"""Schema25 Torch GDN2 trajectory state, processor, and memory readers."""

from __future__ import annotations

from collections.abc import Sequence
from dataclasses import dataclass, replace
import weakref
import math

import torch
from torch import nn
from torch.nn import functional as F

from .gdn2_trajectory import GDN2TrajectoryMemory, GDN2TrajectoryState


COMMIT_REASON_NONE = 0
COMMIT_REASON_NORMAL = 1
COMMIT_REASON_FORCED_JUMP = 2
COMMIT_REASON_TERMINAL = 3


def _sdpa_mask_value(dtype: torch.dtype) -> float:
    """Additive SDPA mask that stays finite on MPS fp16/bf16."""

    if dtype in (torch.float16, torch.bfloat16):
        return -1.0e4
    return -1.0e9


def _fp32_scaled_dot_product_attention(
    query: torch.Tensor,
    key: torch.Tensor,
    value: torch.Tensor,
    *,
    attn_mask: torch.Tensor | None = None,
) -> torch.Tensor:
    """Run latent-memory attention reductions in FP32, then restore dtype.

    These attention maps are small compared with the frozen decoder, while
    their outputs feed recurrent trajectory and persistent-memory paths.  A
    BF16 reduction error therefore compounds across denoise/commit steps and
    is much more expensive than the modest FP32 workspace.
    """

    output_dtype = query.dtype
    stable_mask = attn_mask
    if stable_mask is not None and stable_mask.is_floating_point():
        stable_mask = stable_mask.float()
    query_fp32 = query.float()
    key_fp32 = key.float()
    use_batched_mm = query.ndim == 4 and key.ndim == 4 and value.ndim == 4
    if use_batched_mm:
        query_length = int(query.shape[-2])
        key_length = int(key.shape[-2])
        scores = torch.bmm(
            query_fp32.reshape(-1, query_length, query.shape[-1]),
            key_fp32.reshape(-1, key_length, key.shape[-1]).transpose(1, 2),
        ).reshape(*query.shape[:-2], query_length, key_length)
    else:
        scores = torch.matmul(query_fp32, key_fp32.transpose(-2, -1))
    scores = scores / math.sqrt(max(query.shape[-1], 1))
    if stable_mask is not None:
        if stable_mask.dtype == torch.bool:
            scores = scores.masked_fill(~stable_mask, _sdpa_mask_value(torch.float32))
        else:
            scores = scores + stable_mask
    probabilities = torch.softmax(scores, dim=-1)
    # All-masked rows are uniform under a finite mask, but keep a NaN
    # barrier for any remaining -inf path that MPS softmax cannot invert.
    probabilities = torch.nan_to_num(probabilities, nan=0.0)
    if use_batched_mm:
        output = torch.bmm(
            probabilities.reshape(-1, query.shape[-2], key.shape[-2]),
            value.float().reshape(-1, key.shape[-2], value.shape[-1]),
        ).reshape(*query.shape[:-2], query.shape[-2], value.shape[-1])
    else:
        output = torch.matmul(probabilities, value.float())
    return output.to(dtype=output_dtype)


@dataclass
class LatentDeliberationState:
    """Persistent slots plus per-canvas trajectory clocks. No token latents."""
    memory_slots: torch.Tensor
    confidence: torch.Tensor
    entropy: torch.Tensor
    ponder_steps: torch.Tensor
    stagnation_steps: torch.Tensor
    gdn2: GDN2TrajectoryState

    @classmethod
    def empty(
        cls,
        *,
        batch_size: int,
        canvas_length: int,
        device: torch.device,
    ) -> "LatentDeliberationState":
        persistent = torch.zeros(batch_size, 16, 128, 128, device=device, dtype=torch.float32)
        return cls(
            memory_slots=persistent,
            confidence=torch.zeros(
                batch_size, canvas_length, device=device, dtype=torch.float32
            ),
            entropy=torch.zeros(
                batch_size, canvas_length, device=device, dtype=torch.float32
            ),
            ponder_steps=torch.zeros(batch_size, device=device, dtype=torch.int32),
            stagnation_steps=torch.zeros(batch_size, device=device, dtype=torch.int32),
            gdn2=GDN2TrajectoryState(
                cells=torch.zeros(batch_size, canvas_length, 16, 64, 64,
                                  device=device, dtype=torch.float32),
                row=torch.zeros(batch_size, 16, 64, 64,
                                device=device, dtype=torch.float32),
                persistent=persistent,
                seen=torch.zeros(batch_size, canvas_length,
                                 device=device, dtype=torch.bool),
            ),
        )


