memlnaut-nisps/docs/specs/plans/feedback-modes-port-spec.md

kind	status
plan	executed

Implementation Spec — "Down Action" Negative-Feedback Feature in the nisps/ Core

Executed 2026-06/07; not authority for current behaviour. The port landed, then evolved past this document: the surviving truth is docs/adr/rl-feedback-design.md (which explicitly supersedes §2.5/§7's AVOID-out-of-scope decision — the geometric push WAS ported, via nisps/ml/geo_push.hpp + nisps/ml/replay.hpp) plus the code itself, nisps/ml/feedback.hpp (now FeedbackControllerCore<FbStorage>, storage-policied, with ExploreAndPlace added). The playground/ paths below refer to the retired SolidJS app (branch archive/playground-solidjs); the browser driver is now manifold/src/feedback/controller.ts.

0. Provenance

Every behavior below is read directly from local branch fork-feedback of the memllib submodule at /home/w1n5t0n/src/MEMLNaut-NISPS-upstream/:

• examples/InterfaceRL.hpp / .cpp — the FEEDBACK_MODE enum, all new state, all helpers.
• hardware/memlnaut/display/RLView.hpp — display only (out of scope for the core; informs JS only).
• modes/MEMLNautModeTR8S.hpp — selector + focus-mask wiring (activeDims_ source).

Target core read from /home/w1n5t0n/src/MEMLNaut-NISPS/: nisps/ml/{mlp,rl,init,training}.hpp, nisps/core/{concepts,perf,rng}.hpp, nisps/wasm/bindings.cpp, plus the JS driver (playground/src/modes/mode-runtime.ts, playground/src/ml/{wasm-iml.ts,types.ts}, playground/src/stores/exploration-store.ts) and the test/parity harness (tests/cpp/).

---

1. Exact behavior of all 3 modes (from the real source)

The original feature replaces a single "thumbs-down" semantic with three selectable behaviors. The selector is FEEDBACK_MODE (InterfaceRL.hpp):

enum class FEEDBACK_MODE : uint8_t {
    AVOID = 0,          // down = negative reward / geometric push away (current behaviour)
    RANDOMISE_OUTPUTS,  // down = bypass MLP, hold static random outputs (re-roll on each down); up = keep at current input
    RANDOMISE_MLP       // down = snapshot+randomise the live net (re-roll via left toggle); up/drag = keep & restore; down again = cancel
};

The exploration state, all private members in InterfaceRL:

FEEDBACK_MODE feedbackMode_ = FEEDBACK_MODE::AVOID;
bool explore_active_ = false;   // inside a RANDOMISE_OUTPUTS static hold or RANDOMISE_MLP temp net
bool learningPaused_ = false;   // optimise() suspended while exploring
std::vector<float> staticRandomOut_;     // held output in RANDOMISE_OUTPUTS
MLP<float>::mlp_weights weightSnapshot_; // original net, saved in RANDOMISE_MLP
std::vector<bool> activeDims_;           // focus mask (set by the mode; empty == all active)

There are exactly three event entry points, dispatched in loopCallback (thread context, never ISR):

• up = thumbs-up (MomA1) → _feedback_up()
• down = thumbs-down (MomA2) → _feedback_down()
• drag-store = joystick-click / Tog-A1 release → _feedback_drag_store()

Plus a fourth implicit transition: switching the mode while exploring → _abort_explore().

A critical cross-cutting fact: optimiseSometimes() early-returns when learningPaused_ is true, so training is fully suspended during any active exploration in modes 2 and 3.

1.1 Mode AVOID (FEEDBACK_MODE::AVOID) — historical behavior, unchanged

State machine is trivial — explore_active_/learningPaused_ are never touched.

Event	Action
up	_perform_like_action() — store +1 example at (controlInput, action); reset dislikeMultiplier_ = 1.
down	_perform_dislike_action() — store/strengthen a negative example (see below).
drag-store	storeExperience(1.f, controlInput, savedAction) — place the frozen output as a +1 example.

_perform_dislike_action() (InterfaceRL.cpp:41): scan replay memory; if a negative item exists within Euclidean distance 0.05 of controlInput, deepen it (reward = max(reward - 1, -kMaxDislikeMultiplier) where kMaxDislikeMultiplier = 16) instead of adding a duplicate; otherwise storeExperience(-1.f, ...). Then dislikeMultiplier_ = min(dislikeMultiplier_ * 2, 16).

