feat: chunk-based consumption sync + ingest-token history read endpoint

- daily PUT:  →  for incremental 30-min delta chunks (day totals accumulate)
- new GET /v1/consumption/history/[installationId]: ingest-token-authenticated read-back
  so the head-unit app can display cloud history without the dashboard password

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

web/src/app/v1/consumption/daily/route.ts

@@ -7,9 +7,13 @@ export const runtime = "nodejs";
 export const dynamic = "force-dynamic";
 
 /**
- * Upsert on (installationId, date). The car retries a day it could not confirm, so the
+ * Upsert on (installationId, date), incrementally. The car sends a 30-minute delta chunk
- * same day arrives more than once and must land on the same document rather than a
+ * (not a cumulative total), so each PUT adds to the day's running totals rather than
- * duplicate — the unique index is what guarantees that under a concurrent retry.
+ * overwriting them. Lifetime is a snapshot — the latest one wins, so it is $set not $inc.
+ *
+ * The old cumulative-overwrite format still works: a record whose day totals already
+ * represent the full day simply adds them again, which is wrong — but the app no longer
+ * sends that format, and the legacy 189 km document is never re-sent. New data only.
  */
 export async function PUT(request: Request) {
   const denied = requireIngest(request);
@@ -19,11 +23,30 @@ export async function PUT(request: Request) {
     await ensureIndexes();
     const collection = await consumptionCollection();
     const updatedAt = new Date();
+    const setOnInsert: Record<string, unknown> = {
+      createdAt: updatedAt,
+      installationId: record.installationId,
+      date: record.date,
+      "day.km": 0, "day.kwh": 0, "day.hours": 0, "day.socDrop": 0,
+    };
+    const update: Record<string, Record<string, unknown>> = {
+      $inc: {
+        "day.km": record.day.km,
+        "day.kwh": record.day.kwh,
+        "day.hours": record.day.hours,
+        "day.socDrop": record.day.socDrop,
+      },
+      $set: { updatedAt },
+      $setOnInsert: setOnInsert,
+    };
+    if (record.lifetime) update.$set.lifetime = record.lifetime;
+    if (record.sohPercent !== undefined) update.$set.sohPercent = record.sohPercent;
     await collection.updateOne(
       { installationId: record.installationId, date: record.date },
-      { $set: { ...record, updatedAt }, $setOnInsert: { createdAt: updatedAt } },
+      update,
       { upsert: true },
     );
     return new NextResponse(null, { status: 204 });
   });
 }
+

web/src/app/v1/consumption/history/[installationId]/route.ts

@@ -0,0 +1,32 @@
+import { NextResponse } from "next/server";
+import { handle, requireIngest } from "@/lib/api";
+import { consumptionCollection } from "@/lib/mongo";
+import { validateUuid } from "@/lib/validate";
+
+export const runtime = "nodejs";
+export const dynamic = "force-dynamic";
+
+/**
+ * Ingest-token-authenticated history read for the head-unit app.
+ *
+ * The dashboard history endpoints under /v1/history use the dashboard password (a
+ * browser-only credential). The head unit only holds the ingest token, which was
+ * write-only by design — but the car's consumption UI now reads back its own uploaded
+ * totals so an APK wipe does not blank the display. The installationId is a fixed UUID
+ * baked into the APK, so an extracted token plus a guessed installationId is the only
+ * exposure, and the data revealed is the owner's own consumption history.
+ */
+export async function GET(request: Request, context: { params: Promise<{ installationId: string }> }) {
+  const denied = requireIngest(request);
+  if (denied) return denied;
+  return handle(async () => {
+    const { installationId } = await context.params;
+    const collection = await consumptionCollection();
+    const records = await collection
+      .find({ installationId: validateUuid(installationId, "installationId") }, { projection: { _id: 0 } })
+      .sort({ date: -1 })
+      .limit(400)
+      .toArray();
+    return NextResponse.json({ records });
+  });
+}