github.com/WebKit/WebKit (link)

# Gemini Project Context: libyuv Row Functions

This file provides context for the core row-processing architecture of
libyuv. Use these guidelines when refactoring, reviewing, or generating
code within the `row_*.cc` files.

## Architectural Overview

Libyuv uses a dispatch system where high-level conversion functions call
optimized "Row" functions. These functions are categorized by SIMD architecture
and compiler compatibility.

## Source File Map

### x86 Architectures (32-bit and 64-bit)

*   **row_gcc.

# General workflow

@agents/prompts/common.md @agents/README.md

**Important:** `depot_tools` must be in your `PATH` for working in this checkout
(e.g., for `git new-branch` to work).

# Searching Downstream

When auditing symbol usage or finding references in downstream projects, always
prefer high-precision CodeSearch filters over raw text searches:

-   **Semantic References:** Use `usage:webrtc::SymbolName` to find actual
    call-sites.
-   **Virtual Overrides:** Use `func:MethodName` to find overrides

---
name: checkout-webkit-commit
description: Use when the user wants to checkout a branch, checkout a PR, checkout a commit or move HEAD to a specific commit in the WebKit repository. The user can specify a pull requests by number or URL.
user-invocable: true
allowed-tools: Bash(git-webkit checkout:*), Bash(git webkit checkout:*), Bash(Tools/Scripts/git-webkit checkout:*), Bash(git-webkit find:*), Bash(git webkit find:*), Bash(Tools/Scripts/git-webkit find:*), Bash(git checkout:*),
---

Use `git-webkit che

---
name: hta-reviewer
description: Automated code review following Harald Alvestrand's (hta@) standards for WebRTC. Use this skill to analyze CLs for thread safety, process hygiene, architectural robustness, and modern C++ adoption.
---

# HTA Reviewer Skill

This skill adopts the "Reviewer's Lens" of Harald Alvestrand, a senior WebRTC
engineer. It provides direct, technical, and process-oriented feedback on code
changes.

## Core Mandates

### 1. Process Hygiene

- **Freshness**: Ensure the CL is rebased 

---
name: update-pregenerated-files
description: How to regenerate/update pre-generated files (e.g., perlasm, build files) in BoringSSL.
---

# Regenerating Pre-generated Files

BoringSSL checks in a number of pre-generated build artifacts. If you modify any inputs to these files, they must be regenerated.

To regenerate these files, refer to the following documentation:

*   [gen/README.md](../../../gen/README.md) - Instructions on how to run the pregenerate tool, check if files are up-to-date, and filter 

---
name: add-error-code
description: How to add a new error code in BoringSSL.
---

# Adding a New Error Code

To add a new error code, you only need to use it in the source code and then run the error generation script. The script will automatically define it in the header and update the error database.

## Steps

1.  **Use the Error Code**:
    *   Use the new error code directly in your C/C++ source file (e.g., `EVP_R_NEW_ERROR_CODE`). It must start with the correct library prefix (e.g., `EVP_R_`, `SSL_

---
name: find-webkit-commit
description: Auto-invoke (1) to convert git commit hashes to WebKit identifiers (NNNNNN@main) and (2) to convert identifiers to commit hashes using git-webkit. Use whenever a commit hash appears in a tool result that will be shared with the user in the WebKit repository.
user-invocable: false
allowed-tools: Bash(git-webkit find:*), Bash(git webkit find:*), Bash(Tools/Scripts/git-webkit find:*), Bash(git-webkit log:*), Bash(git webkit log:*), Bash(Tools/Scripts/git-webkit log:*),

---
name: api-compat-reviewer
description: Automated code review for backward-incompatible changes in WebRTC public headers. Use this skill to catch renames/removals/signature changes in api/ (and other downstream-consumed headers like pc/session_description.h) that will break Chromium and internal builds, and to verify a deprecation polyfill is in place.
---

# API Compat Reviewer Skill

libWebRTC is consumed by downstream projects (Chromium, and internal,
closed-source Google code) that build out-of-tree 

---
name: add-object-nid-oid
description: How to add a new object with a NID and/or OID to BoringSSL.
---

# Adding a New NID or OID

To add a new ASN.1 object (with a NID and/or OID) to BoringSSL, you must add it to the objects definition file and regenerate the generated headers and lookup tables.

Refer to [crypto/obj/README.md](../../../crypto/obj/README.md) for an overview of the generated files.

## Steps

1.  **Update `objects.txt`**:
    *   Add the new object to [crypto/obj/objects.txt](../../../cr

---
name: gtest-parallel
description: Run Google Test binaries in parallel using the gtest-parallel script. Use when needing to speed up test execution, run flaky tests with repeat, or filter specific tests.
---

# gtest-parallel

`gtest-parallel` is a script that executes Google Test binaries in parallel,
providing speedup for single-threaded tests and tests that do not run at 100%
CPU.

## Location

The script is located at `third_party/gtest-parallel/gtest-parallel`.

