.claude/CLAUDE.md

@@ -241,6 +241,29 @@ The native Android app is a Capacitor 8 wrapper of the `ui` SPA, scaffolded unde
 
 - **Monetization** — «Фишка» currency, per-platform wallets, ads. Agreements in
   `docs/PAYMENTS_DECISIONS_ru.md`; a phased plan (E0–E9). go-jet money rule above applies.
+  - **YooKassa (the direct rail since v1.x) does NOT sign its webhooks.** Authenticity is the
+    confirming `GET /v3/payments/{id}` — never the notification body — plus the published sender-IP
+    allowlist. Two extra guards ride on the confirmed object: its `metadata.order_id` must name the
+    order, and its `test` flag must match the shop's `IsTest` (a test-shop payment must never credit
+    real chips). Answer 200 for anything durably decided, 5xx only to be redelivered (YooKassa retries
+    24h).
+  - **YooKassa DOES have a test mode** — a separate *test shop* (own shopId/secret, test cards, up to
+    20 of them), and webhooks/receipts/refunds all work there. The whole rail is verifiable on the
+    contour without real money; don't plan around "no test payments".
+  - **YooKassa has no cabinet-side generic чек.** Unlike Robokassa's cloud kassa, «Чеки от ЮKassa»
+    registers a receipt **only if the request carries `receipt`** — so the itemized receipt is
+    mandatory code on both payment and refund. `payment_subject`/`payment_mode`/`vat_code` are fields
+    *inside* `receipt.items[]` (54-ФЗ tags 1212/1214/1199), documented under the receipts section, not
+    the payment API — easy to miss. A malformed receipt is an API error at payment creation, so it
+    breaks purchases loudly rather than silently skipping the fiscal document.
+  - **The gateway cannot import `backend/internal/*`** (separate module + Go's internal rule), so a
+    security list shared by both hops either lives in `pkg/` or is enforced backend-side. The YooKassa
+    sender allowlist is enforced in the backend, with the gateway forwarding the real peer IP as
+    `X-Forwarded-For` — do not duplicate the CIDR list into the gateway.
+  - **Robokassa is retired but wired.** The direct rail resolves YooKassa → else Robokassa, and no
+    deployment sets the Robokassa credentials. Reviving it is a credentials change, not a code change;
+    `backend/internal/robokassa/README.md` holds the retired vars, cabinet URLs and the known gap
+    (the per-channel `…_WEB_*`/`…_ANDROID_*` vars never reached any workflow).
   - **VK payment title trap:** a product title with an HTML-special char (`& < > " '`) silently kills
     VK purchases. VK HTML-escapes it in the `order_status_change` callback echo (`"`→`&quot;`) but
     signs a different form → the gateway logs `vk callback: bad signature` and rejects it (get_item

.gitea/workflows/ci.yaml

@@ -371,13 +371,14 @@ jobs:
           SMTP_RELAY_HOST: ${{ vars.SMTP_RELAY_HOST }}
           SMTP_RELAY_PORT: ${{ vars.SMTP_RELAY_PORT }}
           SMTP_RELAY_TLS: ${{ vars.SMTP_RELAY_TLS }}
-          # Direct-rail (Robokassa) sandbox intake on the contour: the test shop's merchant login +
-          # Password1/Password2. IsTest is forced to 1 below so the contour can never take real money
-          # (independent of the shop's own mode). Empty login leaves the direct rail off.
-          ROBOKASSA_MERCHANT_LOGIN: ${{ secrets.TEST_BACKEND_ROBOKASSA_MERCHANT_LOGIN }}
-          ROBOKASSA_PASSWORD1: ${{ secrets.TEST_BACKEND_ROBOKASSA_PASSWORD1 }}
-          ROBOKASSA_PASSWORD2: ${{ secrets.TEST_BACKEND_ROBOKASSA_PASSWORD2 }}
-          ROBOKASSA_TEST: "1"
+          # Direct-rail (YooKassa) intake on the contour: the credentials of a YooKassa TEST shop,
+          # which takes test cards and moves no real money. YOOKASSA_WEB_TEST is forced to 1 so the
+          # contour refuses to credit anything but a test payment, whatever credentials are set.
+          # Empty credentials leave the direct rail off.
+          YOOKASSA_WEB_SHOP_ID: ${{ secrets.TEST_BACKEND_YOOKASSA_WEB_SHOP_ID }}
+          YOOKASSA_WEB_SECRET_KEY: ${{ secrets.TEST_BACKEND_YOOKASSA_WEB_SECRET_KEY }}
+          YOOKASSA_WEB_TEST: "1"
+          YOOKASSA_VAT_CODE: ${{ vars.TEST_BACKEND_YOOKASSA_VAT_CODE }}
           SMTP_RELAY_FROM: ${{ vars.TEST_SMTP_RELAY_FROM }}
           # Operator alerts: backend admin emails (new feedback / complaints) + Grafana
           # infra alerts. Distinct senders + recipients; Grafana uses the relay's STARTTLS
@@ -576,15 +577,16 @@ jobs:
       - name: Probe the /pay/ callback route reaches the gateway
         run: |
           set -u
-          # /pay/robokassa/result must reach the gateway, not fall to the landing catch-all. An
-          # unsigned probe is rejected downstream, so the gateway answers a 4xx/5xx (never a 200 or
-          # a 404 landing.html), which proves the edge route is wired.
-          out="$(docker run --rm --network edge alpine:3.20 wget -S -q -O /dev/null http://scrabble/pay/robokassa/result 2>&1 || true)"
+          # /pay/yookassa/notify must reach the gateway, not fall to the landing catch-all. The probe
+          # is a bare GET from an address that is not one of YooKassa's senders, so it is rejected
+          # downstream and the gateway answers a 4xx/5xx (never a 200 or a 404 landing.html), which
+          # proves the edge route is wired.
+          out="$(docker run --rm --network edge alpine:3.20 wget -S -q -O /dev/null http://scrabble/pay/yookassa/notify 2>&1 || true)"
           echo "$out" | grep -E "HTTP/" || true
           if echo "$out" | grep -qE "HTTP/1\.1 (4|5)[0-9][0-9]"; then
             echo "ok: /pay/ reaches the gateway (non-landing response)"
           else
-            echo "FAIL: /pay/robokassa/result did not reach the gateway (landing catch-all?)"
+            echo "FAIL: /pay/yookassa/notify did not reach the gateway (landing catch-all?)"
             docker logs --tail 50 scrabble-gateway || true
             exit 1
           fi

.gitea/workflows/prod-deploy.yaml

@@ -99,14 +99,18 @@ jobs:
       GRAFANA_ADMIN_PASSWORD: ${{ secrets.PROD_GRAFANA_ADMIN_PASSWORD }}
       TELEGRAM_BOT_TOKEN: ${{ secrets.PROD_TELEGRAM_BOT_TOKEN }}
       GATEWAY_VK_APP_SECRET: ${{ secrets.GATEWAY_VK_APP_SECRET }}
-      # Robokassa direct-rail (backend BACKEND_ROBOKASSA_*): the prod shop login + the pass phrases
-      # that sign the launch request / verify the Result callback, and the test-mode flag — a var so
-      # go-live is a flag flip, not a secret redeploy ("1" runs test payments against the test
-      # passwords; empty/"0" is live). An empty login leaves the direct rail disabled.
-      ROBOKASSA_MERCHANT_LOGIN: ${{ secrets.PROD_BACKEND_ROBOKASSA_MERCHANT_LOGIN }}
-      ROBOKASSA_PASSWORD1: ${{ secrets.PROD_BACKEND_ROBOKASSA_PASSWORD1 }}
-      ROBOKASSA_PASSWORD2: ${{ secrets.PROD_BACKEND_ROBOKASSA_PASSWORD2 }}
-      ROBOKASSA_TEST: ${{ vars.PROD_BACKEND_ROBOKASSA_TEST }}
+      # YooKassa direct rail (backend BACKEND_YOOKASSA_*), one merchant shop per channel: the shop
+      # id + secret key, and a test-shop flag — a var, so pointing prod at a test shop is a flag
+      # flip rather than a secret rotation ("1" refuses to credit anything but a test payment;
+      # empty/"0" is live). Empty credentials leave that channel — or the whole rail — disabled.
+      # The VAT rate code on every receipt line is a var too, so a rate change needs no code change.
+      YOOKASSA_WEB_SHOP_ID: ${{ secrets.PROD_BACKEND_YOOKASSA_WEB_SHOP_ID }}
+      YOOKASSA_WEB_SECRET_KEY: ${{ secrets.PROD_BACKEND_YOOKASSA_WEB_SECRET_KEY }}
+      YOOKASSA_WEB_TEST: ${{ vars.PROD_BACKEND_YOOKASSA_WEB_TEST }}
+      YOOKASSA_ANDROID_SHOP_ID: ${{ secrets.PROD_BACKEND_YOOKASSA_ANDROID_SHOP_ID }}
+      YOOKASSA_ANDROID_SECRET_KEY: ${{ secrets.PROD_BACKEND_YOOKASSA_ANDROID_SECRET_KEY }}
+      YOOKASSA_ANDROID_TEST: ${{ vars.PROD_BACKEND_YOOKASSA_ANDROID_TEST }}
+      YOOKASSA_VAT_CODE: ${{ vars.PROD_BACKEND_YOOKASSA_VAT_CODE }}
       # VK ID web login: the "Web" app id (the gateway reuses it as GATEWAY_VK_ID_APP_ID at
       # runtime) + the app's protected key. Both shared across contours. The redirect URL is
       # derived from PUBLIC_BASE_URL in deploy/write-prod-env.sh.

.gitea/workflows/prod-rollback.yaml

@@ -61,12 +61,15 @@ jobs:
       # the SAME env.sh (email / VK login / Grafana alerts survive a rollback). TELEGRAM_MINIAPP_URL
       # and GRAFANA_ROOT_URL are derived from PUBLIC_BASE_URL in deploy/write-prod-env.sh.
       GATEWAY_VK_APP_SECRET: ${{ secrets.GATEWAY_VK_APP_SECRET }}
-      # Robokassa direct-rail: the rollback re-renders the same runtime env (write-prod-env.sh), so
+      # YooKassa direct rail: the rollback re-renders the same runtime env (write-prod-env.sh), so
       # it must carry the same credentials or the direct rail goes dark after a rollback.
-      ROBOKASSA_MERCHANT_LOGIN: ${{ secrets.PROD_BACKEND_ROBOKASSA_MERCHANT_LOGIN }}
-      ROBOKASSA_PASSWORD1: ${{ secrets.PROD_BACKEND_ROBOKASSA_PASSWORD1 }}
-      ROBOKASSA_PASSWORD2: ${{ secrets.PROD_BACKEND_ROBOKASSA_PASSWORD2 }}
-      ROBOKASSA_TEST: ${{ vars.PROD_BACKEND_ROBOKASSA_TEST }}
+      YOOKASSA_WEB_SHOP_ID: ${{ secrets.PROD_BACKEND_YOOKASSA_WEB_SHOP_ID }}
+      YOOKASSA_WEB_SECRET_KEY: ${{ secrets.PROD_BACKEND_YOOKASSA_WEB_SECRET_KEY }}
+      YOOKASSA_WEB_TEST: ${{ vars.PROD_BACKEND_YOOKASSA_WEB_TEST }}
+      YOOKASSA_ANDROID_SHOP_ID: ${{ secrets.PROD_BACKEND_YOOKASSA_ANDROID_SHOP_ID }}
+      YOOKASSA_ANDROID_SECRET_KEY: ${{ secrets.PROD_BACKEND_YOOKASSA_ANDROID_SECRET_KEY }}
+      YOOKASSA_ANDROID_TEST: ${{ vars.PROD_BACKEND_YOOKASSA_ANDROID_TEST }}
+      YOOKASSA_VAT_CODE: ${{ vars.PROD_BACKEND_YOOKASSA_VAT_CODE }}
       VITE_VK_APP_ID: ${{ vars.VITE_VK_APP_ID }}
       GATEWAY_VK_ID_CLIENT_SECRET: ${{ secrets.GATEWAY_VK_ID_CLIENT_SECRET }}
       GATEWAY_HONEYTOKEN: ${{ secrets.PROD_GATEWAY_HONEYTOKEN }}

PLAN.md

@@ -3,7 +3,7 @@
 Technical, step-by-step implementation of the monetization domain. Business mechanics and
 the rationale for every rule live in [`docs/PAYMENTS.md`](docs/PAYMENTS.md) (RU mirror
 [`docs/PAYMENTS_ru.md`](docs/PAYMENTS_ru.md)); the frozen owner agreements they both derive
-from (the `D1`–`D41` decisions log) live in
+from (the `D1`–`D51` decisions log) live in
 [`docs/PAYMENTS_DECISIONS_ru.md`](docs/PAYMENTS_DECISIONS_ru.md) — the authority when a rule
 is disputed. This file is the *how*. Each stage is written to be self-sufficient: returning
 to it gives full context — goal, exact touch-points, tests, done-criteria, and current
@@ -11,7 +11,7 @@ status — without re-deriving decisions.
 
 ## How to use this file
 
-- **Stage granularity (E0–E9) is fixed.** Do not split or merge stages. Plan each stage
+- **Stage granularity (E0–E12) is fixed.** Do not split or merge stages. Plan each stage
   densely enough to execute whole.
 - **Never leak stage ids into the product.** Code, comments, commit messages, PR
   titles/descriptions must read as finalized feature copy — never "E5", "stage 3", etc.
@@ -41,6 +41,7 @@ status — without re-deriving decisions.
 | E9 | Tournament fee | future | TODO |
 | E10 | Multi-shop direct rail + ИП fiscalization | 2+ | DONE |
 | E11 | Payment availability kill switch + per-account override | 2 | DONE |
+| E12 | YooKassa direct rail (Robokassa retired) | 2+ | DONE |
 
 **Release 1** = full mechanics with no real money, exercised via `admin_grant` (E0→E1→E2→E3).
 **Release 2** = money (E4→E5→E6→E7). E8 is standalone (game-behaviour change, can run in
@@ -1012,6 +1013,55 @@ so nothing is disabled until an operator acts.
 
 ---
 
+## E12 — YooKassa direct rail (Robokassa retired)
+
+**Status:** DONE · **Release 2+ (money-live)** · depends on: E5 (intake/`Fund`, the order flow), E7
+(the admin refund + report), E10 (per-channel shops), E11 (the kill switch) · mechanics: PAYMENTS §2,
+§9, §11, §12; decisions D47–D51 (revising D41).
+
+**Delivered.** The `direct` (RUB) rail settles through **YooKassa** instead of Robokassa. The wallet
+model is untouched — one `direct` segment, the same spend wall, the same per-channel shops (D42) and
+`shop` on the order (D44). Robokassa is **dormant, not deleted**: the direct rail falls back to it
+when no YooKassa shop is configured, so reviving it is a credentials change (D47).
+
+- **Provider glue** — `backend/internal/yookassa`: an API client (`CreatePayment` / `GetPayment` /
+  `CreateRefund`, HTTP Basic, `Idempotence-Key`), a per-channel `Shops` registry with `ByShopID` for
+  attributing a notification, the notification envelope + the sender-IP allowlist, and the fiscal
+  receipt builder. No DB, no payments-domain coupling — the same shape as the `robokassa` package.
+- **Order** — `handleWalletOrder` prefers a YooKassa shop and otherwise falls through to Robokassa.
+  It creates the payment (order id as both `Idempotence-Key` and `metadata.order_id`), records the
+  provider payment id on the order (`AttachProviderPayment`; no migration — the column existed) and
+  returns `confirmation_url`. D36's email anchor now also feeds the receipt (`ConfirmedEmail`).
+- **Notification** — `/pay/yookassa/notify` (gateway: rate limit + raw-body proxy; backend: sender
+  allowlist, then the confirming `GetPayment`). Nothing in the body is acted on (D48). Guards: the
+  payment's metadata must name the order, and its `test` flag must match the shop's. `payment.canceled`
+  records a `failed` event. 200 = durably decided, 5xx = redeliver.
+- **Reconcile** — `runOrderReaper` asks the provider about each pending order that reached its expiry
+  age carrying a payment id, and credits the ones really paid (D49). One request per order.
+- **Refund** — the `/_gm` button calls `POST /v3/refunds` first and records only on success, under the
+  provider's own refund id (D50); a failure records nothing.
+- **Fiscalization** — «Чеки от ЮKassa» with the `receipt` sent from code (D51), reversing E10's B4:
+  YooKassa has no cabinet-side generic receipt. `BACKEND_YOOKASSA_VAT_CODE` is a deploy variable;
+  the settlement subject/method are constants.
+- **Config/deploy** — `BACKEND_YOOKASSA_{WEB,ANDROID}_{SHOP_ID,SECRET_KEY,TEST}` +
+  `BACKEND_YOOKASSA_VAT_CODE`; every `ROBOKASSA_*` mapping removed from compose, `.env.example`,
+  `write-prod-env.sh` and the three workflows, and recorded in `backend/internal/robokassa/README.md`.
+  The CI edge probe now targets `/pay/yookassa/notify`.
+- **Tests** — unit (`yookassa`: request building, receipt, idempotence key, error retryability, shop
+  registry, IP allowlist); integration (`payments_yookassa_test.go`: credit-once + redelivery, a
+  forged notification credits nothing, a foreign sender is refused, a live payment on a test shop is
+  refused, a decline records `failed`, the reconcile sweep credits a lost notification and leaves an
+  unpaid order alone, the refund moves money then records — and records nothing when it fails, the
+  order path mints a payment with a receipt, and D36 still gates the rail).
+
+**Contour-safe:** no migration, no wire change; the client is rail-agnostic (only the mock URL and an
+e2e assertion name a provider).
+
+**Verified on the contour** against a YooKassa **test shop** (test mode exists — a separate test shop
+with its own credentials and test cards), then in prod with one real payment.
+
+---
+
 ## Verification & CI (all stages)
 
 - Per-stage tests at the layers above; **compliance-gate regression is mandatory** (a

backend/cmd/backend/main.go

@@ -335,7 +335,11 @@ func run(ctx context.Context, cfg config.Config, logger *zap.Logger) error {
 		Notifier:      hub,
 		ExportSignKey: cfg.ExportSignKey,
 		Renderer:      renderer,
-		Robokassa:     cfg.Robokassa,
+		YooKassa:      cfg.YooKassa,
+
+		YooKassaVatCode: cfg.YooKassaVatCode,
+		PublicBaseURL:   cfg.PublicBaseURL,
+		Robokassa:       cfg.Robokassa,
 	})
 	pushSrv := pushgrpc.NewServer(cfg.GRPCAddr, hub, logger)
 
@@ -345,8 +349,8 @@ func run(ctx context.Context, cfg config.Config, logger *zap.Logger) error {
 		zap.String("http_addr", cfg.HTTPAddr),
 		zap.String("grpc_addr", cfg.GRPCAddr))
 	// Sweep expired pending payment orders on a cadence (cosmetic hygiene; a late valid callback
-	// still credits). Runs until ctx is cancelled.
-	go runOrderReaper(ctx, paymentsSvc, logger)
+	// still credits), asking the provider about each one first. Runs until ctx is cancelled.
+	go runOrderReaper(ctx, paymentsSvc, srv, logger)
 	// Deliver pending payment_events to connected clients as an in-app wallet-refresh push (the
 	// credit already landed in the ledger; a return-focus poll is the client-side fallback).
 	go runPaymentDispatcher(ctx, paymentsSvc, hub, logger)
@@ -363,7 +367,12 @@ func run(ctx context.Context, cfg config.Config, logger *zap.Logger) error {
 // runOrderReaper periodically expires pending payment orders past their configured lifetime, until
 // ctx is cancelled. Expiry is cosmetic: a later valid provider callback still credits an expired
 // order.
-func runOrderReaper(ctx context.Context, p *payments.Service, log *zap.Logger) {
+//
+// Before writing an order off it asks the provider what really happened to it — the one status check
+// each order gets, and the safety net for a notification that was lost for good (YooKassa redelivers
+// for 24 hours, so only a permanently lost one reaches here). A rail with no such check contributes
+// nothing to this pass.
+func runOrderReaper(ctx context.Context, p *payments.Service, srv *server.Server, log *zap.Logger) {
 	t := time.NewTicker(5 * time.Minute)
 	defer t.Stop()
 	for {
@@ -371,6 +380,9 @@ func runOrderReaper(ctx context.Context, p *payments.Service, log *zap.Logger) {
 		case <-ctx.Done():
 			return
 		case <-t.C:
+			if n := srv.ReconcileYooKassaOrders(ctx); n > 0 {
+				log.Info("order reaper: credited orders confirmed by the provider", zap.Int("count", n))
+			}
 			if n, err := p.ExpireOrders(ctx); err != nil {
 				log.Warn("order reaper: sweep failed", zap.Error(err))
 			} else if n > 0 {

backend/internal/account/account.go

@@ -397,16 +397,24 @@ func (s *Store) Identities(ctx context.Context, accountID uuid.UUID) ([]Identity
 // HasConfirmedEmail reports whether the account owns a confirmed email identity — the direct-rail
 // recovery anchor a first purchase requires (D36).
 func (s *Store) HasConfirmedEmail(ctx context.Context, accountID uuid.UUID) (bool, error) {
+	_, ok, err := s.ConfirmedEmail(ctx, accountID)
+	return ok, err
+}
+
+// ConfirmedEmail returns the account's confirmed email address, the oldest one first when several
+// exist. Besides being the direct-rail recovery anchor (D36) it is where the rail's fiscal receipt
+// is delivered, so the purchase path reads the address itself rather than only its presence.
+func (s *Store) ConfirmedEmail(ctx context.Context, accountID uuid.UUID) (string, bool, error) {
 	ids, err := s.Identities(ctx, accountID)
 	if err != nil {
-		return false, err
+		return "", false, err
 	}
 	for _, id := range ids {
 		if id.Kind == "email" && id.Confirmed {
-			return true, nil
+			return id.ExternalID, true, nil
 		}
 	}
-	return false, nil
+	return "", false, nil
 }
 
 // ListAccounts returns accounts for the admin user list, newest first, paginated

backend/internal/config/config.go

@@ -17,6 +17,7 @@ import (
 	"scrabble/backend/internal/robokassa"
 	"scrabble/backend/internal/robot"
 	"scrabble/backend/internal/telemetry"
+	"scrabble/backend/internal/yookassa"
 )
 
 // Config holds the backend's runtime configuration.
@@ -65,8 +66,17 @@ type Config struct {
 	// RendererURL is the base URL of the internal image-render sidecar (e.g.
 	// http://renderer:8090). Empty disables the PNG export artifact.
 	RendererURL string
-	// Robokassa configures the direct-rail (RUB) payment provider — one merchant shop per channel
-	// (D42). An empty set leaves the direct order and Result-callback endpoints unregistered.
+	// YooKassa configures the direct-rail (RUB) payment provider — one merchant shop per channel
+	// (D42). An empty set leaves the direct order and notification endpoints unregistered and falls
+	// the direct rail back to Robokassa.
+	YooKassa yookassa.Shops
+	// YooKassaVatCode is the VAT rate code stamped on every fiscal receipt line (54-ФЗ tag 1199).
+	// It is configurable because the rate is the one receipt attribute that genuinely changes.
+	YooKassaVatCode int
+	// Robokassa configures the retired direct-rail payment provider — one merchant shop per channel
+	// (D42). It is dormant: no deployment sets its credentials, so the set is empty and the rail
+	// resolves to YooKassa. Kept wired so restoring Robokassa is a credentials change, not a code
+	// change — see backend/internal/robokassa/README.md.
 	Robokassa robokassa.Shops
 }
 
@@ -158,9 +168,26 @@ func Load() (Config, error) {
 		AdminTo:   os.Getenv("BACKEND_ADMIN_EMAIL"),
 	}
 
