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Releases and Versions

This documentation is intended to stay version-aware without embedding a release number in every page title.

Current documented release

The current documented release is v0.4.1 and is recommended for new consumers.

Highlights since v0.4.0

  • Optimized PostgreSQL push-configuration create, get, list, and cleanup paths, reducing redundant task lookups, commands, and connection acquisitions while preserving authoritative task validation and concurrent-deletion safety.
  • Added optimistic revision-aware task persistence to the built-in stores so the example/TCK SendMessage path can persist complete task mutations with fewer PostgreSQL round trips while preserving concurrent history updates.
  • Added HTTP/1.1 persistent connections and connection-scoped request buffering, eliminating per-request connection churn for ordinary unary HTTP+JSON and JSON-RPC operations.
  • Optimized REST query parsing and reorganized transport implementation sources under dedicated client/server transport directories without changing public include paths.
  • Optimized HTTP+JSON and JSON-RPC ListTasks parsing and serialization through typed protobuf JSON paths, with focused parser/scanner benchmarks and CI thresholds.
  • Hardened typed ListTasks compatibility validation for null values, duplicate fields, protobuf-name aliases, nested duplicate message members, escaped JSON-RPC result keys, HTTP-status classification, and protobuf integer ranges.
  • Added component-level transport benchmarks for JSON-RPC envelopes, ProtoJSON, REST query parsing, response construction, and ListTasks client parsing.
  • Isolated performance fixtures from measured operations and restructured reports around concrete workload coordinates rather than mixed scenario averages.
  • Expanded PostgreSQL command-level diagnostics and documented storage, performance, and transport behavior.
  • Added repository-wide Conventional Commit validation in CI.

Compatibility notes

There are no intentional public API removals in v0.4.1.

The transport source-tree reorganization is internal; installed public include paths and exported CMake targets remain unchanged.

HTTP+JSON and JSON-RPC unary traffic can now reuse HTTP/1.1 connections. Explicit Connection: close remains supported, and the existing streaming/SSE behavior is preserved.

Valid ListTasks responses remain compatible across HTTP+JSON and JSON-RPC. Malformed or ambiguous JSON that protobuf 3.21 could otherwise accept with last-value-wins or null-as-unset behavior is now rejected consistently.

PostgreSQL users should allow SDK-managed schemas to migrate and validate the task-aware push-configuration helpers. Externally managed schemas should follow the storage documentation for the required schema objects and privileges.

Previous release: v0.4.0

v0.4.0 focused on configurable PostgreSQL pool sizing, bounded protocol-facing ListTasks pagination, optimized in-memory task listing, interruptible gRPC stream cancellation, expanded performance validation, and centralized HTTP server response construction.

Its important compatibility changes remain in effect:

  • omitted protocol-facing ListTasks.page_size defaults to 50;
  • explicit page sizes must be between 1 and 100;
  • the PostgreSQL connection pool defaults to 4 unless configured otherwise.

Earlier release: v0.3.0

v0.3.0 introduced production-ready SSE streaming for HTTP+JSON and JSON-RPC, end-to-end streaming and subscriptions across all supported transports, report-only performance testing, repository-local vcpkg overlay packaging, and expanded build and platform documentation.

Its TCK validation snapshot was:

  • 249 tests passed
  • 16 tests skipped
  • 0 executed test failures
  • 100.0% compatibility for tested, non-skipped requirements

Versioning guidance

  • Pin CMake FetchContent integrations to a release tag such as v0.4.1 or to a reviewed commit.
  • Prefer find_package(a2a_cpp CONFIG REQUIRED) for installed SDK packages.
  • Keep generated protobuf headers and linked SDK libraries from the same installed package or build tree.
  • Review release notes before upgrading between versions.

Documentation policy

Page titles and navigation should remain mostly version agnostic. Release-specific notes belong on this page or in clearly marked compatibility sections.