@dataclass
class LatentProcessorOutput:
    context: torch.Tensor
    state: LatentDeliberationState


def advance_trajectory_clocks(
    ponder_steps: torch.Tensor,
    stagnation_steps: torch.Tensor,
    *,
    commit_lengths: torch.LongTensor,
    active_rows: torch.BoolTensor,
) -> tuple[torch.IntTensor, torch.IntTensor]:
    """Advance useful-ponder and stagnation clocks for each row."""

    if not (
        ponder_steps.shape == stagnation_steps.shape == commit_lengths.shape
        == active_rows.shape
    ):
        raise ValueError("Trajectory clock inputs must share shape [batch].")
    committed = commit_lengths.gt(0)
    waiting = active_rows & ~committed
    next_ponder = torch.where(
        committed, torch.zeros_like(ponder_steps), ponder_steps + waiting.to(torch.int32)
    )
    next_stagnation = torch.where(
        committed,
        torch.zeros_like(stagnation_steps),
        stagnation_steps + waiting.to(torch.int32),
    )
    return next_ponder.to(torch.int32), next_stagnation.to(torch.int32)


def should_force_trajectory_jump(
    stagnation_steps: torch.Tensor,
    *,
    progress_scores: torch.Tensor | None = None,
    min_progress: float = 0.0,
    stagnation_threshold: int,
    ponder_steps: torch.Tensor | None = None,
    max_ponder_steps: int | None = None,
) -> torch.BoolTensor:
    jump = stagnation_steps.ge(stagnation_threshold)
    if progress_scores is not None:
        jump = jump & progress_scores.le(float(min_progress))
    if ponder_steps is not None and max_ponder_steps is not None and max_ponder_steps > 0:
        jump = jump | ponder_steps.ge(max_ponder_steps)
    return jump.to(torch.bool)


class _RMSNorm(nn.Module):
    def __init__(self, dim: int, eps: float = 1.0e-6) -> None:
        super().__init__()
        self.weight = nn.Parameter(torch.ones(dim))
        self.eps = eps

    def forward(self, hidden: torch.Tensor) -> torch.Tensor:
        rms = hidden.float().square().mean(dim=-1, keepdim=True).add(self.eps).rsqrt()
        return (hidden.float() * rms * self.weight.float()).to(dtype=hidden.dtype)


class _SwiGLU(nn.Module):
    def __init__(self, dim: int, hidden: int) -> None:
        super().__init__()
        self.gate = nn.Linear(dim, hidden, bias=False)
        self.up = nn.Linear(dim, hidden, bias=False)
        self.down = nn.Linear(hidden, dim, bias=False)

    def forward(self, hidden: torch.Tensor) -> torch.Tensor:
        return self.down(F.silu(self.gate(hidden)) * self.up(hidden))


class _RankAttention(nn.Module):
    """Sequence attention in a rank-``kv_rank`` subspace, then map back to ``dim``."""

    def __init__(self, dim: int, num_heads: int, kv_rank: int) -> None:
        super().__init__()
        if kv_rank % num_heads:
            raise ValueError("`kv_rank` must be divisible by `num_heads`.")
        self.num_heads = num_heads
        self.kv_rank = kv_rank
        self.head_dim = kv_rank // num_heads
        self.q_proj = nn.Linear(dim, kv_rank, bias=False)
        self.k_proj = nn.Linear(dim, kv_rank, bias=False)
        self.v_proj = nn.Linear(dim, kv_rank, bias=False)
        self.o_proj = nn.Linear(kv_rank, dim, bias=False)
        self.q_norm = _RMSNorm(dim)
        self.k_norm = _RMSNorm(dim)

    def forward(
        self,
        query: torch.Tensor,
        keys: torch.Tensor,
        values: torch.Tensor,
        attn_mask: torch.Tensor | None = None,
    ) -> torch.Tensor:
        batch, queries, _dim = query.shape
        key_len = keys.shape[1]
        heads = self.num_heads
        head_dim = self.head_dim
        query = self.q_proj(self.q_norm(query)).view(batch, queries, heads, head_dim).transpose(1, 2)
        keys = self.k_proj(self.k_norm(keys)).view(batch, key_len, heads, head_dim).transpose(1, 2)
        values = self.v_proj(values).view(batch, key_len, heads, head_dim).transpose(1, 2)
        mask = attn_mask
        if mask is not None and mask.ndim == 2:
            mask = mask.view(1, 1, queries, key_len)
        elif mask is not None and mask.ndim == 3:
            mask = mask.unsqueeze(1)
        context = _fp32_scaled_dot_product_attention(
            query, keys, values, attn_mask=mask
        )
        context = context.transpose(1, 2).reshape(batch, queries, self.kv_rank)
        return self.o_proj(context)


class DecoderMemoryBus(nn.Module):
    """Read memory through a per-head gated residual."""

