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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 v0.4.0 and is recommended for new consumers.

Highlights since v0.3.0

  • Configurable PostgreSQL connection pool capacity through PostgresStoreOptions::connection_pool_size, with the backward-compatible default of 4.
  • Shared configured PostgreSQL pools for task and push-notification stores created through CreateStoreBundle().
  • PostgreSQL operation-phase diagnostics, pool-size metadata, median aggregates, and query-plan evidence in performance reports.
  • Removal of executor-wide request serialization that limited independent concurrent operations.
  • Bounded protocol-facing ListTasks pagination across HTTP+JSON, JSON-RPC, and gRPC, with a default page size of 50 and a maximum of 100.
  • Optimized in-memory task listing, pagination, filtering, artifact exclusion, and history projection, backed by expanded benchmark thresholds.
  • Interruptible gRPC stream cancellation watching, eliminating the previous approximately 50 ms normal stream-completion floor.
  • Deterministic follow-up and decomposed push-notification performance scenarios with clearer workload attribution.
  • Expanded normal and PostgreSQL-tail performance matrices, reports, tests, and parallel CI execution.
  • Centralized HTTP server response construction and reusable server-side A2A-Version header validation.
  • Corrected benchmark-runner module paths and refreshed README, installation, storage, pagination, and performance documentation.

Compatibility notes

There are no intentional public API removals in v0.4.0.

Protocol-facing ListTasks requests are now bounded consistently across transports. An omitted page size returns at most 50 tasks, explicit values must be between 1 and 100, and callers must follow next_page_token to retrieve additional pages. Internal store calls may still use the documented unbounded sentinel where appropriate.

The PostgreSQL connection pool still defaults to 4, so existing applications retain their previous capacity unless they explicitly configure a different value. Applications should size the pool for expected concurrent database operations while respecting PostgreSQL connection limits.

Built-in HTTP+JSON and JSON-RPC SSE clients continue to require libcurl support. Custom HTTP requester and streaming requester implementations remain supported for consumers that need alternative transport stacks.

Previous 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 v0.4.0 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 minor 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.