app/(app)/create/hooks/usePreviewSurfaceColor.ts

@@ -1,23 +1,8 @@
 "use client";
 
 import { useEffect, useState } from "react";
-import {
-  dominantColorFromImageUrl,
-  isPreviewSurfaceColor,
-  randomPreviewSurfaceColor,
-} from "../../../../lib/create/previewSurfaceColor";
-
-function storedOrRandom(
-  storedFallback: string | undefined,
-  persistFallback: (_color: string) => void,
-): string {
-  if (storedFallback && isPreviewSurfaceColor(storedFallback)) {
-    return storedFallback;
-  }
-  const next = randomPreviewSurfaceColor();
-  persistFallback(next);
-  return next;
-}
+import { dominantColorFromImageUrl } from "../../../../lib/create/previewSurfaceColor";
+import { resolvePreviewSurfaceFallback } from "../utils/resolvePreviewSurfaceFallback";
 
 /**
  * Fill for the review preview card. An uploaded logo contributes its most
@@ -27,7 +12,7 @@ function storedOrRandom(
  *
  * @param imageUrl Uploaded logo URL, or `null` when the user skipped the photo.
  * @param storedFallback Draft `previewSurfaceColor`, if already picked.
- * @param persistFallback Writes the fallback onto the draft once.
+ * @param persistFallback Writes the fallback onto React state once.
  * @returns A CSS color, or `undefined` before the client picks one.
  *
  * @example
@@ -42,15 +27,23 @@ export function usePreviewSurfaceColor(
 
   useEffect(() => {
     if (!imageUrl) {
+      const next = resolvePreviewSurfaceFallback(storedFallback);
+      persistFallback(next);
       // eslint-disable-next-line react-hooks/set-state-in-effect -- random fill is client-only; first paint stays on the fallback class
-      setColor(storedOrRandom(storedFallback, persistFallback));
+      setColor(next);
       return;
     }
 
     let cancelled = false;
-    void dominantColorFromImageUrl(imageUrl).then((next) => {
+    void dominantColorFromImageUrl(imageUrl).then((extracted) => {
       if (cancelled) return;
-      setColor(next ?? storedOrRandom(storedFallback, persistFallback));
+      if (extracted) {
+        setColor(extracted);
+        return;
+      }
+      const next = resolvePreviewSurfaceFallback(storedFallback);
+      persistFallback(next);
+      setColor(next);
     });
 
     return () => {

app/(app)/create/screens/review/FinalReviewScreen.tsx

@@ -34,6 +34,10 @@ import {
   vectorMarkPath,
 } from "../../../../../lib/assetUtils";
 import { isPreviewSurfaceColor } from "../../../../../lib/create/previewSurfaceColor";
+import {
+  persistDraftPreviewSurfaceColor,
+  readDraftPreviewSurfaceColor,
+} from "../../utils/resolvePreviewSurfaceFallback";
 
 const FACET_FALLBACK_ORDER: readonly TemplateFacetGroupKey[] = [
   "coreValues",
@@ -247,12 +251,19 @@ export function FinalReviewScreen({
       : undefined;
   const persistFallback = useCallback(
     (color: string) => {
-      replaceState((prev) =>
-        prev.previewSurfaceColor &&
+      replaceState((prev) => {
+        persistDraftPreviewSurfaceColor(color, prev);
+        const keep =
+          (prev.previewSurfaceColor &&
           isPreviewSurfaceColor(prev.previewSurfaceColor)
+            ? prev.previewSurfaceColor
+            : undefined) ??
+          readDraftPreviewSurfaceColor() ??
+          color;
+        return prev.previewSurfaceColor === keep
           ? prev
-          : { ...prev, previewSurfaceColor: color },
-      );
+          : { ...prev, previewSurfaceColor: keep };
+      });
     },
     [replaceState],
   );