The actual "push away" happens later in optimise() (InterfaceRL.cpp:717), not at press time. The geometric-push formula (the semantic that matters for reconciliation, §2.5):

// meanPositiveAction = mean of the kCentroidK (=4) positive memories
//                      nearest to controlInput (k-NN centroid).
float pushStep = std::clamp(fabsf(avgRewardNeg), 0.25f, 1.0f) * kGeometricPushScale; // kGeometricPushScale = 0.5
for (const auto& neg_action : tsNegative.second) {
    dir[j]  = neg_action[j] - meanPositiveAction[j];   // direction AWAY from positive centroid
    len     = ||dir||;
    const float effectivePushStep = pushStep / (1.0f + len);  // taper when already far
    // useRandom when len <= 1e-4 (degenerate: neg sits on the centroid)
    for each dim j with activeDims_[j]:
        float d = useRandom ? (rand&0xFF/127.5 - 1) : (dir[j]/len);
        target[j] = clamp(neg_action[j] + d * effectivePushStep, 0, 1);
    // train MLP toward `target` (push the disliked action away from the liked centroid)
}

So AVOID = "move the network's output at the disliked input geometrically away from the centroid of nearby liked outputs." Focus-aware: dims with activeDims_[j] == false are left untouched (if (!active) continue;).

1.2 Mode RANDOMISE_OUTPUTS (FEEDBACK_MODE::RANDOMISE_OUTPUTS)

Bypasses the MLP entirely and holds a static, hand-rolled output vector. The MLP and replay memory are not modified until commit.

Event	explore_active_ == false (idle)	explore_active_ == true (exploring)
down (1st)	_enter_randomise_outputs()	—
down (subsequent)	—	_roll_static_outputs() (re-roll)
up	_perform_like_action() (normal like)	_commit_explore(controlInput, action) (keep)
drag-store	normal +1 store	normal +1 store, stays in explore (keep re-rolling)

_enter_randomise_outputs() (InterfaceRL.cpp:150):

explore_active_ = true;
learningPaused_ = true;
staticRandomOut_ = action;   // seed inactive dims with current value
_roll_static_outputs();

_roll_static_outputs() — the randomisation formula (InterfaceRL.cpp:159):

if (staticRandomOut_.size() != action.size()) staticRandomOut_ = action;
for (size_t i = 0; i < staticRandomOut_.size(); i++) {
    const bool active = activeDims_.empty() || (i < activeDims_.size() && activeDims_[i]);
    if (active) staticRandomOut_[i] = static_cast<float>(rand() & 0xFFFF) / 65535.f; // uniform [0,1]
    // inactive dims keep their seeded entry value
}
newInput = true;

Per-dim: focused dims → fresh uniform [0,1]; unfocused dims → frozen at the value action had on entry. The held vector is emitted in generateAction() with no inference and no OU noise (InterfaceRL.cpp:998):

if (feedbackMode_ == FEEDBACK_MODE::RANDOMISE_OUTPUTS && explore_active_) {
    mappingOutput = staticRandomOut_;   // MLP bypassed
} else { /* GetOutput + OU noise + reflect-at-bounds */ }

_commit_explore(inputPos, outputVal) (InterfaceRL.cpp:188): storeExperience(1.f, inputPos, outputVal) then _restore_after_explore(). For OUTPUTS, outputVal == action, i.e. the static sound as currently heard becomes a +1 example at the current input, after which inference resumes.

_restore_after_explore() (InterfaceRL.cpp:194): for OUTPUTS it does not touch weights (no snapshot exists); it only learningPaused_ = false; explore_active_ = false; newInput = true;.

1.3 Mode RANDOMISE_MLP (FEEDBACK_MODE::RANDOMISE_MLP)

Snapshots the live weights, randomises the live net into a "temp net", and lets the user audition. Commit/restore swaps the original net back.

Event	explore_active_ == false (idle)	explore_active_ == true (exploring)
down (1st)	_enter_randomise_mlp()	—
down (subsequent)	—	_cancel_explore() (discard temp net, restore original)
re-roll	—	(firmware: left-toggle → randomiseTheNetwork(); not a _feedback_* hook)
up	_perform_like_action()	_commit_explore(controlInput, action) (keep)
drag-store	normal +1 store	+1 store and _restore_after_explore() (reposition-commit)

_enter_randomise_mlp() (InterfaceRL.cpp:170):

explore_active_ = true;
weightSnapshot_ = synthMapping->GetWeights();  // stash the REAL net
learningPaused_ = true;
randomiseTheNetwork();   // RandomiseWeightsAndBiasesLin(-0.9,1.1, -0.9,0.3); sets newInput

_cancel_explore() (InterfaceRL.cpp:179): SetWeights(weightSnapshot_) (discard temp), resume learning, clear flags.

_commit_explore() → storeExperience(1.f, controlInput, action) then _restore_after_explore(). For MLP, _restore_after_explore() restores the original net (SetWeights(weightSnapshot_)) — the just-stored example then trains the original net toward the auditioned output. So the temp net is never kept as-is; instead the example it produced is grafted onto the real net via training.

