key={color.value}
-              onClick={() => onSelect(color.value)}
-              style={{ background: swatchBackground }}
-              title={color.name}
-              type="button"
-            >
-              {isSelected ? (
-                <span
-                  className="absolute inset-1 rounded-full border-[3px]"
-                  style={{
-                    borderColor: selectedRingColor,
-                  }}
-                />
-              ) : null}
-            </button>
-          );
-        })}
-      </div>
-    </div>
-  );
-}
-
-export function ThemeStep({ actions, direction }: ThemeStepProps) {
-  const { skip, submit } = actions;
-  const { accentColor, setAccentColor, setTheme, themeName } = useTheme();
-  const previewVarsByTheme = useThemePreviewVars();
-  const orderedThemes = React.useMemo(() => getOrderedThemes(), []);
-
-  React.useEffect(() => {
-    const hasStoredTheme =
-      window.localStorage.getItem(THEME_STORAGE_KEY) !== null;
-    const hasStoredAccent =
-      window.localStorage.getItem(ACCENT_STORAGE_KEY) !== null;
-
-    if (!hasStoredTheme && themeName !== ONBOARDING_DEFAULT_THEME_NAME) {
-      setTheme(ONBOARDING_DEFAULT_THEME_NAME);
-    }
-
-    if (!hasStoredAccent && accentColor !== NEUTRAL_ACCENT) {
-      setAccentColor(NEUTRAL_ACCENT);
-    }
-  }, [accentColor, setAccentColor, setTheme, themeName]);
-
-  return (
-    <OnboardingSlideTransition
-      className="flex w-full flex-col items-center pb-40 text-center lg:pb-0"
-      data-testid="onboarding-page-theme"
-      direction={direction}
-      transitionKey={`theme-${direction}`}
-    >
-      <div className="grid w-full max-w-[1180px] items-start gap-12 lg:grid-cols-[minmax(260px,320px)_minmax(0,760px)] lg:gap-14">
-        <div className="flex w-full flex-col items-center text-center lg:items-start lg:text-left">
-          <div className="w-full max-w-[360px]">
-            <h1 className="text-3xl font-semibold text-foreground">
-              Pick a theme
-            </h1>
-            <p className="mt-3 text-sm leading-6 text-muted-foreground">
-              Choose a look that makes Buzz feel like yours.
-            </p>
-          </div>
-        </div>
-
-        <div className="w-full">
-          <div className="relative w-full">
-            <div
-              className="overflow-y-auto pb-20 [scrollbar-width:none] [&::-webkit-scrollbar]:hidden"
-              style={{
-                maxHeight: `min(60dvh, ${THEME_SCROLL_MAX_HEIGHT}px)`,
-              }}
-            >
-              <div
-                className="grid justify-center gap-3"
-                style={{
-                  gridTemplateColumns: `repeat(auto-fill, ${THEME_TILE_WIDTH}px)`,
-                }}
-              >
-                {orderedThemes.map((name) => {
-                  const vars = withAccentPreviewVars(
-                    previewVarsByTheme[name] ??
-                      getThemeFallbackPreviewVars(name),
-                    accentColor,
-                  );
-
-                  return (
-                    <ThemeTile
-                      isActive={themeName === name}
-                      key={name}
-                      name={name}
-                      onSelect={() => setTheme(name)}
-                      vars={vars}
-                    />
-                  );
-                })}
-              </div>
-            </div>
-            <GradualBottomBlur />
-          </div>
-
-          <AccentColorPicker
-            accentColor={accentColor}
-            onSelect={setAccentColor}
-          />
-
-          <div className="mt-10 flex w-full flex-col gap-3 lg:mx-auto lg:max-w-[500px] max-lg:fixed max-lg:inset-x-0 max-lg:bottom-0 max-lg:z-40 max-lg:mt-0 max-lg:max-w-none max-lg:border-t max-lg:border-border max-lg:bg-background max-lg:p-4 max-lg:pb-[max(1rem,env(safe-area-inset-bottom))]">
-            <Button
-              className="h-10 w-full"
-              data-testid="onboarding-next"
-              onClick={submit}
-              type="button"
-            >
-              Next
-            </Button>
-
-            <Button
-              className="h-10 w-full text-muted-foreground hover:text-accent-foreground"
-              data-testid="onboarding-skip"
-              onClick={skip}
-              type="button"
-              variant="ghost"
-            >
-              Skip
-            </Button>
-
-            <StepProgress
-              activeSegmentClassName="bg-primary"
-              className="mt-1 lg:hidden"
-              completeSegmentClassName="bg-primary/35"
-              currentStep={4}
-              inactiveSegmentClassName="bg-muted-foreground/25"
-            />
-          </div>
-        </div>
-      </div>
-    </OnboardingSlideTransition>
-  );
-}
diff --git a/desktop/src/features/onboarding/ui/onboardingFlowSteps.test.mjs b/desktop/src/features/onboarding/ui/onboardingFlowSteps.test.mjs
index 3841b4a1c..164c1e488 100644
--- a/desktop/src/features/onboarding/ui/onboardingFlowSteps.test.mjs
+++ b/desktop/src/features/onboarding/ui/onboardingFlowSteps.test.mjs
@@ -1,109 +1,55 @@
 /**
- * Tests for the onboarding step-count and routing logic that was added for the
- * key-backup feature. These are pure-logic tests — no React rendering needed.
+ * Tests for the onboarding step-count logic and the BackupStep gating helper
+ * (BackupStep now runs in the machine onboarding flow). These are pure-logic
+ * tests — no React rendering needed.
  */
 import assert from "node:assert/strict";
 import test from "node:test";
 
