diff --git a/.beads/interactions.jsonl b/.beads/interactions.jsonl
index 50d1f2f..d3ad111 100644
--- a/.beads/interactions.jsonl
+++ b/.beads/interactions.jsonl
@@ -1,2 +1,3 @@
 {"id":"int-691bec44","kind":"field_change","created_at":"2026-04-15T15:26:14.033393505Z","actor":"w1n5t0n","issue_id":"meml-kx6a","extra":{"field":"status","new_value":"in_progress","old_value":"open"}}
 {"id":"int-55a0a37d","kind":"field_change","created_at":"2026-04-15T15:32:17.624534929Z","actor":"w1n5t0n","issue_id":"meml-kx6a","extra":{"field":"status","new_value":"closed","old_value":"in_progress","reason":"Added firmware helper scripts and updated docs to the RP2350/C++20/O3 build flow"}}
+{"id":"int-c4271206","kind":"field_change","created_at":"2026-04-15T15:35:23.153751063Z","actor":"w1n5t0n","issue_id":"meml-efb2","extra":{"field":"status","new_value":"in_progress","old_value":"open"}}
diff --git a/CLAUDE.md b/CLAUDE.md
index 48220aa..cfb2d04 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -244,6 +244,9 @@ git submodule update --init --recursive
 # Build only
 scripts/build-firmware.sh
 
+# Build a specific variant
+scripts/build-firmware.sh memlcelium
+
 # Flash a previously-built UF2
 scripts/flash-firmware.sh
 
@@ -252,6 +255,7 @@ scripts/build-and-flash-firmware.sh
 ```
 
 The scripts build for `rp2040:rp2040:solderparty_rp2350_stamp_xl:opt=Optimize3` and force C++20 via `compiler.cpp.extra_flags=-std=gnu++20`.
+If no variant is passed to `build-firmware.sh` in an interactive shell, it parses the available `MEMLNautMode*` options from `MEMLNaut-NISPS.ino`, prompts for one, and rewrites the active `MEMLNAUT_MODE_TYPE` before compiling.
 
 ## Architecture
 
diff --git a/MAP.md b/MAP.md
index 5e69e7f..1c5c8bb 100644
--- a/MAP.md
+++ b/MAP.md
@@ -53,7 +53,7 @@ MEMLNaut-NISPS: Neural Interactive Shaping of Parameter Spaces. Two living artef
 - `README.md` — short quickstart.
 
 ## Entry points
-- **Firmware**: `scripts/build-firmware.sh`, `scripts/flash-firmware.sh`, or `scripts/build-and-flash-firmware.sh` (requires submodules initialised). The scripts target `rp2040:rp2040:solderparty_rp2350_stamp_xl:opt=Optimize3` and force C++20. Execution = `setup()`/`loop()` on Core 0, `setup1()`/`loop1()` on Core 1, audio ISR on Core 1.
+- **Firmware**: `scripts/build-firmware.sh`, `scripts/flash-firmware.sh`, or `scripts/build-and-flash-firmware.sh` (requires submodules initialised). `build-firmware.sh` can take an explicit variant name like `memlcelium` or prompt interactively from the parsed `MEMLNautMode*` list and rewrite the active mode in `MEMLNaut-NISPS.ino`. The scripts target `rp2040:rp2040:solderparty_rp2350_stamp_xl:opt=Optimize3` and force C++20. Execution = `setup()`/`loop()` on Core 0, `setup1()`/`loop1()` on Core 1, audio ISR on Core 1.
 - **Playground**: `cd playground && python3 -m http.server` (or `serve.sh` / `serve-coop.py`), open `a-immersive.html`. Append `?debug=1` to expose `window.__nisps`.
 - **WASM rebuild**: `cd playground/wasm && ./build.sh` (needs `emcc`).
 - **Tests**: `npx playwright test` (auto-spawns server on 7331).
diff --git a/README.md b/README.md
index 50a26f9..88e1913 100644
--- a/README.md
+++ b/README.md
@@ -18,6 +18,7 @@ scripts/build-and-flash-firmware.sh
 Notes:
 - The scripts build for `rp2040:rp2040:solderparty_rp2350_stamp_xl` with `Optimize3`.
 - The build forces C++20 because the firmware uses `std::span` and concepts.
