[System] You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.

[User]
Explain what this code does and identify the inference stage it belongs to.

File: ds4.c

```c
(uint64_t)t * q_dim,
                                        DS4_N_HEAD,
                                        DS4_N_HEAD_DIM,
                                        DS4_N_ROT,
                                        pos0 + t,
                                        il,
                                        true);
            }
        }
        if (profile) t_tl_inv_rope += now_sec() - tx;
    }
    if (profile) t_token_loop = now_sec() - t0;

    t0 = profile ? now_sec() : 0.0;
    layer_grouped_out_batch(attn_out, model, layer, heads, n_tok);
    cpu_directional_steering_project_rows(attn_out, steering_dirs, il, n_tok, steering_scale);

    hc_post_batch(after_attn_hc,
                  attn_out,
                  attn_residual,
                  post,
                  comb,
                  n_tok,
                  DS4_N_EMBD,
                  n_hc);
    if (profile) t_out = now_sec() - t0;

    if (profile) {
        fprintf(stderr,
                "ds4: prefill detail layer %u attn hc_norm=%.3f q=%.3f kv=%.3f token_loop=%.3f out=%.3f total=%.3f\n",
                il, t_hc_norm, t_q, t_kv, t_token_loop, t_out, now_sec() - t_start);
        if (getenv("DS4_PREFILL_PROFILE_TOKEN") != NULL) {
            fprintf(stderr,
                    "ds4: prefill token detail layer %u rope_cache=%.3f compress=%.3f indexer=%.3f attn_rows=%.3f inv_rope=%.3f\n",
                    il, t_tl_rope_cache, t_tl_compress, t_tl_indexer, t_tl_attn_rows, t_tl_inv_rope);
        }
    }

    free(allowed_bits);
    free(allowed_mask);
    free(comp_counts);
    free(index_comp_scratch);
    free(comp_scratch);
    free(comb);
    free(post);
    free(attn_out);
    free(heads);
    free(kv);
    free(kv_raw);
    free(q);
    free(qr_norm);
    free(qr);
    free(attn_residual);
    free(attn_norm);
    free(attn_cur);
}

/* Full transformer layer for one decode token: attention sublayer followed by
 * FFN sublayer, both operating on the HC state. */
static void layer_forward_raw_swa_one(
        float                   * out_hc,
        const ds4_model         * model,
        const ds4_layer_weights * layer,
        ds4_layer_cache         * cache,
        const float             * inp_hc,
        uint32_t                  il,
        uint32_t                  pos,
        int                       token,
        const float             * steering_dirs,
        float                     steering_attn_scale,
        float                     steering_ffn_scale,
        ds4_cpu_decode_scratch  * scratch) {
    const uint32_t n_hc = DS4_N_HC;
```

<｜begin▁of▁sentence｜>You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.<｜User｜>Explain what this code does and identify the inference stage it belongs to.

File: ds4.c

```c
(uint64_t)t * q_dim,
                                        DS4_N_HEAD,
                                        DS4_N_HEAD_DIM,
                                        DS4_N_ROT,
                                        pos0 + t,
                                        il,
                                        true);
            }
        }
        if (profile) t_tl_inv_rope += now_sec() - tx;
    }
    if (profile) t_token_loop = now_sec() - t0;

    t0 = profile ? now_sec() : 0.0;
    layer_grouped_out_batch(attn_out, model, layer, heads, n_tok);
    cpu_directional_steering_project_rows(attn_out, steering_dirs, il, n_tok, steering_scale);

    hc_post_batch(after_attn_hc,
                  attn_out,
                  attn_residual,
                  post,
                  comb,
                  n_tok,
                  DS4_N_EMBD,
                  n_hc);
    if (profile) t_out = now_sec() - t0;

    if (profile) {
        fprintf(stderr,
                "ds4: prefill detail layer %u attn hc_norm=%.3f q=%.3f kv=%.3f token_loop=%.3f out=%.3f total=%.3f\n",
                il, t_hc_norm, t_q, t_kv, t_token_loop, t_out, now_sec() - t_start);
        if (getenv("DS4_PREFILL_PROFILE_TOKEN") != NULL) {
            fprintf(stderr,
                    "ds4: prefill token detail layer %u rope_cache=%.3f compress=%.3f indexer=%.3f attn_rows=%.3f inv_rope=%.3f\n",
                    il, t_tl_rope_cache, t_tl_compress, t_tl_indexer, t_tl_attn_rows, t_tl_inv_rope);
        }
    }

    free(allowed_bits);
    free(allowed_mask);
    free(comp_counts);
    free(index_comp_scratch);
    free(comp_scratch);
    free(comb);
    free(post);
    free(attn_out);
    free(heads);
    free(kv);
    free(kv_raw);
    free(q);
    free(qr_norm);
    free(qr);
    free(attn_residual);
    free(attn_norm);
    free(attn_cur);
}

/* Full transformer layer for one decode token: attention sublayer followed by
 * FFN sublayer, both operating on the HC state. */
static void layer_forward_raw_swa_one(
        float                   * out_hc,
        const ds4_model         * model,
        const ds4_layer_weights * layer,
        ds4_layer_cache         * cache,
        const float             * inp_hc,
        uint32_t                  il,
        uint32_t                  pos,
        int                       token,
        const float             * steering_dirs,
        float                     steering_attn_scale,
        float                     steering_ffn_scale,
        ds4_cpu_decode_scratch  * scratch) {
    const uint32_t n_hc = DS4_N_HC;
```<｜Assistant｜></think>


[System] You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.

[User]
Explain what this code does and identify the inference stage it belongs to.

File: ds4.c

```c
(uint64_t)t * q_dim,
                                        DS4_N_HEAD,
                                        DS4_N_HEAD_DIM,
                                        DS4_N_ROT,
                                        pos0 + t,
                                        il,
                                        true);
            }
        }
        if (profile) t_tl_inv_rope += now_sec() - tx;
    }
    if (profile) t_token_loop = now_sec() - t0;

    t0 = profile ? now_sec() : 0.0;
    layer_grouped_out_batch(attn_out, model, layer, heads, n_tok);
    cpu_directional_steering_project_rows(attn_out, steering_dirs, il, n_tok, steering_scale);

    hc_post_batch(after_attn_hc,
                  attn_out,
                  attn_residual,
                  post,
                  comb,
                  n_tok,
                  DS4_N_EMBD,
                  n_hc);
    if (profile) t_out = now_sec() - t0;

    if (profile) {
        fprintf(stderr,
                "ds4: prefill detail layer %u attn hc_norm=%.3f q=%.3f kv=%.3f token_loop=%.3f out=%.3f total=%.3f\n",
                il, t_hc_norm, t_q, t_kv, t_token_loop, t_out, now_sec() - t_start);
        if (getenv("DS4_PREFILL_PROFILE_TOKEN") != NULL) {
            fprintf(stderr,
                    "ds4: prefill token detail layer %u rope_cache=%.3f compress=%.3f indexer=%.3f attn_rows=%.3f inv_rope=%.3f\n",
                    il, t_tl_rope_cache, t_tl_compress, t_tl_indexer, t_tl_attn_rows, t_tl_inv_rope);
        }
    }

    free(allowed_bits);
    free(allowed_mask);
    free(comp_counts);
    free(index_comp_scratch);
    free(comp_scratch);
    free(comb);
    free(post);
    free(attn_out);
    free(heads);
    free(kv);
    free(kv_raw);
    free(q);
    free(qr_norm);
    free(qr);
    free(attn_residual);
    free(attn_norm);
    free(attn_cur);
}

/* Full transformer layer for one decode token: attention sublayer followed by
 * FFN sublayer, both operating on the HC state. */
static void layer_forward_raw_swa_one(
        float                   * out_hc,
        const ds4_model         * model,
        const ds4_layer_weights * layer,
        ds4_layer_cache         * cache,
        const float             * inp_hc,
        uint32_t                  il,
        uint32_t                  pos,
        int                       token,
        const float             * steering_dirs,
        float                     steering_attn_scale,
        float                     steering_ffn_scale,
        ds4_cpu_decode_scratch  * scratch) {
    const uint32_t n_hc = DS4_N_HC;
```

<｜begin▁of▁sentence｜>You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.<｜User｜>Explain what this code does and identify the inference stage it belongs to.

File: ds4.c

```c
(uint64_t)t * q_dim,
                                        DS4_N_HEAD,
                                        DS4_N_HEAD_DIM,
                                        DS4_N_ROT,
                                        pos0 + t,
                                        il,
                                        true);
            }
        }
        if (profile) t_tl_inv_rope += now_sec() - tx;
    }
    if (profile) t_token_loop = now_sec() - t0;

    t0 = profile ? now_sec() : 0.0;
    layer_grouped_out_batch(attn_out, model, layer, heads, n_tok);
    cpu_directional_steering_project_rows(attn_out, steering_dirs, il, n_tok, steering_scale);

    hc_post_batch(after_attn_hc,
                  attn_out,
                  attn_residual,
                  post,
                  comb,
                  n_tok,
                  DS4_N_EMBD,
                  n_hc);
    if (profile) t_out = now_sec() - t0;

    if (profile) {
        fprintf(stderr,
                "ds4: prefill detail layer %u attn hc_norm=%.3f q=%.3f kv=%.3f token_loop=%.3f out=%.3f total=%.3f\n",
                il, t_hc_norm, t_q, t_kv, t_token_loop, t_out, now_sec() - t_start);
        if (getenv("DS4_PREFILL_PROFILE_TOKEN") != NULL) {
            fprintf(stderr,
                    "ds4: prefill token detail layer %u rope_cache=%.3f compress=%.3f indexer=%.3f attn_rows=%.3f inv_rope=%.3f\n",
                    il, t_tl_rope_cache, t_tl_compress, t_tl_indexer, t_tl_attn_rows, t_tl_inv_rope);
        }
    }

    free(allowed_bits);
    free(allowed_mask);
    free(comp_counts);
    free(index_comp_scratch);
    free(comp_scratch);
    free(comb);
    free(post);
    free(attn_out);
    free(heads);
    free(kv);
    free(kv_raw);
    free(q);
    free(qr_norm);
    free(qr);
    free(attn_residual);
    free(attn_norm);
    free(attn_cur);
}

/* Full transformer layer for one decode token: attention sublayer followed by
 * FFN sublayer, both operating on the HC state. */
static void layer_forward_raw_swa_one(
        float                   * out_hc,
        const ds4_model         * model,
        const ds4_layer_weights * layer,
        ds4_layer_cache         * cache,
        const float             * inp_hc,
        uint32_t                  il,
        uint32_t                  pos,
        int                       token,
        const float             * steering_dirs,
        float                     steering_attn_scale,
        float                     steering_ffn_scale,
        ds4_cpu_decode_scratch  * scratch) {
    const uint32_t n_hc = DS4_N_HC;
```<｜Assistant｜><think>


[System] You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.

