T402 v2.8.0—Stellar support + 42 packages across 47 networks→
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Changelog

This page documents the version history and release notes for T402 SDKs.

Version Strategy

T402 follows Semantic Versioning:

  • Major (X.0.0): Breaking changes
  • Minor (0.X.0): New features, backward compatible
  • Patch (0.0.X): Bug fixes, backward compatible

TypeScript SDK

v2.9.x (Current)

v2.9.0 - April 2026

  • T402PaymentError — Structured error class with cause, phase, and retryable fields
  • WDK Test Harness — Mock factories for unit testing
  • Multi-Chain Address Validation — EVM, TON, TRON, Solana, Bitcoin, Cosmos
  • Solana Versioned Transactions — Priority fees and Token-2022
  • TRON Energy Estimation — Dynamic fee limits
  • TON Jetton Transfer Verification — Enhanced verification
  • Multi-Provider RPC Failover — Health checks across providers
  • Payment Idempotency Manager — Payment deduplication
  • Webhook Manager — HMAC-SHA256 signed webhook delivery
  • Encrypted Backup/Recovery — Encrypted seed phrase backup
  • Compliance Manager — Provider pattern for compliance checks

v2.8.x

v2.8.0 - March 2026

  • New @t402/stellar package — Stellar blockchain support with Soroban SEP-41 USDC transfers
  • New @t402/spark package — Spark (Bitcoin L2) with Lightning Network integration
  • New @t402/policy package — Payment policy engine for AI agent spending guardrails
  • New @t402/observability package — Payment event tracking and Prometheus metrics
  • New @t402/facilitator-embedded package — In-process facilitator (no external service)
  • New @t402/wdk-facilitator package — WDK wallet → Facilitator adapter
  • New @t402/wdk-swap-jupiter package — Jupiter DEX aggregator for Solana
  • New @t402/wdk-lending package — DeFi lending protocol abstractions (Aave V3)
  • New @t402/wdk-fiat package — Fiat on/off-ramp abstractions (MoonPay)
  • New @t402/payments-mcp — One-command MCP payment client for Claude/Codex/Gemini
  • New create-t402-module — Module scaffolding CLI
  • New create-t402-agent — Agent provisioning CLI
  • ERC-7710 smart account delegation (client + facilitator, all 4 SDKs)
  • ERC-7715 spend permissions for recurring/high-frequency payments
  • Offer-Receipt extension (EIP-712 signing + server/client middleware, all 4 SDKs)
  • SVM settlement cache for duplicate prevention (all 4 SDKs)
  • assetTransferMethod + supportsEip2612 flags on EVM asset config
  • Bazaar marketplace MCP tools (search/pay/monetize)
  • Sign/verify, indexer, historical price MCP tools
  • XAU₮0 (Tether Gold) token support
  • Sui, Hedera, Algorand chain mechanism types
  • Bridge non-EVM destinations (Solana/TON/TRON via LayerZero)
  • RPC provider failover with circuit breaker
  • EAS identity attestation extension
  • T402SwapPay.sol atomic token conversion contract
  • AgentSkills SKILL.md specification
  • Agentic commerce demo
  • 42 packages total (was 39), 13 chain families (was 10), 47 networks

v2.7.x

v2.7.1 - February 2026

  • New @t402/erc8004 package — ERC-8004 Trustless Agents on-chain identity protocol
    • Identity resolution: resolveAgent(), parseAgentRegistry(), verifyPayToMatchesAgent()
    • Reputation queries: getReputationSummary(), submitFeedback()
    • Validation registry: submitValidationRequest(), getValidationStatus(), getValidationSummary()
    • Client hooks: erc8004ClientExtension() for pre-payment agent identity verification
    • Server hooks: erc8004ResourceServerExtension() with reputation and validation enrichment
    • After-settle hook: erc8004AfterSettleExtension() for automatic feedback submission
  • 3 new MCP tools for AI agent identity resolution in @t402/mcp
    • erc8004/resolveAgent — look up agent’s on-chain identity, registration file, and services
    • erc8004/checkReputation — query reputation score from trusted reviewers
    • erc8004/verifyWallet — verify payTo matches agent’s registered wallet

v2.6.x

v2.6.1 - February 2026

  • StreamingClient — SDK client for facilitator streaming endpoints (7 methods)
  • IntentClient — SDK client for facilitator intent endpoints (8 methods)
  • Fixed discovery API paths from /discovery/ to /v1/discovery/
  • Added Idempotency-Key support for settle deduplication

