Merge commit '9576d1f01f' into dev

surfsense_backend/app/routes/stripe_routes.py

@@ -26,6 +26,7 @@ from app.schemas.stripe import (
     CreateCheckoutSessionResponse,
     CreateTokenCheckoutSessionRequest,
     CreateTokenCheckoutSessionResponse,
+    FinalizeCheckoutResponse,
     PagePurchaseHistoryResponse,
     StripeStatusResponse,
     StripeWebhookResponse,
@@ -65,7 +66,15 @@ def _get_checkout_urls(search_space_id: int) -> tuple[str, str]:
         )
 
     base_url = config.NEXT_FRONTEND_URL.rstrip("/")
-    success_url = f"{base_url}/dashboard/{search_space_id}/purchase-success"
+    # Stripe substitutes ``{CHECKOUT_SESSION_ID}`` with the actual session id
+    # at redirect time. The frontend uses it to call /stripe/finalize-checkout
+    # which fulfils synchronously without waiting for the webhook — fixing the
+    # webhook-vs-redirect race where users land on /purchase-success before
+    # checkout.session.completed has been delivered.
+    success_url = (
+        f"{base_url}/dashboard/{search_space_id}/purchase-success"
+        f"?session_id={{CHECKOUT_SESSION_ID}}"
+    )
     cancel_url = f"{base_url}/dashboard/{search_space_id}/purchase-cancel"
     return success_url, cancel_url
 
@@ -88,10 +97,62 @@ def _normalize_optional_string(value: Any) -> str | None:
 
 
 def _get_metadata(checkout_session: Any) -> dict[str, str]:
-    metadata = getattr(checkout_session, "metadata", None) or {}
+    """Extract checkout session metadata as a plain ``str -> str`` dict.
+
+    In ``stripe>=15.0`` ``StripeObject`` is no longer a ``dict`` subclass
+    and exposes neither ``items()`` nor ``__iter__`` nor ``keys()``.
+    ``dict(obj)`` falls into the sequence protocol and raises
+    ``KeyError: 0``; ``obj.items()`` raises ``AttributeError``. The
+    supported way to materialize a ``StripeObject`` as a plain dict is
+    its ``to_dict()`` method (added in stripe-python 8.x, present in 15.x).
+    """
+    metadata = getattr(checkout_session, "metadata", None)
+    if metadata is None:
+        return {}
+
+    # 1. Plain dict (older SDKs that subclassed dict, JSON-decoded events
+    #    in tests, etc.).
     if isinstance(metadata, dict):
-        return {str(key): str(value) for key, value in metadata.items()}
+        return {str(k): str(v) for k, v in metadata.items()}
-    return dict(metadata)
+
+    # 2. Modern Stripe SDK: every ``StripeObject`` has ``to_dict()``.
+    #    ``recursive=False`` is correct because Stripe metadata values
+    #    are always primitive strings.
+    to_dict = getattr(metadata, "to_dict", None)
+    if callable(to_dict):
+        try:
+            d = to_dict(recursive=False)
+            if isinstance(d, dict):
+                return {str(k): str(v) for k, v in d.items()}
+        except Exception:
+            logger.exception(
+                "Stripe metadata.to_dict() failed for session %s",
+                getattr(checkout_session, "id", "?"),
+            )
+
+    # 3. Last-resort: read the SDK's private ``_data`` backing dict.
+    #    Stable across stripe-python 6.x -> 15.x.
+    inner = getattr(metadata, "_data", None)
+    if isinstance(inner, dict):
+        return {str(k): str(v) for k, v in inner.items()}
+
+    logger.warning(
+        "Could not extract metadata from checkout session %s (metadata type=%s)",
+        getattr(checkout_session, "id", "?"),
+        type(metadata).__name__,
+    )
+    return {}
+
+
+# Canonical purchase_type metadata values. ``premium_credit`` was emitted
+# by an earlier release of ``create_token_checkout_session`` so it's still
+# accepted on the read side for backward compat with in-flight sessions.
+_PURCHASE_TYPE_TOKEN_VALUES = frozenset({"premium_tokens", "premium_credit"})
+
+
+def _is_token_purchase(metadata: dict[str, str]) -> bool:
+    """Return True for premium-credit (a.k.a. premium_token) purchases."""
+    return metadata.get("purchase_type", "page_packs") in _PURCHASE_TYPE_TOKEN_VALUES
 
 
 async def _get_or_create_purchase_from_checkout_session(
@@ -439,45 +500,217 @@ async def stripe_webhook(
             detail="Invalid Stripe webhook signature.",
         ) from exc
 