+- `build-firmware.sh` accepts an optional variant name such as `memlcelium` or `breakor`. If you omit it in an interactive shell, the script parses `MEMLNaut-NISPS.ino`, prompts for a variant, and rewrites the active `MEMLNAUT_MODE_TYPE` before building.
 - `flash-firmware.sh` accepts an optional mountpoint argument, or auto-detects common UF2 bootloader mounts such as `/run/media/$USER/RP2350` and `/run/media/$USER/RPI-RP2`.
 
 ## Web Playground
diff --git a/scripts/build-and-flash-firmware.sh b/scripts/build-and-flash-firmware.sh
index 443e8da..831569c 100755
--- a/scripts/build-and-flash-firmware.sh
+++ b/scripts/build-and-flash-firmware.sh
@@ -7,7 +7,8 @@ usage() {
   cat <<'EOF'
 Usage:
   scripts/build-and-flash-firmware.sh
-  scripts/build-and-flash-firmware.sh [mountpoint]
+  scripts/build-and-flash-firmware.sh [variant]
+  scripts/build-and-flash-firmware.sh --variant VARIANT [mountpoint]
 
 If no mountpoint is provided, the flash step auto-detects a standard UF2
 bootloader location such as /run/media/$USER/RP2350 or /run/media/$USER/RPI-RP2.
@@ -19,21 +20,48 @@ if [[ "${1:-}" == "-h" || "${1:-}" == "--help" ]]; then
   exit 0
 fi
 
-case $# in
-  0)
-    ;;
-  1)
-    ;;
-  *)
-    usage >&2
-    exit 1
-    ;;
-esac
+source "$SCRIPT_DIR/firmware-common.sh"
+load_firmware_variants
 
-"$SCRIPT_DIR/build-firmware.sh"
+variant_arg="${MEMLNAUT_FIRMWARE_VARIANT:-}"
+mountpoint=""
 
-if [[ $# -eq 1 ]]; then
-  "$SCRIPT_DIR/flash-firmware.sh" "$1"
+while [[ $# -gt 0 ]]; do
+  case "$1" in
+    --variant)
+      if [[ $# -lt 2 ]]; then
+        echo "error: --variant requires a value" >&2
+        exit 1
+      fi
+      variant_arg="$2"
+      shift 2
+      ;;
+    --variant=*)
+      variant_arg="${1#*=}"
+      shift
+      ;;
+    *)
+      if [[ -z "$variant_arg" ]] && resolve_firmware_variant "$1" >/dev/null 2>&1; then
+        variant_arg="$1"
+      elif [[ -z "$mountpoint" ]]; then
+        mountpoint="$1"
+      else
+        usage >&2
+        exit 1
+      fi
+      shift
+      ;;
+  esac
+done
+
+if [[ -n "$variant_arg" ]]; then
+  "$SCRIPT_DIR/build-firmware.sh" --variant "$variant_arg"
+else
+  "$SCRIPT_DIR/build-firmware.sh"
+fi
+
+if [[ -n "$mountpoint" ]]; then
+  "$SCRIPT_DIR/flash-firmware.sh" "$mountpoint"
 else
   "$SCRIPT_DIR/flash-firmware.sh"
 fi
diff --git a/scripts/build-firmware.sh b/scripts/build-firmware.sh
index 4200090..af7e35d 100755
--- a/scripts/build-firmware.sh
+++ b/scripts/build-firmware.sh
@@ -8,9 +8,13 @@ source "$SCRIPT_DIR/firmware-common.sh"
 if [[ "${1:-}" == "-h" || "${1:-}" == "--help" ]]; then
   cat <<'EOF'
 Usage:
-  scripts/build-firmware.sh [extra arduino-cli compile args...]
+  scripts/build-firmware.sh [variant]
+  scripts/build-firmware.sh --variant VARIANT [extra arduino-cli compile args...]
+  scripts/build-firmware.sh [variant] -- [extra arduino-cli compile args...]
 
 Builds the MEMLNaut firmware with the repo's known-good RP2350 target and C++20 flag.
+If no variant is provided and the script is run in a TTY, it prompts from the parsed
+MEMLNaut mode list in MEMLNaut-NISPS.ino and rewrites the active mode before building.
