diff --git a/.claude/hooks/session-start.sh b/.claude/hooks/session-start.sh
index 35cddfb3b4..c3c873bcca 100755
--- a/.claude/hooks/session-start.sh
+++ b/.claude/hooks/session-start.sh
@@ -174,6 +174,43 @@ if [ -n "${CLAUDE_ENV_FILE:-}" ]; then
   echo "export PATH=\$PATH:$ANDROID_SDK_DIR/platform-tools" >> "$CLAUDE_ENV_FILE"
 fi
 
+# --- Kotlin/Native: pre-install native dependencies (GCC sysroot, LLDB) ---
+# The K/N compiler downloads these on first use, but that fails through the proxy.
+# Pre-download them so K/N benchmarks and linuxX64 compilation work out of the box.
+KONAN_DIR="/root/.konan"
+KONAN_DEPS_URL="https://download.jetbrains.com/kotlin/native"
+KONAN_DEPS_DIR="$KONAN_DIR/dependencies"
+
+install_konan_dep() {
+  local dep_name="$1"
+  local url="$2"  # full download URL
+  # Already extracted?
+  if [ -d "$KONAN_DEPS_DIR/$dep_name" ]; then
+    return 0
+  fi
+  local archive="$dep_name.tar.gz"
+  local cache_dir="$KONAN_DEPS_DIR/cache"
+  mkdir -p "$cache_dir"
+  if [ ! -f "$cache_dir/$archive" ]; then
+    echo "Downloading K/N dependency $dep_name..."
+    curl -fsSL "$url" -o "$cache_dir/$archive" || {
+      echo "Failed to download $dep_name" >&2; return 1
+    }
+  fi
+  echo "Extracting $dep_name..."
+  tar -xzf "$cache_dir/$archive" -C "$KONAN_DEPS_DIR"
+}
+
+# Dependencies for linuxX64 target (from konan.properties for Kotlin 2.3.20)
+install_konan_dep "x86_64-unknown-linux-gnu-gcc-8.3.0-glibc-2.19-kernel-4.9-2" \
+  "$KONAN_DEPS_URL/x86_64-unknown-linux-gnu-gcc-8.3.0-glibc-2.19-kernel-4.9-2.tar.gz"
+install_konan_dep "lldb-4-linux" \
+  "$KONAN_DEPS_URL/lldb-4-linux.tar.gz"
+install_konan_dep "llvm-19-x86_64-linux-essentials-109" \
+  "$KONAN_DEPS_URL/resources/llvm/19-x86_64-linux/llvm-19-x86_64-linux-essentials-109.tar.gz"
+install_konan_dep "libffi-3.2.1-2-linux-x86-64" \
+  "$KONAN_DEPS_URL/libffi-3.2.1-2-linux-x86-64.tar.gz"
+
 cd "$CLAUDE_PROJECT_DIR"
 ./gradlew --version > /dev/null 2>&1
 
diff --git a/quartz/benchmarks/run_all.sh b/quartz/benchmarks/run_all.sh
index 72fa418019..8442f327d0 100755
--- a/quartz/benchmarks/run_all.sh
+++ b/quartz/benchmarks/run_all.sh
@@ -82,26 +82,25 @@ fi
 echo ""
 
 # ============================================================================
-# 2. Kotlin/Native benchmark (Linux and macOS)
+# 2. Kotlin/Native benchmark
 # ============================================================================
-echo "=== Running Kotlin/Native benchmark ==="
-case "$OS_NAME" in
-    Linux)
-        KN_TARGET="linuxX64Test"
-        ;;
-    Darwin)
-        KN_TARGET="macosArm64Test"
-        ;;
-esac
+# macosArm64 target is blocked until negentropy-kmp publishes a macosArm64
+# artifact. Once unblocked, add:  Darwin) KN_TARGET="macosArm64Test" ;;
+if [ "$OS_NAME" = "Linux" ]; then
+    echo "=== Running Kotlin/Native benchmark ==="
+    KN_TARGET="linuxX64Test"
 
-"$ROOT/gradlew" -p "$ROOT" ":quartz:$KN_TARGET" --tests "*.Secp256k1NativeBenchmark" \
-    2>/dev/null || true
+    "$ROOT/gradlew" -p "$ROOT" ":quartz:$KN_TARGET" --tests "*.Secp256k1NativeBenchmark" \
+        2>/dev/null || true
 
-KN_XML="$ROOT/quartz/build/test-results/$KN_TARGET/TEST-${KN_TARGET}.com.vitorpamplona.quartz.utils.secp256k1.Secp256k1NativeBenchmark.xml"
-if [ -f "$KN_XML" ]; then
-    sed -n '/<!\[CDATA\[/,/\]\]>/p' "$KN_XML" | grep -v 'CDATA\|]]>'
+    KN_XML="$ROOT/quartz/build/test-results/$KN_TARGET/TEST-${KN_TARGET}.com.vitorpamplona.quartz.utils.secp256k1.Secp256k1NativeBenchmark.xml"
+    if [ -f "$KN_XML" ]; then
+        sed -n '/<!\[CDATA\[/,/\]\]>/p' "$KN_XML" | grep -v 'CDATA\|]]>'
+    else
+        echo "K/Native benchmark XML not found."
+    fi
 else
-    echo "K/Native benchmark XML not found."
+    echo "=== Skipping Kotlin/Native benchmark (only linuxX64 target available) ==="
 fi
 echo ""
 
diff --git a/quartz/build.gradle.kts b/quartz/build.gradle.kts
index 1a852bca82..5d7d8ac194 100644
--- a/quartz/build.gradle.kts
+++ b/quartz/build.gradle.kts
@@ -87,7 +87,7 @@ kotlin {
 
     linuxX64()
 
-    macosArm64()
+    // macosArm64() — blocked until negentropy-kmp publishes a macosArm64 artifact
 
     // This makes sure that the resource file directory is visible for iOS tests.
     val rootDir = "${rootProject.rootDir.path}/quartz/src/commonTest/resources"
@@ -299,23 +299,8 @@ kotlin {
             dependsOn(iosTest.get())
         }
 
-        val macosMain =
-            create("macosMain") {
-                dependsOn(appleMain)
-            }
-
-        val macosTest =
-            create("macosTest") {
-                dependsOn(appleTest)
-            }
-
-        val macosArm64Main by getting {
-            dependsOn(macosMain)
-        }
-
-        val macosArm64Test by getting {
-            dependsOn(macosTest)
-        }
+        // macosMain/macosTest source sets exist but are not wired until
+        // negentropy-kmp publishes a macosArm64 artifact.
 
         val linuxMain =
             create("linuxMain") {