feat(index): mcpp:plugins 0.2.1, and a CI pin that follows the engine

`mcpp:plugins` 0.2.1 makes `mcpp.rules.sycl` name the C library. The device
compiler is a second compiler: it does not inherit the toolchain the engine
configured, so without `-isystem` pointing at `xim:glibc` and
`xim:linux-headers` it reads the host's `/usr/include`. The rule now requires
both declarations, unpinned, because the C library version is the runtime
binding's choice and differs between a developer machine and a runner.

The CI pin moves 2026.8.27.2 -> 2026.9.6.2. It had drifted about ten releases
behind, so this index was validated against an engine no user runs.
`llamacpp@b10069.1` made the drift visible rather than causing it: its build
program calls `mcpp::toolchain_sysroot()` and `mcpp::toolchain_binutils_dir()`
for the same reason as above, and under the old pin the workspace members could
not compile it. The members build `b10069.1` again.

`index.toml` min_mcpp does not move. It states the oldest mcpp able to RESOLVE
every descriptor, and all 218 parse under both versions; raising it would refuse
the whole index to a client on the floor over a build-program API that client
may never reach. `b10069` stays published for exactly that case.

Author: Sunrisepeak

.github/workflows/validate.yml

@@ -163,7 +163,28 @@ env:
   #   - mcpp#405 依赖 BMI 缓存命中时,被恢复的包传递依赖的 `std` 没进构建图 ——
   #     **每个图形项目的第二次构建必挂**(消费方自己不 `import std` 时现形)。
   #   - mcpp#407 `mcpp build` 会重放 `mcpp test` 留下的构建图。
-  MCPP_VERSION: "2026.8.27.2"
+  #
+  # 2026-09-06: raised 2026.8.27.2 -> 2026.9.6.2.
+  #
+  # The pin had drifted about ten releases behind, so this index was validated
+  # against an engine no user runs. `llamacpp@b10069.1` made the drift visible
+  # rather than causing it: its build program calls `mcpp::toolchain_sysroot()`
+  # and `mcpp::toolchain_binutils_dir()` (mcpp 2026.9.5.2+) to hand the
+  # ecosystem C library to the second compiler it drives, and under the old pin
+  # the workspace members failed to compile it. A package whose build program
+  # uses a current engine API is not a defect; a CI that cannot run current
+  # engines is.
+  #
+  # `index.toml` min_mcpp deliberately does NOT move with this. The floor states
+  # the oldest mcpp able to RESOLVE every descriptor -- descriptor grammar --
+  # and every one of the 218 descriptors here parses under both versions. A
+  # client on 2026.8.27.2 keeps the whole index; only `llamacpp@b10069.1`, whose
+  # build program needs the newer accessors, is out of reach for it, and
+  # `b10069` remains published for exactly that case. Raising the floor instead
+  # would refuse the index to that client entirely, which is the failure mode
+  # `index-floor-must-degrade` names: the index is data, mcpp is the program,
+  # and publishing data must not invalidate the program.
+  MCPP_VERSION: "2026.9.6.2"
 
 jobs:
   lint:

pkgs/g/ggml-org.llamacpp.lua

@@ -24,26 +24,27 @@ package = {
 
     xpm = {
         linux = {
-            -- b10069.1 ADDS `backend-vulkan`, AND ITS BUILD PROGRAM NEEDS A NEWER
-            -- mcpp THAN THIS INDEX'S CI PINS. It calls `mcpp::toolchain_sysroot()`
-            -- and `mcpp::toolchain_binutils_dir()` (mcpp 2026.9.5.2+) to tell the
-            -- shader generator's compiler where the ecosystem's C library is;
-            -- without them it reads the host's, which is the dependency this
-            -- ecosystem removes. On an older mcpp the build program does not
-            -- compile, and the error names the function rather than the version --
-            -- a qualified name that does not exist is ill-formed, not `false`, so
-            -- no package can probe for it (mcpp docs/07).
+            -- b10069.1 ADDS `backend-vulkan`, AND ITS BUILD PROGRAM NEEDS mcpp
+            -- 2026.9.5.2+. It calls `mcpp::toolchain_sysroot()` and
+            -- `mcpp::toolchain_binutils_dir()` to tell the shader generator's
+            -- compiler where the ecosystem's C library is; without them that
+            -- compiler reads the host's, which is the dependency this ecosystem
+            -- removes. On an older mcpp the build program does not compile, and
+            -- the error names the function rather than the version -- a qualified
+            -- name that does not exist is ill-formed, not `false`, so no package
+            -- can probe for it (mcpp docs/07).
             --
-            -- The workspace members therefore stay on `b10069`: this index's CI
-            -- pins 2026.8.27.2, and what it can build is what builds for users of
-            -- that version. The new version's build is verified where it belongs,
-            -- in llama.cpp-m's own CI, which pins 2026.9.6.2 and runs the backend
-            -- on a software Vulkan device with no GPU.
+            -- This entry is what raised the CI pin to 2026.9.6.2 (validate.yml).
+            -- The pin had drifted about ten releases behind, so it was not this
+            -- package that outran the index; the index had stopped following the
+            -- engine. The workspace members build `b10069.1` under the new pin.
             --
-            -- `min_mcpp` is NOT the lever for this. It states the oldest mcpp that
-            -- can RESOLVE every descriptor, and this descriptor uses no new
-            -- grammar; raising it would brick clients over a build-program API
-            -- they may never reach.
+            -- `min_mcpp` is NOT the lever for this, and does not move. It states
+            -- the oldest mcpp that can RESOLVE every descriptor, and this
+            -- descriptor uses no new grammar. A client on the floor keeps the
+            -- whole index and keeps `b10069`, which stays published for exactly
+            -- that case; raising the floor would refuse the index outright over a
+            -- build-program API such a client may never reach.
             ["b10069.1"] = {
                 url = {
                     GLOBAL = "https://github.com/mcpplibs/llama.cpp-m/archive/refs/tags/b10069.1.tar.gz",