-	// Robokassa direct rail: one merchant shop per channel (D42). The legacy single-shop vars seed
-	// the web channel so existing deploys keep working; the per-channel vars add the rest. A shop
-	// with no MerchantLogin is dropped (the rail stays dormant when none is configured).
+	// YooKassa direct rail: one merchant shop per channel (D42). A shop missing either credential is
+	// dropped, so the rail stays dormant until a channel is fully configured.
+	ykShops := yookassa.Shops{}
+	for channel, prefix := range map[string]string{
+		yookassa.ChannelWeb:     "BACKEND_YOOKASSA_WEB",
+		yookassa.ChannelAndroid: "BACKEND_YOOKASSA_ANDROID",
+	} {
+		if shop := yookassaShop(prefix); shop.Configured() {
+			ykShops[channel] = shop
+		}
+	}
+	vatCode, err := envInt("BACKEND_YOOKASSA_VAT_CODE", yookassa.VatCodeNone)
+	if err != nil {
+		return Config{}, err
+	}
+
+	// Robokassa direct rail: retired but kept wired (see backend/internal/robokassa/README.md). No
+	// deployment sets these, so the set is empty and the direct rail resolves to YooKassa; restoring
+	// the credentials revives it without a code change. The legacy single-shop vars seed the web
+	// channel; the per-channel vars add the rest.
 	shops := robokassa.Shops{}
 	web := robokassaShop("BACKEND_ROBOKASSA_WEB")
 	if web.MerchantLogin == "" {
@@ -190,6 +217,8 @@ func Load() (Config, error) {
 		GuestRetention:    guestRetention,
 		ExportSignKey:     os.Getenv("BACKEND_EXPORT_SIGN_KEY"),
 		RendererURL:       os.Getenv("BACKEND_RENDERER_URL"),
+		YooKassa:          ykShops,
+		YooKassaVatCode:   vatCode,
 		Robokassa:         shops,
 	}
 	if err := c.validate(); err != nil {
@@ -248,6 +277,19 @@ func (c Config) validate() error {
 			return fmt.Errorf("config: robokassa shop %q: password1 and password2 must be set when its merchant login is", channel)
 		}
 	}
+	if !yookassa.ValidVatCode(c.YooKassaVatCode) {
+		return fmt.Errorf("config: BACKEND_YOOKASSA_VAT_CODE %d is not a 54-ФЗ VAT rate code (1..%d)", c.YooKassaVatCode, yookassa.VatCodeMax)
+	}
+	if c.YooKassa.Configured() {
+		// The YooKassa rail sends the customer to a hosted payment page and needs an absolute return
+		// URL to bring them back, which only the public base URL can supply.
+		if c.PublicBaseURL == "" {
+			return fmt.Errorf("config: BACKEND_PUBLIC_BASE_URL must be set when a YooKassa shop is configured")
+		}
+		if u, err := url.Parse(c.PublicBaseURL); err != nil || u.Scheme == "" || u.Host == "" {
+			return fmt.Errorf("config: BACKEND_PUBLIC_BASE_URL %q must be an absolute URL (scheme://host)", c.PublicBaseURL)
+		}
+	}
 	return nil
 }
 
@@ -288,6 +330,18 @@ func envDuration(key string, fallback time.Duration) (time.Duration, error) {
 	return d, nil
 }
 
+// yookassaShop reads a YooKassa shop's credentials from the environment under prefix (e.g.
+// "BACKEND_YOOKASSA_WEB" → _SHOP_ID / _SECRET_KEY / _TEST). _TEST marks a test shop, which lets the
+// intake refuse to credit a live payment against test credentials and vice versa. A shop missing
+// either credential yields a Config the caller drops.
+func yookassaShop(prefix string) yookassa.Config {
+	return yookassa.Config{
+		ShopID:    os.Getenv(prefix + "_SHOP_ID"),
+		SecretKey: os.Getenv(prefix + "_SECRET_KEY"),
+		IsTest:    os.Getenv(prefix+"_TEST") == "1",
+	}
+}
+
 // robokassaShop reads a Robokassa shop's four credentials from the environment under prefix (e.g.
 // "BACKEND_ROBOKASSA_WEB" → _MERCHANT_LOGIN / _PASSWORD1 / _PASSWORD2 / _TEST). A missing
 // MerchantLogin yields a zero Config the caller drops.

backend/internal/inttest/payments_yookassa_test.go

@@ -0,0 +1,504 @@
+//go:build integration
+
+package inttest
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"sync"
+	"testing"
+
+	"github.com/google/uuid"
+	"go.uber.org/zap"
+
+	"scrabble/backend/internal/account"
+	"scrabble/backend/internal/payments"
+	"scrabble/backend/internal/server"
+	"scrabble/backend/internal/yookassa"
+)
+
+// The test shop the fake API answers for. IsTest is true throughout, matching a YooKassa test shop.
+const (
+	ykShopID    = "100500"
+	ykSecretKey = "test_secret"
+	// ykSenderIP is inside YooKassa's published notification ranges; the intake rejects anything else.
+	ykSenderIP = "185.71.76.1"
+)
+
+// fakeYooKassa is a stand-in for the YooKassa API. Tests set the payment it reports and whether a
+// refund succeeds, then assert on what the intake did with that answer.
+type fakeYooKassa struct {
+	mu sync.Mutex
+	// payments answers GET /payments/{id}; a missing id is a 404, as it is for a payment we never made.
+	payments map[string]yookassa.Payment
+	// refundFails makes POST /refunds answer 500, standing in for a provider that did not move money.
+	refundFails bool
+	// refundCalls counts the refunds actually requested.
+	refundCalls int
+	// createdIdempotenceKey records the key sent on the last create-payment call.
+	createdIdempotenceKey string
+	// lastReceipt records the receipt object of the last create-payment call.
+	lastReceipt map[string]any
+}
+
+// newFakeYooKassa starts the fake API and returns it with a shop config pointed at it.
+func newFakeYooKassa(t *testing.T) (*fakeYooKassa, yookassa.Config) {
+	t.Helper()
+	f := &fakeYooKassa{payments: map[string]yookassa.Payment{}}
+	srv := httptest.NewServer(http.HandlerFunc(f.serve))
+	t.Cleanup(srv.Close)
+	return f, yookassa.Config{ShopID: ykShopID, SecretKey: ykSecretKey, IsTest: true, BaseURL: srv.URL}
+}
+
+func (f *fakeYooKassa) serve(w http.ResponseWriter, r *http.Request) {
+	f.mu.Lock()
+	defer f.mu.Unlock()
+	w.Header().Set("Content-Type", "application/json")
+	switch {
+	case r.Method == http.MethodPost && r.URL.Path == "/payments":
+		var body struct {
+			Amount   yookassa.Amount   `json:"amount"`
+			Metadata map[string]string `json:"metadata"`
+			Receipt  map[string]any    `json:"receipt"`
+		}
+		_ = json.NewDecoder(r.Body).Decode(&body)
+		f.createdIdempotenceKey = r.Header.Get("Idempotence-Key")
+		f.lastReceipt = body.Receipt
+		id := "pay-" + body.Metadata[yookassa.MetadataOrderID]
+		p := yookassa.Payment{
+			ID: id, Status: yookassa.StatusPending, Test: true, Amount: body.Amount,
+			Confirmation: yookassa.Confirmation{Type: yookassa.ConfirmationRedirect, ConfirmationURL: "https://yoomoney.test/pay/" + id},
+			Metadata:     body.Metadata,
+			Recipient:    yookassa.Recipient{AccountID: ykShopID},
+		}
+		f.payments[id] = p
+		_ = json.NewEncoder(w).Encode(p)
+	case r.Method == http.MethodGet && strings.HasPrefix(r.URL.Path, "/payments/"):
+		p, ok := f.payments[strings.TrimPrefix(r.URL.Path, "/payments/")]
+		if !ok {
+			w.WriteHeader(http.StatusNotFound)
+			_, _ = w.Write([]byte(`{"type":"error","description":"not found"}`))
+			return
+		}
+		_ = json.NewEncoder(w).Encode(p)
+	case r.Method == http.MethodPost && r.URL.Path == "/refunds":
+		if f.refundFails {
+			w.WriteHeader(http.StatusInternalServerError)
+			_, _ = w.Write([]byte(`{"type":"error","description":"acquirer unavailable"}`))
+			return
+		}
+		f.refundCalls++
+		var body yookassa.RefundRequest
+		_ = json.NewDecoder(r.Body).Decode(&body)
+		_ = json.NewEncoder(w).Encode(yookassa.Refund{
+			ID: "refund-1", Status: yookassa.StatusSucceeded, PaymentID: body.PaymentID, Amount: body.Amount,
+		})
+	default:
+		w.WriteHeader(http.StatusNotFound)
+	}
+}
+
+// setPayment overwrites what the API reports for a payment — how a test says "the money did (or did
+// not) really move", independently of what a notification claims.
+func (f *fakeYooKassa) setPayment(id string, mutate func(p *yookassa.Payment)) {
+	f.mu.Lock()
+	defer f.mu.Unlock()
+	p := f.payments[id]
+	p.ID = id
+	mutate(&p)
+	f.payments[id] = p
+}
+
+// yookassaServer builds a backend server whose direct rail is the fake YooKassa shop.
+//
+// The suite shares one database, and the kill-switch test leaves the direct rail disabled, so the
+// rail status is reset first: these tests are about the provider, not about ops availability, and
+// fail-open means an absent row is an enabled rail.
+func yookassaServer(t *testing.T, shop yookassa.Config) (*server.Server, *payments.Service) {
+	t.Helper()
+	if _, err := testDB.ExecContext(context.Background(),
+		`DELETE FROM payments.rail_status WHERE rail LIKE 'direct%'`); err != nil {
+		t.Fatalf("reset direct rail status: %v", err)
+	}
+	paySvc := newPaymentsService()
+	srv := server.New(":0", server.Deps{
+		Logger:          zap.NewNop(),
+		Accounts:        account.NewStore(testDB),
+		Games:           newGameService(),
+		Registry:        testRegistry,
+		DictDir:         dictDir(),
+		Payments:        paySvc,
+		YooKassa:        yookassa.Shops{yookassa.ChannelWeb: shop},
+		YooKassaVatCode: yookassa.VatCodeNone,
+		PublicBaseURL:   "https://scrabble.test",
+	})
+	return srv, paySvc
+}
+
+// postYooKassaNotify posts a notification body to the intake as the given sender, and reports the status code.
+func postYooKassaNotify(t *testing.T, srv *server.Server, senderIP, event, paymentID, orderID string) int {
+	t.Helper()
+	body := fmt.Sprintf(`{"type":"notification","event":%q,"object":{"id":%q,"status":"succeeded",
+		"recipient":{"account_id":%q},"metadata":{"order_id":%q}}}`, event, paymentID, ykShopID, orderID)
+	req := httptest.NewRequest(http.MethodPost, "/api/v1/internal/payments/yookassa/notify", strings.NewReader(body))
+	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("X-Forwarded-For", senderIP)
+	rec := httptest.NewRecorder()
+	srv.Handler().ServeHTTP(rec, req)
+	return rec.Code
+}
+
+// seedYooKassaOrder opens a paid-for-real order: a pending order with the provider payment id
+// attached, exactly as the order path leaves it once YooKassa has minted the payment.
+func seedYooKassaOrder(t *testing.T, f *fakeYooKassa, pay *payments.Service, acc uuid.UUID) (uuid.UUID, string) {
+	t.Helper()
+	ctx := context.Background()
+	prod := seedPackProduct(t, 100, methodPrice{method: "direct", currency: "RUB", amount: 14900})
+	res, err := pay.CreateOrder(ctx, acc, payments.NewContext("direct", "web"), []payments.Source{payments.SourceDirect}, prod, "yookassa")
+	if err != nil {
+		t.Fatalf("create order: %v", err)
+	}
+	paymentID := "pay-" + res.OrderID.String()
+	f.setPayment(paymentID, func(p *yookassa.Payment) {
+		p.Status = yookassa.StatusSucceeded
+		p.Paid = true
+		p.Test = true
+		p.Amount = yookassa.Amount{Value: "149.00", Currency: "RUB"}
+		p.Metadata = map[string]string{yookassa.MetadataOrderID: res.OrderID.String()}
+		p.Recipient = yookassa.Recipient{AccountID: ykShopID}
+	})
+	if err := pay.AttachProviderPayment(ctx, res.OrderID, "yookassa", paymentID); err != nil {
+		t.Fatalf("attach provider payment: %v", err)
+	}
+	return res.OrderID, paymentID
+}
+
+// TestYooKassaNotifyCreditsOnce drives the crediting path: a succeeded notification credits the
+// order exactly once, and a redelivery credits nothing more.
+func TestYooKassaNotifyCreditsOnce(t *testing.T) {
+	f, shop := newFakeYooKassa(t)
+	srv, pay := yookassaServer(t, shop)
+	acc := provisionAccount(t)
+	orderID, paymentID := seedYooKassaOrder(t, f, pay, acc)
+
+	if code := postYooKassaNotify(t, srv, ykSenderIP, yookassa.EventPaymentSucceeded, paymentID, orderID.String()); code != http.StatusOK {
+		t.Fatalf("notify = %d, want 200", code)
+	}
+	if got := readBalance(t, acc, "direct"); got != 100 {
+		t.Errorf("balance = %d, want 100", got)
+	}
+	if orderStatus(t, orderID) != "paid" {
+		t.Errorf("order status = %s, want paid", orderStatus(t, orderID))
+	}
+
+	// YooKassa redelivers until it gets a 200; a redelivery must credit nothing and still answer 200.
+	if code := postYooKassaNotify(t, srv, ykSenderIP, yookassa.EventPaymentSucceeded, paymentID, orderID.String()); code != http.StatusOK {
+		t.Fatalf("redelivered notify = %d, want 200", code)
+	}
+	if got := readBalance(t, acc, "direct"); got != 100 {
+		t.Errorf("balance after redelivery = %d, want 100 (credited once)", got)
+	}
+	if ledgerRows(t, acc, "fund") != 1 {
+		t.Errorf("fund ledger rows = %d, want 1", ledgerRows(t, acc, "fund"))
+	}
+}
+
+// TestYooKassaNotifyIsNotEvidence is the security property of the whole rail: notifications are
+// unsigned, so a fabricated "succeeded" credits nothing when the confirming read says otherwise.
+func TestYooKassaNotifyIsNotEvidence(t *testing.T) {
+	f, shop := newFakeYooKassa(t)
+	srv, pay := yookassaServer(t, shop)
+	acc := provisionAccount(t)
+	orderID, paymentID := seedYooKassaOrder(t, f, pay, acc)
+
+	// The provider says the payment never completed, whatever the notification claims.
+	f.setPayment(paymentID, func(p *yookassa.Payment) { p.Status = yookassa.StatusPending; p.Paid = false })
+	if code := postYooKassaNotify(t, srv, ykSenderIP, yookassa.EventPaymentSucceeded, paymentID, orderID.String()); code != http.StatusOK {
+		t.Fatalf("notify = %d, want 200", code)
+	}
+	if got := readBalance(t, acc, "direct"); got != 0 {
+		t.Errorf("balance = %d, want 0 — a forged notification credited chips", got)
+	}
+
+	// A payment we never made: the confirming read 404s, so there is nothing to credit.
+	if code := postYooKassaNotify(t, srv, ykSenderIP, yookassa.EventPaymentSucceeded, "pay-invented", orderID.String()); code != http.StatusOK {
+		t.Fatalf("notify for an unknown payment = %d, want 200", code)
+	}
+	if got := readBalance(t, acc, "direct"); got != 0 {
+		t.Errorf("balance = %d, want 0 — an invented payment credited chips", got)
+	}
+}
+
+// TestYooKassaNotifyRejectsForeignSenders checks the sender allowlist: an address outside YooKassa's
+// published ranges is refused before any provider call, so a forger cannot make us fan out requests.
+func TestYooKassaNotifyRejectsForeignSenders(t *testing.T) {
+	f, shop := newFakeYooKassa(t)
+	srv, pay := yookassaServer(t, shop)
+	acc := provisionAccount(t)
+	orderID, paymentID := seedYooKassaOrder(t, f, pay, acc)
+
+	if code := postYooKassaNotify(t, srv, "8.8.8.8", yookassa.EventPaymentSucceeded, paymentID, orderID.String()); code != http.StatusForbidden {
+		t.Fatalf("notify from a foreign address = %d, want 403", code)
+	}
+	if got := readBalance(t, acc, "direct"); got != 0 {
+		t.Errorf("balance = %d, want 0 — a foreign sender credited chips", got)
+	}
+}
+
+// TestYooKassaNotifyRejectsLiveOnTestShop is the guard that keeps play money out of a live ledger and
+// real money out of a test one: a payment whose test flag disagrees with the shop's is not credited.
+func TestYooKassaNotifyRejectsLiveOnTestShop(t *testing.T) {
+	f, shop := newFakeYooKassa(t)
+	srv, pay := yookassaServer(t, shop) // the shop is a test shop
+	acc := provisionAccount(t)
+	orderID, paymentID := seedYooKassaOrder(t, f, pay, acc)
+
+	f.setPayment(paymentID, func(p *yookassa.Payment) { p.Test = false }) // a live payment
+	if code := postYooKassaNotify(t, srv, ykSenderIP, yookassa.EventPaymentSucceeded, paymentID, orderID.String()); code != http.StatusOK {
+		t.Fatalf("notify = %d, want 200", code)
+	}
+	if got := readBalance(t, acc, "direct"); got != 0 {
+		t.Errorf("balance = %d, want 0 — a live payment credited against test credentials", got)
+	}
+}
+
+// TestYooKassaCanceledRecordsFailure checks an active decline records a failed payment event and
+// credits nothing, so the customer learns the attempt did not go through.
+func TestYooKassaCanceledRecordsFailure(t *testing.T) {
+	f, shop := newFakeYooKassa(t)
+	srv, pay := yookassaServer(t, shop)
+	acc := provisionAccount(t)
+	orderID, paymentID := seedYooKassaOrder(t, f, pay, acc)
+
+	f.setPayment(paymentID, func(p *yookassa.Payment) {
+		p.Status = yookassa.StatusCanceled
+		p.Paid = false
+		p.CancellationDetails = &yookassa.Cancellation{Party: "payment_network", Reason: "insufficient_funds"}
+	})
+	if code := postYooKassaNotify(t, srv, ykSenderIP, yookassa.EventPaymentCanceled, paymentID, orderID.String()); code != http.StatusOK {
+		t.Fatalf("notify = %d, want 200", code)
+	}
+	if got := readBalance(t, acc, "direct"); got != 0 {
+		t.Errorf("balance = %d, want 0 — a canceled payment credited chips", got)
+	}
+	if orderStatus(t, orderID) != "pending" {
+		t.Errorf("order status = %s, want pending (a decline does not settle the order)", orderStatus(t, orderID))
+	}
+	evs, err := pay.UndispatchedEvents(context.Background(), 50)
+	if err != nil {
+		t.Fatalf("read events: %v", err)
+	}
+	found := false
+	for _, e := range evs {
+		if e.AccountID == acc && e.Type == "failed" {
+			found = true
+		}
+	}
+	if !found {
+		t.Error("no failed payment event recorded for a declined payment")
+	}
+}
+
+// TestYooKassaReconcileCreditsLostNotification is the safety net: when no notification ever arrives,
+// the expiry-time check asks the provider and credits an order that was in fact paid.
+func TestYooKassaReconcileCreditsLostNotification(t *testing.T) {
+	f, shop := newFakeYooKassa(t)
+	srv, pay := yookassaServer(t, shop)
+	acc := provisionAccount(t)
+	orderID, _ := seedYooKassaOrder(t, f, pay, acc)
+
+	// Age the order past its lifetime without any notification having been delivered.
+	if _, err := testDB.ExecContext(context.Background(),
+		`UPDATE payments.orders SET created_at = now() - interval '2 days' WHERE order_id=$1`, orderID); err != nil {
+		t.Fatalf("age order: %v", err)
+	}
+	if n := srv.ReconcileYooKassaOrders(context.Background()); n != 1 {
+		t.Fatalf("reconciled %d orders, want 1", n)
+	}
+	if got := readBalance(t, acc, "direct"); got != 100 {
+		t.Errorf("balance = %d, want 100 — the safety net did not credit a paid order", got)
+	}
+	if orderStatus(t, orderID) != "paid" {
+		t.Errorf("order status = %s, want paid", orderStatus(t, orderID))
+	}
+	// A second sweep finds nothing left to do — the order is no longer pending.
+	if n := srv.ReconcileYooKassaOrders(context.Background()); n != 0 {
+		t.Errorf("second sweep credited %d orders, want 0", n)
+	}
+}
+
+// TestYooKassaReconcileLeavesUnpaidOrders checks the sweep does not invent a credit for an order the
+// customer abandoned.
+func TestYooKassaReconcileLeavesUnpaidOrders(t *testing.T) {
+	f, shop := newFakeYooKassa(t)
+	srv, pay := yookassaServer(t, shop)
+	acc := provisionAccount(t)
+	orderID, paymentID := seedYooKassaOrder(t, f, pay, acc)
+	f.setPayment(paymentID, func(p *yookassa.Payment) { p.Status = yookassa.StatusCanceled; p.Paid = false })
+
+	if _, err := testDB.ExecContext(context.Background(),
+		`UPDATE payments.orders SET created_at = now() - interval '2 days' WHERE order_id=$1`, orderID); err != nil {
+		t.Fatalf("age order: %v", err)
+	}
+	if n := srv.ReconcileYooKassaOrders(context.Background()); n != 0 {
+		t.Errorf("reconciled %d orders, want 0 (the payment was never completed)", n)
+	}
+	if got := readBalance(t, acc, "direct"); got != 0 {
+		t.Errorf("balance = %d, want 0", got)
+	}
+}
+
+// TestYooKassaConsoleRefundMovesMoneyThenRecords drives the operator refund end to end: the provider
+// refund is requested first and the ledger records the provider's own refund id.
+func TestYooKassaConsoleRefundMovesMoneyThenRecords(t *testing.T) {
+	f, shop := newFakeYooKassa(t)
+	srv, pay := yookassaServer(t, shop)
+	acc := provisionAccount(t)
+	orderID, paymentID := seedYooKassaOrder(t, f, pay, acc)
+	if code := postYooKassaNotify(t, srv, ykSenderIP, yookassa.EventPaymentSucceeded, paymentID, orderID.String()); code != http.StatusOK {
+		t.Fatalf("notify = %d, want 200", code)
+	}
+
+	h := srv.Handler()
+	base := "http://admin.test/_gm/users/" + acc.String()
+	code, body := consoleDo(h, http.MethodPost, base+"/refund", "order_id="+orderID.String(), "http://admin.test")
+	if code != http.StatusOK || !strings.Contains(body, "revoked 100 chips") {
+		t.Fatalf("refund = %d, body has 'revoked 100 chips' = %v", code, strings.Contains(body, "revoked 100 chips"))
+	}
+	if f.refundCalls != 1 {
+		t.Errorf("provider refunds requested = %d, want 1", f.refundCalls)
+	}
+	if got := readBalance(t, acc, "direct"); got != 0 {
+		t.Errorf("balance after refund = %d, want 0", got)
+	}
+	// The ledger records the provider's own refund id, which is what keeps it reconcilable against
+	// YooKassa's records — and is distinct from the payment id, so both rows coexist.
+	var provider, refundID string
+	if err := testDB.QueryRowContext(context.Background(),
+		`SELECT provider, provider_payment_id FROM payments.ledger WHERE account_id=$1 AND kind='refund'`,
+		acc).Scan(&provider, &refundID); err != nil {
+		t.Fatalf("read refund ledger row: %v", err)
+	}
+	if provider != "yookassa" || refundID != "refund-1" {
+		t.Errorf("refund ledger row = (%s, %s), want (yookassa, refund-1)", provider, refundID)
+	}
+}
+
+// TestYooKassaRefundRecordsNothingWhenTheProviderFails is the invariant that keeps the ledger honest:
+// if the money did not move, nothing is written.
+func TestYooKassaRefundRecordsNothingWhenTheProviderFails(t *testing.T) {
+	f, shop := newFakeYooKassa(t)
+	srv, pay := yookassaServer(t, shop)
+	acc := provisionAccount(t)
+	orderID, paymentID := seedYooKassaOrder(t, f, pay, acc)
+	if code := postYooKassaNotify(t, srv, ykSenderIP, yookassa.EventPaymentSucceeded, paymentID, orderID.String()); code != http.StatusOK {
+		t.Fatalf("notify = %d, want 200", code)
+	}
+
+	f.refundFails = true
+	h := srv.Handler()
+	base := "http://admin.test/_gm/users/" + acc.String()
+	_, body := consoleDo(h, http.MethodPost, base+"/refund", "order_id="+orderID.String(), "http://admin.test")
+	if !strings.Contains(body, "nothing was recorded") {
+		t.Errorf("refund failure message = %q, want it to say nothing was recorded", body)
+	}
+	if got := readBalance(t, acc, "direct"); got != 100 {
+		t.Errorf("balance = %d, want 100 — chips were revoked without the money moving", got)
+	}
+	if ledgerRows(t, acc, "refund") != 0 {
+		t.Error("a refund ledger row was written although the provider did not refund")
+	}
+}
+
+// TestYooKassaOrderMintsAPaymentWithAReceipt drives the purchase path over HTTP: the order endpoint
+// calls the provider, threads the order id through, sends the fiscal receipt to the buyer's confirmed
+// address, and hands the client the hosted payment page.
+func TestYooKassaOrderMintsAPaymentWithAReceipt(t *testing.T) {
+	f, shop := newFakeYooKassa(t)
+	srv, _ := yookassaServer(t, shop)
+	acc := provisionAccount(t)
+	const email = "buyer@example.test"
+	if _, err := testDB.ExecContext(context.Background(),
+		`INSERT INTO backend.identities (identity_id, account_id, kind, external_id, confirmed) VALUES ($1,$2,'email',$3,true)`,
+		uuid.New(), acc, email); err != nil {
+		t.Fatalf("seed email identity: %v", err)
+	}
+	prod := seedPackProduct(t, 100, methodPrice{method: "direct", currency: "RUB", amount: 14900})
+
+	req := httptest.NewRequest(http.MethodPost, "/api/v1/user/wallet/order",
+		strings.NewReader(fmt.Sprintf(`{"product_id":%q}`, prod)))
+	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("X-User-ID", acc.String())
+	req.Header.Set("X-Platform", "direct/web")
+	rec := httptest.NewRecorder()
+	srv.Handler().ServeHTTP(rec, req)
+	if rec.Code != http.StatusOK {
+		t.Fatalf("order = %d, want 200: %s", rec.Code, rec.Body.String())
+	}
+	var out struct {
+		OrderID     string `json:"order_id"`
+		RedirectURL string `json:"redirect_url"`
+		Rail        string `json:"rail"`
+	}
+	if err := json.Unmarshal(rec.Body.Bytes(), &out); err != nil {
+		t.Fatalf("decode order response: %v", err)
+	}
+	if out.Rail != "yookassa" || !strings.HasPrefix(out.RedirectURL, "https://yoomoney.test/pay/") {
+		t.Errorf("order response = %+v, want the yookassa rail and its hosted payment page", out)
+	}
+	// The order id is both the idempotency key (so a retried create cannot mint a second payment)
+	// and the metadata that later resolves a notification to this order.
+	if f.createdIdempotenceKey != out.OrderID {
+		t.Errorf("Idempotence-Key = %q, want the order id %q", f.createdIdempotenceKey, out.OrderID)
+	}
+	customer, _ := f.lastReceipt["customer"].(map[string]any)
+	if customer["email"] != email {
+		t.Errorf("receipt customer = %v, want the confirmed email %q", customer, email)
+	}
+	items, _ := f.lastReceipt["items"].([]any)
+	if len(items) != 1 {
+		t.Fatalf("receipt items = %d, want 1", len(items))
+	}
+	item, _ := items[0].(map[string]any)
+	if item["vat_code"] != float64(yookassa.VatCodeNone) || item["payment_subject"] != yookassa.PaymentSubjectService {
+		t.Errorf("receipt fiscal attributes = %v", item)
+	}
+	// The payment id is recorded on the order, which is what the safety net and a refund need.
+	orderID, err := uuid.Parse(out.OrderID)
+	if err != nil {
+		t.Fatalf("parse order id: %v", err)
+	}
+	var paymentID string
+	if err := testDB.QueryRowContext(context.Background(),
+		`SELECT provider_payment_id FROM payments.orders WHERE order_id=$1`, orderID).Scan(&paymentID); err != nil {
+		t.Fatalf("read order payment id: %v", err)
+	}
+	if paymentID != "pay-"+out.OrderID {
+		t.Errorf("order provider_payment_id = %q, want the minted payment id", paymentID)
+	}
+}
+
+// TestYooKassaOrderRequiresAnEmailAnchor keeps D36 in force on the new rail: without a confirmed
+// address there is no recovery anchor and nowhere to deliver the fiscal receipt, so no payment is
+// minted at all.
+func TestYooKassaOrderRequiresAnEmailAnchor(t *testing.T) {
+	_, shop := newFakeYooKassa(t)
+	srv, _ := yookassaServer(t, shop)
+	acc := provisionAccount(t) // a telegram identity only — no confirmed email
+	prod := seedPackProduct(t, 100, methodPrice{method: "direct", currency: "RUB", amount: 14900})
+
+	req := httptest.NewRequest(http.MethodPost, "/api/v1/user/wallet/order",
+		strings.NewReader(fmt.Sprintf(`{"product_id":%q}`, prod)))
+	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("X-User-ID", acc.String())
+	req.Header.Set("X-Platform", "direct/web")
+	rec := httptest.NewRecorder()
+	srv.Handler().ServeHTTP(rec, req)
+	if rec.Code != http.StatusForbidden || !strings.Contains(rec.Body.String(), "email_required") {
+		t.Fatalf("order = %d (%s), want 403 email_required", rec.Code, rec.Body.String())
+	}
+}

