core, ui: buy a badge with an App Store or Google Play purchase (#7590)

docs/protocol/badges-rpc.md

@@ -20,21 +20,28 @@ A timeout hides the outcome, so the client repeats the identical signed request
 
 - `getBadgeInvoice` — returns the open invoice again; a new invoice is created only when none is open.
 - `redeemBadgeCode` — a code already redeemed by the signing key returns the same `badgeCredential` and writes nothing; redeemed by another key, `code_used`. The client must therefore keep the key it first signed with, or a retry cannot be recognised.
-- `purchaseBadge` — a payment already credited returns the same `badgeCredential` and writes nothing.
+- `purchaseBadge` — a payment already credited returns the same `badgeCredential` and writes nothing; a store payment credited to another key, `receipt_used`.
 - `upgradeBadgeSubscription` — evidence already applied returns the same result and writes nothing.
 - `issueBadge` — repeated within an issued period, returns the cached credential and writes nothing.
-- `purchaseBadge` with a `receipt` — presented again by the same key it returns the same result; presented by another key, `receipt_used`.
+- `purchaseBadge` with the recovery `receipt` — presented again by the same key it returns the same result; presented by another key, `receipt_used`.
 
 ## Commands
 
-`purchaseBadge` and `upgradeBadgeSubscription` carry `badgeRequest`, the signer's input (`BadgeRequest`, `Simplex.Chat.Badges`): the service signs exactly this content or rejects the command. The proposed `badgeExpiry` is capped by the funded coverage (`sundayAfter`, model §3) and is required — a credential always expires, and a badge that does not is expressed as a long finite term; `badgeExtra` is reserved and must be empty. `issueBadge` carries no `badgeRequest`: the tier, the master key and the expiry are all the service's own, so there is nothing for the client to state.
+The client never states what is signed. The tier is that of whatever funded the purchase; the expiry is the `sundayAfter` of the period issued (`endOfMondayAfter` in code), shared by every credential of that week; `badgeExtra` is reserved and empty. A client-proposed expiry, even one capped by the funded coverage, would fall off that shared boundary and single its holder out of the week's anonymity set — so no command carries `badgeRequest`. `upgradeBadgeSubscription` still has the field in the schema; that is wrong and it must be dropped when the command is implemented.
 
 - `getBadgeCatalog` → `badgeCatalog` — the prices and offers; signed, also the purchase's `badgeStatement`. Store builds never send it: prices come from the store and SKUs from app config.
 - `getBadgeInvoice` → `badgeInvoice` — prices the purchase for `badgeInfo` and `paymentVia` (`card` — Stripe; `crypto` — btc, xmr). The response holds the generic `invoice` — `invoiceId`, `price`, `discount`, the upgrade `credit`, `amount` = price − discount − credit, `currency`, `expiresAt`, and `paymentTo` (`url` for card; `address` and `cryptoAmount` for crypto) — beside the badge part, `badgeType` and `months`. `priceId` pins the price the client displayed; `offerId` selects a discounted duration, and its absence buys one month at that price. Price and offer status is checked here only: `deprecated` is still accepted, `disabled` is rejected; a badge type with no active price yields `product_unavailable`.
 - `redeemBadgeCode` → `badgeCredential` — redeems a code, records the credit, and issues the first credential, in one round trip. It carries `masterKey` and `code` and no `badgeRequest`: a code states no tier and no expiry, so the credential is what reports them. Errors: `code_invalid` for an unknown or malformed code, `code_used` when another key redeemed it, `code_expired` past a redemption deadline.
-- `purchaseBadge` → `badgeCredential` — verifies the funding (`apple` JWS offline; `google` token via the Publisher API; `invoice` against webhook-confirmed settlement, `payment_pending` until it lands; `receipt`), records the credit, and issues the first credential, in one round trip. The response `receipt` is the recovery bearer secret (model § recovery); the service stores its hash; lifetime badges receive none.
+- `purchaseBadge` → `badgeCredential` — verifies the funding (`apple` JWS offline; `google` product id and token via the Publisher API; `invoice` against webhook-confirmed settlement, `payment_pending` until it lands; `receipt`), records the credit, and issues the first credential, in one round trip. It carries `masterKey` and no `badgeRequest`. The response `receipt` is the recovery bearer secret (model § recovery); the service stores its hash; lifetime badges receive none.
+  - A store transaction is claimed by its own id, read from the evidence before verification, and credited only when the verified transaction carries that same id. A receipt already credited to the signing key is answered from the record, without asking the store.
+  - Errors: `receipt_invalid`, `payment_pending`, `provider_unavailable` — see the classes below; `receipt_used` when another key was credited with it; `product_unavailable` for a product this service does not price; `provider_not_configured` when this deployment has no verifier for the store, terminal for the request since retrying cannot deploy one. `receipt_invalid` and `receipt_used` are the only answers on which the client drops the keys it signed with and finishes the store transaction. Every other answer records nothing and leaves the purchase with its keys, to be presented again at the next trigger.
+  - **Which class an answer belongs to.** The two mistakes do not cost the same, so when it is not certain, answer unreachable. `receipt_invalid` tells the client the purchase is dead: it drops the keys it signed with and finishes the store transaction — consumed on Play, finished on StoreKit — and nothing can present it again, so a buyer answered this by mistake has paid for a badge they can never receive. Answering unreachable by mistake costs one more verification request each time the app presents the purchase again, and a Play purchase left unacknowledged for three days is refunded to the buyer.
+    - **Terminal**, `receipt_invalid` — the store answered about this purchase and cannot change its mind: an Apple signature or certificate chain that does not verify, another app's bundle id, a test purchase (Apple Sandbox, Play `purchaseType` test), a refunded or revoked purchase, Play `purchaseState` canceled.
+    - **Pending**, `payment_pending` — Play `purchaseState` pending.
+    - **Unreachable**, `provider_unavailable` — the store was not asked or did not answer: network, timeout, 5xx, quota, this service's own auth or permission failures, and every Play error response, a 404 from `purchases.products.get` or `purchases.subscriptionsv2.get` and a 400 or 410 calling the token invalid included. A 404 decides nothing: Play answers it both for a token it has just issued and not yet recorded, and for one that was never a purchase. Only a purchase record is a verdict. A token whose characters this service will not send is never sent, so Play never answers about it — and Play documents no token grammar, so that check is our guess, not its verdict. A product id outside the characters Play does document is terminal, since no product of this app can have one.
+    - Apple is verified offline, so it has no "not yet" and a negative answer about the signed evidence is terminal. Two things are not the store's answer and leave the client holding the purchase: the verifier's own failure, such as a root certificate it could not load, which is `internal`; and a product this service does not price, which is `product_unavailable` — the verifier vouched for the transaction either way.
   - Funding by `receipt` is a transfer (post-MVP): the unissued months of the purchase that receipt belongs to move to the signing key, recorded as `debit(transferOut)` on the source and `credit(transferIn)` on the new purchase, and the presented receipt is retired for a fresh one. The transferred period's issuance debits a month like any other. Lifetime badges hold no receipt, so support handles them.
-- `upgradeBadgeSubscription` → `badgeCredential` — the app-led store subscription change, on the same key: verifies the store evidence of the replaced subscription and records the new plan; an immediate upgrade returns the new credential, a deferred change returns none.
+- `upgradeBadgeSubscription` → `badgeCredential` — the app-led store subscription change, on the same key: verifies the store evidence of the replaced subscription and records the new plan; an immediate upgrade returns the new credential, a deferred change returns none. Its `badgeRequest` is to be dropped (see above).
 - `issueBadge` → `badgeCredential` — issues the next period from the balance, the only source of issuance. It carries `balance` alone: the credential is signed with the purchase's stored master key, for the type the balance funds, expiring at the `sundayAfter` of the period issued. The ledger is advanced first; the credential is signed before the `debit(badge)` and issuance rows are written, in one transaction. An exhausted balance yields no `credential`; the `statement` shows why. Issuing on a paused badge resumes it (model 2.13).
 - `pauseBadge` (post-MVP) → `badgeCredential` — suspends issuance and lapse (model 2.13).
 