    def __init__(
        self,
        hidden_size: int,
        num_heads: int,
        num_readers: int,
        memory_dim: int,
        kv_rank: int,
        *,
        relative_bias: bool = False,
        address_with_identity: bool = False,
        max_relative_span: int = 256,
    ) -> None:
        super().__init__()
        if num_readers > 0:
            if kv_rank % num_heads:
                raise ValueError("Memory bus rank must be divisible by heads.")
            if hidden_size % num_heads:
                raise ValueError("Memory bus hidden size must be divisible by heads.")
        self.hidden_size = hidden_size
        self.num_heads = num_heads
        self.num_readers = num_readers
        self.kv_rank = kv_rank
        self.head_dim = kv_rank // num_heads if num_heads else kv_rank
        self.relative_bias = relative_bias
        self.address_with_identity = address_with_identity
        self.memory_norm = _RMSNorm(memory_dim)
        self.address_norm = _RMSNorm(memory_dim)
        self.memory_to_hidden = (
            nn.Identity()
            if memory_dim == hidden_size
            else nn.Linear(memory_dim, hidden_size, bias=False)
        )
        self.k_proj = nn.Linear(hidden_size, kv_rank, bias=False)
        self.v_proj = nn.Linear(hidden_size, kv_rank, bias=False)
        self.q_norm = _RMSNorm(hidden_size)
        self.q_proj = nn.ModuleList(
            [nn.Linear(hidden_size, kv_rank, bias=False) for _ in range(num_readers)]
        )
        self.o_proj = nn.ModuleList(
            [nn.Linear(kv_rank, hidden_size, bias=False) for _ in range(num_readers)]
        )
        self.alpha = nn.Parameter(torch.zeros(max(num_readers, 1), max(num_heads, 1)))
        span = max(2 * max_relative_span - 1, 1)
        self.rel_bias = nn.Parameter(torch.zeros(max(num_heads, 1), span))
        self.max_relative_span = max_relative_span


    def prepare_kv(
        self,
        memory: torch.Tensor,
        slot_identity: torch.Tensor | None = None,
    ) -> tuple[torch.Tensor, torch.Tensor] | None:
        if self.num_readers <= 0:
            return None
        if self.address_with_identity:
            if slot_identity is None:
                raise ValueError("Persistent bus requires slot identity on keys.")
            mapped_keys = self.memory_to_hidden(self.address_norm(memory + slot_identity))
            mapped_values = self.memory_to_hidden(self.memory_norm(memory))
        else:
            mapped_keys = mapped_values = self.memory_to_hidden(self.memory_norm(memory))
        batch, slots, _dim = mapped_keys.shape
        heads = self.num_heads
        head_dim = self.head_dim
        keys = self.k_proj(mapped_keys).view(batch, slots, heads, head_dim).transpose(1, 2)
        values = self.v_proj(mapped_values).view(batch, slots, heads, head_dim).transpose(1, 2)
        return keys, values

    def _relative_mask(
        self,
        queries: int,
        keys: int,
        device: torch.device,
        dtype: torch.dtype,
        positions: torch.Tensor | None = None,
    ) -> torch.Tensor | None:
        if not self.relative_bias:
            return None
        if positions is not None:
            if positions.shape[1] != queries or queries != keys:
                raise ValueError("Working memory positions must match both canvas axes.")
            relative = (
                positions[:, :, None] - positions[:, None, :] + (keys - 1)
            ).clamp(0, self.rel_bias.shape[1] - 1)
            return self.rel_bias[:, relative].permute(1, 0, 2, 3).to(dtype=dtype)
        q = torch.arange(queries, device=device)
        k = torch.arange(keys, device=device)
        rel = (q[:, None] - k[None, :] + (keys - 1)).clamp(0, self.rel_bias.shape[1] - 1)
        return self.rel_bias[:, rel].to(dtype=dtype)

