feat: Windows support — LLVM/Clang + MSVC STL + full CI pipeline

.agents/docs/2026-05-17-windows-llvm-support-design.md

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+# Windows LLVM/Clang 支持设计方案
+
+Date: 2026-05-17
+
+## 目标
+
+mcpp 在 Windows x86_64 上通过 xmake bootstrap 达到可用水平，产出 mcpp.exe 作为后续自举依赖。
+
+## 平台特征
+
+### Windows LLVM 包（xlings-res 20.1.7）
+
+```
+bin/clang.exe, clang++.exe, clang-cl.exe, lld-link.exe
+bin/llvm-ar.exe, llvm-lib.exe, llvm-rc.exe
+lib/clang/20/lib/windows/clang_rt.*.lib
+没有 libc++（没有 include/c++/v1，没有 std.cppm）
+没有 clang-scan-deps.exe
+```
+
+Windows LLVM 包不含 libc++。Windows 上 clang 搭配 MSVC STL。
+
+### Bootstrap 策略
+
+用 xmake + MSVC（和 xlings 自身做法一致）：
+- GitHub Actions windows-latest 预装 Visual Studio
+- xmake 对 MSVC C++23 modules 支持成熟
+- 不需要额外安装 LLVM（MSVC 即可）
+
+## 代码适配清单
+
+### 必须修改
+
+| 文件 | 问题 | 方案 |
+|------|------|------|
+| ninja_backend.cppm | POSIX shell 命令 | #if _WIN32 cmd.exe 语法 |
+| ninja_backend.cppm | mcpp_exe_path() 缺 Windows | GetModuleFileNameA() |
+| config.cppm | MCPP_HOME 路径发现缺 Windows | 同上 |
+| probe.cppm | command -v Unix only | where.exe |
+| probe.cppm | LD_LIBRARY_PATH | Windows 用 PATH |
+| flags.cppm | 链接 flags 缺 Windows 分支 | 无 sysroot/rpath |
+| xlings.cppm | popen | _popen |
+
+## 执行顺序
+
+1. 创建 ci-windows.yml 用 xmake 构建，看编译错误
+2. 根据 CI 错误逐步修代码
+3. 产出 mcpp.exe bootstrap binary
+4. 上传到 xlings-res

.agents/docs/2026-05-19-pack-windows-design.md

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+# Windows Pack Design
+
+**Date:** 2026-05-19
+**Status:** Planned (stub guard in place, implementation not yet started)
+
+## Current state
+
+`mcpp pack` is fully functional on Linux and macOS. On Windows it exits early
+with a clear error message directing users to the CI workflow:
+
+```
+error: `mcpp pack` is not yet supported on Windows.
+       Use the CI workflow (ci-windows.yml) to produce Windows zip packages.
+       Windows PE packaging (DLL collection + zip) is planned.
+```
+
+The guard lives at the top of `mcpp::pack::run()` in `src/pack/pack.cppm`.
+
+## Why the current implementation cannot run on Windows
+
+The POSIX implementation relies on three Linux/macOS-only mechanisms:
+
+| Mechanism | POSIX usage | Windows equivalent |
+|---|---|---|
+| `LD_TRACE_LOADED_OBJECTS=1` | Tells the ELF dynamic linker to print deps without executing `main()` | No direct equivalent. Would need `dumpbin /dependents` (MSVC) or `ldd` emulation via `LoadLibraryEx` |
+| `patchelf` | Rewrites `RUNPATH` / `PT_INTERP` ELF headers in-place | Not applicable to PE/COFF. DLL search order is controlled by the OS loader and manifest, not embedded paths |
+| `tar -czf` | GNU tar — not universally present on Windows before Win11 22H2 | `Compress-Archive` (PowerShell), `7z`, or Win32 `CreateFile`/`MiniZip` |
+
+## Planned Windows pack implementation
+
+### Goal
+
+Produce a self-contained `.zip` archive (not `.tar.gz`) that users can
+extract and run with no additional setup:
+
+```
+<name>-<version>-x86_64-pc-windows-msvc.zip
+└── <name>-<version>-x86_64-pc-windows-msvc/
+    ├── <name>.exe
+    ├── *.dll         (bundled DLLs, if any)
+    └── README.md / LICENSE (if present)
+```
+
+### DLL discovery
+
+Replace `ldd_parse()` with a Win32 equivalent:
+
+1. **Primary: `dumpbin /dependents <binary>`** — available when MSVC tools are
+   on `PATH`. Produces a list of DLL names; resolve each against `PATH` /
+   `%SystemRoot%\System32` / side-by-side assemblies.
+
+2. **Fallback: `PE header walk`** — open the PE file, walk the Import Directory,
+   extract DLL names.  Can be implemented with `<windows.h>` + `ImageNtHeader`.
+
+3. **Skip-list**: mirror the manylinux skip-list concept for Windows:
+   `kernel32.dll`, `user32.dll`, `ntdll.dll`, `vcruntime*.dll` (Redist),
+   `api-ms-win-*.dll` (API sets), `ucrtbase.dll`.
+
+### Archive creation
+
+Use `std::filesystem` to copy files into a staging directory, then produce
+the zip with one of:
+
+- **PowerShell** `Compress-Archive` — available on all modern Windows.
+  Invoke via `run_capture("powershell -Command \"Compress-Archive ..."`)`.
+  Slow for large trees; fine for typical release packages.
+- **libzip / minizip** — statically linkable; avoid the PowerShell dependency.
+  Preferred long-term.
+
+### Format
+
+- Output file: `.zip` (not `.tar.gz`) on Windows.
+- `pack::Format` enum needs a new `Zip` variant (or auto-select by platform).
+- `make_plan()` should derive the output extension from the target platform.
+
+### Entry point
+
+No shell wrapper needed on Windows — users double-click `<name>.exe` or run
+it from `cmd.exe` / PowerShell directly.  If DLLs are bundled, they should be
+placed in the **same directory** as the executable (the Win32 loader checks
+`%EXE_DIR%` first, before `%PATH%`).
+
+### Implementation checklist (for the future PR)
+
+- [ ] Add `Format::Zip` (or `Format::ZipAuto`) to `pack::Format`
+- [ ] Implement `dumpbin_parse()` (or PE header walk fallback) in `pack.cppm`
+      under `#if defined(_WIN32)`
+- [ ] Implement `make_zip()` (PowerShell or libzip) in `pack.cppm`
+- [ ] Remove the `#if defined(_WIN32)` early-return guard from `pack::run()`
+      once the above are ready
+- [ ] Add a Windows-specific integration test to `ci-windows.yml`
+
+### CI workflow (current workaround)
+
+Until this is implemented, `ci-windows.yml` zips the raw build output with
+PowerShell `Compress-Archive`. This is good enough for CI artifacts but does
+not collect/bundle DLLs or apply the staging-directory layout.