 import { backupNextDisabled } from "./BackupStep.tsx";
 
-// Mirrors the FRESH_STEPS / IMPORT_STEPS arrays in OnboardingFlow.tsx.
-// key-import is normalised to "profile" before the indexOf lookup.
-const FRESH_STEPS = ["profile", "backup", "avatar", "theme", "setup"];
-const IMPORT_STEPS = ["profile", "avatar", "theme", "setup"];
-const STEP_OFFSET = 2;
+// Mirrors the activeSteps array in OnboardingFlow.tsx. The relay-scoped flow
+// owns only the community profile: profile → avatar. key-import is normalised
+// to "profile" before the indexOf lookup.
+const ACTIVE_STEPS = ["profile", "avatar"];
+const STEP_OFFSET = 1;
 
 /**
- * Mirrors the currentStep derivation in OnboardingFlow.tsx.
- * Fresh path: profile(2) → backup(3) → avatar(4) → theme(5) → setup(6)
- * Imported path: profile(2) → avatar(3) → theme(4) → setup(5)
+ * Mirrors the currentStep derivation in OnboardingFlow.tsx:
+ * profile(1) → avatar(2).
  */
-function computeCurrentStep(page, identityWasImported) {
-  const steps = identityWasImported ? IMPORT_STEPS : FRESH_STEPS;
+function computeCurrentStep(page) {
   const normalizedPage = page === "key-import" ? "profile" : page;
-  const idx = steps.indexOf(normalizedPage);
+  const idx = ACTIVE_STEPS.indexOf(normalizedPage);
   return idx >= 0 ? idx + STEP_OFFSET : STEP_OFFSET;
 }
 
-function computeTotalSteps(identityWasImported) {
-  const steps = identityWasImported ? IMPORT_STEPS : FRESH_STEPS;
-  return steps.length + 1;
+function computeTotalSteps() {
+  return ACTIVE_STEPS.length;
 }
 
 // ---------------------------------------------------------------------------
-// Total step count
+// Step count and numbering
 // ---------------------------------------------------------------------------
 
-test("totalSteps_is_5_when_identity_was_imported", () => {
-  assert.equal(computeTotalSteps(true), 5);
+test("totalSteps_is_2", () => {
+  assert.equal(computeTotalSteps(), 2);
 });
 
-test("totalSteps_is_6_on_fresh_key_path", () => {
-  assert.equal(computeTotalSteps(false), 6);
+test("currentStep_profile_is_1", () => {
+  assert.equal(computeCurrentStep("profile"), 1);
 });
 
-// ---------------------------------------------------------------------------
-// Step numbers — fresh path (6 steps)
-// ---------------------------------------------------------------------------
-
-test("currentStep_profile_is_2_on_fresh_path", () => {
-  assert.equal(computeCurrentStep("profile", false), 2);
+test("currentStep_key_import_is_1", () => {
+  assert.equal(computeCurrentStep("key-import"), 1);
 });
 
-test("currentStep_key_import_is_2_on_fresh_path", () => {
-  assert.equal(computeCurrentStep("key-import", false), 2);
+test("currentStep_avatar_is_2", () => {
+  assert.equal(computeCurrentStep("avatar"), 2);
 });
 
