chore: cleanup stale files and update documentation

- Remove openspec workflow files and AGENTS.md
- Consolidate AI guidance into CLAUDE.md
- Update bilingual documentation
- Add CHANGELOG.md

Author: LessUp

.github/copilot-instructions.md

@@ -0,0 +1,29 @@
+# Changelog
+
+All notable changes to this project will be documented in this file.
+
+## [1.3.0] - 2025-05
+
+### Added
+- Runtime SIMD dispatch module with AVX-512/AVX2/SSE2 fallback (`include/hpc/simd.hpp`)
+- Header-only safety hardening across all modules
+- Benchmark comparison tool with Markdown report generation (`tools/performance/benchmark_compare.py`)
+
+### Changed
+- VitePress documentation redesign with Quantum Cobalt theme
+- Bilingual homepage landing flow improvements
+- Consolidated AI guidance into single `CLAUDE.md` file
+- Removed OpenSpec workflow for simplified maintenance
+
+## [1.0.0] - 2024
+
+### Added
+- Initial project structure with CMake preset-driven builds
+- Memory and cache optimization examples (AOS/SOA, false sharing, alignment, prefetch)
+- Modern C++ performance patterns (constexpr, move semantics, ranges)
+- SIMD vectorization examples (auto-vectorization, SSE/AVX intrinsics)
+- Concurrency examples (atomics, lock-free queue, OpenMP)
+- VitePress bilingual documentation site (English + Chinese)
+- Google Test and RapidCheck testing frameworks
+- Google Benchmark integration
+- Sanitizer presets (ASAN, TSAN, UBSAN)

AGENTS.md

@@ -1,25 +1,8 @@
 # CLAUDE.md
 
-## Mission
-
-Help finish this repository cleanly. Prioritize hardening, consistency, and removal of stale surfaces over feature expansion.
-
 ## Project position
 
-This repository is in **closure and hardening mode** (archive-ready for low-frequency maintenance).
-
-## Working style
-
-1. Read the relevant capability specs in `openspec/specs/`.
-2. Work inside an OpenSpec change under `openspec/changes/`.
-3. Prefer aggressive cleanup when a file or workflow is stale, duplicated, or no longer part of the final repo story.
-4. Keep user-facing guidance aligned across:
-   - `README.md`
-   - `README.zh-CN.md`
-   - `docs/`
-   - `AGENTS.md`
-   - `.github/copilot-instructions.md`
-5. Use `/review` before merge or after a large cleanup phase.
+This repository is in **closure and hardening mode** (archive-ready for low-frequency maintenance). Prefer normalization, defect fixing, and removal of stale or low-signal surfaces over adding new features.
 
 ## C++ Standards and Style
 
@@ -28,16 +11,26 @@ This repository is in **closure and hardening mode** (archive-ready for low-freq
 - **Memory safety**: prefer RAII, smart pointers, avoid raw `new/delete`
 - **Performance**: always measure with benchmarks before claiming improvement
 - **Concurrency**: use `std::atomic` with explicit memory ordering
+- **Header-only design**: all library code in `include/hpc/` and `examples/*/include/` is header-only. Platform-specific code is hidden behind preprocessor conditionals within headers.
+
+## Repository layout
+
+```text
+cpp-high-performance-guide/
+├── CMakeLists.txt
+├── CMakePresets.json
+├── cmake/
+├── examples/
+├── tests/
+├── benchmarks/
+├── tools/
+├── scripts/
+├── docs/                  # VitePress site and bilingual learning docs
+├── .githooks/             # Project-managed Git hooks
+└── .github/
+```
 
-## Project facts
-
-- Docs stack: **VitePress**, published via GitHub Pages
-- Build system: **CMake + presets**
-- Language server: **clangd** — configured via `.clangd` at repo root (`CompilationDatabase: build/debug`); all CMake presets export `compile_commands.json` via `CMAKE_EXPORT_COMPILE_COMMANDS=ON`
-- Primary maintenance target: **Linux**
-- Repo posture: **archive-ready / low-frequency maintenance**
-
-## Commands
+## Standard commands
 
 ```bash
 # Build and test
@@ -58,9 +51,30 @@ cmake --preset=release && cmake --build build/release
 ./scripts/setup-hooks.sh
 ```
 
-## Process expectations
+## Engineering rules
+
+- Prefer **deleting or archiving stale content** instead of preserving redundant surfaces.
+- Keep **README** focused on repository entry and onboarding; use the docs site for the richer narrative.
+- Treat **GitHub Pages** as a project landing page, not a thin README mirror.
+- Keep user-facing documentation **English + Chinese** where the surface is meant to be bilingual.
+- Use **CMake presets** as the default build and test entry points.
+- Keep workflows **preset-driven, low-noise, and meaningful**.
+- Avoid over-engineering with extra plugins, MCP servers, or automation layers unless they clearly reduce maintenance cost.
+
+## AI tooling policy
+
+- **CLAUDE.md**: Claude Code specific guidance (this file).
+- **LSP**: prefer `clangd` backed by `compile_commands.json`. The `.clangd` config at the repo root points `CompilationDatabase` to `build/debug`.
+- **Review model**: use `/review` before merge or after major cleanup phases.
+
+## Editor integration
+
+The `.vscode/` directory is **gitignored**. Use `.clangd`, `.editorconfig`, and `CMakePresets.json` for machine-readable project conventions.
+
+## Things to avoid reintroducing
 
