diff --git a/.gitignore b/.gitignore
index 5073bb55..c76a2b5e 100644
--- a/.gitignore
+++ b/.gitignore
@@ -127,6 +127,12 @@ backend/app/services/libqemu-*.dll.pre-camera
 backend/app/services/libqemu-*.dll.new
 backend/app/services/libqemu-*.dll.bak
 
+# Obsolete Windows-only QEMU build helpers (MSYS2/MINGW64). Superseded by
+# docs/BUILD-QEMU.md (Linux/macOS .so via lcgamboa/qemu) and the prebuilt /
+# CDN binary flow; kept local-only on the operator's box, never tracked.
+/build_qemu_all.sh
+/build_qemu_step4.sh
+
 # esp32-camera repo is cloned during dev (used as include path by the
 # arduino-esp32 toolchain via ARDUINO_ESP32_PATH). Not a submodule and
 # not part of the main repo — gitignored to keep the working tree clean.
diff --git a/build_qemu_all.sh b/build_qemu_all.sh
deleted file mode 100644
index 869cc788..00000000
--- a/build_qemu_all.sh
+++ /dev/null
@@ -1,72 +0,0 @@
-#!/usr/bin/env bash
-# Build both libqemu-xtensa.dll and libqemu-riscv32.dll with slirp (WiFi)
-# and copy them to backend/app/services/.
-#
-# Run from MSYS2 MINGW64 shell:
-#   cd /e/Hardware/wokwi_clon
-#   bash build_qemu_all.sh
-
-set -euo pipefail
-
-REPO_ROOT="$(cd "$(dirname "$0")" && pwd)"
-QEMU_DIR="${REPO_ROOT}/third-party/qemu-lcgamboa"
-BACKEND_SERVICES="${REPO_ROOT}/backend/app/services"
-
-echo "=== Building QEMU ESP32 DLLs (Xtensa + RISC-V) with slirp ==="
-echo "  QEMU source: ${QEMU_DIR}"
-echo "  Output dir:  ${BACKEND_SERVICES}"
-echo ""
-
-cd "${QEMU_DIR}"
-
-# Step 1: Build both targets
-echo "--- Running build script ---"
-bash build_libqemu-esp32-win.sh
-
-# Step 2: Copy DLLs to backend
-echo ""
-echo "=== Copying DLLs to backend ==="
-
-if [ -f build/libqemu-xtensa.dll ]; then
-    cp build/libqemu-xtensa.dll "${BACKEND_SERVICES}/"
-    echo "  Copied libqemu-xtensa.dll ($(du -h build/libqemu-xtensa.dll | cut -f1))"
-else
-    echo "  WARNING: libqemu-xtensa.dll not found!"
-fi
-
-if [ -f build/libqemu-riscv32.dll ]; then
-    cp build/libqemu-riscv32.dll "${BACKEND_SERVICES}/"
-    echo "  Copied libqemu-riscv32.dll ($(du -h build/libqemu-riscv32.dll | cut -f1))"
-else
-    echo "  WARNING: libqemu-riscv32.dll not found!"
-fi
-
-# Step 3: Verify slirp in both DLLs
-echo ""
-echo "=== Verifying slirp support ==="
-
-for dll in libqemu-xtensa.dll libqemu-riscv32.dll; do
-    path="${BACKEND_SERVICES}/${dll}"
-    if [ -f "$path" ]; then
-        if objdump -p "$path" 2>/dev/null | grep -q "libslirp"; then
-            echo "  ${dll}: slirp OK"
-        else
-            echo "  ${dll}: WARNING - slirp NOT found!"