-    if event.type in {
+    try:
-        "checkout.session.completed",
+        if event.type in {
-        "checkout.session.async_payment_succeeded",
+            "checkout.session.completed",
-    }:
+            "checkout.session.async_payment_succeeded",
-        checkout_session = event.data.object
-        payment_status = getattr(checkout_session, "payment_status", None)
-
-        if event.type == "checkout.session.completed" and payment_status not in {
-            "paid",
-            "no_payment_required",
         }:
-            logger.info(
+            checkout_session = event.data.object
-                "Received checkout.session.completed for unpaid session %s; waiting for async success.",
+            payment_status = getattr(checkout_session, "payment_status", None)
-                checkout_session.id,
-            )
-            return StripeWebhookResponse()
 
-        metadata = _get_metadata(checkout_session)
+            if event.type == "checkout.session.completed" and payment_status not in {
-        purchase_type = metadata.get("purchase_type", "page_packs")
+                "paid",
-        if purchase_type == "premium_tokens":
+                "no_payment_required",
-            return await _fulfill_completed_token_purchase(db_session, checkout_session)
+            }:
-        return await _fulfill_completed_purchase(db_session, checkout_session)
+                logger.info(
+                    "Received checkout.session.completed for unpaid session %s; waiting for async success.",
+                    checkout_session.id,
+                )
+                return StripeWebhookResponse()
 
-    if event.type in {
+            metadata = _get_metadata(checkout_session)
-        "checkout.session.async_payment_failed",
+            if _is_token_purchase(metadata):
-        "checkout.session.expired",
+                return await _fulfill_completed_token_purchase(
-    }:
+                    db_session, checkout_session
-        checkout_session = event.data.object
+                )
-        metadata = _get_metadata(checkout_session)
+            return await _fulfill_completed_purchase(db_session, checkout_session)
-        purchase_type = metadata.get("purchase_type", "page_packs")
+
-        if purchase_type == "premium_tokens":
+        if event.type in {
-            return await _mark_token_purchase_failed(
+            "checkout.session.async_payment_failed",
-                db_session, str(checkout_session.id)
+            "checkout.session.expired",
-            )
+        }:
-        return await _mark_purchase_failed(db_session, str(checkout_session.id))
+            checkout_session = event.data.object
+            metadata = _get_metadata(checkout_session)
+            if _is_token_purchase(metadata):
+                return await _mark_token_purchase_failed(
+                    db_session, str(checkout_session.id)
+                )
+            return await _mark_purchase_failed(db_session, str(checkout_session.id))
+    except Exception:
+        # Re-raise so FastAPI returns 500 and Stripe retries this delivery.
+        # Logging here gives us a structured trail with event id + type so
+        # future webhook bugs surface immediately in the logs without
+        # having to grep by request_id.
+        logger.exception(
+            "Stripe webhook handler failed for event id=%s type=%s — Stripe will retry",
+            getattr(event, "id", "?"),
+            getattr(event, "type", "?"),
+        )
+        raise
 
     return StripeWebhookResponse()
 