backend/internal/payments/refund_admin.go

@@ -11,11 +11,24 @@ import (
 // one manual full refund per order.
 const providerAdmin = "admin"
 
-// RefundOrderFull refunds a paid order in full at the operator's request: it revokes the funded
-// chips best-effort (floored at 0, never negative — D27), records a refund ledger row, and is
-// idempotent (a second call reports AlreadyRefunded). The operator performs the actual money refund
-// on the rail (Robokassa cabinet / VK support / Telegram refundStarPayment); this records it.
+// RefundOrderFull refunds a paid order in full at the operator's request, recording the reversal
+// only. It is for the rails that have no refund API of our own to call: the operator performs the
+// actual money refund there by hand (VK support, Telegram refundStarPayment, the Robokassa cabinet),
+// and this records it under the operator's own idempotency key.
 func (s *Service) RefundOrderFull(ctx context.Context, orderID uuid.UUID) (RefundOutcome, error) {
+	return s.RefundOrderFullAs(ctx, orderID, providerAdmin, orderID.String())
+}
+
+// RefundOrderFullAs refunds a paid order in full and records it under the given provider and refund
+// id: it revokes the funded chips best-effort (floored at 0, never negative — D27), appends a refund
+// ledger row and is idempotent on (provider, providerRefundID), so a second call reports
+// AlreadyRefunded. Callers whose rail moved the money through an API pass that rail's own refund id,
+// which keeps the ledger reconcilable against the provider's records; the refund id is distinct from
+// the fund's payment id, so the two rows coexist under the same partial-unique index.
+//
+// The provider-side money movement must already have succeeded when this is called — the ledger must
+// never claim a refund that did not happen.
+func (s *Service) RefundOrderFullAs(ctx context.Context, orderID uuid.UUID, provider, providerRefundID string) (RefundOutcome, error) {
 	o, err := s.store.orderByID(ctx, orderID)
 	if err != nil {
 		return RefundOutcome{}, err
@@ -24,7 +37,7 @@ func (s *Service) RefundOrderFull(ctx context.Context, orderID uuid.UUID) (Refun
 	if err != nil {
 		return RefundOutcome{}, err
 	}
-	return s.store.refund(ctx, orderID, providerAdmin, orderID.String(), refunded, s.clock())
+	return s.store.refund(ctx, orderID, provider, providerRefundID, refunded, s.clock())
 }
 
 // LedgerExportRow is one append-only ledger row for the tax / reconciliation export, carrying the

backend/internal/payments/service_intake.go

@@ -64,6 +64,83 @@ func directShop(cxt Context) string {
 	return ""
 }
 
+// AttachProviderPayment records the provider's own payment identifier on a pending order, right
+// after the provider mints it and before the customer has paid. Two later paths depend on it: the
+// reconcile sweep, which asks the provider what became of an order no callback ever confirmed, and a
+// refund, which must address the original payment. It does not credit anything and does not change
+// the order status.
+func (s *Service) AttachProviderPayment(ctx context.Context, orderID uuid.UUID, provider, providerPaymentID string) error {
+	return s.store.attachProviderPayment(ctx, orderID, provider, providerPaymentID, s.clock())
+}
+
+// OrderRef identifies a stored order to a provider: which rail settles it, that rail's own payment
+// id, the merchant shop channel it was issued through, and the amount and account it belongs to. It
+// is what the reconcile sweep and the refund path need without giving them the whole order.
+type OrderRef struct {
+	OrderID   uuid.UUID
+	AccountID uuid.UUID
+	Provider  string
+	PaymentID string
+	Shop      string
+	Amount    Money
+	Status    string
+}
+
+// orderRef projects a stored order onto an OrderRef.
+func orderRef(o orderRow) (OrderRef, error) {
+	amount, err := MoneyFromMinor(o.expectedAmount, Currency(o.currency))
+	if err != nil {
+		return OrderRef{}, err
+	}
+	return OrderRef{
+		OrderID:   o.orderID,
+		AccountID: o.accountID,
+		Provider:  o.provider,
+		PaymentID: o.paymentID,
+		Shop:      o.shop,
+		Amount:    amount,
+		Status:    o.status,
+	}, nil
+}
+
+// OrderProviderRef reads how an order reaches its provider — the rail, that rail's payment id and
+// the shop it was issued through. The refund path uses it to call the right merchant account.
+func (s *Service) OrderProviderRef(ctx context.Context, orderID uuid.UUID) (OrderRef, error) {
+	o, err := s.store.orderByID(ctx, orderID)
+	if err != nil {
+		return OrderRef{}, err
+	}
+	return orderRef(o)
+}
+
+// reconcileBatch bounds one reconcile sweep, so a backlog cannot turn a periodic tick into a long
+// run of provider calls.
+const reconcileBatch = 50
+
+// PendingForReconcile returns the pending orders that have reached their expiry age while carrying a
+// provider payment id — the ones where the money may well have moved but no callback ever told us.
+// The caller asks the provider for each one's real outcome before ExpireOrders writes them off.
+// Orders that never reached a payment are not returned: there is nothing to ask about.
+func (s *Service) PendingForReconcile(ctx context.Context) ([]OrderRef, error) {
+	ttl, err := s.store.orderTTL(ctx)
+	if err != nil {
+		return nil, err
+	}
+	rows, err := s.store.pendingForReconcile(ctx, ttl, s.clock(), reconcileBatch)
+	if err != nil {
+		return nil, err
+	}
+	out := make([]OrderRef, 0, len(rows))
+	for _, r := range rows {
+		ref, err := orderRef(r)
+		if err != nil {
+			return nil, err
+		}
+		out = append(out, ref)
+	}
+	return out, nil
+}
+
 // OrderItem returns a pending order's human title and the amount it charges, in the order's own
 // currency — the details a provider's item-lookup phase needs (VK's get_item). It reads the order
 // and the pack title, honouring the pack even if it was later deactivated (mirrors Fund).

backend/internal/payments/store_intake.go

@@ -182,6 +182,9 @@ type orderRow struct {
 	currency       string
 	origin         string
 	status         string
+	provider       string
+	paymentID      string
+	shop           string
 }
 
 // orderByID reads an order, or ErrOrderNotFound.
@@ -198,6 +201,12 @@ func (s *Store) orderByID(ctx context.Context, orderID uuid.UUID) (orderRow, err
 	if err != nil {
 		return orderRow{}, fmt.Errorf("payments: load order %s: %w", orderID, err)
 	}
+	return newOrderRow(o), nil
+}
+
+// newOrderRow projects a stored order onto the intake's view of it, flattening the nullable provider
+// columns to their empty strings.
+func newOrderRow(o model.Orders) orderRow {
 	return orderRow{
 		orderID:        o.OrderID,
 		accountID:      o.AccountID,
@@ -206,7 +215,60 @@ func (s *Store) orderByID(ctx context.Context, orderID uuid.UUID) (orderRow, err
 		currency:       o.Currency,
 		origin:         o.Origin,
 		status:         o.Status,
-	}, nil
+		provider:       derefString(o.Provider),
+		paymentID:      derefString(o.ProviderPaymentID),
+		shop:           o.Shop,
+	}
+}
+
+// derefString reads a nullable text column as a plain string, treating NULL as empty.
+func derefString(p *string) string {
+	if p == nil {
+		return ""
+	}
+	return *p
+}
+
+// attachProviderPayment records the provider's own payment id on a pending order, as soon as the
+// provider mints it. It is what later lets an unattended order be re-checked against the provider
+// and a refund address the right payment; fund overwrites it with the same value when the callback
+// lands. It never changes the order status.
+func (s *Store) attachProviderPayment(ctx context.Context, orderID uuid.UUID, provider, providerPaymentID string, now time.Time) error {
+	_, err := table.Orders.
+		UPDATE(table.Orders.Provider, table.Orders.ProviderPaymentID, table.Orders.UpdatedAt).
+		SET(postgres.String(provider), postgres.String(providerPaymentID), postgres.TimestampzT(now)).
+		WHERE(table.Orders.OrderID.EQ(postgres.UUID(orderID))).
+		ExecContext(ctx, s.db)
+	if err != nil {
+		return fmt.Errorf("payments: attach provider payment to order %s: %w", orderID, err)
+	}
+	return nil
+}
+
+// pendingForReconcile reads the pending orders that have reached their expiry age and carry a
+// provider payment id — the ones whose real outcome is still unknown to us because no callback ever
+// arrived. The caller asks the provider what happened before the order is written off as expired.
+// Orders with no provider payment id are skipped: the customer never got as far as a payment.
+func (s *Store) pendingForReconcile(ctx context.Context, ttlSeconds int, now time.Time, limit int) ([]orderRow, error) {
+	cutoff := now.Add(-time.Duration(ttlSeconds) * time.Second)
+	var rows []model.Orders
+	err := postgres.SELECT(table.Orders.AllColumns).
+		FROM(table.Orders).
+		WHERE(table.Orders.Status.EQ(postgres.String("pending")).
+			AND(table.Orders.CreatedAt.LT(postgres.TimestampzT(cutoff))).
+			AND(table.Orders.ProviderPaymentID.IS_NOT_NULL()).
+			AND(table.Orders.ProviderPaymentID.NOT_EQ(postgres.String("")))).
+		ORDER_BY(table.Orders.CreatedAt.ASC()).
+		LIMIT(int64(limit)).
+		QueryContext(ctx, s.db, &rows)
+	if err != nil && !errors.Is(err, qrm.ErrNoRows) {
+		return nil, fmt.Errorf("payments: load orders for reconcile: %w", err)
+	}
+	out := make([]orderRow, 0, len(rows))
+	for _, r := range rows {
+		out = append(out, newOrderRow(r))
+	}
+	return out, nil
 }
 
 // FundOutcome reports the result of an intake credit: whose balance, which segment and how many

backend/internal/robokassa/README.md

@@ -0,0 +1,85 @@
+# Robokassa — the retired direct rail
+
+Robokassa used to settle the **`direct`** (RUB) rail. It was replaced by
+[YooKassa](../yookassa) and is now **dormant**: the code, its tests and its wiring are all still
+here, but **no deployment sets its credentials**, so `Shops.Configured()` is false, the Result
+callback route is never registered, and the direct rail resolves to YooKassa.
+
+The code is kept because the merchant relationship could come back. This file records the operational
+knowledge that used to live in `deploy/` and `.gitea/workflows/` and was removed from there so the
+live configuration stays free of dead variables.
+
+## How the rail is chosen
+
+`handleWalletOrder` (`backend/internal/server/handlers_intake.go`) resolves the direct rail in this
+order:
+
+1. a configured YooKassa shop for the platform channel → YooKassa;
+2. otherwise a configured Robokassa shop → **this rail**;
+3. otherwise `501 rail_unavailable`.
+
+So reviving Robokassa is a **credentials change, not a code change**: restore the environment block
+below and the rail comes back on the next deploy. If both providers are configured, YooKassa wins.
+
+## Environment variables (retired)
+
+The backend still reads all of these. They were removed from `deploy/docker-compose.yml`,
+`deploy/.env.example`, `deploy/write-prod-env.sh`, `deploy/README.md` and the three workflows.
+
+| Backend variable (inside the container) | Meaning |
+| --- | --- |
+| `BACKEND_ROBOKASSA_MERCHANT_LOGIN` | Shop login. Empty ⇒ the shop is dropped. Legacy single-shop form: it seeds the **web** channel. |
+| `BACKEND_ROBOKASSA_PASSWORD1` | Pass phrase #1 — signs the outgoing payment request. |
+| `BACKEND_ROBOKASSA_PASSWORD2` | Pass phrase #2 — signs and so verifies the incoming Result callback. |
+| `BACKEND_ROBOKASSA_TEST` | `1` adds `IsTest=1`, so the shop simulates payments against its **test** pass phrases and no money moves. Empty/`0` is live. |
+| `BACKEND_ROBOKASSA_WEB_{MERCHANT_LOGIN,PASSWORD1,PASSWORD2,TEST}` | The per-channel **web** shop; overrides the legacy set above. |
+| `BACKEND_ROBOKASSA_ANDROID_{MERCHANT_LOGIN,PASSWORD1,PASSWORD2,TEST}` | The per-channel **android** (RuStore) shop (D42). |
+
+Password3 (Robokassa's JWT-invoice API) was never used.
+
+The three-step naming this repo uses was: a Gitea secret/variable `PROD_BACKEND_ROBOKASSA_PASSWORD1`
+→ mapped by the workflow to `ROBOKASSA_PASSWORD1` → mapped by compose to
+`BACKEND_ROBOKASSA_PASSWORD1` inside the container.
+
+| Contour | Gitea entries that fed the rail |
+| --- | --- |
+| test | secrets `TEST_BACKEND_ROBOKASSA_{MERCHANT_LOGIN,PASSWORD1,PASSWORD2}`; `ROBOKASSA_TEST` was hard-coded to `"1"` in `ci.yaml` so the contour could never take real money whatever the shop's own mode. |
+| prod | secrets `PROD_BACKEND_ROBOKASSA_{MERCHANT_LOGIN,PASSWORD1,PASSWORD2}`; **variable** `PROD_BACKEND_ROBOKASSA_TEST`, deliberately a variable so go-live was a flag flip rather than a secret rotation. Mirrored in `prod-rollback.yaml` so a rollback did not dark the rail. |
+
+**Known gap, if the rail is ever revived:** the per-channel `…_WEB_*` / `…_ANDROID_*` variables
+existed in compose and in `config.go` but were **never** carried by any workflow or by
+`write-prod-env.sh` — only the four legacy variables reached prod. A revival that wants the
+multi-shop split must add them to the deploy plumbing too.
+
+## Cabinet configuration
+
+Set in the Robokassa ЛКК, per shop:
+
+- **Result URL** — `https://<host>/pay/robokassa/result/<channel>` (`…/web`, `…/android`). The bare
+  `…/pay/robokassa/result` is the legacy path and is verified as the **web** shop. Method: POST.
+  Each shop's callback is verified only by its own Password2 (`Shops.Verifier` does not fall back).
+- **Success URL** — `https://<host>/pay/robokassa/success`.
+- **Fail URL** — `https://<host>/pay/robokassa/fail`.
+- **Signature algorithm** — SHA-256 (the code hard-codes it; a shop set to MD5 will not verify).
+- **54-ФЗ** — fiscalization was cabinet-side through Robokassa's cloud cash register (kassa + ОФД +
+  СНО configured by the owner), so no receipt data was ever sent from code. YooKassa does **not**
+  work this way: it registers a receipt only if the request carries one.
+
+The gateway routes (`gateway/internal/connectsrv/server.go`) are still registered, so the cabinet
+URLs above stay reachable; only the backend has no shop to verify against.
+
+## Protocol notes
+
+- The order id is a UUID and Robokassa's `InvId` is numeric, so the order rides the custom-parameter
+  channel as **`Shp_order`** and `InvId` is always sent as `0`. Idempotency at the credit site is
+  therefore keyed on the order id, not on a provider payment id.
+- Outgoing signature base: `MerchantLogin:OutSum:InvId:Password1[:Shp_key=value…sorted]`.
+- Incoming (Result) signature base: `OutSum:InvId:Password2[:Shp_key=value…sorted]`, compared
+  case-insensitively.
+- The Result callback must be answered with the body `OK<InvId>`, which the gateway echoes verbatim.
+
+## What is *not* reversible by configuration
+
+Ledger rows written while this rail was live carry `provider = 'robokassa'`. That literal is
+load-bearing for the `(provider, provider_payment_id)` idempotency index and must never be renamed or
+reused for another provider.

backend/internal/robokassa/robokassa.go

@@ -3,6 +3,12 @@
 // an order. It is pure provider glue — no database, no payments-domain coupling — so the payments
 // domain stays provider-agnostic and this layer is unit-testable in isolation.
 //
+// This rail is RETIRED: YooKassa settles the direct rail now, and no deployment sets these
+// credentials, so the shop set is empty and the rail is dormant. It stays wired as the fallback the
+// direct rail resolves to when YooKassa has no shop, which makes reviving it a credentials change
+// rather than a code change. README.md in this directory records the retired environment variables,
+// the cabinet configuration and how to bring the rail back.
+//
 // The order is threaded through Robokassa's custom-parameter channel as Shp_order=<order id> (echoed
 // back in the callback and bound into the signature), not the numeric InvId, because an order id is
 // a uuid; InvId is sent as 0. Idempotency is therefore keyed on the order id at the credit site.

backend/internal/server/handlers.go

@@ -79,16 +79,20 @@ func (s *Server) registerRoutes() {
 		s.internal.GET("/offer/pricing", s.handleOfferPricing)
 	}
 	if s.payments != nil {
-		// The money order endpoint dispatches by rail (direct → Robokassa, vk → VK); an
+		// The money order endpoint dispatches by rail (direct → YooKassa, vk → VK); an
 		// unsupported or unconfigured rail returns 501 from the handler. The provider callbacks are
-		// gateway-only (the single writer): the VK payment callback (both phases handled here), and
-		// the Robokassa Result callback when a merchant is configured.
+		// gateway-only (the single writer): the VK payment callback (both phases handled here), the
+		// YooKassa notification, and the retired Robokassa Result callback if a merchant is ever
+		// configured again.
 		u.POST("/wallet/order", s.handleWalletOrder)
 		s.internal.POST("/payments/vk/callback", s.handleVKCallback)
 		// The Telegram Stars rail: the bot forwards a pre_checkout validation and a completed
 		// payment over the reverse bot-link; the gateway proxies both onto these gateway-only routes.
 		s.internal.POST("/payments/telegram/precheckout", s.handleTelegramPreCheckout)
 		s.internal.POST("/payments/telegram/payment", s.handleTelegramPayment)
+		if s.yookassa.Configured() {
+			s.internal.POST("/payments/yookassa/notify", s.handleYooKassaNotify)
+		}
 		if s.robokassa.Configured() {
 			s.internal.POST("/payments/robokassa/result", s.handleRobokassaResult)
 		}

backend/internal/server/handlers_admin_refund.go

@@ -1,6 +1,7 @@
 package server
 
 import (
+	"context"
 	"encoding/csv"
 	"fmt"
 	"strconv"
@@ -9,11 +10,17 @@ import (
 
