# Update A2a Proto

> Update the A2A Protobuf file (a2a.proto) when the A2A protocol specification changes. Use when the user mentions updating the spec, syncing with upstream A2A, or when a new version of the A2A protocol is released.

- Skill: `a2aproject/update-a2a-proto` (Agent Skill)
- Install (CLI): `npx skillmds@latest add a2aproject/update-a2a-proto`
- Raw SKILL.md: https://api.skillmd.com/api/skills/a2aproject/update-a2a-proto/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: a2aproject (https://skillmd.com/u/a2aproject)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/a2aproject/update-a2a-proto

---


# Update a2a.proto

Update the A2A gRPC proto file from the upstream specification repository and regenerate Java sources.

## Step 1: Capture the current state

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

1. Read `spec-grpc/src/main/proto/a2a.proto` to note the current commit hash (located at the top of the file in a comment)
2. Save a copy of the file for diffing:

## Step 2: Download the updated specification

1. Ask the user if they want to update from the `main` branch or pass a `tag` or a `commit cheksum`
2. Download the latest `a2a.proto` from the upstream A2A repository at https://github.com/a2aproject/A2A/blob/main/specification/a2a.proto and save it to `spec-grpc/src/main/proto/a2a.proto`.
3. Update the `java_package` option in the downloaded proto file to:
   ```
   option java_package = "org.a2aproject.sdk.grpc";
   ```
4. Update the comment tracking the upstream commit hash (line starting with `// From commit`) to the commit hash / tag of the downloaded proto file.

## Step 3: Analyze specification changes

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

1. Diff `specification/a2a.proto` with the backup to find:
   - New or changed message types
   - New or changed RPC methods
   - New or changed fields

## Step 4: Regenerate gRPC classes

1. Delete all the generated gRPC Java classes (in case of resources removed from the Protobuf definitions):
   ```bash
   find spec-grpc/src/main/java/org/a2aproject/sdk/grpc -maxdepth 1 -name "*.java" -delete```
   ```

2. Regenerate gRPC Java classes by running:
   ```bash
   mvn generate-sources -pl spec-grpc -Dskip.protobuf.generate=false
   ```

## Step 5: Update the code

Based on the spec diff, update the relevant files

Summarize the changes for the user before proceeding.

## Step 6: Validate

Run the tests on all modules to verify the update

```bash
mvn clean install
```

Fix any issues before proceeding.

## Step 7: Audit changes

Before committing, audit all code changes.

Highlight any new, modified, or removed changes in the API in the `client`, `common`, `server-common`, and `spec` modules

Verify the build succeeds for the full project:

```bash
mvn clean install
```

## Step 8: Summarize

Present the user with a summary of:
- The old and new spec commit hashes
- What changed in the specification
- What was updated in the code
- Any areas that need manual review or additional test coverage
- Impact on user API (from the `client`, `common`, `server-common`, and `spec` modules)
  - Write a "migration summary" for breaking changes in the API