diff --git a/default/region/china/cargo.toml b/default/region/china/cargo.toml
new file mode 100644
index 00000000..5b56b114
--- /dev/null
+++ b/default/region/china/cargo.toml
@@ -0,0 +1,5 @@
+[source.crates-io]
+replace-with = "aliyun"
+
+[source.aliyun]
+registry = "sparse+https://mirrors.aliyun.com/crates.io-index/"
diff --git a/default/region/china/environment.conf b/default/region/china/environment.conf
new file mode 100644
index 00000000..2bb3dd16
--- /dev/null
+++ b/default/region/china/environment.conf
@@ -0,0 +1,8 @@
+NPM_CONFIG_REGISTRY=https://registry.npmmirror.com
+PIP_INDEX_URL=https://mirrors.aliyun.com/pypi/simple/
+UV_DEFAULT_INDEX=https://mirrors.aliyun.com/pypi/simple/
+GOPROXY=https://mirrors.aliyun.com/goproxy/,direct
+RUSTUP_DIST_SERVER=https://mirrors.aliyun.com/rustup
+RUSTUP_UPDATE_ROOT=https://mirrors.aliyun.com/rustup/rustup
+BUNDLE_MIRROR__ALL=https://mirrors.aliyun.com/rubygems/
+MAVEN_ARGS=--global-settings /usr/share/omarchy/default/region/china/maven-settings.xml
diff --git a/default/region/china/gemrc b/default/region/china/gemrc
new file mode 100644
index 00000000..145984f2
--- /dev/null
+++ b/default/region/china/gemrc
@@ -0,0 +1,3 @@
+---
+:sources:
+- https://mirrors.aliyun.com/rubygems/
diff --git a/default/region/china/maven-settings.xml b/default/region/china/maven-settings.xml
new file mode 100644
index 00000000..5066b6bd
--- /dev/null
+++ b/default/region/china/maven-settings.xml
@@ -0,0 +1,9 @@
+<settings>
+  <mirrors>
+    <mirror>
+      <id>aliyun</id>
+      <mirrorOf>central</mirrorOf>
+      <url>https://maven.aliyun.com/repository/public</url>
+    </mirror>
+  </mirrors>
+</settings>
diff --git a/install/config/region.sh b/install/config/region.sh
index 4ed4bc62..65bfefec 100644
--- a/install/config/region.sh
+++ b/install/config/region.sh
@@ -1,10 +1,31 @@
+china_links=(
+  "environment.conf /etc/environment.d/90-omarchy-china.conf"
+  "cargo.toml /.cargo/config.toml"
+  "gemrc /etc/gemrc"
+)
+
 case ${OMARCHY_REGION:-global} in
 global)
   rm -f /etc/omarchy/region
+  for link in "${china_links[@]}"; do
+    read -r _ target <<<"$link"
+    if [[ -L $target && $(readlink "$target") == */default/region/china/* ]]; then
+      rm "$target"
+    fi
+  done
   ;;
 china)
   mkdir -p /etc/omarchy
   echo china >/etc/omarchy/region
+  for link in "${china_links[@]}"; do
+    read -r source target <<<"$link"
+    if [[ -e $target && ! -L $target ]]; then
+      echo "Refusing to replace $target, which Omarchy did not create" >&2
+      exit 1
+    fi
+    mkdir -p "${target%/*}"
+    ln -sfn "$OMARCHY_PATH/default/region/china/$source" "$target"
+  done
   omarchy-pkg-add fcitx5-configtool fcitx5-rime librime opencc rime-ice-installer
   ;;
 *)
diff --git a/plans/omarchycn.md b/plans/omarchycn.md
index 11594ca2..c26fc834 100644
--- a/plans/omarchycn.md
+++ b/plans/omarchycn.md
@@ -18,7 +18,7 @@ Progress source of truth for the `omarchycn` branches of `omarchy`, `omarchy-iso
 - [x] T2 Region choice in the installer (PRD 2): `omarchy_prompt_region` in `setup-form.sh`, ISO configurator screen, orchestrator passes `OMARCHY_REGION`, `install/config/region.sh` records it
 - [x] T3 Input method (PRD 3): rime-ice-installer patch and PKGBUILD in omarchy-pkgs, IME packages in `omarchy-other.packages`, install-time package add, user step runs the installer from bundled assets, ISO build bundles assets and the package
 - [x] T4 CJK fontconfig fix (PRD 4): rebuild PR 9693 on the current base
-- [ ] T5 AI (PRD 5): Dim and Kimi Code for every region (rebuild PR 9694), Claude Code third-party provider setup shown only in China
+- [x] T5 AI (PRD 5): Dim and Kimi Code for every region (rebuild PR 9694), Claude Code third-party provider setup shown only in China
 - [ ] T6 Developer mirrors (PRD 6): npm, PyPI/uv, Go, rustup, crates.io, RubyGems, Maven via system drop-ins under `default/region/china/`
 - [ ] T7 China software (PRD 7): Install menu entry shown only in China
 - [ ] T8 Region switching and Chinese UI (PRD 8): `omarchy-region china|global`, Setup > Region, locale, Chinese menu overlay chosen by `LANG`
diff --git a/test/shell.d/region-test.sh b/test/shell.d/region-test.sh
index ed6e58e3..e251ae94 100755
--- a/test/shell.d/region-test.sh
+++ b/test/shell.d/region-test.sh
@@ -66,11 +66,13 @@ chmod +x "$stub_bin"/*
 PATH="$stub_bin:$PATH"
 
