diff --git a/.github/scripts/prepare_mlx_darwin.sh b/.github/scripts/prepare_mlx_darwin.sh
index 6b2d083f19..f08011da80 100755
--- a/.github/scripts/prepare_mlx_darwin.sh
+++ b/.github/scripts/prepare_mlx_darwin.sh
@@ -1,15 +1,21 @@
 #!/usr/bin/env bash
 
-# Prepare prebuilt MLX Metal runtime libraries for macOS CI unit tests.
+# Prepare MLX runtime libraries for macOS CI unit tests.
 #
 # Building MLX is expensive, so to enable the MLX-specific unit tests this
 # helper finds the newest Ollama release whose MLX_VERSION and MLX_C_VERSION
 # match the current checkout, downloads that release's ollama-darwin.tgz, and
-# extracts only mlx_metal_v* into build/lib/ollama
+# extracts only mlx_metal_v* into build/lib/ollama.
 #
-# If no matching release artifact exists, the helper only emits a warning. That
-# covers the expected window after an MLX update lands and before the next release
-# publishes a matching Darwin payload.
+# The payload also depends on Ollama's payload build rules (cmake glue and
+# carried mlx/compat patches) and the xgrammar native wrapper
+# (x/mlxrunner/xgrammar/native). Rule drift rebuilds the whole payload from
+# source; wrapper-only drift rebuilds just libollama_xgrammar.dylib.
+#
+# If no release matches the MLX pins (e.g. right after a pin bump), the
+# helper builds the minimal MLX payload for this platform: a single Metal
+# variant using the superbuild's platform default (metal_v4 on macOS 26.2+
+# SDKs, otherwise metal_v3), including a fresh libollama_xgrammar.dylib.
 
 set -euo pipefail
 
@@ -17,6 +23,7 @@ repo="${OLLAMA_MLX_RELEASE_REPO:-ollama/ollama}"
 scan_limit="${OLLAMA_MLX_RELEASE_SCAN_LIMIT:-50}"
 cache_dir="${OLLAMA_MLX_DARWIN_CACHE:-.cache/mlx-darwin-release}"
 target_dir="${OLLAMA_MLX_DARWIN_TARGET:-build/lib/ollama}"
+ci_build_dir="${OLLAMA_MLX_CI_BUILD_DIR:-build/mlx-ci}"
 tarball="${cache_dir}/ollama-darwin.tgz"
 tag_file="${cache_dir}/matched-tag"
 pins_file="${cache_dir}/matched-pins"
@@ -42,6 +49,71 @@ read_pin() {
   tr -d '[:space:]' <"$1"
 }
 
