Changelog

All notable changes to this project will be documented in this file.

Per-task history (acceptance criteria, scoring, decision notes) lives in roadmap/tasks.toml — query with rmap show <id> or read roadmap/data.json. This file is curated release notes only.

[Unreleased]

[0.11.0] — 2026-07-31

Changed — CI runs mix ci, and the security audit can no longer pass vacuously

.github/workflows/ci.yml invokes the mix ci (= mix precommit.full) alias instead of a hand-maintained step list, so CI and local dev share one gate definition. Three properties of that gate needed shoring up before the shared definition was trustworthy:

• deps.audit runs last. mix_audit signals a finding with System.stop(1), which is asynchronous — it returns, the alias proceeds, and the concurrent VM shutdown truncates the next step. Exit status was always non-zero, but the log showed an aborted dialyzer instead of the vulnerability report.
• deps.audit.gated proves the mirror was populated. MixAudit.Repo discards its clone/pull exit status, so a failed sync yields zero advisories and a passing report. The freshness prover catches that on the developer host but is a host script that skips on CI — precisely where a rate-limited clone would have produced a green "No vulnerabilities found." over nothing. The gate now also rejects a MIX_AUDIT_ADVISORY_PATH that diverges from MixAudit.Repo's hardcoded path (the prover honours the variable; the audit does not), and fails if cowboy enters mix.lock while .mix_audit_ignore still ignores GHSA-w4f7-4cxr-rv3c — --ignore-file takes advisory IDs only, never a package scope, and that advisory is genuine for cowboy < 2.16.0.
• reach.check is pinned to --path lib. Reach auto-discovers roots via */lib + */src wildcards, which picks up gitignored sibling checkouts (mpp-docs-fork/src) that don't exist on a runner. With smells: [strict: true] now gating, an unpinned scope would have graded different file sets locally and in CI.

Host-script skips also print via IO.puts rather than Mix.shell().info/1, which dialyzer.json --quiet had silenced for the remainder of the run, and the "is this runnable" guard is an executable-bit check rather than File.exists?/1 (true for directories and non-executable files, which raised an opaque ErlangError :enoent).

Changed — {:descripex, "~> 0.11"} → {:descripex, "~> 0.12.0"}

descripex 0.12.0 changed short_name in describe/1 output from an atom to a string — a consumer-visible contract change shipped at a minor bump, which the old two-segment ~> 0.11 (>= 0.11.0 and < 1.0.0) would have absorbed on any fresh resolution. The requirement is now three-segment (< 0.13.0); a 0.x package that breaks on minor earns the tighter form, and the cap gets raised deliberately after reading its release notes.

mpp does not read short_name — nothing in lib/ or test/ references it, and the full suite (1061 tests) is green against descripex 0.12.0 with no code change. The break is in the bound, not the behaviour. This release was already a minor for other reasons, so the narrowing costs no extra version step.

Changed — self-caps removed; styler 1.11.0 → 1.12.2

{:styler, "~> 1.11.0"} and {:ex_ast, "~> 0.12.0"} were three-segment self-caps blocking their own minor lines for no reason beyond how the bounds were written. Both dev/test only, so no effect on the published package. styler now resolves 1.12.2; ex_ast resolves 0.12.10 because reach 2.8.2 declares ex_ast ~> 0.12.0. That transitive requirement is a choice rather than a wall — override: true gets past it, as cartouche does — but the override is unmeasured here: ex_ast 0.13.0 changed pattern-matching semantics (map patterns became subset matching) and reach's smell checks are built on those patterns, so it could quietly report fewer findings. req resolves to 0.7.2.

styler 1.12 rewrote 19 lines of time arithmetic, DateTime.add(dt, n, :second) → DateTime.shift(dt, second: n) (normalised to minute:/hour: where the literal allowed). These are not unconditionally equivalent — shift/2 is calendar-aware and re-resolves the time zone, so on a DST zone it can differ from absolute-time addition. Every call site in MPP.Expires and MPP.Plug starts from DateTime.utc_now/0, and UTC has no DST, so the rewrite is safe here. Worth stating explicitly because the tests were rewritten the same way, which means a green suite alone would not have proven it.

