diff --git a/.beads/interactions.jsonl b/.beads/interactions.jsonl
index e69de29..50d1f2f 100644
--- a/.beads/interactions.jsonl
+++ b/.beads/interactions.jsonl
@@ -0,0 +1,2 @@
+{"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"}}
diff --git a/CLAUDE.md b/CLAUDE.md
index d96ff9c..48220aa 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -235,17 +235,24 @@ Tests use the `?debug=1` probe (`window.__nisps`) for programmatic access to the
 
 ## Build System
 
-This is an Arduino project targeting Raspberry Pi Pico. Build and upload using Arduino IDE or arduino-cli with the earlephilhower/pico board package.
+This is an Arduino project targeting the MEMLNaut RP2350 hardware. Build and flash it with the repo-local helper scripts, which wrap the correct board target and compiler settings.
 
 ```bash
 # Initialize submodules (required for memllib and memlp)
 git submodule update --init --recursive
 
-# Build (adjust port as needed)
-arduino-cli compile --fqbn rp2040:rp2040:rpipico -b 115200 MEMLNaut-NISPS.ino
-arduino-cli upload --fqbn rp2040:rp2040:rpipico -p /dev/ttyACM0 MEMLNaut-NISPS.ino
+# Build only
+scripts/build-firmware.sh
+
+# Flash a previously-built UF2
+scripts/flash-firmware.sh
+
+# Build then flash
+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`.
+
 ## Architecture
 
 ### Dual-Core Design
diff --git a/MAP.md b/MAP.md
new file mode 100644
index 0000000..5e69e7f
--- /dev/null
+++ b/MAP.md
@@ -0,0 +1,95 @@
+# MAP
+
+MEMLNaut-NISPS: Neural Interactive Shaping of Parameter Spaces. Two living artefacts share one ML core: (1) Arduino/RP2040 firmware for the MEMLNaut hardware, and (2) a browser playground that uses a WASM build of the same MLP to drive a C15 synth + other outputs. A header-only `nisps-core/` extraction is reused by the playground (via WASM bindings) and a VCV Rack module. See `CLAUDE.md` for the long-form architecture narrative.
+
+## Layout
+
+### Firmware (Arduino, RP2040)
+- `MEMLNaut-NISPS.ino` — top-level sketch; dual-core setup, mode selected at compile-time via `#define MEMLNAUT_MODE_TYPE`.
+- `IMLInterface.hpp` — interactive ML controller; wraps MLP + RL with STORE_VALUE / STORE_POSITION modes.
+- `modes/MEMLNautMode.hpp` — concept/contract satisfied by each mode class.
+- `modes/MEMLNautMode*.hpp` — mode implementations (PAFSynth, ChannelStrip, XIASRI, SoundAnalysisMIDI, VerbFX, BreakOr, Elysiamorfs).
+- `modes/AudioApps/` — audio engines used by the newer modes (VerbFX, BreakOr, Elysiamorf, RatioSeq).
+- `PAFSynthAudioApp.hpp`, `ChannelStripAudioApp.hpp`, `ThruAudioApp.hpp`, `XIASRIAudioApp.hpp` — older audio engines at the repo root.
+- `XiasriAnalysis.{hpp,cpp}` — real-time audio feature extraction (pitch, aperiodicity, brightness, etc.).
+- `voicespaces/` — lambdas mapping MLP output vectors to synth parameters. Subdir `ChannelStrip/` for EQ/comp presets.
+- `src/memllib/`, `src/memlp/` — git submodules (hardware abstraction + MLP). **Not auto-initialized** — build breaks without `git submodule update --init --recursive`.
+- `src/daisysp/` — vendored DSP library (filters, drums, effects).
+- `data/` — preset/asset CSVs.
+
+### nisps-core (platform-agnostic C++20 header-only)
+- `nisps-core/include/nisps/` — `iml.hpp`, `mlp.hpp`, `layer.hpp`, `node.hpp`, `dataset.hpp`, `loss.hpp`, `utils.hpp`.
+- `nisps-core/test/`, `nisps-core/examples/`, `nisps-core/README.md`, `CHANGELOG.md`.
+
+### Playground (browser ML demo)
+- `playground/index.html` — hub linking to the three variants.
