feat(offer): live catalog price list in the public offer, served by the render sidecar

Robokassa moderation requires the public offer to list every digital good with
its price. Move /offer/ off the static landing container to the render sidecar:
it splices the live catalog price list (§4.4) into the owner-edited
ui/legal/offer_ru.md and renders it with the shared ui/src/lib/offer.ts — one
renderer, no drift, always matching the current catalog with no redeploy.

- backend: /api/v1/internal/offer/pricing (internal, off the edge allow-list)
  projects the active catalog into two markdown tables — chip packs priced per
  rail (roubles / VK votes / Telegram Stars) and chip-priced values — through
  payments.Money so no float reaches the page. Cached in memory: warmed at boot,
  marked stale on every catalog mutation, so a served render issues no query.
- renderer: GET /offer/ fetches the tables and substitutes them at the
  <#pricing_template#> marker, then renders; offer_ru.md is baked into the image
  and marked is bundled from ui. GET /offer -> 301. Only /offer/ is edge-exposed.
- caddy: route /offer/ to the sidecar; drop the now-dead landing /offer/
  handlers and the vite emit-offer plugin.
- offer: fill §4.3 (the chip-payment wording) and drop the in-page back link.
- landing footer: a feedback link (the offer's Telegram contact) beside the
  offer link.
- docs (ARCHITECTURE, FUNCTIONAL +_ru, renderer README), CI /offer/ probe,
  unit + integration + node tests.

backend/internal/inttest/payments_catalog_test.go

@@ -4,6 +4,7 @@ package inttest
 
 import (
 	"context"
+	"strings"
 	"testing"
 
 	"github.com/google/uuid"
@@ -111,3 +112,44 @@ func TestPaymentsCatalogExcludesDeactivated(t *testing.T) {
 		t.Error("deactivated product must not appear in the storefront")
 	}
 }
+
+// TestOfferPricingReflectsCatalogEdits verifies the public-offer price list (§4.4) is projected from
+// the live catalog and its cache is invalidated on a catalog mutation: a newly created pack appears
+// with its per-rail prices, and archiving it through the service drops it from the next read.
+func TestOfferPricingReflectsCatalogEdits(t *testing.T) {
+	svc := newPaymentsService()
+	ctx := context.Background()
+	title := "OfferTest " + uuid.NewString()
+	id, err := svc.CreateProduct(ctx, payments.ProductInput{
+		Title: title,
+		Atoms: []payments.AtomLine{{Atom: "chips", Quantity: 50}},
+		Prices: []payments.PriceLine{
+			{Method: "direct", Currency: payments.CurrencyRUB, Amount: 20000},
+			{Method: "vk", Currency: payments.CurrencyVote, Amount: 30},
+			{Method: "telegram", Currency: payments.CurrencyStar, Amount: 100},
+		},
+	}, true)
+	if err != nil {
+		t.Fatalf("create pack: %v", err)
+	}
+
+	md, err := svc.OfferPricing(ctx)
+	if err != nil {
+		t.Fatalf("offer pricing: %v", err)
+	}
+	if row := "| " + title + " | 200.00 | 30 | 100 |"; !strings.Contains(md, row) {
+		t.Fatalf("offer pricing missing the new pack row %q\n%s", row, md)
+	}
+
+	// Archiving through the service marks the cache stale; the next read must reproject without it.
+	if err := svc.SetProductActive(ctx, id, false); err != nil {
+		t.Fatalf("archive: %v", err)
+	}
+	md, err = svc.OfferPricing(ctx)
+	if err != nil {
+		t.Fatalf("offer pricing after archive: %v", err)
+	}
+	if strings.Contains(md, title) {
+		t.Errorf("archived pack must drop from the offer pricing:\n%s", md)
+	}
+}

backend/internal/payments/catalog_admin.go

@@ -153,7 +153,11 @@ func (s *Service) CreateProduct(ctx context.Context, in ProductInput, active boo
 	if err := validateProduct(in, active); err != nil {
 		return uuid.Nil, err
 	}
-	return s.store.createProduct(ctx, in, active, s.clock())
+	id, err := s.store.createProduct(ctx, in, active, s.clock())
+	if err == nil {
+		s.markOfferStale()
+	}
+	return id, err
 }
 