 
+@router.get("/finalize-checkout", response_model=FinalizeCheckoutResponse)
+async def finalize_checkout(
+    session_id: str,
+    user: User = Depends(current_active_user),
+    db_session: AsyncSession = Depends(get_async_session),
+) -> FinalizeCheckoutResponse:
+    """Synchronously fulfil a checkout session from the success page.
+
+    Solves the webhook-vs-redirect race: the user lands on
+    ``/dashboard/<id>/purchase-success?session_id=cs_...`` typically a
+    few hundred ms after paying, but Stripe's
+    ``checkout.session.completed`` webhook can take 5-30s+ to arrive.
+    Calling this endpoint on success-page mount fulfils the purchase
+    immediately by retrieving the session from Stripe's API and
+    invoking the same idempotent helpers the webhook uses.
+
+    Idempotency: if the webhook has already fulfilled this purchase
+    (status=COMPLETED), the helpers short-circuit and we just return
+    the latest balance. Concurrent webhook + finalize calls are safe
+    because both acquire ``SELECT ... FOR UPDATE`` on the purchase row.
+
+    Authorization: the session's ``client_reference_id`` must match the
+    authenticated user's id. This prevents a user from finalising
+    someone else's checkout session if they happen to know the id.
+    """
+    stripe_client = get_stripe_client()
+
+    try:
+        checkout_session = stripe_client.v1.checkout.sessions.retrieve(session_id)
+    except StripeError as exc:
+        logger.warning(
+            "finalize_checkout: stripe lookup failed for session=%s user=%s: %s",
+            session_id,
+            user.id,
+            exc,
+        )
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail="Checkout session not found.",
+        ) from exc
+
+    # Authorization check: the user finalising must be the user who
+    # initiated the checkout. ``client_reference_id`` is set in
+    # ``create_checkout_session`` / ``create_token_checkout_session``.
+    client_reference_id = getattr(checkout_session, "client_reference_id", None)
+    if client_reference_id != str(user.id):
+        logger.warning(
+            "finalize_checkout: ownership mismatch session=%s client_ref=%s user=%s",
+            session_id,
+            client_reference_id,
+            user.id,
+        )
+        raise HTTPException(
+            status_code=status.HTTP_403_FORBIDDEN,
+            detail="This checkout session does not belong to you.",
+        )
+
+    metadata = _get_metadata(checkout_session)
+    is_token = _is_token_purchase(metadata)
+    payment_status = getattr(checkout_session, "payment_status", None)
+    session_status = getattr(checkout_session, "status", None)
+
+    # Defensive fallback: if metadata can't be read for any reason
+    # (extraction failure, manually-created session in Stripe dashboard,
+    # SDK upgrade breaking ``to_dict``, etc.) we'd otherwise route every
+    # purchase to the page_packs handler and get stuck. Resolve the
+    # purchase_type by checking which table actually has the row keyed
+    # by this Stripe session id.
+    if not metadata:
+        existing_token_purchase = (
+            await db_session.execute(
+                select(PremiumTokenPurchase.id).where(
+                    PremiumTokenPurchase.stripe_checkout_session_id
+                    == str(checkout_session.id)
+                )
+            )
+        ).scalar_one_or_none()
+        if existing_token_purchase is not None:
+            is_token = True
+        else:
+            existing_page_purchase = (
+                await db_session.execute(
+                    select(PagePurchase.id).where(
+                        PagePurchase.stripe_checkout_session_id
+                        == str(checkout_session.id)
+                    )
+                )
+            ).scalar_one_or_none()
+            if existing_page_purchase is None:
+                logger.error(
+                    "finalize_checkout: no purchase row in either table "
+                    "and metadata is empty for session=%s user=%s",
+                    session_id,
+                    user.id,
+                )
+                # Fall through; downstream path will short-circuit on
+                # missing-row + empty-metadata.
+        logger.info(
+            "finalize_checkout: recovered purchase_type=%s for session=%s "
+            "via DB fallback (metadata was empty)",
+            "premium_tokens" if is_token else "page_packs",
+            session_id,
+        )
+
+    is_paid = payment_status in {"paid", "no_payment_required"}
+    is_expired = session_status == "expired"
+
+    if is_paid:
+        if is_token:
+            await _fulfill_completed_token_purchase(db_session, checkout_session)
+        else:
+            await _fulfill_completed_purchase(db_session, checkout_session)
+    elif is_expired:
+        if is_token:
+            await _mark_token_purchase_failed(db_session, str(checkout_session.id))
+        else:
+            await _mark_purchase_failed(db_session, str(checkout_session.id))
+    # Otherwise (e.g. payment_status="unpaid", session_status="open"),
+    # leave the purchase row alone — frontend will keep polling and the
+    # webhook will eventually win the race.
+
+    # Refresh the user row so the response reflects any update applied
+    # by the fulfilment helpers in this same session.
+    await db_session.refresh(user)
+
+    if is_token:
+        purchase = (
+            await db_session.execute(
+                select(PremiumTokenPurchase).where(
+                    PremiumTokenPurchase.stripe_checkout_session_id
+                    == str(checkout_session.id)
+                )
+            )
+        ).scalar_one_or_none()
+        return FinalizeCheckoutResponse(
+            purchase_type="premium_tokens",
+            status=purchase.status.value if purchase else "pending",
+            premium_credit_micros_limit=user.premium_credit_micros_limit,
+            premium_credit_micros_used=user.premium_credit_micros_used,
+            premium_credit_micros_granted=(
+                purchase.credit_micros_granted if purchase else None
+            ),
+        )
+
+    purchase = (
+        await db_session.execute(
+            select(PagePurchase).where(
+                PagePurchase.stripe_checkout_session_id == str(checkout_session.id)
+            )
+        )
+    ).scalar_one_or_none()
+    return FinalizeCheckoutResponse(
+        purchase_type="page_packs",
+        status=purchase.status.value if purchase else "pending",
+        pages_limit=user.pages_limit,
+        pages_used=user.pages_used,
+        pages_granted=purchase.pages_granted if purchase else None,
+    )
+
+
 @router.get("/purchases", response_model=PagePurchaseHistoryResponse)
 async def get_page_purchases(
     user: User = Depends(current_active_user),
@@ -524,7 +757,11 @@ def _get_token_checkout_urls(search_space_id: int) -> tuple[str, str]:
             detail="NEXT_FRONTEND_URL is not configured.",
         )
     base_url = config.NEXT_FRONTEND_URL.rstrip("/")
-    success_url = f"{base_url}/dashboard/{search_space_id}/purchase-success"
+    # See ``_get_checkout_urls`` for why session_id is appended.
+    success_url = (
+        f"{base_url}/dashboard/{search_space_id}/purchase-success"
+        f"?session_id={{CHECKOUT_SESSION_ID}}"
+    )
     cancel_url = f"{base_url}/dashboard/{search_space_id}/purchase-cancel"
     return success_url, cancel_url
 