-test("currentStep_backup_is_3_on_fresh_path", () => {
-  assert.equal(computeCurrentStep("backup", false), 3);
-});
-
-test("currentStep_avatar_is_4_on_fresh_path", () => {
-  assert.equal(computeCurrentStep("avatar", false), 4);
-});
-
-test("currentStep_theme_is_5_on_fresh_path", () => {
-  assert.equal(computeCurrentStep("theme", false), 5);
-});
-
-test("currentStep_setup_is_6_on_fresh_path", () => {
-  assert.equal(computeCurrentStep("setup", false), 6);
-});
-
-// ---------------------------------------------------------------------------
-// Step numbers — imported key path (5 steps)
-// ---------------------------------------------------------------------------
-
-test("currentStep_profile_is_2_on_imported_path", () => {
-  assert.equal(computeCurrentStep("profile", true), 2);
-});
-
-test("currentStep_avatar_is_3_on_imported_path", () => {
-  assert.equal(computeCurrentStep("avatar", true), 3);
-});
-
-test("currentStep_theme_is_4_on_imported_path", () => {
-  assert.equal(computeCurrentStep("theme", true), 4);
-});
-
-test("currentStep_setup_is_5_on_imported_path", () => {
-  assert.equal(computeCurrentStep("setup", true), 5);
-});
-
-// ---------------------------------------------------------------------------
-// Routing: profile submit goes to backup (fresh) or avatar (imported)
-// ---------------------------------------------------------------------------
-
-test("profile_submit_routes_to_backup_on_fresh_path", () => {
-  const identityWasImported = false;
-  const nextPage = identityWasImported ? "avatar" : "backup";
-  assert.equal(nextPage, "backup");
-});
-
-test("profile_submit_routes_to_avatar_on_imported_path", () => {
-  const identityWasImported = true;
-  const nextPage = identityWasImported ? "avatar" : "backup";
-  assert.equal(nextPage, "avatar");
+test("currentStep_falls_back_to_1_for_pages_outside_the_step_list", () => {
+  assert.equal(computeCurrentStep("membership-denied"), 1);
 });
 
 // ---------------------------------------------------------------------------
diff --git a/desktop/src/features/onboarding/ui/types.ts b/desktop/src/features/onboarding/ui/types.ts
index 109058d6b..78eda6533 100644
--- a/desktop/src/features/onboarding/ui/types.ts
+++ b/desktop/src/features/onboarding/ui/types.ts
@@ -3,10 +3,7 @@ import type { AcpRuntimeCatalogEntry, Profile } from "@/shared/api/types";
 export type OnboardingPage =
   | "profile"
   | "key-import"
-  | "backup"
   | "avatar"
-  | "theme"
-  | "setup"
   | "membership-denied";
 
 export type OnboardingActions = {
@@ -64,11 +61,6 @@ export type SetupStepActions = {
   complete: () => void;
 };
 
-export type ThemeStepActions = {
-  skip: () => void;
-  submit: () => void;
-};
-
 export type SetupStepRuntimeState = {
   errorMessage: string | null;
   isChecking: boolean;
diff --git a/desktop/src/main.tsx b/desktop/src/main.tsx
index b0c63cbac..a73105a67 100644
--- a/desktop/src/main.tsx
+++ b/desktop/src/main.tsx
@@ -74,7 +74,7 @@ function renderApp() {
     <React.StrictMode>
       <CommunitiesProvider>
         <CommunityOnboardingProvider>
-          <ThemeProvider defaultTheme="houston">
+          <ThemeProvider defaultTheme="buzz">
             <TooltipProvider delayDuration={300}>
               <EmojiBurstProvider>
                 <PoofBurstProvider>
diff --git a/desktop/src/shared/theme/ThemeProvider.tsx b/desktop/src/shared/theme/ThemeProvider.tsx
index bb22f6327..6b41f4f05 100644
--- a/desktop/src/shared/theme/ThemeProvider.tsx
+++ b/desktop/src/shared/theme/ThemeProvider.tsx
@@ -452,7 +452,7 @@ async function applyTheme(name: SyntaxThemeName): Promise<{ isDark: boolean }> {
 