 // UpdateProduct validates and replaces a product's title, atoms and prices. An active product must
@@ -166,7 +170,11 @@ func (s *Service) UpdateProduct(ctx context.Context, id uuid.UUID, in ProductInp
 	if err := validateProduct(in, active); err != nil {
 		return err
 	}
-	return s.store.updateProduct(ctx, id, in, s.clock())
+	if err := s.store.updateProduct(ctx, id, in, s.clock()); err != nil {
+		return err
+	}
+	s.markOfferStale()
+	return nil
 }
 
 // SetProductActive archives (active=false) or unarchives a product. Unarchiving revalidates the
@@ -181,11 +189,19 @@ func (s *Service) SetProductActive(ctx context.Context, id uuid.UUID, active boo
 			return err
 		}
 	}
-	return s.store.setProductActive(ctx, id, active, s.clock())
+	if err := s.store.setProductActive(ctx, id, active, s.clock()); err != nil {
+		return err
+	}
+	s.markOfferStale()
+	return nil
 }
 
 // DeleteProduct hard-deletes a product only when it has never been transacted (no order or ledger
 // row references it); otherwise it returns ErrProductTransacted and the caller archives instead.
 func (s *Service) DeleteProduct(ctx context.Context, id uuid.UUID) error {
-	return s.store.deleteProduct(ctx, id)
+	if err := s.store.deleteProduct(ctx, id); err != nil {
+		return err
+	}
+	s.markOfferStale()
+	return nil
 }