Changed — dependency floors raised so the req 0.7 lift actually lands

• {:onchain, "~> 0.10"} → {:onchain, "~> 0.11"} and {:onchain_tempo, "~> 0.7"} → {:onchain_tempo, "~> 0.8"}. Those are the releases that carry cartouche ~> 0.6, which is what lifts cartouche's transitive req < 0.7 cap. The previous two-segment bounds already permitted the new versions but did not require them — and a lockfile entry that still satisfies its bound is never re-resolved, so a consumer sitting on onchain 0.10.0 would have gone on resolving cartouche 0.5.x, and therefore req 0.6.x, through any number of mix deps.get runs. Raising the floors invalidates the stale entries so the upgrade happens without anyone having to know to run mix deps.update.
• {:descripex, "~> 0.9"} → {:descripex, "~> 0.11"}, matching what cartouche 0.6 already forces.

Resolves to onchain 0.11.0, onchain_tempo 0.8.0, cartouche 0.6.0, descripex 0.11.0, req 0.7.1. Compiles --warnings-as-errors clean; 1061 offline tests pass (2 doctests, 13 properties).

Session intent schema. Added MPP.Intents.Session — pay-as-you-go / metered session request schema parallel to MPP.Intents.Charge, with new/1 validation, camelCase to_request/1 / from_request/1 matching mpp-rs SessionRequest (unitType, suggestedDeposit, methodDetails; transient decimals / external_id stripped from wire — mpp-rs session has no externalId). MPP.Method callbacks now accept MPP.Method.intent() (Charge.t() | Session.t()).

MCP server transport adapter (Task 32b). MPP.Mcp is now a mountable server-side transport, not just constants and helpers: MPP.Mcp.init/1 accepts the same endpoint options as MPP.Plug, and MPP.Mcp.call/3 runs a JSON-RPC request through payment verification before invoking the handler — reading the credential from params._meta["org.paymentauth/credential"], emitting -32042 payment-required / -32602 malformed-credential / -32043 verification-failed errors with challenges and RFC 9457 problem details (mppx mcpErrorCode parity), and attaching the receipt (+ challengeId) to result._meta on success. Challenge generation is shared with MPP.Plug, so both transports emit byte-identical challenges from the same config.

Credential replay dedup shared across transports (MPP.Replay). The plug-level credential single-use dedup (key mpp:credential:<challenge-id>:<payload-hash>, Tempo carve-out, atomic check_and_mark/2 only — GHSA-w8j7-7qc3-5f24) moved to an internal MPP.Replay module used by both MPP.Plug and the MCP transport, so a verified MCP credential cannot be replayed across JSON-RPC requests for store-backed methods.

Stripe Connect settlement options (Task 52). MPP.Methods.Stripe accepts an optional server-only "connect" map in method_config — destination charges (transfer_data destination/amount), direct charges (stripe_account → Stripe-Account header), application-fee splits (application_fee_amount), plus on_behalf_of and transfer_group — validated against the charge amount before PaymentIntent creation and never serialized into the public 402 challenge, matching mppx (validateConnectSettlement / createWithSecretKey).

Audit hardening on the above (dual-reviewer pass). Stripe PaymentIntent requests now pin Stripe-Version: 2026-02-25.preview (required for SPT private preview; mppx stripePreviewVersion parity) and reject a non-string Connect transfer_group cleanly instead of raising at request time. The MCP transport treats non-map JSON-RPC params (arrays, explicit null) as carrying no credential instead of crashing; its client helpers payment_required?/1 and extract_challenges/1 now also accept the full JSON-RPC response envelope (mppx paymentRequiredData parity); and a replayed MCP credential emits the same [:mpp, :verify, :start]/:fail telemetry as the HTTP path. MPP.Replay rejects a credential whose payload the JCS subset cannot canonicalize (e.g. floats) as malformed-credential instead of leaking a FunctionClauseError — also fixing the pre-existing crash on the HTTP path for store-backed methods.