 region_setup="$test_tmp/region.sh"
-sed "s|/etc/omarchy|$test_tmp/etc-omarchy|g" "$ROOT/install/config/region.sh" >"$region_setup"
+root="$test_tmp/root"
+sed -e "s|/etc/|$root/etc/|g" -e "s| /\.cargo/| $root/.cargo/|g" "$ROOT/install/config/region.sh" >"$region_setup"
+export OMARCHY_PATH="$ROOT"
 
 : >"$calls"
 OMARCHY_REGION=china bash -e "$region_setup"
-[[ $(<"$test_tmp/etc-omarchy/region") == "china" ]] || fail "install records the China region"
+[[ $(<"$root/etc/omarchy/region") == "china" ]] || fail "install records the China region"
 [[ $(<"$calls") == "omarchy-pkg-add fcitx5-configtool fcitx5-rime librime opencc rime-ice-installer" ]] ||
   fail "China installs the Rime input method packages" "$(<"$calls")"
 for package in fcitx5-configtool fcitx5-rime librime opencc rime-ice-installer; do
@@ -78,13 +80,35 @@ for package in fcitx5-configtool fcitx5-rime librime opencc rime-ice-installer;
 done
 pass "install records the China region and installs the Rime packages the ISO carries"
 
+for link in "environment.conf etc/environment.d/90-omarchy-china.conf" "cargo.toml .cargo/config.toml" "gemrc etc/gemrc"; do
+  read -r source target <<<"$link"
+  [[ $(readlink "$root/$target") == "$ROOT/default/region/china/$source" ]] || fail "China links /$target to the shipped $source"
+done
+pass "China links the developer mirror drop-ins"
+
 : >"$calls"
 OMARCHY_REGION=global bash -e "$region_setup"
-[[ ! -e $test_tmp/etc-omarchy/region ]] || fail "install records Global by leaving no region file"
+[[ ! -e $root/etc/omarchy/region ]] || fail "install records Global by leaving no region file"
 [[ ! -s $calls ]] || fail "Global installs no input method packages" "$(<"$calls")"
+[[ ! -e $root/etc/environment.d/90-omarchy-china.conf && ! -e $root/.cargo/config.toml && ! -e $root/etc/gemrc ]] ||
+  fail "Global removes the developer mirror drop-ins"
+pass "Global removes the developer mirror drop-ins"
+
+ln -s /usr/share/somewhere/gemrc "$root/etc/gemrc"
+OMARCHY_REGION=global bash -e "$region_setup"
+[[ -L $root/etc/gemrc ]] || fail "Global keeps a gemrc link Omarchy did not create"
+rm "$root/etc/gemrc"
+echo ":sources: []" >"$root/etc/gemrc"
+if output=$(OMARCHY_REGION=china bash -e "$region_setup" 2>&1); then
+  fail "China refuses to replace an admin's /etc/gemrc" "$output"
+fi
+[[ $output == "Refusing to replace $root/etc/gemrc, which Omarchy did not create" && $(<"$root/etc/gemrc") == ":sources: []" ]] ||
+  fail "China names the file it refuses to replace and leaves it" "$output"
+rm "$root/etc/gemrc"
+pass "region setup never touches mirror config Omarchy did not create"
 OMARCHY_REGION=china bash -e "$region_setup"
 env -u OMARCHY_REGION bash -e "$region_setup"
-[[ ! -e $test_tmp/etc-omarchy/region ]] || fail "an installer that passes no region installs Global"
+[[ ! -e $root/etc/omarchy/region ]] || fail "an installer that passes no region installs Global"
 pass "Global and an unset region leave no region file"
 
 if output=$(OMARCHY_REGION=mars bash -e "$region_setup" 2>&1); then