backend/internal/payments/offer.go

@@ -0,0 +1,125 @@
+package payments
+
+import (
+	"context"
+	"fmt"
+	"strings"
+)
+
+// pricingMarker is the token the owner-edited offer markdown (ui/legal/offer_ru.md, §4.4) carries
+// where the price list belongs. The render sidecar replaces it with the markdown [Service.OfferPricing]
+// returns before rendering the /offer/ page; the backend only produces the tables, never the marker.
+const pricingMarker = "<#pricing_template#>"
+
+// OfferPricing returns the public-offer price list (§4.4) as two markdown tables projected from the
+// active catalog: first the chip packs (funding chips with money, priced per rail — roubles / VK
+// votes / Telegram Stars), then the chip-priced values (what a player exchanges chips for). The
+// result is cached in memory and reprojected only after a catalog mutation (see [Service.markOfferStale]),
+// so a steady-state read issues no query — only the first read after an edit reprojects. The render
+// sidecar fetches it and splices it into the offer markdown at the pricing marker.
+func (s *Service) OfferPricing(ctx context.Context) (string, error) {
+	s.offerMu.Lock()
+	defer s.offerMu.Unlock()
+	if s.offerFresh {
+		return s.offerMD, nil
+	}
+	md, err := s.buildOfferPricing(ctx)
+	if err != nil {
+		return "", err
+	}
+	s.offerMD = md
+	s.offerFresh = true
+	return md, nil
+}
+
+// markOfferStale marks the cached offer price list for reprojection on the next [Service.OfferPricing]
+// read. Every catalog mutation calls it; it takes no I/O, so it never fails the mutation that triggers it.
+func (s *Service) markOfferStale() {
+	s.offerMu.Lock()
+	s.offerFresh = false
+	s.offerMu.Unlock()
+}
+
+// buildOfferPricing loads the active catalog and projects it into the offer tables.
+func (s *Service) buildOfferPricing(ctx context.Context) (string, error) {
+	entries, err := s.store.loadCatalog(ctx)
+	if err != nil {
+		return "", err
+	}
+	return projectOfferPricing(entries), nil
+}
+
+// projectOfferPricing renders the active catalog into the two offer tables. A chip pack (it carries
+// the chips atom) lists its per-rail money price; a value (no chips atom) lists its uniform chip
+// price. Rows keep the catalog's creation order. An empty section is omitted. Amounts are rendered
+// through [Money] so no floating point ever reaches the page (roubles show kopecks as "200.00",
+// whole-unit rails as integers); a missing rail price shows an em dash.
+func projectOfferPricing(entries []catalogEntry) string {
+	var packs, values []string
+	for _, e := range entries {
+		if isPackEntry(e) {
+			packs = append(packs, fmt.Sprintf("| %s | %s | %s | %s |",
+				offerCell(e.title),
+				offerPrice(e, string(SourceDirect), CurrencyRUB),
+				offerPrice(e, string(SourceVK), CurrencyVote),
+				offerPrice(e, string(SourceTelegram), CurrencyStar),
+			))
+		} else {
+			values = append(values, fmt.Sprintf("| %s | %s |",
+				offerCell(e.title), offerPrice(e, "", CurrencyChip)))
+		}
+	}
+
+	var b strings.Builder
+	if len(packs) > 0 {
+		b.WriteString("Приобретение внутриигровой валюты «Фишка»:\n\n")
+		b.WriteString("| Наименование | Рубли | Голоса в VK | Stars в Telegram |\n")
+		b.WriteString("| --- | --- | --- | --- |\n")
+		b.WriteString(strings.Join(packs, "\n"))
+		b.WriteString("\n")
+	}
+	if len(values) > 0 {
+		if len(packs) > 0 {
+			b.WriteString("\n")
+		}
+		b.WriteString("Использование внутриигровой валюты «Фишка»:\n\n")
+		b.WriteString("| Наименование | «Фишки» |\n")
+		b.WriteString("| --- | --- |\n")
+		b.WriteString(strings.Join(values, "\n"))
+		b.WriteString("\n")
+	}
+	return strings.TrimRight(b.String(), "\n")
+}
+
+// isPackEntry reports whether the catalog entry is a chip pack — it carries the chips atom (funds
+// chips with money) rather than being a chip-priced value.
+func isPackEntry(e catalogEntry) bool {
+	for _, a := range e.atoms {
+		if a.atomType == atomChips {
+			return true
+		}
+	}
+	return false
+}
+
+// offerPrice formats the entry's price for the given payment method and currency as a major-unit
+// string, or an em dash when the entry carries no such price.
+func offerPrice(e catalogEntry, method string, cur Currency) string {
+	for _, pr := range e.prices {
+		if pr.method == method && pr.currency == cur {
+			m, err := MoneyFromMinor(pr.amount, pr.currency)
+			if err != nil {
+				return "—"
+			}
+			return m.Major()
+		}
+	}
+	return "—"
+}
+
+// offerCell escapes an owner-entered title for a markdown table cell: a literal pipe would break the
+// column layout, and a newline would break the row.
+func offerCell(s string) string {
+	s = strings.ReplaceAll(s, "\n", " ")
+	return strings.ReplaceAll(s, "|", "\\|")
+}

backend/internal/payments/offer_test.go

@@ -0,0 +1,69 @@
+package payments
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/google/uuid"
+)
+
+// TestProjectOfferPricing checks the happy path: a chip pack priced on every rail and a chip-priced
+// value render into the two tables, pack table first, money formatted through Money.
+func TestProjectOfferPricing(t *testing.T) {
+	entries := []catalogEntry{
+		{
+			id:    uuid.New(),
+			title: "50 «Фишек»",
+			atoms: []atomQty{{atomType: atomChips, quantity: 50}},
+			prices: []priceRow{
+				{method: string(SourceDirect), currency: CurrencyRUB, amount: 20000},
+				{method: string(SourceVK), currency: CurrencyVote, amount: 30},
+				{method: string(SourceTelegram), currency: CurrencyStar, amount: 100},
+			},
+		},
+		{
+			id:     uuid.New(),
+			title:  "200 подсказок",
+			atoms:  []atomQty{{atomType: "hints", quantity: 200}},
+			prices: []priceRow{{method: "", currency: CurrencyChip, amount: 50}},
+		},
+	}
+	md := projectOfferPricing(entries)
+	for _, want := range []string{
+		"| Наименование | Рубли | Голоса в VK | Stars в Telegram |",
+		"| 50 «Фишек» | 200.00 | 30 | 100 |",
+		"| Наименование | «Фишки» |",
+		"| 200 подсказок | 50 |",
+	} {
+		if !strings.Contains(md, want) {
+			t.Errorf("projection missing %q\n---\n%s", want, md)
+		}
+	}
+	if strings.Index(md, "Приобретение") > strings.Index(md, "Использование") {
+		t.Errorf("the pack table must precede the values table:\n%s", md)
+	}
+}
+
+// TestProjectOfferPricingMissingRailAndEscaping checks a pack missing a rail shows an em dash and a
+// title carrying a pipe is escaped so the table layout survives.
+func TestProjectOfferPricingMissingRailAndEscaping(t *testing.T) {
+	entries := []catalogEntry{{
+		id:    uuid.New(),
+		title: "Bonus | pack",
+		atoms: []atomQty{{atomType: atomChips, quantity: 10}},
+		// A roubles price only — no VK, no Telegram.
+		prices: []priceRow{{method: string(SourceDirect), currency: CurrencyRUB, amount: 9900}},
+	}}
+	md := projectOfferPricing(entries)
+	if want := `| Bonus \| pack | 99.00 | — | — |`; !strings.Contains(md, want) {
+		t.Errorf("want row %q in:\n%s", want, md)
+	}
+}
+
+// TestProjectOfferPricingEmpty checks an empty catalog projects to the empty string (no stray table
+// headers), so the offer's pricing marker is replaced with nothing.
+func TestProjectOfferPricingEmpty(t *testing.T) {
+	if got := projectOfferPricing(nil); got != "" {
+		t.Errorf("empty catalog must project to empty string, got %q", got)
+	}
+}