 EOF
   exit 0
 fi
@@ -18,12 +22,49 @@ fi
 ensure_arduino_cli
 ensure_submodules_ready
 
+variant_arg="${MEMLNAUT_FIRMWARE_VARIANT:-}"
+compile_extra=()
+
+load_firmware_variants
+
+while [[ $# -gt 0 ]]; do
+  case "$1" in
+    --variant)
+      if [[ $# -lt 2 ]]; then
+        echo "error: --variant requires a value" >&2
+        exit 1
+      fi
+      variant_arg="$2"
+      shift 2
+      ;;
+    --variant=*)
+      variant_arg="${1#*=}"
+      shift
+      ;;
+    --)
+      shift
+      compile_extra+=("$@")
+      break
+      ;;
+    *)
+      if [[ -z "$variant_arg" ]] && resolve_firmware_variant "$1" >/dev/null 2>&1; then
+        variant_arg="$1"
+      else
+        compile_extra+=("$1")
+      fi
+      shift
+      ;;
+  esac
+done
+
+set_firmware_variant "$variant_arg"
 mkdir -p "$BUILD_DIR"
 
 echo "Building firmware:"
 echo "  sketch: $SKETCH_PATH"
 echo "  fqbn:   $FQBN"
 echo "  out:    $BUILD_DIR"
+echo "  variant: $(variant_alias "$ACTIVE_FIRMWARE_VARIANT")"
 
 compile_args=(
   compile
@@ -32,7 +73,7 @@ compile_args=(
   --output-dir "$BUILD_DIR"
   "$SKETCH_PATH"
 )
-compile_args+=("$@")
+compile_args+=("${compile_extra[@]}")
 
 arduino-cli "${compile_args[@]}"
 
diff --git a/scripts/firmware-common.sh b/scripts/firmware-common.sh
index a6cdace..d5737de 100755
--- a/scripts/firmware-common.sh
+++ b/scripts/firmware-common.sh
@@ -12,6 +12,9 @@ UF2_PATH_DEFAULT="${MEMLNAUT_FIRMWARE_UF2:-$BUILD_DIR/${SKETCH_NAME}.uf2}"
 FQBN="${MEMLNAUT_FIRMWARE_FQBN:-rp2040:rp2040:solderparty_rp2350_stamp_xl:opt=Optimize3}"
 CXX20_BUILD_PROPERTY="${MEMLNAUT_FIRMWARE_CXX20_PROPERTY:-compiler.cpp.extra_flags=-std=gnu++20}"
 
+FIRMWARE_VARIANTS=()
+ACTIVE_FIRMWARE_VARIANT=""
+
 ensure_arduino_cli() {
   if ! command -v arduino-cli >/dev/null 2>&1; then
     echo "error: arduino-cli is not installed or not on PATH" >&2
@@ -92,3 +95,143 @@ assert_boot_mount() {
     exit 1
   fi
 }
+
+load_firmware_variants() {
+  mapfile -t FIRMWARE_VARIANTS < <(
+    grep -E '^[[:space:]]*(//[[:space:]]*)?#define[[:space:]]+MEMLNAUT_MODE_TYPE[[:space:]]+MEMLNautMode[A-Za-z0-9_]+' "$SKETCH_PATH" \
+      | sed -E 's/^[[:space:]]*(\/\/[[:space:]]*)?#define[[:space:]]+MEMLNAUT_MODE_TYPE[[:space:]]+//'
+  )
+
+  if [[ ${#FIRMWARE_VARIANTS[@]} -eq 0 ]]; then
+    echo "error: could not find any MEMLNaut mode variants in $SKETCH_PATH" >&2
+    exit 1
+  fi
+
+  ACTIVE_FIRMWARE_VARIANT="$(
+    grep -E '^[[:space:]]*#define[[:space:]]+MEMLNAUT_MODE_TYPE[[:space:]]+MEMLNautMode[A-Za-z0-9_]+' "$SKETCH_PATH" \
+      | sed -E 's/^[[:space:]]*#define[[:space:]]+MEMLNAUT_MODE_TYPE[[:space:]]+//' \
+      | head -n 1
+  )"
+}
+
+variant_alias() {
+  local variant="$1"
+  variant="${variant#MEMLNautMode}"
+  printf '%s\n' "$variant" | tr '[:upper:]' '[:lower:]'
+}
+
+resolve_firmware_variant() {
+  local requested="$1"
+  local requested_lower
+  local variant
+
+  requested_lower="$(printf '%s' "$requested" | tr '[:upper:]' '[:lower:]')"
+  for variant in "${FIRMWARE_VARIANTS[@]}"; do
+    if [[ "$requested" == "$variant" || "$requested_lower" == "$(printf '%s' "$variant" | tr '[:upper:]' '[:lower:]')" || "$requested_lower" == "$(variant_alias "$variant")" ]]; then
