Update A2a Spec

Update A2A Protocol Specification

Follow these steps to update the TCK after an A2A protocol specification change.

Step 1: Capture the current state

Before updating, record what we have now so we can diff later.

1. Read specification/version.json to note the current commit hash.
2. Save copies of the key spec files for diffing:
   • specification/specification.md
   • specification/a2a.proto

Step 2: Download the updated specification

Ask the user if they want to update from the main branch or pass a tag or a commit cheksum

Run:

make spec

This executes scripts/update_spec.sh, which downloads the latest spec files from the upstream a2aproject/A2A GitHub repository and updates specification/version.json.

If updating from a fork or a different branch, pass arguments:

./scripts/update_spec.sh --org <org> --branch <branch>

Step 3: Regenerate gRPC stubs and JSON schema

Skip this step if specification/a2a.proto did not change (diff shows no proto changes).

gRPC stubs

Run:

make proto

This executes scripts/generate_grpc_stubs.sh, which uses buf to regenerate specification/generated/a2a_pb2.py and specification/generated/a2a_pb2_grpc.py from the updated a2a.proto.

If buf is not installed, first run ./scripts/install_buf.sh.

After regenerating, check the protobuf version in the generated stubs (head -5 specification/generated/a2a_pb2.py) and verify it is compatible with the protobuf runtime version installed in the project (see pyproject.toml). If the gencode version is newer than the runtime allows, pin the plugin versions in specification/buf.gen.yaml to a compatible release (e.g., buf.build/protocolbuffers/python:v30.2).

JSON schema

Ask the user for the path to their local googleapis checkout, then run:

PATH="$HOME/go/bin:$PATH" GOOGLEAPIS_DIR=<path-to-googleapis> make jsonschema

This regenerates specification/a2a.json from the updated a2a.proto. It requires:

• protoc-gen-jsonschema, installed via go install github.com/bufbuild/protoschema-plugins/cmd/protoc-gen-jsonschema@latest
• GOOGLEAPIS_DIR set to the user's local googleapis checkout

IMPORTANT: Never edit specification/a2a.json manually — always regenerate it from the proto.

Step 4: Analyze specification changes

Compare the old and new versions of the specification to identify changes:

1. Diff specification/specification.md to find:

   • New operations or endpoints
   • Changed request/response schemas
   • New or modified MUST/SHOULD/MAY requirements
   • Removed or deprecated features

2. Diff specification/a2a.proto to find:

   • New or changed message types
   • New or changed RPC methods
   • New or changed fields

3. Summarize the changes for the user before proceeding.

Step 5: Update transport bindings and requirements

Based on the spec diff, update the relevant files in tck/requirements/:

• base.py - Core enums (OperationType, HTTP methods, error codes) and base classes
• core_operations.py - Core operation requirements (CORE-OPS-*)
• binding_grpc.py - gRPC-specific requirements (GRPC-*)
• binding_jsonrpc.py - JSON-RPC-specific requirements (JSONRPC-*)
• binding_http_json.py - HTTP+JSON-specific requirements (HTTP_JSON-*)
• data_model.py - Data model requirements
• streaming.py - Streaming requirements
• push_notifications.py - Push notification requirements
• agent_card.py - Agent card requirements
• auth.py - Authentication requirements
• versioning.py - Versioning requirements
• interop.py - Interoperability requirements

For each spec change:

• If a new requirement is added, create a new requirement entry with the appropriate ID prefix and level (MUST/SHOULD/MAY).
• If a requirement is modified, update the existing entry.
• If a requirement is removed, remove the entry and note it.

Summarize the changes for the user before proceeding.

Step 6: Update transport clients and validators

If the spec changes affect transport-level behavior:

• Transport clients are in tck/transport/
• Response validators are in tck/validators/
  • tck/validators/error_info.py — shared ErrorInfo validation for JSON-RPC and HTTP+JSON (ProtoJSON @type format)
  • tck/validators/grpc/error_validator.py — gRPC ErrorInfo extraction (binary protobuf)
  • tck/validators/http_json/error_validator.py — AIP-193 error format parsing
  • tck/validators/jsonrpc/error_validator.py — JSON-RPC error code validation
  • tck/validators/error_binding.py — cross-transport expected-error validation

Step 7: Update or add conformance tests

Tests are in tests/compatibility/:

• core_operations/ - Cross-transport parametrized tests
• grpc/ - gRPC-specific tests
• jsonrpc/ - JSON-RPC-specific tests
• http_json/ - HTTP+JSON-specific tests
• agent_card/ - Agent card tests (discovery, caching, signing)

Each test class uses markers from tests/compatibility/markers.py (@grpc, @jsonrpc, @http_json, @core, @must, @should, @may).

Tests use helpers from tests/compatibility/_test_helpers.py:

• get_client() — get transport client with skip-on-missing handling
• record() — record result to compatibility collector
• fail_msg() — format assertion message with requirement context

Tests record results with:

compatibility_collector.record(requirement_id, transport, level, passed, errors)

When writing tests, prefer using transport clients (client.get_task(), client.cancel_task(), etc.) over raw HTTP calls. Only use raw httpx calls when the test needs custom headers (e.g., A2A-Version), invalid methods, malformed payloads, or wrong Content-Type.

Step 8: Validate

Run the linter and unit tests:

make lint
make unit-test

Fix any issues before proceeding. Common failures after a spec update:

• Proto package namespace changes (e.g., a2a.v1 to lf.a2a.v1) can break unit tests that assert on fully-qualified proto type names. Search for hardcoded package names in tests/unit/.
• Proto package namespace changes also affect $ref values in the regenerated JSON schema (e.g., a2a.v1.Task.jsonschema.json → lf.a2a.v1.Task.jsonschema.json). The $ref mapping in tck/validators/json_schema.py must support the new prefix, otherwise nested schema validation silently passes (refs resolve to permissive fallbacks).
• Protobuf runtime version mismatches (see Step 3).

Step 9: Audit requirements

Before committing, audit all requirement files to verify:

• Each requirement's section field matches the correct section in the updated specification.
• Each requirement's spec_url anchor resolves to the right heading.
• No requirements reference sections or content that was removed or renamed.
• Any new MUST/SHOULD/MAY requirements in the spec have corresponding entries.

To verify anchors programmatically, note that GitHub strips dots and special characters from heading text when generating anchors. For example, heading #### 3.1.1. Send Message produces anchor #311-send-message (not #3.1.1.-send-message). The SPEC_BASE constant in base.py is specification/specification.md#, and the _spec_url_to_href() function in html_formatter.py converts these to absolute GitHub URLs using the commit hash from version.json.

Highlight any new, modified, or removed requirements for the user.

Step 10: Summarize

Present the user with a summary of:

• The old and new spec commit hashes (from specification/version.json)
• What changed in the specification
• What was updated in the TCK (requirements, tests, transport code)
• Any areas that need manual review or additional test coverage