diff --git a/build.md b/build.md
new file mode 100644
index 0000000..4b358e9
--- /dev/null
+++ b/build.md
@@ -0,0 +1,220 @@
+# KiCad WASM Build System
+
+This document describes how to build KiCad for WebAssembly using the Docker-based build system.
+
+## Prerequisites
+
+- Docker Desktop with ARM64 support (for Apple Silicon) or x86_64
+- 10+ GB disk space for build cache
+- Recommended: 10 CPUs, 16GB RAM allocated to Docker
+
+## Quick Start
+
+```bash
+# Build KiCad WASM (with debug symbols by default, sequential compilation)
+./docker/build.sh
+
+# Build with parallel compilation (faster, requires more RAM)
+./docker/build.sh -j 4
+
+# Build optimized release (smaller WASM, no debug symbols)
+./docker/build.sh --release
+
+# Interactive shell for debugging
+./docker/shell.sh
+```
+
+**Note:** Builds run sequentially by default (`-j 1`) to avoid memory exhaustion in Docker. Use `-j N` for parallel compilation if you have sufficient RAM (at least 16GB for `-j 4`).
+
+**Build outputs:**
+- `build-wasm/kicad-pcbnew/pcbnew/pcbnew.js` - Main WASM loader
+- `build-wasm/kicad-pcbnew/pcbnew/pcbnew.wasm` - WASM binary
+- `build-wasm/kicad-pcbnew/pcbnew/pcbnew.wasm.map` - Source map (debug builds)
+
+## Docker Architecture
+
+**Base image:** `emscripten/emsdk:4.0.2-arm64`
+
+**Volumes:**
+- Source code bind mount: Project root → `/workspace`
+- Build cache (named volume): `kicad-build-cache` → `/workspace/build-wasm`
+- Output bind mount: `./output` → `/workspace/output`
+
+**Entry scripts:**
+| Script | Purpose |
+|--------|---------|
+| `docker/build.sh` | Run build from host |
+| `docker/shell.sh` | Interactive shell in container |
+| `docker/entrypoint.sh` | Sources Emscripten environment |
+
+## Dependencies
+
+| Dependency | Version | Build System | Purpose |
+|-----------|---------|--------------|---------|
+| GLM | 0.9.9.8 | Header-only | Math library |
+| Zstd | 1.5.5 | CMake | Compression for project files |
+| Protobuf | 3.21.12 | CMake | IPC serialization |
+| FreeType | 2.13.2 | CMake | Font rendering |
+| HarfBuzz | 8.3.0 | CMake | Text shaping |
+| Pixman | 0.42.2 | Meson | Pixel manipulation |
+| Cairo | 1.18.0 | Meson | 2D graphics rendering |
+| Boost | 1.84.0 | B2 | Locale library |
+| wxWidgets | 3.3.1 | Autoconf | GUI framework |
+| OpenCASCADE | 7.8.0 | CMake | 3D geometry (optional) |
+| ngspice | 45.2 | Autoconf | SPICE simulation (optional) |
+
+### Build Order
+
+1. **Header-only:** GLM
+2. **Compression/serialization:** Zstd, Protobuf
+3. **Font stack:** FreeType → HarfBuzz
+4. **Graphics:** Pixman → Cairo
+5. **Optional:** OpenCASCADE, ngspice
+6. **GUI framework:** wxWidgets
+7. **Application:** KiCad PCBnew
+
+## Build Flags
+
+| Flag | Description |
+|------|-------------|
+| `--clean` | Full clean rebuild (all deps + wxWidgets + KiCad) |
+| `--no-clean` | Incremental build (don't clean anything) |
+| `--skip-deps` | Skip dependency rebuild |
+| `--release` | Disable debug symbols, enable optimizations |
+| `--debug` | Enable debug symbols (default) |
+| `-j N` | Parallel jobs (default: 1 for sequential builds) |
+
+### Clean Modes
+
+| Mode | Command | What gets cleaned |
+|------|---------|-------------------|
+| **Full clean** | `./docker/build.sh --clean` | All stamps, deps, wxWidgets, sysroot, KiCad |
+| **Default** | `./docker/build.sh` | KiCad build only (reuses deps) |
+| **Incremental** | `./docker/build.sh --no-clean` | Nothing (fastest for iteration) |
+
+**Full clean removes:**
+- `build-wasm/stamps/*` - All build stamps
+- `build-wasm/deps/*` - All dependency builds
+- `build-wasm/wxwidgets-universal` - wxWidgets build
+- `build-wasm/sysroot/*` - Installed headers/libraries
+- `build-wasm/kicad-pcbnew` - KiCad build
+
+### Debug vs Release
+
+**Debug (default):**