backend/internal/payments/service.go

@@ -5,6 +5,7 @@ import (
 	"database/sql"
 	"encoding/json"
 	"fmt"
+	"sync"
 	"time"
 
 	"github.com/google/uuid"
@@ -19,6 +20,13 @@ import (
 type Service struct {
 	store *Store
 	clock func() time.Time
+
+	// offerMu guards the cached public-offer price list (§4.4). offerMD holds the projected
+	// markdown tables and offerFresh whether they are current; a catalog mutation clears offerFresh
+	// (markOfferStale) and the next OfferPricing read reprojects, so a served render issues no query.
+	offerMu    sync.Mutex
+	offerMD    string
+	offerFresh bool
 }
 
 // NewService constructs a Service over store with a wall-clock time source.

backend/internal/server/handlers.go

@@ -74,6 +74,9 @@ func (s *Server) registerRoutes() {
 		u.POST("/wallet/buy", s.handleWalletBuy)
 		// A rewarded-video credit (VK ads): client-attested + a config daily cap.
 		u.POST("/wallet/reward", s.handleWalletReward)
+		// The public-offer price list (§4.4) as markdown, for the render sidecar that serves the
+		// /offer/ page. Internal (off the edge allow-list); called by the renderer, not the gateway.
+		s.internal.GET("/offer/pricing", s.handleOfferPricing)
 	}
 	if s.payments != nil {
 		// The money order endpoint dispatches by rail (direct → Robokassa, vk → VK); an

backend/internal/server/handlers_wallet.go

@@ -112,6 +112,22 @@ func (s *Server) handleWalletCatalog(c *gin.Context) {
 	c.JSON(http.StatusOK, catalogDTOFrom(view))
 }
 
+// handleOfferPricing serves the public-offer price list (§4.4) as markdown — the two catalog tables
+// projected from the active products. The render sidecar fetches it and splices it into the offer
+// markdown before rendering the /offer/ page. Internal, non-public: the /api/v1/internal group is
+// off the edge allow-list, and the value is served from the payments cache (no per-request query in
+// the steady state). Called by the renderer, not the gateway.
+func (s *Server) handleOfferPricing(c *gin.Context) {
+	md, err := s.payments.OfferPricing(c.Request.Context())
+	if err != nil {
+		s.log.Error("offer pricing projection failed", zap.Error(err))
+		c.String(http.StatusInternalServerError, "offer pricing unavailable")
+		return
+	}
+	c.Header("Content-Type", "text/markdown; charset=utf-8")
+	c.String(http.StatusOK, md)
+}
+
 // handleWallet returns the caller's wallet — the segments and benefits visible in the current
 // trusted execution context, plus the rewarded-video payout available here (0 outside VK or when
 // unconfigured), which gates the client's "watch for chips" button.