[0.10.0] - 2026-07-08

Internal refactor — shared-helper de-duplication and MPP.Headers split (no runtime behavior change; the Accept-Payment API move below is the one breaking surface). Extracted copy-pasted internal helpers into three small modules: MPP.Hex (strip_0x/1, hex_string?/1), MPP.Methods.Shared (require_config/3, check_receipt_status/1, parse_charge_amount/1), and MPP.Codec (decode_base64_json/1), removing the duplication across the payment-method and wire-format modules. The 900-line MPP.Headers was split: the Accept-Payment parse/format/rank algorithm moved to its own MPP.AcceptPayment module, and the byte-level multi-scheme boundary state machine moved to an internal MPP.Headers.SchemeSplitter, leaving MPP.Headers focused on the challenge/credential/receipt wire format.

Breaking (moved API) — Accept-Payment functions relocated to MPP.AcceptPayment. The four public functions moved out of MPP.Headers and were renamed to drop the now-redundant suffix: MPP.Headers.parse_accept_payment/1 → MPP.AcceptPayment.parse/1, apply_accept_payment_header/3 → apply_header/3, format_accept_payment/1 → format/1, rank_by_accept_payment/2,3 → rank/2,3. Behavior is identical; the progressive-discovery key moves from MPP.describe(:headers) to MPP.describe(:accept_payment). Update any direct callers to the new module.

Parse-time input validation for challenges (reference-SDK parity). MPP.Headers.parse_challenge/1 and the echoed-challenge decode paths (MPP.Credential.decode/1, MPP.Mcp) now validate challenge field shapes at parse time instead of deferring to a downstream mismatch, via a shared MPP.Challenge.validate_fields/1: id must be non-empty, method must match the spec ABNF payment-method-id = 1*LOWERALPHA (lowercase ASCII letters only — following mpp-rs; mppx's looser [a-z0-9:_-] regex diverges from the spec), request must base64url-decode to a JSON object, and digest (when present) must start with sha-256=. The header/credential paths return distinct error atoms (:empty_id, :invalid_method, :invalid_request, :invalid_digest); the MCP transport keeps its coarse :invalid_challenge. MPP.Verifier now reports a malformed (non-ISO-8601) expires as a credential_mismatch distinct from an actual payment_expired, and MPP.JCS.canonicalize/1 raises ArgumentError on a non-string map key per its RFC 8785 contract. Raw wire bytes are never altered — validation only inspects shape, so HMAC binding is unaffected.

Tempo dedup stores now support per-store key prefixes for shared-cache tenancy. Pass key_prefix: "tenant:" in {MPP.Tempo.ConCacheStore, opts} to namespace backing keys while preserving the no-prefix default.

Audit hardening on the above (dual-reviewer pass). MPP.Credential.decode/1 now also rejects a non-string optional field (description/digest/expires/opaque in the echoed challenge, or the top-level source) with :invalid_optional_field — previously such a credential decoded successfully and crashed the verifier downstream (HMAC input join / ISO-8601 parse) on attacker-supplied wire bytes; mppx (z.optional(z.string())) and mpp-rs (serde Option<String>) both reject these shapes at deserialization. MPP.Mcp's JCS pre-check now rejects non-string map keys in a native request so they surface as :invalid_challenge instead of leaking the new MPP.JCS.canonicalize/1 raise. MPP.Plug.init/1 raises at boot when a configured method_name/0 falls outside the spec ABNF 1*LOWERALPHA — such a config would emit challenges that no compliant client (including this library's own parse paths) can parse.

