Self-verified identity
Principal identity is anchored by Ed25519 public keys. Participants can verify signatures without depending on a single central registry.
What A2A Defines
不是函数调用格式，而是独立参与方之间的可验证协议层。
Signed protocol messages
JSON wire messages use snake_case fields, canonical signing behavior, message IDs, timestamps, risk levels, and typed message families.
Transactional flows
Offers, payment proof, delivery, cancellation, review, credentials, authorization, endorsements, disputes, and audit logs share one interface layer.
Evolution by RFC
Protocol changes are organized through documented RFC status folders, governance rules, SemVer compatibility, and release-facing artifacts.
Two-Layer Model
协议保持中立，平台策略承载运营差异。
Protocol Specification Layer
Field shape, wire behavior, cryptographic anchors
Defines identity, cards, message types, data assets, payment and dispute objects, error codes, and compatibility rules.
Platform Operator Layer
Escrow, KYC, registry, policy, dispute handling
Operators can implement business policy and service behavior while preserving the shared A2A wire contract.
Release-Facing Stack
一个仓库同时维护规范、真源、衍生产物与 SDK。
spec/
Current protocol specification in English, Simplified Chinese, and Traditional Chinese.
derived/
Derived TypeScript baseline and KEY_ROTATION protocol files.
truth-source/
Message vectors, error vectors, channel policy vectors, schemas, and interop matrix.
v1.0-package/
OpenAPI, JSON Schema, derivation tools, and baseline specification package.
rfcs/
Locked RFCs, full drafts, evaluation-only notes, deferred work, and governance materials.
SDK Implementations
Rust、Python、Go 覆盖 derived types、HTTP client/server、wire codec 与测试。
Rust
Derived types, HTTP interfaces, wire encoder/decoder, ID generator, and compatibility tests.
cd sdks/rust && cargo test
Python
Installable package with protocol types, SDK helpers, HTTP layers, wire codec, and pytest coverage.
pip install -e ".[dev,ed25519]"
Go
Generated protocol package, SDK HTTP helpers, wire codec, schemas, and interop test vectors.
cd sdks/go && go test ./...
Governance
协议演进有路径，兼容性有证据。
Locked specification
The release ships as a locked specification and SDK release set with status captured in STATUS.md.
Vector sync
SDK vector copies can be checked against truth-source materials with the repository maintenance script.
RFC status folders
Locked, draft, evaluation-only, and deferred materials keep protocol change discussion inspectable.
Build on the wire contract