diff --git a/.gitignore b/.gitignore
index ffa6182..6f59050 100644
--- a/.gitignore
+++ b/.gitignore
@@ -50,3 +50,6 @@ node_modules/
 bun.lock
 playwright-report/
 test-results/
+
+# Agent worktrees
+.claude/worktrees/
diff --git a/MAP.md b/MAP.md
index 4a98d78..335f354 100644
--- a/MAP.md
+++ b/MAP.md
@@ -40,7 +40,7 @@ MEMLNaut-NISPS — Neural Interactive Shaping of Parameter Spaces. One C++20 cod
 - `playground/src/input/pipeline.ts`, `playground/src/output/pipeline.ts`, `playground/src/output/curves.ts` — pure-fn pipelines (deadzone→zoom→curve→smoothing→momentum, then global curve→smoothing→slew→freeze).
 - `playground/src/features/` — additional feature modules (heatmap sampling, snapshot stack, A/B compare, region pin, param pin, trail, weight health, etc.).
 - `playground/src/debug/probe.ts` — synchronous `window.__nisps` debug probe for Playwright.
-- `playground/public/nisps.{wasm,js}`, `c15.wasm`, `c15-glue.js` — compiled WASM artifacts (built by `scripts/build-wasm.sh`).
+- `playground/public/nisps.{wasm,js}`, `c15.wasm`, `c15-glue.js` — WASM artifacts. `nisps.*` are a transitional copy from `scripts/build-wasm.sh` (canonical output is `manifold/public/`; copy dies with playground at P1).
 - `playground/tests/e2e/` — Playwright specs (`ml-engine`, `modes`, `persistence`, `ui-interactions`) + `helpers.ts`.
 - `playground/playwright.config.ts` — Vite preview server setup.
 
@@ -113,7 +113,7 @@ the "BUILD DELTAS" block at the top of `docs/specs/vcv-module.md`). `src/MEMLNau
 
 ### `scripts/` — build + verify entry points
 - `build-firmware.sh`, `flash-firmware.sh`, `build-and-flash-firmware.sh`, `firmware-common.sh` — Arduino-CLI wrapper for RP2350 target with C++20 flag.
-- `build-wasm.sh` — Emscripten compile producing `playground/public/nisps.{wasm,js}`.
+- `build-wasm.sh` — Emscripten compile producing `manifold/public/nisps.{wasm,js}` (+ transitional copy to `playground/public/` until P1).
 - `build-cpp-tests.sh` — CMake configure + build + ctest (Ninja).
 - `parity-check.sh` — runs native + WASM and diffs binary outputs.
 - `lint-cpp.sh` — `.f` literal warn + heap/`Arduino.h` violation fail.
diff --git a/docs/AGENT-REFERENCE.md b/docs/AGENT-REFERENCE.md
index 9d99966..bb5acd7 100644
--- a/docs/AGENT-REFERENCE.md
+++ b/docs/AGENT-REFERENCE.md
@@ -124,9 +124,9 @@ Two WASM instances at runtime:
 1. **Main thread** (`playground/src/ml/wasm-iml.ts`): ML inference + sync training + RL primitives. Update store after each call. Async training via disposable Web Worker (`wasm-worker.ts`).
 2. **AudioWorklet** (`playground/src/audio/worklet/nisps-processor.ts`): runs engine `process_block` per audio block. Loads `nisps.wasm` directly via `WebAssembly.compile` (no Emscripten glue in worklet). Bytes posted from main thread.
 
-C API is in `nisps/wasm/bindings.cpp`. Build: `bash scripts/build-wasm.sh` (~94KB output to `playground/public/`).
+C API is in `nisps/wasm/bindings.cpp`. Build: `bash scripts/build-wasm.sh` (~94KB output to `manifold/public/`, transitional copy to `playground/public/` until P1).
 