v2.6.0 - February 2026

  • Expanded to 36 packages under @t402 on npm
  • Cross-SDK feature alignment with Go, Python, and Java SDKs
  • Improved multi-chain support and documentation

v2.5.x

v2.5.0 - February 2026

  • New @t402/wdk-protocol package — T402 payment protocol for WDK wallet apps
  • 5 new MCP tools for AI agents with WDK wallets (wdk/getWallet, wdk/getBalances, wdk/transfer, wdk/swap, t402/autoPay)
  • MCP server now exposes 11 tools when WDK seed phrase is configured (6 base + 5 WDK)

v2.4.x

v2.4.0 - February 2026

  • Cosmos (Noble) support via @t402/cosmos
  • Hardware wallet support (Ledger, Trezor)
  • MCP server parity across all SDKs
  • Cross-SDK feature alignment

v2.3.x

v2.3.1 - January 2026

  • Added Stacks (Bitcoin L2) support via @t402/stacks
  • Added Polkadot Asset Hub support via @t402/polkadot
  • Improved TypeScript type exports for mechanism packages
  • Fixed NEAR mainnet contract ID configuration

v2.3.0 - January 2026

  • Added Tezos FA2 support via @t402/tezos
  • Added Aptos Fungible Asset support via @t402/aptos
  • Improved error messages for signature verification failures
  • Updated viem to v2.x

v2.2.x

v2.2.0 - December 2025

  • Added NEAR NEP-141 support via @t402/near
  • Added @t402/vue for Vue.js integration
  • Improved gasless payment reliability in @t402/wdk-gasless
  • Fixed Safari WebSocket connection issues in paywall

v2.1.x

v2.1.0 - November 2025

  • Added @t402/wdk-multisig for Safe multi-sig integration
  • Added @t402/wdk-bridge for LayerZero bridging
  • Improved Hono middleware edge runtime support
  • Fixed Next.js App Router streaming responses

v2.0.x

v2.0.0 - October 2025

  • Breaking: Migrated to CAIP-2 network identifiers
  • Breaking: Renamed payment schemes (exact, upto)
  • Added Protocol V2 with ResourceInfo and extensions
  • Added @t402/extensions for protocol extensions
  • Added multi-chain app support with smart routing
  • Improved tree-shaking with granular package exports

v1.x (Legacy)

v1.9.0 - September 2025

  • Last v1 release before v2 migration
  • Added TON Jetton support
  • Added TRON TRC-20 support
  • Fixed EIP-3009 signature encoding
⚠️

V1 is deprecated. Migrate to V2 for new features and security updates.

Facilitator Service

February 2026

  • Added TON mainnet and testnet settlement
  • Added Stacks mainnet and testnet settlement (exact-direct)
  • Added Cosmos/Noble mainnet and testnet settlement (exact-direct)
  • Added Solana testnet, Aptos devnet, Kusama Asset Hub
  • 50 networks, 81 kinds across 10 chain families

January 2026

  • Added Stacks settlement support
  • Added Polkadot Asset Hub settlement
  • Improved Redis cluster failover handling
  • Added Prometheus histogram metrics for latency tracking

December 2025

  • Added Tezos settlement support
  • Added Aptos settlement support
  • Added NEAR settlement support
  • Improved rate limiting with sliding window algorithm

November 2025

  • Added Protocol V2 endpoints
  • Added /supported endpoint for network discovery
  • Improved health check granularity
  • Added Grafana dashboard templates

October 2025

  • Added TON settlement support
  • Added TRON settlement support
  • Improved transaction retry logic
  • Added OpenTelemetry tracing

Migration Guides

V1 to V2 Migration

The main changes in Protocol V2:

  1. Network Identifiers: Changed from short names to CAIP-2 format

    // V1
network: 'ethereum'
 
// V2
network: 'eip155:1'

  2. Payment Schemes: Renamed for clarity

    // V1
scheme: 'eip3009'
 
// V2
scheme: 'exact'

  3. Package Imports: Granular exports for tree-shaking

    // V1
import { ExactEvmScheme } from '@t402/evm'
 
// V2
import { ExactEvmScheme } from '@t402/evm/exact/client'

See the Migration Guide for detailed instructions.

Deprecation Policy

  • Major versions: Supported for 12 months after next major release
  • Minor versions: Supported until next minor release
  • Security patches: Backported to current and previous major versions

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FAQ & Glossary