[User]
Suggest a minimal correctness-preserving optimization for this excerpt.

File: ds4.c

```c
loat                     steering_attn_scale,
        float                     steering_ffn_scale,
        ds4_cpu_decode_scratch  * scratch) {
    const uint32_t n_hc = DS4_N_HC;
    const bool profile = getenv("DS4_DECODE_PROFILE_DETAIL") != NULL;
    const double t_start = profile ? now_sec() : 0.0;
    double t_hc = 0.0;
    double t_q = 0.0;
    double t_kv = 0.0;
    double t_rope_cache = 0.0;
    double t_compress = 0.0;
    double t_indexer = 0.0;
    double t_attn_rows = 0.0;
    double t_inv_rope = 0.0;
    double t_out = 0.0;
    double t_post = 0.0;
    double t_ffn = 0.0;

    bool *comp_allowed = NULL;
    float post[4];
    float comb[16];

    double t0 = profile ? now_sec() : 0.0;
    memcpy(scratch->attn_residual, inp_hc, (size_t)n_hc * DS4_N_EMBD * sizeof(inp_hc[0]));
    hc_pre_from_state_one_scratch(model,
                                  layer->hc_attn_fn,
                                  layer->hc_attn_scale,
                                  layer->hc_attn_base,
                                  scratch->attn_residual, scratch->attn_cur, post, comb,
                                  scratch->hc_flat,
                                  false);
    if (profile) t_hc = now_sec() - t0;

    t0 = profile ? now_sec() : 0.0;
    layer_attn_norm_one(scratch->attn_norm, model, layer, scratch->attn_cur);
    const uint32_t ratio = cache->compress_ratio;
    layer_q_projection_with_lora_one_decode_scratch(model, layer,
                                                    scratch->attn_norm,
                                                    scratch->q,
                                                    scratch->qr_norm,
                                                    scratch);
    if (profile) t_q = now_sec() - t0;
    t0 = profile ? now_sec() : 0.0;
    layer_kv_projection_normed_one_decode_scratch(model, layer,
                                                  scratch->attn_norm,
                                                  scratch->kv,
                                                  scratch);
    if (profile) t_kv = now_sec() - t0;

    t0 = profile ? now_sec() : 0.0;
    rope_tail_layer_inplace(scratch->q, DS4_N_HEAD, DS4_N_HEAD_DIM, DS4_N_ROT, pos, il, false);
    rope_tail_layer_inplace(scratch->kv, DS4_N_HEAD_KV, DS4_N_HEAD_DIM, DS4_N_ROT, pos, il, false);
    dsv4_fp8_kv_quantize_row_inplace_cpu(scratch->kv, DS4_N_HEAD_DIM, DS4_N_ROT);

    kv_cache_push_raw(cache, scratch->kv);
    if (profile) t_rope_cache = now_sec() - t0;

    if (ratio != 0) {
        t0 = profile ? now_sec() : 0.0;
```

<｜begin▁of▁sentence｜>You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.<｜User｜>Suggest a minimal correctness-preserving optimization for this excerpt.

File: ds4.c

```c
loat                     steering_attn_scale,
        float                     steering_ffn_scale,
        ds4_cpu_decode_scratch  * scratch) {
    const uint32_t n_hc = DS4_N_HC;
    const bool profile = getenv("DS4_DECODE_PROFILE_DETAIL") != NULL;
    const double t_start = profile ? now_sec() : 0.0;
    double t_hc = 0.0;
    double t_q = 0.0;
    double t_kv = 0.0;
    double t_rope_cache = 0.0;
    double t_compress = 0.0;
    double t_indexer = 0.0;
    double t_attn_rows = 0.0;
    double t_inv_rope = 0.0;
    double t_out = 0.0;
    double t_post = 0.0;
    double t_ffn = 0.0;

    bool *comp_allowed = NULL;
    float post[4];
    float comb[16];

    double t0 = profile ? now_sec() : 0.0;
    memcpy(scratch->attn_residual, inp_hc, (size_t)n_hc * DS4_N_EMBD * sizeof(inp_hc[0]));
    hc_pre_from_state_one_scratch(model,
                                  layer->hc_attn_fn,
                                  layer->hc_attn_scale,
                                  layer->hc_attn_base,
                                  scratch->attn_residual, scratch->attn_cur, post, comb,
                                  scratch->hc_flat,
                                  false);
    if (profile) t_hc = now_sec() - t0;

    t0 = profile ? now_sec() : 0.0;
    layer_attn_norm_one(scratch->attn_norm, model, layer, scratch->attn_cur);
    const uint32_t ratio = cache->compress_ratio;
    layer_q_projection_with_lora_one_decode_scratch(model, layer,
                                                    scratch->attn_norm,
                                                    scratch->q,
                                                    scratch->qr_norm,
                                                    scratch);
    if (profile) t_q = now_sec() - t0;
    t0 = profile ? now_sec() : 0.0;
    layer_kv_projection_normed_one_decode_scratch(model, layer,
                                                  scratch->attn_norm,
                                                  scratch->kv,
                                                  scratch);
    if (profile) t_kv = now_sec() - t0;

    t0 = profile ? now_sec() : 0.0;
    rope_tail_layer_inplace(scratch->q, DS4_N_HEAD, DS4_N_HEAD_DIM, DS4_N_ROT, pos, il, false);
    rope_tail_layer_inplace(scratch->kv, DS4_N_HEAD_KV, DS4_N_HEAD_DIM, DS4_N_ROT, pos, il, false);
    dsv4_fp8_kv_quantize_row_inplace_cpu(scratch->kv, DS4_N_HEAD_DIM, DS4_N_ROT);

    kv_cache_push_raw(cache, scratch->kv);
    if (profile) t_rope_cache = now_sec() - t0;

    if (ratio != 0) {
        t0 = profile ? now_sec() : 0.0;
```<｜Assistant｜></think>


[System] You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.

[User]
Suggest a minimal correctness-preserving optimization for this excerpt.

File: ds4.c

```c
loat                     steering_attn_scale,
        float                     steering_ffn_scale,
        ds4_cpu_decode_scratch  * scratch) {
    const uint32_t n_hc = DS4_N_HC;
    const bool profile = getenv("DS4_DECODE_PROFILE_DETAIL") != NULL;
    const double t_start = profile ? now_sec() : 0.0;
    double t_hc = 0.0;
    double t_q = 0.0;
    double t_kv = 0.0;
    double t_rope_cache = 0.0;
    double t_compress = 0.0;
    double t_indexer = 0.0;
    double t_attn_rows = 0.0;
    double t_inv_rope = 0.0;
    double t_out = 0.0;
    double t_post = 0.0;
    double t_ffn = 0.0;

    bool *comp_allowed = NULL;
    float post[4];
    float comb[16];

    double t0 = profile ? now_sec() : 0.0;
    memcpy(scratch->attn_residual, inp_hc, (size_t)n_hc * DS4_N_EMBD * sizeof(inp_hc[0]));
    hc_pre_from_state_one_scratch(model,
                                  layer->hc_attn_fn,
                                  layer->hc_attn_scale,
                                  layer->hc_attn_base,
                                  scratch->attn_residual, scratch->attn_cur, post, comb,
                                  scratch->hc_flat,
                                  false);
    if (profile) t_hc = now_sec() - t0;

    t0 = profile ? now_sec() : 0.0;
    layer_attn_norm_one(scratch->attn_norm, model, layer, scratch->attn_cur);
    const uint32_t ratio = cache->compress_ratio;
    layer_q_projection_with_lora_one_decode_scratch(model, layer,
                                                    scratch->attn_norm,
                                                    scratch->q,
                                                    scratch->qr_norm,
                                                    scratch);
    if (profile) t_q = now_sec() - t0;
    t0 = profile ? now_sec() : 0.0;
    layer_kv_projection_normed_one_decode_scratch(model, layer,
                                                  scratch->attn_norm,
                                                  scratch->kv,
                                                  scratch);
    if (profile) t_kv = now_sec() - t0;

    t0 = profile ? now_sec() : 0.0;
    rope_tail_layer_inplace(scratch->q, DS4_N_HEAD, DS4_N_HEAD_DIM, DS4_N_ROT, pos, il, false);
    rope_tail_layer_inplace(scratch->kv, DS4_N_HEAD_KV, DS4_N_HEAD_DIM, DS4_N_ROT, pos, il, false);
    dsv4_fp8_kv_quantize_row_inplace_cpu(scratch->kv, DS4_N_HEAD_DIM, DS4_N_ROT);

    kv_cache_push_raw(cache, scratch->kv);
    if (profile) t_rope_cache = now_sec() - t0;

    if (ratio != 0) {
        t0 = profile ? now_sec() : 0.0;
```

<｜begin▁of▁sentence｜>You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.<｜User｜>Suggest a minimal correctness-preserving optimization for this excerpt.

File: ds4.c

```c
loat                     steering_attn_scale,
        float                     steering_ffn_scale,
        ds4_cpu_decode_scratch  * scratch) {
    const uint32_t n_hc = DS4_N_HC;
    const bool profile = getenv("DS4_DECODE_PROFILE_DETAIL") != NULL;
    const double t_start = profile ? now_sec() : 0.0;
    double t_hc = 0.0;
    double t_q = 0.0;
    double t_kv = 0.0;
    double t_rope_cache = 0.0;
    double t_compress = 0.0;
    double t_indexer = 0.0;
    double t_attn_rows = 0.0;
    double t_inv_rope = 0.0;
    double t_out = 0.0;
    double t_post = 0.0;
    double t_ffn = 0.0;

    bool *comp_allowed = NULL;
    float post[4];
    float comb[16];

    double t0 = profile ? now_sec() : 0.0;
    memcpy(scratch->attn_residual, inp_hc, (size_t)n_hc * DS4_N_EMBD * sizeof(inp_hc[0]));
    hc_pre_from_state_one_scratch(model,
                                  layer->hc_attn_fn,
                                  layer->hc_attn_scale,
                                  layer->hc_attn_base,
                                  scratch->attn_residual, scratch->attn_cur, post, comb,
                                  scratch->hc_flat,
                                  false);
    if (profile) t_hc = now_sec() - t0;

    t0 = profile ? now_sec() : 0.0;
    layer_attn_norm_one(scratch->attn_norm, model, layer, scratch->attn_cur);
    const uint32_t ratio = cache->compress_ratio;
    layer_q_projection_with_lora_one_decode_scratch(model, layer,
                                                    scratch->attn_norm,
                                                    scratch->q,
                                                    scratch->qr_norm,
                                                    scratch);
    if (profile) t_q = now_sec() - t0;
    t0 = profile ? now_sec() : 0.0;
    layer_kv_projection_normed_one_decode_scratch(model, layer,
                                                  scratch->attn_norm,
                                                  scratch->kv,
                                                  scratch);
    if (profile) t_kv = now_sec() - t0;

    t0 = profile ? now_sec() : 0.0;
    rope_tail_layer_inplace(scratch->q, DS4_N_HEAD, DS4_N_HEAD_DIM, DS4_N_ROT, pos, il, false);
    rope_tail_layer_inplace(scratch->kv, DS4_N_HEAD_KV, DS4_N_HEAD_DIM, DS4_N_ROT, pos, il, false);
    dsv4_fp8_kv_quantize_row_inplace_cpu(scratch->kv, DS4_N_HEAD_DIM, DS4_N_ROT);

    kv_cache_push_raw(cache, scratch->kv);
    if (profile) t_rope_cache = now_sec() - t0;

    if (ratio != 0) {
        t0 = profile ? now_sec() : 0.0;
```<｜Assistant｜><think>


[System] You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.