[0.9.0] - 2026-07-08

Security (fee-payer intrinsic-gas hardening — closes an open item in the published gas-drain family). MPP.Methods.Tempo.FeePayerPolicy now rejects two non-canonical shapes in the client-signed 0x76 envelope before the server co-signs, matching mppx #602 (fix-fee-payer-intrinsic-gas): (1) any call carrying a nonzero native value, and (2) non-canonical calldata for the recognized TIP-20 / stablecoin-DEX calls (transfer, approve, transferWithMemo, swapExactAmountOut) — trailing padding or non-canonical high-order bytes that raise the transaction's intrinsic gas (16 gas per byte, paid by the sponsor) without changing the decoded payment intent. Both are siblings of the already-published gas-draining advisories (GHSA-vv77-66rf-pm86, GHSA-vj8p-hp9x-gh47, GHSA-qpxh-ff8m-c62v) that the existing price/access-list ceilings did not cover, and which pre-broadcast eth_simulateV1 cannot catch (padded calldata still executes successfully, it just costs more). Safe-by-default: honest clients emit canonical, zero-value calls, so existing fee_payer: true deployments are protected without config changes. Unrecognized selectors are left to the separate call-scope gate. mpp-rs does not implement this check (its fee-payer path uses a different inline-envelope architecture).

[0.8.0] - 2026-07-08

Security (presenter-identity binding — closes the GHSA-34g7-vx6g-82mq residual). New opt-in Tempo method_config key "require_presenter_binding": when true, type="hash" and type="transaction" credentials must carry a "presenterSignature" — an EIP-712 signature over the same Proof typed data the type="proof" path uses (MPP domain v3, {account, challengeId, realm}) — produced by the transfer sender's wallet or one of its authorized access keys. This closes the advisory's documented residual: dedup on the hash/transaction paths is keyed on the tx hash alone, so a third party who observed a settled transfer could race its hash against their own fresh challenge; with binding enabled the presenter must prove control of the sender address (hash path: the credential's source DID is required and must match the matched transfer's from; transaction path: the account is the sender recovered from the signed 0x76 transaction, and a source, when present, must agree). The requirement is advertised to clients as "presenterBinding": true in the 402 challenge's method details, and a supplied presenterSignature is verified even when the flag is off. Off by default for interoperability: neither mpp-rs nor mppx binds the presenter on the hash path (both default the expected sender to the receipt's from — mpp-rs verify_hash, mppx Charge.ts hash branch), so this is a deliberate hardening extension beyond the reference SDKs.

[0.7.0] - 2026-07-08

Security (Accept-Payment DoS cap — mpp-rs #299 parity). MPP.Headers.parse_accept_payment/1 and apply_accept_payment_header/3 now ignore an Accept-Payment header larger than 16 KiB (@max_token_len) before splitting, extending the credential/receipt/challenge-request token cap to the fourth client-supplied parse surface. Oversized headers are treated as malformed (spec MAY-ignore): parsing returns [] and offer ranking is a no-op.

Security (replay protection on by default — issue #7). Dedup stores are now on by default across all three layers (MPP.Plug credential store, MPP.Methods.Tempo, MPP.Methods.EVM). When no :store / "store" is configured, the app-started MPP.Tempo.ConCacheStore is used automatically, so a fresh install rejects replays out of the box instead of silently allowing them — matching the reference SDKs (mpp-rs store: Some(MemoryStore::new()) in server/tempo.rs; mppx Store.from(store ?? Store.memory()) in tempo/server/Charge.ts). The :mpp application is now started (via mod: {MPP.Application, []} in mix.exs) to supervise that default store.

Security (atomic dedup contract required — GHSA-w8j7-7qc3-5f24 residual). A configured store MUST now implement the atomic check_and_mark/2; check_and_mark/2 is a required MPP.Tempo.Store callback and a store lacking it is rejected at Plug.init / validate_config! with an ArgumentError. The previous non-atomic get/1+put/2 fallback — which left a TOCTOU replay window for custom get/put-only stores — has been removed. The built-in ConCacheStore (atomic via ConCache row isolation) and both reference SDKs (mpp-rs put_if_absent fails closed on AtomicUnsupported; mppx atomic update) already meet this contract.