-The WASM target is fixed at `MLP<2, 10, 14, 18, 126>`. Modes with smaller `output_size` use the first N outputs only.
+The WASM target is fixed at `MLP<32u, 10u, 14u, 18u, 126u>` (`nisps_ml_create` ignores requested dims — see `docs/specs/plans/one-core-engine-refactor.md` P2). Modes with smaller `input_size`/`output_size` use a slice.
 
 ### Known limitations
 
diff --git a/docs/specs/plans/one-core-engine-refactor.md b/docs/specs/plans/one-core-engine-refactor.md
index 7547f16..8bbbd4e 100644
--- a/docs/specs/plans/one-core-engine-refactor.md
+++ b/docs/specs/plans/one-core-engine-refactor.md
@@ -74,13 +74,13 @@ skin) still applies inside manifold; this plan adds the vertical one.
 Each phase ends green on its test gate and is independently landable. File phases as **ergo** tasks
 (one per phase, sub-tasks per bullet); do not start a phase before its predecessor's gate is green.
 
-### P0 — Plumbing hygiene (hours, no behaviour change)
+### P0 — Plumbing hygiene (hours, no behaviour change) — ✅ landed 2026-07-13
 
-- `scripts/build-wasm.sh` emits to `manifold/public/` (keep `playground/public/` copy only until P1 lands).
-- `scripts/parity-check.sh` reads the manifold artifact.
-- Fix stale doc: `MAP.md` §WASM still says `MLP<2,…>`; code is `MLP<32u,10u,14u,18u,126u>`.
-- Delete `ml-debug.log`, `graphify-out/` from tree root; gitignore `.claude/worktrees/`.
-- **Gate:** `run-all-tests.sh` green; manifold builds against a freshly-built (not copied) `nisps.wasm`.
+- ✅ `scripts/build-wasm.sh` emits to `manifold/public/` (keep `playground/public/` copy only until P1 lands).
+- ✅ `scripts/parity-check.sh` (and `tests/cpp/parity_wasm.mjs`) read the manifold artifact.
+- ✅ Fix stale doc: the `MLP<2,…>` line was in `docs/AGENT-REFERENCE.md` + `nisps/wasm/README.md` (MAP.md was already correct); both now say `MLP<32u,10u,14u,18u,126u>`.
+- ✅ `ml-debug.log`/`graphify-out/` were already absent from the tree; `.claude/worktrees/` gitignored.
+- **Gate met:** `run-all-tests.sh` green (Playwright leg via the BUILD-PLAN non-snap-node VPS runner); parity PASS reading `manifold/public/` (max delta 2.4e-7); manifold typecheck+build green against the freshly-built artifact.
 
 ### P1 — Retire playground, single TS home (≈1 day)
 
diff --git a/manifold/public/nisps.wasm b/manifold/public/nisps.wasm
index 9ee47b2..cf9dbdb 100755
Binary files a/manifold/public/nisps.wasm and b/manifold/public/nisps.wasm differ
diff --git a/nisps/wasm/README.md b/nisps/wasm/README.md
index 0ce7871..07f0d68 100644
--- a/nisps/wasm/README.md
+++ b/nisps/wasm/README.md
@@ -1,11 +1,13 @@
 # nisps/wasm
 
 Emscripten target that exposes `nisps/ml` (MLP) and `nisps/engines` (audio
-engines) to the SolidJS playground via a flat C ABI.
+engines) to the browser apps via a flat C ABI.
 
 This directory is a leaf — it does not export headers for inclusion by
 other C++ code. The only artifact is `bindings.cpp` plus the build script
-that turns it into `playground/public/nisps.{wasm,js}`.
+that turns it into `manifold/public/nisps.{wasm,js}` (with a transitional
+copy to `playground/public/` until P1 of
+`docs/specs/plans/one-core-engine-refactor.md` retires the playground).
 