The drag-store interaction (_feedback_drag_store(), InterfaceRL.cpp:139) is the only place the drag is more than a plain store:

storeExperience(1.f, controlInput, savedAction);
_refresh_mem_counts();
if (feedbackMode_ == FEEDBACK_MODE::RANDOMISE_MLP && explore_active_) {
    _restore_after_explore();   // drag == reposition-commit
}

1.4 Forced teardown — _abort_explore() and mode switching

setFeedbackMode(m) (InterfaceRL.hpp): if (explore_active_) _abort_explore(); feedbackMode_ = m;. _abort_explore() is _restore_after_explore() minus the display calls: it restores the snapshot only in MLP mode, resumes learning, clears flags. This guarantees switching modes mid-exploration leaves the real net intact and learning resumed.

1.5 Focus-awareness summary (activeDims_)

activeDims_ is a std::vector<bool> set by the mode (setActiveDims). Empty ⇒ all dims active. It gates three places:

• AVOID geometric push: unfocused dims not pushed.
• RANDOMISE_OUTPUTS roll: unfocused dims frozen at entry value.
• (RANDOMISE_MLP has no per-dim focus — randomising weights affects all outputs; focus is only relevant via the output transform downstream.)

In TR-8S (MEMLNautModeTR8S.hpp) the mask is derived from a FocusManager<kN_Params, 12> (one group per drum voice + FX). This is mode/UI policy, not core logic.

---

2. Clean design for the new core component

2.1 Where the semantics diverge between old and new (must reconcile first)

Concept	Old (fork-feedback)	New core (nisps/ml/)
MLP type	MLP<float> runtime-sized, heap (std::vector, std::make_shared)	MLP<NIn,H1,H2,H3,NOut,...> compile-time, all std::array, zero heap
Weight snapshot	MLP<float>::mlp_weights (nested std::vector)	flat std::span<const float> from get_weights() (size weight_count())
RNG	global libc rand()	per-instance nisps::Rng (xoshiro256+), deterministic
Randomise net	RandomiseWeightsAndBiasesLin(-0.9,1.1,-0.9,0.3) (asymmetric uniform)	draw_weights(spread) (spread-aware Xavier↔uniform)
"Avoid"	geometric push toward/away centroid, deferred in optimise()	move_weights(speed, spread, pin_mask) = decay + Gaussian perturbation
Output buffer	std::vector<float> staticRandomOut_ runtime-sized	fixed std::array<float, NOut>
Training pause	learningPaused_ short-circuits optimise()	core has no training loop driver; pause must be a queryable flag the caller's train path honors

Recommendation for "Avoid" in the new core: Do not port the k-NN geometric centroid push. It depends on ReplayMemory<trainStatelessRLItem> (rewards, decay, accumulation) which is firmware-only and absent from nisps/. The new playground already implements AVOID as move_weights(cap, spread, pinMask) + noise growth (mode-runtime.ts::thumbsDown). Define Avoid in the new core as "delegate to the existing move_weights Gaussian perturbation." This is the documented parity contract in rl.hpp. The geometric-centroid behavior is a separate, richer algorithm that should be filed as a follow-up if desired — it is NOT part of this port, and the spec should say so explicitly. The FeedbackController's job for AVOID is purely to route to move_weights; it owns no AVOID-specific state.

This keeps the controller small: it only owns state for the two RANDOMISE modes.

2.2 Proposed component: nisps::ml::FeedbackController<MLP_T>

A header-only class template parameterized on the concrete MLP type, living at /home/w1n5t0n/src/MEMLNaut-NISPS/nisps/ml/feedback.hpp, namespace nisps::ml. It does not own the MLP; every mutating method takes MLP_T&. It owns only the exploration state. No virtual dispatch, no heap, per-instance RNG (its own, seeded independently from the MLP's so the static-output stream is reproducible without perturbing inference noise).

// nisps/ml/feedback.hpp
#pragma once
#include <array>
#include <cstdint>
#include <span>
#include "../core/perf.hpp"
#include "../core/rng.hpp"

namespace nisps::ml {

enum class FeedbackMode : std::uint8_t {
    Avoid           = 0,  // down → move_weights (Gaussian perturb). No internal state.
    RandomiseOutputs= 1,  // down → bypass MLP, hold static random vector; re-roll each down.
    RandomiseMlp    = 2,  // down → snapshot+draw_weights live net; down-again cancels.
};