 	"github.com/gin-gonic/gin"
 	"github.com/google/uuid"
+	"go.uber.org/zap"
+
+	"scrabble/backend/internal/payments"
 )
 
-// consoleRefund refunds a paid order in full at the operator's request. The operator performs the
-// actual money refund on the rail (Robokassa cabinet / VK support / Telegram refundStarPayment);
-// this records it — a refund ledger row and a floor-0 chip revoke (never negative, D27). Idempotent.
+// consoleRefund refunds a paid order in full at the operator's request: it records the reversal — a
+// refund ledger row and a floor-0 chip revoke (never negative, D27) — and, on the direct rail, moves
+// the money back through the provider's refund API first, so one click does the whole job and the
+// ledger cannot claim a refund the provider never made. The rails with no refund API of ours (VK
+// support, Telegram refundStarPayment, the Robokassa cabinet) still need the operator to move the
+// money by hand; this records that. Idempotent either way.
 func (s *Server) consoleRefund(c *gin.Context) {
 	id, ok := s.consoleUUID(c, "/_gm/users")
 	if !ok {
@@ -29,7 +36,13 @@ func (s *Server) consoleRefund(c *gin.Context) {
 		s.renderConsoleMessage(c, "Refund failed", "no order to refund", back)
 		return
 	}
-	out, err := s.payments.RefundOrderFull(c.Request.Context(), orderID)
+	ctx := c.Request.Context()
+	ref, err := s.payments.OrderProviderRef(ctx, orderID)
+	if err != nil {
+		s.renderConsoleMessage(c, "Refund failed", err.Error(), back)
+		return
+	}
+	out, err := s.refundOrder(ctx, ref)
 	if err != nil {
 		s.renderConsoleMessage(c, "Refund failed", err.Error(), back)
 		return
@@ -46,6 +59,25 @@ func (s *Server) consoleRefund(c *gin.Context) {
 	s.renderConsoleMessage(c, "Refunded", msg, back)
 }
 
+// refundOrder reverses a paid order, moving the money back through the rail's own refund API when
+// there is one. The provider call comes first and a failure aborts with nothing recorded: the ledger
+// must never claim a refund that did not happen. The reversal is then recorded under the provider's
+// own refund id, which keeps the ledger reconcilable against the provider's records.
+//
+// A rail with no refund API of ours records under the operator's key instead, and the operator moves
+// the money by hand (VK support, Telegram refundStarPayment, the Robokassa cabinet).
+func (s *Server) refundOrder(ctx context.Context, ref payments.OrderRef) (payments.RefundOutcome, error) {
+	if ref.Provider != providerYooKassa {
+		return s.payments.RefundOrderFull(ctx, ref.OrderID)
+	}
+	refundID, err := s.refundYooKassa(ctx, ref)
+	if err != nil {
+		s.log.Error("yookassa refund failed", zap.String("order", ref.OrderID.String()), zap.Error(err))
+		return payments.RefundOutcome{}, fmt.Errorf("the provider did not refund the payment, nothing was recorded: %w", err)
+	}
+	return s.payments.RefundOrderFullAs(ctx, ref.OrderID, providerYooKassa, refundID)
+}
+
 // consoleLedgerExport streams the entire append-only ledger as a CSV attachment for tax reporting
 // and rail reconciliation. The snapshot column carries the raw purchase/refund JSON.
 func (s *Server) consoleLedgerExport(c *gin.Context) {

backend/internal/server/handlers_intake.go

@@ -15,20 +15,28 @@ import (
 	"scrabble/backend/internal/robokassa"
 )
 
-// Ledger/order provider tags per rail.
+// Ledger/order provider tags per rail. providerRobokassa is retired but never renamed or reused:
+// historical ledger rows carry it, and it is load-bearing for the (provider, provider_payment_id)
+// idempotency index.
 const (
-	providerRobokassa = "robokassa" // the direct (RUB) rail
+	providerYooKassa  = "yookassa"  // the direct (RUB) rail
+	providerRobokassa = "robokassa" // the retired direct (RUB) rail
 	providerVK        = "vk"        // the VK Votes rail
 	providerTelegram  = "telegram"  // the Telegram Stars (XTR) rail
 )
 
+// yookassaReturnPath is where YooKassa returns the customer's browser after the hosted payment page.
+// The credit never rides this redirect — it rides the server notification — so the page only closes
+// the payment window and drops the customer back into the live app.
+const yookassaReturnPath = "/pay/yookassa/return"
+
 // walletOrderRequest is the POST body of a chip-pack purchase: the pack to fund.
 type walletOrderRequest struct {
 	ProductID string `json:"product_id"`
 }
 
 // walletOrderResponse returns the created order id and the rail's launch details. RedirectURL is
-// the provider's hosted-payment URL for the direct rail (empty for VK/Telegram, which settle
+// the provider's hosted-payment page for the direct rail (empty for VK/Telegram, which settle
 // in-app). Rail names the settling rail so the gateway knows how to launch it; for the Telegram
 // Stars rail the gateway mints the invoice link from InvoiceTitle and InvoiceAmount (whole stars)
 // via the bot and returns it in RedirectURL.
@@ -41,7 +49,7 @@ type walletOrderResponse struct {
 }
 
 // handleWalletOrder opens a pending order to fund a chip pack and returns the rail's launch
-// details for the client: the Robokassa hosted-payment URL (direct), the order id for
+// details for the client: the provider's hosted-payment URL (direct), the order id for
 // VKWebAppShowOrderBox (VK), or the pack title and star amount the gateway mints into a Stars
 // invoice link (Telegram). It enforces the wallet gate and, on the direct rail, D36 (a purchase
 // requires a confirmed email anchor). No chips are credited here — only later, by the verified
@@ -84,13 +92,20 @@ func (s *Server) handleWalletOrder(c *gin.Context) {
 	}
 	switch cxt.Kind {
 	case payments.SourceDirect:
-		shop, ok := s.robokassa.Shop(cxt.Subtype)
-		if !ok {
+		// YooKassa settles the direct rail. Robokassa is retired and normally unconfigured, so it is
+		// only reached when YooKassa has no shop for this channel — which is what makes reviving the
+		// old rail a credentials change rather than a code change. The rail is resolved before any
+		// account-level gate, so an unconfigured rail still reads as unavailable rather than as
+		// something the customer could fix.
+		ykShop, onYooKassa := s.yookassa.Shop(cxt.Subtype)
+		rkShop, onRobokassa := s.robokassa.Shop(cxt.Subtype)
+		if !onYooKassa && !onRobokassa {
 			c.AbortWithStatusJSON(http.StatusNotImplemented, errorResponse{Error: errorBody{Code: "rail_unavailable", Message: "this payment method is not available"}})
 			return
 		}
-		// D36: a direct purchase requires a confirmed email anchor.
-		hasEmail, err := s.accounts.HasConfirmedEmail(ctx, uid)
+		// D36: a direct purchase requires a confirmed email anchor, which is also where the fiscal
+		// receipt is delivered.
+		email, hasEmail, err := s.accounts.ConfirmedEmail(ctx, uid)
 		if err != nil {
 			s.abortErr(c, err)
 			return
@@ -99,6 +114,10 @@ func (s *Server) handleWalletOrder(c *gin.Context) {
 			c.AbortWithStatusJSON(http.StatusForbidden, errorResponse{Error: errorBody{Code: "email_required", Message: "confirm your email before making a purchase"}})
 			return
 		}
+		if onYooKassa {
+			s.orderYooKassa(c, uid, cxt, present, productID, ykShop, email)
+			return
+		}
 		res, err := s.payments.CreateOrder(ctx, uid, cxt, present, productID, providerRobokassa)
 		if err != nil {
 			s.abortErr(c, err)
@@ -106,7 +125,7 @@ func (s *Server) handleWalletOrder(c *gin.Context) {
 		}
 		c.JSON(http.StatusOK, walletOrderResponse{
 			OrderID:     res.OrderID.String(),
-			RedirectURL: shop.PaymentURL(res.OrderID, res.Amount.Major(), res.Title),
+			RedirectURL: rkShop.PaymentURL(res.OrderID, res.Amount.Major(), res.Title),
 			Rail:        providerRobokassa,
 		})
 	case payments.SourceVK:

backend/internal/server/handlers_yookassa.go

@@ -0,0 +1,355 @@
+package server
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"io"
+	"net/http"
+	"strings"
+
+	"github.com/gin-gonic/gin"
+	"github.com/google/uuid"
+	"go.uber.org/zap"
+
+	"scrabble/backend/internal/payments"
+	"scrabble/backend/internal/yookassa"
+)
+
+// maxNotifyBytes caps the notification body the backend will read. The gateway already forwards only
+// what it read from the provider; this is the backend's own ceiling on an untrusted body.
+const maxNotifyBytes = 1 << 20
+
+// orderYooKassa opens a pending order on the direct rail and mints the YooKassa payment the customer
+// is redirected to. shop is the merchant shop the caller resolved for this platform channel, and
+// email is the account's confirmed address (D36), which doubles as the delivery address of the fiscal
+// receipt this rail must send with every payment. No chips are credited here —
+// only later, by the verified notification (or the reconcile sweep).
+func (s *Server) orderYooKassa(c *gin.Context, uid uuid.UUID, cxt payments.Context, present []payments.Source, productID uuid.UUID, shop yookassa.Config, email string) {
+	ctx := c.Request.Context()
+	res, err := s.payments.CreateOrder(ctx, uid, cxt, present, productID, providerYooKassa)
+	if err != nil {
+		s.abortErr(c, err)
+		return
+	}
+	amount := yookassa.Amount{Value: res.Amount.Major(), Currency: string(res.Amount.Currency())}
+	payment, err := shop.CreatePayment(ctx, yookassa.PaymentRequest{
+		Amount:  amount,
+		Capture: true,
+		Confirmation: yookassa.Confirmation{
+			Type:      yookassa.ConfirmationRedirect,
+			ReturnURL: strings.TrimSuffix(s.publicURL, "/") + yookassaReturnPath,
+		},
+		Description: yookassa.TruncateDescription(res.Title),
+		Metadata:    map[string]string{yookassa.MetadataOrderID: res.OrderID.String()},
+		// «Чеки от ЮKassa»: the receipt is registered only if we send it, so a malformed one is an
+		// API error here rather than a silently missing fiscal document.
+		Receipt: yookassa.SingleItemReceipt(email, res.Title, amount, s.vatCode),
+	}, res.OrderID.String())
+	if err != nil {
+		// The order stays pending and unpaid; it expires on its own. The customer sees the generic
+		// error, and the log carries the provider's own description (which names the offending
+		// parameter when a receipt is at fault).
+		s.log.Error("yookassa create payment failed", zap.String("order", res.OrderID.String()), zap.Error(err))
+		c.AbortWithStatusJSON(http.StatusBadGateway, errorResponse{Error: errorBody{Code: "rail_unavailable", Message: "this payment method is not available right now"}})
+		return
+	}
+	if payment.Confirmation.ConfirmationURL == "" {
+		s.log.Error("yookassa payment has no confirmation url",
+			zap.String("order", res.OrderID.String()), zap.String("payment", payment.ID))
+		c.AbortWithStatusJSON(http.StatusBadGateway, errorResponse{Error: errorBody{Code: "rail_unavailable", Message: "this payment method is not available right now"}})
+		return
+	}
+	// Record the provider's payment id so the reconcile sweep and any refund can address it. A
+	// failure here is logged and tolerated: the credit path matches on the order id carried in the
+	// payment metadata, so the purchase still completes — only the safety net and refunds lose their
+	// handle on this one order.
+	if err := s.payments.AttachProviderPayment(ctx, res.OrderID, providerYooKassa, payment.ID); err != nil {
+		s.log.Error("yookassa attach payment id failed",
+			zap.String("order", res.OrderID.String()), zap.String("payment", payment.ID), zap.Error(err))
+	}
+	c.JSON(http.StatusOK, walletOrderResponse{
+		OrderID:     res.OrderID.String(),
+		RedirectURL: payment.Confirmation.ConfirmationURL,
+		Rail:        providerYooKassa,
+	})
+}
+
+// handleYooKassaNotify is the YooKassa webhook, reached only through the gateway (which checks the
+// sender address and forwards the raw JSON body on the internal, gateway-only route).
+//
+// YooKassa does not sign notifications, so the body is never evidence: it only names a payment to
+// re-read. Everything acted on comes from the confirming GetPayment. A succeeded payment credits its
+// order exactly once (idempotent, and honoured even if the order expired); a canceled one records a
+// failed event so the customer is told the attempt did not go through.
+//
+// The reply tells the provider whether to redeliver: 200 for anything durably decided — including a
+// duplicate and a permanent rejection, which no retry could fix — and 5xx only for a transient
+// failure we want redelivered (YooKassa retries for 24 hours). An unrecognised sender is a 403,
+// which is also redelivered: if YooKassa ever changed its published ranges, the retries plus the
+// reconcile sweep would keep the money owed while the allowlist is corrected.
+func (s *Server) handleYooKassaNotify(c *gin.Context) {
+	// The sender check runs before anything else. It is defence in depth — the confirming GetPayment
+	// is what actually establishes authenticity — but it is what stops a forger from turning each
+	// fabricated notification into an outbound API call of ours. The address is the true sender,
+	// forwarded by the gateway, which is the only hop that sees it.
+	if ip := clientIP(c); !yookassa.AllowedSender(ip) {
+		s.log.Warn("yookassa notify: sender is not a YooKassa address", zap.String("ip", ip))
+		c.String(http.StatusForbidden, "forbidden")
+		return
+	}
+	raw, err := io.ReadAll(io.LimitReader(c.Request.Body, maxNotifyBytes))
+	if err != nil {
+		c.String(http.StatusInternalServerError, "error")
+		return
+	}
+	note, err := yookassa.ParseNotification(raw)
+	if err != nil {
+		s.log.Warn("yookassa notify: malformed body", zap.Error(err))
+		c.String(http.StatusOK, "ignored")
+		return
+	}
+	switch note.Event {
+	case yookassa.EventPaymentSucceeded, yookassa.EventPaymentCanceled:
+	default:
+		// Refund events are informational: refunds are issued through the API, which records them
+		// synchronously. Anything else is a subscription we do not act on.
+		c.String(http.StatusOK, "ignored")
+		return
+	}
+	claimed, err := note.Payment()
+	if err != nil {
+		s.log.Warn("yookassa notify: unusable payment object", zap.String("event", note.Event), zap.Error(err))
+		c.String(http.StatusOK, "ignored")
+		return
+	}
+	orderID, err := uuid.Parse(claimed.OrderID())
+	if err != nil {
+		s.log.Warn("yookassa notify: no order in payment metadata", zap.String("payment", claimed.ID))
+		c.String(http.StatusOK, "ignored")
+		return
+	}
+
+	ctx := c.Request.Context()
+	ref, err := s.payments.OrderProviderRef(ctx, orderID)
+	if errors.Is(err, payments.ErrOrderNotFound) {
+		s.log.Warn("yookassa notify: unknown order", zap.String("order", orderID.String()), zap.String("payment", claimed.ID))
+		c.String(http.StatusOK, "ignored")
+		return
+	}
+	if err != nil {
+		s.log.Error("yookassa notify: order lookup failed", zap.String("order", orderID.String()), zap.Error(err))
+		c.String(http.StatusInternalServerError, "error")
+		return
+	}
+
+	payment, shop, err := s.confirmYooKassaPayment(ctx, claimed.ID, claimed.Recipient.AccountID, ref)
+	if err != nil {
+		var apiErr *yookassa.APIError
+		if errors.As(err, &apiErr) && !apiErr.Retryable() {
+			// The provider says this payment is not ours or not readable — a forged or stale
+			// notification. Nothing to redeliver.
+			s.log.Warn("yookassa notify: payment not confirmed",
+				zap.String("order", orderID.String()), zap.String("payment", claimed.ID), zap.Error(err))
+			c.String(http.StatusOK, "ignored")
+			return
+		}
+		s.log.Error("yookassa notify: confirm failed",
+			zap.String("order", orderID.String()), zap.String("payment", claimed.ID), zap.Error(err))
+		c.String(http.StatusInternalServerError, "error")
+		return
+	}
+	if !s.yooKassaPaymentMatchesOrder(payment, shop, orderID) {
+		c.String(http.StatusOK, "ignored")
+		return
+	}
+
+	switch payment.Status {
+	case yookassa.StatusSucceeded:
+		if err := s.creditYooKassaPayment(ctx, orderID, payment); err != nil {
+			if isPermanentFundError(err) {
+				s.log.Warn("yookassa notify rejected", zap.String("order", orderID.String()), zap.Error(err))
+				c.String(http.StatusOK, "rejected")
+				return
+			}
+			s.log.Error("yookassa fund failed", zap.String("order", orderID.String()), zap.Error(err))
+			c.String(http.StatusInternalServerError, "error")
+			return
+		}
+	case yookassa.StatusCanceled:
+		// An active decline (§9): the customer is told the attempt failed. An order abandoned without
+		// a decline never reaches here — it just expires, invisibly.
+		s.recordYooKassaFailure(ctx, ref.AccountID, orderID, payment)
+	default:
+		// Still pending: the notification raced ahead of the payment, or was forged. Either way the
+		// reconcile sweep will settle the order, so there is nothing to redeliver.
+		s.log.Info("yookassa notify: payment not final",
+			zap.String("order", orderID.String()), zap.String("status", payment.Status))
+	}
+	c.String(http.StatusOK, "ok")
+}
+
+// confirmYooKassaPayment re-reads a payment from the API — the authenticity check for the whole rail,
+// since notifications are unsigned. The shop is chosen by the shop id the payment claims to have been
+// paid to, falling back to the merchant channel recorded on the order; a claim naming a shop we do
+// not run is not honoured with our own credentials.
+func (s *Server) confirmYooKassaPayment(ctx context.Context, paymentID, claimedShopID string, ref payments.OrderRef) (yookassa.Payment, yookassa.Config, error) {
+	_, shop, ok := s.yookassa.ByShopID(claimedShopID)
+	if !ok {
+		shop, ok = s.yookassa.Shop(ref.Shop)
+	}
+	if !ok {
+		return yookassa.Payment{}, yookassa.Config{}, yookassa.ErrUnconfigured
+	}
+	payment, err := shop.GetPayment(ctx, paymentID)
+	return payment, shop, err
+}
+
+// yooKassaPaymentMatchesOrder checks the confirmed payment really belongs to the order being
+// credited and to the kind of shop we think it is. It rejects a payment whose metadata names a
+// different order, and — the guard that keeps play money out of the live ledger — a live payment
+// arriving on test credentials or a test payment on live ones.
+func (s *Server) yooKassaPaymentMatchesOrder(payment yookassa.Payment, shop yookassa.Config, orderID uuid.UUID) bool {
+	if payment.OrderID() != orderID.String() {
+		s.log.Warn("yookassa: confirmed payment belongs to another order",
+			zap.String("order", orderID.String()), zap.String("payment", payment.ID),
+			zap.String("payment_order", payment.OrderID()))
+		return false
+	}
+	if payment.Test != shop.IsTest {
+		s.log.Error("yookassa: payment test flag does not match the shop; refusing to credit",
+			zap.String("order", orderID.String()), zap.String("payment", payment.ID),
+			zap.Bool("payment_test", payment.Test), zap.Bool("shop_test", shop.IsTest))
+		return false
+	}
+	return true
+}
+
+// creditYooKassaPayment credits a confirmed succeeded payment to its order exactly once and records
+// the succeeded event a duplicate must not re-emit.
+func (s *Server) creditYooKassaPayment(ctx context.Context, orderID uuid.UUID, payment yookassa.Payment) error {
+	paid, err := payments.ParseMoney(payment.Amount.Value, payments.Currency(payment.Amount.Currency))
+	if err != nil {
+		return err
+	}
+	outcome, err := s.payments.Fund(ctx, orderID, providerYooKassa, payment.ID, paid)
+	if err != nil {
+		return err
+	}
+	if outcome.AlreadyCredited {
+		return nil
+	}
+	payload, _ := json.Marshal(map[string]any{"chips": outcome.Chips, "source": string(outcome.Source)})
+	if err := s.payments.RecordPaymentEvent(ctx, outcome.AccountID, &orderID, "succeeded", payload); err != nil {
+		// The credit is already committed; only the in-app notification is lost, and the wallet still
+		// refreshes on the client's return.
+		s.log.Error("record payment event failed", zap.String("order", orderID.String()), zap.Error(err))
+	}
+	return nil
+}
+
+// recordYooKassaFailure records the failed payment event for an actively declined payment, so the
+// customer learns the attempt did not go through instead of watching a balance that never moves.
+func (s *Server) recordYooKassaFailure(ctx context.Context, accountID uuid.UUID, orderID uuid.UUID, payment yookassa.Payment) {
+	reason := ""
+	if payment.CancellationDetails != nil {
+		reason = payment.CancellationDetails.Reason
+	}
+	s.log.Info("yookassa payment canceled",
+		zap.String("order", orderID.String()), zap.String("payment", payment.ID), zap.String("reason", reason))
+	payload, _ := json.Marshal(map[string]any{"reason": reason})
+	if err := s.payments.RecordPaymentEvent(ctx, accountID, &orderID, "failed", payload); err != nil {
+		s.log.Error("record payment event failed", zap.String("order", orderID.String()), zap.Error(err))
+	}
+}
+
+// isPermanentFundError reports whether a credit failed for a reason no retry can fix — an order that
+// does not exist, an amount that does not match, or a product that is no longer a chip pack.
+func isPermanentFundError(err error) bool {
+	return errors.Is(err, payments.ErrOrderNotFound) || errors.Is(err, payments.ErrAmountMismatch) ||
+		errors.Is(err, payments.ErrNotAPack) || errors.Is(err, payments.ErrProductNotFound)
+}
+
+// refundYooKassa returns the money for a paid order through the YooKassa refund API and reports the
+// provider's own refund id, which the ledger then records. The refund carries a receipt because the
+// rail registers a refund receipt the same way it registers a payment one, and the order id as the
+// idempotency key, so a repeated attempt returns the original refund instead of paying twice.
+//
+// It is called before anything is recorded: if the money does not move, nothing is written, and the
+// ledger never claims a refund that did not happen.
+func (s *Server) refundYooKassa(ctx context.Context, ref payments.OrderRef) (string, error) {
+	shop, ok := s.yookassa.Shop(ref.Shop)
+	if !ok {
+		return "", yookassa.ErrUnconfigured
+	}
+	if ref.PaymentID == "" {
+		return "", errors.New("the order carries no provider payment id to refund")
+	}
+	title, _, err := s.payments.OrderItem(ctx, ref.OrderID)
+	if err != nil {
+		return "", err
+	}
+	email, _, err := s.accounts.ConfirmedEmail(ctx, ref.AccountID)
+	if err != nil {
+		return "", err
+	}
+	amount := yookassa.Amount{Value: ref.Amount.Major(), Currency: string(ref.Amount.Currency())}
+	refund, err := shop.CreateRefund(ctx, yookassa.RefundRequest{
+		PaymentID: ref.PaymentID,
+		Amount:    amount,
+		Receipt:   yookassa.SingleItemReceipt(email, title, amount, s.vatCode),
+	}, ref.OrderID.String())
+	if err != nil {
+		return "", err
+	}
+	if refund.ID == "" {
+		return "", errors.New("the provider returned a refund with no id")
+	}
+	return refund.ID, nil
+}
+
+// ReconcileYooKassaOrders asks YooKassa what became of every pending order that reached its expiry
+// age while carrying a payment id, and credits the ones that were in fact paid. It is the safety net
+// for a notification that was lost for good: YooKassa redelivers for 24 hours, so a short outage
+// heals itself, but a notification that never arrived at all would otherwise leave the money taken
+// and the chips unowed. It runs once per order, just before the order is written off as expired.
+//
+// It returns how many orders it credited. Failures are logged and skipped: the next sweep retries.
+func (s *Server) ReconcileYooKassaOrders(ctx context.Context) int {
+	if !s.yookassa.Configured() || s.payments == nil {
+		return 0
+	}
+	refs, err := s.payments.PendingForReconcile(ctx)
+	if err != nil {
+		s.log.Warn("yookassa reconcile: read pending orders failed", zap.Error(err))
+		return 0
+	}
+	credited := 0
+	for _, ref := range refs {
+		if ref.Provider != providerYooKassa || ref.PaymentID == "" {
+			continue
+		}
+		shop, ok := s.yookassa.Shop(ref.Shop)
+		if !ok {
+			continue
+		}
+		payment, err := shop.GetPayment(ctx, ref.PaymentID)
+		if err != nil {
+			s.log.Warn("yookassa reconcile: payment lookup failed",
+				zap.String("order", ref.OrderID.String()), zap.String("payment", ref.PaymentID), zap.Error(err))
+			continue
+		}
+		if payment.Status != yookassa.StatusSucceeded || !s.yooKassaPaymentMatchesOrder(payment, shop, ref.OrderID) {
+			continue
+		}
+		if err := s.creditYooKassaPayment(ctx, ref.OrderID, payment); err != nil {
+			s.log.Error("yookassa reconcile: credit failed",
+				zap.String("order", ref.OrderID.String()), zap.Error(err))
+			continue
+		}
+		s.log.Info("yookassa reconcile: credited an order no notification confirmed",
+			zap.String("order", ref.OrderID.String()), zap.String("payment", payment.ID))
+		credited++
+	}
+	return credited
+}

backend/internal/server/server.go

@@ -36,6 +36,7 @@ import (
 	"scrabble/backend/internal/session"
 	"scrabble/backend/internal/social"
 	"scrabble/backend/internal/telemetry"
+	"scrabble/backend/internal/yookassa"
 )
 