+- Compiler: `-g -O0` (DWARF symbols, no optimization)
+- Linker: `-gsource-map` (JavaScript source maps)
+- Output: `~30-50MB` WASM with `.wasm.map` file
+- Use for: Development, debugging WASM exceptions
+
+**Release:**
+- Compiler: `-O2` (optimized)
+- Output: `~15MB` WASM
+- Use for: Production deployment
+
+## Stamp-based Caching
+
+Build progress is tracked with stamp files in `build-wasm/stamps/`:
+
+```
+build-wasm/stamps/
+├── zstd.stamp
+├── protobuf.stamp
+├── freetype.stamp
+├── harfbuzz.stamp
+├── pixman.stamp
+├── cairo.stamp
+├── wxwidgets.stamp
+└── kicad-pcbnew.stamp
+```
+
+**Clear specific component:** `rm build-wasm/stamps/zstd.stamp`
+**Clear all stamps:** `rm -f build-wasm/stamps/*.stamp`
+
+After changing build flags (debug/release), clear stamps to force rebuild.
+
+## Build Scripts
+
+| Script | Purpose |
+|--------|---------|
+| `scripts/build-kicad-wasm.sh` | Master build orchestrator |
+| `scripts/kicad/build-pcbnew.sh` | KiCad PCBnew build |
+| `scripts/build-wxuniversal-wasm.sh` | wxWidgets GUI build |
+| `scripts/deps/build-all-deps.sh` | All dependencies |
+| `scripts/deps/build-*.sh` | Individual dependency builds |
+| `scripts/common/env.sh` | Environment setup |
+| `scripts/common/functions.sh` | Shared utilities |
+| `scripts/common/versions.sh` | Dependency versions |
+
+## Build Times
+
+| Component | Approximate Time |
+|-----------|-----------------|
+| Dependencies (all) | 20-60 minutes |
+| wxWidgets | 10-20 minutes |
+| KiCad PCBnew | 5-15 minutes |
+| **Total fresh build** | **1-2 hours** |
+
+OpenCASCADE is the longest dependency to build (~30 minutes).
+
+## Troubleshooting
+
+### Container freezes during build
+- Check Docker resource allocation (increase CPU/memory)
+- Reduce parallel jobs: `./docker/build.sh -j 4`
+- OpenCASCADE is resource-intensive; consider skipping with separate builds
+
+### Build fails with missing dependency
+- Clear the specific stamp: `rm build-wasm/stamps/<dep>.stamp`
+- Re-run build
+
+### Incremental build not picking up changes
+- Clear KiCad stamp: `rm build-wasm/stamps/kicad-pcbnew.stamp`
+- Use `--no-clean` flag to avoid full rebuild
+
+### WASM exception with numeric error (e.g., `3788888`)
+- Build with debug symbols (default): No `--release` flag
+- Check for `.wasm.map` file
+- Use Chrome DevTools to debug with source maps
+
+### Clear build cache completely
+```bash
+docker volume rm docker_kicad-build-cache
+```
+
+## WASM Compatibility Layer
+
+The WASM port requires compatibility layers for browser execution:
+
+| Directory | Purpose |
+|-----------|---------|
+| `wasm/kiplatform/` | Platform abstraction (app, UI, printing, etc.) |
+| `wasm/libcontext/` | Coroutine/fiber implementation for Asyncify |
+| `wasm/stubs/` | Stub implementations (libgit2, curl) |
+| `wasm/config/` | Build configuration headers |
+| `cmake/` | CMake find modules for dependencies |
+
+## Emscripten Flags
+
+Key flags used in the build:
+
+```
+-pthread -sUSE_PTHREADS=1          # Threading support
+-sASYNCIFY=1                       # Async coroutine support
+-sALLOW_MEMORY_GROWTH=1            # Dynamic memory
+-sINITIAL_MEMORY=256MB             # Starting memory
+-sMAXIMUM_MEMORY=4GB               # Maximum memory
+-sLEGACY_GL_EMULATION              # OpenGL compatibility
+-sMAX_WEBGL_VERSION=2              # WebGL 2.0
+```
+
+## Testing
+
+After building, run the test suite:
+
+```bash
+cd tests
+npm install
+npm run setup:kicad    # Copy WASM from build
+npm run test:kicad     # Run Playwright tests
+```
diff --git a/docker/docker-compose.yml b/docker/docker-compose.yml
index 8d68d41..6e4f34b 100644
--- a/docker/docker-compose.yml
+++ b/docker/docker-compose.yml
@@ -5,12 +5,12 @@ services:
       dockerfile: docker/Dockerfile
     container_name: kicad-wasm-builder
 
