[mgradwohl]

Description

CodeQL alert #3900 (cpp/poorly-documented-function) flags Broker::encodeRequest. It was one 103-line if/else if chain over every request kind, and passed 100 lines with protocol v6 and v7 (#2972, #3002). encodeResponse was 248 lines of the same shape, kept under the alert only by its comments.

As #2526 did for the decoders, each message kind now has its own short, documented Detail::encodePayload(Writer&, const T&) overload. It writes that kind's payload and returns its MessageKind. encodeRequest/encodeResponse are now a std::visit over those overloads.

• The bytes written are unchanged. Each overload is the old branch, moved as is, and the protocol version is unchanged.
• A new message kind without an encoder no longer compiles. The old chain silently fell through to MessageKind::Hello/HelloReply with an empty payload.

Fixes #3043

PR Size

Medium in lines (+403/−342, one header), but each block is a branch moved into its own function.

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update
• Build/CI improvement

Refactor, with no behaviour change.

Checklist

• I have read the CONTRIBUTING guidelines
• My code follows the project's coding standards
• I have run clang-tidy and addressed any warnings
• I have run clang-format on my changes
• I have run pre-commit run --all-files or installed pre-commit hooks
• I have added tests that prove my fix/feature works
• All new and existing tests pass
• I have updated documentation as needed

No new tests: the decoders are unchanged, and test_BrokerProtocol.cpp's round trips cover every message kind, so the encoders are checked against them. The helper tests run each request end to end.

Testing

cmake --build --preset debug -j 4
build/debug/tests/TaskSmackTests --gtest_filter='Broker*:PkexecBroker*:*Helper*'   # 335 passed
TASKSMACK_REQUIRE_DISPLAY=1 TASKSMACK_REQUIRE_SDBUS=1 xvfb-run -a env -u WAYLAND_DISPLAY ctest --preset debug -j 4   # 689/689
clang-tidy-22 -p build/debug --header-filter="^$PWD/src/" src/Platform/BrokerRequestMapping.cpp   # clean in BrokerProtocol.h

Additional Notes

Main only, no backport: no wire change, and v0.9.x's protocol code stays as it shipped.

🤖 Generated with Claude Code

[github-actions]

Dependency Review

✅ No vulnerabilities or license issues or OpenSSF Scorecard issues found.

Scanned Files

None