    def read(
        self,
        hidden: torch.Tensor,
        reader_index: int,
        keys: torch.Tensor,
        values: torch.Tensor,
        positions: torch.Tensor | None = None,
        *, key_seen: torch.Tensor | None = None,
    ) -> torch.Tensor:
        batch, canvas, _dim = hidden.shape
        heads = self.num_heads
        head_dim = self.head_dim
        query = self.q_proj[reader_index](self.q_norm(hidden))
        query = query.view(batch, canvas, heads, head_dim).transpose(1, 2)
        bias = self._relative_mask(
            canvas, keys.shape[2], hidden.device, query.dtype, positions
        )
        if bias is not None and bias.ndim == 3:
            bias = bias.unsqueeze(0)
        if key_seen is not None:
            key_mask = torch.zeros((batch, 1, 1, keys.shape[2]), device=hidden.device, dtype=torch.float32)
            key_mask = key_mask.masked_fill(~key_seen[:, None, None, :], -1e9)
            bias = key_mask if bias is None else bias.float() + key_mask
        context = _fp32_scaled_dot_product_attention(
            query, keys, values, attn_mask=bias
        )
        if key_seen is not None:
            context = torch.where(key_seen.any(-1)[:, None, None, None], context, torch.zeros_like(context))
        scale = torch.tanh(self.alpha[reader_index]).to(dtype=hidden.dtype).view(1, heads, 1, 1)
        context = context * scale
        context = context.transpose(1, 2).reshape(batch, canvas, self.kv_rank)
        return hidden + self.o_proj[reader_index](context)

    @torch.no_grad()
    def reset_identity_parameters(self) -> None:
        self.alpha.zero_()
        self.rel_bias.zero_()


def slice_latent_state(
    state: LatentDeliberationState, rows: slice | torch.Tensor
) -> LatentDeliberationState:
    return LatentDeliberationState(
        memory_slots=state.memory_slots[rows],
        confidence=state.confidence[rows],
        entropy=state.entropy[rows],
        ponder_steps=state.ponder_steps[rows],
        stagnation_steps=state.stagnation_steps[rows],
        gdn2=GDN2TrajectoryState(
            cells=state.gdn2.cells[rows], row=state.gdn2.row[rows],
            persistent=state.gdn2.persistent[rows], seen=state.gdn2.seen[rows],
        ),
    )


def cat_latent_states(states: Sequence[LatentDeliberationState]) -> LatentDeliberationState:
    def cat(name: str) -> torch.Tensor:
        return torch.cat([getattr(state, name) for state in states], dim=0)

    return LatentDeliberationState(
        memory_slots=cat("memory_slots"),
        confidence=cat("confidence"),
        entropy=cat("entropy"),
        ponder_steps=cat("ponder_steps"),
        stagnation_steps=cat("stagnation_steps"),
        gdn2=GDN2TrajectoryState(
            cells=torch.cat([state.gdn2.cells for state in states], dim=0),
            row=torch.cat([state.gdn2.row for state in states], dim=0),
            persistent=torch.cat([state.gdn2.persistent for state in states], dim=0),
            seen=torch.cat([state.gdn2.seen for state in states], dim=0),
        ),
    )


def infer_commit_reason(
    commit_lengths: torch.Tensor,
    *,
    jump_rows: torch.Tensor | None = None,
    commit_token_ids: torch.Tensor | None = None,
    terminal_token_ids: Sequence[int] = (),
) -> torch.Tensor:
    """Return per-row commit-reason codes. No hard skip; writer sees the label."""

    reasons = torch.full(
        commit_lengths.shape,
        COMMIT_REASON_NONE,
        device=commit_lengths.device,
        dtype=torch.long,
    )
    committed = commit_lengths.gt(0)
    default = (
        COMMIT_REASON_NORMAL
    )
    reasons = torch.where(committed, torch.full_like(reasons, default), reasons)
    if jump_rows is not None:
        reasons = torch.where(
            committed & jump_rows.to(dtype=torch.bool),
            torch.full_like(reasons, COMMIT_REASON_FORCED_JUMP),
            reasons,
        )
    if commit_token_ids is not None and terminal_token_ids:
        positions = torch.arange(
            commit_token_ids.shape[1], device=commit_token_ids.device
        )[None, :]
        selected = positions.lt(commit_lengths[:, None])
        terminal = torch.zeros_like(committed)
        for token_id in terminal_token_ids:
            terminal |= (commit_token_ids.eq(int(token_id)) & selected).any(dim=-1)
        reasons = torch.where(
            committed & terminal,
            torch.full_like(reasons, COMMIT_REASON_TERMINAL),
            reasons,
        )
    return reasons


