Raise min_mcpp and both CI MCPP_VERSION pins to 2026.9.18.2

2026.9.18.2 is the release whose refusals match [c-abi]: an empty
realisation is accepted under GCC, and presents = "posix" is realised on
macOS and on freestanding targets instead of refused. The two packages
that declare the block pin this release in their own CI; the floor must
not leave them refused at 2026.9.18.1.

Author: Sunrisepeak

.github/workflows/openkal-compat.yml

@@ -33,7 +33,7 @@ env:
   # run if this drifts from pins.toml. See the comment beside `mcpp` in
   # pins.toml for why this pin, not just validate.yml's, is gated by the
   # index floor.
-  MCPP_VERSION: "2026.9.18.1"
+  MCPP_VERSION: "2026.9.18.2"
   XLINGS_NON_INTERACTIVE: "1"
 
 jobs:

.github/workflows/validate.yml

@@ -301,7 +301,7 @@ env:
   # is a cold one (mcpp's build-cache epoch moved from 2 to 3 in this same
   # release, because the old cache key did not cover the realised [c-abi]
   # environment).
-  MCPP_VERSION: "2026.9.18.1"
+  MCPP_VERSION: "2026.9.18.2"
 
 jobs:
   lint:

index.toml

@@ -54,6 +54,20 @@
 # for byte, as before. Verified here, not merely asserted: every descriptor
 # in pkgs/*/*.lua still parses with `mcpp xpkg parse` under 2026.9.18.1.
 #
+# ── 2026-09-18: raised 2026.9.18.1 -> 2026.9.18.2, with both CI pins ────────
+#
+# 2026.9.18.2 is the release whose refusals match the feature it ships: a
+# [c-abi] declaration whose realisation needs no tokens (Linux) is accepted
+# under GCC instead of refused, `presents = "posix"` is realised on macOS
+# (one token, -D__unix__; Apple's clang never predefines it) and on a
+# freestanding target (the same token) instead of refused. openkal-musl
+# 0.15.0 and openkal-llvm-runtime 0.11.0 pin this release in their own CI;
+# a floor at 2026.9.18.1 would let a 2026.9.18.1 user be refused builds the
+# next release accepts. Per the rule at the top of this file, this moves in
+# the same commit as validate.yml's `MCPP_VERSION`; openkal-compat.yml's
+# `MCPP_VERSION` moves with tests/openkal/pins.toml's `mcpp`, which that
+# workflow checks for agreement.
+#
 # openkal-musl 0.15.0 and openkal-llvm-runtime 0.11.0 (plan step 3) -- the two
 # packages that will actually declare and consume `[c-abi] presents =
 # "posix"` -- are NOT registered by this raise. Neither has a version number
@@ -67,5 +81,5 @@
 # does not need.
 [index]
 spec        = "1"
-min_mcpp    = "2026.9.18.1"
-latest_mcpp = "2026.9.18.1"
+min_mcpp    = "2026.9.18.2"
+latest_mcpp = "2026.9.18.2"

tests/openkal/pins.toml

@@ -27,7 +27,7 @@ toolchain = "llvm@22.1.8"
 # the checked-in baseline exactly -- same 27 runs / 3 fails, same three
 # members (expat, curl, cmp-module), same diagnostics character-for-character
 # past the local path prefix.
-mcpp      = "2026.9.18.1"
+mcpp      = "2026.9.18.2"
 
 targets = ["x86_64-linux-gnu", "x86_64-windows-gnu"]