[User]
Trova bug sottili e spiega quali invarianti dell'inferenza possono rompersi.

File: ds4.c

```c
4_N_HEAD_DIM, DS4_N_ROT);

    kv_cache_push_raw(cache, scratch->kv);
    if (profile) t_rope_cache = now_sec() - t0;

    if (ratio != 0) {
        t0 = profile ? now_sec() : 0.0;
        if (compressor_decode_one_decode_scratch(scratch->comp, model,
                                                 layer->attn_compressor_kv,
                                                 layer->attn_compressor_gate,
                                                 layer->attn_compressor_ape,
                                                 layer->attn_compressor_norm,
                                                 scratch->attn_norm,
                                                 cache->attn_state_kv,
                                                 cache->attn_state_score,
                                                 DS4_N_HEAD_DIM,
                                                 ratio,
                                                 il,
                                                 pos,
                                                 scratch)) {
            kv_cache_push_comp(cache->attn_comp_kv, &cache->n_comp, cache->comp_cap, DS4_N_HEAD_DIM, scratch->comp);
        }

        if (ratio == 4) {
            if (compressor_decode_one_decode_scratch(scratch->index_comp, model,
                                                     layer->indexer_compressor_kv,
                                                     layer->indexer_compressor_gate,
                                                     layer->indexer_compressor_ape,
                                                     layer->indexer_compressor_norm,
                                                     scratch->attn_norm,
                                                     cache->index_state_kv,
                                                     cache->index_state_score,
                                                     DS4_N_INDEXER_HEAD_DIM,
                                                     ratio,
                                                     il,
                                                     pos,
                                                     scratch)) {
                kv_cache_push_comp(cache->index_comp_kv, &cache->n_index_comp, cache->comp_cap,
                                   DS4_N_INDEXER_HEAD_DIM, scratch->index_comp);
            }
            if (profile) t_compress = now_sec() - t0;
        } else if (profile) {
            t_compress = now_sec() - t0;
        }
    }
    if (ratio == 4) {
        t0 = profile ? now_sec() : 0.0;
```

<｜begin▁of▁sentence｜>You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.<｜User｜>Trova bug sottili e spiega quali invarianti dell'inferenza possono rompersi.

File: ds4.c

```c
4_N_HEAD_DIM, DS4_N_ROT);

    kv_cache_push_raw(cache, scratch->kv);
    if (profile) t_rope_cache = now_sec() - t0;

    if (ratio != 0) {
        t0 = profile ? now_sec() : 0.0;
        if (compressor_decode_one_decode_scratch(scratch->comp, model,
                                                 layer->attn_compressor_kv,
                                                 layer->attn_compressor_gate,
                                                 layer->attn_compressor_ape,
                                                 layer->attn_compressor_norm,
                                                 scratch->attn_norm,
                                                 cache->attn_state_kv,
                                                 cache->attn_state_score,
                                                 DS4_N_HEAD_DIM,
                                                 ratio,
                                                 il,
                                                 pos,
                                                 scratch)) {
            kv_cache_push_comp(cache->attn_comp_kv, &cache->n_comp, cache->comp_cap, DS4_N_HEAD_DIM, scratch->comp);
        }

        if (ratio == 4) {
            if (compressor_decode_one_decode_scratch(scratch->index_comp, model,
                                                     layer->indexer_compressor_kv,
                                                     layer->indexer_compressor_gate,
                                                     layer->indexer_compressor_ape,
                                                     layer->indexer_compressor_norm,
                                                     scratch->attn_norm,
                                                     cache->index_state_kv,
                                                     cache->index_state_score,
                                                     DS4_N_INDEXER_HEAD_DIM,
                                                     ratio,
                                                     il,
                                                     pos,
                                                     scratch)) {
                kv_cache_push_comp(cache->index_comp_kv, &cache->n_index_comp, cache->comp_cap,
                                   DS4_N_INDEXER_HEAD_DIM, scratch->index_comp);
            }
            if (profile) t_compress = now_sec() - t0;
        } else if (profile) {
            t_compress = now_sec() - t0;
        }
    }
    if (ratio == 4) {
        t0 = profile ? now_sec() : 0.0;
```<｜Assistant｜></think>


[System] You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.

[User]
Trova bug sottili e spiega quali invarianti dell'inferenza possono rompersi.

File: ds4.c

```c
4_N_HEAD_DIM, DS4_N_ROT);

    kv_cache_push_raw(cache, scratch->kv);
    if (profile) t_rope_cache = now_sec() - t0;

    if (ratio != 0) {
        t0 = profile ? now_sec() : 0.0;
        if (compressor_decode_one_decode_scratch(scratch->comp, model,
                                                 layer->attn_compressor_kv,
                                                 layer->attn_compressor_gate,
                                                 layer->attn_compressor_ape,
                                                 layer->attn_compressor_norm,
                                                 scratch->attn_norm,
                                                 cache->attn_state_kv,
                                                 cache->attn_state_score,
                                                 DS4_N_HEAD_DIM,
                                                 ratio,
                                                 il,
                                                 pos,
                                                 scratch)) {
            kv_cache_push_comp(cache->attn_comp_kv, &cache->n_comp, cache->comp_cap, DS4_N_HEAD_DIM, scratch->comp);
        }

        if (ratio == 4) {
            if (compressor_decode_one_decode_scratch(scratch->index_comp, model,
                                                     layer->indexer_compressor_kv,
                                                     layer->indexer_compressor_gate,
                                                     layer->indexer_compressor_ape,
                                                     layer->indexer_compressor_norm,
                                                     scratch->attn_norm,
                                                     cache->index_state_kv,
                                                     cache->index_state_score,
                                                     DS4_N_INDEXER_HEAD_DIM,
                                                     ratio,
                                                     il,
                                                     pos,
                                                     scratch)) {
                kv_cache_push_comp(cache->index_comp_kv, &cache->n_index_comp, cache->comp_cap,
                                   DS4_N_INDEXER_HEAD_DIM, scratch->index_comp);
            }
            if (profile) t_compress = now_sec() - t0;
        } else if (profile) {
            t_compress = now_sec() - t0;
        }
    }
    if (ratio == 4) {
        t0 = profile ? now_sec() : 0.0;
```

<｜begin▁of▁sentence｜>You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.<｜User｜>Trova bug sottili e spiega quali invarianti dell'inferenza possono rompersi.

File: ds4.c

```c
4_N_HEAD_DIM, DS4_N_ROT);

    kv_cache_push_raw(cache, scratch->kv);
    if (profile) t_rope_cache = now_sec() - t0;

    if (ratio != 0) {
        t0 = profile ? now_sec() : 0.0;
        if (compressor_decode_one_decode_scratch(scratch->comp, model,
                                                 layer->attn_compressor_kv,
                                                 layer->attn_compressor_gate,
                                                 layer->attn_compressor_ape,
                                                 layer->attn_compressor_norm,
                                                 scratch->attn_norm,
                                                 cache->attn_state_kv,
                                                 cache->attn_state_score,
                                                 DS4_N_HEAD_DIM,
                                                 ratio,
                                                 il,
                                                 pos,
                                                 scratch)) {
            kv_cache_push_comp(cache->attn_comp_kv, &cache->n_comp, cache->comp_cap, DS4_N_HEAD_DIM, scratch->comp);
        }

        if (ratio == 4) {
            if (compressor_decode_one_decode_scratch(scratch->index_comp, model,
                                                     layer->indexer_compressor_kv,
                                                     layer->indexer_compressor_gate,
                                                     layer->indexer_compressor_ape,
                                                     layer->indexer_compressor_norm,
                                                     scratch->attn_norm,
                                                     cache->index_state_kv,
                                                     cache->index_state_score,
                                                     DS4_N_INDEXER_HEAD_DIM,
                                                     ratio,
                                                     il,
                                                     pos,
                                                     scratch)) {
                kv_cache_push_comp(cache->index_comp_kv, &cache->n_index_comp, cache->comp_cap,
                                   DS4_N_INDEXER_HEAD_DIM, scratch->index_comp);
            }
            if (profile) t_compress = now_sec() - t0;
        } else if (profile) {
            t_compress = now_sec() - t0;
        }
    }
    if (ratio == 4) {
        t0 = profile ? now_sec() : 0.0;
```<｜Assistant｜><think>


[System] You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.

[User]
Review this excerpt for correctness risks, memory lifetime issues, and performance bottlenecks.

File: ds4.c

```c
e) t_compress = now_sec() - t0;
        } else if (profile) {
            t_compress = now_sec() - t0;
        }
    }
    if (ratio == 4) {
        t0 = profile ? now_sec() : 0.0;
        comp_allowed = indexer_allowed_decode_one_decode_scratch(model, layer,
                                                                 scratch->attn_norm,
                                                                 scratch->qr_norm,
                                                                 cache->index_comp_kv,
                                                                 cache->n_index_comp,
                                                                 il, pos,
                                                                 scratch);
        if (profile) t_indexer = now_sec() - t0;
    }

    t0 = profile ? now_sec() : 0.0;
    if (ratio != 0) {
        layer_attention_mixed_one_decode_scratch(scratch->heads, model, layer, scratch->q,
                                                 cache->raw_kv, cache->n_raw,
                                                 cache->attn_comp_kv, cache->n_comp,
                                                 comp_allowed,
                                                 scratch);
    } else {
        layer_attention_rows_one(scratch->heads, model, layer, scratch->q, cache->raw_kv, cache->n_raw);
    }
    if (profile) t_attn_rows = now_sec() - t0;

    t0 = profile ? now_sec() : 0.0;
    rope_tail_layer_inplace(scratch->heads, DS4_N_HEAD, DS4_N_HEAD_DIM, DS4_N_ROT, pos, il, true);
    if (profile) t_inv_rope = now_sec() - t0;
    t0 = profile ? now_sec() : 0.0;
    layer_grouped_out_one_decode_scratch(scratch->attn_out, model, layer, scratch->heads, scratch);
    cpu_directional_steering_project_rows(scratch->attn_out, steering_dirs, il, 1, steering_attn_scale);
    if (profile) t_out = now_sec() - t0;
    t0 = profile ? now_sec() : 0.0;
    hc_post_one(scratch->after_attn_hc, scratch->attn_out, scratch->attn_residual, post, comb, DS4_N_EMBD, n_hc);
    if (profile) t_post = now_sec() - t0;

    t0 = profile ? now_sec() : 0.0;
    layer_ffn_one_decode_scratch(out_hc, model, layer, scratch->after_attn_hc, il, token,
                                 steering_dirs, steering_ffn_scale, scratch);
    if (profile) t_ffn = now_sec() - t0;

    if (profile) {
        fprintf(stderr,
                "ds4: decode detail layer %u attn hc=%.3f q=%.3f kv=%.3f rope=%.3f compress=%.3f indexer=%.3f attn_rows=%.3f inv_rope=%.3f out=%.3f post=%.3f ffn=%.3f total=%.3f ms\n",
                il,
                t_hc * 1000.0,
```

<｜begin▁of▁sentence｜>You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.<｜User｜>Review this excerpt for correctness risks, memory lifetime issues, and performance bottlenecks.