class _CanvasBlock(nn.Module):
    def __init__(self, width: int, heads: int, rank: int, ffn: int,
                 window: int, global_attention: bool) -> None:
        super().__init__()
        self.norm = _RMSNorm(width)
        self.attn = _RankAttention(width, heads, rank)
        self.ff_norm = _RMSNorm(width)
        self.ff = _SwiGLU(width, ffn)
        self.window = window
        self.global_attention = global_attention

    def forward(self, hidden: torch.Tensor, seen: torch.Tensor,
                offsets: torch.Tensor) -> torch.Tensor:
        allowed = seen[:, None, :].expand(-1, hidden.shape[1], -1)
        if not self.global_attention:
            allowed = allowed & ((offsets[:, :, None] - offsets[:, None, :]).abs() < self.window)
        additive = torch.zeros(allowed.shape, device=hidden.device, dtype=torch.float32)
        additive = additive.masked_fill(~allowed, -1e9)
        normed = self.norm(hidden)
        hidden = hidden + self.attn(normed, normed, normed, attn_mask=additive)
        hidden = hidden + self.ff(self.ff_norm(hidden))
        return torch.where(seen[..., None], hidden, torch.zeros_like(hidden))


class _WorkingBus(DecoderMemoryBus):
    def prepare_kv(self, memory: tuple[torch.Tensor, torch.Tensor],
                   slot_identity: torch.Tensor | None = None):
        del slot_identity
        working, seen = memory
        pair = super().prepare_kv(working)
        return None if pair is None else (*pair, seen)

    def read(self, hidden: torch.Tensor, reader_index: int,
             keys: torch.Tensor, values: torch.Tensor, seen: torch.Tensor,
             positions: torch.Tensor | None = None) -> torch.Tensor:
        written = super().read(hidden, reader_index, keys, values, positions, key_seen=seen)
        return torch.where(seen[..., None], written, hidden)


class _PersistentBus(nn.Module):
    def __init__(self, memory: nn.Module, readers: int) -> None:
        super().__init__()
        object.__setattr__(self, "_memory_ref", weakref.ref(memory))
        self.num_readers = readers
        self.alpha = nn.Parameter(torch.zeros(max(readers, 1), 1))


    def reset_identity_parameters(self) -> None:
        with torch.no_grad():
            self.alpha.zero_()

    def prepare_kv(self, memory: torch.Tensor,
                   seen: torch.Tensor | None = None):
        if self.num_readers <= 0:
            return None
        return memory, seen

    def read(self, hidden: torch.Tensor, reader_index: int,
             memory: torch.Tensor, seen: torch.Tensor | None) -> torch.Tensor:
        delta = self._memory_ref().read_shared(memory, hidden)
        if seen is not None:
            delta = delta * seen[..., None].to(delta.dtype)
        return hidden + torch.tanh(self.alpha[reader_index]).to(hidden.dtype) * delta


class LatentDeliberationTransformer(nn.Module):
    def __init__(self, *, hidden_size: int,
                 latent_dim: int = 2816, ffn_dim: int = 7168,
                  num_layers: int = 4,
                 num_heads: int = 16, local_attention_window: int = 128,
                  tape_probes: int = 4,

                 history_kv_rank: int = 1024, num_memory_readers: int = 0,
                 num_working_readers: int | None = None,
                 num_persistent_readers: int | None = None,
                 working_last_block_global: bool = True,
                 commit_sequence_dim: int | None = None,
                 max_canvas_length: int = 256) -> None:
        super().__init__()
        if hidden_size != latent_dim:
            raise ValueError("Schema25 GDN2 requires hidden_size == latent_dim.")
        self.hidden_size = hidden_size
        self.latent_dim = latent_dim
        self.tape_probes = tape_probes
        self.packet_dim = int(commit_sequence_dim or history_kv_rank)
        if self.packet_dim % num_heads:
            raise ValueError("Commit packet rank must be divisible by attention heads.")
        self.trajectory = GDN2TrajectoryMemory(
            hidden_size, probes=tape_probes, persistent_observation_dim=self.packet_dim,
        )
        self.blocks = nn.ModuleList([
            _CanvasBlock(hidden_size, num_heads, history_kv_rank, ffn_dim,
                         local_attention_window,
                         bool(working_last_block_global and i == num_layers - 1))
            for i in range(num_layers)
        ])
        self.output_norm = _RMSNorm(hidden_size)
        readers = num_memory_readers if num_working_readers is None else num_working_readers
        persistent_readers = (
            num_memory_readers if num_persistent_readers is None else num_persistent_readers
        )
        bus_rank = history_kv_rank if history_kv_rank % num_heads == 0 else num_heads
        self.working_memory_bus = _WorkingBus(
            hidden_size, num_heads, readers, hidden_size, bus_rank,
            relative_bias=True, max_relative_span=max_canvas_length,
        )
        self.persistent_memory_bus = _PersistentBus(
            self.trajectory.persistent, persistent_readers,
        )
        self.experience_in = nn.Linear(hidden_size * 3, self.packet_dim, bias=False)
        self.reason_embed = nn.Embedding(6, self.packet_dim)