-    # Resource limits (M4 Max: 10 cores, 16GB)
+    # Resource limits (adjust based on your machine)
     deploy:
       resources:
         limits:
           cpus: '10'
-          memory: 16G
+          memory: 32G
 
     volumes:
       # Source code (read-write for git operations)
diff --git a/scripts/build-kicad-wasm.sh b/scripts/build-kicad-wasm.sh
index c2b3354..9fc1546 100755
--- a/scripts/build-kicad-wasm.sh
+++ b/scripts/build-kicad-wasm.sh
@@ -9,7 +9,8 @@
 #   --with-occ      Enable OpenCASCADE (3D/STEP support)
 #   --with-ngspice  Enable ngspice (simulation)
 #   --with-pthread  Enable pthreads (multi-threading)
-#   --debug         Debug build with symbols
+#   --release       Release build (optimized, no debug symbols)
+#   --debug         Debug build with symbols (default)
 #   -j N            Parallel jobs (default: nproc)
 #   --help          Show this help
 
@@ -66,6 +67,10 @@ while [[ $# -gt 0 ]]; do
             DEBUG_BUILD=1
             shift
             ;;
+        --release)
+            DEBUG_BUILD=0
+            shift
+            ;;
         -j)
             PARALLEL_JOBS="$2"
             shift 2
@@ -83,7 +88,7 @@ done
 
 # Set defaults if not set
 CLEAN_BUILD=${CLEAN_BUILD:-0}
-DEBUG_BUILD=${DEBUG_BUILD:-0}
+DEBUG_BUILD=${DEBUG_BUILD:-1}  # Debug mode by default (use --release for optimized builds)
 PARALLEL_JOBS=${PARALLEL_JOBS:-$(get_nproc)}
 
 # Export for sub-scripts
diff --git a/scripts/build-wxuniversal-wasm.sh b/scripts/build-wxuniversal-wasm.sh
index 9a5013d..8e702ec 100755
--- a/scripts/build-wxuniversal-wasm.sh
+++ b/scripts/build-wxuniversal-wasm.sh
@@ -22,6 +22,9 @@ PROJECT_ROOT="$(dirname "$SCRIPT_DIR")"
 BUILD_DIR="$PROJECT_ROOT/build-wasm/wxwidgets-universal"
 WX_SOURCE="$PROJECT_ROOT/wxwidgets"
 
+# Use JOBS from env.sh if set, otherwise default to 1 for sequential builds
+JOBS="${JOBS:-1}"
+
 echo "=== Building wxWidgets wxUniversal for WASM ==="
 echo "Project root: $PROJECT_ROOT"
 echo "Build dir: $BUILD_DIR"
@@ -68,8 +71,20 @@ echo "=== Configuring ==="
 # Z_HAVE_UNISTD_H ensures zlib includes <unistd.h> for read/write/lseek
 # Include pcre2 headers from the build directory (generated during configure)
 PCRE2_INCLUDE="$BUILD_DIR/3rdparty/pcre/src"
-export CFLAGS="-DZ_HAVE_UNISTD_H=1"
-export CXXFLAGS="-DZ_HAVE_UNISTD_H=1 -I$PCRE2_INCLUDE"
+
+# Configure debug/release flags based on DEBUG_BUILD environment variable
+if [ "${DEBUG_BUILD:-1}" = "1" ]; then
+    WX_DEBUG_FLAGS="-g -O0"
+    WX_CONFIGURE_DEBUG="--enable-debug"
+    echo "Building wxWidgets in DEBUG mode"
+else
+    WX_DEBUG_FLAGS="-O2"
+    WX_CONFIGURE_DEBUG=""
+    echo "Building wxWidgets in RELEASE mode"
+fi
+
+export CFLAGS="-DZ_HAVE_UNISTD_H=1 ${WX_DEBUG_FLAGS}"
+export CXXFLAGS="-DZ_HAVE_UNISTD_H=1 -I$PCRE2_INCLUDE ${WX_DEBUG_FLAGS}"
 
 emconfigure "$WX_SOURCE/configure" \
     --host=emscripten \
@@ -82,7 +97,8 @@ emconfigure "$WX_SOURCE/configure" \
     --without-libtiff \
     --disable-xlocale \
     --with-cxx=17 \
-    --enable-utf8
+    --enable-utf8 \
+    ${WX_CONFIGURE_DEBUG}
 
 # Build PCRE first to avoid race condition with parallel builds
 # PCRE headers (pcre2.h) must be generated before regex.cpp compiles
@@ -92,8 +108,8 @@ emmake make -C 3rdparty/pcre
 
 # Build wxWidgets
 echo ""
-echo "=== Building wxWidgets ==="
-emmake make -j$(nproc 2>/dev/null || sysctl -n hw.ncpu)
+echo "=== Building wxWidgets (using ${JOBS} parallel jobs) ==="
+emmake make -j${JOBS}
 