File: ds4.c

```c
e) t_compress = now_sec() - t0;
        } else if (profile) {
            t_compress = now_sec() - t0;
        }
    }
    if (ratio == 4) {
        t0 = profile ? now_sec() : 0.0;
        comp_allowed = indexer_allowed_decode_one_decode_scratch(model, layer,
                                                                 scratch->attn_norm,
                                                                 scratch->qr_norm,
                                                                 cache->index_comp_kv,
                                                                 cache->n_index_comp,
                                                                 il, pos,
                                                                 scratch);
        if (profile) t_indexer = now_sec() - t0;
    }

    t0 = profile ? now_sec() : 0.0;
    if (ratio != 0) {
        layer_attention_mixed_one_decode_scratch(scratch->heads, model, layer, scratch->q,
                                                 cache->raw_kv, cache->n_raw,
                                                 cache->attn_comp_kv, cache->n_comp,
                                                 comp_allowed,
                                                 scratch);
    } else {
        layer_attention_rows_one(scratch->heads, model, layer, scratch->q, cache->raw_kv, cache->n_raw);
    }
    if (profile) t_attn_rows = now_sec() - t0;

    t0 = profile ? now_sec() : 0.0;
    rope_tail_layer_inplace(scratch->heads, DS4_N_HEAD, DS4_N_HEAD_DIM, DS4_N_ROT, pos, il, true);
    if (profile) t_inv_rope = now_sec() - t0;
    t0 = profile ? now_sec() : 0.0;
    layer_grouped_out_one_decode_scratch(scratch->attn_out, model, layer, scratch->heads, scratch);
    cpu_directional_steering_project_rows(scratch->attn_out, steering_dirs, il, 1, steering_attn_scale);
    if (profile) t_out = now_sec() - t0;
    t0 = profile ? now_sec() : 0.0;
    hc_post_one(scratch->after_attn_hc, scratch->attn_out, scratch->attn_residual, post, comb, DS4_N_EMBD, n_hc);
    if (profile) t_post = now_sec() - t0;

    t0 = profile ? now_sec() : 0.0;
    layer_ffn_one_decode_scratch(out_hc, model, layer, scratch->after_attn_hc, il, token,
                                 steering_dirs, steering_ffn_scale, scratch);
    if (profile) t_ffn = now_sec() - t0;

    if (profile) {
        fprintf(stderr,
                "ds4: decode detail layer %u attn hc=%.3f q=%.3f kv=%.3f rope=%.3f compress=%.3f indexer=%.3f attn_rows=%.3f inv_rope=%.3f out=%.3f post=%.3f ffn=%.3f total=%.3f ms\n",
                il,
                t_hc * 1000.0,
```<｜Assistant｜></think>


[System] You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.

[User]
Review this excerpt for correctness risks, memory lifetime issues, and performance bottlenecks.

File: ds4.c

```c
e) t_compress = now_sec() - t0;
        } else if (profile) {
            t_compress = now_sec() - t0;
        }
    }
    if (ratio == 4) {
        t0 = profile ? now_sec() : 0.0;
        comp_allowed = indexer_allowed_decode_one_decode_scratch(model, layer,
                                                                 scratch->attn_norm,
                                                                 scratch->qr_norm,
                                                                 cache->index_comp_kv,
                                                                 cache->n_index_comp,
                                                                 il, pos,
                                                                 scratch);
        if (profile) t_indexer = now_sec() - t0;
    }

    t0 = profile ? now_sec() : 0.0;
    if (ratio != 0) {
        layer_attention_mixed_one_decode_scratch(scratch->heads, model, layer, scratch->q,
                                                 cache->raw_kv, cache->n_raw,
                                                 cache->attn_comp_kv, cache->n_comp,
                                                 comp_allowed,
                                                 scratch);
    } else {
        layer_attention_rows_one(scratch->heads, model, layer, scratch->q, cache->raw_kv, cache->n_raw);
    }
    if (profile) t_attn_rows = now_sec() - t0;

    t0 = profile ? now_sec() : 0.0;
    rope_tail_layer_inplace(scratch->heads, DS4_N_HEAD, DS4_N_HEAD_DIM, DS4_N_ROT, pos, il, true);
    if (profile) t_inv_rope = now_sec() - t0;
    t0 = profile ? now_sec() : 0.0;
    layer_grouped_out_one_decode_scratch(scratch->attn_out, model, layer, scratch->heads, scratch);
    cpu_directional_steering_project_rows(scratch->attn_out, steering_dirs, il, 1, steering_attn_scale);
    if (profile) t_out = now_sec() - t0;
    t0 = profile ? now_sec() : 0.0;
    hc_post_one(scratch->after_attn_hc, scratch->attn_out, scratch->attn_residual, post, comb, DS4_N_EMBD, n_hc);
    if (profile) t_post = now_sec() - t0;

    t0 = profile ? now_sec() : 0.0;
    layer_ffn_one_decode_scratch(out_hc, model, layer, scratch->after_attn_hc, il, token,
                                 steering_dirs, steering_ffn_scale, scratch);
    if (profile) t_ffn = now_sec() - t0;

    if (profile) {
        fprintf(stderr,
                "ds4: decode detail layer %u attn hc=%.3f q=%.3f kv=%.3f rope=%.3f compress=%.3f indexer=%.3f attn_rows=%.3f inv_rope=%.3f out=%.3f post=%.3f ffn=%.3f total=%.3f ms\n",
                il,
                t_hc * 1000.0,
```

<｜begin▁of▁sentence｜>You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.<｜User｜>Review this excerpt for correctness risks, memory lifetime issues, and performance bottlenecks.

File: ds4.c

```c
e) t_compress = now_sec() - t0;
        } else if (profile) {
            t_compress = now_sec() - t0;
        }
    }
    if (ratio == 4) {
        t0 = profile ? now_sec() : 0.0;
        comp_allowed = indexer_allowed_decode_one_decode_scratch(model, layer,
                                                                 scratch->attn_norm,
                                                                 scratch->qr_norm,
                                                                 cache->index_comp_kv,
                                                                 cache->n_index_comp,
                                                                 il, pos,
                                                                 scratch);
        if (profile) t_indexer = now_sec() - t0;
    }

    t0 = profile ? now_sec() : 0.0;
    if (ratio != 0) {
        layer_attention_mixed_one_decode_scratch(scratch->heads, model, layer, scratch->q,
                                                 cache->raw_kv, cache->n_raw,
                                                 cache->attn_comp_kv, cache->n_comp,
                                                 comp_allowed,
                                                 scratch);
    } else {
        layer_attention_rows_one(scratch->heads, model, layer, scratch->q, cache->raw_kv, cache->n_raw);
    }
    if (profile) t_attn_rows = now_sec() - t0;

    t0 = profile ? now_sec() : 0.0;
    rope_tail_layer_inplace(scratch->heads, DS4_N_HEAD, DS4_N_HEAD_DIM, DS4_N_ROT, pos, il, true);
    if (profile) t_inv_rope = now_sec() - t0;
    t0 = profile ? now_sec() : 0.0;
    layer_grouped_out_one_decode_scratch(scratch->attn_out, model, layer, scratch->heads, scratch);
    cpu_directional_steering_project_rows(scratch->attn_out, steering_dirs, il, 1, steering_attn_scale);
    if (profile) t_out = now_sec() - t0;
    t0 = profile ? now_sec() : 0.0;
    hc_post_one(scratch->after_attn_hc, scratch->attn_out, scratch->attn_residual, post, comb, DS4_N_EMBD, n_hc);
    if (profile) t_post = now_sec() - t0;

    t0 = profile ? now_sec() : 0.0;
    layer_ffn_one_decode_scratch(out_hc, model, layer, scratch->after_attn_hc, il, token,
                                 steering_dirs, steering_ffn_scale, scratch);
    if (profile) t_ffn = now_sec() - t0;

    if (profile) {
        fprintf(stderr,
                "ds4: decode detail layer %u attn hc=%.3f q=%.3f kv=%.3f rope=%.3f compress=%.3f indexer=%.3f attn_rows=%.3f inv_rope=%.3f out=%.3f post=%.3f ffn=%.3f total=%.3f ms\n",
                il,
                t_hc * 1000.0,
```<｜Assistant｜><think>


[System] You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.

[User]
Explain what this code does and identify the inference stage it belongs to.

File: ds4.c

```c
3f q=%.3f kv=%.3f rope=%.3f compress=%.3f indexer=%.3f attn_rows=%.3f inv_rope=%.3f out=%.3f post=%.3f ffn=%.3f total=%.3f ms\n",
                il,
                t_hc * 1000.0,
                t_q * 1000.0,
                t_kv * 1000.0,
                t_rope_cache * 1000.0,
                t_compress * 1000.0,
                t_indexer * 1000.0,
                t_attn_rows * 1000.0,
                t_inv_rope * 1000.0,
                t_out * 1000.0,
                t_post * 1000.0,
                t_ffn * 1000.0,
                (now_sec() - t_start) * 1000.0);
    }

}

static void output_logits_one_decode_scratch(
        float                  * logits,
        const ds4_model        * model,
        const ds4_weights      * weights,
        const float            * inp_hc,
        ds4_cpu_decode_scratch * scratch);

/* CPU decode for one token through all 43 layers.  The caller owns scratch and
 * cache lifetimes so no per-token allocations are needed. */
static void forward_token_raw_swa_cpu_decode_scratch(
        float             * logits,
        const ds4_model   * model,
        const ds4_weights * weights,
        ds4_kv_cache      * cache,
        int                 token,
        uint32_t            pos,
        const float       * steering_dirs,
        float               steering_attn_scale,
        float               steering_ffn_scale,
        ds4_cpu_decode_scratch * scratch) {
    float *cur = scratch->cur;
    float *next = scratch->next;

    embed_token_f16(model, weights, token, scratch->plain);
    hc_from_plain_embedding(cur, scratch->plain, DS4_N_EMBD, DS4_N_HC);

    for (uint32_t il = 0; il < DS4_N_LAYER; il++) {
        layer_forward_raw_swa_one(next, model, &weights->layer[il], &cache->layer[il],
                                  cur, il, pos, token,
                                  steering_dirs,
                                  steering_attn_scale,
                                  steering_ffn_scale,
                                  scratch);
        float *tmp = cur;
        cur = next;
        next = tmp;
    }

    if (logits) {
        output_logits_one_decode_scratch(logits, model, weights, cur, scratch);
    }
}

#ifndef DS4_NO_GPU
static void forward_token_raw_swa_cpu(
        float             * logits,
        const ds4_model   * model,
        const ds4_weights * weights,
        ds4_kv_cache      * cache,
        int                 token,
        uint32_t            pos) {
    ds4_cpu_decode_scratch scratch;
    uint32_t ctx_guess = pos + 1;
    for (uint32_t il = 0; il < DS4_N_LAYER; il++) {
```

<｜begin▁of▁sentence｜>You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.<｜User｜>Explain what this code does and identify the inference stage it belongs to.

