fix: unify day boundaries on device-local time, JSON import preview parity

- Limits/streaks/greeting now use device-local days (was hardcoded Europe/London),
  matching dashboard metrics; label copy updated
- JSON imports now go through the same preview/duplicate-detection modal as Excel

src/App.tsx

@@ -21,7 +21,6 @@ import {
   createEntries,
   createEntry,
   deleteEntry as deleteEntryDocument,
-  isDuplicateDraft,
   listEntries,
   updateEntry,
 } from "./lib/appwriteEntries";
@@ -52,7 +51,7 @@ import {
 } from "./lib/userLimits";
 import { createExcelExport, downloadBlob, parseExcelImport } from "./lib/excel";
 import { buildEntryDerived, groupByDay, groupByFlavour, groupByWeek, humanDateTime, makeId } from "./lib/metrics";
-import { exportPayload, parseImport } from "./lib/storage";
+import { buildJsonImportPreview, exportPayload, parseImport } from "./lib/storage";
 import { useToasts } from "./lib/toasts";
 import type {
   AppView,
@@ -547,18 +546,18 @@ function App() {
     }
   }
 
-  async function confirmExcelImport() {
+  async function confirmImportPreview() {
     if (!user || !importPreview) return;
     const drafts = importPreview.rows
       .filter((row) => row.entry && !row.errors.length && !row.duplicate)
       .map((row) => row.entry as EntryDraft);
 
     if (!drafts.length) {
-      setNotice("No valid new Excel rows to import.");
+      setNotice("No valid new rows to import.");
       return;
     }
 
-    setBusyAction("confirm-excel-import");
+    setBusyAction("confirm-import");
     setSyncError("");
     importInFlightRef.current = true;
     setImportProgress({ done: 0, total: drafts.length });
@@ -566,7 +565,7 @@ function App() {
       const saved = await createEntries(user.$id, drafts, (done, total) => setImportProgress({ done, total }));
       setEntries((current) => sortEntries([...saved, ...current]));
       setImportPreview(null);
-      setNotice(`${saved.length} Excel row${saved.length === 1 ? "" : "s"} saved to Appwrite.`);
+      setNotice(`${saved.length} row${saved.length === 1 ? "" : "s"} saved to Appwrite.`);
     } catch (error) {
       setSyncError(appwriteErrorMessage(error));
     } finally {
@@ -588,18 +587,12 @@ function App() {
     setSyncError("");
     try {
       const drafts = parseImport(await file.text());
-      const uniqueDrafts = drafts.filter((draft) => !isDuplicateDraft(entries, draft));
-      if (!uniqueDrafts.length) {
-        setNotice("No new JSON entries found.");
-        return;
-      }
-      importInFlightRef.current = true;
-      const saved = await createEntries(user.$id, uniqueDrafts.map((draft) => ({ ...draft, source: "json" })));
-      setEntries((current) => sortEntries([...saved, ...current]));      setNotice(`${saved.length} JSON entr${saved.length === 1 ? "y" : "ies"} saved to Appwrite.`);
+      const preview = buildJsonImportPreview(drafts, entries, file.name);
+      setImportPreview(preview);
+      setNotice(`${preview.rows.length} JSON row${preview.rows.length === 1 ? "" : "s"} parsed for review.`);
     } catch (error) {
       setSyncError(error instanceof Error ? error.message : "JSON import failed.");
     } finally {
-      importInFlightRef.current = false;
       if (jsonFileInputRef.current) jsonFileInputRef.current.value = "";
       setBusyAction(null);
     }
@@ -810,11 +803,11 @@ function App() {
       />
 
       <ImportPreviewModal
-        busy={busyAction === "confirm-excel-import"}
+        busy={busyAction === "confirm-import"}
         preview={importPreview}
         importProgress={importProgress}
         onClose={() => setImportPreview(null)}
-        onConfirm={() => void confirmExcelImport()}
+        onConfirm={() => void confirmImportPreview()}
       />
 
       <ConfirmDialog

src/components/ImportPreviewModal.tsx

@@ -37,7 +37,9 @@ export function ImportPreviewModal({
         >
           <div className="mb-5 flex items-start justify-between gap-4">
             <div>
-              <p className="text-sm font-medium uppercase tracking-[0.18em] text-pink-100">Excel import</p>
+              <p className="text-sm font-medium uppercase tracking-[0.18em] text-pink-100">
+                {preview.fileName.toLowerCase().endsWith(".json") ? "JSON import" : "Excel import"}
+              </p>
               <h2 id="import-preview-title" className="mt-1 text-3xl font-semibold tracking-tight text-white">
                 Preview rows
               </h2>

src/components/LimitsSettingsForm.tsx

@@ -142,7 +142,7 @@ export function LimitsSettingsForm({ limits, check, saving, onSave }: LimitsSett
             value={canInput}
             onChange={(event) => handleCanInputChange(event.target.value)}
           />
-          <span className="text-xs text-slate-500">Leave empty to remove. Counts use BST calendar days.</span>
+          <span className="text-xs text-slate-500">Leave empty to remove. Counts use device-local calendar days.</span>
         </label>
 
         <label className="grid gap-2 text-sm">
@@ -170,7 +170,7 @@ export function LimitsSettingsForm({ limits, check, saving, onSave }: LimitsSett
           value={stopInput}
           onChange={(event) => setStopInput(event.target.value)}
         />
-        <span className="text-xs text-slate-500">Europe/London (BST/GMT). Leave empty to remove.</span>
+        <span className="text-xs text-slate-500">Your device's local time. Leave empty to remove.</span>
       </label>
 