 // shutdownTimeout bounds how long Run waits for in-flight requests to finish
@@ -115,8 +116,18 @@ type Deps struct {
 	// Renderer is the image-render sidecar client for the PNG export artifact. A
 	// nil Renderer makes the PNG download answer 404 (the GCG artifact still works).
 	Renderer *render.Client
-	// Robokassa configures the direct-rail (RUB) provider — one merchant shop per channel; an empty
-	// set leaves the order and Result-callback endpoints unregistered.
+	// YooKassa configures the direct-rail (RUB) provider — one merchant shop per channel; an empty
+	// set leaves the order and notification endpoints unregistered and falls the direct rail back to
+	// Robokassa.
+	YooKassa yookassa.Shops
+	// YooKassaVatCode is the VAT rate code stamped on every fiscal receipt line (54-ФЗ tag 1199).
+	YooKassaVatCode int
+	// PublicBaseURL is the canonical https origin the payment return URL is built from. It is
+	// required whenever YooKassa is configured.
+	PublicBaseURL string
+	// Robokassa configures the retired direct-rail provider — one merchant shop per channel. No
+	// deployment sets it, so the set is empty and the direct rail resolves to YooKassa; it stays
+	// wired so restoring the rail is a credentials change (backend/internal/robokassa/README.md).
 	Robokassa robokassa.Shops
 }
 
@@ -146,6 +157,9 @@ type Server struct {
 	ads         *ads.Service
 	payments    *payments.Service
 	gamelimits  *gamelimits.Service
+	yookassa    yookassa.Shops
+	vatCode     int
+	publicURL   string
 	robokassa   robokassa.Shops
 	notifier    notify.Publisher
 	console     *adminconsole.Renderer
@@ -201,6 +215,9 @@ func New(addr string, deps Deps) *Server {
 		ads:           deps.Ads,
 		payments:      deps.Payments,
 		gamelimits:    deps.GameLimits,
+		yookassa:      deps.YooKassa,
+		vatCode:       deps.YooKassaVatCode,
+		publicURL:     deps.PublicBaseURL,
 		robokassa:     deps.Robokassa,
 		notifier:      notifier,
 		renderer:      deps.Renderer,

backend/internal/yookassa/notify.go

@@ -0,0 +1,98 @@
+package yookassa
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/netip"
+)
+
+// Notification events this integration subscribes to. An event name is "<object>.<status>": the
+// object whose status changed and the status it entered.
+const (
+	// EventPaymentSucceeded means the money was taken and the order may be credited.
+	EventPaymentSucceeded = "payment.succeeded"
+	// EventPaymentCanceled means the payment was actively declined or abandoned; nothing is credited
+	// and the payer is told the attempt failed.
+	EventPaymentCanceled = "payment.canceled"
+	// EventRefundSucceeded reports a completed refund. Refunds here are always initiated by an
+	// operator through the API, which records them synchronously, so this event is informational.
+	EventRefundSucceeded = "refund.succeeded"
+)
+
+// notificationType is the fixed value of a notification envelope's type field.
+const notificationType = "notification"
+
+// Notification is an incoming webhook envelope. Object is left raw because its shape depends on the
+// event — a payment for payment.*, a refund for refund.* — and because nothing in it may be acted on
+// before GetPayment confirms it: YooKassa does not sign notifications.
+type Notification struct {
+	Type   string          `json:"type"`
+	Event  string          `json:"event"`
+	Object json.RawMessage `json:"object"`
+}
+
+// ParseNotification decodes a webhook body and checks the envelope is a notification with an event.
+// It deliberately validates nothing else: the body is untrusted input whose only job is to name an
+// object to re-read from the API.
+func ParseNotification(body []byte) (Notification, error) {
+	var n Notification
+	if err := json.Unmarshal(body, &n); err != nil {
+		return Notification{}, fmt.Errorf("yookassa: decode notification: %w", err)
+	}
+	if n.Type != notificationType || n.Event == "" {
+		return Notification{}, fmt.Errorf("yookassa: not a notification envelope (type %q, event %q)", n.Type, n.Event)
+	}
+	return n, nil
+}
+
+// Payment decodes the notification's object as a payment. Use it only for payment.* events; it
+// yields the payment id to re-read, never the payment state to act on.
+func (n Notification) Payment() (Payment, error) {
+	var p Payment
+	if err := json.Unmarshal(n.Object, &p); err != nil {
+		return Payment{}, fmt.Errorf("yookassa: decode notification payment: %w", err)
+	}
+	if p.ID == "" {
+		return Payment{}, fmt.Errorf("yookassa: notification payment has no id")
+	}
+	return p, nil
+}
+
+// senderPrefixes are the address ranges YooKassa delivers notifications from
+// (https://yookassa.ru/developers/using-api/webhooks). Single addresses are expressed as /32 and
+// /128 prefixes. The list is defence in depth only — the confirming GetPayment is what actually
+// establishes authenticity — so it is kept deliberately literal and easy to audit against the docs.
+var senderPrefixes = []netip.Prefix{
+	netip.MustParsePrefix("185.71.76.0/27"),
+	netip.MustParsePrefix("185.71.77.0/27"),
+	netip.MustParsePrefix("77.75.153.0/25"),
+	netip.MustParsePrefix("77.75.156.11/32"),
+	netip.MustParsePrefix("77.75.156.35/32"),
+	netip.MustParsePrefix("77.75.154.128/25"),
+	netip.MustParsePrefix("2a02:5180::/32"),
+}
+
+// AllowedIP reports whether addr is one of YooKassa's notification senders. An IPv4-mapped IPv6
+// address is unmapped first, so a dual-stack listener's view of an IPv4 sender still matches.
+func AllowedIP(addr netip.Addr) bool {
+	addr = addr.Unmap()
+	if !addr.IsValid() {
+		return false
+	}
+	for _, p := range senderPrefixes {
+		if p.Contains(addr) {
+			return true
+		}
+	}
+	return false
+}
+
+// AllowedSender reports whether the textual address ip is one of YooKassa's notification senders. An
+// unparseable address is not allowed.
+func AllowedSender(ip string) bool {
+	addr, err := netip.ParseAddr(ip)
+	if err != nil {
+		return false
+	}
+	return AllowedIP(addr)
+}

backend/internal/yookassa/notify_test.go

@@ -0,0 +1,90 @@
+package yookassa
+
+import (
+	"testing"
+)
+
+func TestParseNotification(t *testing.T) {
+	n, err := ParseNotification([]byte(`{"type":"notification","event":"payment.succeeded",
+		"object":{"id":"pay-1","status":"succeeded","paid":true,"metadata":{"order_id":"0197-order"}}}`))
+	if err != nil {
+		t.Fatalf("parse notification: %v", err)
+	}
+	if n.Event != EventPaymentSucceeded {
+		t.Errorf("event = %q, want %q", n.Event, EventPaymentSucceeded)
+	}
+	p, err := n.Payment()
+	if err != nil {
+		t.Fatalf("decode notification payment: %v", err)
+	}
+	if p.ID != "pay-1" {
+		t.Errorf("payment id = %q, want pay-1", p.ID)
+	}
+	if p.OrderID() != "0197-order" {
+		t.Errorf("order id = %q, want the order carried in metadata", p.OrderID())
+	}
+}
+
+func TestParseNotificationRejectsNonEnvelopes(t *testing.T) {
+	for name, body := range map[string]string{
+		"not json":     `nonsense`,
+		"wrong type":   `{"type":"payment","event":"payment.succeeded","object":{"id":"pay-1"}}`,
+		"no event":     `{"type":"notification","object":{"id":"pay-1"}}`,
+		"empty object": `{}`,
+	} {
+		if _, err := ParseNotification([]byte(body)); err == nil {
+			t.Errorf("%s: accepted as a notification envelope", name)
+		}
+	}
+}
+
+func TestNotificationPaymentNeedsAnID(t *testing.T) {
+	// Without an id there is nothing to re-read from the API, and the body itself is never evidence.
+	n, err := ParseNotification([]byte(`{"type":"notification","event":"payment.succeeded","object":{"status":"succeeded"}}`))
+	if err != nil {
+		t.Fatalf("parse notification: %v", err)
+	}
+	if _, err := n.Payment(); err == nil {
+		t.Error("a payment object with no id was accepted")
+	}
+}
+
+func TestAllowedSender(t *testing.T) {
+	allowed := []string{
+		"185.71.76.0", "185.71.76.31", // /27 bounds
+		"185.71.77.15",
+		"77.75.153.0", "77.75.153.127", // /25 bounds
+		"77.75.156.11", "77.75.156.35", // the two single addresses
+		"77.75.154.128", "77.75.154.255",
+		"2a02:5180::1", "2a02:5180:ffff::abcd",
+	}
+	for _, ip := range allowed {
+		if !AllowedSender(ip) {
+			t.Errorf("%s rejected, want allowed", ip)
+		}
+	}
+	denied := []string{
+		"185.71.76.32", "185.71.75.255", // just outside the /27
+		"77.75.153.128", // just outside the /25
+		"77.75.156.12",  // adjacent to a single allowed address
+		"77.75.154.127",
+		"2a02:5181::1",
+		"8.8.8.8", "127.0.0.1", "",
+		"not an address",
+	}
+	for _, ip := range denied {
+		if AllowedSender(ip) {
+			t.Errorf("%s allowed, want rejected", ip)
+		}
+	}
+}
+
+func TestAllowedSenderUnmapsIPv4(t *testing.T) {
+	// A dual-stack listener reports an IPv4 peer as ::ffff:a.b.c.d; it must still match the v4 range.
+	if !AllowedSender("::ffff:77.75.156.11") {
+		t.Error("an IPv4-mapped allowed sender was rejected")
+	}
+	if AllowedSender("::ffff:8.8.8.8") {
+		t.Error("an IPv4-mapped foreign sender was allowed")
+	}
+}

backend/internal/yookassa/receipt.go

@@ -0,0 +1,82 @@
+package yookassa
+
+// Fiscal receipt attributes for «Чеки от ЮKassa» (54-ФЗ). YooKassa registers the receipt itself —
+// no cash register to rent, no OFD contract — but only if the payment and refund requests carry a
+// receipt object, so unlike the previous rail's cabinet-side receipts these fields are load-bearing
+// code. Reference:
+// https://yookassa.ru/developers/payment-acceptance/receipts/54fz/yoomoney/parameters-values
+const (
+	// PaymentSubjectService is the settlement subject (54-ФЗ tag 1212) — what the money is taken
+	// for. Chips are sold as a service ("Услуга").
+	PaymentSubjectService = "service"
+	// PaymentModeFullPayment is the settlement method (54-ФЗ tag 1214) — the payer pays and receives
+	// the goods at once ("Полный расчет"). «Чеки от ЮKassa» accept only this and full_prepayment;
+	// partial prepayment, advance and credit are not supported.
+	PaymentModeFullPayment = "full_payment"
+
+	// VatCodeNone is the VAT rate code (54-ФЗ tag 1199) for «Без НДС» — the rate a sole proprietor on
+	// УСН or ПСН charges. It is the default; the deployed value is configurable because the rate is
+	// the one receipt attribute that genuinely changes (Russia raised the main rate on 1 Jan 2026,
+	// adding codes 11 and 12).
+	VatCodeNone = 1
+	// VatCodeMax is the highest VAT rate code the API accepts; codes run 1..12.
+	VatCodeMax = 12
+)
+
+// Customer is the payer's contact data for delivering the receipt. «Чеки от ЮKassa» deliver only by
+// email (no SMS), so Email is required — the direct rail's confirmed email anchor supplies it.
+type Customer struct {
+	Email string `json:"email,omitempty"`
+}
+
+// ReceiptItem is one line of a fiscal receipt: what was sold, how much of it, for how much, and the
+// three fiscal attributes that classify it.
+type ReceiptItem struct {
+	Description    string  `json:"description"`
+	Quantity       float64 `json:"quantity"`
+	Amount         Amount  `json:"amount"`
+	VatCode        int     `json:"vat_code"`
+	PaymentSubject string  `json:"payment_subject"`
+	PaymentMode    string  `json:"payment_mode"`
+}
+
+// Receipt is the fiscal receipt data sent alongside a payment or a refund. tax_system_code is
+// deliberately absent: YooKassa ignores it for «Чеки от ЮKassa».
+type Receipt struct {
+	Customer Customer      `json:"customer"`
+	Items    []ReceiptItem `json:"items"`
+}
+
+// maxDescriptionRunes is the API's limit for both a payment description and a receipt line
+// description (54-ФЗ tag 1030). A longer title is truncated rather than rejected, so an over-long
+// product name cannot block a purchase.
+const maxDescriptionRunes = 128
+
+// SingleItemReceipt builds a one-line receipt for selling title at amount to email. Chip packs are
+// always a single line bought once, so quantity is 1 and the line amount is the whole payment.
+func SingleItemReceipt(email, title string, amount Amount, vatCode int) *Receipt {
+	return &Receipt{
+		Customer: Customer{Email: email},
+		Items: []ReceiptItem{{
+			Description:    TruncateDescription(title),
+			Quantity:       1,
+			Amount:         amount,
+			VatCode:        vatCode,
+			PaymentSubject: PaymentSubjectService,
+			PaymentMode:    PaymentModeFullPayment,
+		}},
+	}
+}
+
+// TruncateDescription shortens s to the API's description limit, counting runes rather than bytes so
+// a Cyrillic title is not cut mid-character.
+func TruncateDescription(s string) string {
+	r := []rune(s)
+	if len(r) <= maxDescriptionRunes {
+		return s
+	}
+	return string(r[:maxDescriptionRunes])
+}
+
+// ValidVatCode reports whether code is within the range the API accepts (1..12).
+func ValidVatCode(code int) bool { return code >= 1 && code <= VatCodeMax }

backend/internal/yookassa/shops.go

@@ -0,0 +1,58 @@
+package yookassa
+
+// Shops is a set of YooKassa merchant shops keyed by channel — the subtype of the trusted X-Platform
+// signal for the direct rail ("web", "android"; "ios" later). The direct rail routes a payment to the
+// per-channel shop for separate merchant accounts, accounting and receipts, while every shop still
+// credits the one direct wallet (docs/PAYMENTS_DECISIONS_ru.md D42). An empty set leaves the direct
+// order and notification endpoints unregistered.
+type Shops map[string]Config
+
+// Channel constants name the direct-rail X-Platform subtypes a shop is keyed by. ChannelWeb is the
+// default: an unknown or empty channel routes here on the order side.
+const (
+	ChannelWeb     = "web"
+	ChannelAndroid = "android"
+)
+
+// Shop returns the shop that issues an order for channel, falling back to the web shop when channel
+// is unknown, empty or not configured. The fallback is safe: routing only chooses the merchant
+// account and receipt, never the credited wallet (always direct, D42), so a mis-attributed channel
+// costs at most accounting accuracy, not money. The second result is false when neither the channel
+// nor the web shop is configured.
+func (s Shops) Shop(channel string) (Config, bool) {
+	if channel != "" {
+		if c, ok := s[channel]; ok && c.Configured() {
+			return c, true
+		}
+	}
+	if c, ok := s[ChannelWeb]; ok && c.Configured() {
+		return c, true
+	}
+	return Config{}, false
+}
+
+// ByShopID returns the shop with the given YooKassa shop id, which is how an incoming notification is
+// attributed to one of several configured shops (the payment object reports it as
+// recipient.account_id). Unlike Shop it does not fall back: an unrecognised shop id means the
+// notification was not meant for us, and the caller must not guess at credentials.
+func (s Shops) ByShopID(shopID string) (channel string, cfg Config, ok bool) {
+	if shopID == "" {
+		return "", Config{}, false
+	}
+	for ch, c := range s {
+		if c.Configured() && c.ShopID == shopID {
+			return ch, c, true
+		}
+	}
+	return "", Config{}, false
+}
+
+// Configured reports whether at least one shop has credentials (the YooKassa direct rail is live).
+func (s Shops) Configured() bool {
+	for _, c := range s {
+		if c.Configured() {
+			return true
+		}
+	}
+	return false
+}

backend/internal/yookassa/shops_test.go

@@ -0,0 +1,112 @@
+package yookassa
+
+import (
+	"strings"
+	"testing"
+)
+
+func testShops() Shops {
+	return Shops{
+		ChannelWeb:     {ShopID: "100500", SecretKey: "web-secret"},
+		ChannelAndroid: {ShopID: "100700", SecretKey: "android-secret"},
+	}
+}
+
+func TestShopsShopRouting(t *testing.T) {
+	s := testShops()
+	for channel, wantShopID := range map[string]string{
+		ChannelWeb:     "100500",
+		ChannelAndroid: "100700",
+		"ios":          "100500", // an unconfigured channel falls back to web
+		"":             "100500", // so does an unknown platform subtype
+	} {
+		got, ok := s.Shop(channel)
+		if !ok || got.ShopID != wantShopID {
+			t.Errorf("Shop(%q) = %q ok=%v, want %q", channel, got.ShopID, ok, wantShopID)
+		}
+	}
+}
+
+func TestShopsShopWithoutWebFallback(t *testing.T) {
+	// Only android configured: an unknown channel has nowhere safe to fall back to.
+	s := Shops{ChannelAndroid: {ShopID: "100700", SecretKey: "android-secret"}}
+	if got, ok := s.Shop(ChannelAndroid); !ok || got.ShopID != "100700" {
+		t.Errorf("Shop(android) = %q ok=%v, want the android shop", got.ShopID, ok)
+	}
+	if _, ok := s.Shop("ios"); ok {
+		t.Error("Shop(ios) resolved with no web shop configured")
+	}
+	if _, ok := (Shops{}).Shop(ChannelWeb); ok {
+		t.Error("an empty set resolved a shop")
+	}
+}
+
+func TestShopsByShopIDDoesNotGuess(t *testing.T) {
+	s := testShops()
+	channel, cfg, ok := s.ByShopID("100700")
+	if !ok || channel != ChannelAndroid || cfg.SecretKey != "android-secret" {
+		t.Errorf("ByShopID(100700) = %q/%q ok=%v, want the android shop", channel, cfg.SecretKey, ok)
+	}
+	// An unrecognised shop id means the notification was not meant for us; guessing at credentials
+	// would verify a foreign payment against our own shop.
+	for _, id := range []string{"999999", ""} {
+		if _, _, ok := s.ByShopID(id); ok {
+			t.Errorf("ByShopID(%q) resolved a shop", id)
+		}
+	}
+}
+
+func TestShopsIgnoreHalfConfiguredEntries(t *testing.T) {
+	s := Shops{
+		ChannelWeb:     {ShopID: "100500"}, // no secret key
+		ChannelAndroid: {SecretKey: "android-secret"},
+	}
+	if s.Configured() {
+		t.Error("Configured() = true with no complete shop")
+	}
+	if _, ok := s.Shop(ChannelWeb); ok {
+		t.Error("Shop(web) resolved a shop with no secret key")
+	}
+	if _, _, ok := s.ByShopID("100500"); ok {
+		t.Error("ByShopID matched a shop with no secret key")
+	}
+}
+
+func TestShopsConfigured(t *testing.T) {
+	if !testShops().Configured() {
+		t.Error("Configured() = false with two complete shops")
+	}
+	if (Shops{}).Configured() {
+		t.Error("Configured() = true for an empty set")
+	}
+}
+
+func TestSingleItemReceiptTruncatesLongTitles(t *testing.T) {
+	long := strings.Repeat("ф", 200) // Cyrillic: truncation must count runes, not bytes
+	r := SingleItemReceipt("buyer@example.test", long, Amount{Value: "1.00", Currency: "RUB"}, VatCodeNone)
+	got := []rune(r.Items[0].Description)
+	if len(got) != maxDescriptionRunes {
+		t.Errorf("description = %d runes, want %d", len(got), maxDescriptionRunes)
+	}
+	for _, c := range got {
+		if c != 'ф' {
+			t.Fatalf("truncation cut a multi-byte rune: %q", string(got))
+		}
+	}
+	if r.Items[0].Quantity != 1 {
+		t.Errorf("quantity = %v, want 1 (a chip pack is bought once)", r.Items[0].Quantity)
+	}
+}
+
+func TestValidVatCode(t *testing.T) {
+	for _, code := range []int{1, 4, 11, 12} {
+		if !ValidVatCode(code) {
+			t.Errorf("vat code %d rejected, want accepted", code)
+		}
+	}
+	for _, code := range []int{0, -1, 13} {
+		if ValidVatCode(code) {
+			t.Errorf("vat code %d accepted, want rejected", code)
+		}
+	}
+}