+- `playground/a-immersive.html` + `js/a-app.js` — **primary** app. WASM engine, full control surface, modular/engine-switcher, C15 + MIDI + audio-canvas outputs.
+- `playground/b-workbench.html` + `js/b-app.js`, `c-journey.html` + `js/c-app.js` — older variants on the legacy JS engine. Feature-frozen; drift vs. a-app is intentional (see `CLAUDE.md` memory on `playground/RECONCILIATION.md` — note: file does **not** currently exist).
+- `playground/designs.html`, `js/app.js` — oldest experimental app. Kept for reference.
+- `playground/wasm/` — Emscripten build: `nisps_bindings.cpp` (C API, float32), `build.sh`, compiled `nisps.wasm`/`nisps.js`.
+- `playground/js/nisps/` — `nisps-wasm.js` (WasmIML wrapper), `nisps-wasm-worker.js` (off-thread train), `dataset.js` (FIFO ring buffer, max 100), legacy pure-JS engine (`iml.js`, `mlp.js`, `layer.js`, `node.js`) used by b/c apps.
+- `playground/js/synth/` — `c15-bridge.js`, `param-map.js` (126 curated C15 params), `presets.js` (4 tiers), `arpeggiator.js`.
+- `playground/js/ui/` — UI modules. Categories:
+  - Input: `input-pipeline.js`, `joystick.js`, `joy-map-enhanced.js`, `gamepad.js`, `hand-tracker.js`, `eoc-*.js`.
+  - Control surface: `control-surface.js`, `control-surface-ui.js` (3 compound axes: Boldness / Memory / Precision).
+  - Training/exploration: `snapshot-stack.js`, `ab-compare.js`, `region-pin.js`, `param-pin.js`, `auto-explore.js`, `pressure-feedback.js`, `input-heatmap.js`.
+  - Output/debug: `output-pipeline.js`, `weight-health.js`, `gradient-flow.js`, `session-presets.js`, `visualizer.js`, `param-display.js`, `dev-panel.js`.
+  - Phase wiring: `phase2-ui.js`, `phase3-ui.js`, `phase4-ui.js`.
+  - Modular mode: `modular-ui.js` (~52k, large), `engine-switcher.js` — newer; not yet documented in `CLAUDE.md`.
+- `playground/c15/`, `playground/faust/`, `playground/osc-bridge/` — external synth/bridge assets.
+- `playground/SPEC-controls.md`, `SPEC-shapeseq.md`, `ARCHITECTURE.md`, `PLAN-solidjs-migration.md`, `TODOS.md`, `README.md`, `devlog/` — docs.
+
+### Other consumers
+- `vcv/` — VCV Rack plugin using `nisps-core` (`src/MEMLNaut.cpp`, `SPEC.md`, `NISPS-FORMAT.md`).
+
+### Tests
+- `tests/e2e/*.spec.js` — Playwright e2e against the immersive app via the `?debug=1` probe (`window.__nisps`). Covers ml-engine, wasm-api, ui-interactions, input-pipeline, persistence, engine-switching, modular-mode. Shared helpers in `tests/e2e/helpers.js`.
+- `playwright.config.js`, `package.json` — auto-starts a static server on port 7331.
+
+### Top-level docs / planning
+- `CLAUDE.md` — architecture narrative for both firmware and playground.
+- `AGENTS.md` — beads/bd conventions.
+- `NISPS_CORE_EXTRACTION_PLAN.md`, `NISPS_CORE_TASKS.md` — extraction task list; status unclear, likely stale now that `nisps-core/` exists.
+- `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.
+- **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).
+- **VCV module**: built inside `vcv/` with the VCV Rack SDK.
+
+## Conventions
+- Firmware mode selection is compile-time only; only one `MEMLNAUT_MODE_TYPE` uncommented at a time in `MEMLNaut-NISPS.ino`.
+- RP2040 memory placement via `APP_SRAM`, `AUDIO_MEM`, `AUDIO_FUNC`, `__not_in_flash("app")`. Audio hot paths use `__force_inline` / `__hot` / `__flatten`.
+- Cross-core sync: `MEMORY_BARRIER()`, `WRITE_VOLATILE`/`READ_VOLATILE`, RP2040 `queue_t`.
+- Voice spaces are header-only structs whose mappings are lambdas capturing synth state — **implicit coupling** to synth members.