// What a down/up/drag press resolved to — the caller (JS runtime / firmware glue)
// acts on this (store example, run move_weights, refresh UI). Keeps side effects
// that touch replay memory / training OUT of the core.
enum class FeedbackAction : std::uint8_t {
    None,
    AvoidPerturb,      // caller: run mlp.move_weights(speed, spread, pin) + grow noise
    LikeStore,         // caller: add +1 example at (input, output) + train
    EnterExplore,      // entered a RANDOMISE_* exploration (UI: show "exploring")
    Reroll,            // re-rolled within an exploration (UI feedback)
    CommitStore,       // caller: add +1 example at (input, current output), THEN explore ended
    Cancel,            // exploration discarded; net restored
    Restore,           // exploration kept (drag reposition path); net restored
};

template <typename MLP_T>
class FeedbackController {
   public:
    static constexpr std::size_t kNOut = MLP_T::kOutput;
    static constexpr std::size_t kWeights = MLP_T::weight_count();

    explicit FeedbackController(std::uint64_t seed) noexcept : rng_(seed) {}

    void set_mode(FeedbackMode m, MLP_T& mlp) noexcept {
        if (explore_active_) abort_explore(mlp);   // clean teardown on switch
        mode_ = m;
    }
    FeedbackMode mode() const noexcept { return mode_; }

    bool exploring()       const noexcept { return explore_active_; }
    bool learning_paused() const noexcept { return learning_paused_; }

    // Focus mask: 1 byte per output; mask[i]==0 means "frozen" (unfocused).
    // Empty span ⇒ all active. Copied into a fixed buffer (no heap, no dangling).
    void set_focus_mask(std::span<const std::uint8_t> mask) noexcept {
        focus_count_ = (mask.size() < kNOut) ? mask.size() : kNOut;
        for (std::size_t i = 0; i < focus_count_; ++i) focus_[i] = mask[i];
    }
    void clear_focus_mask() noexcept { focus_count_ = 0; }

    // --- press handlers. `current_out` is the live post-pipeline output the
    // user is hearing (NOut floats). They return a FeedbackAction telling the
    // caller what replay-memory / training side effect to perform. ---
    FeedbackAction on_down(MLP_T& mlp, std::span<const float> current_out,
                           float speed, float spread,
                           std::span<const std::uint8_t> pin_mask) noexcept;
    FeedbackAction on_up  (MLP_T& mlp) noexcept;
    FeedbackAction on_drag(MLP_T& mlp) noexcept;

    // Inference hook: returns true and fills `out` with the held static vector
    // when RandomiseOutputs is bypassing the MLP; returns false otherwise
    // (caller should run mlp.process() normally).
    bool static_output(std::span<float> out) const noexcept {
        if (!(mode_ == FeedbackMode::RandomiseOutputs && explore_active_)) return false;
        for (std::size_t i = 0; i < kNOut; ++i) out[i] = static_out_[i];
        return true;
    }

    void seed(std::uint64_t s) noexcept { rng_.seed(s); }

   private:
    void enter_randomise_outputs(std::span<const float> seed_out) noexcept {
        explore_active_ = true; learning_paused_ = true;
        for (std::size_t i = 0; i < kNOut; ++i) static_out_[i] = seed_out[i];
        roll_static_outputs();
    }
    void roll_static_outputs() noexcept {
        for (std::size_t i = 0; i < kNOut; ++i) {
            const bool active = (focus_count_ == 0u) || (i < focus_count_ && focus_[i] != 0u);
            if (active) static_out_[i] = rng_.next_float_uniform(); // [0,1) — see §2.4
        }
    }
    void enter_randomise_mlp(MLP_T& mlp, float spread) noexcept {
        explore_active_ = true; learning_paused_ = true;
        auto w = mlp.get_weights();                  // flat snapshot
        for (std::size_t i = 0; i < kWeights; ++i) snapshot_[i] = w[i];
        mlp.draw_weights(spread);                    // randomise live net
    }
    void restore_after_explore(MLP_T& mlp) noexcept {
        if (mode_ == FeedbackMode::RandomiseMlp)
            mlp.set_weights(std::span<const float>(snapshot_.data(), kWeights));
        learning_paused_ = false; explore_active_ = false;
    }
    void cancel_explore(MLP_T& mlp) noexcept {
        if (mode_ == FeedbackMode::RandomiseMlp)
            mlp.set_weights(std::span<const float>(snapshot_.data(), kWeights));
        learning_paused_ = false; explore_active_ = false;
    }
    void abort_explore(MLP_T& mlp) noexcept { cancel_explore(mlp); }

    FeedbackMode mode_ = FeedbackMode::Avoid;
    bool explore_active_  = false;
    bool learning_paused_ = false;
    std::array<float, kNOut>     static_out_{};
    std::array<float, kWeights>  snapshot_{};   // flat weight snapshot, no heap
    std::array<std::uint8_t, kNOut> focus_{};
    std::size_t focus_count_ = 0;               // 0 ⇒ all active
    Rng rng_;
};
}  // namespace nisps::ml