@@ -63,4 +70,4 @@ An assertion that names an entry the service holds is a prefix: the service proc
 
 ## Errors
 
-`retryAfter` marks the transient codes: `payment_pending`, `provider_unavailable`, `rate_limited`. `offer_disabled` calls for a catalog refresh. `code_invalid` covers unknown, malformed and revoked codes alike, so a guesser learns nothing from the difference; `code_used` — redeemed under another key; `code_expired` — past its redemption deadline. `receipt_invalid` covers unknown receipts. All other codes are terminal for the attempted command.
+`retryAfter` marks the transient codes: `payment_pending`, `provider_unavailable`, `rate_limited`. `offer_disabled` calls for a catalog refresh. `code_invalid` covers unknown, malformed and revoked codes alike, so a guesser learns nothing from the difference; `code_used` — redeemed under another key; `code_expired` — past its redemption deadline. `receipt_invalid` covers forged, malformed, another app's, refunded and test receipts alike, so a guesser learns nothing from the difference; `receipt_used` — credited to another key; `provider_not_configured` — no verifier for that store is deployed, so the receipt is neither credited nor refused. All other codes are terminal for the attempted command.

docs/protocol/badges-rpc.schema.json

@@ -95,7 +95,7 @@
           "properties": {"jws": {"type": "string"}}
         },
         "google": {
-          "properties": {"token": {"type": "string"}}
+          "properties": {"productId": {"type": "string"}, "token": {"type": "string"}}
         },
         "invoice": {
           "properties": {"invoiceId": {"type": "string"}}
@@ -309,7 +309,7 @@
         },
         "purchaseBadge": {
           "properties": {
-            "badgeRequest": {"ref": "badgeRequest"},
+            "masterKey": {"ref": "base64url"},
             "payment": {"ref": "payment"}
           },
           "optionalProperties": {
@@ -321,7 +321,10 @@
         },
         "upgradeBadgeSubscription": {
           "properties": {
-            "badgeRequest": {"ref": "badgeRequest"},
+            "badgeRequest": {
+              "ref": "badgeRequest",
+              "metadata": {"comment": "known wrong: to be dropped when implemented, see badges-rpc.md"}
+            },
             "payment": {
               "ref": "payment",
               "metadata": {"comment": "store payments only"}