+- Playground ML engines (`IML`, `WasmIML`) share a duck-typed interface (`inference`, `train`, `getWeights`/`setWeights`, …); WASM uses **float32**, JS engine uses float64.
+- `Dataset` is a **FIFO ring buffer**, default max 100 examples; recency/spatial sample weighting is computed JS-side.
+- Spread-aware weight init / RL noise (`drawWeightsSpread`, `moveWeightsEx`) live in `playground/wasm/nisps_bindings.cpp`, **not** in `nisps-core` proper — they are playground-specific.
+- Playground UI modules dispatch `controlsurface:change` CustomEvents; `a-app.js` listens and reconfigures the input pipeline, spread, and RL params.
+- URL params: `?tame`, `?spread`, `?preset`, `?debug=1`, `?shapeseq=1`.
+- Persistent memory (`bd remember`) notes:
+  - ShapeSeq is gated behind `?shapeseq=1` until solid — arp remains default.
+  - ShapeSeq MLP plan is **switchable mode** (unified single-MLP first, then dual-MLP option).
+  - `playground/RECONCILIATION.md` is supposed to track features landed in a-app but not yet in b/c. File does not currently exist — if you add a-only features, either create it or explicitly accept the drift.
+
+## Gotchas
+- `memllib` and `memlp` submodules are **not auto-checked-out** — a fresh clone will fail to compile the firmware silently.
+- Double-scaled loss: C++ `Train()` and WASM `train_ex` both divide by `n` when no sample weights are supplied (known, backward-compat, tracked as `meml-ues`).
+- `VerbFXAudioApp` / `MEMLNautModeVerbFX` have **entire analysis blocks commented out** — the mode was migrated from analysis-driven to joystick-driven and cleanup is unfinished. Don't assume XiasriAnalysis wiring is live there.
+- `XiasriAnalysis` output struct is union-cast to a float array inside XIASRI mode — fragile if the struct layout changes.
+- Recent fixes cluster around the modular voice: matrix rebuild, `mod_amp` positive-only floor, MLP bypass when untrained, worklet blob-url registration — modular mode is under active churn, so expect rough edges.
+- `a-app.js` is the single source of truth. **Do not** reflexively mirror changes to `b-app.js` / `c-app.js` — they are frozen legacy variants.
+- `window.__nisps` only exists with `?debug=1`; Playwright helpers expect this.
+
+## Open questions / smells
+- `modular-ui.js` is ~52k and undocumented in `CLAUDE.md`; needs a `docs/modular.md` stub, especially given recent bug cluster.
+- `engine-switcher.js` + `engine-switching.spec.js` + `modular-mode.spec.js` — newer engine-selection mechanism not described in `CLAUDE.md`. Verify whether there is now a supported alternative engine besides WASM-MLP.
+- `playground/RECONCILIATION.md` is referenced by persistent memory but missing on disk. Either the memory is stale or the file needs creating.
+- `NISPS_CORE_TASKS.md` / `NISPS_CORE_EXTRACTION_PLAN.md` at the repo root likely describe completed work — candidates for deletion or archiving under `docs/history/`.
+- `PLAN-solidjs-migration.md` (34k) describes an unstarted rewrite. Either flag it "aspirational / not started" at the top or move to `docs/`.
+- No `README.md` for `playground/wasm/` — a 10-line binding table (C API ↔ JS wrapper ↔ nisps-core call) would save future agents a trip through `nisps_bindings.cpp`.
+- Firmware `IMLInterface`'s STORE_VALUE vs STORE_POSITION modes have no docs — decide which modes use which and document.
+- Global `std::shared_ptr<MIDIInOut>` in the sketch introduces refcount traffic on the 1 ms MIDI poll — likely benign, worth confirming.
+- Two duplicated CLAUDE.md copies at `~/.claude/CLAUDE.md` and `~/.claude-gp/CLAUDE.md` (symlinked), and a per-repo one — not a repo smell, just noted so future agents don't try to "reconcile".
diff --git a/README.md b/README.md
index 343f605..50a26f9 100644
--- a/README.md
+++ b/README.md
@@ -2,6 +2,24 @@
 
 https://musicallyembodiedml.github.io/memlnaut/approaches/nisps
 
+## Firmware
+
+The hardware firmware targets the MEMLNaut RP2350 build and uses repo-local helper
+scripts for the known-good build configuration:
+
+```bash
+git submodule update --init --recursive
+
+scripts/build-firmware.sh
+scripts/flash-firmware.sh
+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.