@@ -575,7 +812,11 @@ async def create_token_checkout_session(
                     "user_id": str(user.id),
                     "quantity": str(body.quantity),
                     "credit_micros_per_unit": str(config.STRIPE_CREDIT_MICROS_PER_UNIT),
-                    "purchase_type": "premium_credit",
+                    # Canonical value matched by ``_is_token_purchase``.
+                    # The legacy ``"premium_credit"`` is still accepted on
+                    # the read side for any in-flight sessions started
+                    # before this rename.
+                    "purchase_type": "premium_tokens",
                 },
             }
         )

surfsense_backend/app/schemas/stripe.py

@@ -56,6 +56,26 @@ class StripeWebhookResponse(BaseModel):
     received: bool = True
 
 
+class FinalizeCheckoutResponse(BaseModel):
+    """Response from /stripe/finalize-checkout.
+
+    Returned by the success page so the UI can show the post-purchase
+    balance immediately, even when the Stripe webhook hasn't been
+    delivered yet. ``status`` mirrors the underlying purchase row
+    (``pending`` / ``completed`` / ``failed``); the FE polls this
+    endpoint until it sees ``completed`` or a final ``failed``.
+    """
+
+    purchase_type: str  # "page_packs" | "premium_tokens"
+    status: str  # PagePurchaseStatus / PremiumTokenPurchaseStatus value
+    pages_limit: int | None = None
+    pages_used: int | None = None
+    pages_granted: int | None = None
+    premium_credit_micros_limit: int | None = None
+    premium_credit_micros_used: int | None = None
+    premium_credit_micros_granted: int | None = None
+
+
 class CreateTokenCheckoutSessionRequest(BaseModel):
     """Request body for creating a premium token purchase checkout session."""
 

surfsense_web/app/dashboard/[search_space_id]/purchase-success/page.tsx

@@ -1,8 +1,9 @@
 "use client";
 
-import { CheckCircle2 } from "lucide-react";
+import { AlertCircle, CheckCircle2, Loader2 } from "lucide-react";
 import Link from "next/link";
-import { useParams } from "next/navigation";
+import { useParams, useSearchParams } from "next/navigation";
+import { useEffect, useRef, useState } from "react";
 import { Button } from "@/components/ui/button";
 import {
 	Card,
@@ -12,23 +13,133 @@ import {
 	CardHeader,
 	CardTitle,
 } from "@/components/ui/card";
+import type { FinalizeCheckoutResponse } from "@/contracts/types/stripe.types";
+import { stripeApiService } from "@/lib/apis/stripe-api.service";
+
+type FinalizeState =
+	| { kind: "loading" }
+	| { kind: "completed"; data: FinalizeCheckoutResponse }
+	| { kind: "pending"; data: FinalizeCheckoutResponse }
+	| { kind: "still_pending"; data: FinalizeCheckoutResponse }
+	| { kind: "failed"; data: FinalizeCheckoutResponse }
+	| { kind: "error"; message: string }
+	| { kind: "no_session" };
+
+const POLL_INTERVAL_MS = 2000;
+const MAX_POLL_ATTEMPTS = 15; // ~30s total before falling back to the still_pending state
 
