intake: POST /api/intake router + PUT /api/transactions/[id]/line-items (plan §11 C1, C2)

One upload point, every applicable step. Persist the batch, classify each
file, ONE LiteLLM call (cloud-budget, temperature 0, strict json_schema; PDFs
as unpdf text, never pixels) with an order-item prompt that keeps names
verbatim, header (merchant, date, total), merchant pattern
(coles|woolworths|woolies|aldi|iga|foodworks|costco) -> grocery | food | ask,
exact (platform, merchant, date, total) match against transactions +
expense_metadata, then act:

- food + unique match  -> replace line_items via the C2 path, 'enriched'
- food + miss/ambiguity -> 'candidates' (same merchant ±3d) with
  intake_use_candidate / intake_create buttons; never auto-creates
- grocery              -> original files to pantry POST /api/capture with
  finance_target_transaction_id + finance_action enrich|create (C3);
  409 -> 'duplicate'
- ask / needs_header / held / duplicate / unsupported as replies, not writes

Reconciliation is against the printed item subtotal (a delivery total is
items + fees - promotions: 18.94 of Coles lines settled at 5.74),  or
2%, else 'held'. Originals are kept under INTAKE_FILE_DIR by sha256 so a later
'Groceries' tap can still forward them.

C2 is an idempotent replace on transaction_id = :id OR
matched_transaction_id = :id, accepts INTAKE_TOKEN or RECEIPT_INGEST_TOKEN,
creates the expense_metadata row when absent, 404 when the transaction does
not exist, returns {previous_line_items, line_items} so pantry's undo is the
same call with the previous list.

src/lib/intake-pantry.ts

@@ -0,0 +1,76 @@
+import type { StoredFile } from "@/lib/intake-files";
+
+/**
+ * finance → pantry hand-off for a grocery upload (plan §11 C3).
+ *
+ * The ORIGINAL files go across, not the extracted items: pantry owns grocery
+ * extraction (canonical names, categories, staples) and its capture board is
+ * the review surface. What finance adds is the routing decision — which
+ * transaction the confirm should enrich, or that it should create one — carried
+ * in the `intake` field so pantry's confirm seam (C4) can suppress the ING-10
+ * create that would otherwise double-book an order the email already booked.
+ */
+
+export type PantryForwardArgs = {
+  files: StoredFile[];
+  batchId: string;
+  platform: string | null;
+  sharedBy: string | null;
+  financeTargetTransactionId: number | null;
+  financeAction: "enrich" | "create";
+};
+
+export type PantryForwardResult = { captureId: number; itemCount: number | null };
+
+export class PantryDuplicateError extends Error {
+  constructor(
+    public readonly captureId: number | null,
+    public readonly reason: string
+  ) {
+    super(reason);
+  }
+}
+
+export class PantryUnavailableError extends Error {}
+
+export type PantryForward = (args: PantryForwardArgs) => Promise<PantryForwardResult>;
+
+export function pantryForwarder(opts: { baseUrl?: string; token?: string; fetchImpl?: typeof fetch } = {}): PantryForward {
+  return async (args) => {
+    const baseUrl = (opts.baseUrl ?? process.env.PANTRY_BASE_URL ?? "").replace(/\/$/, "");
+    const token = opts.token ?? process.env.RECEIPT_INGEST_TOKEN;
+    if (!baseUrl || !token) throw new PantryUnavailableError("PANTRY_BASE_URL / RECEIPT_INGEST_TOKEN are not configured");
+    const doFetch = opts.fetchImpl ?? fetch;
+
+    const form = new FormData();
+    for (const f of args.files) {
+      form.append("image", new Blob([new Uint8Array(f.bytes)], { type: f.type }), f.name);
+    }
+    form.append("source", "receipt");
+    form.append(
+      "intake",
+      JSON.stringify({
+        batch_id: args.batchId,
+        platform: args.platform,
+        origin: "intake",
+        shared_by: args.sharedBy,
+        finance_target_transaction_id: args.financeTargetTransactionId,
+        finance_action: args.financeAction,
+      })
+    );
+
+    let response: Response;
+    try {
+      response = await doFetch(`${baseUrl}/api/capture`, { method: "POST", headers: { "x-ingest-token": token }, body: form });
+    } catch (e) {
+      throw new PantryUnavailableError(`pantry unreachable: ${e instanceof Error ? e.message : String(e)}`);
+    }
+    const body = (await response.json().catch(() => ({}))) as { captureId?: number; error?: string; items?: unknown[]; reason?: string };
+    if (response.status === 409) {
+      throw new PantryDuplicateError(typeof body.captureId === "number" ? body.captureId : null, body.reason ?? body.error ?? "already captured");
+    }
+    if (!response.ok) throw new PantryUnavailableError(`pantry returned ${response.status}: ${body.error ?? ""}`.trim());
+    if (typeof body.captureId !== "number") throw new PantryUnavailableError("pantry returned no captureId");
+    return { captureId: body.captureId, itemCount: Array.isArray(body.items) ? body.items.length : null };
+  };
+}