pkgs/m/mcpp.plugins.lua

@@ -2,13 +2,13 @@
 -- each member selected by a feature.
 --
 --   [dependencies.mcpp]
---   plugins = { version = "0.2.0", features = ["rules-spirv"], host-module = true }
+--   plugins = { version = "0.2.1", features = ["rules-spirv"], host-module = true }
 --
 --   // build.mcpp
 --   import mcpp;
 --   import mcpp.rules.spirv;
 --
--- Members of 0.2.0, with the mcpp release each relies on:
+-- Members of 0.2.1, with the mcpp release each relies on:
 --
 --   mcpp.rules.cuda   `rules-cuda`   >= 2026.9.5.2
 --   mcpp.rules.spirv  `rules-spirv`  >= 2026.9.5.3; since 0.2.0 it drives glslc
@@ -26,7 +26,18 @@
 --   mcpp.rules.sycl   `rules-sycl`   >= 2026.9.6.1, the release whose
 --                                    device-source table carries `.sycl`. Needs
 --                                    `compat:sycl-runtime` so the artifact can
---                                    reach `libsycl.so.9` at run time
+--                                    reach `libsycl.so.9` at run time. Since
+--                                    0.2.1 it also names the C library: the
+--                                    device compiler is a second compiler and
+--                                    does not inherit the toolchain the engine
+--                                    configured, so without `-isystem` pointing
+--                                    at `xim:glibc` and `xim:linux-headers` it
+--                                    reads the host's `/usr/include`. The rule
+--                                    requires both declarations and refuses
+--                                    naming them when they are absent; both are
+--                                    unpinned, because the C library version is
+--                                    the runtime binding's choice and differs
+--                                    between a developer machine and a runner
 --
 -- The floor recorded for this package is the HIGHEST of those, so it is the
 -- collection's floor rather than any one feature's: a project on 2026.9.5.4
@@ -56,6 +67,13 @@ package = {
 
     xpm = {
         linux = {
+            ["0.2.1"] = {
+                url = {
+                    GLOBAL = "https://github.com/mcpp-community/mcpp-plugins/archive/refs/tags/v0.2.1.tar.gz",
+                    CN     = "https://gitcode.com/mcpp-res/mcpp-plugins/releases/download/0.2.1/mcpp-plugins-0.2.1.tar.gz",
+                },
+                sha256 = "86dcc5975f7fb17910182bc890536fa2685ef2ca947a405969bd9c74e49a48fe",
+            },
             ["0.2.0"] = {
                 url = {
                     GLOBAL = "https://github.com/mcpp-community/mcpp-plugins/archive/refs/tags/v0.2.0.tar.gz",
@@ -77,9 +95,16 @@ package = {
                 },
                 sha256 = "adf1f9d6691a5d05a8a4a94e83c733ea39caee1510ce2c9af4cb23bebabea9f5",
             },
-            ["latest"] = { ref = "0.2.0" },
+            ["latest"] = { ref = "0.2.1" },
         },
         macosx = {
+            ["0.2.1"] = {
+                url = {
+                    GLOBAL = "https://github.com/mcpp-community/mcpp-plugins/archive/refs/tags/v0.2.1.tar.gz",
+                    CN     = "https://gitcode.com/mcpp-res/mcpp-plugins/releases/download/0.2.1/mcpp-plugins-0.2.1.tar.gz",
+                },
+                sha256 = "86dcc5975f7fb17910182bc890536fa2685ef2ca947a405969bd9c74e49a48fe",
+            },
             ["0.2.0"] = {
                 url = {
                     GLOBAL = "https://github.com/mcpp-community/mcpp-plugins/archive/refs/tags/v0.2.0.tar.gz",
@@ -101,9 +126,16 @@ package = {
                 },
                 sha256 = "adf1f9d6691a5d05a8a4a94e83c733ea39caee1510ce2c9af4cb23bebabea9f5",
             },
-            ["latest"] = { ref = "0.2.0" },
+            ["latest"] = { ref = "0.2.1" },
         },
         windows = {
+            ["0.2.1"] = {
+                url = {
+                    GLOBAL = "https://github.com/mcpp-community/mcpp-plugins/archive/refs/tags/v0.2.1.tar.gz",
+                    CN     = "https://gitcode.com/mcpp-res/mcpp-plugins/releases/download/0.2.1/mcpp-plugins-0.2.1.tar.gz",
+                },
+                sha256 = "86dcc5975f7fb17910182bc890536fa2685ef2ca947a405969bd9c74e49a48fe",
+            },
             ["0.2.0"] = {
                 url = {
                     GLOBAL = "https://github.com/mcpp-community/mcpp-plugins/archive/refs/tags/v0.2.0.tar.gz",
@@ -125,7 +157,7 @@ package = {
                 },
                 sha256 = "adf1f9d6691a5d05a8a4a94e83c733ea39caee1510ce2c9af4cb23bebabea9f5",
             },
-            ["latest"] = { ref = "0.2.0" },
+            ["latest"] = { ref = "0.2.1" },
         },
     },