+- `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
 
 Try NISPS in your browser — no hardware required:
diff --git a/scripts/build-and-flash-firmware.sh b/scripts/build-and-flash-firmware.sh
new file mode 100755
index 0000000..443e8da
--- /dev/null
+++ b/scripts/build-and-flash-firmware.sh
@@ -0,0 +1,39 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+
+usage() {
+  cat <<'EOF'
+Usage:
+  scripts/build-and-flash-firmware.sh
+  scripts/build-and-flash-firmware.sh [mountpoint]
+
+If no mountpoint is provided, the flash step auto-detects a standard UF2
+bootloader location such as /run/media/$USER/RP2350 or /run/media/$USER/RPI-RP2.
+EOF
+}
+
+if [[ "${1:-}" == "-h" || "${1:-}" == "--help" ]]; then
+  usage
+  exit 0
+fi
+
+case $# in
+  0)
+    ;;
+  1)
+    ;;
+  *)
+    usage >&2
+    exit 1
+    ;;
+esac
+
+"$SCRIPT_DIR/build-firmware.sh"
+
+if [[ $# -eq 1 ]]; then
+  "$SCRIPT_DIR/flash-firmware.sh" "$1"
+else
+  "$SCRIPT_DIR/flash-firmware.sh"
+fi
diff --git a/scripts/build-firmware.sh b/scripts/build-firmware.sh
new file mode 100755
index 0000000..4200090
--- /dev/null
+++ b/scripts/build-firmware.sh
@@ -0,0 +1,41 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+# shellcheck source=./firmware-common.sh
+source "$SCRIPT_DIR/firmware-common.sh"
+
+if [[ "${1:-}" == "-h" || "${1:-}" == "--help" ]]; then
+  cat <<'EOF'
+Usage:
+  scripts/build-firmware.sh [extra arduino-cli compile args...]
+
+Builds the MEMLNaut firmware with the repo's known-good RP2350 target and C++20 flag.
+EOF
+  exit 0
+fi
+
+ensure_arduino_cli
+ensure_submodules_ready
+
+mkdir -p "$BUILD_DIR"
+
+echo "Building firmware:"
+echo "  sketch: $SKETCH_PATH"
+echo "  fqbn:   $FQBN"
+echo "  out:    $BUILD_DIR"
+
+compile_args=(
+  compile
+  --fqbn "$FQBN"
+  --build-property "$CXX20_BUILD_PROPERTY"
+  --output-dir "$BUILD_DIR"
+  "$SKETCH_PATH"
+)
+compile_args+=("$@")
+
+arduino-cli "${compile_args[@]}"
+
+echo
+echo "UF2 ready at:"
+echo "  $UF2_PATH_DEFAULT"
diff --git a/scripts/firmware-common.sh b/scripts/firmware-common.sh
new file mode 100755
index 0000000..a6cdace
--- /dev/null
+++ b/scripts/firmware-common.sh
@@ -0,0 +1,94 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+REPO_ROOT="$(cd "$SCRIPT_DIR/.." && pwd)"
+
+SKETCH_PATH="${MEMLNAUT_FIRMWARE_SKETCH:-$REPO_ROOT/MEMLNaut-NISPS.ino}"
+SKETCH_NAME="$(basename "$SKETCH_PATH")"
+BUILD_DIR="${MEMLNAUT_FIRMWARE_BUILD_DIR:-/tmp/memlnaut-firmware-build}"
+UF2_PATH_DEFAULT="${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}"
+
+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
+    exit 1
+  fi
+}
+
+ensure_git() {
+  if ! command -v git >/dev/null 2>&1; then
+    echo "error: git is not installed or not on PATH" >&2
+    exit 1
+  fi
+}
+
+ensure_submodules_ready() {
+  ensure_git
+
+  local status
+  status="$(git -C "$REPO_ROOT" submodule status --recursive)"
+  if grep -qE '^[+-]' <<<"$status"; then
+    echo "error: submodules are not initialized or not at the recorded revision" >&2
+    echo "run: git submodule update --init --recursive" >&2