The press handlers mirror the old _feedback_up/_down/_drag_store switch exactly:

template <typename M>
FeedbackAction FeedbackController<M>::on_down(M& mlp, std::span<const float> current_out,
        float speed, float spread, std::span<const std::uint8_t> pin_mask) noexcept {
    switch (mode_) {
        case FeedbackMode::Avoid:
            mlp.move_weights(speed, spread, pin_mask);   // AVOID == perturb (see §2.5)
            return FeedbackAction::AvoidPerturb;
        case FeedbackMode::RandomiseOutputs:
            if (!explore_active_) { enter_randomise_outputs(current_out); return FeedbackAction::EnterExplore; }
            roll_static_outputs();                       return FeedbackAction::Reroll;
        case FeedbackMode::RandomiseMlp:
            if (!explore_active_) { enter_randomise_mlp(mlp, spread); return FeedbackAction::EnterExplore; }
            cancel_explore(mlp);                         return FeedbackAction::Cancel;
    }
    return FeedbackAction::None;
}

template <typename M>
FeedbackAction FeedbackController<M>::on_up(M& mlp) noexcept {
    if ((mode_ == FeedbackMode::RandomiseOutputs || mode_ == FeedbackMode::RandomiseMlp) && explore_active_) {
        restore_after_explore(mlp);     // caller stores +1 at (input, current_out) FIRST
        return FeedbackAction::CommitStore;
    }
    return FeedbackAction::LikeStore;   // AVOID up, or idle RANDOMISE up
}

template <typename M>
FeedbackAction FeedbackController<M>::on_drag(M& mlp) noexcept {
    if (mode_ == FeedbackMode::RandomiseMlp && explore_active_) {
        restore_after_explore(mlp);
        return FeedbackAction::Restore;  // caller already stored the +1 from savedAction
    }
    return FeedbackAction::LikeStore;    // plain drag-store
}

Note the ordering contract: in the old _commit_explore, storeExperience runs before _restore_after_explore (so in MLP mode the example is captured from the temp net's output, then the original net is restored and trained). The new core encodes this as: on_up returns CommitStore and the caller must add the example using the output it captured before calling on_up (which is exactly the live current_out). Document this loudly at the call site.

2.3 Why a "FeedbackController" and not an MLP/engine extension

• The MLP must stay a pure numeric kernel. It already satisfies MLEngine (concepts.hpp) with no notion of "exploration", "focus", or "modes". Bolting feedback state onto MLP would (a) inflate weight_count()-sized snapshot storage onto every MLP instance even when unused, and (b) couple the parity/golden vectors to UI policy. Keep it separate.
• The controller is the natural home for the snapshot because the snapshot size is MLP_T::weight_count() — known at compile time, so a std::array works and the no-heap rule is honored.
• It composes: firmware modes and the WASM handle both already hold an MLP; they add one FeedbackController next to it.

2.4 RNG reconciliation

Old _roll_static_outputs uses rand() & 0xFFFF / 65535.f (libc, non-deterministic, global). New core uses the per-instance Rng. Two choices for the static-output stream:

• Recommended: the controller owns its own Rng rng_ seeded separately. Rationale: re-rolling outputs must not advance the MLP's inference/move RNG (that would make inference noise depend on how many times the user pressed "down"), and a separate stream makes the OUTPUTS path independently reproducible in tests. rng_.next_float_uniform() already returns [0,1) — semantically equivalent to the old [0, 65535]/65535 up to the endpoint and resolution, well within parity tolerance because this value is generated, not compared against the MLP.
• For RANDOMISE_MLP, draw_weights(spread) uses the MLP's RNG (correct — it's the net being randomised), matching how nisps_ml_draw_weights already advances the MLP stream.

2.5 AVOID reconciliation, restated as a decision

move_weights (Gaussian decay+perturb) and the old geometric centroid push are different algorithms. The new playground already shipped AVOID-as-move_weights. Therefore:

• FeedbackController::Avoid routes on_down → mlp.move_weights(speed, spread, pin_mask) and returns AvoidPerturb. It carries no replay memory and no centroid math.
• The richer geometric-push avoidance (with ReplayMemory, reward decay, k-NN centroid) is explicitly out of scope for this port; if wanted later it belongs in a separate replay-memory component, not the FeedbackController. Flag this in ALIGNMENT.md as an accepted divergence so a future session doesn't "rediscover" it as a bug.

---

3. The C++/JS boundary — what lives where

Lives in C++ (FeedbackController, shared with firmware):

• mode_ enum, explore_active_, learning_paused_.
• static_out_ buffer (NOut floats) + the re-roll formula + the bypass-inference hook.
• snapshot_ flat weights + snapshot/restore/cancel via get_weights/set_weights.
• focus mask (NOut bytes) + the focus-gated roll.
• The on_down/up/drag state-transition logic and the FeedbackAction it returns.