+# Native wrapper sources compiled into libollama_xgrammar.dylib — keep in
+# sync with the ollama_xgrammar target in cmake/mlx/CMakeLists.txt.
+xgrammar_native_dir=x/mlxrunner/xgrammar/native
+
+# Payload build rules beyond the MLX_VERSION/MLX_C_VERSION pins.
+payload_rule_files=(
+  "cmake/local.cmake"
+  "cmake/apply-git-patches.cmake"
+  "cmake/mlx/CMakeLists.txt"
+  "cmake/mlx/CMakePresets.json"
+  "x/mlxrunner/mlx/CMakeLists.txt"
+)
+
+# Build-rule inputs: the rule files plus carried MLX/MLX-C patch content.
+rule_inputs() {
+  local file
+  for file in "${payload_rule_files[@]}"; do
+    printf '%s\n' "${file}"
+  done
+  if [ -d mlx/compat ]; then
+    find mlx/compat -type f | sort
+  fi
+}
+
+wrapper_inputs() {
+  find "${xgrammar_native_dir}" -type f | sort
+}
+
+payload_inputs() {
+  rule_inputs
+  wrapper_inputs
+}
+
+payload_fingerprint() {
+  local file
+  {
+    payload_inputs
+    while IFS= read -r file; do
+      cat "${file}" 2>/dev/null || true
+    done < <(payload_inputs)
+  } | shasum -a 256 | awk '{print $1}'
+}
+
+# True when the tag matches the checkout on all payload inputs.
+tag_matches_payload() {
+  local tag="$1" file
+  while IFS= read -r file; do
+    if ! curl -fsSL "https://raw.githubusercontent.com/${repo}/${tag}/${file}" 2>/dev/null | cmp -s - "${file}"; then
+      return 1
+    fi
+  done < <(payload_inputs)
+  return 0
+}
+
+# True when the tag matches the checkout on the build rules.
+tag_matches_rules() {
+  local tag="$1" file
+  while IFS= read -r file; do
+    if ! curl -fsSL "https://raw.githubusercontent.com/${repo}/${tag}/${file}" 2>/dev/null | cmp -s - "${file}"; then
+      return 1
+    fi
+  done < <(rule_inputs)
+  return 0
+}
+
 has_payload() {
   local variant
   for variant in "${target_dir}"/mlx_metal_v*; do
@@ -54,7 +126,14 @@ has_payload() {
 has_matching_payload() {
   [ -f "${target_pins_file}" ] || return 1
   [ "$(cat "${target_pins_file}")" = "${current_pins}" ] || return 1
-  has_payload
+  has_payload || return 1
+  # Every payload variant must carry libollama_xgrammar.dylib.
+  local variant
+  for variant in "${target_dir}"/mlx_metal_v*; do
+    [ -d "${variant}" ] || continue
+    [ -f "${variant}/libollama_xgrammar.dylib" ] || return 1
+  done
+  return 0
 }
 
 extract_payload() {
@@ -89,6 +168,85 @@ extract_payload() {
   tmpdir=""
 }
 
+# Resolve the superbuild's platform-default MLX backend (metal_v3/metal_v4 on
+# arm64; empty when the platform has no MLX backend, e.g. x86_64 macOS).
+ci_mlx_backend() {
+  [ -f "${ci_build_dir}/CMakeCache.txt" ] || return 1
+  sed -n 's/^OLLAMA_MLX_BACKENDS:STRING=//p' "${ci_build_dir}/CMakeCache.txt"
+}
+
+# Configure the repo-root superbuild and fetch MLX/MLX-C sources at the
+# pinned revisions (only the full payload build needs this).
+build_ci_sources() {
+  cmake -S . -B "${ci_build_dir}" \
+    -DOLLAMA_LLAMA_BACKENDS= \
+    -DOLLAMA_PAYLOAD_INSTALL_PREFIX="$(dirname "$(dirname "${target_dir}")")"
+  cmake --build "${ci_build_dir}" --target ollama-mlx-sources --parallel
+}
+
+# Rebuild only libollama_xgrammar.dylib into the extracted payload. The
+# target depends only on the pinned XGrammar sources and the native wrapper;
+# the Metal toolchain and the superbuild are not involved. MLX is fetched
+# only because the cmake/mlx project defines it — nothing from it is built.
+build_ci_xgrammar() {
+  local lib variant
+  local xg_build_dir="${ci_build_dir}/xgrammar"
+  local -a configure_args=(-S cmake/mlx -B "${xg_build_dir}" -DOLLAMA_SOURCE_DIR="$(pwd)" -DMLX_BUILD_METAL=OFF)
+  if [ -n "${OLLAMA_XGRAMMAR_SOURCE:-}" ]; then
+    configure_args+=("-DFETCHCONTENT_SOURCE_DIR_XGRAMMAR=${OLLAMA_XGRAMMAR_SOURCE}")
+  fi
+  cmake "${configure_args[@]}"
+  cmake --build "${xg_build_dir}" --target ollama_xgrammar --parallel
+  lib="${xg_build_dir}/lib/ollama/libollama_xgrammar.dylib"
+  [ -f "${lib}" ] || {
+    echo "ollama_xgrammar build produced no library at ${lib}" >&2
+    exit 1
+  }
+  for variant in "${target_dir}"/mlx_metal_v*; do
+    [ -d "${variant}" ] || continue
+    cp -f "${lib}" "${variant}/libollama_xgrammar.dylib"
+    [ -f "${variant}/libollama_xgrammar.dylib" ] || {
+      echo "failed to install ${variant}/libollama_xgrammar.dylib" >&2
+      exit 1
+    }
+  done
+  echo "Rebuilt libollama_xgrammar.dylib from source into ${target_dir}"
+}
+
+# Build the minimal MLX payload for this platform: one Metal variant,
+# whatever the superbuild defaults to here.
+build_ci_payload() {
+  local backend variant
+  build_ci_sources
+  backend="$(ci_mlx_backend)"
+  case "${backend}" in
+    metal_v3 | metal_v4) ;;
+    *)
+      warn "no MLX backend applicable to this platform; MLX unit tests will be skipped"
+      exit 0
+      ;;
+  esac
+  echo "Building the ${backend} payload for unit tests"
+  rm -rf "${target_dir}"/mlx_metal_v*
+  cmake --build "${ci_build_dir}" --target "ollama-mlx-${backend}" --parallel
+  for variant in "${target_dir}"/mlx_metal_v*; do
+    [ -d "${variant}" ] || continue
+    for lib in libmlx.dylib libmlxc.dylib libollama_xgrammar.dylib; do
+      [ -f "${variant}/${lib}" ] || {
+        echo "built payload is missing ${variant}/${lib}" >&2
+        exit 1
+      }
+    done
+  done
+  has_payload || {
+    echo "built payload is incomplete in ${target_dir}" >&2
+    exit 1
+  }
+  echo "${current_pins}" >"${target_pins_file}"
+  echo "Built MLX payload for unit tests:"
+  find "${target_dir}" -maxdepth 2 -type f \( -name 'libmlx.dylib' -o -name 'libmlxc.dylib' -o -name 'libollama_xgrammar.dylib' -o -name '*.metallib' \) -print
+}
+
 if [ "$(uname -s)" != "Darwin" ]; then
   warn "MLX Darwin payload setup is only supported on macOS"
   exit 0
@@ -96,64 +254,87 @@ fi
 