-- Do not add new generic documentation just to fill space.
-- Do not reintroduce GitBook / HonKit / `.kiro` assumptions.
-- Keep workflows meaningful; delete low-value automation rather than preserving it.
-- Prefer one long-running implementation session to quota-heavy parallelism unless the work clearly benefits from it.
+- HonKit / GitBook-era configuration
+- `.kiro/`-style legacy spec structures
+- duplicate changelog surfaces with no maintenance value
+- non-blocking CI steps that hide real failures
+- generic AI instructions that do not reflect this repository

CHANGELOG.md

@@ -18,13 +18,9 @@ ctest --preset=debug
 
 ## Default workflow
 
-1. Read the relevant capability specs in `openspec/specs/`.
-2. Create or update one change under `openspec/changes/<change-id>/`.
-3. Implement tasks in dependency order.
-4. Keep docs, specs, and code in sync.
-5. Run the required validation commands.
-6. Use `/review` before merge for non-trivial work.
-7. Archive the change after completion.
+1. Keep docs and code in sync.
+2. Run the required validation commands.
+3. Use `/review` before merge for non-trivial work.
 
 ## Validation commands
 
@@ -69,9 +65,4 @@ The repository hooks currently enforce:
 
 ## Need the AI workflow?
 
-See:
-
-- `AGENTS.md`
-- `CLAUDE.md`
-- `.github/copilot-instructions.md`
-- `docs/en/contributing/ai-workflow.md`
+See `CLAUDE.md` for Claude Code specific guidance.

CLAUDE.md

@@ -18,13 +18,9 @@ ctest --preset=debug
 
 ## 默认开发流程
 
-1. 先阅读 `openspec/specs/` 中相关的 capability spec。
-2. 在 `openspec/changes/<change-id>/` 下创建或更新一个 change。
-3. 按任务依赖顺序实施。
-4. 保持 docs、specs 与代码同步。
-5. 运行要求的验证命令。
-6. 对非 trivial 修改在合并前使用 `/review`。
-7. 完成后归档该 change。
+1. 保持文档与代码同步。
+2. 运行要求的验证命令。
+3. 对非 trivial 修改在合并前使用 `/review`。
 
 ## 验证命令
 
@@ -69,9 +65,4 @@ cmake --preset=ubsan && cmake --build build/ubsan && ctest --preset=ubsan
 
 ## 如果你需要 AI 开发流程
 
-参见：
-
-- `AGENTS.md`
-- `CLAUDE.md`
-- `.github/copilot-instructions.md`
-- `docs/zh/contributing/ai-workflow.md`
+参见 `CLAUDE.md`。

CONTRIBUTING.md

@@ -43,7 +43,6 @@ Every major topic is meant to be **readable, buildable, and measurable**.
 | `examples/04-simd-vectorization/` | auto-vectorization, intrinsics, SIMD wrappers |
 | `examples/05-concurrency/` | atomics, lock-free queue, OpenMP |
 | `docs/` | bilingual Pages whitepaper covering academy, architecture, playbook, reference, research |
-| `openspec/` | spec-driven development workflow and change history |
 
 ## Quick start
 
@@ -89,23 +88,6 @@ cmake --preset=ubsan && cmake --build build/ubsan && ctest --preset=ubsan
 - **Validation & sanitizers:** [`docs/en/guides/validation.md`](docs/en/guides/validation.md)
 - **Chinese entry:** `README.zh-CN.md` and `docs/zh/`
 
-## Development workflow
-
-This repository uses **OpenSpec** for non-trivial changes.
-
-1. Read the affected capability specs in `openspec/specs/`.
-2. Create or update a change under `openspec/changes/<change-id>/`.
-3. Implement tasks in dependency order.
-4. Run preset-driven validation.
-5. Use `/review` before merge for non-trivial work.
-6. Archive completed changes.
-
-The repository also keeps AI tool guidance in:
-
-- `AGENTS.md`
-- `CLAUDE.md`
-- `.github/copilot-instructions.md`
-
 ## Tech stack
 
 - **Language:** C++20

CONTRIBUTING.zh.md

@@ -43,7 +43,6 @@
 | `examples/04-simd-vectorization/` | 自动向量化、intrinsics、SIMD 封装 |
 | `examples/05-concurrency/` | 原子操作、无锁队列、OpenMP |
 | `docs/` | 双语 Pages 白皮书，覆盖学院 / 架构 / 实践手册 / 参考 / 研究 |
-| `openspec/` | 规格驱动开发流程与 change 历史 |
 
 ## 快速开始
 
@@ -90,23 +89,6 @@ cmake --preset=ubsan && cmake --build build/ubsan && ctest --preset=ubsan
 - **验证与 Sanitizer：** [`docs/zh/guides/validation.md`](docs/zh/guides/validation.md)
 - **英文入口：** `README.md` 与 `docs/en/`
 
-## 开发流程
-
-本仓库对非 trivial 修改使用 **OpenSpec**：
-
-1. 先阅读 `openspec/specs/` 中受影响的 capability spec。
-2. 在 `openspec/changes/<change-id>/` 下创建或更新一个 change。
-3. 按任务依赖顺序实施。
-4. 使用 preset 驱动的命令做验证。
-5. 非 trivial 修改在合并前使用 `/review`。
-6. 完成后归档 change。
-
-仓库也为 AI 工具保留了明确说明：
-
-- `AGENTS.md`
-- `CLAUDE.md`
-- `.github/copilot-instructions.md`
-
 ## 技术栈
 
 - **语言：** C++20