 # Create library symlinks (remove -emscripten suffix for CMake compatibility)
 echo ""
diff --git a/scripts/common/env.sh b/scripts/common/env.sh
index 82fa03c..3f28737 100755
--- a/scripts/common/env.sh
+++ b/scripts/common/env.sh
@@ -34,6 +34,32 @@ export EMSDK_QUIET=1
 export EMCC_CFLAGS="-fPIC -DEMSCRIPTEN"
 export EMCC_CXXFLAGS="-fPIC -DEMSCRIPTEN -std=c++17"
 
+# Debug mode (default: ON, use --release to disable)
+# This can be overridden by setting DEBUG_BUILD=0 before sourcing this file
+DEBUG_BUILD="${DEBUG_BUILD:-1}"
+
+if [ "$DEBUG_BUILD" = "1" ]; then
+    export BUILD_TYPE="Debug"
+    export DEBUG_CFLAGS="-g -O0"
+    export DEBUG_LDFLAGS="-g -gsource-map"
+else
+    export BUILD_TYPE="Release"
+    export DEBUG_CFLAGS="-O2"
+    export DEBUG_LDFLAGS=""
+fi
+
+export DEBUG_BUILD BUILD_TYPE DEBUG_CFLAGS DEBUG_LDFLAGS
+
+# Parallel jobs (default to 1 for memory-constrained environments like Docker)
+# Can be overridden with -j N flag or by setting JOBS/PARALLEL_JOBS env vars
+if [ -n "$PARALLEL_JOBS" ]; then
+    export JOBS="$PARALLEL_JOBS"
+elif [ -z "$JOBS" ]; then
+    # Default to 1 for sequential builds (safer for memory)
+    # Use -j N to override for faster builds on machines with more RAM
+    export JOBS=1
+fi
+
 # Common linker flags for WASM
 export WASM_LDFLAGS="\
 -sALLOW_MEMORY_GROWTH=1 \
diff --git a/scripts/common/functions.sh b/scripts/common/functions.sh
index ed66799..36e8b76 100755
--- a/scripts/common/functions.sh
+++ b/scripts/common/functions.sh
@@ -226,7 +226,7 @@ get_nproc() {
 # Parse common command line arguments
 parse_common_args() {
     CLEAN_BUILD=0
-    DEBUG_BUILD=0
+    DEBUG_BUILD="${DEBUG_BUILD:-1}"  # Default ON (use --release to disable)
     PARALLEL_JOBS=$(get_nproc)
 
     while [[ $# -gt 0 ]]; do
@@ -239,6 +239,10 @@ parse_common_args() {
                 DEBUG_BUILD=1
                 shift
                 ;;
+            --release)
+                DEBUG_BUILD=0
+                shift
+                ;;
             -j)
                 PARALLEL_JOBS="$2"
                 shift 2
diff --git a/scripts/deps/build-boost.sh b/scripts/deps/build-boost.sh
index d40d54f..95e1e65 100755
--- a/scripts/deps/build-boost.sh
+++ b/scripts/deps/build-boost.sh
@@ -63,29 +63,38 @@ if [ ! -f "b2" ]; then
     ./bootstrap.sh --with-toolset=gcc
 fi
 
+# Determine boost variant based on DEBUG_BUILD
+if [ "${DEBUG_BUILD:-1}" = "1" ]; then
+    BOOST_VARIANT="debug"
+    BOOST_DEBUG_FLAGS="-g -O0"
+else
+    BOOST_VARIANT="release"
+    BOOST_DEBUG_FLAGS="-O2"
+fi
+
 # Create user-config.jam for Emscripten
-cat > user-config.jam << 'EOF'
+cat > user-config.jam << EOF
 using clang : emscripten
     : em++
-    : <cxxflags>"-pthread"
+    : <cxxflags>"${BOOST_DEBUG_FLAGS} -pthread"
       <linkflags>"-pthread"
     ;
 EOF
 
 # Build only the locale library (and its dependencies)
 # Most of Boost is header-only, we just need locale built
-log_info "Building Boost.Locale..."
-JOBS=${JOBS:-$(sysctl -n hw.ncpu 2>/dev/null || nproc 2>/dev/null || echo 4)}
+log_info "Building Boost.Locale (${BOOST_VARIANT})..."
+# JOBS is set in env.sh (default: 1 for sequential builds, use -j N to override)
 ./b2 -j${JOBS} \
     --user-config=user-config.jam \
     --prefix="${SYSROOT}" \
     --with-locale \
     toolset=clang-emscripten \
-    variant=release \
+    variant=${BOOST_VARIANT} \
     link=static \
     threading=multi \
     runtime-link=static \
-    cxxflags="-pthread" \
+    cxxflags="${BOOST_DEBUG_FLAGS} -pthread" \
     install
 
 create_stamp "${BOOST_STAMP}"
diff --git a/scripts/deps/build-cairo.sh b/scripts/deps/build-cairo.sh
index 15f52ea..e0721c3 100755
--- a/scripts/deps/build-cairo.sh
+++ b/scripts/deps/build-cairo.sh
@@ -56,6 +56,15 @@ log_info "Building Cairo ${CAIRO_VERSION} for WASM..."
 mkdir -p "${CAIRO_BUILD}"
 cd "${CAIRO_BUILD}"
 
