clang-format in CI

.clang-format

@@ -0,0 +1,10 @@
+---
+BasedOnStyle: Google
+Language: Cpp
+Standard: c++17
+
+# LiveKit modifications to Google style below
+
+ColumnLimit: 120                  # more width on modern screens
+SpacesBeforeTrailingComments: 1   # one space for trailing namespace comments, e.g. `} // namespace foo` (Google uses 2)
+AccessModifierOffset: -2          # left-align public/protected/private with the class keyword (Google indents by 1)

.github/workflows/builds.yml

@@ -17,6 +17,8 @@ on:
       - docker/Dockerfile.base
       - docker/Dockerfile.sdk
       - .github/workflows/**
+      - .clang-format
+      - scripts/clang-format.sh
   pull_request:
     branches: ["main"]
     paths:
@@ -33,6 +35,8 @@ on:
       - docker/Dockerfile.base
       - docker/Dockerfile.sdk
       - .github/workflows/**
+      - .clang-format
+      - scripts/clang-format.sh
   workflow_dispatch:
 
 permissions:
@@ -513,6 +517,42 @@ jobs:
             cmake --build build --parallel
           '
 
+  clang-format:
+    name: clang-format
+    runs-on: ubuntu-latest
+    continue-on-error: false
+    permissions:
+      contents: read
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+        with:
+          # No submodules: scripts/clang-format.sh only walks our own src/ tree
+          fetch-depth: 1
+
+      - name: Install clang-format 22
+        run: |
+          set -eux
+          # Pin clang-format 22 to match the current macOS Homebrew LLVM
+          # Ubuntu 24.04's default clang-format ships with LLVM 18
+          sudo install -m 0755 -d /etc/apt/keyrings
+          wget -qO- https://apt.llvm.org/llvm-snapshot.gpg.key \
+            | sudo tee /etc/apt/keyrings/llvm.asc >/dev/null
+          sudo chmod a+r /etc/apt/keyrings/llvm.asc
+          codename=$(lsb_release -cs)
+          echo "deb [signed-by=/etc/apt/keyrings/llvm.asc] http://apt.llvm.org/${codename}/ llvm-toolchain-${codename}-22 main" \
+            | sudo tee /etc/apt/sources.list.d/llvm-22.list >/dev/null
+          sudo apt-get update
+          sudo apt-get install -y clang-format-22
+          sudo ln -sf /usr/bin/clang-format-22 /usr/local/bin/clang-format
+          clang-format --version
+
+      - name: Run clang-format
+        env:
+          FORMAT_BLOB_SHA: ${{ github.event.pull_request.head.sha || github.sha }}
+        run: ./scripts/clang-format.sh
+
   clang-tidy:
     name: clang-tidy
     runs-on: ubuntu-latest

AGENTS.md

@@ -169,8 +169,10 @@ All source files must have the LiveKit Apache 2.0 copyright header. Use the curr
 ### Readability and Performance
 Code should be easy to read and understand. If a sacrifice is made for performance or readability, it should be documented.
 
+Adhere to clang-format checks configured in `.clang-format`. Run `./scripts/clang-format.sh` if needed to confirm code styling.
+
 ### Static Analysis
-Adhere to clang-tidy checks configured in `.clang-tidy`.
+Adhere to clang-tidy checks configured in `.clang-tidy`. Run `./scripts/clang-tidy.sh` if needed to confirm code quality.
 
 ## Dependencies
 

README.md

@@ -521,9 +521,9 @@ This SDK leverages various tools and checks to ensure the highest quality of the
 ### Clang Tools
 
 - `clang-tidy`: static analysis checks to catch common C++ pitfalls. See [.clang-tidy](./.clang-tidy) for the list of current checks (enforced in CI on PR)
-- `clang-format`: (coming soon) code formatting and style consistency
+- `clang-format`: code formatting and style consistency. See [.clang-format](./.clang-format) for the list of style configurations (enforced in CI on PR)
 
-> **Note**: clang-tidy is not currently supported on Windows for this project because the Visual Studio CMake generator does not produce the compile_commands.json database that clang-tidy requires.
+> **Note**: For Windows, `clang-tidy` is not currently supported for this project because the Visual Studio CMake generator does not produce the compile_commands.json database that `clang-tidy` requires. Similarly, `clang-format` must be installed and run manually on Windows, referencing the root `.clang-format` file.
 
 To run locally, first install the following:
 
@@ -542,7 +542,13 @@ This installs `clang-format`, `clang-tidy`, and `run-clang-tidy`. Homebrew may a
 sudo apt-get install clang-format clang-tidy clang-tools
 ```
 
-To run:
+**Pre-commit hook**
+
+```bash
+printf '#!/bin/sh\nFILES=$(git diff --cached --name-only --diff-filter=ACMR -- "*.c" "*.cc" "*.cpp" "*.cxx" "*.h" "*.hpp" "*.hxx")\n[ -z "$FILES" ] && exit 0\necho "$FILES" | xargs ./scripts/clang-format.sh --fix\necho "$FILES" | xargs git add\n' > .git/hooks/pre-commit && chmod +x .git/hooks/pre-commit
+```
+
+To run `clang-tidy`:
 
 1. Generate `compile_commands.json` and the protobuf headers via a release build:
 
@@ -566,6 +572,24 @@ The wrapper forwards extra arguments to `run-clang-tidy`, examples below:
 
 Output is captured to `clang-tidy.log` at the repo root. This is done as a convenience feature, as often times the terminal buffer is not large enough for all the output.
 
+To run `clang-format`:
+
+```bash
+./scripts/clang-format.sh
+```
+
+With no arguments, runs `clang-format` against every relevant file in the repository against defined `.clang-format` rules.
+
+Pass flags or paths as needed, examples below:
+
+```bash
+./scripts/clang-format.sh --fix                                # Rewrite files in place
+./scripts/clang-format.sh src/room.cpp include/livekit/room.h  # Check just these files
+./scripts/clang-format.sh --fix src/room.cpp                   # Fix just this file
+```
+
+Output is captured to `clang-format.log` at the repo root.
+
 ### Memory Checks
 
 Run valgrind on various examples or tests to check for memory leaks and other issues.