@@ -671,3 +671,43 @@ lld-required-absent 拒绝没有变化。报告器在 iOS 的五个描述字段
 simulator 输出 sim(payload)。这些列不参与支持判定，记录其输出
 不构成 iOS 链接 glibc 的声明；实际 Apple 依赖以目标验收为准。
 基线注释明确这一边界，没有通过修改报告器扩大本次支持范围。
+
+
+## 29. 2026-10-08 生态 E2E 工具供应统一与非空宿主对照
+
+维护者将后续合入顺序改为检查达标后先报告，由维护者 review 决定。
+索引 #938 已在此前明确授权下合入；mcpp #781 未合入、未发布。
+源码 `3d90198f` 的运行 37765253396 已通过四宿主构建、invariants、
+244 格扫描、三个目标系统执行及 ARM64 fresh-install。剩余生态
+E2E 停留在工具准备步骤超过 24 分钟，维护者确认实际日志为空。
+上一轮同一步骤为 44 秒；两次 33 MB qemu-riscv 下载分别为 2.2 秒
+和 1.4 秒。空输出不能证明具体阻塞在 APT 还是后续命令，不能以此
+声明 LLVM 或 openkal 回归，也不能把尚未执行的 E2E 计为通过。
+
+该步骤原来只通过 xlings 安装 qemu-riscv；qemu-user 和用于宿主
+头文件对照的 mingw-w64 仍来自 APT。现有索引已提供
+qemu-user-aarch64@7.2.0、qemu-riscv@9.2.4-1 及 Linux 宿主的
+mingw-cross-gcc@16.1.0。工具供应改为三个具名 xlings 步骤，不再
+访问 APT。用户态与系统态模拟器分别安装到两个被调用的 home，
+安装作用域和激活版本显式指定；准备后的程序执行仍为准入条件。
+
+索引中的 mingw-w64 是 Windows 载荷，不能用于 Linux 宿主。
+Linux 头文件对照使用独立 XLINGS_HOME 中的 mingw-cross-gcc，
+目录位于 MCPP_HOME 外。738 仅在自身进程内将该工具链 bin 加入
+PATH，不写入 /usr，不导出 GCC_ROOT，不将对照载荷混入被信任的
+图供应 store。Clang 无默认配置时能通过 PATH 找到这份真实头文件；
+正向控制要求实际预处理 io.h 并报告该 include 目录，才继续验证
+图供应命令的搜索目录。CI 除原 PASS 行外还要求正向控制成功行。
+
+本地 LLVM 23.1.3 对照实测：未限制的驱动搜索独立 MinGW include
+并成功预处理 io.h；加 nostdlibinc 后该目录消失，io.h 不可找到。
+原实际图构建/CDB 隔离判据保留，不以模拟数据或成功退出代替。
+本批只改变测试供应与诊断，无引擎、工具链默认值、载荷或运行时
+功能改动。新头仍需实际生态 E2E 和最终 CI 成功，之后才交付合入
+报告。发布、CN/SubOS 消费及 latest 移动继续等待合入决定。
+
+维护者确认运行卡住后，于 11:42 UTC 取消旧运行。最终为 54 成功、
+1 条件跳过、1 取消；准备步骤连续静默约 43 分钟，完整取消日志
+仍没有后续命令的实际输出。归档、已完成检查和实测矩阵保留，
+不将取消解释为功能通过或 LLVM 回归。工作流和覆盖检查的 25 个
+现有专项用例、本批 shell/YAML、版本关系及文档规范检查通过。
@@ -606,40 +606,38 @@ jobs:
       # the shim on PATH dispatches against whichever home owns it, so an
       # emulator installed only in the ambient one answers "not installed" when
       # mcpp asks.
-      - name: Install the emulators, and this host's mingw-w64 (#662)
+      - name: Install the AArch64 user emulator with xlings
         run: |
           set -euo pipefail
-          # The runner image carries third-party apt lists (Google Chrome
-          # among them) that this job does not use, and a transient
-          # `Hash Sum mismatch` on one of them fails the whole update -- which
-          # killed two cross-build jobs in setup, before a single byte was
-          # compiled. Dropping the lists this job has no use for is what makes
-          # the step's failure mean something about this job.
-          #
-          # BY CONTENT, NOT BY FILENAME. The first attempt removed
-          # `google-chrome.list` and the update failed on the same URL: on
-          # ubuntu-24.04 the runner writes deb822 `.sources` files, so the
-          # name was a guess and the guess was wrong.
-          sudo grep -rlE 'dl[.]google[.]com|packages[.]microsoft[.]com' \
-               /etc/apt/sources.list.d/ 2>/dev/null | xargs -r sudo rm -f