+# Determine meson build type based on DEBUG_BUILD
+if [ "${DEBUG_BUILD:-1}" = "1" ]; then
+    MESON_BUILD_TYPE="debug"
+    MESON_DEBUG_FLAGS="'-g', '-O0'"
+else
+    MESON_BUILD_TYPE="release"
+    MESON_DEBUG_FLAGS="'-O2'"
+fi
+
 # Cairo uses meson
 cat > cross-file.txt << EOF
 [binaries]
@@ -81,7 +90,7 @@ pkg_config_libdir = '${SYSROOT}/lib/pkgconfig'
 default_library = 'static'
 b_staticpic = false
 b_pie = false
-c_args = ['-pthread', '-I${SYSROOT}/include', '-I${SYSROOT}/include/freetype2', '-I${SYSROOT}/include/pixman-1']
+c_args = [${MESON_DEBUG_FLAGS}, '-pthread', '-I${SYSROOT}/include', '-I${SYSROOT}/include/freetype2', '-I${SYSROOT}/include/pixman-1']
 c_link_args = ['-pthread', '-L${SYSROOT}/lib']
 pkg_config_path = '${SYSROOT}/lib/pkgconfig'
 EOF
@@ -95,6 +104,7 @@ meson setup "${CAIRO_DIR}" \
     --cross-file cross-file.txt \
     --prefix="${SYSROOT}" \
     --default-library=static \
+    --buildtype=${MESON_BUILD_TYPE} \
     -Dfontconfig=disabled \
     -Dfreetype=enabled \
     -Dglib=disabled \
@@ -108,7 +118,7 @@ meson setup "${CAIRO_DIR}" \
     -Dfreetype2:default_library=static \
     -Dlibpng:default_library=static
 
-JOBS=${JOBS:-$(sysctl -n hw.ncpu 2>/dev/null || nproc 2>/dev/null || echo 4)}
+# JOBS is set in env.sh (default: 1 for sequential builds, use -j N to override)
 ninja -j${JOBS}
 ninja install
 
diff --git a/scripts/deps/build-freetype.sh b/scripts/deps/build-freetype.sh
index 7c68fa4..6a433bc 100755
--- a/scripts/deps/build-freetype.sh
+++ b/scripts/deps/build-freetype.sh
@@ -53,9 +53,11 @@ mkdir -p "${FREETYPE_BUILD}"
 cd "${FREETYPE_BUILD}"
 
 emcmake cmake "${FREETYPE_DIR}" \
-    -DCMAKE_BUILD_TYPE=Release \
+    -DCMAKE_BUILD_TYPE=${BUILD_TYPE:-Debug} \
     -DCMAKE_INSTALL_PREFIX="${SYSROOT}" \
     -DCMAKE_POLICY_VERSION_MINIMUM=3.5 \
+    -DCMAKE_C_FLAGS="${DEBUG_CFLAGS:--g -O0}" \
+    -DCMAKE_CXX_FLAGS="${DEBUG_CFLAGS:--g -O0}" \
     -DFT_DISABLE_BZIP2=ON \
     -DFT_DISABLE_BROTLI=ON \
     -DFT_DISABLE_HARFBUZZ=ON \
diff --git a/scripts/deps/build-harfbuzz.sh b/scripts/deps/build-harfbuzz.sh
index fe26ff1..165116d 100755
--- a/scripts/deps/build-harfbuzz.sh
+++ b/scripts/deps/build-harfbuzz.sh
@@ -57,9 +57,11 @@ cd "${HARFBUZZ_BUILD}"
 
