diff --git a/README.md b/README.md
index 77d6100..eb678b2 100644
--- a/README.md
+++ b/README.md
@@ -107,6 +107,17 @@ FreeBSD's; before, which identity a system's runner is was a table of the
 engine. The version group is that of 0.26.0. An mcpp earlier than 2026.11.12.1
 names the key it does not read and ignores it.
 
+Platform 0.27.1 is a patch of the group. The implementations retire a handle
+before closing it: openkal-linux 0.26.1, openkal-macos 0.23.1 and
+openkal-windows 0.21.1. A connection, a listener and a datagram socket were
+closed first, so a file another thread opened at that moment was left with a
+stale handle, and above openkal-musl its reads and writes reached descriptor 0
+(openkal-linux#53). openkal-musl 0.29.4 delivers the byte a `poll` held together
+with what else has arrived from `recv`, `recvfrom` and `recvmsg`, as `read`
+does; before, a program that polls before each `recv` took a stream one byte
+per call (openkal-musl#52). The group stays on openkal-windows 0.21, the line
+openkal-run and mcpplibs.os name. The platform's statements are those of 0.27.0.
+
 A project overrides any group under `[target.<selector>]`, for example
 `[target.'cfg(platform = "openkal")'.layers] "c++-abi" = false`, and selects
 another platform, or none, with `platform = "..."` or `--platform`.
diff --git a/mcpp.toml b/mcpp.toml
index 2abfd0a..8cbca29 100644
--- a/mcpp.toml
+++ b/mcpp.toml
@@ -12,7 +12,7 @@
 [package]
 namespace   = "mcpplibs"
 name        = "openkal-platform"
-version     = "0.27.0"
+version     = "0.27.1"
 description = "The platform of ok images (<arch>-openkal): their toolchain, C library and C++ run-time, tools, compile and link conventions, seal, runner and carrier, as one versioned statement mcpp reads."
 license     = "Apache-2.0"
 authors     = ["mcpplibs"]
@@ -53,7 +53,7 @@ debuggee = ["okrun", "--debugger", "{}"]
 [platform.layers]
 compiler-runtime = "openkal-llvm-runtime@0.20.1"
 "c++-abi"        = "openkal-llvm-runtime@0.20.1"
-c-abi            = { name = "openkal-musl", version = "0.29.2", default-features = false, features = ["posix", "malloc-mimalloc"] }
+c-abi            = { name = "openkal-musl", version = "0.29.4", default-features = false, features = ["posix", "malloc-mimalloc"] }
 
 # Built for the building machine: `okld` writes and checks the notes, `okrun`
 # runs an image, `okprof` reads what a measured run recorded (0.23.0: the
@@ -179,7 +179,7 @@ toolchain = "llvm@23.1.3"
 [platform.hosted.layers]
 compiler-runtime = "openkal-llvm-runtime@0.20.1"
 "c++-abi"        = "openkal-llvm-runtime@0.20.1"
-c-abi            = { name = "openkal-musl", version = "0.29.2", default-features = false, features = ["posix", "malloc-mimalloc"] }
+c-abi            = { name = "openkal-musl", version = "0.29.4", default-features = false, features = ["posix", "malloc-mimalloc"] }
 
 # The family released together for openkal 0.17 (the 0.17.2 round: okb, the
 # runner's bundle and library interfaces, musl's renameat2; the 0.17.3 round:
@@ -222,18 +222,21 @@ c-abi            = { name = "openkal-musl", version = "0.29.2", default-features
 # over kal_fs_hard_link), openkal-llvm-runtime 0.20.0 and openkal-image 0.5.5;
 # 0.26.0, openkal-image 0.6.1 (the runner binds the interfaces its
 # implementation provides), openkal-freebsd 0.1.0 beneath openkal-musl 0.29.2 and
-# openkal-llvm-runtime 0.20.1 on FreeBSD): one version of each in a build. From 0.24.1 the members name one another by
+# openkal-llvm-runtime 0.20.1 on FreeBSD; 0.27.1, the implementations retire a
+# handle before closing it (openkal-linux 0.26.1, openkal-macos 0.23.1,
+# openkal-windows 0.21.1) and openkal-musl 0.29.4 delivers what a readiness
+# enquiry held with the rest): one version of each in a build. From 0.24.1 the members name one another by
 # compatible ranges (`^0.28.0`) and this group chooses the versions: mcpp
 # 2026.11.7.1 resolves within it, and a fix of one member is that member's
 # release and a patch of this group, released together through one index change
 # (tools/family_release.py, .github/workflows/family-release.yml).
 [platform.versions]
 openkal              = "0.25.0"
-openkal-linux        = "0.26.0"
-openkal-macos        = "0.23.0"
-openkal-windows      = "0.21.0"
+openkal-linux        = "0.26.1"
+openkal-macos        = "0.23.1"
+openkal-windows      = "0.21.1"
 openkal-freebsd      = "0.1.0"
-openkal-musl         = "0.29.2"
+openkal-musl         = "0.29.4"
 openkal-llvm-runtime = "0.20.1"
 openkal-ld           = "0.6.1"
 openkal-run          = "0.6.1"