Stays in the SolidJS runtime (inherently UI / orchestration):

• Which input/output vector to store as the example (depends on the pipeline-processed outputs, overrides, mic features) — mode-runtime.ts::thumbsUp/thumbsDown already computes these.
• When to train, the LR, snapshot stack for undo (autoSnapshot), noise growth/decay (exploration-store.ts).
• Building the pin_mask (buildPinMask from overrides + param pins).
• Display strings, "Down Action" selector widget, toasts. (RLView in firmware is the analogous display — out of core scope.)
• The replay-memory / example dataset itself stays caller-side (the JS Dataset + the MLP's own ring buffer).

Max-sharing principle honored: all the fiddly state-machine logic (the part with off-by-one re-roll/cancel/commit bugs) is shared C++; only data the core cannot know (pipeline outputs, pins, UI) stays in JS. The boundary is "the controller decides what transition happened; the caller decides what to persist."

The JS runtime keeps learning_paused() honored by gating its trainOnCurrent() and auto-explore tick: when paused, skip training (mirrors optimiseSometimes()'s early return).

---

4. WASM C API additions

Add to nisps/wasm/bindings.cpp. The MLHandle gains a FeedbackController next to its DefaultMLP (FeedbackController<DefaultMLP>), seeded off the same JS seed XOR a salt so its stream is independent of the MLP's:

// inside struct MLHandle:
nisps::ml::FeedbackController<DefaultMLP> feedback;
std::array<float, kDefaultOutputs> static_out_scratch{};   // for nisps_ml_feedback_static_output
explicit MLHandle(std::uint64_t seed) noexcept
    : mlp(seed), feedback(seed ^ 0xFEEDBACC0DEull) {}

New extern "C" functions (all EMSCRIPTEN_KEEPALIVE):

// Mode + state.
void   nisps_ml_feedback_set_mode(void* ml, int mode);             // 0=Avoid 1=RandOut 2=RandMlp
int    nisps_ml_feedback_get_mode(void* ml);
int    nisps_ml_feedback_exploring(void* ml);                      // 0/1
int    nisps_ml_feedback_learning_paused(void* ml);                // 0/1

// Focus mask (NOut bytes; pass nullptr/0 to clear).
void   nisps_ml_feedback_set_focus(void* ml, const uint8_t* mask, int n);

// Press handlers. `current_out` = NOut floats the user is hearing.
// `pin_mask` may be null. Return value is the FeedbackAction enum (int) so JS
// knows what to persist (store example / perturb / commit / cancel).
int    nisps_ml_feedback_down(void* ml, const float* current_out,
                              float speed, float spread, const uint8_t* pin_mask);
int    nisps_ml_feedback_up(void* ml);
int    nisps_ml_feedback_drag(void* ml);

// Inference hook: if returns 1, `out` (NOut floats) holds the static bypass
// vector and the caller should NOT call nisps_ml_process(); if 0, run process().
int    nisps_ml_feedback_static_output(void* ml, float* out);

Representative implementation (matches the existing guard/cast style in bindings.cpp):

EMSCRIPTEN_KEEPALIVE
int nisps_ml_feedback_down(void* ml, const float* current_out,
                           float speed, float spread, const uint8_t* pin_mask) {
    if (!ml) return 0;
    auto* h = static_cast<MLHandle*>(ml);
    std::span<const float> out = current_out
        ? std::span<const float>(current_out, kDefaultOutputs) : std::span<const float>{};
    std::span<const std::uint8_t> mask = pin_mask
        ? std::span<const std::uint8_t>(pin_mask, kDefaultOutputs) : std::span<const std::uint8_t>{};
    return static_cast<int>(h->feedback.on_down(h->mlp, out, speed, spread, mask));
}

TS FFI declarations to add to playground/src/ml/types.ts (NispsModule interface, mirroring the existing _nisps_ml_* block):

// Feedback / Down-Action.
_nisps_ml_feedback_set_mode(ml: number, mode: number): void;
_nisps_ml_feedback_get_mode(ml: number): number;
_nisps_ml_feedback_exploring(ml: number): number;
_nisps_ml_feedback_learning_paused(ml: number): number;
_nisps_ml_feedback_set_focus(ml: number, mask_ptr: number, n: number): void;
_nisps_ml_feedback_down(ml: number, current_out_ptr: number, speed: number, spread: number, pin_mask_ptr: number): number;
_nisps_ml_feedback_up(ml: number): number;
_nisps_ml_feedback_drag(ml: number): number;
_nisps_ml_feedback_static_output(ml: number, out_ptr: number): number;

Plus a FeedbackAction / FeedbackMode TS enum in types.ts mirroring the C++ enums (numeric values must match). WasmIML (wasm-iml.ts) gains thin wrappers (feedbackDown(currentOut, speed, spread, pinMask), etc.) that reuse the existing pinMaskBuf and add a small static_out heap buffer; the parity .mjs shim adds cwrap bindings for the same names.