app/(app)/create/utils/resolvePreviewSurfaceFallback.ts

@@ -0,0 +1,64 @@
+import type { CreateFlowState } from "../types";
+import {
+  isPreviewSurfaceColor,
+  randomPreviewSurfaceColor,
+} from "../../../../lib/create/previewSurfaceColor";
+import {
+  readAnonymousCreateFlowState,
+  writeAnonymousCreateFlowState,
+} from "./anonymousDraftStorage";
+
+function validPreviewSurfaceColor(
+  value: string | undefined,
+): string | undefined {
+  return typeof value === "string" && isPreviewSurfaceColor(value)
+    ? value
+    : undefined;
+}
+
+/** Existing draft fill from React state or localStorage, if it is a stored hsl. */
+export function readDraftPreviewSurfaceColor(
+  storedFallback?: string,
+): string | undefined {
+  return (
+    validPreviewSurfaceColor(storedFallback) ??
+    validPreviewSurfaceColor(
+      readAnonymousCreateFlowState().previewSurfaceColor,
+    )
+  );
+}
+
+/**
+ * Keep a fallback fill on the anonymous draft immediately. The provider’s
+ * first mirrored write is skipped, so waiting on React state loses the color
+ * across reload. `state` is merged so a write before hydrate does not drop
+ * other draft fields already in memory.
+ */
+export function persistDraftPreviewSurfaceColor(
+  color: string,
+  state: CreateFlowState = {},
+): void {
+  const next = validPreviewSurfaceColor(color);
+  if (!next) return;
+  const current = readAnonymousCreateFlowState();
+  const stored = validPreviewSurfaceColor(current.previewSurfaceColor);
+  writeAnonymousCreateFlowState({
+    ...current,
+    ...state,
+    previewSurfaceColor: stored ?? next,
+  });
+}
+
+/**
+ * Reuse the draft fill when one exists; otherwise pick one and write it now.
+ * Reads localStorage itself so a child effect can run before context hydrates.
+ */
+export function resolvePreviewSurfaceFallback(
+  storedFallback?: string,
+): string {
+  const existing = readDraftPreviewSurfaceColor(storedFallback);
+  if (existing) return existing;
+  const color = randomPreviewSurfaceColor();
+  persistDraftPreviewSurfaceColor(color);
+  return color;
+}

tests/components/FinalReviewPreviewSurface.test.tsx

@@ -1,10 +1,11 @@
 import { useEffect, useLayoutEffect } from "react";
-import { describe, expect, it, vi } from "vitest";
+import { beforeEach, describe, expect, it, vi } from "vitest";
 import { waitFor } from "@testing-library/react";
 import { renderWithProviders as render, screen } from "../utils/test-utils";
 import "@testing-library/jest-dom/vitest";
 import { FinalReviewScreen } from "../../app/(app)/create/screens/review/FinalReviewScreen";
 import { useCreateFlow } from "../../app/(app)/create/context/CreateFlowContext";
+import { CREATE_FLOW_ANONYMOUS_KEY } from "../../app/(app)/create/utils/anonymousDraftStorage";
 import {
   dominantColorFromImageUrl,
   randomPreviewSurfaceColor,
@@ -60,6 +61,10 @@ function FinalReviewWithStateProbe({
 }
 
 describe("Final review preview surface", () => {
+  beforeEach(() => {
+    window.localStorage.removeItem(CREATE_FLOW_ANONYMOUS_KEY);
+    vi.mocked(randomPreviewSurfaceColor).mockClear();
+  });
   it("fills the card from the uploaded logo’s most common color", async () => {
     render(<FinalReviewWithAvatar />);
 
@@ -95,6 +100,34 @@ describe("Final review preview surface", () => {
     expect(vi.mocked(randomPreviewSurfaceColor)).toHaveBeenCalled();
   });
 