File: ds4.c

```c
3f q=%.3f kv=%.3f rope=%.3f compress=%.3f indexer=%.3f attn_rows=%.3f inv_rope=%.3f out=%.3f post=%.3f ffn=%.3f total=%.3f ms\n",
                il,
                t_hc * 1000.0,
                t_q * 1000.0,
                t_kv * 1000.0,
                t_rope_cache * 1000.0,
                t_compress * 1000.0,
                t_indexer * 1000.0,
                t_attn_rows * 1000.0,
                t_inv_rope * 1000.0,
                t_out * 1000.0,
                t_post * 1000.0,
                t_ffn * 1000.0,
                (now_sec() - t_start) * 1000.0);
    }

}

static void output_logits_one_decode_scratch(
        float                  * logits,
        const ds4_model        * model,
        const ds4_weights      * weights,
        const float            * inp_hc,
        ds4_cpu_decode_scratch * scratch);

/* CPU decode for one token through all 43 layers.  The caller owns scratch and
 * cache lifetimes so no per-token allocations are needed. */
static void forward_token_raw_swa_cpu_decode_scratch(
        float             * logits,
        const ds4_model   * model,
        const ds4_weights * weights,
        ds4_kv_cache      * cache,
        int                 token,
        uint32_t            pos,
        const float       * steering_dirs,
        float               steering_attn_scale,
        float               steering_ffn_scale,
        ds4_cpu_decode_scratch * scratch) {
    float *cur = scratch->cur;
    float *next = scratch->next;

    embed_token_f16(model, weights, token, scratch->plain);
    hc_from_plain_embedding(cur, scratch->plain, DS4_N_EMBD, DS4_N_HC);

    for (uint32_t il = 0; il < DS4_N_LAYER; il++) {
        layer_forward_raw_swa_one(next, model, &weights->layer[il], &cache->layer[il],
                                  cur, il, pos, token,
                                  steering_dirs,
                                  steering_attn_scale,
                                  steering_ffn_scale,
                                  scratch);
        float *tmp = cur;
        cur = next;
        next = tmp;
    }

    if (logits) {
        output_logits_one_decode_scratch(logits, model, weights, cur, scratch);
    }
}

#ifndef DS4_NO_GPU
static void forward_token_raw_swa_cpu(
        float             * logits,
        const ds4_model   * model,
        const ds4_weights * weights,
        ds4_kv_cache      * cache,
        int                 token,
        uint32_t            pos) {
    ds4_cpu_decode_scratch scratch;
    uint32_t ctx_guess = pos + 1;
    for (uint32_t il = 0; il < DS4_N_LAYER; il++) {
```<｜Assistant｜></think>


[System] You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.

[User]
Explain what this code does and identify the inference stage it belongs to.

File: ds4.c

```c
3f q=%.3f kv=%.3f rope=%.3f compress=%.3f indexer=%.3f attn_rows=%.3f inv_rope=%.3f out=%.3f post=%.3f ffn=%.3f total=%.3f ms\n",
                il,
                t_hc * 1000.0,
                t_q * 1000.0,
                t_kv * 1000.0,
                t_rope_cache * 1000.0,
                t_compress * 1000.0,
                t_indexer * 1000.0,
                t_attn_rows * 1000.0,
                t_inv_rope * 1000.0,
                t_out * 1000.0,
                t_post * 1000.0,
                t_ffn * 1000.0,
                (now_sec() - t_start) * 1000.0);
    }

}

static void output_logits_one_decode_scratch(
        float                  * logits,
        const ds4_model        * model,
        const ds4_weights      * weights,
        const float            * inp_hc,
        ds4_cpu_decode_scratch * scratch);

/* CPU decode for one token through all 43 layers.  The caller owns scratch and
 * cache lifetimes so no per-token allocations are needed. */
static void forward_token_raw_swa_cpu_decode_scratch(
        float             * logits,
        const ds4_model   * model,
        const ds4_weights * weights,
        ds4_kv_cache      * cache,
        int                 token,
        uint32_t            pos,
        const float       * steering_dirs,
        float               steering_attn_scale,
        float               steering_ffn_scale,
        ds4_cpu_decode_scratch * scratch) {
    float *cur = scratch->cur;
    float *next = scratch->next;

    embed_token_f16(model, weights, token, scratch->plain);
    hc_from_plain_embedding(cur, scratch->plain, DS4_N_EMBD, DS4_N_HC);

    for (uint32_t il = 0; il < DS4_N_LAYER; il++) {
        layer_forward_raw_swa_one(next, model, &weights->layer[il], &cache->layer[il],
                                  cur, il, pos, token,
                                  steering_dirs,
                                  steering_attn_scale,
                                  steering_ffn_scale,
                                  scratch);
        float *tmp = cur;
        cur = next;
        next = tmp;
    }

    if (logits) {
        output_logits_one_decode_scratch(logits, model, weights, cur, scratch);
    }
}

#ifndef DS4_NO_GPU
static void forward_token_raw_swa_cpu(
        float             * logits,
        const ds4_model   * model,
        const ds4_weights * weights,
        ds4_kv_cache      * cache,
        int                 token,
        uint32_t            pos) {
    ds4_cpu_decode_scratch scratch;
    uint32_t ctx_guess = pos + 1;
    for (uint32_t il = 0; il < DS4_N_LAYER; il++) {
```

<｜begin▁of▁sentence｜>You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.<｜User｜>Explain what this code does and identify the inference stage it belongs to.

File: ds4.c

```c
3f q=%.3f kv=%.3f rope=%.3f compress=%.3f indexer=%.3f attn_rows=%.3f inv_rope=%.3f out=%.3f post=%.3f ffn=%.3f total=%.3f ms\n",
                il,
                t_hc * 1000.0,
                t_q * 1000.0,
                t_kv * 1000.0,
                t_rope_cache * 1000.0,
                t_compress * 1000.0,
                t_indexer * 1000.0,
                t_attn_rows * 1000.0,
                t_inv_rope * 1000.0,
                t_out * 1000.0,
                t_post * 1000.0,
                t_ffn * 1000.0,
                (now_sec() - t_start) * 1000.0);
    }

}

static void output_logits_one_decode_scratch(
        float                  * logits,
        const ds4_model        * model,
        const ds4_weights      * weights,
        const float            * inp_hc,
        ds4_cpu_decode_scratch * scratch);

/* CPU decode for one token through all 43 layers.  The caller owns scratch and
 * cache lifetimes so no per-token allocations are needed. */
static void forward_token_raw_swa_cpu_decode_scratch(
        float             * logits,
        const ds4_model   * model,
        const ds4_weights * weights,
        ds4_kv_cache      * cache,
        int                 token,
        uint32_t            pos,
        const float       * steering_dirs,
        float               steering_attn_scale,
        float               steering_ffn_scale,
        ds4_cpu_decode_scratch * scratch) {
    float *cur = scratch->cur;
    float *next = scratch->next;

    embed_token_f16(model, weights, token, scratch->plain);
    hc_from_plain_embedding(cur, scratch->plain, DS4_N_EMBD, DS4_N_HC);

    for (uint32_t il = 0; il < DS4_N_LAYER; il++) {
        layer_forward_raw_swa_one(next, model, &weights->layer[il], &cache->layer[il],
                                  cur, il, pos, token,
                                  steering_dirs,
                                  steering_attn_scale,
                                  steering_ffn_scale,
                                  scratch);
        float *tmp = cur;
        cur = next;
        next = tmp;
    }

    if (logits) {
        output_logits_one_decode_scratch(logits, model, weights, cur, scratch);
    }
}

#ifndef DS4_NO_GPU
static void forward_token_raw_swa_cpu(
        float             * logits,
        const ds4_model   * model,
        const ds4_weights * weights,
        ds4_kv_cache      * cache,
        int                 token,
        uint32_t            pos) {
    ds4_cpu_decode_scratch scratch;
    uint32_t ctx_guess = pos + 1;
    for (uint32_t il = 0; il < DS4_N_LAYER; il++) {
```<｜Assistant｜><think>


[System] You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.

[User]
Suggest a minimal correctness-preserving optimization for this excerpt.

File: ds4.c

```c
token,
        uint32_t            pos) {
    ds4_cpu_decode_scratch scratch;
    uint32_t ctx_guess = pos + 1;
    for (uint32_t il = 0; il < DS4_N_LAYER; il++) {
        const uint32_t ratio = cache->layer[il].compress_ratio;
        if (ratio != 0 && cache->layer[il].comp_cap > 2) {
            const uint32_t ctx_from_comp = (cache->layer[il].comp_cap - 2u) * ratio;
            if (ctx_guess < ctx_from_comp) ctx_guess = ctx_from_comp;
        }
    }
    cpu_decode_scratch_init(&scratch, ctx_guess);
    forward_token_raw_swa_cpu_decode_scratch(logits, model, weights, cache, token, pos,
                                             NULL, 0.0f, 0.0f, &scratch);
    cpu_decode_scratch_free(&scratch);
}
#endif

/* CPU prefill in layer-major order.  All prompt tokens pass through layer 0,
 * then layer 1, etc., which exposes batch matmul opportunities. */
static void prefill_layer_major_cpu(
        float             * logits,
        const ds4_model   * model,
        const ds4_weights * weights,
        ds4_kv_cache      * cache,
        const token_vec   * prompt,
        const float       * steering_dirs,
        float               steering_attn_scale,
        float               steering_ffn_scale) {
    const uint64_t hc_dim = (uint64_t)DS4_N_HC * DS4_N_EMBD;
    const uint64_t n_tok = (uint64_t)prompt->len;
    float *cur = xmalloc((size_t)n_tok * hc_dim * sizeof(cur[0]));
    float *next = xmalloc((size_t)n_tok * hc_dim * sizeof(next[0]));
    float *attn = xmalloc((size_t)n_tok * hc_dim * sizeof(attn[0]));
    float *plain = xmalloc((size_t)DS4_N_EMBD * sizeof(plain[0]));
    uint32_t ffn_batch = 128;
    const bool batched_attn = getenv("DS4_NO_BATCHED_ATTN") == NULL;
    const bool batched_ffn = getenv("DS4_BATCHED_FFN") != NULL;
    const bool parallel_ffn = getenv("DS4_PARALLEL_FFN") != NULL;
    const bool shared_batch_ffn = getenv("DS4_NO_SHARED_BATCH_FFN") == NULL;
    const char *batch_env = getenv("DS4_PREFILL_BATCH");
    ds4_cpu_decode_scratch decode_scratch;
    bool decode_scratch_ready = false;
    if (batch_env && batch_env[0]) {
        long v = strtol(batch_env, NULL, 10);
        if (v > 0 && v < 4096) ffn_batch = (uint32_t)v;
    }

    for (uint64_t t = 0; t < n_tok; t++) {
        embed_token_f16(model, weights, prompt->v[t], plain);
        hc_from_plain_embedding(cur + t * hc_dim, plain, DS4_N_EMBD, DS4_N_HC);
    }

    free(plain);

    for (uint32_t il = 0; il < DS4_N_LAYER; il++) {
        fprintf(stderr, "ds4: prefill layer %u/%u\r", il + 1, (uint32_t)DS4_N_LAYER);
        fflush(stderr);
```

<｜begin▁of▁sentence｜>You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.<｜User｜>Suggest a minimal correctness-preserving optimization for this excerpt.

