[jaeminbird]

Description

A request body that is not valid UTF-8 is reported as a server fault: JSON-RPC answers -32603 Internal Error (logged with a traceback at ERROR), and REST message:send, message:stream and pushNotificationConfigs (v1 and v0.3) answer 500. Malformed JSON already gets -32700 / 400. request.json() and protobuf's Parse(bytes) raise UnicodeDecodeError before any JSON error, so neither path catches it.

The JSON-RPC dispatcher now catches UnicodeDecodeError with JSONDecodeError, and parse_lenient turns invalid UTF-8 bytes into ParseError; the REST handlers use it instead of calling Parse directly (all of them already passed ignore_unknown_fields=True). Valid bodies parse exactly as before.

Not covered: v0.3 message:stream returns an empty 200 stream for any malformed body, including plain bad JSON; that's a separate, existing problem.

• New tests (JSON-RPC, v1 REST x3, v0.3 REST x2, parse_lenient) fail on main and pass with the fix.

• ruff check, ruff format --check, ty check (no new diagnostics), and uv run pytest --cov=src on Linux pass.

• Follow the CONTRIBUTING Guide.

• Make your Pull Request title in the https://www.conventionalcommits.org/ specification.

• Ensure the tests and linter pass

• Appropriate docs were updated (not needed)

[github-actions]

🧪 Code Coverage (vs main)

⬇️ Download Full Report

	Base	PR	Delta
src/a2a/utils/proto_utils.py	95.85%	95.97%	🟢 +0.12%
Total	93.40%	93.40%	⚪️ 0.00%

Generated by coverage-comment.yml

[Iwaniukooo11]

LGTM