add mcpplibs-capi-lua library & refactor tests

- Add mcpplibs-capi-lua package (C++23 module bindings for Lua 5.4 C API)
- Add test for mcpplibs-capi-lua
- Refactor tests: top-level tests/xmake.lua with local repo path,
  remove duplicated add_repositories from each test
- Add mcpplibs-index-add skill for library onboarding workflow

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: Sunrisepeak

.agents/skills/mcpplibs-index-add.md

@@ -0,0 +1,156 @@
+---
+name: mcpplibs-index-add
+description: Add a new C++ library to the mcpplibs-index xmake package repository. Use when user provides a GitHub repo URL and wants to add it as a package.
+---
+
+# Add Library to mcpplibs-index
+
+## Overview
+
+This skill adds a new library from `https://github.com/mcpplibs/<name>` to the mcpplibs-index xmake package repository. The full workflow: gather info → create package definition → create test → verify build → commit & push.
+
+## References
+
+- xmake package docs: https://xmake.io/mirror/manual/package_dependencies.html
+- mcpplibs org: https://github.com/mcpplibs
+- index repo: https://github.com/mcpplibs/mcpplibs-index
+
+## Step 1: Gather Library Info
+
+From the given GitHub repo URL, collect:
+
+1. **Repo description** — from GitHub page
+2. **License** — typically Apache-2.0
+3. **Latest release tag** — e.g. `0.0.1`
+4. **Target name** — from the repo's `xmake.lua` (`target("xxx")`)
+5. **Module name** — from `.cppm` files (`export module xxx`)
+6. **Namespace** — from `.cppm` files (`export namespace xxx`)
+7. **Dependencies** — from `add_requires()` in the repo's `xmake.lua`
+8. **Extra headers** — any `.h` files referenced in `.cppm` that need manual install (e.g. `#include "xxx.h"` in module preamble)
+9. **SHA256 of release tarball**:
+
+```bash
+curl -sL https://github.com/mcpplibs/<name>/archive/refs/tags/<version>.tar.gz | sha256sum
+```
+
+## Step 2: Determine Package Name
+
+**Critical rule**: The package directory name MUST match the `package("xxx")` name exactly.
+
+- If the target name is generic (e.g. same as an existing xmake package like `lua`), use a prefixed name like `mcpplibs-capi-lua` to avoid conflicts
+- If the target name is unique (e.g. `llmapi`, `cmdline`), use it directly
+- Directory path: `packages/<first-letter>/<package-name>/xmake.lua`
+
+Examples:
+- `llmapi` → `packages/l/llmapi/xmake.lua`
+- `mcpplibs-capi-lua` → `packages/m/mcpplibs-capi-lua/xmake.lua`
+- `cmdline` → `packages/c/cmdline/xmake.lua`
+
+## Step 3: Create Package Definition
+
+Create `packages/<first-letter>/<package-name>/xmake.lua`:
+
+```lua
+package("<package-name>")
+
+    set_homepage("https://github.com/mcpplibs/<repo-name>")
+    set_description("<description>")
+    set_license("<license>")
+
+    add_urls(
+        "https://github.com/mcpplibs/<repo-name>/archive/refs/tags/$(version).tar.gz",
+        "https://github.com/mcpplibs/<repo-name>.git"
+    )
+
+    add_versions("<version>", "<sha256>")
+
+    -- add dependencies if any
+    add_deps("<dep1>")
+
+    on_install(function (package)
+        local configs = {}
+        -- If repo has examples/tests targets, specify library target only
+        -- to avoid parallel C++23 std module compilation conflicts
+        import("package.tools.xmake").install(package, configs, {target = "<target-name>"})
+        -- If cppm files reference headers not installed by default, copy them manually
+        -- os.cp("src/path/to/header.h", package:installdir("include"))
+    end)
+```
+
+### Key Pitfalls
+
+- **Target isolation**: If the upstream repo includes examples/tests via `includes()`, they will be built during package install. This causes parallel `std` module compilation conflicts with GCC. Fix: pass `{target = "<name>"}` as the 3rd argument to `install()`.
+- **Missing headers**: C++20 modules using `#include` in the global module fragment need those headers installed. Check the `.cppm` files for `#include "xxx.h"` and add `os.cp(...)` in `on_install`.
+- **Links**: If consumers need to link against specific libraries, add `on_load` with `package:add("links", "xxx")`.
+
+## Step 4: Create Test
+
+Create `tests/<first-letter>/<package-name>/xmake.lua`:
+
+```lua
+add_requires("<package-name> <version>")
+
+target("<package-name>_test")
+    set_kind("binary")
+    add_languages("c++23")
+    add_files("main.cpp")
+    add_packages("<package-name>")
+    set_policy("build.c++.modules", true)
+```
+
+**Do NOT** add `add_repositories()` here — it's handled by `tests/xmake.lua`.
+
+Create `tests/<first-letter>/<package-name>/main.cpp` with a minimal usage example based on the library's examples or README.
+
+## Step 5: Register Test in Top-Level
+
+Add an `includes()` line to `tests/xmake.lua`:
+
+```lua
+includes("<first-letter>/<package-name>")
+```
+
+## Step 6: Verify Build
+
+```bash
+# Clean any cached package
+rm -rf ~/.xmake/packages/<first-letter>/<package-name>
+
+# Configure and install from tests/ directory
+cd tests/
+xmake f -y -c
+
+# Build the specific test target
+xmake build <package-name>_test
+
+# Run it
+xmake run <package-name>_test
+```
+
+All three commands must succeed before proceeding.
+
+## Step 7: Create Branch, Commit & Push
+
+```bash
+git checkout -b add-<repo-name>-library
+git add packages/<first-letter>/<package-name>/xmake.lua \
+       tests/<first-letter>/<package-name>/xmake.lua \
+       tests/<first-letter>/<package-name>/main.cpp \
+       tests/xmake.lua
+git commit -m "add <package-name> library"
+git push -u upstream add-<repo-name>-library
+```
+
+Use `upstream` (SSH remote) for push, not `origin` (HTTPS, no auth).
+
+## Checklist
+
+- [ ] Package directory name == `package("xxx")` name
+- [ ] SHA256 matches release tarball
+- [ ] `on_install` specifies target if repo has examples/tests
+- [ ] Extra headers copied in `on_install` if needed by cppm
+- [ ] Test does NOT have `add_repositories()` (top-level handles it)
+- [ ] Test registered in `tests/xmake.lua` via `includes()`
+- [ ] `xmake build` succeeds
+- [ ] `xmake run` produces expected output
+- [ ] Committed and pushed to upstream