-        fi
-    fi
-done
-
-# Step 4: Verify picsimlab exports
-echo ""
-echo "=== Verifying picsimlab exports ==="
-
-for dll in libqemu-xtensa.dll libqemu-riscv32.dll; do
-    path="${BACKEND_SERVICES}/${dll}"
-    if [ -f "$path" ]; then
-        count=$(objdump -p "$path" 2>/dev/null | grep -c "picsimlab" || true)
-        echo "  ${dll}: ${count} picsimlab exports"
-    fi
-done
-
-echo ""
-echo "=== Done ==="
diff --git a/build_qemu_step4.sh b/build_qemu_step4.sh
deleted file mode 100644
index 33634828..00000000
--- a/build_qemu_step4.sh
+++ /dev/null
@@ -1,109 +0,0 @@
-#!/usr/bin/env bash
-# Step 4: Relink qemu-system-xtensa as libqemu-xtensa.dll
-set -euo pipefail
-export PATH=/mingw64/bin:/usr/bin:$PATH
-
-BUILD="/e/Hardware/wokwi_clon/third-party/qemu-lcgamboa/build"
-OUT="/e/Hardware/wokwi_clon/backend/app/services"
-cd "$BUILD"
-
-echo "=== Extracting link command from build.ninja ==="
-
-python3 << 'PYEOF'
-import re, subprocess, sys, os
-
-with open('build.ninja') as f:
-    content = f.read()
-
-# Find build block for qemu-system-xtensa.exe
-idx = content.find('build qemu-system-xtensa.exe:')
-if idx < 0:
-    print('Target not found!'); sys.exit(1)
-
-block = content[idx:]
-end = block.find('\nbuild ', 1)
-if end > 0:
-    block = block[:end]
-
-# Extract LINK_ARGS and LINK_PATH
-link_args = ''
-link_path = ''
-for line in block.split('\n'):
-    line = line.strip()
-    if line.startswith('LINK_ARGS ='):
-        link_args = line.split('=', 1)[1].strip()
-    elif line.startswith('LINK_PATH ='):
-        link_path = line.split('=', 1)[1].strip()
-
-# Extract all input objects (everything after c_LINKER_RSP on line 1, excluding the | deps part)
-first_line = block.split('\n')[0]
-# Remove "build qemu-system-xtensa.exe: c_LINKER_RSP "
-objs_raw = first_line.split('c_LINKER_RSP ', 1)[1]
-# Remove pipe section (| implicit deps)
-if ' | ' in objs_raw:
-    objs_raw = objs_raw.split(' | ')[0]
-objs = objs_raw.split()
-
-# Remove softmmu_main.c.obj (contains main())
-objs = [o for o in objs if 'softmmu_main' not in o]
-
-# Also add qemu-system-xtensa.exe.p objects (target-specific .obj files)
-# Find them in the .p directory
-p_dir = 'qemu-system-xtensa.exe.p'
-if os.path.isdir(p_dir):
-    for f in os.listdir(p_dir):
-        if f.endswith('.obj') and 'softmmu_main' not in f:
-            path = f'{p_dir}/{f}'
-            if path not in objs:
-                objs.append(path)
-
-print(f'Objects count: {len(objs)}')
-print(f'LINK_ARGS: {link_args[:200]}')
-print(f'LINK_PATH: {link_path}')
-
-# Build the DLL link command
-cmd = (
-    f'cc -m64 -mcx16 -shared -Wl,--export-all-symbols -Wl,--allow-multiple-definition '
-    f'-o libqemu-xtensa.dll '
-    f'{" ".join(objs)} '
-    f'{link_path} '
-    f'{link_args}'
-)
-
-print(f'\nLink command length: {len(cmd)}')
-
-# Write to a response file to avoid command line length issues
-with open('dll_link.rsp', 'w') as f:
-    f.write(
-        f'-shared -Wl,--export-all-symbols -Wl,--allow-multiple-definition '
-        f'-o libqemu-xtensa.dll '
-        f'{" ".join(objs)} '
-        f'{link_path} '
-        f'{link_args}'
-    )
-
-print('Written to dll_link.rsp')
-PYEOF
-
-echo ""
-echo "=== Linking libqemu-xtensa.dll ==="
-cc -m64 -mcx16 @dll_link.rsp 2>&1
-echo "=== Link exit code: $? ==="
-
-if [ -f libqemu-xtensa.dll ]; then
-    echo ""
-    echo "=== SUCCESS: libqemu-xtensa.dll ==="
-    ls -lh libqemu-xtensa.dll
-
-    echo ""
-    echo "=== Checking picsimlab exports ==="
-    objdump -p libqemu-xtensa.dll 2>/dev/null | grep -iE "picsimlab|qemu_init|qemu_main" | head -20
-
-    echo ""
-    echo "=== Copying to backend/app/services ==="
-    cp libqemu-xtensa.dll "$OUT/"
-    echo "Copied!"
-else
-    echo "FAILED - DLL not produced"
-    exit 1
-fi