       {previewParts.length ? (

src/components/views/SettingsView.tsx

@@ -61,7 +61,7 @@ export function SettingsView({
   return (
     <div className="grid gap-4 xl:grid-cols-[1fr_0.8fr]">
       <div className="grid content-start gap-4">
-        <AppCard title="Limits" subtitle="Personal caps for cans, spend, and stop time (BST)">
+        <AppCard title="Limits" subtitle="Personal caps for cans, spend, and stop time (local time)">
           <LimitsSettingsForm
             limits={userLimits}
             check={limitCheck}

src/lib/greeting.ts

@@ -20,12 +20,7 @@ type GreetingResult = {
 };
 
 export function getBstHour(date = new Date()) {
-  const hour = new Intl.DateTimeFormat("en-GB", {
-    timeZone: "Europe/London",
-    hour: "numeric",
-    hour12: false,
-  }).format(date);
-  return Number.parseInt(hour, 10);
+  return date.getHours();
 }
 
 export function buildDynamicGreeting(input: GreetingInput): GreetingResult {

src/lib/storage.ts

@@ -1,5 +1,6 @@
 import { flavourMeta } from "../data/flavours";
-import type { EntryDraft, RedBullEntry } from "../types";
+import { makeImportKey } from "./metrics";
+import type { EntryDraft, ImportPreview, ImportPreviewRow, RedBullEntry } from "../types";
 
 export function exportPayload(entries: RedBullEntry[]) {
   return JSON.stringify(
@@ -28,6 +29,32 @@ export function parseImport(raw: string): EntryDraft[] {
   return valid;
 }
 
+export function buildJsonImportPreview(
+  drafts: EntryDraft[],
+  existingEntries: RedBullEntry[],
+  fileName: string,
+): ImportPreview {
+  const seen = new Set(existingEntries.map((entry) => entry.importKey || makeImportKey(entry)));
+  const rows: ImportPreviewRow[] = drafts.map((draft, index) => {
+    const key = makeImportKey({
+      ...draft,
+      dateTime: new Date(draft.dateTime).toISOString(),
+      notes: draft.notes ?? "",
+      store: draft.store ?? "",
+    });
+    const duplicate = seen.has(key);
+    if (!duplicate) seen.add(key);
+    return {
+      rowNumber: index + 1,
+      entry: draft,
+      errors: [],
+      duplicate,
+      duplicateReason: duplicate ? "Matches an existing or earlier imported row." : undefined,
+    };
+  });
+  return { fileName, rows };
+}
+
 function coerceEntryDraft(value: unknown): EntryDraft | null {
   if (!value || typeof value !== "object") return null;
   const entry = value as Partial<RedBullEntry>;

src/lib/userLimits.ts

@@ -1,6 +1,6 @@
 import type { EntryDraft, LimitCheckResult, LimitViolation, RedBullEntry, UserLimits } from "../types";
 import { getBstHour } from "./greeting";
-import { currency, spendFor, sum } from "./metrics";
+import { currency, formatDateKey, spendFor, sum } from "./metrics";
 
 export const DEFAULT_LIMITS: UserLimits = {};
 
@@ -59,25 +59,11 @@ export function mergePrefsWithLimits(
 }
 
 export function formatBstDateKey(date = new Date()) {
-  return new Intl.DateTimeFormat("en-CA", {
-    timeZone: "Europe/London",
-    year: "numeric",
-    month: "2-digit",
-    day: "2-digit",
-  }).format(date);
+  return formatDateKey(date);
 }
 
 export function getBstMinutes(date = new Date()) {
-  const parts = new Intl.DateTimeFormat("en-GB", {
-    timeZone: "Europe/London",
-    hour: "numeric",
-    minute: "numeric",
-    hour12: false,
-  }).formatToParts(date);
-
-  const hour = Number(parts.find((part) => part.type === "hour")?.value ?? 0);
-  const minute = Number(parts.find((part) => part.type === "minute")?.value ?? 0);
-  return hour * 60 + minute;
+  return date.getHours() * 60 + date.getMinutes();
 }
 
 export function parseStopTimeMinutes(stopTime: string) {
@@ -101,7 +87,7 @@ export function formatStopTimeLabel(stopTime: string) {
   }).format(date);
 }
 
-function entriesTodayBst(entries: RedBullEntry[], ref = new Date()) {
+function entriesToday(entries: RedBullEntry[], ref = new Date()) {
   const key = formatBstDateKey(ref);
   return entries.filter((entry) => formatBstDateKey(new Date(entry.dateTime)) === key);
 }
@@ -111,7 +97,7 @@ function spendForDraft(draft: EntryDraft) {
 }
 
 function todayTotals(entries: RedBullEntry[], excludeEntryId?: string, ref = new Date()) {
-  const todayEntries = entriesTodayBst(entries, ref).filter((entry) => entry.id !== excludeEntryId);
+  const todayEntries = entriesToday(entries, ref).filter((entry) => entry.id !== excludeEntryId);
   return {
     todayCans: sum(todayEntries, (entry) => entry.cans),
     todaySpend: sum(todayEntries, spendFor),
@@ -171,7 +157,7 @@ export function limitStatusMessage(
 
   if (violations.includes("cans") && limits.dailyCanLimit != null) {
     lines.push(
-      `This would bring you to ${check.projectedCans.toFixed(1)}/${limits.dailyCanLimit} cans today (BST).`,
+      `This would bring you to ${check.projectedCans.toFixed(1)}/${limits.dailyCanLimit} cans today.`,
     );
   }
 
@@ -182,7 +168,7 @@ export function limitStatusMessage(
   }
 
   if (violations.includes("stopTime") && limits.stopTime) {
-    lines.push(`You're past your stop time (${formatStopTimeLabel(limits.stopTime)} BST).`);
+    lines.push(`You're past your stop time (${formatStopTimeLabel(limits.stopTime)}).`);
   }
 
   return lines.join(" ");