File: ds4.c

```c
token,
        uint32_t            pos) {
    ds4_cpu_decode_scratch scratch;
    uint32_t ctx_guess = pos + 1;
    for (uint32_t il = 0; il < DS4_N_LAYER; il++) {
        const uint32_t ratio = cache->layer[il].compress_ratio;
        if (ratio != 0 && cache->layer[il].comp_cap > 2) {
            const uint32_t ctx_from_comp = (cache->layer[il].comp_cap - 2u) * ratio;
            if (ctx_guess < ctx_from_comp) ctx_guess = ctx_from_comp;
        }
    }
    cpu_decode_scratch_init(&scratch, ctx_guess);
    forward_token_raw_swa_cpu_decode_scratch(logits, model, weights, cache, token, pos,
                                             NULL, 0.0f, 0.0f, &scratch);
    cpu_decode_scratch_free(&scratch);
}
#endif

/* CPU prefill in layer-major order.  All prompt tokens pass through layer 0,
 * then layer 1, etc., which exposes batch matmul opportunities. */
static void prefill_layer_major_cpu(
        float             * logits,
        const ds4_model   * model,
        const ds4_weights * weights,
        ds4_kv_cache      * cache,
        const token_vec   * prompt,
        const float       * steering_dirs,
        float               steering_attn_scale,
        float               steering_ffn_scale) {
    const uint64_t hc_dim = (uint64_t)DS4_N_HC * DS4_N_EMBD;
    const uint64_t n_tok = (uint64_t)prompt->len;
    float *cur = xmalloc((size_t)n_tok * hc_dim * sizeof(cur[0]));
    float *next = xmalloc((size_t)n_tok * hc_dim * sizeof(next[0]));
    float *attn = xmalloc((size_t)n_tok * hc_dim * sizeof(attn[0]));
    float *plain = xmalloc((size_t)DS4_N_EMBD * sizeof(plain[0]));
    uint32_t ffn_batch = 128;
    const bool batched_attn = getenv("DS4_NO_BATCHED_ATTN") == NULL;
    const bool batched_ffn = getenv("DS4_BATCHED_FFN") != NULL;
    const bool parallel_ffn = getenv("DS4_PARALLEL_FFN") != NULL;
    const bool shared_batch_ffn = getenv("DS4_NO_SHARED_BATCH_FFN") == NULL;
    const char *batch_env = getenv("DS4_PREFILL_BATCH");
    ds4_cpu_decode_scratch decode_scratch;
    bool decode_scratch_ready = false;
    if (batch_env && batch_env[0]) {
        long v = strtol(batch_env, NULL, 10);
        if (v > 0 && v < 4096) ffn_batch = (uint32_t)v;
    }

    for (uint64_t t = 0; t < n_tok; t++) {
        embed_token_f16(model, weights, prompt->v[t], plain);
        hc_from_plain_embedding(cur + t * hc_dim, plain, DS4_N_EMBD, DS4_N_HC);
    }

    free(plain);

    for (uint32_t il = 0; il < DS4_N_LAYER; il++) {
        fprintf(stderr, "ds4: prefill layer %u/%u\r", il + 1, (uint32_t)DS4_N_LAYER);
        fflush(stderr);
```<｜Assistant｜></think>


[System] You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.

[User]
Suggest a minimal correctness-preserving optimization for this excerpt.

File: ds4.c

```c
token,
        uint32_t            pos) {
    ds4_cpu_decode_scratch scratch;
    uint32_t ctx_guess = pos + 1;
    for (uint32_t il = 0; il < DS4_N_LAYER; il++) {
        const uint32_t ratio = cache->layer[il].compress_ratio;
        if (ratio != 0 && cache->layer[il].comp_cap > 2) {
            const uint32_t ctx_from_comp = (cache->layer[il].comp_cap - 2u) * ratio;
            if (ctx_guess < ctx_from_comp) ctx_guess = ctx_from_comp;
        }
    }
    cpu_decode_scratch_init(&scratch, ctx_guess);
    forward_token_raw_swa_cpu_decode_scratch(logits, model, weights, cache, token, pos,
                                             NULL, 0.0f, 0.0f, &scratch);
    cpu_decode_scratch_free(&scratch);
}
#endif

/* CPU prefill in layer-major order.  All prompt tokens pass through layer 0,
 * then layer 1, etc., which exposes batch matmul opportunities. */
static void prefill_layer_major_cpu(
        float             * logits,
        const ds4_model   * model,
        const ds4_weights * weights,
        ds4_kv_cache      * cache,
        const token_vec   * prompt,
        const float       * steering_dirs,
        float               steering_attn_scale,
        float               steering_ffn_scale) {
    const uint64_t hc_dim = (uint64_t)DS4_N_HC * DS4_N_EMBD;
    const uint64_t n_tok = (uint64_t)prompt->len;
    float *cur = xmalloc((size_t)n_tok * hc_dim * sizeof(cur[0]));
    float *next = xmalloc((size_t)n_tok * hc_dim * sizeof(next[0]));
    float *attn = xmalloc((size_t)n_tok * hc_dim * sizeof(attn[0]));
    float *plain = xmalloc((size_t)DS4_N_EMBD * sizeof(plain[0]));
    uint32_t ffn_batch = 128;
    const bool batched_attn = getenv("DS4_NO_BATCHED_ATTN") == NULL;
    const bool batched_ffn = getenv("DS4_BATCHED_FFN") != NULL;
    const bool parallel_ffn = getenv("DS4_PARALLEL_FFN") != NULL;
    const bool shared_batch_ffn = getenv("DS4_NO_SHARED_BATCH_FFN") == NULL;
    const char *batch_env = getenv("DS4_PREFILL_BATCH");
    ds4_cpu_decode_scratch decode_scratch;
    bool decode_scratch_ready = false;
    if (batch_env && batch_env[0]) {
        long v = strtol(batch_env, NULL, 10);
        if (v > 0 && v < 4096) ffn_batch = (uint32_t)v;
    }

    for (uint64_t t = 0; t < n_tok; t++) {
        embed_token_f16(model, weights, prompt->v[t], plain);
        hc_from_plain_embedding(cur + t * hc_dim, plain, DS4_N_EMBD, DS4_N_HC);
    }

    free(plain);

    for (uint32_t il = 0; il < DS4_N_LAYER; il++) {
        fprintf(stderr, "ds4: prefill layer %u/%u\r", il + 1, (uint32_t)DS4_N_LAYER);
        fflush(stderr);
```

<｜begin▁of▁sentence｜>You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.<｜User｜>Suggest a minimal correctness-preserving optimization for this excerpt.

File: ds4.c

```c
token,
        uint32_t            pos) {
    ds4_cpu_decode_scratch scratch;
    uint32_t ctx_guess = pos + 1;
    for (uint32_t il = 0; il < DS4_N_LAYER; il++) {
        const uint32_t ratio = cache->layer[il].compress_ratio;
        if (ratio != 0 && cache->layer[il].comp_cap > 2) {
            const uint32_t ctx_from_comp = (cache->layer[il].comp_cap - 2u) * ratio;
            if (ctx_guess < ctx_from_comp) ctx_guess = ctx_from_comp;
        }
    }
    cpu_decode_scratch_init(&scratch, ctx_guess);
    forward_token_raw_swa_cpu_decode_scratch(logits, model, weights, cache, token, pos,
                                             NULL, 0.0f, 0.0f, &scratch);
    cpu_decode_scratch_free(&scratch);
}
#endif

/* CPU prefill in layer-major order.  All prompt tokens pass through layer 0,
 * then layer 1, etc., which exposes batch matmul opportunities. */
static void prefill_layer_major_cpu(
        float             * logits,
        const ds4_model   * model,
        const ds4_weights * weights,
        ds4_kv_cache      * cache,
        const token_vec   * prompt,
        const float       * steering_dirs,
        float               steering_attn_scale,
        float               steering_ffn_scale) {
    const uint64_t hc_dim = (uint64_t)DS4_N_HC * DS4_N_EMBD;
    const uint64_t n_tok = (uint64_t)prompt->len;
    float *cur = xmalloc((size_t)n_tok * hc_dim * sizeof(cur[0]));
    float *next = xmalloc((size_t)n_tok * hc_dim * sizeof(next[0]));
    float *attn = xmalloc((size_t)n_tok * hc_dim * sizeof(attn[0]));
    float *plain = xmalloc((size_t)DS4_N_EMBD * sizeof(plain[0]));
    uint32_t ffn_batch = 128;
    const bool batched_attn = getenv("DS4_NO_BATCHED_ATTN") == NULL;
    const bool batched_ffn = getenv("DS4_BATCHED_FFN") != NULL;
    const bool parallel_ffn = getenv("DS4_PARALLEL_FFN") != NULL;
    const bool shared_batch_ffn = getenv("DS4_NO_SHARED_BATCH_FFN") == NULL;
    const char *batch_env = getenv("DS4_PREFILL_BATCH");
    ds4_cpu_decode_scratch decode_scratch;
    bool decode_scratch_ready = false;
    if (batch_env && batch_env[0]) {
        long v = strtol(batch_env, NULL, 10);
        if (v > 0 && v < 4096) ffn_batch = (uint32_t)v;
    }

    for (uint64_t t = 0; t < n_tok; t++) {
        embed_token_f16(model, weights, prompt->v[t], plain);
        hc_from_plain_embedding(cur + t * hc_dim, plain, DS4_N_EMBD, DS4_N_HC);
    }

    free(plain);

    for (uint32_t il = 0; il < DS4_N_LAYER; il++) {
        fprintf(stderr, "ds4: prefill layer %u/%u\r", il + 1, (uint32_t)DS4_N_LAYER);
        fflush(stderr);
```<｜Assistant｜><think>


[System] You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.