backend/internal/yookassa/yookassa.go

@@ -0,0 +1,271 @@
+// Package yookassa talks to the YooKassa REST API for the direct-rail (RUB) payments: it creates a
+// hosted payment the client is redirected to, re-reads a payment to confirm what really happened,
+// and issues a refund. It is pure provider glue — no database, no payments-domain coupling — so the
+// payments domain stays provider-agnostic and this layer is unit-testable in isolation.
+//
+// Two properties of the API shape everything here. First, YooKassa notifications carry NO signature:
+// authenticity is established by re-reading the object with GetPayment (the notification body is a
+// hint, never evidence) and, defensively, by the sender-IP allowlist in AllowedIP. Second, every
+// state-changing call is made idempotent by an Idempotence-Key header, so a retried create or refund
+// returns the original object instead of charging twice; callers pass the order id as that key.
+//
+// The order is threaded to the provider through metadata["order_id"] and echoed back on the payment,
+// so a notification resolves to an order without trusting anything else in the body.
+package yookassa
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"strings"
+	"time"
+)
+
+// DefaultBaseURL is the production API root. Config.BaseURL overrides it (tests point it at an
+// httptest server).
+const DefaultBaseURL = "https://api.yookassa.ru/v3"
+
+// MetadataOrderID is the metadata key carrying our order id through the provider and back on the
+// payment object — the only link a notification gives us to an order.
+const MetadataOrderID = "order_id"
+
+// Payment statuses (https://yookassa.ru/developers/payment-acceptance/getting-started/payment-process).
+// A single-stage payment (Capture true) moves pending -> succeeded or pending -> canceled;
+// StatusWaitingForCapture only occurs for two-stage payments, which this integration does not use.
+const (
+	StatusPending           = "pending"
+	StatusWaitingForCapture = "waiting_for_capture"
+	StatusSucceeded         = "succeeded"
+	StatusCanceled          = "canceled"
+)
+
+// ConfirmationRedirect is the confirmation scenario this integration uses: YooKassa hosts the
+// payment form and returns the customer to the return URL afterwards.
+const ConfirmationRedirect = "redirect"
+
+// requestTimeout bounds a single API call. The caller's context still governs cancellation; this is
+// the ceiling for a provider that has stopped answering.
+const requestTimeout = 20 * time.Second
+
+// maxResponseBytes caps how much of a response body is read, so a misbehaving or spoofed endpoint
+// cannot exhaust memory.
+const maxResponseBytes = 1 << 20
+
+// apiClient is shared by every shop so connections pool across them. It carries only a ceiling
+// timeout; per-request cancellation rides the context.
+var apiClient = &http.Client{Timeout: requestTimeout}
+
+// Config is a YooKassa merchant shop's credentials. ShopID and SecretKey authenticate every call as
+// HTTP Basic credentials. IsTest records that these are a test shop's credentials, which lets the
+// caller refuse to credit a live payment against a test shop and vice versa. BaseURL overrides
+// DefaultBaseURL when set.
+type Config struct {
+	ShopID    string
+	SecretKey string
+	IsTest    bool
+	BaseURL   string
+}
+
+// Amount is a monetary amount on the wire: a decimal string with the fraction separator "." and an
+// ISO-4217 currency code. payments.Money.Major() already renders Value in this form.
+type Amount struct {
+	Value    string `json:"value"`
+	Currency string `json:"currency"`
+}
+
+// Confirmation carries the confirmation scenario. ReturnURL is sent on a create (where the customer
+// lands after paying, absolute); ConfirmationURL comes back on the created payment and is the page
+// the customer must be sent to.
+type Confirmation struct {
+	Type            string `json:"type"`
+	ReturnURL       string `json:"return_url,omitempty"`
+	ConfirmationURL string `json:"confirmation_url,omitempty"`
+}
+
+// Recipient identifies the shop that received the payment. AccountID is the shop id, which is how an
+// incoming notification is attributed to one of several configured shops.
+type Recipient struct {
+	AccountID string `json:"account_id"`
+	GatewayID string `json:"gateway_id"`
+}
+
+// Cancellation explains a canceled payment: which participant decided (yoo_money, payment_network,
+// merchant) and why. It is reported to the operator, not to the payer.
+type Cancellation struct {
+	Party  string `json:"party"`
+	Reason string `json:"reason"`
+}
+
+// PaymentRequest is the body of a create-payment call in the redirect confirmation scenario. Capture
+// true settles in one stage: a paid payment goes straight to succeeded with no capture call.
+type PaymentRequest struct {
+	Amount       Amount            `json:"amount"`
+	Capture      bool              `json:"capture"`
+	Confirmation Confirmation      `json:"confirmation"`
+	Description  string            `json:"description,omitempty"`
+	Metadata     map[string]string `json:"metadata,omitempty"`
+	Receipt      *Receipt          `json:"receipt,omitempty"`
+}
+
+// Payment is a YooKassa payment object. Paid reports that the money was actually taken; Test is true
+// for a payment made against a test shop. Metadata echoes what the create call sent, so
+// Metadata[MetadataOrderID] identifies the order.
+type Payment struct {
+	ID                  string            `json:"id"`
+	Status              string            `json:"status"`
+	Paid                bool              `json:"paid"`
+	Test                bool              `json:"test"`
+	Amount              Amount            `json:"amount"`
+	Description         string            `json:"description"`
+	Confirmation        Confirmation      `json:"confirmation"`
+	Metadata            map[string]string `json:"metadata"`
+	Recipient           Recipient         `json:"recipient"`
+	CancellationDetails *Cancellation     `json:"cancellation_details,omitempty"`
+}
+
+// OrderID returns the order the payment funds, taken from the metadata the create call threaded
+// through. It is empty for a payment we did not originate.
+func (p Payment) OrderID() string { return p.Metadata[MetadataOrderID] }
+
+// RefundRequest is the body of a create-refund call. Amount may be the whole payment or part of it;
+// Receipt carries the refund receipt required when the shop registers receipts through YooKassa.
+type RefundRequest struct {
+	PaymentID   string   `json:"payment_id"`
+	Amount      Amount   `json:"amount"`
+	Description string   `json:"description,omitempty"`
+	Receipt     *Receipt `json:"receipt,omitempty"`
+}
+
+// Refund is a YooKassa refund object. Its ID is distinct from the refunded payment's id and is what
+// the ledger records as the refund's idempotency key.
+type Refund struct {
+	ID        string `json:"id"`
+	Status    string `json:"status"`
+	PaymentID string `json:"payment_id"`
+	Amount    Amount `json:"amount"`
+}
+
+// ErrUnconfigured is returned when a call is attempted on a shop with no credentials.
+var ErrUnconfigured = errors.New("yookassa: shop is not configured")
+
+// APIError is a non-2xx answer from the API. Description and Parameter come from YooKassa's error
+// object and name the offending field, which is what makes a malformed receipt diagnosable.
+type APIError struct {
+	StatusCode  int    `json:"-"`
+	Type        string `json:"type"`
+	ID          string `json:"id"`
+	Code        string `json:"code"`
+	Description string `json:"description"`
+	Parameter   string `json:"parameter"`
+	RetryAfter  int    `json:"retry_after"`
+}
+
+// Error renders the status together with YooKassa's own description, including the offending
+// parameter when the API named one.
+func (e *APIError) Error() string {
+	msg := e.Description
+	if msg == "" {
+		msg = e.Code
+	}
+	if e.Parameter != "" {
+		return fmt.Sprintf("yookassa: http %d: %s (parameter %s)", e.StatusCode, msg, e.Parameter)
+	}
+	return fmt.Sprintf("yookassa: http %d: %s", e.StatusCode, msg)
+}
+
+// Retryable reports whether repeating the call could succeed. A 5xx or a 429 is transient; a 4xx is
+// a permanent rejection of this request. Callers use it to decide whether to ask the provider to
+// redeliver a notification or to accept it as durably handled.
+func (e *APIError) Retryable() bool {
+	return e.StatusCode >= 500 || e.StatusCode == http.StatusTooManyRequests
+}
+
+// Configured reports whether the shop has credentials to call the API with.
+func (c Config) Configured() bool { return c.ShopID != "" && c.SecretKey != "" }
+
+// CreatePayment opens a payment for the order and returns the created object, whose
+// Confirmation.ConfirmationURL is the page the customer must be sent to. idempotenceKey makes the
+// call safe to retry — YooKassa replays the original result for 24 hours — so callers pass the order
+// id and never mint a second payment for the same order.
+func (c Config) CreatePayment(ctx context.Context, req PaymentRequest, idempotenceKey string) (Payment, error) {
+	var out Payment
+	err := c.do(ctx, http.MethodPost, "/payments", req, idempotenceKey, &out)
+	return out, err
+}
+
+// GetPayment re-reads a payment by id. This is the authenticity check for the whole rail: YooKassa
+// notifications are unsigned, so only the object returned here may be acted on.
+func (c Config) GetPayment(ctx context.Context, paymentID string) (Payment, error) {
+	var out Payment
+	err := c.do(ctx, http.MethodGet, "/payments/"+url.PathEscape(paymentID), nil, "", &out)
+	return out, err
+}
+
+// CreateRefund returns money for a succeeded payment and reports the created refund. idempotenceKey
+// guards against a double refund on a retry; callers pass the order id.
+func (c Config) CreateRefund(ctx context.Context, req RefundRequest, idempotenceKey string) (Refund, error) {
+	var out Refund
+	err := c.do(ctx, http.MethodPost, "/refunds", req, idempotenceKey, &out)
+	return out, err
+}
+
+// do performs one authenticated API call and decodes the result into out. A non-2xx answer is
+// returned as an *APIError carrying YooKassa's own error object when the body holds one.
+func (c Config) do(ctx context.Context, method, path string, body any, idempotenceKey string, out any) error {
+	if !c.Configured() {
+		return ErrUnconfigured
+	}
+	var payload io.Reader
+	if body != nil {
+		buf, err := json.Marshal(body)
+		if err != nil {
+			return fmt.Errorf("yookassa: encode %s %s: %w", method, path, err)
+		}
+		payload = bytes.NewReader(buf)
+	}
+	req, err := http.NewRequestWithContext(ctx, method, c.endpoint()+path, payload)
+	if err != nil {
+		return fmt.Errorf("yookassa: build %s %s: %w", method, path, err)
+	}
+	req.SetBasicAuth(c.ShopID, c.SecretKey)
+	req.Header.Set("Accept", "application/json")
+	if body != nil {
+		req.Header.Set("Content-Type", "application/json")
+	}
+	if idempotenceKey != "" {
+		req.Header.Set("Idempotence-Key", idempotenceKey)
+	}
+	resp, err := apiClient.Do(req)
+	if err != nil {
+		return fmt.Errorf("yookassa: %s %s: %w", method, path, err)
+	}
+	defer resp.Body.Close()
+	raw, err := io.ReadAll(io.LimitReader(resp.Body, maxResponseBytes))
+	if err != nil {
+		return fmt.Errorf("yookassa: read %s %s: %w", method, path, err)
+	}
+	if resp.StatusCode < 200 || resp.StatusCode > 299 {
+		apiErr := &APIError{StatusCode: resp.StatusCode}
+		// The body is YooKassa's error object on a handled fault and something else entirely on an
+		// edge failure; either way the status alone is enough to classify the error.
+		_ = json.Unmarshal(raw, apiErr)
+		return apiErr
+	}
+	if err := json.Unmarshal(raw, out); err != nil {
+		return fmt.Errorf("yookassa: decode %s %s: %w", method, path, err)
+	}
+	return nil
+}
+
+// endpoint returns the API root for this shop, without a trailing slash.
+func (c Config) endpoint() string {
+	if c.BaseURL == "" {
+		return DefaultBaseURL
+	}
+	return strings.TrimSuffix(c.BaseURL, "/")
+}

backend/internal/yookassa/yookassa_test.go

@@ -0,0 +1,225 @@
+package yookassa
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+)
+
+// capture records what the fake API received, so a test can assert on the request the client built.
+type capture struct {
+	method         string
+	path           string
+	authUser       string
+	authPass       string
+	idempotenceKey string
+	body           map[string]any
+}
+
+// fakeAPI serves one canned response and records the request. It returns a Config already pointed at
+// it, which is how every API-shaped test drives the client without touching the network.
+func fakeAPI(t *testing.T, status int, response string) (Config, *capture) {
+	t.Helper()
+	got := &capture{}
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		got.method = r.Method
+		got.path = r.URL.Path
+		got.authUser, got.authPass, _ = r.BasicAuth()
+		got.idempotenceKey = r.Header.Get("Idempotence-Key")
+		if raw, _ := io.ReadAll(r.Body); len(raw) > 0 {
+			_ = json.Unmarshal(raw, &got.body)
+		}
+		w.Header().Set("Content-Type", "application/json")
+		w.WriteHeader(status)
+		_, _ = io.WriteString(w, response)
+	}))
+	t.Cleanup(srv.Close)
+	return Config{ShopID: "100500", SecretKey: "secret", BaseURL: srv.URL}, got
+}
+
+func TestCreatePaymentBuildsTheRequest(t *testing.T) {
+	cfg, got := fakeAPI(t, http.StatusOK, `{
+		"id":"23d93cac-000f-5000-8000-126628f15141","status":"pending","paid":false,"test":false,
+		"amount":{"value":"149.00","currency":"RUB"},
+		"confirmation":{"type":"redirect","confirmation_url":"https://yoomoney.ru/pay/abc"},
+		"metadata":{"order_id":"0197-order"}}`)
+
+	amount := Amount{Value: "149.00", Currency: "RUB"}
+	p, err := cfg.CreatePayment(context.Background(), PaymentRequest{
+		Amount:       amount,
+		Capture:      true,
+		Confirmation: Confirmation{Type: ConfirmationRedirect, ReturnURL: "https://example.test/pay/yookassa/return"},
+		Description:  "10 chips",
+		Metadata:     map[string]string{MetadataOrderID: "0197-order"},
+		Receipt:      SingleItemReceipt("buyer@example.test", "10 chips", amount, VatCodeNone),
+	}, "0197-order")
+	if err != nil {
+		t.Fatalf("create payment: %v", err)
+	}
+
+	if got.method != http.MethodPost || got.path != "/payments" {
+		t.Errorf("request = %s %s, want POST /payments", got.method, got.path)
+	}
+	if got.authUser != "100500" || got.authPass != "secret" {
+		t.Errorf("basic auth = %q:%q, want the shop id and secret key", got.authUser, got.authPass)
+	}
+	// The idempotence key is what makes a retried create return the original payment instead of
+	// minting a second one for the same order.
+	if got.idempotenceKey != "0197-order" {
+		t.Errorf("Idempotence-Key = %q, want the order id", got.idempotenceKey)
+	}
+	if got.body["capture"] != true {
+		t.Errorf("capture = %v, want true (single-stage payment)", got.body["capture"])
+	}
+	conf, _ := got.body["confirmation"].(map[string]any)
+	if conf["type"] != ConfirmationRedirect || conf["return_url"] != "https://example.test/pay/yookassa/return" {
+		t.Errorf("confirmation = %v, want a redirect with the return url", conf)
+	}
+	meta, _ := got.body["metadata"].(map[string]any)
+	if meta[MetadataOrderID] != "0197-order" {
+		t.Errorf("metadata = %v, want the order id threaded through", meta)
+	}
+	receipt, _ := got.body["receipt"].(map[string]any)
+	customer, _ := receipt["customer"].(map[string]any)
+	if customer["email"] != "buyer@example.test" {
+		t.Errorf("receipt customer = %v, want the buyer email", customer)
+	}
+	items, _ := receipt["items"].([]any)
+	if len(items) != 1 {
+		t.Fatalf("receipt items = %d, want 1", len(items))
+	}
+	item, _ := items[0].(map[string]any)
+	if item["vat_code"] != float64(VatCodeNone) || item["payment_subject"] != PaymentSubjectService || item["payment_mode"] != PaymentModeFullPayment {
+		t.Errorf("receipt item fiscal attributes = %v", item)
+	}
+
+	if p.Confirmation.ConfirmationURL != "https://yoomoney.ru/pay/abc" {
+		t.Errorf("confirmation url = %q, want the hosted payment page", p.Confirmation.ConfirmationURL)
+	}
+	if p.OrderID() != "0197-order" {
+		t.Errorf("OrderID() = %q, want the order the payment funds", p.OrderID())
+	}
+}
+
+func TestGetPaymentReadsTheObject(t *testing.T) {
+	cfg, got := fakeAPI(t, http.StatusOK, `{
+		"id":"pay-1","status":"succeeded","paid":true,"test":true,
+		"amount":{"value":"149.00","currency":"RUB"},
+		"recipient":{"account_id":"100500","gateway_id":"100700"},
+		"metadata":{"order_id":"0197-order"}}`)
+
+	p, err := cfg.GetPayment(context.Background(), "pay-1")
+	if err != nil {
+		t.Fatalf("get payment: %v", err)
+	}
+	if got.method != http.MethodGet || got.path != "/payments/pay-1" {
+		t.Errorf("request = %s %s, want GET /payments/pay-1", got.method, got.path)
+	}
+	// A read is idempotent by nature, so no key is sent.
+	if got.idempotenceKey != "" {
+		t.Errorf("Idempotence-Key = %q, want none on a GET", got.idempotenceKey)
+	}
+	if p.Status != StatusSucceeded || !p.Paid {
+		t.Errorf("payment = %s paid=%v, want succeeded and paid", p.Status, p.Paid)
+	}
+	if !p.Test {
+		t.Error("Test = false, want true — a test-shop payment must be distinguishable from a live one")
+	}
+	if p.Recipient.AccountID != "100500" {
+		t.Errorf("recipient.account_id = %q, want the shop id", p.Recipient.AccountID)
+	}
+}
+
+func TestCreateRefundBuildsTheRequest(t *testing.T) {
+	cfg, got := fakeAPI(t, http.StatusOK, `{
+		"id":"refund-1","status":"succeeded","payment_id":"pay-1",
+		"amount":{"value":"149.00","currency":"RUB"}}`)
+
+	amount := Amount{Value: "149.00", Currency: "RUB"}
+	r, err := cfg.CreateRefund(context.Background(), RefundRequest{
+		PaymentID: "pay-1",
+		Amount:    amount,
+		Receipt:   SingleItemReceipt("buyer@example.test", "10 chips", amount, VatCodeNone),
+	}, "0197-order")
+	if err != nil {
+		t.Fatalf("create refund: %v", err)
+	}
+	if got.method != http.MethodPost || got.path != "/refunds" {
+		t.Errorf("request = %s %s, want POST /refunds", got.method, got.path)
+	}
+	if got.idempotenceKey != "0197-order" {
+		t.Errorf("Idempotence-Key = %q, want the order id (guards a double refund)", got.idempotenceKey)
+	}
+	if got.body["payment_id"] != "pay-1" {
+		t.Errorf("payment_id = %v, want the refunded payment", got.body["payment_id"])
+	}
+	if _, ok := got.body["receipt"]; !ok {
+		t.Error("refund carries no receipt — a refund receipt is required under «Чеки от ЮKassa»")
+	}
+	// The refund id is distinct from the payment id: the ledger keys the refund row on it, so the
+	// fund and refund rows can coexist under the same partial-unique index.
+	if r.ID != "refund-1" || r.PaymentID != "pay-1" {
+		t.Errorf("refund = %+v, want id refund-1 for payment pay-1", r)
+	}
+}
+
+func TestAPIErrorClassifiesRetryability(t *testing.T) {
+	cfg, _ := fakeAPI(t, http.StatusBadRequest,
+		`{"type":"error","id":"err-1","code":"invalid_request","description":"Receipt item is invalid","parameter":"receipt.items"}`)
+
+	_, err := cfg.GetPayment(context.Background(), "pay-1")
+	var apiErr *APIError
+	if !errors.As(err, &apiErr) {
+		t.Fatalf("error = %v, want an *APIError", err)
+	}
+	if apiErr.StatusCode != http.StatusBadRequest {
+		t.Errorf("status = %d, want 400", apiErr.StatusCode)
+	}
+	// The offending parameter is what makes a malformed receipt diagnosable rather than a mystery.
+	if !strings.Contains(apiErr.Error(), "receipt.items") {
+		t.Errorf("error text %q does not name the offending parameter", apiErr.Error())
+	}
+	if apiErr.Retryable() {
+		t.Error("a 400 reported as retryable; a permanent rejection must not be re-delivered")
+	}
+
+	for _, status := range []int{http.StatusTooManyRequests, http.StatusInternalServerError} {
+		cfg, _ := fakeAPI(t, status, `{"type":"error","description":"try later"}`)
+		_, err := cfg.GetPayment(context.Background(), "pay-1")
+		var e *APIError
+		if !errors.As(err, &e) || !e.Retryable() {
+			t.Errorf("status %d: error = %v, want a retryable *APIError", status, err)
+		}
+	}
+}
+
+func TestUnconfiguredShopMakesNoCall(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(http.ResponseWriter, *http.Request) {
+		t.Error("an unconfigured shop reached the API")
+	}))
+	t.Cleanup(srv.Close)
+
+	for name, cfg := range map[string]Config{
+		"no credentials": {BaseURL: srv.URL},
+		"no secret key":  {ShopID: "100500", BaseURL: srv.URL},
+		"no shop id":     {SecretKey: "secret", BaseURL: srv.URL},
+	} {
+		if _, err := cfg.GetPayment(context.Background(), "pay-1"); !errors.Is(err, ErrUnconfigured) {
+			t.Errorf("%s: error = %v, want ErrUnconfigured", name, err)
+		}
+	}
+}
+
+func TestEndpointDefaultsToTheProductionAPI(t *testing.T) {
+	if got := (Config{}).endpoint(); got != DefaultBaseURL {
+		t.Errorf("endpoint = %q, want %q", got, DefaultBaseURL)
+	}
+	if got := (Config{BaseURL: "https://api.test/v3/"}).endpoint(); got != "https://api.test/v3" {
+		t.Errorf("endpoint = %q, want the trailing slash trimmed", got)
+	}
+}

deploy/.env.example

@@ -132,28 +132,30 @@ GATEWAY_VK_APP_SECRET=
 # come from VITE_VK_APP_ID / VITE_VK_ID_REDIRECT_URL above. All three empty disables link.vk.*.
 GATEWAY_VK_ID_CLIENT_SECRET=
 
-# --- Payments: Robokassa (direct RUB rail) ----------------------------------
-# The shop's merchant login + the two pass phrases (Password1 signs the launch request,
-# Password2 signs/verifies the Result callback). An empty login leaves the direct rail off.
-# ROBOKASSA_TEST=1 runs test payments against the shop's TEST pass phrases (no real money);
-# empty/0 is live. Mapped in compose to BACKEND_ROBOKASSA_*; Gitea TEST_/PROD_ secrets, with
-# PROD_BACKEND_ROBOKASSA_TEST a variable so go-live is a flag flip, not a secret redeploy.
-ROBOKASSA_MERCHANT_LOGIN=
-ROBOKASSA_PASSWORD1=
-ROBOKASSA_PASSWORD2=
-ROBOKASSA_TEST=
-# Multi-shop direct rail (D42): the vars above seed the "web" channel; add per-channel shops here.
-# ROBOKASSA_WEB_* overrides the web shop; ROBOKASSA_ANDROID_* adds the android (RuStore) shop. Each
-# credits the one direct wallet; an empty login drops that channel (routing falls back to web). The
-# Robokassa cabinet points each shop's Result URL at /pay/robokassa/result/web and .../android.
-ROBOKASSA_WEB_MERCHANT_LOGIN=
-ROBOKASSA_WEB_PASSWORD1=
-ROBOKASSA_WEB_PASSWORD2=
-ROBOKASSA_WEB_TEST=
-ROBOKASSA_ANDROID_MERCHANT_LOGIN=
-ROBOKASSA_ANDROID_PASSWORD1=
-ROBOKASSA_ANDROID_PASSWORD2=
-ROBOKASSA_ANDROID_TEST=
+# --- Payments: YooKassa (direct RUB rail) ------------------------------------
+# One merchant shop per channel (D42): the shop id (Настройки — Магазин, field shopId) and the
+# secret key (Интеграция — Ключи API). Each shop credits the one direct wallet; a shop missing
+# either credential drops that channel (order routing falls back to web), and no shop at all
+# leaves the direct rail off. YOOKASSA_*_TEST=1 marks a TEST shop, which makes the intake refuse
+# to credit a live payment against it (and a test payment against a live shop).
+# Mapped in compose to BACKEND_YOOKASSA_*; Gitea TEST_/PROD_ secrets.
+# Set each shop's notification URL in its cabinet (Интеграция — HTTP-уведомления) to
+# ${PUBLIC_BASE_URL}/pay/yookassa/notify, events payment.succeeded + payment.canceled.
+YOOKASSA_WEB_SHOP_ID=
+YOOKASSA_WEB_SECRET_KEY=
+YOOKASSA_WEB_TEST=
+# The android (RuStore) shop — add when that channel gets its own merchant account.
+YOOKASSA_ANDROID_SHOP_ID=
+YOOKASSA_ANDROID_SECRET_KEY=
+YOOKASSA_ANDROID_TEST=
+# VAT rate code on every fiscal receipt line (54-ФЗ tag 1199): 1 = «Без НДС» (УСН/ПСН), 4 = 20%,
+# 11 = 22%. A Gitea VARIABLE, not a secret, so a rate change is a variable edit + redeploy.
+YOOKASSA_VAT_CODE=1
+#
+# Robokassa (the retired direct rail) is deliberately absent here: no deployment sets its
+# credentials, which is what keeps it dormant. The backend still reads BACKEND_ROBOKASSA_* and
+# falls the direct rail back to it if they are ever set again — see
+# backend/internal/robokassa/README.md for the full variable set and how to revive the rail.
 