 export function ThemeProvider({
   children,
-  defaultTheme = "houston",
+  defaultTheme = "buzz",
 }: ThemeProviderProps) {
   // Apply cached vars synchronously before first render
   const [selectedTheme, setSelectedTheme] = useState<string>(() => {
@@ -468,7 +468,12 @@ export function ThemeProvider({
     return window.localStorage.getItem(ACCENT_STORAGE_KEY) ?? DEFAULT_ACCENT;
   });
   const [followSystem, setFollowSystemState] = useState<boolean>(() => {
-    return window.localStorage.getItem(FOLLOW_SYSTEM_KEY) === "true";
+    const stored = window.localStorage.getItem(FOLLOW_SYSTEM_KEY);
+    if (stored !== null) return stored === "true";
+    // Fresh profiles (no saved theme) default to System mode so the Buzz
+    // default tracks the OS light/dark scheme. Profiles that picked a theme
+    // before this toggle existed keep their fixed theme until they opt in.
+    return window.localStorage.getItem(THEME_STORAGE_KEY) === null;
   });
   const [systemIsDark, setSystemIsDark] = useState<boolean>(() => {
     return window.matchMedia("(prefers-color-scheme: dark)").matches;
diff --git a/desktop/src/shared/theme/theme-loader.ts b/desktop/src/shared/theme/theme-loader.ts
index bd1efbe91..f74f0d090 100644
--- a/desktop/src/shared/theme/theme-loader.ts
+++ b/desktop/src/shared/theme/theme-loader.ts
@@ -124,16 +124,6 @@ export const SYNTAX_THEMES = [
 
 export type SyntaxThemeName = (typeof SYNTAX_THEMES)[number];
 
-const ONBOARDING_THEME_FALLBACK: SyntaxThemeName = "github-light-default";
-const ONBOARDING_THEME_PREFERENCES = [
-  "neutral",
-  ONBOARDING_THEME_FALLBACK,
-] as const;
-
-export const ONBOARDING_DEFAULT_THEME_NAME = (ONBOARDING_THEME_PREFERENCES.find(
-  (name) => (SYNTAX_THEMES as readonly string[]).includes(name),
-) ?? ONBOARDING_THEME_FALLBACK) as SyntaxThemeName;
-
 // Known light themes — used by the theme picker to show sun/moon icons
 // for themes that haven't been loaded yet.
 export const LIGHT_THEMES: ReadonlySet<SyntaxThemeName> = new Set([
diff --git a/desktop/tests/e2e/onboarding.spec.ts b/desktop/tests/e2e/onboarding.spec.ts
index 49e16b969..9baee43de 100644
--- a/desktop/tests/e2e/onboarding.spec.ts
+++ b/desktop/tests/e2e/onboarding.spec.ts
@@ -1072,8 +1072,10 @@ test("first-run onboarding shows setup loading until Welcome bootstrap completes
       wash instanceof HTMLElement ? window.getComputedStyle(wash) : null;
     return {
       animateElementCount: element.querySelectorAll("animate").length,
-      // The document itself must not flash white before the gate mounts
-      // (inline <style> in index.html; black fallback when no cached theme).
+      // The document must match the OS scheme before the gate mounts (inline
+      // <style> + script in index.html; with no cached theme the first-launch
+      // default is Buzz following the OS scheme — white here because
+      // Playwright's default color scheme is light).
       documentBackgroundColor: window.getComputedStyle(document.documentElement)
         .backgroundColor,
       grainientAnimation: washStyles?.animationName,
@@ -1088,7 +1090,7 @@ test("first-run onboarding shows setup loading until Welcome bootstrap completes
   });
   expect(gateTreatment).toEqual({
     animateElementCount: 0,
-    documentBackgroundColor: "rgb(0, 0, 0)",
+    documentBackgroundColor: "rgb(255, 255, 255)",
     grainientAnimation: "buzz-grainient-orbit",
     grainientUsesRadialGradients: true,
     markSvgsUseCurrentColor: true,
diff --git a/desktop/tests/e2e/profile.spec.ts b/desktop/tests/e2e/profile.spec.ts
index 2f2944bfd..c478faaf8 100644
--- a/desktop/tests/e2e/profile.spec.ts
+++ b/desktop/tests/e2e/profile.spec.ts
@@ -296,6 +296,13 @@ test("shows profile save feedback as a toast", async ({ page }) => {
 });
 
 test("nests the avatar edit button in a clipped notch", async ({ page }) => {
+  // Under the Buzz default theme the settings nav overrides `--sidebar-active`
+  // (white pill on the gradient) while the avatar edit button deliberately
+  // keeps the root accent-driven token, so the shared-token comparison below
+  // only holds outside the Buzz theme.
+  await page.addInitScript(() => {
+    window.localStorage.setItem("buzz-theme", "github-light");
+  });
   await page.goto("/");
 
   await openSettings(page, "profile");
@@ -1350,15 +1357,18 @@ test("opens settings with the keyboard shortcut and updates theme", async ({
   ).toBeVisible();
   await page.getByTestId("settings-nav-appearance").click();
 