[User]
Trova bug sottili e spiega quali invarianti dell'inferenza possono rompersi.

File: ds4.c

```c
free(plain);

    for (uint32_t il = 0; il < DS4_N_LAYER; il++) {
        fprintf(stderr, "ds4: prefill layer %u/%u\r", il + 1, (uint32_t)DS4_N_LAYER);
        fflush(stderr);

        if (batched_attn) {
            layer_attention_raw_swa_batch(attn,
                                          model,
                                          &weights->layer[il],
                                          &cache->layer[il],
                                          cur,
                                          (uint32_t)n_tok,
                                          il,
                                          0,
                                          steering_dirs,
                                          steering_attn_scale);

            if (batched_ffn) {
                for (uint64_t t = 0; t < n_tok; t += ffn_batch) {
                    uint32_t nb = (uint32_t)((n_tok - t) < ffn_batch ? (n_tok - t) : ffn_batch);
                    layer_ffn_batch(next + t * hc_dim,
                                    model,
                                    &weights->layer[il],
                                    attn + t * hc_dim,
                                    prompt->v + t,
                                    nb,
                                    il,
                                    steering_dirs,
                                    steering_ffn_scale);
                }
            } else if (shared_batch_ffn) {
                layer_ffn_shared_batch(next,
                                       model,
                                       &weights->layer[il],
                                       attn,
                                       prompt->v,
                                       (uint32_t)n_tok,
                                       il,
                                       steering_dirs,
                                       steering_ffn_scale);
            } else if (parallel_ffn) {
                layer_ffn_tokens_parallel(next,
                                          model,
                                          &weights->layer[il],
                                          attn,
                                          prompt->v,
                                          (uint32_t)n_tok,
                                          il,
                                          steering_dirs,
                                          steering_ffn_scale);
            } else {
                for (uint64_t t = 0; t < n_tok; t++) {
                    layer_ffn_one(next + t * hc_dim,
```

<｜begin▁of▁sentence｜>You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.<｜User｜>Trova bug sottili e spiega quali invarianti dell'inferenza possono rompersi.

File: ds4.c

```c
free(plain);

    for (uint32_t il = 0; il < DS4_N_LAYER; il++) {
        fprintf(stderr, "ds4: prefill layer %u/%u\r", il + 1, (uint32_t)DS4_N_LAYER);
        fflush(stderr);

        if (batched_attn) {
            layer_attention_raw_swa_batch(attn,
                                          model,
                                          &weights->layer[il],
                                          &cache->layer[il],
                                          cur,
                                          (uint32_t)n_tok,
                                          il,
                                          0,
                                          steering_dirs,
                                          steering_attn_scale);

            if (batched_ffn) {
                for (uint64_t t = 0; t < n_tok; t += ffn_batch) {
                    uint32_t nb = (uint32_t)((n_tok - t) < ffn_batch ? (n_tok - t) : ffn_batch);
                    layer_ffn_batch(next + t * hc_dim,
                                    model,
                                    &weights->layer[il],
                                    attn + t * hc_dim,
                                    prompt->v + t,
                                    nb,
                                    il,
                                    steering_dirs,
                                    steering_ffn_scale);
                }
            } else if (shared_batch_ffn) {
                layer_ffn_shared_batch(next,
                                       model,
                                       &weights->layer[il],
                                       attn,
                                       prompt->v,
                                       (uint32_t)n_tok,
                                       il,
                                       steering_dirs,
                                       steering_ffn_scale);
            } else if (parallel_ffn) {
                layer_ffn_tokens_parallel(next,
                                          model,
                                          &weights->layer[il],
                                          attn,
                                          prompt->v,
                                          (uint32_t)n_tok,
                                          il,
                                          steering_dirs,
                                          steering_ffn_scale);
            } else {
                for (uint64_t t = 0; t < n_tok; t++) {
                    layer_ffn_one(next + t * hc_dim,
```<｜Assistant｜></think>


[System] You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.

[User]
Trova bug sottili e spiega quali invarianti dell'inferenza possono rompersi.

File: ds4.c

```c
free(plain);

    for (uint32_t il = 0; il < DS4_N_LAYER; il++) {
        fprintf(stderr, "ds4: prefill layer %u/%u\r", il + 1, (uint32_t)DS4_N_LAYER);
        fflush(stderr);

        if (batched_attn) {
            layer_attention_raw_swa_batch(attn,
                                          model,
                                          &weights->layer[il],
                                          &cache->layer[il],
                                          cur,
                                          (uint32_t)n_tok,
                                          il,
                                          0,
                                          steering_dirs,
                                          steering_attn_scale);

            if (batched_ffn) {
                for (uint64_t t = 0; t < n_tok; t += ffn_batch) {
                    uint32_t nb = (uint32_t)((n_tok - t) < ffn_batch ? (n_tok - t) : ffn_batch);
                    layer_ffn_batch(next + t * hc_dim,
                                    model,
                                    &weights->layer[il],
                                    attn + t * hc_dim,
                                    prompt->v + t,
                                    nb,
                                    il,
                                    steering_dirs,
                                    steering_ffn_scale);
                }
            } else if (shared_batch_ffn) {
                layer_ffn_shared_batch(next,
                                       model,
                                       &weights->layer[il],
                                       attn,
                                       prompt->v,
                                       (uint32_t)n_tok,
                                       il,
                                       steering_dirs,
                                       steering_ffn_scale);
            } else if (parallel_ffn) {
                layer_ffn_tokens_parallel(next,
                                          model,
                                          &weights->layer[il],
                                          attn,
                                          prompt->v,
                                          (uint32_t)n_tok,
                                          il,
                                          steering_dirs,
                                          steering_ffn_scale);
            } else {
                for (uint64_t t = 0; t < n_tok; t++) {
                    layer_ffn_one(next + t * hc_dim,
```

<｜begin▁of▁sentence｜>You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.<｜User｜>Trova bug sottili e spiega quali invarianti dell'inferenza possono rompersi.

File: ds4.c

```c
free(plain);

    for (uint32_t il = 0; il < DS4_N_LAYER; il++) {
        fprintf(stderr, "ds4: prefill layer %u/%u\r", il + 1, (uint32_t)DS4_N_LAYER);
        fflush(stderr);

        if (batched_attn) {
            layer_attention_raw_swa_batch(attn,
                                          model,
                                          &weights->layer[il],
                                          &cache->layer[il],
                                          cur,
                                          (uint32_t)n_tok,
                                          il,
                                          0,
                                          steering_dirs,
                                          steering_attn_scale);

            if (batched_ffn) {
                for (uint64_t t = 0; t < n_tok; t += ffn_batch) {
                    uint32_t nb = (uint32_t)((n_tok - t) < ffn_batch ? (n_tok - t) : ffn_batch);
                    layer_ffn_batch(next + t * hc_dim,
                                    model,
                                    &weights->layer[il],
                                    attn + t * hc_dim,
                                    prompt->v + t,
                                    nb,
                                    il,
                                    steering_dirs,
                                    steering_ffn_scale);
                }
            } else if (shared_batch_ffn) {
                layer_ffn_shared_batch(next,
                                       model,
                                       &weights->layer[il],
                                       attn,
                                       prompt->v,
                                       (uint32_t)n_tok,
                                       il,
                                       steering_dirs,
                                       steering_ffn_scale);
            } else if (parallel_ffn) {
                layer_ffn_tokens_parallel(next,
                                          model,
                                          &weights->layer[il],
                                          attn,
                                          prompt->v,
                                          (uint32_t)n_tok,
                                          il,
                                          steering_dirs,
                                          steering_ffn_scale);
            } else {
                for (uint64_t t = 0; t < n_tok; t++) {
                    layer_ffn_one(next + t * hc_dim,
```<｜Assistant｜><think>


[System] You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.

[User]
Review this excerpt for correctness risks, memory lifetime issues, and performance bottlenecks.

File: ds4.c

```c
steering_ffn_scale);
            } else {
                for (uint64_t t = 0; t < n_tok; t++) {
                    layer_ffn_one(next + t * hc_dim,
                                  model,
                                  &weights->layer[il],
                                  attn + t * hc_dim,
                                  il,
                                  prompt->v[t],
                                  steering_dirs,
                                  steering_ffn_scale,
                                  false);
                }
            }
        } else if (batched_ffn) {
            for (uint64_t t = 0; t < n_tok; t++) {
                layer_attention_raw_swa_one(attn + t * hc_dim,
                                            model,
                                            &weights->layer[il],
                                            &cache->layer[il],
                                            cur + t * hc_dim,
                                            il,
                                            (uint32_t)t,
                                            steering_dirs,
                                            steering_attn_scale);
            }

            for (uint64_t t = 0; t < n_tok; t += ffn_batch) {
                uint32_t nb = (uint32_t)((n_tok - t) < ffn_batch ? (n_tok - t) : ffn_batch);
                layer_ffn_batch(next + t * hc_dim,
                                model,
                                &weights->layer[il],
                                attn + t * hc_dim,
                                prompt->v + t,
                                nb,
                                il,
                                steering_dirs,
                                steering_ffn_scale);
            }
        } else {
            if (!decode_scratch_ready) {
                cpu_decode_scratch_init(&decode_scratch, (uint32_t)n_tok);
                decode_scratch_ready = true;
            }
            for (uint64_t t = 0; t < n_tok; t++) {
                layer_forward_raw_swa_one(next + t * hc_dim,
                                          model,
                                          &weights->layer[il],
                                          &cache->layer[il],
                                          cur + t * hc_dim,
                                          il,
                                          (uint32_t)t,
                                          prompt->v[t],
                                          steering_dirs,
```

<｜begin▁of▁sentence｜>You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.<｜User｜>Review this excerpt for correctness risks, memory lifetime issues, and performance bottlenecks.