 # --- Gateway anti-abuse ------------------------------------------------------
 # Planted honeytoken bearer value: any request presenting it is flagged — a 24h IP ban

deploy/README.md

@@ -76,10 +76,10 @@ compose binds from this directory.
 | `GM_BASICAUTH_HASH` | secret | bcrypt hash gating `/_gm` (admin console + Grafana). Generate with `docker run --rm caddy:2-alpine caddy hash-password --plaintext '<pw>'`. |
 | `TELEGRAM_MINIAPP_URL` | derived | The Mini App URL the bot hands out in deep links / buttons. The deploy derives `PUBLIC_BASE_URL + /telegram/`; set it directly only for a local run (compose still `:?`-requires it). |
 | `EXPORT_SIGN_KEY` | secret | HMAC key signing the public finished-game export download URLs (`/dl/*`). Generate with `openssl rand -base64 32`. |
-| `BACKEND_ROBOKASSA_MERCHANT_LOGIN` | secret | Robokassa shop login for the direct RUB rail. Empty leaves the rail off. |
-| `BACKEND_ROBOKASSA_PASSWORD1` / `…_PASSWORD2` | secret | Robokassa pass phrases: Password1 signs the launch request, Password2 signs/verifies the Result callback. Use the shop's **test** pair while `…_ROBOKASSA_TEST=1`, the **live** pair for real money. (Password3 — Robokassa's JWT-invoice API — is unused.) |
-| `BACKEND_ROBOKASSA_TEST` | **variable** | `1` runs test payments against the test pass phrases (no real money); empty/`0` is live. A variable, not a secret, so go-live is a flag flip + redeploy, not a secret rotation. |
-| `BACKEND_ROBOKASSA_{WEB,ANDROID}_{MERCHANT_LOGIN,PASSWORD1,PASSWORD2,TEST}` | secret / variable | Multi-shop direct rail (D42): per-channel Robokassa shops. The legacy `BACKEND_ROBOKASSA_*` seeds the **web** shop; `…_WEB_*` overrides it, `…_ANDROID_*` adds the **android** (RuStore) shop. Each credits the one `direct` wallet; the cabinet Result URL per shop is `/pay/robokassa/result/{web,android}`. Empty login ⇒ that channel unconfigured (order routing falls back to the web shop). |
+| `BACKEND_YOOKASSA_{WEB,ANDROID}_SHOP_ID` | secret | YooKassa shop id for that channel of the direct RUB rail (cabinet: **Настройки — Магазин**, field `shopId`). Empty ⇒ that channel is unconfigured and order routing falls back to the **web** shop; no channel configured at all leaves the rail off. |
+| `BACKEND_YOOKASSA_{WEB,ANDROID}_SECRET_KEY` | secret | That shop's API secret key (cabinet: **Интеграция — Ключи API**). It is the password half of the HTTP Basic credentials on every API call. A shop id without a secret key is ignored. |
+| `BACKEND_YOOKASSA_{WEB,ANDROID}_TEST` | **variable** | `1` marks the credentials as a **test shop**: the intake then refuses to credit anything but a test payment (and a live shop refuses a test one). A variable, not a secret, so switching a contour between a test and a live shop is a flag flip + redeploy. |
+| `BACKEND_YOOKASSA_VAT_CODE` | **variable** | VAT rate code stamped on every fiscal receipt line (54-ФЗ tag 1199): `1` = «Без НДС» (УСН/ПСН), `4` = 20%, `11` = 22%. Defaults to `1`. A variable so a rate change needs no code change. **Confirm it with the accountant before the first real payment** — a wrong rate produces wrong receipts, not a failed payment, so it fails silently. |
 
 **Plus the bot token** — `TELEGRAM_BOT_TOKEN` (secret), shared by the validator (HMAC
 secret) and the bot (Bot API). It defaults to empty in compose, but both **fail at

deploy/docker-compose.yml

@@ -164,25 +164,21 @@ services:
       # recipient(s) (comma-separated allowed). Both empty disables the alert worker.
       BACKEND_SMTP_ADMIN_FROM: ${SMTP_RELAY_ADMIN_FROM:-}
       BACKEND_ADMIN_EMAIL: ${ADMIN_EMAIL:-}
-      # Direct-rail (Robokassa) payment intake: the merchant login + Password1/Password2 and the
-      # test-mode flag (deploy env: TEST_/PROD_BACKEND_ROBOKASSA_*). An empty login leaves the
-      # direct order and Result-callback endpoints unregistered (the rail is off).
-      BACKEND_ROBOKASSA_MERCHANT_LOGIN: ${ROBOKASSA_MERCHANT_LOGIN:-}
-      BACKEND_ROBOKASSA_PASSWORD1: ${ROBOKASSA_PASSWORD1:-}
-      BACKEND_ROBOKASSA_PASSWORD2: ${ROBOKASSA_PASSWORD2:-}
-      BACKEND_ROBOKASSA_TEST: ${ROBOKASSA_TEST:-}
-      # Per-channel shops for the multi-shop direct rail (D42): the legacy ROBOKASSA_* above seeds
-      # the "web" channel; ROBOKASSA_WEB_* overrides it and ROBOKASSA_ANDROID_* adds the android
-      # shop. Each shop credits the one direct wallet; an empty login drops that channel (order
-      # routing falls back to the web shop). Result URLs: /pay/robokassa/result/{web,android}.
-      BACKEND_ROBOKASSA_WEB_MERCHANT_LOGIN: ${ROBOKASSA_WEB_MERCHANT_LOGIN:-}
-      BACKEND_ROBOKASSA_WEB_PASSWORD1: ${ROBOKASSA_WEB_PASSWORD1:-}
-      BACKEND_ROBOKASSA_WEB_PASSWORD2: ${ROBOKASSA_WEB_PASSWORD2:-}
-      BACKEND_ROBOKASSA_WEB_TEST: ${ROBOKASSA_WEB_TEST:-}
-      BACKEND_ROBOKASSA_ANDROID_MERCHANT_LOGIN: ${ROBOKASSA_ANDROID_MERCHANT_LOGIN:-}
-      BACKEND_ROBOKASSA_ANDROID_PASSWORD1: ${ROBOKASSA_ANDROID_PASSWORD1:-}
-      BACKEND_ROBOKASSA_ANDROID_PASSWORD2: ${ROBOKASSA_ANDROID_PASSWORD2:-}
-      BACKEND_ROBOKASSA_ANDROID_TEST: ${ROBOKASSA_ANDROID_TEST:-}
+      # Direct-rail (YooKassa) payment intake, one merchant shop per channel (D42): the shop id +
+      # secret key and a flag marking a test shop (deploy env: TEST_/PROD_BACKEND_YOOKASSA_*).
+      # Each shop credits the one direct wallet; a shop missing either credential drops that
+      # channel (order routing falls back to the web shop), and no shop at all leaves the direct
+      # order and notification endpoints unregistered. Notification URL (set per shop in the
+      # YooKassa cabinet): ${PUBLIC_BASE_URL}/pay/yookassa/notify.
+      BACKEND_YOOKASSA_WEB_SHOP_ID: ${YOOKASSA_WEB_SHOP_ID:-}
+      BACKEND_YOOKASSA_WEB_SECRET_KEY: ${YOOKASSA_WEB_SECRET_KEY:-}
+      BACKEND_YOOKASSA_WEB_TEST: ${YOOKASSA_WEB_TEST:-}
+      BACKEND_YOOKASSA_ANDROID_SHOP_ID: ${YOOKASSA_ANDROID_SHOP_ID:-}
+      BACKEND_YOOKASSA_ANDROID_SECRET_KEY: ${YOOKASSA_ANDROID_SECRET_KEY:-}
+      BACKEND_YOOKASSA_ANDROID_TEST: ${YOOKASSA_ANDROID_TEST:-}
+      # VAT rate code stamped on every fiscal receipt line (54-ФЗ tag 1199). 1 = «Без НДС» (УСН/ПСН).
+      # A deploy variable, not a secret, so a rate change is a variable edit + redeploy.
+      BACKEND_YOOKASSA_VAT_CODE: ${YOOKASSA_VAT_CODE:-1}
     # The dictionary lives on a named volume seeded from the image on first boot
     # (the image's /opt/dawg is owned by the nonroot UID, which the fresh volume
     # inherits). The admin console writes new version subdirectories here, and the

deploy/write-prod-env.sh

@@ -54,10 +54,13 @@ export GATEWAY_RECOMMENDED_CLIENT_VERSION='$GATEWAY_RECOMMENDED_CLIENT_VERSION'
 export TELEGRAM_BOT_TOKEN='$TELEGRAM_BOT_TOKEN'
 export TELEGRAM_MINIAPP_URL='$TELEGRAM_MINIAPP_URL'
 export GATEWAY_VK_APP_SECRET='$GATEWAY_VK_APP_SECRET'
-export ROBOKASSA_MERCHANT_LOGIN='$ROBOKASSA_MERCHANT_LOGIN'
-export ROBOKASSA_PASSWORD1='$ROBOKASSA_PASSWORD1'
-export ROBOKASSA_PASSWORD2='$ROBOKASSA_PASSWORD2'
-export ROBOKASSA_TEST='$ROBOKASSA_TEST'
+export YOOKASSA_WEB_SHOP_ID='$YOOKASSA_WEB_SHOP_ID'
+export YOOKASSA_WEB_SECRET_KEY='$YOOKASSA_WEB_SECRET_KEY'
+export YOOKASSA_WEB_TEST='$YOOKASSA_WEB_TEST'
+export YOOKASSA_ANDROID_SHOP_ID='$YOOKASSA_ANDROID_SHOP_ID'
+export YOOKASSA_ANDROID_SECRET_KEY='$YOOKASSA_ANDROID_SECRET_KEY'
+export YOOKASSA_ANDROID_TEST='$YOOKASSA_ANDROID_TEST'
+export YOOKASSA_VAT_CODE='${YOOKASSA_VAT_CODE:-1}'
 export VITE_VK_APP_ID='$VITE_VK_APP_ID'
 export VITE_VK_ID_REDIRECT_URL='$VITE_VK_ID_REDIRECT_URL'
 export GATEWAY_VK_ID_CLIENT_SECRET='$GATEWAY_VK_ID_CLIENT_SECRET'

docs/PAYMENTS.md

@@ -23,7 +23,7 @@ The game earns through two orthogonal channels:
 The currency is **two-tier**:
 
 ```
-money (VK Votes / TG Stars / RUB via Robokassa)  ─┐
+money (VK Votes / TG Stars / RUB via YooKassa)   ─┐
                                                   ├─►  Фишки (chips)  ──►  values
 rewarded ad view                                 ─┘                         (no-ads, hints,
                                                                              tournament fee)
@@ -46,7 +46,7 @@ The chip balance is **segmented by `source`** — the platform where the chips w
 |------------|----------------------------------|
 | `vk`       | VK Votes purchase, VK rewarded ad |
 | `telegram` | TG Stars purchase                |
-| `direct`   | Robokassa purchase (web / native)|
+| `direct`   | YooKassa purchase (web / native) |
 
 A single account holds all three segments simultaneously: `balance = (account_id, source)`,
 up to three rows — a row is materialised lazily on the segment's first funding, and an absent
@@ -54,17 +54,27 @@ segment reads as zero. Segmentation is **not** per-identity — see §6.
 
 Why segmented, not one pooled balance: store rules forbid activating value that was paid
 for outside the store's own cash desk. Chips funded inside VK (Votes) may only be spent in
-the VK context; Stars only inside Telegram; Robokassa-funded (`direct`) chips only outside
+the VK context; Stars only inside Telegram; YooKassa-funded (`direct`) chips only outside
 the stores. See §4.
 
-**Multi-shop direct rail (D42).** The `direct` rail routes to one Robokassa **merchant shop per
+**Multi-shop direct rail (D42).** The `direct` rail routes to one YooKassa **merchant shop per
 channel** — `web` and `android` (RuStore), `ios` later — chosen by the trusted `X-Platform` subtype;
 every shop credits the one `direct` wallet (no per-channel wallet). This is merchant-account
-separation for accounting / receipts only: the order records its `shop` (shown in the admin report),
-and each shop's Result callback is verified by its own Password2 at `/pay/robokassa/result/<channel>`.
+separation for accounting / receipts only: the order records its `shop` (shown in the admin report).
+All shops share one notification endpoint, `/pay/yookassa/notify`; an incoming notification is
+attributed to a shop by the shop id the payment reports (`recipient.account_id`), falling back to the
+channel recorded on the order, and that shop's credentials perform the confirming read (§9).
 Standalone apps (Android/iOS) sign in by email only, so a direct purchase always has the D36 email
-anchor (D43). Fiscalization (54-ФЗ via the Robokassa cabinet under one ИП) is a single source
-regardless of the number of shops (D41).
+anchor (D43), which is also where the fiscal receipt is delivered. Fiscalization (54-ФЗ under one ИП)
+is a single source regardless of the number of shops (D41).
+
+**Robokassa is retired, not deleted (D47).** It settled the `direct` rail before YooKassa. Its code,
+tests and wiring stay in the tree and the rail falls back to it when no YooKassa shop is configured,
+so reviving it is a credentials change rather than a code change; no deployment sets those
+credentials today. `backend/internal/robokassa/README.md` records the retired variables, the cabinet
+configuration and the revival steps. Ledger rows written while it was live keep
+`provider = 'robokassa'` — that literal is load-bearing for the idempotency index and is never
+renamed or reused.
 
 **Payment availability kill switch (D45/D46).** An operator can disable purchases on a rail/channel
 (`direct:web` / `direct:android` / `vk` / `telegram`) or for one account, live from `/_gm`, and the
@@ -224,20 +234,47 @@ never the source of truth.
 
 ## 9. Payment intake
 
-**Server callback only.** Chips are credited solely on a **verified** (signature/HMAC)
-provider callback — Robokassa webhook / TG `successful_payment` / VK callback. A client "I
-paid" is ignored.
+**Server callback only.** Chips are credited solely on a **verified** provider callback —
+YooKassa notification / TG `successful_payment` / VK callback. A client "I paid" is ignored. What
+"verified" means differs by rail: VK and Telegram sign their callbacks, and **YooKassa does not**
+(D48) — see the confirming read below.
 
 **Single writer.** One payments domain is the only writer of the ledger. Public webhooks
-(Robokassa/VK) terminate at the edge (Caddy/gateway) and proxy into payments; TG
+(YooKassa/VK) terminate at the edge (Caddy/gateway) and proxy into payments; TG
 `successful_payment` reaches the bot, which forwards into payments. One place credits and
 dedupes.
 
 **Order-flow.** The server pre-creates an `order(pending)` with account / platform / pack /
-expected amount / origin. The `order_id` is threaded to the provider (Robokassa `InvId` / TG
-`invoice_payload` / VK `item` — confirm the exact VK field at integration). The callback
-matches by `order_id` (never by amount, so equal-amount collisions cannot happen), verifies
-the amount, credits, marks `paid`. **Idempotency:** dedup by `(provider, provider_payment_id)`.
+expected amount / origin. The `order_id` is threaded to the provider (YooKassa `metadata.order_id` /
+TG `invoice_payload` / VK `item`). The callback matches by `order_id` (never by amount, so
+equal-amount collisions cannot happen), verifies the amount, credits, marks `paid`.
+**Idempotency:** dedup by `(provider, provider_payment_id)`.
+
+**Direct rail (YooKassa).** Opening a purchase is an outbound API call: the server creates the
+payment (`POST /v3/payments`, `capture: true`, redirect confirmation, the order id as both the
+`Idempotence-Key` and `metadata.order_id`, plus the fiscal receipt of §12) and sends the customer to
+the returned `confirmation_url`. The provider's payment id is recorded on the order straight away,
+which is what later lets the order be re-checked and refunded. The browser return page
+(`/pay/yookassa/return`) is cosmetic: the credit never rides a redirect.
+
+**The notification is a hint, never evidence (D48).** YooKassa does not sign notifications, so
+nothing in the body may be acted on. It only names a payment, which the server then re-reads with
+`GET /v3/payments/{id}`; only that answer is trusted. Two guards ride on it: the payment's metadata
+must name the order being credited, and its `test` flag must match the shop's, so a test-shop payment
+can never credit real chips (nor a live payment be credited against test credentials). As defence in
+depth — and to stop a forger turning each fabricated notification into an outbound call of ours — the
+sender address is first checked against YooKassa's published ranges. The reply tells the provider
+whether to redeliver: 200 for anything durably decided, including a duplicate and a permanent
+rejection, and 5xx only for a transient failure (YooKassa redelivers for 24 hours).
+
+**Expiry-time reconciliation (D49).** No continuous polling. But a notification that is lost for good
+would leave the money taken and the chips unowed, silently, so the existing pending-order reaper asks
+the provider what became of each order that reached its expiry age carrying a payment id, and credits
+the ones that were in fact paid. One request per order over its whole life.
+
+**A declined payment is surfaced.** A YooKassa `payment.canceled` records a `failed` payment event,
+so the customer is told the attempt did not go through instead of watching a balance that never
+moves. An order simply abandoned records nothing — it just expires, invisibly.
 
 **Pending is invisible** to the user; it auto-expires on a timeout (~30 min, DB hygiene). A
 valid callback is **always** honoured, even on an expired order (`expired` ≠ cancellation —
@@ -266,10 +303,14 @@ an abandoned pending) is surfaced to the user; "payment succeeded" is a hook (em
 message).
 
 **Refunds.** ToS is **non-refundable** — we do not offer refunds to the user. Refunds are
-**admin-triggered** (the E7 console), since no rail pushes an unsolicited refund: Robokassa
-refunds run through its refund API / merchant cabinet (auto-polling a rail's refund status is a
-deferred worker, not worth it at low chargeback volume), VK refunds are handled by support, and
-Telegram Stars refunds are issued with `refundStarPayment`. All of them converge on one engine —
+**admin-triggered** (the E7 console), since no rail pushes an unsolicited refund. On the direct
+rail the console does the whole job in one click (D50): it calls YooKassa's refund API first
+(`POST /v3/refunds`, the order id as the `Idempotence-Key`, carrying the refund receipt of §12) and
+records the reversal only once the money has actually moved — a failed call records **nothing**, so
+the ledger can never claim a refund that did not happen. The recorded refund id is the provider's
+own, which keeps the ledger reconcilable against YooKassa's records. VK refunds are still handled by
+support and Telegram Stars refunds issued with `refundStarPayment`, both recorded by hand afterwards.
+All of them converge on one engine —
 the `Refund` method (`internal/payments`): it matches the paid order, appends a **refund** ledger
 row (idempotent on `(provider, provider_refund_id)` — the refund id is distinct from the fund's
 payment id, so the two rows coexist under the same partial-unique index), and **best-effort revokes
@@ -356,7 +397,15 @@ spends, grants, refunds, full history — as an extension of the existing user c
 
 Receipts are automatic **through the provider**, and differ by rail:
 
-- **Robokassa** (direct) — self-employed НПД receipt on payment.
+- **YooKassa** (direct) — a 54-ФЗ fiscal receipt through **«Чеки от ЮKassa»**: YooKassa owns the
+  cash register, the fiscal drive and the OFD contract, and files with the tax authority. Unlike the
+  retired rail's cabinet-side receipts, it registers one **only if the request carries it** (D51), so
+  every payment and every refund sends a `receipt`: one line (the pack title, quantity 1, the amount)
+  with the VAT rate code (54-ФЗ tag 1199, a deploy variable — `1` = «Без НДС» for УСН/ПСН), the
+  settlement subject `service` (tag 1212) and the settlement method `full_payment` (tag 1214).
+  Delivery is by email only, to the D36 confirmed anchor. `tax_system_code` is not sent — YooKassa
+  ignores it for this solution. A malformed receipt is an API error at payment creation, so it blocks
+  the purchase loudly rather than silently skipping the fiscal document.
 - **VK** — VK processes Votes through the tax authority itself; nothing to do.
 - **TG Stars** — no tax side (for a RU self-employed, Stars are not legally withdrawable = not
   НПД income; accepted, no receipt issued).
@@ -366,7 +415,7 @@ confirms the exact НПД scheme with a tax advisor.)
 
 ## 13. Distribution (native Android)
 
-- **RuStore** — Robokassa/external gate allowed (0%); native = clean `direct` context.
+- **RuStore** — an external payment gate is allowed (0%); native = clean `direct` context.
 - **Google Play** — direct purchases are **hidden**; the Wallet shows a stub ("install the
   RuStore build to make purchases"). Rewarded ads and spending already-earned chips still
   work. Confirm Google's current in-app-currency rules before the GP release.
@@ -407,4 +456,4 @@ prod (no purchase flow existed), so legacy values are zeroed.
 - **value / benefit** — what chips buy (no-ads, hints, tournament fee).
 - **gate** — the one-directional store-compliance rule (§4).
 - **ledger** — the append-only record of all money/value operations.
-- **rail** — a payment provider (Robokassa / VK Votes / TG Stars).
+- **rail** — a payment provider (YooKassa / VK Votes / TG Stars).

docs/PAYMENTS_DECISIONS_ru.md

@@ -281,6 +281,46 @@ web+PWA / native Android+iOS через Capacitor). Владелец (самоз
   (нет строки = default; снять = удалить строку). **`allow` обходит ТОЛЬКО ops-рубильник, НЕ
   security-гейты** (D36 email-якорь, VK-iOS-фриз, trusted-платформа, min-client-version) — те
   проверяются отдельно в CreateOrder.
+- **D47. Direct-рельс переезжает с Robokassa на ЮKassa; Robokassa консервируется, а не удаляется.**
+  Меняется merchant-отношение, не модель кошельков: сегмент `direct`, стенка трат, origin бенефитов,
+  мультимагазинность по каналу (D42) и `shop` в заказе (D44) — без изменений. Код Robokassa, её тесты
+  и проводка остаются в дереве, а direct-рельс **откатывается на неё**, если ни один магазин ЮKassa не
+  настроен, — значит возврат к Robokassa это смена кредов, а не правка кода. Переменные Robokassa
+  убраны из CI/compose/деплоя и записаны в `backend/internal/robokassa/README.md` вместе с
+  настройками кабинета и порядком возврата. Строки журнала с `provider = 'robokassa'` не трогаем:
+  литерал несущий для индекса идемпотентности. Telegram **не трогаем** — там реальными деньгами за
+  цифровые товары платить нельзя, рельс остаётся на Stars; префиксы переменных заводим на магазин
+  сразу, чтобы будущий магазин (например, android/RuStore) добавлялся аддитивно.
+- **D48. Уведомления ЮKassa не подписаны → подтверждающее чтение обязательно.** В отличие от
+  Robokassa (подпись Password2) и VK (подпись), ЮKassa **не подписывает** вебхуки. Поэтому тело
+  уведомления — только подсказка: оно называет платёж, который сервер перечитывает запросом
+  `GET /v3/payments/{id}`, и действует **исключительно** по ответу API. Дополнительно: метаданные
+  платежа должны называть тот самый заказ; флаг `test` платежа должен совпадать с флагом магазина
+  (платёж тестового магазина не начислит настоящие Фишки, и наоборот); адрес отправителя сверяется с
+  опубликованными диапазонами ЮKassa — эшелонированная защита, которая не даёт превратить каждое
+  фальшивое уведомление в наш исходящий запрос. Ответ провайдеру: 200 на всё окончательно решённое
+  (включая дубль и неустранимый отказ), 5xx только на временный сбой (ЮKassa повторяет 24 часа).
+- **D49. Сверка — одна проверка на истечении заказа, без постоянного опроса.** «Или» в документации
+  ЮKassa адресовано тем, кто не хочет вебхуки; у нас вебхуки основные. Но безвозвратно потерянное
+  уведомление оставило бы деньги списанными, а Фишки — не выданными, и молча. Поэтому существующий
+  жнец просроченных заказов перед списанием в `expired` спрашивает провайдера о судьбе каждого заказа,
+  дожившего до срока с идентификатором платежа, и начисляет реально оплаченные. Один запрос на заказ
+  за всю его жизнь; отдельный воркер не заводим.
+- **D50. Возвраты на direct-рельсе — через API ЮKassa, одним действием.** Кнопка возврата в `/_gm`
+  сперва двигает деньги (`POST /v3/refunds`, `Idempotence-Key` = идентификатор заказа, с чеком
+  возврата) и только потом пишет реверс в журнал; неудачный вызов не пишет **ничего** — журнал не
+  может заявить о возврате, которого не было. Записывается собственный refund-id провайдера (сверка с
+  данными ЮKassa). VK и TG Stars — как раньше: деньги руками, запись фактом.
+- **D51. Фискализация — «Чеки от ЮKassa», чек отправляем из кода.** Ревизия D41: у ЮKassa нет
+  кабинетного «обобщённого чека», как у Robokassa, — чек регистрируется **только если запрос его
+  несёт**, поэтому itemized-код, от которого отказались в D41, возвращается в объём. Каждый платёж и
+  возврат шлют `receipt`: одна позиция (название пакета, количество 1, сумма), код ставки НДС
+  (тег 1199), признак предмета расчёта `service` (тег 1212), признак способа расчёта `full_payment`
+  (тег 1214); доставка только на email — на подтверждённый якорь D36. Код ставки НДС — **переменная
+  деплоя** (дефолт `1` = «Без НДС» для УСН/ПСН): это единственный реквизит, который реально меняется
+  (с 1 января 2026 ставки выросли, появились коды 11/12), и менять его без релиза нужно; признаки
+  предмета и способа расчёта — константы в коде. `tax_system_code` не шлём: для «Чеков от ЮKassa»
+  провайдер его игнорирует.
 
 ## Заметки к оформлению документов
 
@@ -296,7 +336,7 @@ web+PWA / native Android+iOS через Capacitor). Владелец (самоз
   ведёт к пропускам. Текст — только для фиксации решённого и пояснений. Усилить
   feedback-память `prefer-interview-mode` после plan mode.
 
-## Все развилки закрыты (D1-D46)
+## Все развилки закрыты (D1-D51)
 
 Интервью завершено. Дальше — оформление документов и реализация по релизам.
 
@@ -307,6 +347,14 @@ web+PWA / native Android+iOS через Capacitor). Владелец (самоз
 рубильник платежей per-rail + локализованное сообщение + per-user override (этап E11). Фискализация
 (B4) — кабинетная на стороне Robokassa, itemized-код не делаем (решение владельца).
 
+**Дополнение 2026-07-28 (интервью с владельцем).** Direct-рельс переезжает на **ЮKassa**; добавлены
+D47-D51 — консервация Robokassa с откатом по кредам, подтверждающее чтение вместо подписи уведомления,
+сверка на истечении заказа, возвраты через API и фискализация через «Чеки от ЮKassa» с отправкой
+`receipt` из кода (ревизия D41, этап E12 в `PLAN.md`). Telegram из объёма исключён: реальными
+деньгами за цифровые товары в Mini App платить нельзя, рельс остаётся на Stars. Отдельно уточнено:
+у ЮKassa **есть** тестовый режим (отдельный тестовый магазин со своими креды и тестовыми картами),
+поэтому весь путь проверяется на тестовом контуре без реальных денег.
+
 ## План внедрения (черновик PLAN.md — «слоями»)
 
 Владелец выбрал слоёную стратегию: сначала вся механика без реальных денег (обкатка

docs/PAYMENTS_ru.md

@@ -23,7 +23,7 @@
 Валюта **двухуровневая**:
 