-          # `mingw-w64` (the distro package, NOT `mingw-cross-gcc`) is what
-          # 738's `mingw-host-headers` capability probes for
-          # (`/usr/x86_64-w64-mingw32/include`). The assertion it gates --
-          # clang's own driver no longer searches the host once a graph
-          # package supplies the target's C library -- has no discriminating
-          # power without a host copy to have leaked in in the first place;
-          # this is the one runner in the fleet that installs it for that
-          # reason (run_all.sh's capability probe, and the design doc's note
-          # on `# requires:` gates CI never satisfies on its own).
-          sudo apt-get update -qq && sudo apt-get install -y -qq qemu-user mingw-w64
-          "$XLINGS_BIN" install xim:qemu-riscv -y
+          "$XLINGS_BIN" install xim:qemu-user-aarch64@7.2.0 -g -y -u
+          XLINGS_HOME="${MCPP_HOME:-$HOME/.mcpp}/registry" \
+            "$XLINGS_BIN" install xim:qemu-user-aarch64@7.2.0 -g -y -u
+          qemu-aarch64-static --version
+
+      - name: Install the RISC-V system emulator with xlings
+        run: |
+          set -euo pipefail
+          "$XLINGS_BIN" install xim:qemu-riscv@9.2.4-1 -g -y -u
           XLINGS_HOME="${MCPP_HOME:-$HOME/.mcpp}/registry" \
-            "$XLINGS_BIN" install xim:qemu-riscv -y
-          # Reachable AND runnable, asserted before the tests: without this the
-          # scripts would simply skip and say so in a line nobody reads.
-          qemu-aarch64 --version | head -1
-          "$XLINGS_BIN" run qemu-system-riscv64 --version 2>/dev/null | head -1 \
-            || command -v qemu-system-riscv64
+            "$XLINGS_BIN" install xim:qemu-riscv@9.2.4-1 -g -y -u
+          "$XLINGS_BIN" run qemu-system-riscv64 --version
+
+      - name: Install the separate host MinGW header fixture with xlings
+        run: |
+          set -euo pipefail
+          source tests/e2e/_toolchain_env.sh
+          # This store stays outside MCPP_HOME. Test 738 first proves that
+          # unrestricted Clang finds its headers through PATH, then proves
+          # that the graph-supplied C library closes that host search.
+          export XLINGS_HOME="$RUNNER_TEMP/openkal-host-mingw"
+          mkdir -p "$XLINGS_HOME"
+          cd "$XLINGS_HOME"
+          "$XLINGS_BIN" config --mirror GLOBAL
+          "$XLINGS_BIN" install "xim:mingw-cross-gcc@$MINGW_CROSS_VERSION" -g -y
+          host_root="$XLINGS_HOME/data/xpkgs/xim-x-mingw-cross-gcc/$MINGW_CROSS_VERSION"
+          test -f "$host_root/x86_64-w64-mingw32/include/io.h"
+          test -x "$host_root/bin/x86_64-w64-mingw32-gcc"
+          echo "MCPP_E2E_HOST_MINGW_ROOT=$host_root" >> "$GITHUB_ENV"
 