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5. Test plan

5.1 Host ctest — new file tests/cpp/test_mlp_feedback.cpp

Register it in the nisps_core_tests executable in nisps/CMakeLists.txt (it links nisps_core, builds under -Wall -Wextra -Werror -Wpedantic). Use the existing harness (NISPS_TEST / NISPS_EXPECT / NISPS_EXPECT_NEAR) and a small MLP like the existing RL test (MLP<2,4,4,4,6,8,32>). Because the controller takes MLP_T&, instantiate FeedbackController<SmallMLP>.

Cases (one NISPS_TEST each):

1. feedback_avoid_routes_to_move_weights — mode Avoid; snapshot weights; on_down(...) returns AvoidPerturb and weights changed (most distinct), mirroring mlp_move_weights_changes_unpinned_weights. exploring() stays false; learning_paused() stays false.
2. feedback_randout_enter_roll_state — mode RandomiseOutputs; on_down (1st) → EnterExplore, exploring()==true, learning_paused()==true; static_output(buf) returns true and buf differs from current_out on focused dims.
3. feedback_randout_reroll_changes_focused_only — set focus mask {1,0,1,0,1,0}; enter; capture static; on_down again → Reroll; assert unfocused dims unchanged (frozen at seed value), focused dims changed.
4. feedback_randout_commit_clears_state — while exploring, on_up → CommitStore, then exploring()==false, learning_paused()==false, static_output() returns false (MLP no longer bypassed). Weights unchanged (OUTPUTS never touches the net).
5. feedback_randmlp_snapshot_and_cancel_restores — mode RandomiseMlp; snapshot weights W0 (via get_weights); on_down (1st) → EnterExplore, weights now differ from W0; on_down again → Cancel; get_weights() byte-equals W0 (exact ==).
6. feedback_randmlp_commit_restores_then_caller_trains — enter; on_up → CommitStore; assert net restored to W0 (the kept example is the caller's responsibility; here we assert the restore semantics: post-commit weights == W0).
7. feedback_randmlp_drag_repositions — enter; on_drag → Restore, net restored to W0, exploring()==false.
8. feedback_mode_switch_aborts_explore — enter RandomiseMlp; set_mode(Avoid, mlp) → net restored to W0, exploring()==false, learning_paused()==false.
9. feedback_determinism_fixed_seed — two FeedbackControllers with the same seed, same MLP-seed, identical press sequence (enter RandomiseOutputs, two re-rolls) → static_output buffers byte-identical. Proves per-instance RNG determinism (no libc rand()).
10. feedback_focus_empty_means_all_active — no focus mask set; enter RandomiseOutputs; all NOut dims changed from a fixed seed-vector of constants.
11. feedback_static_output_bypass_only_in_randout — static_output() returns false in Avoid and in idle RandomiseOutputs, true only when RandomiseOutputs && exploring.

5.2 Native↔WASM parity

Extend the standalone parity runner in lock-step (parity_check.cpp + parity_wasm.mjs), appending a feedback block to the existing payload after the current stages (bump kVersion to 2 in both files and parity_diff.mjs if it checks version). Deterministic sequence, identical on both sides:

// Stage 5 (feedback): with the SAME ParityMLP, after stage-2 training:
//   feedback.set_mode(RandomiseOutputs)
//   feedback.on_down(current_out = stage-2 outputs, speed=0.1, spread=0.5, pin=null)  → EnterExplore
//   feedback.static_output(buf)  → push 126 floats
//   feedback.on_down(... )       → Reroll
//   feedback.static_output(buf)  → push 126 floats
//   feedback.set_mode(RandomiseMlp); feedback.on_down(...) (enter, draws weights)
//   push 12 probed weights of the now-randomised temp net
//   feedback.on_up()             → CommitStore (restores)
//   push 12 probed weights of the restored net  (must equal pre-explore probes)

The controller must be seeded identically in parity_check.cpp and parity_wasm.mjs (e.g. seed kSeed ^ 0xFEEDBACC0DE, matching the MLHandle salt). scripts/parity-check.sh already float32-diffs at 1e-5 — the new floats are covered automatically. The RandomiseOutputs static vectors are RNG output (not compared against the MLP), so as long as both sides run the same nisps::Rng from the same seed they match exactly; the RandomiseMlp restore-probes prove get_weights/set_weights round-trips identically across native/WASM.

5.3 Existing suites

nisps_core_tests, nisps_dsp_engine_tests, nisps_modes_tests, nisps_golden_tests are unaffected (controller is additive). bash scripts/run-all-tests.sh (chokepoint E) gains the new ctest case and the extended parity blob. No hardware is exercised.