File: ds4.c

```c
steering_ffn_scale);
            } else {
                for (uint64_t t = 0; t < n_tok; t++) {
                    layer_ffn_one(next + t * hc_dim,
                                  model,
                                  &weights->layer[il],
                                  attn + t * hc_dim,
                                  il,
                                  prompt->v[t],
                                  steering_dirs,
                                  steering_ffn_scale,
                                  false);
                }
            }
        } else if (batched_ffn) {
            for (uint64_t t = 0; t < n_tok; t++) {
                layer_attention_raw_swa_one(attn + t * hc_dim,
                                            model,
                                            &weights->layer[il],
                                            &cache->layer[il],
                                            cur + t * hc_dim,
                                            il,
                                            (uint32_t)t,
                                            steering_dirs,
                                            steering_attn_scale);
            }

            for (uint64_t t = 0; t < n_tok; t += ffn_batch) {
                uint32_t nb = (uint32_t)((n_tok - t) < ffn_batch ? (n_tok - t) : ffn_batch);
                layer_ffn_batch(next + t * hc_dim,
                                model,
                                &weights->layer[il],
                                attn + t * hc_dim,
                                prompt->v + t,
                                nb,
                                il,
                                steering_dirs,
                                steering_ffn_scale);
            }
        } else {
            if (!decode_scratch_ready) {
                cpu_decode_scratch_init(&decode_scratch, (uint32_t)n_tok);
                decode_scratch_ready = true;
            }
            for (uint64_t t = 0; t < n_tok; t++) {
                layer_forward_raw_swa_one(next + t * hc_dim,
                                          model,
                                          &weights->layer[il],
                                          &cache->layer[il],
                                          cur + t * hc_dim,
                                          il,
                                          (uint32_t)t,
                                          prompt->v[t],
                                          steering_dirs,
```<｜Assistant｜></think>


[System] You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.

[User]
Review this excerpt for correctness risks, memory lifetime issues, and performance bottlenecks.

File: ds4.c

```c
steering_ffn_scale);
            } else {
                for (uint64_t t = 0; t < n_tok; t++) {
                    layer_ffn_one(next + t * hc_dim,
                                  model,
                                  &weights->layer[il],
                                  attn + t * hc_dim,
                                  il,
                                  prompt->v[t],
                                  steering_dirs,
                                  steering_ffn_scale,
                                  false);
                }
            }
        } else if (batched_ffn) {
            for (uint64_t t = 0; t < n_tok; t++) {
                layer_attention_raw_swa_one(attn + t * hc_dim,
                                            model,
                                            &weights->layer[il],
                                            &cache->layer[il],
                                            cur + t * hc_dim,
                                            il,
                                            (uint32_t)t,
                                            steering_dirs,
                                            steering_attn_scale);
            }

            for (uint64_t t = 0; t < n_tok; t += ffn_batch) {
                uint32_t nb = (uint32_t)((n_tok - t) < ffn_batch ? (n_tok - t) : ffn_batch);
                layer_ffn_batch(next + t * hc_dim,
                                model,
                                &weights->layer[il],
                                attn + t * hc_dim,
                                prompt->v + t,
                                nb,
                                il,
                                steering_dirs,
                                steering_ffn_scale);
            }
        } else {
            if (!decode_scratch_ready) {
                cpu_decode_scratch_init(&decode_scratch, (uint32_t)n_tok);
                decode_scratch_ready = true;
            }
            for (uint64_t t = 0; t < n_tok; t++) {
                layer_forward_raw_swa_one(next + t * hc_dim,
                                          model,
                                          &weights->layer[il],
                                          &cache->layer[il],
                                          cur + t * hc_dim,
                                          il,
                                          (uint32_t)t,
                                          prompt->v[t],
                                          steering_dirs,
```

<｜begin▁of▁sentence｜>You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.<｜User｜>Review this excerpt for correctness risks, memory lifetime issues, and performance bottlenecks.

File: ds4.c

```c
steering_ffn_scale);
            } else {
                for (uint64_t t = 0; t < n_tok; t++) {
                    layer_ffn_one(next + t * hc_dim,
                                  model,
                                  &weights->layer[il],
                                  attn + t * hc_dim,
                                  il,
                                  prompt->v[t],
                                  steering_dirs,
                                  steering_ffn_scale,
                                  false);
                }
            }
        } else if (batched_ffn) {
            for (uint64_t t = 0; t < n_tok; t++) {
                layer_attention_raw_swa_one(attn + t * hc_dim,
                                            model,
                                            &weights->layer[il],
                                            &cache->layer[il],
                                            cur + t * hc_dim,
                                            il,
                                            (uint32_t)t,
                                            steering_dirs,
                                            steering_attn_scale);
            }

            for (uint64_t t = 0; t < n_tok; t += ffn_batch) {
                uint32_t nb = (uint32_t)((n_tok - t) < ffn_batch ? (n_tok - t) : ffn_batch);
                layer_ffn_batch(next + t * hc_dim,
                                model,
                                &weights->layer[il],
                                attn + t * hc_dim,
                                prompt->v + t,
                                nb,
                                il,
                                steering_dirs,
                                steering_ffn_scale);
            }
        } else {
            if (!decode_scratch_ready) {
                cpu_decode_scratch_init(&decode_scratch, (uint32_t)n_tok);
                decode_scratch_ready = true;
            }
            for (uint64_t t = 0; t < n_tok; t++) {
                layer_forward_raw_swa_one(next + t * hc_dim,
                                          model,
                                          &weights->layer[il],
                                          &cache->layer[il],
                                          cur + t * hc_dim,
                                          il,
                                          (uint32_t)t,
                                          prompt->v[t],
                                          steering_dirs,
```<｜Assistant｜><think>


[System] You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.

[User]
Explain what this code does and identify the inference stage it belongs to.

File: ds4.c

```c
il,
                                          (uint32_t)t,
                                          prompt->v[t],
                                          steering_dirs,
                                          steering_attn_scale,
                                          steering_ffn_scale,
                                          &decode_scratch);
            }
        }

        float *tmp = cur;
        cur = next;
        next = tmp;
    }

    kv_cache_finish_prefill_states(cache, (uint32_t)n_tok);

    if (logits) {
        output_logits_one(logits, model, weights, cur + (n_tok - 1) * hc_dim);
    }

    if (decode_scratch_ready) cpu_decode_scratch_free(&decode_scratch);
    free(next);
    free(cur);
    free(attn);
}

/* Diagnostic first-token layer without cache history: the token attends only
 * to itself, useful for checking a minimal end-to-end slice. */
static void layer_forward_self_one(
        float                   * out_hc,
        const ds4_model         * model,
        const ds4_layer_weights * layer,
        const float             * inp_hc,
        uint32_t                  il,
        uint32_t                  pos,
        int                       token) {
    const uint32_t n_hc = DS4_N_HC;
    const uint64_t q_dim = (uint64_t)DS4_N_HEAD * DS4_N_HEAD_DIM;

    float *attn_cur = xmalloc((size_t)DS4_N_EMBD * sizeof(attn_cur[0]));
    float *attn_norm = xmalloc((size_t)DS4_N_EMBD * sizeof(attn_norm[0]));
    float *attn_residual = xmalloc((size_t)n_hc * DS4_N_EMBD * sizeof(attn_residual[0]));
    float *q = xmalloc((size_t)q_dim * sizeof(q[0]));
    float *kv = xmalloc((size_t)DS4_N_HEAD_DIM * sizeof(kv[0]));
    float *heads = xmalloc((size_t)q_dim * sizeof(heads[0]));
    float *attn_out = xmalloc((size_t)DS4_N_EMBD * sizeof(attn_out[0]));
    float *after_attn_hc = xmalloc((size_t)n_hc * DS4_N_EMBD * sizeof(after_attn_hc[0]));
    float post[4];
    float comb[16];

    memcpy(attn_residual, inp_hc, (size_t)n_hc * DS4_N_EMBD * sizeof(inp_hc[0]));
    hc_pre_from_state_one(model,
                          layer->hc_attn_fn,
                          layer->hc_attn_scale,
                          layer->hc_attn_base,
                          attn_residual, attn_cur, post, comb);

    layer_attn_norm_one(attn_norm, model, layer, attn_cur);
    layer_q_projection_normed_one(model, layer, attn_norm, q);
    layer_kv_projection_normed_one(model, layer, attn_norm, kv);
    rope_tail_layer_inplace(q, DS4_N_HEAD, DS4_N_HEAD_DIM, DS4_N_ROT, pos, il, false);
```

<｜begin▁of▁sentence｜>You are DeepSeek V4 Flash running locally. Answer accurately, preserve technical details, and use tools only when the prompt asks for tool use.<｜User｜>Explain what this code does and identify the inference stage it belongs to.

File: ds4.c

```c
il,
                                          (uint32_t)t,
                                          prompt->v[t],
                                          steering_dirs,
                                          steering_attn_scale,
                                          steering_ffn_scale,
                                          &decode_scratch);
            }
        }

        float *tmp = cur;
        cur = next;
        next = tmp;
    }

    kv_cache_finish_prefill_states(cache, (uint32_t)n_tok);

    if (logits) {
        output_logits_one(logits, model, weights, cur + (n_tok - 1) * hc_dim);
    }

    if (decode_scratch_ready) cpu_decode_scratch_free(&decode_scratch);
    free(next);
    free(cur);
    free(attn);
}

/* Diagnostic first-token layer without cache history: the token attends only
 * to itself, useful for checking a minimal end-to-end slice. */
static void layer_forward_self_one(
        float                   * out_hc,
        const ds4_model         * model,
        const ds4_layer_weights * layer,
        const float             * inp_hc,
        uint32_t                  il,
        uint32_t                  pos,
        int                       token) {
    const uint32_t n_hc = DS4_N_HC;
    const uint64_t q_dim = (uint64_t)DS4_N_HEAD * DS4_N_HEAD_DIM;

    float *attn_cur = xmalloc((size_t)DS4_N_EMBD * sizeof(attn_cur[0]));
    float *attn_norm = xmalloc((size_t)DS4_N_EMBD * sizeof(attn_norm[0]));
    float *attn_residual = xmalloc((size_t)n_hc * DS4_N_EMBD * sizeof(attn_residual[0]));
    float *q = xmalloc((size_t)q_dim * sizeof(q[0]));
    float *kv = xmalloc((size_t)DS4_N_HEAD_DIM * sizeof(kv[0]));
    float *heads = xmalloc((size_t)q_dim * sizeof(heads[0]));
    float *attn_out = xmalloc((size_t)DS4_N_EMBD * sizeof(attn_out[0]));
    float *after_attn_hc = xmalloc((size_t)n_hc * DS4_N_EMBD * sizeof(after_attn_hc[0]));
    float post[4];
    float comb[16];

    memcpy(attn_residual, inp_hc, (size_t)n_hc * DS4_N_EMBD * sizeof(inp_hc[0]));
    hc_pre_from_state_one(model,
                          layer->hc_attn_fn,
                          layer->hc_attn_scale,
                          layer->hc_attn_base,
                          attn_residual, attn_cur, post, comb);

    layer_attn_norm_one(attn_norm, model, layer, attn_cur);
    layer_q_projection_normed_one(model, layer, attn_norm, q);
    layer_kv_projection_normed_one(model, layer, attn_norm, kv);
    rope_tail_layer_inplace(q, DS4_N_HEAD, DS4_N_HEAD_DIM, DS4_N_ROT, pos, il, false);
```<｜Assistant｜></think>