 # HarfBuzz uses meson, but also has CMake support
 emcmake cmake "${HARFBUZZ_DIR}" \
-    -DCMAKE_BUILD_TYPE=Release \
+    -DCMAKE_BUILD_TYPE=${BUILD_TYPE:-Debug} \
     -DCMAKE_INSTALL_PREFIX="${SYSROOT}" \
     -DCMAKE_POLICY_VERSION_MINIMUM=3.5 \
+    -DCMAKE_C_FLAGS="${DEBUG_CFLAGS:--g -O0}" \
+    -DCMAKE_CXX_FLAGS="${DEBUG_CFLAGS:--g -O0}" \
     -DHB_HAVE_FREETYPE=ON \
     -DHB_HAVE_GLIB=OFF \
     -DHB_HAVE_ICU=OFF \
diff --git a/scripts/deps/build-ngspice.sh b/scripts/deps/build-ngspice.sh
index 2a5e5dc..051811a 100755
--- a/scripts/deps/build-ngspice.sh
+++ b/scripts/deps/build-ngspice.sh
@@ -53,9 +53,16 @@ mkdir -p "${NGSPICE_BUILD}"
 cd "${NGSPICE_BUILD}"
 
 # ngspice uses autoconf
-# First we need to configure for shared library mode (libngspice)
-export CFLAGS="-pthread"
-export CXXFLAGS="-pthread"
+# Set compiler flags based on debug mode
+if [ "${DEBUG_BUILD:-1}" = "1" ]; then
+    export CFLAGS="-g -O0 -pthread"
+    export CXXFLAGS="-g -O0 -pthread"
+    NGSPICE_DEBUG_FLAG="--enable-debug"
+else
+    export CFLAGS="-O2 -pthread"
+    export CXXFLAGS="-O2 -pthread"
+    NGSPICE_DEBUG_FLAG="--disable-debug"
+fi
 export LDFLAGS="-pthread"
 
 # Configure ngspice as a static library for WASM
@@ -67,7 +74,7 @@ emconfigure "${NGSPICE_DIR}/configure" \
     --build=$(uname -m)-linux-gnu \
     --disable-shared \
     --enable-static \
-    --disable-debug \
+    ${NGSPICE_DEBUG_FLAG} \
     --disable-dependency-tracking \
     --disable-openmp \
     --enable-cider \
diff --git a/scripts/deps/build-opencascade.sh b/scripts/deps/build-opencascade.sh
index 3b15d04..fa6dec8 100755
--- a/scripts/deps/build-opencascade.sh
+++ b/scripts/deps/build-opencascade.sh
@@ -61,10 +61,10 @@ cd "${OCC_BUILD}"
 # Enable core geometry and data exchange modules only
 emcmake cmake "${OCC_DIR}" \
     -DCMAKE_POLICY_VERSION_MINIMUM=3.5 \
-    -DCMAKE_BUILD_TYPE=Release \
+    -DCMAKE_BUILD_TYPE=${BUILD_TYPE:-Debug} \
     -DCMAKE_INSTALL_PREFIX="${SYSROOT}" \
-    -DCMAKE_CXX_FLAGS="-pthread -O2" \
-    -DCMAKE_C_FLAGS="-pthread -O2" \
+    -DCMAKE_CXX_FLAGS="${DEBUG_CFLAGS:--g -O0} -pthread" \
+    -DCMAKE_C_FLAGS="${DEBUG_CFLAGS:--g -O0} -pthread" \
     -DBUILD_LIBRARY_TYPE=Static \
     -DBUILD_MODULE_ApplicationFramework=OFF \
     -DBUILD_MODULE_Draw=OFF \
diff --git a/scripts/deps/build-pixman.sh b/scripts/deps/build-pixman.sh
index 7f4c815..06e9c60 100755
--- a/scripts/deps/build-pixman.sh
+++ b/scripts/deps/build-pixman.sh
@@ -52,6 +52,15 @@ log_info "Building Pixman ${PIXMAN_VERSION} for WASM..."
 mkdir -p "${PIXMAN_BUILD}"
 cd "${PIXMAN_BUILD}"
 
+# Determine meson build type based on DEBUG_BUILD
+if [ "${DEBUG_BUILD:-1}" = "1" ]; then
+    MESON_BUILD_TYPE="debug"
+    MESON_DEBUG_FLAGS="'-g', '-O0'"
+else
+    MESON_BUILD_TYPE="release"
+    MESON_DEBUG_FLAGS="'-O2'"
+fi
+
 # Pixman uses meson
 cat > cross-file.txt << EOF
 [binaries]
@@ -68,7 +77,7 @@ cpu = 'wasm32'
 endian = 'little'
 
 [built-in options]
-c_args = ['-pthread']
+c_args = [${MESON_DEBUG_FLAGS}, '-pthread']
 c_link_args = ['-pthread']
 EOF
 
@@ -76,11 +85,12 @@ meson setup "${PIXMAN_DIR}" \
     --cross-file cross-file.txt \
     --prefix="${SYSROOT}" \
     --default-library=static \
+    --buildtype=${MESON_BUILD_TYPE} \
     -Dgtk=disabled \
     -Dlibpng=disabled \
     -Dtests=disabled
 