 export default function PurchaseSuccessPage() {
 	const params = useParams();
+	const searchParams = useSearchParams();
 	const searchSpaceId = String(params.search_space_id ?? "");
+	const sessionId = searchParams.get("session_id");
+
+	const [state, setState] = useState<FinalizeState>(
+		sessionId ? { kind: "loading" } : { kind: "no_session" }
+	);
+	// Tracks active polling so component unmount cancels it
+	const cancelledRef = useRef(false);
+
+	useEffect(() => {
+		if (!sessionId) return;
+
+		cancelledRef.current = false;
+
+		const poll = async (attempt: number): Promise<void> => {
+			if (cancelledRef.current) return;
+			try {
+				const data = await stripeApiService.finalizeCheckout(sessionId);
+				if (cancelledRef.current) return;
+
+				if (data.status === "completed") {
+					setState({ kind: "completed", data });
+					return;
+				}
+				if (data.status === "failed") {
+					setState({ kind: "failed", data });
+					return;
+				}
+
+				// Status is "pending" - either the user paid via async
+				// payment method (Klarna, ACH) or webhook + finalize both
+				// raced and lost. Keep polling up to MAX_POLL_ATTEMPTS,
+				// then fall back to a friendlier message that explains
+				// fulfilment may complete asynchronously.
+				if (attempt < MAX_POLL_ATTEMPTS) {
+					setState({ kind: "pending", data });
+					setTimeout(() => poll(attempt + 1), POLL_INTERVAL_MS);
+				} else {
+					setState({ kind: "still_pending", data });
+				}
+			} catch (err) {
+				if (cancelledRef.current) return;
+				const message = err instanceof Error ? err.message : "Unable to finalize checkout.";
+				setState({ kind: "error", message });
+			}
+		};
+
+		void poll(1);
+
+		return () => {
+			cancelledRef.current = true;
+		};
+	}, [sessionId]);
 
 	return (
 		<div className="flex min-h-[calc(100vh-64px)] items-center justify-center px-4 py-8">
 			<Card className="w-full max-w-lg">
 				<CardHeader className="text-center">
-					<CheckCircle2 className="mx-auto h-10 w-10 text-emerald-500" />
+					{state.kind === "loading" || state.kind === "pending" ? (
-					<CardTitle className="text-2xl">Purchase complete</CardTitle>
+						<Loader2 className="mx-auto h-10 w-10 animate-spin text-primary" />
-					<CardDescription>Your purchase is being applied to your account now.</CardDescription>
+					) : state.kind === "completed" ? (
+						<CheckCircle2 className="mx-auto h-10 w-10 text-emerald-500" />
+					) : (
+						<AlertCircle className="mx-auto h-10 w-10 text-amber-500" />
+					)}
+					<CardTitle className="text-2xl">
+						{state.kind === "loading" && "Confirming payment…"}
+						{state.kind === "pending" && "Processing your payment…"}
+						{state.kind === "still_pending" && "Payment still processing"}
+						{state.kind === "completed" && "Purchase complete"}
+						{state.kind === "failed" && "Purchase failed"}
+						{state.kind === "error" && "Couldn't confirm payment"}
+						{state.kind === "no_session" && "Purchase complete"}
+					</CardTitle>
+					<CardDescription>
+						{state.kind === "loading" && "We're verifying your payment with Stripe."}
+						{state.kind === "pending" &&
+							"Your bank is taking a moment to confirm. This usually takes 5–30 seconds."}
+						{state.kind === "still_pending" &&
+							"Your payment is still being processed by your bank. We'll apply your purchase as soon as it clears — usually within a few minutes. You can safely close this page."}
+						{state.kind === "completed" &&
+							(state.data.purchase_type === "page_packs"
+								? `Added ${formatNumber(state.data.pages_granted ?? 0)} pages to your account.`
+								: `Added ${formatCredit(state.data.premium_credit_micros_granted ?? 0)} of premium credit to your account.`)}
+						{state.kind === "failed" &&
+							"Stripe reported the checkout as failed or expired. Your card was not charged."}
+						{state.kind === "error" &&
+							"Don't worry — if your card was charged, your purchase will still apply within a minute or two."}
+						{state.kind === "no_session" &&
+							"Your purchase is being applied to your account."}
+					</CardDescription>
 				</CardHeader>
 				<CardContent className="space-y-3 text-center">
-					<p className="text-sm text-muted-foreground">
+					{state.kind === "completed" && state.data.purchase_type === "page_packs" && (
-						Your usage meters should refresh automatically in a moment.
+						<p className="text-sm text-muted-foreground">
-					</p>
+							New balance: {formatNumber(state.data.pages_limit ?? 0)} total pages
+							{typeof state.data.pages_used === "number"
+								? ` (${formatNumber((state.data.pages_limit ?? 0) - state.data.pages_used)} remaining)`
+								: ""}
+						</p>
+					)}
+					{state.kind === "completed" && state.data.purchase_type === "premium_tokens" && (
+						<p className="text-sm text-muted-foreground">
+							New premium credit balance: {formatCredit(state.data.premium_credit_micros_limit ?? 0)}
+						</p>
+					)}
+					{state.kind === "error" && (
+						<p className="text-sm text-muted-foreground">{state.message}</p>
+					)}
 				</CardContent>
 				<CardFooter className="flex flex-col gap-2">
 					<Button asChild className="w-full">
@@ -42,3 +153,16 @@ export default function PurchaseSuccessPage() {
 		</div>
 	);
 }
+
+function formatNumber(n: number): string {
+	return new Intl.NumberFormat("en-US").format(n);
+}
+
+function formatCredit(micros: number): string {
+	const dollars = micros / 1_000_000;
+	return new Intl.NumberFormat("en-US", {
+		style: "currency",
+		currency: "USD",
+		maximumFractionDigits: 2,
+	}).format(dollars);
+}