tests/c/cmdline/xmake.lua

@@ -1,5 +1,3 @@
-add_repositories("mcpplibs-index https://github.com/mcpplibs/mcpplibs-index.git")
-
 add_requires("cmdline", {system = false})
 
 target("cmdline_test")

tests/l/llmapi/capi/xmake.lua

@@ -1,5 +1,3 @@
-add_repositories("mcpplibs-index https://github.com/mcpplibs/mcpplibs-index.git")
-
 add_requires("llmapi 0.0.1", {configs = { capi = true }})
 
 target("llmapi_test_c")

tests/l/llmapi/xmake.lua

@@ -1,5 +1,3 @@
-add_repositories("mcpplibs-index https://github.com/mcpplibs/mcpplibs-index.git")
-
 add_requires("llmapi 0.0.2")
 
 target("llmapi_test")

tests/l/lua/xmake.lua

@@ -1,5 +1,3 @@
-add_repositories("mcpplibs-index https://github.com/mcpplibs/mcpplibs-index.git")
-
 add_requires("mcpplibs-capi-lua 0.0.1")
 
 target("lua_test")

tests/t/templates/xmake.lua

@@ -1,5 +1,3 @@
-add_repositories("mcpplibs-index https://github.com/mcpplibs/mcpplibs-index.git")
-
 add_requires("templates 0.0.1")
 --add_requires("mcpplibs-index::templates 0.0.1") -- TODO: impl prefix support in xmake
 

tests/xmake.lua

@@ -0,0 +1,7 @@
+add_repositories("mcpplibs-index ../")
+
+includes("l/llmapi")
+includes("l/llmapi/capi")
+includes("l/lua")
+includes("c/cmdline")
+includes("t/templates")