-JOBS=${JOBS:-$(sysctl -n hw.ncpu 2>/dev/null || nproc 2>/dev/null || echo 4)}
+# JOBS is set in env.sh (default: 1 for sequential builds, use -j N to override)
 ninja -j${JOBS}
 ninja install
 
diff --git a/scripts/deps/build-protobuf.sh b/scripts/deps/build-protobuf.sh
index 3650913..85cf856 100755
--- a/scripts/deps/build-protobuf.sh
+++ b/scripts/deps/build-protobuf.sh
@@ -55,9 +55,10 @@ mkdir -p "${PROTOBUF_BUILD}"
 cd "${PROTOBUF_BUILD}"
 
 emcmake cmake "${PROTOBUF_DIR}" \
-    -DCMAKE_BUILD_TYPE=Release \
+    -DCMAKE_BUILD_TYPE=${BUILD_TYPE:-Debug} \
     -DCMAKE_INSTALL_PREFIX="${SYSROOT}" \
-    -DCMAKE_CXX_FLAGS="-pthread" \
+    -DCMAKE_C_FLAGS="${DEBUG_CFLAGS:--g -O0} -pthread" \
+    -DCMAKE_CXX_FLAGS="${DEBUG_CFLAGS:--g -O0} -pthread" \
     -Dprotobuf_BUILD_TESTS=OFF \
     -Dprotobuf_BUILD_EXAMPLES=OFF \
     -Dprotobuf_BUILD_PROTOC_BINARIES=OFF \
diff --git a/scripts/deps/build-zstd.sh b/scripts/deps/build-zstd.sh
index 828da64..0c1d4f5 100755
--- a/scripts/deps/build-zstd.sh
+++ b/scripts/deps/build-zstd.sh
@@ -54,7 +54,7 @@ cd "${ZSTD_BUILD}"
 
 # Zstd uses CMake in build/cmake directory
 emcmake cmake "${ZSTD_DIR}/build/cmake" \
-    -DCMAKE_BUILD_TYPE=Release \
+    -DCMAKE_BUILD_TYPE=${BUILD_TYPE:-Debug} \
     -DCMAKE_INSTALL_PREFIX="${SYSROOT}" \
     -DCMAKE_POLICY_VERSION_MINIMUM=3.5 \
     -DZSTD_BUILD_PROGRAMS=OFF \
@@ -62,8 +62,8 @@ emcmake cmake "${ZSTD_DIR}/build/cmake" \
     -DZSTD_BUILD_SHARED=OFF \
     -DZSTD_BUILD_STATIC=ON \
     -DZSTD_MULTITHREAD_SUPPORT=ON \
-    -DCMAKE_C_FLAGS="-pthread" \
-    -DCMAKE_CXX_FLAGS="-pthread"
+    -DCMAKE_C_FLAGS="${DEBUG_CFLAGS:--g -O0} -pthread" \
+    -DCMAKE_CXX_FLAGS="${DEBUG_CFLAGS:--g -O0} -pthread"
 
 emmake make -j${JOBS}
 emmake make install
diff --git a/scripts/kicad/build-pcbnew.sh b/scripts/kicad/build-pcbnew.sh
index 2ebd7a8..b7fff72 100755
--- a/scripts/kicad/build-pcbnew.sh
+++ b/scripts/kicad/build-pcbnew.sh
@@ -6,9 +6,12 @@
 #   ./scripts/kicad/build-pcbnew.sh [options]
 #
 # Options:
-#   --no-clean    Skip cleaning the build directory (default: clean before build)
+#   --clean       Full clean rebuild (dependencies + KiCad)
+#   --no-clean    Skip cleaning the build directory (default: clean KiCad only)
 #   --skip-deps   Skip building dependencies
-#   --debug       Build with debug symbols
+#   --debug       Build with debug symbols (default)
+#   --release     Build optimized without debug symbols
+#   -j N          Parallel compilation jobs (default: 1)
 
 set -e
 
@@ -23,26 +26,60 @@ KICAD_STAMP="${BUILD_ROOT}/stamps/kicad-pcbnew.stamp"
 WASM_LAYER="${PROJECT_ROOT}/wasm"
 WX_BUILD="${BUILD_ROOT}/wxwidgets-universal"
 
-# Parse arguments - clean by default
+# Parse arguments - clean KiCad by default
 NO_CLEAN=0
+FULL_CLEAN=0
 SKIP_DEPS=0
 DEBUG=0
-for arg in "$@"; do
-    case $arg in
+while [[ $# -gt 0 ]]; do
+    case $1 in
+        --clean)
+            FULL_CLEAN=1
+            shift
+            ;;
         --no-clean)
             NO_CLEAN=1
+            shift
             ;;
         --skip-deps)
             SKIP_DEPS=1
+            shift
             ;;
         --debug)
             DEBUG=1
+            shift
+            ;;
+        --release)
+            DEBUG_BUILD=0
+            export DEBUG_BUILD
+            shift
+            ;;
+        -j)
+            export JOBS="$2"
+            shift 2
+            ;;
+        -j*)
+            export JOBS="${1#-j}"
+            shift
+            ;;
+        *)
+            shift
             ;;
     esac
 done
 