+    exit 1
+  fi
+}
+
+resolve_path() {
+  local path="$1"
+
+  if [[ "$path" = /* ]]; then
+    printf '%s\n' "$path"
+  else
+    printf '%s\n' "$(pwd)/$path"
+  fi
+}
+
+find_boot_mount() {
+  local candidates=(
+    "/run/media/${USER}/RP2350"
+    "/run/media/${USER}/RPI-RP2"
+    "/media/${USER}/RP2350"
+    "/media/${USER}/RPI-RP2"
+    "/mnt/RP2350"
+    "/mnt/RPI-RP2"
+  )
+  local candidate
+
+  for candidate in "${candidates[@]}"; do
+    if [[ -d "$candidate" ]]; then
+      printf '%s\n' "$candidate"
+      return 0
+    fi
+  done
+
+  local base
+  for base in "/run/media/${USER}" "/media/${USER}" "/mnt"; do
+    [[ -d "$base" ]] || continue
+    candidate="$(find "$base" -maxdepth 2 -type f -name INFO_UF2.TXT -printf '%h\n' 2>/dev/null | head -n 1 || true)"
+    if [[ -n "$candidate" ]]; then
+      printf '%s\n' "$candidate"
+      return 0
+    fi
+  done
+
+  return 1
+}
+
+assert_boot_mount() {
+  local mountpoint="$1"
+
+  if [[ ! -d "$mountpoint" ]]; then
+    echo "error: bootloader mount does not exist: $mountpoint" >&2
+    exit 1
+  fi
+
+  if [[ ! -f "$mountpoint/INFO_UF2.TXT" && ! -f "$mountpoint/INDEX.HTM" ]]; then
+    echo "error: $mountpoint does not look like an RP2040/RP2350 UF2 boot volume" >&2
+    exit 1
+  fi
+}
diff --git a/scripts/flash-firmware.sh b/scripts/flash-firmware.sh
new file mode 100755
index 0000000..b614417
--- /dev/null
+++ b/scripts/flash-firmware.sh
@@ -0,0 +1,77 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+# shellcheck source=./firmware-common.sh
+source "$SCRIPT_DIR/firmware-common.sh"
+
+usage() {
+  cat <<'EOF'
+Usage:
+  scripts/flash-firmware.sh
+  scripts/flash-firmware.sh [mountpoint]
+  scripts/flash-firmware.sh [uf2-path] [mountpoint]
+
+Defaults:
+  uf2-path   -> /tmp/memlnaut-firmware-build/MEMLNaut-NISPS.ino.uf2
+  mountpoint -> auto-detect from standard UF2 bootloader locations
+EOF
+}
+
+uf2_path="$UF2_PATH_DEFAULT"
+mountpoint=""
+
+if [[ "${1:-}" == "-h" || "${1:-}" == "--help" ]]; then
+  usage
+  exit 0
+fi
+
+case $# in
+  0)
+    ;;
+  1)
+    if [[ -f "$1" || "$1" == *.uf2 ]]; then
+      uf2_path="$1"
+    else
+      mountpoint="$1"
+    fi
+    ;;
+  2)
+    uf2_path="$1"
+    mountpoint="$2"
+    ;;
+  *)
+    usage >&2
+    exit 1
+    ;;
+esac
+
+uf2_path="$(resolve_path "$uf2_path")"
+if [[ ! -f "$uf2_path" ]]; then
+  echo "error: UF2 file not found: $uf2_path" >&2
+  echo "run scripts/build-firmware.sh first, or pass an explicit UF2 path" >&2
+  exit 1
+fi
+
+if [[ -z "$mountpoint" ]]; then
+  mountpoint="$(find_boot_mount || true)"
+fi
+
+if [[ -z "$mountpoint" ]]; then
+  echo "error: could not find a mounted UF2 bootloader volume" >&2
+  echo "put the board in bootloader mode or pass the mountpoint explicitly" >&2
+  exit 1
+fi
+
+mountpoint="$(resolve_path "$mountpoint")"
+assert_boot_mount "$mountpoint"
+
+echo "Flashing firmware:"
+echo "  uf2:       $uf2_path"
+echo "  mountpoint: $mountpoint"
+
+cp "$uf2_path" "$mountpoint/"
+sync
+
+echo
+echo "Flash copy completed."