Breaking changes (0.7.0):

• Replay protection defaults to ON. Deployments that relied on the previous stateless (no-dedup) default must set store: false (Plug opt) / "store" => false (method_config) to explicitly opt out. store: nil/absent now means "use the default store," not "no dedup."
• Custom stores implementing only get/1 + put/2 are rejected at init — add an atomic check_and_mark/2, or use store: false to disable dedup.
• The :mpp application now starts a supervised process (the default ConCacheStore). A static Tempo "memo" combined with store: false is rejected (a static memo still requires single-use enforcement).

[0.6.4] - 2026-07-07

Security (Tempo static-memo hardening — GHSA-34g7-vx6g-82mq). A static "memo" in the Tempo method_config now requires a dedup "store" to be configured — MPP.Plug raises ArgumentError at init otherwise. A static memo pins attribution independently of the per-challenge nonce, so the dedup store provides the single-use guarantee for that configuration, matching the reference Rust SDK's store-on-by-default backstop. Routes using the default per-challenge attribution (no static memo) are unaffected. Configure MPP.Tempo.ConCacheStore (or {MPP.Tempo.ConCacheStore, opts}) in your supervision tree, or omit the static memo.

[0.6.3] - 2026-07-06

Security (EVM payment-proof single-use — GHSA-vp5h-xh25-44wf). MPP.Methods.EVM gains an optional "store" config (an MPP.Tempo.Store module, or {MPP.Tempo.ConCacheStore, opts}) that makes each on-chain transaction hash single-use, closing a payment-proof replay gap: the method previously matched a settled transfer only by token/to/amount with no single-use binding, and the generic MPP.Plug store keys on the per-402 challenge.id, so one settled transaction could satisfy repeated charges on a static-price route. The tx hash is now checked before on-chain verification and atomically committed (check_and_mark/2, with a non-atomic put/2 fallback) after — keyed on the canonical (lowercased) hash rather than the challenge id, mirroring the Tempo type="hash" path. Store misconfiguration is rejected at init via validate_config!. Configure a store with a TTL ≥ your challenge expiry; residual per-challenge on-chain attribution is provided by the EIP-3009 authorization path (roadmap).

Dependency updates. Transitive: plug 1.20.1 → 1.20.2, cowlib 2.17.1 → 2.18.0, hpax 1.0.3 → 1.0.4, makeup 1.2.1 → 1.2.2; dev-only ex_ast 0.12.5 → 0.12.7.

[0.6.2] - 2026-06-30

Protocol utilities. Added MPP.Expires for ISO 8601 challenge-expiration helpers and MPP.DID.evm_did/2 for did:pkh:eip155 credential-source identifiers.

Security. MPP.Plug now accepts an optional shared replay store for generic credential deduplication across non-Tempo methods, using the existing MPP.Tempo.Store interface and atomic check_and_mark/2 when available.

Security (Tempo + Stripe hardening — Task 46). Tempo gains EIP-712 proof v3 credentials (MPP.Methods.Tempo.Proof, type="proof") with wallet-bound signatures, optional store dedup, and zero-amount enforcement. Fee-payer co-signing now rejects fee tokens outside a per-chain allowlist (FeePayerPolicy.default_allowed_fee_tokens/1, overridable via fee_payer_allowed_fee_tokens). MPP.DID.parse_evm_did/1 validates hash-credential did:pkh sources. MPP.Methods.Tempo.SessionReceipt adds optional externalId (PaymentWitness parity). Stripe rejects credential externalId values that disagree with the route request (mppx #537).

Security (Tempo proof access keys — Task 69). Zero-amount Tempo proof verification now accepts active delegated access-key signatures through the Tempo AccountKeychain path when the direct signer is not the root wallet, and rejects stale or revoked access keys.

Security (Tempo hosted fee payer — Task 68). Tempo charge verification can delegate fee-payer co-signing to a hosted eth_fillTransaction endpoint via fee_payer_url, matching mppx fillHostedFeePayerTransaction. Returned feeToken values are checked against the same sponsor allowlist as local co-signing before broadcast.