    def reset_identity_parameters(self) -> None:
        self.working_memory_bus.reset_identity_parameters()
        self.persistent_memory_bus.reset_identity_parameters()


    def forward(self, *, token_embeddings: torch.Tensor, confidence: torch.Tensor,
                entropy: torch.Tensor, state: LatentDeliberationState,
                canvas_head: torch.Tensor | None = None) -> LatentProcessorOutput:
        batch, canvas, width = token_embeddings.shape
        if state.memory_slots.shape != state.gdn2.persistent.shape:
            raise ValueError("Persistent GDN2 state shape differs from memory slots.")
        memory = replace(state.gdn2, persistent=state.memory_slots)
        hidden = self.trajectory.read(memory, token_embeddings)
        offsets = torch.arange(canvas, device=token_embeddings.device)[None, :].expand(batch, -1)
        if canvas_head is not None:
            offsets = (offsets - canvas_head[:, None]) % canvas
        for block in self.blocks:
            hidden = block(hidden, memory.seen, offsets)
        hidden = self.output_norm(hidden) * memory.seen[..., None].to(hidden.dtype)
        next_state = replace(state, confidence=confidence.float(), entropy=entropy.float(),
                             gdn2=memory)
        return LatentProcessorOutput(hidden, next_state)

    def observe_state(self, state: LatentDeliberationState,
                      heavy: torch.Tensor, working: torch.Tensor,
                      live: torch.Tensor, head: torch.Tensor) -> LatentDeliberationState:
        source = heavy.detach() + working
        updated = self.trajectory.observe(state.gdn2, source, live, head)
        return replace(state, gdn2=updated)


    def commit_write(self, *, memory: torch.Tensor, working_state: torch.Tensor,
                     heavy_hidden: torch.Tensor,
                     committed_token_embeddings: torch.Tensor,
                     commit_lengths: torch.Tensor,
                     commit_reason: torch.Tensor | None = None,
                     canvas_head: torch.Tensor | None = None):
        batch, canvas, width = working_state.shape
        count = int(commit_lengths.max().item())
        if count <= 0:
            return memory
        index = torch.arange(count, device=working_state.device)[None, :].expand(batch, -1)
        if canvas_head is not None:
            index = (index + canvas_head[:, None]) % canvas
        selected_working = working_state.gather(
            1, index[..., None].expand(-1, -1, width)
        )
        selected_heavy = heavy_hidden.detach().gather(
            1, index[..., None].expand(-1, -1, width)
        )
        if committed_token_embeddings.shape != selected_working.shape:
            raise ValueError("Committed embeddings do not match the prefix.")
        # Canvas processing already supplies bidirectional spatial context.
        # Separate normalized role channels feed the ordered GDN2 writer directly.
        # Unit-floor normalization keeps a zero Working state at zero without
        # amplifying its derivative by 1/sqrt(eps) on the first denoise.
        roles = tuple(F.rms_norm(value.float(), (width,), eps=1.0).to(value.dtype)
                      for value in (selected_heavy, selected_working,
                                    committed_token_embeddings.detach()))
        packet = self.experience_in(torch.cat(roles, dim=-1))
        reason = torch.zeros(batch, device=packet.device, dtype=torch.long) if commit_reason is None else commit_reason.long()
        reason = torch.where((reason == 1) | (reason == 2), 5, reason).clamp(0, 5)
        packet = packet + self.reason_embed(reason)[:, None]
        valid = torch.arange(count, device=packet.device)[None, :] < commit_lengths[:, None]
        written = self.trajectory.persistent.write_sequence(memory, packet, valid)
        return written