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6. Firmware note — feasibility

The same FeedbackController<MLP_T> drops into a firmware mode unchanged, because it honors every rule in the RP2350 performance contract (CLAUDE.md):

• No heap: static_out_, snapshot_, focus_ are all std::array sized from MLP_T::weight_count() / kOutput at compile time. No std::vector, no make_shared (unlike the old mlp_weights).
• No virtual dispatch: plain class template; press handlers are direct calls.
• Deterministic per-instance RNG: uses nisps::Rng, constructed with a seed.
• .f literals / NISPS_* attrs: the controller's hot path is trivial (a loop over NOut); mark roll_static_outputs/static_output NISPS_FORCE_INLINE and any audio-touched members NISPS_AUDIO_MEM if a firmware mode reads static_out_ from the audio core (it would not — feedback runs on the control/UI core, like the old loopCallback).

Wiring in a future firmware mode (analogous to the TR-8S bind_RL_interface callbacks):

• MomA1 (up) handler → set a volatile pendingUp_ flag; control loop calls controller.on_up(mlp) and, on CommitStore/LikeStore, adds the example to whatever replay/dataset the firmware mode keeps.
• MomA2 (down) → pendingDown_ → controller.on_down(mlp, current_out, speed, spread, pin).
• Joystick-click / Tog-A1 release → pendingDrag_ → controller.on_drag(mlp).
• The mode's per-sample/synth output path checks controller.static_output(buf): if true, emit buf (bypass), else run the MLP — exactly the generateAction() branch at InterfaceRL.cpp:998.
• The mode's training tick checks controller.learning_paused() and skips training when true (mirrors optimiseSometimes() early-return).
• The "Down Action" RotarySelectView calls controller.set_mode(m, mlp) (the old addFeedbackModeView).

All handlers run in thread/control context (never ISR), identical to the original which dispatched everything via deferred flags in loopCallback. No new locking is needed beyond the mode's existing mlpActive spin-lock around get_weights/set_weights/draw_weights — the same lock the old code held around optimise()/generateAction().

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7. File-touch summary (implementation-ready)

File	Change
/home/w1n5t0n/src/MEMLNaut-NISPS/nisps/ml/feedback.hpp	NEW — FeedbackMode, FeedbackAction, FeedbackController<MLP_T> (as in §2.2).
/home/w1n5t0n/src/MEMLNaut-NISPS/nisps/wasm/bindings.cpp	Add FeedbackController<DefaultMLP> + static_out_scratch to MLHandle; add 9 nisps_ml_feedback_* C functions (§4).
/home/w1n5t0n/src/MEMLNaut-NISPS/playground/src/ml/types.ts	Add 9 _nisps_ml_feedback_* to NispsModule; add FeedbackMode/FeedbackAction enums.
/home/w1n5t0n/src/MEMLNaut-NISPS/playground/src/ml/wasm-iml.ts	Thin wrapper methods + a small static-output heap buffer; reuse pinMaskBuf.
/home/w1n5t0n/src/MEMLNaut-NISPS/playground/src/modes/mode-runtime.ts	Route thumbsDown through the controller per active mode; gate training on learning_paused().
/home/w1n5t0n/src/MEMLNaut-NISPS/playground/src/stores/exploration-store.ts	Add feedbackMode + exploring UI state (selector + indicator).
/home/w1n5t0n/src/MEMLNaut-NISPS/tests/cpp/test_mlp_feedback.cpp	NEW — 11 ctest cases (§5.1).
/home/w1n5t0n/src/MEMLNaut-NISPS/nisps/CMakeLists.txt	Add test_mlp_feedback.cpp to nisps_core_tests.
/home/w1n5t0n/src/MEMLNaut-NISPS/tests/cpp/parity_check.cpp + parity_wasm.mjs	Append feedback Stage 5; bump version to 2 (§5.2).

Key reconciliation decisions to record in ALIGNMENT.md

1. AVOID in the new core = move_weights Gaussian perturbation (the new playground's existing behavior), not the old k-NN geometric centroid push (which depended on firmware-only ReplayMemory and is out of scope). Accepted divergence.
2. RANDOMISE_OUTPUTS static vector uses the controller's own nisps::Rng (deterministic, per-instance) instead of libc rand() — endpoint/resolution differ trivially from [0,65535]/65535 but the value is generated, not compared.
3. RANDOMISE_MLP randomisation uses draw_weights(spread) (spread-aware) instead of the old asymmetric RandomiseWeightsAndBiasesLin(-0.9,1.1,-0.9,0.3). If the asymmetric distribution matters perceptually, that's a follow-up draw_weights_range(lo,hi) primitive — not part of this port.