[0.6.1] - 2026-06-29

Security (Tempo hash-credential dedup). The type="hash" credential path now commits its dedup mark through the store's atomic check_and_mark/2 — the same primitive the type="transaction" path already uses — matching the reference SDKs (mpp-rs Store::put_if_absent, mppx atomic markHashUsed). The mark still happens only after successful on-chain verification, so a transient receipt-RPC failure does not burn a legitimate hash; stores that do not implement check_and_mark/2 keep the documented best-effort fallback.

Security hardening parity. Verifier/Plug now issue expiring challenges by default, fail closed on missing/invalid expiration, require echoed digest/opaque values to match endpoint configuration, and MCP clients recognize payment-required result metadata via org.paymentauth/payment-required. Tempo validates declared payer source against the matched transfer sender and chain, verifies challenge-bound attribution metadata on unconfigured memo transfers, and provider/RPC/store failure details are sanitized before becoming public 402 responses. Breaking: credentials for newly-issued challenges must echo valid expiration data, and Tempo no-static-memo routes now require challenge-bound attribution metadata.

Development tooling. The dev baseline now pins Elixir 1.20.2-otp-29, adds ex_slop and reach to mix precommit.full, refreshes the generated agent instructions, and includes MCP config for Cursor/Codex/Grok agents. Tempo's unsupported-eth_simulateV1 degraded-mode log is now a warning so missing node support is visible during operations.

[0.6.0] - 2026-06-24

CI / security scaffolding. The repo gains GitHub Actions CI — previously it had none. A base CI workflow gates every push/PR to development/main with the full check stack (format, --warnings-as-errors compile, Credo strict, Doctor, Sobelow, tests at a 95% coverage floor, Dialyzer), mirroring mix precommit.full; an Integration workflow runs the credential-gated :integration suite nightly (and on PR / manual dispatch), flunking loudly when secrets are absent rather than reporting a green 0-test run. A Code Scanning workflow uploads Sobelow findings to the Security tab as SARIF (CodeQL has no Elixir support), plus a Dependabot config (weekly Hex + Actions updates) and an expanded SECURITY.md scope. Elixir/OTP are pinned via .tool-versions so CI never drifts from local mix format output.

Security (Tempo fee-payer gas draining). When the server acts as fee payer it now validates the client-signed 0x76 envelope's gas economics before co-signing, closing two reported gas-draining vectors (GHSA-vv77-66rf-pm86, GHSA-qpxh-ff8m-c62v): unbounded max_fee_per_gas/max_priority_fee_per_gas and access-list padding. A new MPP.Methods.Tempo.FeePayerPolicy bounds gas_limit, max_fee_per_gas, max_priority_fee_per_gas, the gas × max_fee_per_gas total-fee budget, and rejects non-empty access lists. Cross-checking against the mppx and mpp-rs reference SDKs surfaced a further defense both enforce that we were missing — folded in here: the sponsored transaction must use the expiring nonce key and declare a valid_before that is in the future and within max_validity_window_seconds (default 15 min), so a client cannot hold a co-signed sponsorship broadcastable far into the future. All ceilings (gas economics + validity window) default to the reference-SDK values (per-chain; Moderato gets a higher priority-fee ceiling) and are overridable via method_config["fee_payer_policy"]. Safe-by-default — existing fee_payer: true deployments are protected without config changes. Complementing this static policy, the server now pre-simulates the full co-signed sponsored transaction via eth_simulateV1 before broadcasting — on both the synchronous and optimistic paths: a transaction that would revert on-chain is rejected before the sponsor commits any gas, a node without eth_simulateV1 (JSON-RPC -32601) degrades gracefully, and any other RPC error fails closed. This covers the residual class that static gas bounds cannot — a gas_limit set too low to complete execution. The onchain_tempo floor is raised to ~> 0.7 (lock 0.7.0) for the sender-recovery + Onchain.Tempo.RPC.simulate/3 primitives MPP.Methods.Tempo calls directly; the reference SDKs name the method tempo_simulateV1, but Tempo deploys the AA-aware EVM-standard eth_simulateV1 (both mainnet and Moderato return -32601 for the former).

