Add pkg-config and CMake C smoke cells

[kixelated]

What

Adds two new C subscriber cells to the smoke matrix — c-pkgconfig and c-cmake — alongside the existing c. All three build the same subscribe-only clients/c/subscribe.c against the same prebuilt libmoq tarball; they differ only in how the build discovers the library:

Cell	How it links	Catches
c	hand-rolled -I/-L/-l (unchanged)	does the static archive link at all
c-pkgconfig	pkg-config --cflags --static --libs moq	wrong includedir/libdir or a missing framework in moq.pc
c-cmake	find_package(moq) → moq::moq	broken lib/cmake/moq package config

This mirrors the existing js-vite/js-esbuild/js-jsdelivr "same client, different delivery" pattern.

Why

The C client hand-links libmoq with its own -I/-L/-l flags and hardcoded system libs, so it never reads the lib/pkgconfig/moq.pc or lib/cmake/moq/ files that the release tarball also ships. That leaves a whole class of packaging breakage invisible to the smoke test — e.g. a wrong includedir/libdir or a missing -framework CoreServices in moq.pc, the kind of thing moq#1758 fixed. Those are the FFmpeg --enable-libmoq / CMake-consumer paths the harness had no equivalent of.

The --static flag on the pkg-config build is the key bit: libmoq is a static archive, so --static pulls in Libs.private (the system frameworks/libs), meaning a missing framework genuinely fails the build.

Notes for reviewers

• c_prepare is split into a shared, idempotent libmoq_fetch (one download for all three variants) plus c_build_direct / c_build_pkgconfig / c_build_cmake. Each variant fails only its own cell; a failed download marks all three broken (same as the js group).
• New clients/c/CMakeLists.txt is driven by c_build_cmake (CMAKE_PREFIX_PATH → tarball root); it's not meant to be built standalone.
• CI: added pkg-config + cmake to the Linux and macOS dep installs, and c-pkgconfig,c-cmake to the matrix + the just full recipe.
• Still tests the nix-relocated tarball layout (what releases ship), not the raw cargo build target tree where moq#1758's path bug actually lived. Closing that gap would mean building libmoq from source in the harness — a bigger change, arguably outside this repo's "test the public packages" charter. Flagging as a possible follow-up.

Verification

• bash -n smoke.sh clean.
• Live run on macOS (libmoq-v0.3.5, aarch64): rust → c,c-pkgconfig,c-cmake all PASS.
• Couldn't run shellcheck/shfmt locally (not installed); CI's just check will lint.

[coderabbitai]

Warning

Review limit reached

@kixelated, we couldn't start this review because you've reached your PR review rate limit.

More reviews will be available in 49 minutes and 6 seconds. Learn how PR review limits work.

Your organization has used up its prepaid credits, and credit purchases are no longer available. Enable the review add-on in the billing tab to keep reviews running — you're only billed for reviews past your plan's rate limits ($0.25/file).

⌛ How to resolve this issue?

After more reviews become available, a review can be triggered using the @coderabbitai review command as a PR comment. Alternatively, push new commits to this PR.

We recommend that you space out your commits to avoid hitting the rate limit.

🚦 How do rate limits work?

CodeRabbit enforces hourly rate limits for each developer per organization.

Our paid plans include higher PR review limits than trial, open-source, and free plans. In all cases, reviews become available again over time. During sustained high-volume PR review activity, CodeRabbit may temporarily slow when the next review becomes available.

Please see our Fair Usage Limits Policy for further information.

ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: a6f19e42-d223-423e-ad48-68e7489e0c18

📥 Commits

Reviewing files that changed from the base of the PR and between d735bc0 and a688f20.

📒 Files selected for processing (4)

• .editorconfig
• freshness.sh
• justfile
• smoke.sh

Walkthrough

The PR expands C smoke-test coverage from one build variant to three. A new libmoq_fetch function replaces the old c_prepare, downloading the prebuilt libmoq release once and exposing LIBMOQ_ROOT and LIBMOQ_OS_LIBS. Three independent build functions (c_build_direct, c_build_pkgconfig, c_build_cmake) each compile subscribe.c using a different linkage method, producing separate binaries (C_SMOKE, C_PC_SMOKE, C_CMAKE_SMOKE). A new clients/c/CMakeLists.txt supports the CMake variant via find_package(moq). The subscriber dispatch and CI matrix are updated to include all three C variants, and the justfile full recipe gains js-native-node and js-native-bun subscribers.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the main change: adding pkg-config and CMake C smoke cells to the test matrix.
Description check	✅ Passed	The description comprehensively documents the what, why, and how of the changes, including motivation for catching packaging breakage and detailed implementation notes.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

✨ Simplify code

• Create PR with simplified code
• Commit simplified code in branch claude/quirky-cori-bcbf20

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands and usage tips.}