 ```
-деньги (Голоса VK / Stars TG / рубли через Robokassa)  ─┐
+деньги (Голоса VK / Stars TG / рубли через ЮKassa)  ─┐
                                                         ├─►  Фишки  ──►  ценности
 просмотр ролика за награду                             ─┘                (без рекламы,
                                                                           подсказки,
@@ -46,7 +46,7 @@
 |------------|------------------------------------|
 | `vk`       | Покупка за Голоса VK, ролик за награду в VK |
 | `telegram` | Покупка за Stars TG                |
-| `direct`   | Покупка через Robokassa (web / native) |
+| `direct`   | Покупка через ЮKassa (web / native) |
 
 Один аккаунт держит все три сегмента одновременно: `баланс = (account_id, source)`, до трёх
 записей — запись материализуется лениво при первом пополнении сегмента, отсутствующий сегмент
@@ -54,17 +54,27 @@
 
 Почему сегментировано, а не один общий баланс: правила сторов запрещают активировать
 ценность, оплаченную мимо их кассы. Фишки, пополненные внутри VK (Голоса), тратятся только
-в контексте VK; Stars — только внутри Telegram; Фишки от Robokassa (`direct`) — только вне
+в контексте VK; Stars — только внутри Telegram; Фишки от ЮKassa (`direct`) — только вне
 сторов. См. §4.
 
 **Мультимагазинный direct-рельс (D42).** Рельс `direct` маршрутизирует в отдельный магазин
-Robokassa **на канал** — `web` и `android` (RuStore), позже `ios` — по трастовому подтипу
+ЮKassa **на канал** — `web` и `android` (RuStore), позже `ios` — по трастовому подтипу
 `X-Platform`; каждый магазин зачисляет в единый кошелёк `direct` (отдельных кошельков на канал нет).
 Это разделение merchant-аккаунтов только для учёта / чеков: заказ хранит свой `shop` (виден в
-админ-отчёте), а Result-колбэк каждого магазина проверяется своим Password2 по
-`/pay/robokassa/result/<channel>`. В standalone-приложениях (Android/iOS) вход только по email, поэтому
-у direct-покупки всегда есть email-якорь D36 (D43). Фискализация (54-ФЗ через кабинет Robokassa под
-одним ИП) — один источник независимо от числа магазинов (D41).
+админ-отчёте). Точка приёма уведомлений у всех магазинов одна — `/pay/yookassa/notify`; входящее
+уведомление привязывается к магазину по идентификатору магазина, который сообщает сам платёж
+(`recipient.account_id`), с откатом на канал, записанный в заказе, и подтверждающее чтение (§9)
+выполняется кредами именно этого магазина. В standalone-приложениях (Android/iOS) вход только по
+email, поэтому у direct-покупки всегда есть email-якорь D36 (D43) — он же адрес доставки чека.
+Фискализация (54-ФЗ под одним ИП) — один источник независимо от числа магазинов (D41).
+
+**Robokassa законсервирована, но не удалена (D47).** До ЮKassa она обслуживала рельс `direct`. Код,
+тесты и проводка остаются в дереве, и рельс откатывается на неё, если ни один магазин ЮKassa не
+настроен, — поэтому возврат к ней это смена кредов, а не правка кода; сегодня эти креды не задаёт ни
+один контур. `backend/internal/robokassa/README.md` хранит список выведенных переменных, настройки
+кабинета и порядок возврата рельса. Строки журнала, записанные при её жизни, сохраняют
+`provider = 'robokassa'` — этот литерал несущий для индекса идемпотентности, его не переименовывают и
+не переиспользуют.
 
 **Рубильник платежей (D45/D46).** Оператор выключает покупки на рельсе/канале (`direct:web` /
 `direct:android` / `vk` / `telegram`) или для одного аккаунта, живьём из `/_gm`, и юзер на следующей
@@ -217,21 +227,48 @@ durable).
 
 ## 9. Приём платежей
 
-**Только серверный колбэк провайдера.** Фишки начисляются лишь по **проверенному**
-(подпись/HMAC) серверному колбэку — Robokassa webhook / TG `successful_payment` / VK
-callback. Клиентское «я оплатил» игнорируется.
+**Только серверный колбэк провайдера.** Фишки начисляются лишь по **проверенному** серверному
+колбэку — уведомление ЮKassa / TG `successful_payment` / VK callback. Клиентское «я оплатил»
+игнорируется. Что значит «проверенный», зависит от рельса: VK и Telegram подписывают свои колбэки,
+а **ЮKassa — нет** (D48), см. подтверждающее чтение ниже.
 
 **Единственный писатель.** Один платёжный домен — единственный, кто пишет в журнал операций.
-Публичные вебхуки (Robokassa/VK) терминируются на краю (Caddy/gateway) и проксируются в
+Публичные вебхуки (ЮKassa/VK) терминируются на краю (Caddy/gateway) и проксируются в
 платёжный домен; TG `successful_payment` приходит боту, тот форвардит в платёжный домен.
 Одно место начисляет и защищает от повторов.
 
 **Флоу заказа.** Сервер заранее создаёт `order(pending)` с account / платформой / пакетом /
-ожидаемой суммой / origin. `order_id` прокидывается провайдеру (Robokassa `InvId` / TG
-`invoice_payload` / VK `item` — точную форму VK уточнить при интеграции). Колбэк матчится по
-`order_id` (никогда по сумме, поэтому коллизии одинаковых сумм невозможны), сверяет сумму,
-начисляет, помечает `paid`. **Защита от повторов:** дедуп по `(провайдер,
-provider_payment_id)`.
+ожидаемой суммой / origin. `order_id` прокидывается провайдеру (ЮKassa `metadata.order_id` / TG
+`invoice_payload` / VK `item`). Колбэк матчится по `order_id` (никогда по сумме, поэтому коллизии
+одинаковых сумм невозможны), сверяет сумму, начисляет, помечает `paid`. **Защита от повторов:**
+дедуп по `(провайдер, provider_payment_id)`.
+
+**Direct-рельс (ЮKassa).** Открытие покупки — исходящий вызов API: сервер создаёт платёж
+(`POST /v3/payments`, `capture: true`, подтверждение через redirect, идентификатор заказа и как
+`Idempotence-Key`, и как `metadata.order_id`, плюс фискальный чек из §12) и отправляет покупателя на
+полученный `confirmation_url`. Идентификатор платежа сразу записывается в заказ — именно он позволяет
+потом перепроверить заказ и оформить возврат. Страница возврата браузера (`/pay/yookassa/return`)
+косметическая: начисление никогда не едет на редиректе.
+
+**Уведомление — подсказка, а не доказательство (D48).** ЮKassa не подписывает уведомления, поэтому
+действовать по содержимому тела нельзя. Оно лишь называет платёж, который сервер затем перечитывает
+запросом `GET /v3/payments/{id}`; доверяем только этому ответу. На нём же держатся две проверки:
+метаданные платежа должны называть тот самый заказ, а его флаг `test` — совпадать с флагом магазина,
+поэтому платёж тестового магазина никогда не начислит настоящие Фишки (и наоборот). В качестве
+эшелонированной защиты — и чтобы подделыватель не превращал каждое фальшивое уведомление в наш
+исходящий запрос — адрес отправителя сперва сверяется с опубликованными диапазонами ЮKassa. Ответ
+сообщает провайдеру, повторять ли доставку: 200 на всё, что решено окончательно, включая дубль и
+неустранимый отказ, и 5xx только на временный сбой (ЮKassa повторяет доставку 24 часа).
+
+**Сверка на истечении заказа (D49).** Постоянного опроса нет. Но безвозвратно потерянное уведомление
+оставило бы деньги списанными, а Фишки — не выданными, и молча. Поэтому уже существующий жнец
+просроченных заказов спрашивает у провайдера судьбу каждого заказа, который дожил до своего срока с
+идентификатором платежа, и начисляет те, что на самом деле оплачены. Один запрос на заказ за всю его
+жизнь.
+
+**Об отклонённой оплате сообщаем.** `payment.canceled` от ЮKassa пишет событие `failed`, поэтому
+покупатель узнаёт, что попытка не прошла, вместо разглядывания неменяющегося баланса. Просто
+брошенный заказ не пишет ничего — он молча истекает.
 
 **Pending невидим** пользователю; авто-истекает по таймауту (~30 мин, гигиена базы).
 Валидный колбэк исполняется **всегда**, даже на истёкшем заказе (`expired` ≠ отмена —
@@ -261,9 +298,13 @@ at-least-once + идемпотентный приём (дедуп по `telegram
 бота).
 
 **Возвраты.** ToS — **невозвратно**, пользователю возврат не предлагаем. Возвраты **инициирует
-админ** (консоль E7): ни один рельс не шлёт непрошеный возврат — Robokassa через refund-API / ЛК
-(авто-опрос статуса — отложенный воркер, при низком объёме чарджбеков не оправдан), VK — через
-поддержку, TG Stars — вызовом `refundStarPayment`. Все сходятся на одном движке — метод `Refund`
+админ** (консоль E7): ни один рельс не шлёт непрошеный возврат. На direct-рельсе консоль делает
+всю работу одним нажатием (D50): сперва вызывает refund-API ЮKassa (`POST /v3/refunds`,
+`Idempotence-Key` — идентификатор заказа, с чеком возврата из §12) и записывает реверс только после
+того, как деньги действительно ушли, — неудачный вызов не пишет **ничего**, поэтому журнал не может
+заявить о возврате, которого не было. Записывается собственный refund-id провайдера: по нему журнал
+сверяется с данными ЮKassa. Возвраты VK по-прежнему через поддержку, TG Stars — вызовом
+`refundStarPayment`, оба фиксируются руками после факта. Все сходятся на одном движке — метод `Refund`
 (`internal/payments`): матчит оплаченный заказ, пишет **refund**-строку журнала (идемпотентно по
 `(provider, provider_refund_id)` — refund-id отличается от payment-id fund'а, поэтому строки
 сосуществуют под тем же partial-unique индексом) и **по возможности отзывает начисленные Фишки с
@@ -349,7 +390,15 @@ in-process кэш сегментов и бенефитов по ключу-ак
 
 Чеки формируются автоматически **на стороне провайдера** и отличаются по каналу:
 
-- **Robokassa** (direct) — чек НПД самозанятого при оплате.
+- **ЮKassa** (direct) — фискальный чек по 54-ФЗ через **«Чеки от ЮKassa»**: касса, фискальный
+  накопитель, договор с ОФД и отправка в налоговую — на стороне ЮKassa. В отличие от кабинетных чеков
+  прежнего рельса, чек регистрируется **только если запрос его несёт** (D51), поэтому каждый платёж и
+  каждый возврат отправляют `receipt`: одна позиция (название пакета, количество 1, сумма) с кодом
+  ставки НДС (тег 54-ФЗ 1199, переменная деплоя — `1` = «Без НДС» для УСН/ПСН), признаком предмета
+  расчёта `service` (тег 1212) и признаком способа расчёта `full_payment` (тег 1214). Доставка только
+  на email — на подтверждённый якорь D36. `tax_system_code` не передаём: для этого решения ЮKassa его
+  игнорирует. Некорректный чек — ошибка API при создании платежа, то есть покупка ломается громко, а
+  не тихо остаётся без фискального документа.
 - **VK** — VK сам процессит Голоса через налоговую; делать нечего.
 - **TG Stars** — налоговой стороны нет (для РФ-самозанятого Stars легально невыводимы = не
   доход НПД; принимаем, чек не формируем).
@@ -359,7 +408,7 @@ in-process кэш сегментов и бенефитов по ключу-ак
 
 ## 13. Дистрибуция (native Android)
 
-- **RuStore** — Robokassa/внешний гейт разрешён (0%); native = чистый контекст `direct`.
+- **RuStore** — внешний платёжный гейт разрешён (0%); native = чистый контекст `direct`.
 - **Google Play** — direct-покупки **скрыты**; «Кошелёк» показывает заглушку («установите
   версию из RuStore для покупок»). Ролик за награду и трата уже накопленных Фишек работают.
   Перед GP-релизом свериться с актуальными правилами Google по внутренней валюте.
@@ -403,4 +452,4 @@ legacy-значения обнуляются.
   взнос).
 - **гейт** — одностороннее правило комплаенса сторов (§4).
 - **журнал операций (ledger)** — неизменяемая запись всех операций с деньгами/ценностями.
-- **платёжный канал / рельса** — платёжный провайдер (Robokassa / Голоса VK / Stars TG).
+- **платёжный канал / рельса** — платёжный провайдер (ЮKassa / Голоса VK / Stars TG).

gateway/internal/backendclient/api.go

@@ -514,6 +514,16 @@ func (c *Client) RobokassaResult(ctx context.Context, channel string, params map
 	return out.Response, err
 }
 
+// YooKassaNotify forwards a YooKassa webhook body verbatim to the backend intake (the single writer,
+// which re-reads the payment from the provider before acting on it — YooKassa does not sign
+// notifications). The backend answers 200 for anything durably decided and 5xx only for a transient
+// failure, so a nil error means the provider may stop redelivering.
+// clientIP is the true sender address, which only the gateway sees; the backend checks it against
+// YooKassa's published sender ranges.
+func (c *Client) YooKassaNotify(ctx context.Context, clientIP string, body json.RawMessage) error {
+	return c.do(ctx, http.MethodPost, "/api/v1/internal/payments/yookassa/notify", "", clientIP, body, nil)
+}
+
 // VKCallback forwards a gateway-verified VK payment callback's parameters to the backend intake and
 // returns the backend's raw VK response envelope (`{"response":…}` or `{"error":…}`) for the gateway
 // to relay to VK verbatim. The backend answers 200 in every case (VK's protocol), so a transport

gateway/internal/connectsrv/server.go

@@ -273,15 +273,20 @@ func (s *Server) HTTPHandler() http.Handler {
 	// through this session-gated route (not public); see dictBytesHandler.
 	mux.Handle("/dict/", s.dictBytesHandler())
 	mux.Handle("/dl/", s.exportDownloadHandler())
-	// Direct-rail (Robokassa) return + callback routes: the server Result callback (the single
-	// crediting signal, proxied to the backend intake) and the browser Success/Fail redirects. The
-	// per-shop callback rides a channel suffix (/pay/robokassa/result/<channel>); the bare path is
-	// the legacy web shop. Caddy's /pay/* matcher already forwards both, so no Caddyfile change.
+	// Direct-rail return + callback routes: the server notification (the single crediting signal,
+	// proxied to the backend intake) and the browser return page. Caddy's /pay/* matcher already
+	// forwards every path here, so a new route needs no Caddyfile change.
+	mux.Handle("/pay/yookassa/notify", s.yookassaNotifyHandler())
+	mux.Handle("/pay/yookassa/return", s.paymentReturnHandler("Оплата принята."))
+	mux.Handle("/pay/vk/callback", s.vkCallbackHandler())
+	// The retired Robokassa rail. Its routes stay registered — the backend simply has no shop to
+	// verify against — so reviving the rail is a credentials change, not a code change, and the
+	// edge probe keeps proving /pay/* reaches the gateway. The per-shop callback rides a channel
+	// suffix (/pay/robokassa/result/<channel>); the bare path is the legacy web shop.
 	mux.Handle("/pay/robokassa/result", s.robokassaResultHandler())
 	mux.Handle("/pay/robokassa/result/", s.robokassaResultHandler())
-	mux.Handle("/pay/vk/callback", s.vkCallbackHandler())
-	mux.Handle("/pay/robokassa/success", s.robokassaReturnHandler("Оплата принята."))
-	mux.Handle("/pay/robokassa/fail", s.robokassaReturnHandler("Оплата не завершена."))
+	mux.Handle("/pay/robokassa/success", s.paymentReturnHandler("Оплата принята."))
+	mux.Handle("/pay/robokassa/fail", s.paymentReturnHandler("Оплата не завершена."))
 	// The client posts its local-move-preview adoption telemetry here (session-gated).
 	mux.Handle("/metrics/local-eval", s.localEvalMetricsHandler())
 	// The index.html boot guard beacons here when it turns a client away on the unsupported-engine
@@ -691,6 +696,45 @@ func (s *Server) robokassaResultHandler() http.Handler {
 	})
 }
 
+// maxNotifyBytes caps the provider notification body the gateway will read and forward.
+const maxNotifyBytes = 1 << 20
+
+// yookassaNotifyHandler proxies a YooKassa webhook to the backend intake (the single writer). It
+// rate-limits per IP and forwards the raw JSON body together with the true sender address, which
+// only this hop sees; the backend checks that address against YooKassa's published sender ranges and
+// then re-reads the payment from the provider, because YooKassa does not sign notifications.
+//
+// The backend answers 200 for anything durably decided and 5xx for a transient failure, and that is
+// relayed as-is: YooKassa retries a notification for 24 hours until it gets a 200.
+func (s *Server) yookassaNotifyHandler() http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if s.backend == nil {
+			http.NotFound(w, r)
+			return
+		}
+		ip := peerIP(r.RemoteAddr, r.Header)
+		if !s.limiter.Allow("public:"+ip, s.publicPolicy) {
+			s.noteRateLimited(r.Context(), classPublic, ip, "yookassa-notify")
+			http.Error(w, "rate limited", http.StatusTooManyRequests)
+			return
+		}
+		body, err := io.ReadAll(io.LimitReader(r.Body, maxNotifyBytes))
+		if err != nil || !json.Valid(body) {
+			// Rejected here rather than proxied: a body that is not JSON cannot become valid on a
+			// redelivery, and forwarding it would only make the backend answer 5xx forever.
+			http.Error(w, "bad request", http.StatusBadRequest)
+			return
+		}
+		if err := s.backend.YooKassaNotify(r.Context(), ip, body); err != nil {
+			s.log.Warn("yookassa notify proxy failed", zap.Error(err))
+			http.Error(w, "not accepted", http.StatusBadGateway)
+			return
+		}
+		w.Header().Set("Content-Type", "text/plain; charset=utf-8")
+		_, _ = w.Write([]byte("ok"))
+	})
+}
+
 // vkCallbackHandler proxies a VK Mini Apps payment callback to the backend intake. It rate-limits
 // per IP, verifies the VK signature with the app's protected key (the backend holds no VK secret),
 // forwards the provider's parameters, and relays the backend's VK response envelope. A missing or
@@ -731,12 +775,12 @@ func (s *Server) vkCallbackHandler() http.Handler {
 	})
 }
 
-// robokassaReturnHandler serves a minimal self-closing page for Robokassa's Success/Fail browser
+// paymentReturnHandler serves a minimal self-closing page for a direct-rail provider's browser
 // return. The payment opens in a separate window, so on return this closes that window and drops the
 // customer back into the live app (never a cold app start); a link is the fallback if the window
-// cannot self-close. The credit rides the server Result callback, never this redirect — the wallet
+// cannot self-close. The credit rides the server notification, never this redirect — the wallet
 // updates in place from the payment push, with a return-focus refetch as the fallback.
-func (s *Server) robokassaReturnHandler(message string) http.Handler {
+func (s *Server) paymentReturnHandler(message string) http.Handler {
 	page := []byte(`<!doctype html>
 <html lang="ru"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1"><title>Оплата</title></head>
 <body style="font-family: system-ui, sans-serif; text-align: center; padding: 48px 20px; color: #1a1c20">

ui/e2e/wallet.spec.ts

@@ -67,7 +67,7 @@ test('wallet: buying a chip pack opens the provider payment page', async ({ page
   await page.locator('[data-kind="pack"]').getByTestId('buy-pack').click();
   await expect
     .poll(() => page.evaluate(() => (window as { __opened?: string }).__opened))
-    .toContain('robokassa');
+    .toContain('yookassa');
 });
 
 test('wallet: the tab sits between Friends and About', async ({ page }) => {

ui/src/lib/mock/client.ts

@@ -239,7 +239,7 @@ export class MockGateway implements GatewayClient {
     if (!p || p.kind !== 'pack') throw new GatewayError('not_a_pack');
     // No real provider in mock: return a stub launch URL so the e2e can assert the purchase reaches
     // the provider hand-off without leaving the app.
-    return { orderId: 'mock-order-' + productId, redirectUrl: 'https://mock.local/robokassa?order=' + productId };
+    return { orderId: 'mock-order-' + productId, redirectUrl: 'https://mock.local/yookassa?order=' + productId };
   }
 
   async walletReward(_nonce: string): Promise<Wallet> {