 current_mlx="$(read_pin MLX_VERSION)"
 current_mlxc="$(read_pin MLX_C_VERSION)"
-current_pins="${current_mlx} ${current_mlxc}"
+# The release tarball only depends on the MLX pins; the extracted payload's
+# xgrammar library additionally depends on the tree's XGrammar inputs.
+component_pins="${current_mlx} ${current_mlxc}"
+current_pins="${component_pins} $(payload_fingerprint)"
 
 if has_matching_payload; then
-  echo "MLX Darwin payload already present in ${target_dir}"
+  echo "MLX payload already present in ${target_dir}"
   exit 0
 fi
 
 mkdir -p "${cache_dir}"
 
-if [ -s "${tarball}" ] && [ -f "${tag_file}" ] && [ "$(cat "${pins_file}" 2>/dev/null || true)" = "${current_pins}" ]; then
+if [ -s "${tarball}" ] && [ -f "${tag_file}" ] && [ "$(cat "${pins_file}" 2>/dev/null || true)" = "${component_pins}" ]; then
   extract_payload "$(cat "${tag_file}")"
+else
+  matched_tag=""
+  matched_url=""
+
+  while read -r tag; do
+    [ -n "${tag}" ] || continue
+
+    if ! tag_mlx="$(curl -fsSL "https://raw.githubusercontent.com/${repo}/${tag}/MLX_VERSION" | tr -d '[:space:]')"; then
+      continue
+    fi
+    if [ "${tag_mlx}" != "${current_mlx}" ]; then
+      continue
+    fi
+
+    if ! tag_mlxc="$(curl -fsSL "https://raw.githubusercontent.com/${repo}/${tag}/MLX_C_VERSION" | tr -d '[:space:]')"; then
+      continue
+    fi
+    if [ "${tag_mlxc}" != "${current_mlxc}" ]; then
+      continue
+    fi
+
+    url="https://github.com/${repo}/releases/download/${tag}/ollama-darwin.tgz"
+    if curl -fsIL "${url}" >/dev/null; then
+      matched_tag="${tag}"
+      matched_url="${url}"
+      break
+    fi
+
+    echo "MLX pins match ${tag}, but ${url} is not available"
+  done < <(
+    git ls-remote --tags --refs --sort=-version:refname "https://github.com/${repo}.git" 'v*' |
+      awk -v limit="${scan_limit}" '{ sub("refs/tags/", "", $2); print $2; if (limit > 0 && NR >= limit) exit }'
+  )
+
+  if [ -z "${matched_tag}" ]; then
+    echo "No release carries MLX_VERSION=${current_mlx} MLX_C_VERSION=${current_mlxc}"
+    build_ci_payload
+    exit 0
+  fi
+
+  tmp_tarball="${tarball}.tmp"
+  rm -f "${tmp_tarball}"
+  curl -fL --retry 3 --retry-delay 2 -o "${tmp_tarball}" "${matched_url}"
+  mv "${tmp_tarball}" "${tarball}"
+  tmp_tarball=""
+  echo "${matched_tag}" >"${tag_file}"
+  echo "${component_pins}" >"${pins_file}"
+
+  extract_payload "${matched_tag}"
+fi
+
+if tag_matches_payload "$(cat "${tag_file}")"; then
   exit 0
 fi
 
