Verify build mode transitions and propagate GUI job counts

tools/chatgui/build.sh

@@ -14,6 +14,18 @@ log ""
 SRC_DIR="$(cd "$(dirname "$0")" && pwd)"
 BUILD_DIR="$SRC_DIR/build"
 RUNTIME_PREFIX="${MSYSTEM_PREFIX:-/ucrt64}"
+JOBS=$(nproc 2>/dev/null || echo 4)
+while [[ $# -gt 0 ]]; do
+    case "$1" in
+        -j)
+            [[ $# -gt 1 ]] || { log "ERROR: -j requires a positive job count"; exit 1; }
+            shift; JOBS=$1 ;;
+        -j*) JOBS=${1#-j} ;;
+        *) log "ERROR: unknown argument: $1"; exit 1 ;;
+    esac
+    shift
+done
+[[ "$JOBS" =~ ^[1-9][0-9]*$ ]] || { log "ERROR: invalid job count: $JOBS"; exit 1; }
 
 log "Source:  $SRC_DIR"
 log "Build:   $BUILD_DIR"
@@ -36,7 +48,7 @@ if [ "${MSYSTEM:-}" = UCRT64 ]; then
         -DCMAKE_BUILD_TYPE=Release -DBUILD_SHARED_LIBS=ON 2>&1 | tee -a "$LOG_FILE" || {
         log "  ERROR: bundled rlottie configure failed"; exit 1;
     }
-    cmake --build "$SRC_DIR/rlottie_build" --target rlottie --parallel 4 2>&1 | tee -a "$LOG_FILE" || {
+    cmake --build "$SRC_DIR/rlottie_build" --target rlottie --parallel "$JOBS" 2>&1 | tee -a "$LOG_FILE" || {
         log "  ERROR: bundled rlottie build failed"; exit 1;
     }
     log "  OK: bundled rlottie ready in $SRC_DIR/rlottie_build"
@@ -47,7 +59,6 @@ cmake -S "$SRC_DIR" -B "$BUILD_DIR" -G Ninja 2>&1 | tee -a "$LOG_FILE"
 test ${PIPESTATUS[0]} -eq 0 || { log "CMake configure FAILED"; exit 1; }
 
 log ""
-JOBS=$(nproc 2>/dev/null || echo 4)
 log "[2/4] Building (parallel: $JOBS jobs)..."
 cmake --build "$BUILD_DIR" -j"$JOBS" 2>&1 | tee -a "$LOG_FILE"
 test ${PIPESTATUS[0]} -eq 0 || { log "Build FAILED"; exit 1; }