+      printf '%s\n' "$variant"
+      return 0
+    fi
+  done
+
+  return 1
+}
+
+choose_firmware_variant() {
+  local requested="${1:-}"
+  local resolved=""
+  local variant
+  local choice
+
+  load_firmware_variants
+
+  if [[ -n "$requested" ]]; then
+    if resolved="$(resolve_firmware_variant "$requested")"; then
+      printf '%s\n' "$resolved"
+      return 0
+    fi
+
+    echo "error: unknown firmware variant: $requested" >&2
+    echo "available variants:" >&2
+    for variant in "${FIRMWARE_VARIANTS[@]}"; do
+      echo "  - $(variant_alias "$variant") ($variant)" >&2
+    done
+    exit 1
+  fi
+
+  if [[ -t 0 && -t 1 ]]; then
+    echo "Select a firmware variant to build:"
+    local idx=1
+    for variant in "${FIRMWARE_VARIANTS[@]}"; do
+      if [[ "$variant" == "$ACTIVE_FIRMWARE_VARIANT" ]]; then
+        echo "  $idx) $(variant_alias "$variant") ($variant, current)"
+      else
+        echo "  $idx) $(variant_alias "$variant") ($variant)"
+      fi
+      idx=$((idx + 1))
+    done
+
+    while true; do
+      read -r -p "Variant number or name: " choice
+      if [[ "$choice" =~ ^[0-9]+$ ]]; then
+        if (( choice >= 1 && choice <= ${#FIRMWARE_VARIANTS[@]} )); then
+          printf '%s\n' "${FIRMWARE_VARIANTS[choice-1]}"
+          return 0
+        fi
+      elif resolved="$(resolve_firmware_variant "$choice" 2>/dev/null)"; then
+        printf '%s\n' "$resolved"
+        return 0
+      fi
+      echo "Invalid selection. Enter a number from the list or a variant name."
+    done
+  fi
+
+  if [[ -n "$ACTIVE_FIRMWARE_VARIANT" ]]; then
+    echo "No variant specified and no interactive terminal available; using current variant: $(variant_alias "$ACTIVE_FIRMWARE_VARIANT")" >&2
+    printf '%s\n' "$ACTIVE_FIRMWARE_VARIANT"
+    return 0
+  fi
+
+  echo "error: no variant specified and no active variant found in $SKETCH_PATH" >&2
+  exit 1
+}
+
+set_firmware_variant() {
+  local requested="$1"
+  local selected
+
+  selected="$(choose_firmware_variant "$requested")"
+  python - "$SKETCH_PATH" "$selected" <<'PY'
+from pathlib import Path
+import re
+import sys
+
+sketch_path = Path(sys.argv[1])
+selected = sys.argv[2]
+
+pattern = re.compile(r'^(\s*)(//\s*)?#define(\s+MEMLNAUT_MODE_TYPE\s+)(MEMLNautMode[A-Za-z0-9_]+)(\s*)$')
+lines = sketch_path.read_text().splitlines()
+updated = []
+found_selected = False
+
+for line in lines:
+    match = pattern.match(line)
+    if not match:
+        updated.append(line)
+        continue
+
+    indent, _, middle, variant, trailing = match.groups()
+    if variant == selected:
+        updated.append(f"{indent}#define{middle}{variant}{trailing}")
+        found_selected = True
+    else:
+        updated.append(f"{indent}// #define{middle}{variant}{trailing}")
+
+if not found_selected:
+    raise SystemExit(f"selected variant not found in sketch: {selected}")
+
+sketch_path.write_text("\n".join(updated) + "\n")
+PY
+
+  ACTIVE_FIRMWARE_VARIANT="$selected"
+  echo "Selected firmware variant: $(variant_alias "$selected") ($selected)"
+}