simplex-chat/docs/protocol/badges-rpc.md

Badge service RPC protocol

Schema: badges-rpc.schema.json, definitions request and response. Types: Simplex.Chat.Badges.Service. Model: plans/2026-07-30-supporter-badges-v3-ux.md §3 — cited below as "model".

Transport

Service RPC (plans/2026-07-22-service-rpc-chat.md, branch rpc): the request travels in APISendServiceRequest.request, the response in CRServiceResponse.responseData; one response per request; per-call timeout.

A request is an envelope: version — the client's protocol version; purchaseKey; request — the command, discriminated on type. Responses are discriminated on type. The service is deployed ahead of app releases, answers within the client's version, and rejects clients older than it supports with unsupported_version.

Identity

Each purchase runs under a fresh Ed25519 key pair; purchaseKey is its public part and identifies the badge. The service cannot link purchases of one user; the exceptions are the declared upgrades below. getBadgeCatalog may omit purchaseKey: unsigned, it returns the catalog alone; signed, its response adds the purchase's badgeStatement — a client holding a lapsed badge checks for credits in the same request that prices a new purchase, and buys under a fresh key only when the statement shows none. Every other command requires the key and is signed with it. The agent delivers the verified signer key alongside the request; the service rejects a purchaseKey that differs from it with bad_request, and a key it holds no record of with unknown_purchase_key.

A purchase record is created by getBadgeInvoice, or by purchaseBadge funded with apple, google, code, or receipt.

Idempotency

A timeout hides the outcome, so the client repeats the identical signed request at its next trigger, never on a poll timer.

• getBadgeInvoice — returns the open invoice again; a new invoice is created only when none is open.
• purchaseBadge — a payment already credited returns the same badgeCredential and writes nothing.
• 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.

Commands

purchaseBadge, upgradeBadgeSubscription, and issueBadge 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); its absence requests a lifetime credential; badgeExtra is reserved and must be empty.

• 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.
• purchaseBadge → badgeCredential — verifies the funding (apple JWS offline; google token via the Publisher API; invoice against webhook-confirmed settlement, payment_pending until it lands; code; 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.
  • 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.
• issueBadge → badgeCredential — issues the next period from the balance, the only source of issuance. 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).

Upgrades

Always a new purchase under a new key, except store subscriptions, where the store owns the change.

• Non-store: getBadgeInvoice.upgrade — fromPurchaseKey, the old purchase's receipt, receiptSignature binding the old key to the new, and the asserted old balance. The invoice returns the conversion credit; settlement records debit(upgrade) on the old purchase and the credit on the new.
• Store one-time: an upgrade SKU at a fixed discounted price; purchaseBadge.upgrade — fromPurchaseKey, receipt, receiptSignature — proves eligibility (an unexpired cheaper badge), because the store cannot gate who buys the SKU.
• Store subscription, app-led: the native subscription-group flow (Apple — immediate, with the store's prorated refund; Google — per replacement mode), then upgradeBadgeSubscription with the new evidence.
• Store subscription, sheet-led, and every downgrade: the client sends nothing — the service discovers the change from provider state and notifications, and each renewal credits months of the charged badge type.

Catalog

prices — priceId, badgeType, monthPrice, currency, status, createdAt; offers — offerId, priceId? (absent applies to any price), months, discount, status, createdAt. An offer states a discount, as free months or a percentage; a duration without one is priced at months × monthPrice. Repricing appends a price and deprecates the old, which is still accepted at invoice creation; deprecated prices and offers are sent so that a refresh cannot remove what the client pinned, and disabled ones are omitted. Rendering is app-driven — tiers and durations come from app resources, and one without a price is shown disabled.

Statement and balance

The ledger is written by the service alone (model §3); the client keeps a verbatim replica and computes the effective balance from its last entry and the time.

statement — entries, and previousEntryId when they attach after an entry the client holds; its absence marks entries that attach to nothing. Each entry states entryId, the signed changeMonths, the resulting balanceMonths, balanceStartTs, and balanceBadgeType, wasPausedSince on the entry ending a pause, createdAt, and entryType — credit: payment {invoiceId?}, charge {chargeId}, support, transferIn {fromPurchaseKey}, opening; debit: refund, upgrade {toPurchaseKey}, transferOut {toPurchaseKey}, support, badge, lapse. An unknown type is stored as received and decoded after an app upgrade.

balance — lastEntry, the client's last entry, asserting the position and the months it believes it holds.

An assertion that names an entry the service holds is a prefix: the service proceeds and returns what follows it. Otherwise the service heals its own ledger first — provider evidence for charges, time for lapses — proceeds, and returns either the complete history or one opening credit. An opening entry is an absolute restatement: the ledger is reset to the amount it states, without relation to the preceding entry, which also serves a new device and, later, the discarding of old history into a brought-forward balance.

Errors

retryAfter marks the transient codes: payment_pending, provider_unavailable, rate_limited. offer_disabled calls for a catalog refresh. code_invalid covers unknown and revoked codes; code_used — redeemed under another key. receipt_invalid covers unknown receipts. All other codes are terminal for the attempted command.