       - name: The scripts
         run: |
@@ -707,6 +705,8 @@ jobs:
             "OK: the list answers what can be built, not what has a payload" || fail=1
           check 738_a_graph_supplied_target_closes_the_hosts_own_search.sh \
             "PASS: 738 a graph-supplied target closes the host's own search" || fail=1
+          check 738_a_graph_supplied_target_closes_the_hosts_own_search.sh \
+            "ok: unprotected clang finds the separate host MinGW headers" || fail=1
           # mcpp#696, the link-side twin of 738: both legs, because the one
           # that separates the engines is the refusal, and a skip of either
           # prints the final line all the same.
 
@@ -32,21 +32,49 @@ source "$(dirname "${BASH_SOURCE[0]}")/_toolchain_env.sh"
 # that never had it -- the search list would end at the compiler's own
 # resource directory before AND after this fix, for an unrelated reason.
 #
-# `# requires: llvm` is why this test does not run through the ordinary
-# sharded suite at all -- `llvm` is never in run_all.sh's detected CAPS on
-# any shard (nothing there installs a toolchain), so every script declaring
-# it is invoked DIRECTLY, with the capability installed first and its PASS
-# line demanded, the same way openkal-cross.yml's `ecosystem-e2e` job
-# already runs 285-294: it installs the distro `mingw-w64` package there
-# specifically so `mingw-host-headers` holds and this test is not a
-# guaranteed skip.
+# The dedicated CI job supplies an xlings-managed MinGW fixture in a
+# separate store. An unrestricted driver must first find those headers;
+# only then can their absence from graph-supplied commands prove isolation.
+# Ordinary suites can still use the distro's host MinGW prefix.
 set -e
 
 MCPP="${MCPP:-mcpp}"
 TMP=$(mktemp -d)
 trap 'rm -rf "$TMP"' EXIT
 fail() { echo "FAIL: $1"; [ -n "${2:-}" ] && cat "$2"; exit 1; }
 
+# PATH exposes a genuine host cross toolchain, outside the store whose
+# include paths the graph is allowed to use. Do not export GCC_ROOT: it is
+# a compiler control variable, not a fixture label.
+if [ -n "${MCPP_E2E_HOST_MINGW_ROOT:-}" ]; then
+    export PATH="$MCPP_E2E_HOST_MINGW_ROOT/bin:$PATH"
+    python3 - "$LLVM_ROOT/bin/clang" "$MCPP_E2E_HOST_MINGW_ROOT" "${MCPP_HOME:-$HOME/.mcpp}" <<'PYCONTROL'
+from pathlib import Path
+import subprocess, sys
+compiler, root, home = sys.argv[1], Path(sys.argv[2]).resolve(), Path(sys.argv[3]).resolve()
+if root.is_relative_to(home):
+    sys.exit("FAIL: the host MinGW fixture must be outside MCPP_HOME")
+include = (root / "x86_64-w64-mingw32/include").resolve()
+if not (include / "io.h").is_file():
+    sys.exit("FAIL: the separate host MinGW headers are absent")
+r = subprocess.run([compiler, "--no-default-config", "--target=x86_64-w64-windows-gnu",
+                    "-E", "-v", "-x", "c", "-"], input="#include <io.h>\n",
+                   capture_output=True, text=True)
+searched, capture = [], False
+for line in r.stderr.splitlines():
+    if "search starts here" in line:
+        capture = True
+    elif "End of search list" in line:
+        capture = False
+    elif capture:
+        searched.append(Path(line.strip()).resolve())
+if r.returncode != 0 or include not in searched:
+    print(r.stderr)
+    sys.exit("FAIL: unrestricted Clang did not find the host MinGW fixture")
+print("ok: unprotected clang finds the separate host MinGW headers")
+PYCONTROL
+fi
+
 mkdir -p "$TMP/app/src"
 cd "$TMP/app"
 
 
@@ -93,16 +93,13 @@ case "$OS" in
         if ls "${MCPP_HOME}"/registry/data/xpkgs/xim-x-llvm/*/bin/clang++ 2>/dev/null | head -1 | grep -q .; then
             CAPS+=(llvm)
         fi
-        # mingw-host-headers: this Linux HOST's own mingw-w64 headers
-        # (`apt install mingw-w64`, distro package). Distinct from both
-        # `mingw-cross` above (an xim-managed cross GCC) and `mingw` below (a
-        # Windows-hosted payload) — this is a plain probe for
-        # `/usr/x86_64-w64-mingw32/include`, the exact directory #662's
-        # isolation criterion has to prove clang no longer searches once a
-        # graph package supplies the target's C library. The criterion has NO
-        # discriminating power without it: a host that never had these headers
-        # would pass the same assertion before the fix and after it.
-        [[ -d /usr/x86_64-w64-mingw32/include ]] && CAPS+=(mingw-host-headers)
+        # Host MinGW headers can come from a distro prefix or the dedicated
+        # xlings fixture outside MCPP_HOME. Test 738 proves that unrestricted
+        # Clang finds the latter before checking graph isolation.
+        if [[ -d /usr/x86_64-w64-mingw32/include ]] \
+           || [[ -n "${MCPP_E2E_HOST_MINGW_ROOT:-}" && -f "$MCPP_E2E_HOST_MINGW_ROOT/x86_64-w64-mingw32/include/io.h" ]]; then
+            CAPS+=(mingw-host-headers)
+        fi
         # wine: run cross-built Windows PE artifacts on the Linux host.
         command -v wine &>/dev/null && CAPS+=(wine)
         # qemu-riscv: the emulator a bare-metal riscv artifact runs in