fix(server): reject boolean JSON-RPC request IDs

[ningyixi]

Description

JSON-RPC requests with id: true or id: false currently reach the request handler and produce responses containing the same boolean ID. Python's bool satisfies the existing integer check, but JSON-RPC 2.0 distinguishes Boolean from Number and permits only String, Number or Null identifiers.

Reject boolean IDs before dispatch with Invalid Request (-32600) and a null response ID. Add request-level tests for both boolean values and passing controls for integer zero, a positive integer, an empty string and a nonempty string. The invalid requests must not invoke the handler.

• Follow the CONTRIBUTING guide.
• Use a Conventional Commits PR title.
• Ensure tests and linter pass.
• Update appropriate docs if necessary. No documentation change is needed; this enforces the existing JSON-RPC identifier contract.

No existing issue found for boolean request IDs.

Validation:

• On the unchanged base, both boolean regressions fail and all four valid-ID controls pass (initial reproduction on Python 3.12).
• bash scripts/lint.sh: Ruff lint/format and ty pass. ty reports three unused-ignore warnings in unchanged optional gRPC imports.
• uv run pytest: 2,290 passed, 183 skipped, 3 xfailed and 1 xpassed on the repository-pinned Python 3.10.22.
• uv run pytest --cov=src --cov-report=term-missing --cov-fail-under=88: same results; 93.29% coverage, exceeding the 88% requirement.
• git diff --check: passed.

The xfail/xpass cases are marked against #869. Skips include PostgreSQL/MySQL and externally configured multi-server cases. Local HTTP/gRPC and sample integration tests ran as part of the full suite; no live model-provider calls were used.

AI assistance: OpenAI Codex implementation, reproduction and validation.

[github-actions]

🧪 Code Coverage (vs main)

⬇️ Download Full Report

	Base	PR	Delta
src/a2a/server/routes/jsonrpc_dispatcher.py	85.50%	85.71%	🟢 +0.22%
Total	93.14%	93.14%	⚪️ 0.00%

Generated by coverage-comment.yml