.agents/docs/2026-05-19-windows-e2e-parity-plan.md

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+# Windows E2E 与 macOS 对齐方案
+
+> 目标：Windows E2E 从 20/49 提升到 ~32/49，与 macOS 33/49 对齐。
+
+## 根因分析
+
+| 类别 | 测试数 | 问题 | 修复方式 |
+|------|--------|------|----------|
+| mcpp run/test 单引号 | 1 (02) | `cli.cppm` 用 POSIX 单引号执行 binary | `_WIN32` 改双引号 |
+| clang-scan-deps 查找 | 1 (16) | `cli.cppm` 硬编码无 .exe | 调用已有 `find_scan_deps()` |
+| symlink 依赖 | 4 (10,24,27,32) | `_inherit_toolchain.sh` 用 `ln -sf` | 加 `cp -r` fallback |
+| bash-specific 语法 | 1 (19) | `compgen -G` 不在 Git Bash | 改用 `find` |
+| unix-shell 误标 | 1 (38_mirror) | 实际只需 symlink fallback | 改标签 |
+| import-std-libcxx 硬编码路径 | 4 (37,38,40,41) | 测试用 Linux 路径 | 加 Windows 路径 |
+
+## 修复计划
+
+### Fix 1: cli.cppm 单引号 → 双引号 (解锁 02)
+- `src/cli.cppm:2611` — `mcpp run` 执行 binary 用 `'{}'` → Windows 改 `"{}"`
+- `src/cli.cppm:2522` — fast-path ninja 同上
+- `src/cli.cppm:3159` — test PATH prefix 是 POSIX 语法，Windows 跳过
+
+### Fix 2: clang-scan-deps 查找 (解锁 16)
+- `src/cli.cppm:2162-2167` — 直接查找 `clang-scan-deps`，不走 `find_scan_deps()`
+- 改为调用 `mcpp::toolchain::clang::find_scan_deps(*tc)` 已正确处理 .exe
+
+### Fix 3: _inherit_toolchain.sh cp fallback (解锁 10,24,27,32)
+- 当 `ln -sf` 失败时用 `cp -r` 替代
+- 自动检测 symlink 可用性
+
+### Fix 4: 19_bmi_cache_reuse.sh bash 兼容 (解锁 19)
+- `compgen -G` → `find ... | grep -q .`
+
+### Fix 5: LLVM 测试 Windows 路径 (解锁 37,38,40,41)
+- 参照 36_llvm_toolchain.sh 的模式加 Windows 路径和 .exe 处理
+
+### Fix 6: 标签修正
+- `38_self_config_mirror.sh` 改标签
+- `run_all.sh` 移除已修复测试的标签限制
+
+## 预期结果
+
+修复后：**~32 passed, 0 failed, ~17 skipped** (与 macOS 33 passed 对齐)