surfsense_web/contracts/types/stripe.types.ts

@@ -73,6 +73,19 @@ export const getTokenPurchasesResponse = z.object({
 	purchases: z.array(tokenPurchase),
 });
 
+// Response from /stripe/finalize-checkout. Either page or token fields
+// are populated depending on purchase_type.
+export const finalizeCheckoutResponse = z.object({
+	purchase_type: z.enum(["page_packs", "premium_tokens"]),
+	status: pagePurchaseStatusEnum,
+	pages_limit: z.number().nullable().optional(),
+	pages_used: z.number().nullable().optional(),
+	pages_granted: z.number().nullable().optional(),
+	premium_credit_micros_limit: z.number().nullable().optional(),
+	premium_credit_micros_used: z.number().nullable().optional(),
+	premium_credit_micros_granted: z.number().nullable().optional(),
+});
+
 export type PagePurchaseStatus = z.infer<typeof pagePurchaseStatusEnum>;
 export type CreateCheckoutSessionRequest = z.infer<typeof createCheckoutSessionRequest>;
 export type CreateCheckoutSessionResponse = z.infer<typeof createCheckoutSessionResponse>;
@@ -85,3 +98,4 @@ export type TokenStripeStatusResponse = z.infer<typeof tokenStripeStatusResponse
 export type TokenPurchaseStatus = z.infer<typeof tokenPurchaseStatusEnum>;
 export type TokenPurchase = z.infer<typeof tokenPurchase>;
 export type GetTokenPurchasesResponse = z.infer<typeof getTokenPurchasesResponse>;
+export type FinalizeCheckoutResponse = z.infer<typeof finalizeCheckoutResponse>;

surfsense_web/lib/apis/stripe-api.service.ts

@@ -5,6 +5,8 @@ import {
 	type CreateTokenCheckoutSessionResponse,
 	createCheckoutSessionResponse,
 	createTokenCheckoutSessionResponse,
+	type FinalizeCheckoutResponse,
+	finalizeCheckoutResponse,
 	type GetPagePurchasesResponse,
 	type GetTokenPurchasesResponse,
 	getPagePurchasesResponse,
@@ -54,6 +56,20 @@ class StripeApiService {
 	getTokenPurchases = async (): Promise<GetTokenPurchasesResponse> => {
 		return baseApiService.get("/api/v1/stripe/token-purchases", getTokenPurchasesResponse);
 	};
+
+	/**
+	 * Synchronously fulfil a checkout session from the success page.
+	 *
+	 * Solves the race where the user lands on /purchase-success before
+	 * Stripe's checkout.session.completed webhook arrives. Idempotent —
+	 * safe to call concurrently with the webhook.
+	 */
+	finalizeCheckout = async (sessionId: string): Promise<FinalizeCheckoutResponse> => {
+		return baseApiService.get(
+			`/api/v1/stripe/finalize-checkout?session_id=${encodeURIComponent(sessionId)}`,
+			finalizeCheckoutResponse
+		);
+	};
 }
 
 export const stripeApiService = new StripeApiService();