[politerealism]

Summary

Make the protobuf build scripts honor PROTOC. The openshell-core, openshell-server and openshell-sandbox-backend build scripts always used the vendored protoc binary and ignored PROTOC, so a distro build could not use its system compiler (#3510, item 10).

Related Issue

Contributes to #3510

Changes

• crates/openshell-core/build.rs, crates/openshell-server/build.rs, crates/openshell-sandbox-backend/build.rs: when PROTOC is set, use it and let prost resolve the well-known includes (PROTOC_INCLUDE still applies). When PROTOC is unset, behavior is unchanged: the vendored compiler and include tree are used, along with the existing re-entry that removes PROTOC_INCLUDE.
• Emit cargo:rerun-if-env-changed for PROTOC and PROTOC_INCLUDE so switching modes rebuilds.

All protos in the repo are plain proto3 and import only google/protobuf/{descriptor,duration,struct,timestamp}.proto.

Testing

Checked with Fedora 44's protoc 3.19.6 (protobuf-compiler and protobuf-devel), using cargo check on the three crates:

• Nothing set (default, vendored): cargo clippy --all-targets -- -D warnings passes.
• PROTOC and PROTOC_INCLUDE set to the Fedora files: builds.
• PROTOC set, PROTOC_INCLUDE unset (protoc finds its own includes): builds.
• Only PROTOC_INCLUDE set (vendored mode, existing workaround path): builds.
• PROTOC=/nonexistent/protoc: fails with prost's "Could not find protoc", confirming the variable is honored and the vendored binary is not used silently.
• cargo fmt --all -- --check passes.
• Not tested: a full rpmbuild using this, or the unit test suite.
• Open question, deliberately out of scope: the protoc-bin-vendored* crates ship prebuilt protoc binaries in the vendored source tree, which a distro build may still need to remove or avoid. A default-on cargo feature could address that if Fedora review requires it.

Checklist

• Follows Conventional Commits
• Commits are signed off (DCO)
• Architecture docs updated (if applicable): not applicable

[copy-pr-bot]

This pull request requires additional validation before any workflows can run on NVIDIA's runners.

Pull request vetters can view their responsibilities here.

Contributors can view more details about this message here.

[pimlock]

/ok to test b1ba429

[purp]

/ok to test b1ba429