Dependency updates. Runtime: req ~> 0.5.17 → ~> 0.6.1 (cascades transitive finch ~> 0.17 → ~> 0.21/0.22; MPP uses only the stable Req.request/2 + Req.Response/Req.Request surface, no code changes). Dev/test JS tooling moved as a set now that quickbeam relaxed its constraints: quickbeam 0.10.5 → 0.10.15, oxc ~> 0.13.0 → ~> 0.15.1, npm ~> 0.6.1 → ~> 0.7.4; ex_unit_json ~> 0.4.3 → ~> 0.5.0; dev-only bandit ~> 1.11.1 → ~> 1.12.0.

On-chain stack advanced to the onchain-0.10 line: descripex ~> 0.7.0 → ~> 0.9, onchain ~> 0.7.0 → ~> 0.10, onchain_tempo ~> 0.2.2 → ~> 0.7 (the onchain bump is what moves MPP.Methods.EVM onto the Onchain.RPC surface). This required moving the whole ZenHive on-chain family together — descripex 0.8/0.9 add spec-derived JSON Schema and are additive, but descripex 0.9.1 was cut alongside to fix a safe_convert crash (it only rescued ArgumentError, so real-world specs like Cartouche's %{required(non_neg_integer()) => <<_::256>>} aborted the manifest/describe build with an uncaught CaseClauseError). The lock resolves the family at descripex 0.11.0, cartouche 0.5.0, onchain 0.10.0, onchain_tempo 0.7.0 (cartouche 0.5 carries the descripex ~> 0.11 floor). Compile clean under --warnings-as-errors; offline tests green against the full updated chain, integration suite green.

[0.5.1] - 2026-06-09

Dependency updates. Bumped the onchain stack to the 0.7.0 line: onchain ~> 0.5.4 → ~> 0.7.0, onchain_tempo ~> 0.2.1 → ~> 0.2.2, descripex ~> 0.6.0 → ~> 0.7.0. onchain 0.7.0 cascades a major decimal 2.4.1 → 3.1.1 jump (transitive only — MPP has no direct Decimal use) and pulls cartouche 0.2.2. Dev-tool doctor advanced ~> 0.22 → ~> 0.23 (0.23 requires decimal ~> 3.1, unblocked by the jump). No library code changes — compile clean under --warnings-as-errors, 601 offline tests green.

[0.5.0] - 2026-05-15

Tempo session-receipt support and a client-side HTTP transport. Tempo integration tests now use Onchain.Tempo.Faucet for per-test fresh wallets instead of hardcoded keys, removing nonce coupling and unblocking a future move to async tests. MPP.Client.Transport behaviour with an HTTP implementation lands as the client-side counterpart to server-side MPP.Method, exposing a select_challenge/2 helper that Task 33c (Req plugin) and Task 33d (MCP) will reuse. Dependency floors tightened: onchain ~> 0.5, onchain_tempo ~> 0.2. A second cross-SDK gap pass added Tasks 36–42 (Stellar Charge, Accept-Payment, EVM credentialTypes/Permit2/EIP-3009, Tempo SessionReceipt, OpenAPI discovery) to the roadmap.

[0.4.0] - 2026-04-18

The first cross-SDK gap pass with substance. MPP.Verifier extracts the verification pipeline (HMAC, realm, expiry, request match, method.verify) out of MPP.Plug into a transport-neutral module, so MCP and future transports share the same correctness gate. MPP.JCS implements the RFC 8785 subset MPP needs for cross-SDK HMAC interop. The MCP transport (MPP.Mcp) lands with -32042/-32043 error codes and the org.paymentauth/credential + org.paymentauth/receipt _meta keys. Client-side gets MPP.Client.PaymentProvider behaviour and MultiProvider first-match dispatch. Protocol utilities fill in: MPP.Headers.parse_challenges/1 (multi-challenge WWW-Authenticate parsing), MPP.BodyDigest, MPP.Amount (parse_units / with_base_units / parse_dollar_amount). Eight new RFC 9457 session error types added under paymentauth.org/problems/session/. EVM integration tests against Sepolia validate real RPC round-trips for both ERC-20 and native-ETH paths.