+  it("reuses a fallback saved only in localStorage across a fresh mount", async () => {
+    window.localStorage.setItem(
+      CREATE_FLOW_ANONYMOUS_KEY,
+      JSON.stringify({
+        title: "Oak Park Commons",
+        communityContext: "Local mutual aid.",
+        previewSurfaceColor: "hsl(200, 60%, 80%)",
+      }),
+    );
+    let latest: CreateFlowState = {};
+    render(
+      <FinalReviewWithStateProbe
+        initial={{
+          title: "Oak Park Commons",
+          communityContext: "Local mutual aid.",
+        }}
+        onState={(state) => {
+          latest = state;
+        }}
+      />,
+    );
+
+    await waitFor(() => {
+      expect(latest.previewSurfaceColor).toBe("hsl(200, 60%, 80%)");
+    });
+    expect(vi.mocked(randomPreviewSurfaceColor)).not.toHaveBeenCalled();
+  });
+
   it("reuses the stored fallback instead of picking a new color", async () => {
     vi.mocked(randomPreviewSurfaceColor).mockClear();
     render(

tests/unit/resolvePreviewSurfaceFallback.test.ts

@@ -0,0 +1,71 @@
+import { beforeEach, describe, expect, it, vi } from "vitest";
+import { CREATE_FLOW_ANONYMOUS_KEY } from "../../app/(app)/create/utils/anonymousDraftStorage";
+import {
+  persistDraftPreviewSurfaceColor,
+  readDraftPreviewSurfaceColor,
+  resolvePreviewSurfaceFallback,
+} from "../../app/(app)/create/utils/resolvePreviewSurfaceFallback";
+import { randomPreviewSurfaceColor } from "../../lib/create/previewSurfaceColor";
+
+vi.mock("../../lib/create/previewSurfaceColor", async (importOriginal) => {
+  const actual =
+    await importOriginal<
+      typeof import("../../lib/create/previewSurfaceColor")
+    >();
+  return {
+    ...actual,
+    randomPreviewSurfaceColor: vi.fn(() => "hsl(12, 50%, 80%)"),
+  };
+});
+
+describe("resolvePreviewSurfaceFallback", () => {
+  beforeEach(() => {
+    window.localStorage.removeItem(CREATE_FLOW_ANONYMOUS_KEY);
+    vi.mocked(randomPreviewSurfaceColor).mockClear();
+  });
+
+  it("reuses a valid fill already on React state", () => {
+    expect(resolvePreviewSurfaceFallback("hsl(200, 60%, 80%)")).toBe(
+      "hsl(200, 60%, 80%)",
+    );
+    expect(randomPreviewSurfaceColor).not.toHaveBeenCalled();
+  });
+
+  it("reuses a fill already on the anonymous draft", () => {
+    window.localStorage.setItem(
+      CREATE_FLOW_ANONYMOUS_KEY,
+      JSON.stringify({
+        title: "Oak Park Commons",
+        previewSurfaceColor: "hsl(200, 60%, 80%)",
+      }),
+    );
+    expect(resolvePreviewSurfaceFallback(undefined)).toBe(
+      "hsl(200, 60%, 80%)",
+    );
+    expect(randomPreviewSurfaceColor).not.toHaveBeenCalled();
+  });
+
+  it("picks once and writes it onto the anonymous draft", () => {
+    expect(resolvePreviewSurfaceFallback(undefined)).toBe(
+      "hsl(12, 50%, 80%)",
+    );
+    expect(randomPreviewSurfaceColor).toHaveBeenCalledTimes(1);
+    expect(readDraftPreviewSurfaceColor()).toBe("hsl(12, 50%, 80%)");
+    expect(resolvePreviewSurfaceFallback(undefined)).toBe(
+      "hsl(12, 50%, 80%)",
+    );
+    expect(randomPreviewSurfaceColor).toHaveBeenCalledTimes(1);
+  });
+
+  it("does not replace a fill already stored on the draft", () => {
+    window.localStorage.setItem(
+      CREATE_FLOW_ANONYMOUS_KEY,
+      JSON.stringify({
+        title: "Oak Park Commons",
+        previewSurfaceColor: "hsl(200, 60%, 80%)",
+      }),
+    );
+    persistDraftPreviewSurfaceColor("hsl(12, 50%, 80%)");
+    expect(readDraftPreviewSurfaceColor()).toBe("hsl(200, 60%, 80%)");
+  });
+});