-matched_tag=""
-matched_url=""
-
-while read -r tag; do
-  [ -n "${tag}" ] || continue
-
-  if ! tag_mlx="$(curl -fsSL "https://raw.githubusercontent.com/${repo}/${tag}/MLX_VERSION" | tr -d '[:space:]')"; then
-    continue
-  fi
-  if [ "${tag_mlx}" != "${current_mlx}" ]; then
-    continue
-  fi
-
-  if ! tag_mlxc="$(curl -fsSL "https://raw.githubusercontent.com/${repo}/${tag}/MLX_C_VERSION" | tr -d '[:space:]')"; then
-    continue
-  fi
-  if [ "${tag_mlxc}" != "${current_mlxc}" ]; then
-    continue
-  fi
-
-  url="https://github.com/${repo}/releases/download/${tag}/ollama-darwin.tgz"
-  if curl -fsIL "${url}" >/dev/null; then
-    matched_tag="${tag}"
-    matched_url="${url}"
-    break
-  fi
-
-  echo "MLX pins match ${tag}, but ${url} is not available"
-done < <(
-  git ls-remote --tags --refs --sort=-version:refname "https://github.com/${repo}.git" 'v*' |
-    awk -v limit="${scan_limit}" '{ sub("refs/tags/", "", $2); print $2; if (limit > 0 && NR >= limit) exit }'
-)
-
-if [ -z "${matched_tag}" ]; then
-  warn "MLX unit tests are temporarily disabled until a release build publishes ollama-darwin.tgz for MLX_VERSION=${current_mlx} MLX_C_VERSION=${current_mlxc}"
+if [ "$(uname -m)" != "arm64" ]; then
+  warn "MLX payload builds are only supported on arm64 macOS; MLX unit tests will be skipped"
   exit 0
 fi
 
-tmp_tarball="${tarball}.tmp"
-rm -f "${tmp_tarball}"
-curl -fL --retry 3 --retry-delay 2 -o "${tmp_tarball}" "${matched_url}"
-mv "${tmp_tarball}" "${tarball}"
-tmp_tarball=""
-echo "${matched_tag}" >"${tag_file}"
-echo "${current_pins}" >"${pins_file}"
+if tag_matches_rules "$(cat "${tag_file}")"; then
+  # Only the xgrammar wrapper drifted; keep the rest of the release payload.
+  echo "Rebuilding libollama_xgrammar.dylib from source into ${target_dir}"
+  rm -f "${target_dir}"/mlx_metal_v*/libollama_xgrammar.dylib
+  build_ci_xgrammar
+  exit 0
+fi
 
-extract_payload "${matched_tag}"
+echo "Release payload build rules do not match this checkout"
+build_ci_payload
\ No newline at end of file