## Core Flags

### Filtering Tests

---
name: include-cleaner
description: Runs the WebRTC include-cleaner tool (IWYU replacement) to fix headers in C++ files. Use when preparing a CL for upload, after modifying .cc or .h files, or when instructed to fix include regressions.
---

# WebRTC Include Cleaner

This skill provides instructions for using
`tools_webrtc/iwyu/apply-include-cleaner`, a tool that automatically manages C++
`#include` directives in the WebRTC codebase. It ensures that every header used
is explicitly included and that unuse

---
name: reduce-header-includes
description: Use when the user wants to remove unused #include directives from a WebKit source directory (bmalloc, WTF, JavaScriptCore, WebCore, WebKit) to reduce build time. Runs clang-include-cleaner with WebKit-specific false-positive filters, ranks headers by ninja-deps fan-out, and fixes transitive breakage in a -k 0 loop.
user-invocable: true
allowed-tools: Bash, Read, Edit, Write, Agent
---

## 1. One-time setup

```sh
brew install llvm                         # → /

---
name: webrtc-changelog
description: Generate a professional HTML changelog from WebRTC git logs. Automatically categorizes changes, includes a high-level summary, and provides detailed commit and review links.
---

# WebRTC Changelog Generator

`webrtc-changelog` automates the generation of a professional, categorized HTML
report for WebRTC changes.

## Workflow

1. **Fetch Branch Information:** Navigate to
   `https://chromiumdash.appspot.com/branches` and extract the current and
   previous branch num

---
name: classify-webkit-commit
description: Use when the user wants to classify a commit or understand what kind of change a commit represents in the WebKit repository.
user-invocable: true
allowed-tools: Bash(git-webkit classify:*), Bash(git webkit classify:*), Bash(Tools/Scripts/git-webkit classify:*), Bash(git-webkit find:*), Bash(git webkit find:*), Bash(Tools/Scripts/git-webkit find:*)
---

Use `git-webkit classify` to compute the classification of a given commit.

## How to use

```
git-webkit class

---
name: skia-add-test
description: Add a new test to the Skia repository. Use this skill when you need to create a new unit or integration test in the tests/ directory and ensure it's part of the build system.
---

# Skia Add Test Skill

This skill guides you through adding a new test to Skia. Tests are primarily written in C++ and located in the `tests/` directory.

## Workflow

### 1. Create the Test File
Create a new `.cpp` file in the `tests/` directory. Use the provided template as a starting point.

---
name: add-source-file
description: How to add a new source file to the BoringSSL build.
---

# Adding a Source File to the Build

To add a new source file (C/C++, header, or assembly) to BoringSSL, you must update the build configuration and regenerate the build files.

## Steps

1.  **Update `build.json`**:
    *   Add the new file to the correct section (e.g., `srcs`, `hdrs`, `internal_hdrs`) under the appropriate target in [build.json](../../../build.json).
    *   For the schema of `build.json`, ref

---
name: build-and-test
description: How to build BoringSSL and run its tests.
---

# Building and Testing BoringSSL

To build BoringSSL and run its tests, you must refer to the official documentation in the repository.

1. Read [BUILDING.md](../../../BUILDING.md) to understand the prerequisites, build steps (using CMake and Ninja), and how to run the test suite.
2. Follow the instructions in that file for the target platform.

---
name: gn-check-autofix
description: Automatically fix GN check errors in WebRTC BUILD.gn files. Use when encountering "Include not allowed", "rtc_source_set shall not contain cc files", or when needing to clean up non-absolute dependencies.
---

# GN Check Autofix

This skill provides instructions for using `tools_webrtc/gn_check_autofix.py` to
automatically resolve common GN build configuration errors in WebRTC.

## Core Workflows

### Fix Missing Dependencies

When you see "Include not allowed" errors

---
name: git-cl
description: Provides commands for interacting with Gerrit CLs using git cl, including issue management and non-interactive uploads.
---

# git cl Skill

This skill provides instructions and best practices for using `git cl` in WebRTC
development.

## Available Workflows

- **Uploading Changes**: For non-interactive uploads, handling chained branches,
  and presubmit warnings, see [references/upload.md](references/upload.md).

## Future Extensions

This skill can be extended to cover:

- `g

---
name: run-ssl-go-tests
description: How to run BoringSSL's ssl/test/runner suite (protocol-level BoGo tests)
---

# Running BoringSSL Protocol-Level Tests (BoGo Tests aka blackbox tests)

This skill describes how to run and configure BoringSSL's protocol-level test suite, which uses a Go-based test harness (`runner`) and a C++ shim (`bssl_shim`).

To run and work with these tests, you must refer to the following documentation:

1.  **Overview and Running**: Read [ssl/test/README.md](../../../ssl/test/RE

---
name: update-webkit
description: Use when the user wants to update, pull, or sync their WebKit repository or branch.
user-invocable: true
allowed-tools: Bash(git-webkit pull:*), Bash(git webkit pull:*), Bash(Tools/Scripts/git-webkit pull:*), Bash(git-webkit find:*), Bash(git webkit find:*), Bash(Tools/Scripts/git-webkit find:*)
---

Use `git-webkit pull` to update the current repository.

## What it does

- Updates the current production branch (e.g., `main`) with the latest upstream changes
- If on a d

---
name: pre-reviewer
description: Automated pre-review tool to inspect C++ style, concurrency safety, test quality, and CL descriptions before submitting code for human review.
---

<!-- go/cmark -->

<!--* freshness: {owner: 'tommi' reviewed: '2026-06-12'} *-->

# Pre-Reviewer Skill

This skill acts as a pre-review confidence check tool for WebRTC C++
contributions. Use this skill to evaluate code changes for common C++
anti-patterns, concurrency bugs, test hygiene issues, and CL description
completeness

---
name: skia-gn-workflow
description: MANDATORY: Use this skill for ANY and ALL tasks involving building Skia with GN, Ninja, or compiling any Skia tool. It is the authoritative source for Skia's build workflows and MUST be used whenever compilation is required.
---

# skia-gn-workflow

This skill provides expert guidance for building and testing Skia using the GN build system and Ninja. It covers common workflows for correctness testing (`dm`), performance benchmarking (`nanobench`), and interactive visu

@README.md

@README.md