 ## Building
 
@@ -18,11 +20,11 @@ Requires `emcc` (Emscripten). The script defaults to
 
 Output:
 
-- `playground/public/nisps.wasm` — the compiled module.
-- `playground/public/nisps.js`  — Emscripten glue (factory function
+- `manifold/public/nisps.wasm` — the compiled module.
+- `manifold/public/nisps.js`  — Emscripten glue (factory function
   `createNispsModule`, MODULARIZE=1).
 
-Both files are committed (so the playground works from a fresh clone
+Both files are committed (so the browser apps work from a fresh clone
 without a C++ toolchain). Re-run `build-wasm.sh` after changes to
 `nisps/{core,ml,engines,wasm}`.
 
@@ -32,9 +34,9 @@ The MLP class template is parametrised on `(input_size, hidden1, hidden2,
 hidden3, output_size)`. WASM cannot recompile templates at runtime, so
 this build instantiates exactly ONE configuration:
 
-    nisps::ml::MLP<2, 10, 14, 18, 126>
+    nisps::ml::MLP<32, 10, 14, 18, 126>
 
-That serves the playground use case (2-D joystick → up to 126 synth
+That serves the browser use case (up to 32 input axes → up to 126 synth
 parameters). `nisps_ml_create()` accepts caller-supplied dimensions for
 forward compatibility but currently ignores them — see comment at the top
 of `bindings.cpp`. The schemas in `schemas/modes/*.json` use up to
diff --git a/playground/public/nisps.wasm b/playground/public/nisps.wasm
index 9ee47b2..cf9dbdb 100755
Binary files a/playground/public/nisps.wasm and b/playground/public/nisps.wasm differ
diff --git a/scripts/build-wasm.sh b/scripts/build-wasm.sh
index 28db680..aac7dde 100755
--- a/scripts/build-wasm.sh
+++ b/scripts/build-wasm.sh
@@ -1,6 +1,6 @@
 #!/usr/bin/env bash
 # scripts/build-wasm.sh — compile nisps/wasm/bindings.cpp via Emscripten and
-# write the result to playground/public/.
+# write the result to manifold/public/.
 #
 # Requires emcc. Defaults to /usr/lib/emscripten/emcc; override via the EMCC
 # env var. Sample invocation:
@@ -8,14 +8,17 @@
 #     EMCC=$(which emcc) scripts/build-wasm.sh
 #
 # Output:
-#   playground/public/nisps.js     — Emscripten glue, MODULARIZE factory
-#   playground/public/nisps.wasm   — the compiled module
+#   manifold/public/nisps.js     — Emscripten glue, MODULARIZE factory
+#   manifold/public/nisps.wasm   — the compiled module
+#
+# A copy is also written to playground/public/ until P1 of
+# docs/specs/plans/one-core-engine-refactor.md retires the playground.
 
 set -euo pipefail
 
 EMCC="${EMCC:-$(command -v emcc || echo /usr/lib/emscripten/emcc)}"
 ROOT="$(cd "$(dirname "$0")/.." && pwd)"
-OUT="$ROOT/playground/public"
+OUT="$ROOT/manifold/public"
 SRC="$ROOT/nisps/wasm/bindings.cpp"
 