-# Step 1: Clean build directory (default behavior)
-if [ $NO_CLEAN -eq 0 ]; then
+log_info "Using ${JOBS} parallel jobs"
+
+# Step 1: Clean build directories
+if [ $FULL_CLEAN -eq 1 ]; then
+    log_info "Full clean: removing all stamps and build directories..."
+    rm -rf "${STAMPS_DIR}"/*
+    rm -rf "${BUILD_ROOT}/deps"/*
+    rm -rf "${BUILD_ROOT}/wxwidgets-universal"
+    rm -rf "${BUILD_ROOT}/stubs"
+    rm -rf "${KICAD_BUILD}"
+    rm -rf "${SYSROOT}"/*
+elif [ $NO_CLEAN -eq 0 ]; then
     log_info "Cleaning KiCad PCBnew build directory..."
     rm -rf "${KICAD_BUILD}" "${KICAD_STAMP}"
 else
@@ -73,12 +110,17 @@ fi
 log_info "Building KiCad PCBnew ${KICAD_VERSION} for WASM..."
 
 # Step 5: Set build type
-if [ $DEBUG -eq 1 ]; then
+# Use environment DEBUG_BUILD if set, otherwise check local --debug flag
+if [ "${DEBUG_BUILD:-0}" = "1" ] || [ $DEBUG -eq 1 ]; then
     BUILD_TYPE="Debug"
     EXTRA_FLAGS="-g -O0"
+    LINKER_DEBUG_FLAGS="-g -gsource-map"
+    log_info "Building KiCad in DEBUG mode (with source maps)"
 else
     BUILD_TYPE="Release"
     EXTRA_FLAGS="-O2"
+    LINKER_DEBUG_FLAGS=""
+    log_info "Building KiCad in RELEASE mode"
 fi
 
 # Step 6: Create build directory
@@ -128,7 +170,7 @@ emcmake cmake "${KICAD_DIR}" \
     -DCMAKE_POLICY_VERSION_MINIMUM=3.5 \
     -DCMAKE_CXX_FLAGS="${EXTRA_FLAGS} -pthread -sUSE_ZLIB=1 -DKICAD_USE_PLATFORM_WASM=1 -I${SYSROOT}/include" \
     -DCMAKE_C_FLAGS="${EXTRA_FLAGS} -pthread -sUSE_ZLIB=1 -I${SYSROOT}/include" \
-    -DCMAKE_EXE_LINKER_FLAGS="-pthread -sUSE_ZLIB=1 -sASYNCIFY=1 -sASYNCIFY_STACK_SIZE=65536 -sUSE_PTHREADS=1 -sPTHREAD_POOL_SIZE=4 -sALLOW_MEMORY_GROWTH=1 -sINITIAL_MEMORY=256MB -sMAXIMUM_MEMORY=4GB -L${SYSROOT}/lib ${STUBS_BUILD}/libgit2_stub.a ${STUBS_BUILD}/libcurl_stub.a" \
+    -DCMAKE_EXE_LINKER_FLAGS="${LINKER_DEBUG_FLAGS} -pthread -sUSE_ZLIB=1 -sASYNCIFY=1 -sASYNCIFY_STACK_SIZE=65536 -sUSE_PTHREADS=1 -sPTHREAD_POOL_SIZE=4 -sALLOW_MEMORY_GROWTH=1 -sINITIAL_MEMORY=256MB -sMAXIMUM_MEMORY=4GB -L${SYSROOT}/lib ${STUBS_BUILD}/libgit2_stub.a ${STUBS_BUILD}/libcurl_stub.a" \
     -DCMAKE_PREFIX_PATH="${SYSROOT};${WX_BUILD}" \
     -DwxWidgets_CONFIG_EXECUTABLE="${WX_BUILD}/wx-config" \
     \
@@ -167,7 +209,7 @@ emcmake cmake "${KICAD_DIR}" \
 
 # Step 8: Build pcbnew target
 log_info "Building pcbnew..."
-JOBS=${JOBS:-$(sysctl -n hw.ncpu 2>/dev/null || nproc 2>/dev/null || echo 4)}
+# JOBS is set in env.sh (default: 1 for sequential builds, use -j N to override)
 emmake make -j${JOBS} pcbnew
 
 # Step 9: Create stamp file