-  // Default theme is catppuccin-macchiato (dark)
+  // Default is Buzz in System mode; Playwright's default color scheme is
+  // light, so the app boots with the light Buzz theme.
   await expect
     .poll(() =>
-      page.evaluate(() => document.documentElement.classList.contains("dark")),
+      page.evaluate(() => document.documentElement.classList.contains("light")),
     )
     .toBe(true);
 
-  // Switch to Light mode tab to reveal light themes
-  await page.getByRole("button", { name: "Light" }).click();
+  // Switch to Light mode tab to reveal light themes. Target the testid — in
+  // the default System mode the "Light" paired-theme tile shares the same
+  // accessible name as the mode button.
+  await page.getByTestId("appearance-mode-light").click();
 
   // Switch to a light theme — verifies dark→light transition
   await page.getByTestId("theme-option-github-light").click();
@@ -1390,7 +1400,7 @@ test("opens settings with the keyboard shortcut and updates theme", async ({
     .toBe("github-light");
 
   // Switch to Dark mode tab to reveal dark themes
-  await page.getByRole("button", { name: "Dark" }).click();
+  await page.getByTestId("appearance-mode-dark").click();
 
   // Switch back to a dark theme — verifies light→dark transition
   await page.getByTestId("theme-option-dracula").click();
diff --git a/desktop/tests/e2e/sidebar.spec.ts b/desktop/tests/e2e/sidebar.spec.ts
index f5ec16c53..200d8d029 100644
--- a/desktop/tests/e2e/sidebar.spec.ts
+++ b/desktop/tests/e2e/sidebar.spec.ts
@@ -80,7 +80,15 @@ test("leaving a channel from the context menu never freezes the app", async ({
   await expectAppClickable(page);
 });
 
-test("fades the pinned sidebar chrome edges", async ({ page }) => {
+test("fades the pinned sidebar chrome edges outside the Buzz theme", async ({
+  page,
+}) => {
+  // The Buzz default theme repaints the pinned header/footer with the
+  // sidebar gradient and drops the edge-fade pseudo-elements, so the fade
+  // treatment under test only exists on non-Buzz themes.
+  await page.addInitScript(() => {
+    window.localStorage.setItem("buzz-theme", "github-light");
+  });
   await page.goto("/");
 
   const pinnedHeader = page.getByTestId("sidebar-pinned-header");
diff --git a/desktop/tests/e2e/video-attachment.spec.ts b/desktop/tests/e2e/video-attachment.spec.ts
index c4bc4c70b..36c5dbdd6 100644
--- a/desktop/tests/e2e/video-attachment.spec.ts
+++ b/desktop/tests/e2e/video-attachment.spec.ts
@@ -11,6 +11,10 @@ const CONSTRAINED_LANDSCAPE_VIDEO_SHA = "d".repeat(64);
 const CONSTRAINED_LANDSCAPE_VIDEO_URL = `http://localhost:3000/media/${CONSTRAINED_LANDSCAPE_VIDEO_SHA}.mp4`;
 const VIDEO_REVIEW_NEUTRAL_ACCENT = "neutral";
 const VIDEO_REVIEW_LIGHT_THEME = "catppuccin-latte";
+// The fresh-profile default is the Buzz theme, which pins the neutral accent
+// regardless of the stored accent color. Accent-driven review foreground
+// assertions must run on a non-Buzz theme for the seeded accent to apply.
+const VIDEO_REVIEW_ACCENT_THEME = "houston";
 const VIDEO_REVIEW_ACCENT = "#ec4899";
 const VIDEO_REVIEW_ACCENT_FOREGROUND_RGB = "rgb(240, 115, 177)";
 const VIDEO_REVIEW_INDIGO_ACCENT = "#6366f1";
@@ -211,7 +215,9 @@ async function openReviewWithPostedTimecode(
 test("video upload previews use poster frames and inline videos open review mode", async ({
   page,
 }) => {
-  await installVideoReviewHarness(page);
+  await installVideoReviewHarness(page, {
+    themeName: VIDEO_REVIEW_ACCENT_THEME,
+  });
 
   await page.goto("/");
   await page.getByTestId("channel-general").click();
@@ -871,6 +877,7 @@ test("neutral accent uses the forced-dark review foreground", async ({
 test("dark accent uses a contrast-safe review foreground", async ({ page }) => {
   await installVideoReviewHarness(page, {
     accentColor: VIDEO_REVIEW_INDIGO_ACCENT,
+    themeName: VIDEO_REVIEW_ACCENT_THEME,
   });
 
   const reviewDialog = await openReviewWithPostedTimecode(