 if [[ ! -x "$EMCC" && ! -f "$EMCC" ]]; then
@@ -82,3 +85,10 @@ set -x
 
 echo "[build-wasm] wrote $OUT/nisps.js + $OUT/nisps.wasm"
 ls -lh "$OUT/nisps.js" "$OUT/nisps.wasm"
+
+# Transitional copy for the playground; removed when P1 deletes playground/.
+PLAYGROUND_OUT="$ROOT/playground/public"
+if [[ -d "$PLAYGROUND_OUT" ]]; then
+  command cp -f "$OUT/nisps.js" "$OUT/nisps.wasm" "$PLAYGROUND_OUT/"
+  echo "[build-wasm] copied artifacts to $PLAYGROUND_OUT (transitional, until P1)"
+fi
diff --git a/scripts/parity-check.sh b/scripts/parity-check.sh
index 12f594c..4b543e5 100755
--- a/scripts/parity-check.sh
+++ b/scripts/parity-check.sh
@@ -4,7 +4,7 @@
 #
 # Prerequisites:
 #   1. scripts/build-cpp-tests.sh has run (need nisps_parity_check binary).
-#   2. scripts/build-wasm.sh has run (need playground/public/nisps.{js,wasm}).
+#   2. scripts/build-wasm.sh has run (need manifold/public/nisps.{js,wasm}).
 #
 # This script can run either step on demand if the artifacts are missing.
 # Skip auto-build with NISPS_PARITY_NO_BUILD=1.
@@ -21,8 +21,8 @@ ROOT="$(cd "$(dirname "$0")/.." && pwd)"
 TESTS_DIR="$ROOT/tests/cpp"
 BUILD_DIR="${NISPS_BUILD_DIR:-$ROOT/nisps/build}"
 NATIVE_BIN="$BUILD_DIR/nisps_parity_check"
-WASM_GLUE="$ROOT/playground/public/nisps.js"
-WASM_MOD="$ROOT/playground/public/nisps.wasm"
+WASM_GLUE="$ROOT/manifold/public/nisps.js"
+WASM_MOD="$ROOT/manifold/public/nisps.wasm"
 NATIVE_OUT="$TESTS_DIR/parity_native.bin"
 WASM_OUT="$TESTS_DIR/parity_wasm.bin"
 TOL="${NISPS_PARITY_TOL:-1e-5}"
diff --git a/tests/cpp/parity_wasm.mjs b/tests/cpp/parity_wasm.mjs
index afa3f7b..b8e75da 100644
--- a/tests/cpp/parity_wasm.mjs
+++ b/tests/cpp/parity_wasm.mjs
@@ -4,7 +4,7 @@
  * parity_check.cpp against the WASM build of nisps and writes a binary blob
  * with identical layout. The shell wrapper compares the two blobs.
  *
- * The WASM module is loaded from playground/public/nisps.{js,wasm} —
+ * The WASM module is loaded from manifold/public/nisps.{js,wasm} —
  * scripts/build-wasm.sh must have run first.
  *
  * Output blob format matches parity_check.cpp:
@@ -48,7 +48,7 @@ const SYNTH_FRAMES = 128;
 const PROBE_IDX    = [0, 5, 19, 31, 73, 137, 251, 491, 999, 1583, 2401, 3289];
 
 async function loadWasm() {
-  const wasmGluePath = resolve(repoRoot, 'playground', 'public', 'nisps.js');
+  const wasmGluePath = resolve(repoRoot, 'manifold', 'public', 'nisps.js');
   try {
     await access(wasmGluePath, fsConstants.R_OK);
   } catch {
@@ -59,7 +59,7 @@ async function loadWasm() {
   // The Emscripten glue is generated with MODULARIZE=1, which writes
   //   var createNispsModule = (() => ...)();
   //   if (typeof exports==='object' && typeof module==='object') module.exports = ...;
-  // It lives in playground/public/, which is a sub-package with
+  // It lives in manifold/public/, which is a sub-package with
   // "type":"module" in its parent package.json — so neither `require()` nor
   // `import()` can extract the factory cleanly. We work around this by
   // reading the file as text and evaluating it inside a thin shim that
@@ -77,7 +77,7 @@ async function loadWasm() {
     console.error('[parity_wasm] could not locate createNispsModule in glue');
     process.exit(2);
   }
-  const wasmBinaryPath = resolve(repoRoot, 'playground', 'public', 'nisps.wasm');
+  const wasmBinaryPath = resolve(repoRoot, 'manifold', 'public', 'nisps.wasm');
   const wasmBinary = await readFile(wasmBinaryPath);
   const Module = await factory({ wasmBinary });
   return Module;