Breaking: MPP.Amount.parse_dollar_amount/2 now requires callers to supply decimals explicitly (previously a single-arg form inferred it from currency). Neither mppx nor mpp-rs maintain a currency-to-decimals table; implicit inference was a correctness risk.

Scope decision: proxy/gateway functionality scoped out to a separate mpp_proxy package. The mpp library focuses on protocol correctness; the BEAM-native payment gateway is a separate product surface.

Dependency bumps: quickbeam 0.8.1 → 0.10.0, oxc 0.5.4 → 0.7.2, ex_dna 1.2.2 → 1.3.0, credo back to hex ~> 1.7 (upstream shipped the Elixir 1.20-rc multi-line sigil fix).

[0.3.0] - 2026-04-03

Generic EVM payment method and the onchain_tempo extraction. MPP.Methods.EVM verifies hash-only credentials on any EVM chain (Ethereum, Base, Polygon, Arbitrum, …) — ERC-20 transfers via Transfer event log parsing, native ETH via tx value/recipient matching. Tempo chain primitives moved out of MPP into the standalone onchain_tempo Hex package; MPP delegates chain ops and keeps only the payment-protocol surface (dedup store, eth_call simulation, RFC 9457 error wrapping). mix mpp.demo ships an interactive Bandit server on port 4402 with a toy demo-token method and a pre-computed valid credential in the startup banner — zero-friction first experience. Read-only live-protocol integration tests against mpp.dev/api/ping/paid validate parser compatibility with the reference server. MPP.Tempo.Store moduledoc gained deployment-topology guidance (ConCacheStore for single-node / sticky routing; shared backend otherwise, with fly-replay as a worked example).

[0.2.0] - 2026-03-28

The Tempo payment method (MPP.Methods.Tempo) — on-chain TIP-20 transfer verification with both type="hash" (client-broadcast) and type="transaction" (server-broadcast) credential paths. transferWithMemo(address,uint256,bytes32) matching enforced when methodDetails.memo is configured. Server-side fee sponsorship via 0x78 domain signing with whitelisted call-scope validation matching mppx's four allowed selector patterns. Optimistic broadcast mode (wait_for_confirmation: false) simulates the payment call via eth_call, broadcasts asynchronously, and returns an optimistic receipt without waiting for inclusion. MPP.Tempo.Store behaviour adds pluggable replay protection with get/put + optional atomic check_and_mark/2; built-in MPP.Tempo.ConCacheStore provides ETS-backed TTL dedup. MPP.Plug's :methods option enables multi-method 402 endpoints with per-method pricing. All public functions gain Descripex api() annotations with MPP.describe/0-2 progressive discovery and mix mpp.manifest for JSON API contract export. Bug fixes covered the TransferWithMemo memo indexed-topic discovery (via real Moderato receipts), v-value normalization for ox/tempo SDK interop, hash-path dedup ordering to avoid burning hashes on transient RPC failures, and crash protection in post-broadcast store paths.

[0.1.0] - 2026-03-25

First public release. Core protocol — HMAC-SHA256-bound Challenge, Credential, Receipt, Headers (WWW-Authenticate / Authorization / Payment-Receipt), and RFC 9457 problem types under paymentauth.org/problems/. MPP.Methods.Stripe verifies PaymentIntents via SPT with idempotency, analytics metadata, and Req.Test mockability. MPP.Plug mounts in any Phoenix or Plug router with per-route pricing and explicit credential configuration — no Application.get_env, no ENV fallback.