[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
.3f ms execute=%.3f ms\n",
                    (t_embed_encoded - t_layer0) * 1000.0,
                    (t_embed_done - t_embed_encoded) * 1000.0);
        }
    }
    if (!ok) {
        if (ds4_gpu_synchronize() == 0) {
            fprintf(stderr, "ds4: Metal synchronize after layer-major prefill embed failure also failed\n");
        }
        return false;
    }

    for (uint32_t il = 0; ok && il < DS4_N_LAYER; il++) {
        if (split_profile) {
            const double t_attn0 = now_sec();
            ok = ds4_gpu_begin_commands() != 0;
            if (ok) ok = metal_graph_encode_layer_attention_batch(g,
                                                                  model,
                                                                  &weights->layer[il],
                                                                  il,
                                                                  0,
                                                                  (uint32_t)n_tokens);
            const double t_attn_encoded = now_sec();
            if (ok) ok = ds4_gpu_end_commands() != 0;
            const double t_attn_done = now_sec();

            const double t_ffn0 = now_sec();
            if (ok) ok = ds4_gpu_begin_commands() != 0;
            if (ok) ok = metal_graph_encode_layer_ffn_batch(g,
                                                            model,
                                                            &weights->layer[il],
                                                            il,
                                                            0,
                                                            (uint32_t)n_tokens);
            if (ok) {
                ds4_gpu_tensor *tmp = g->batch_cur_hc;
                g->batch_cur_hc = g->batch_next_hc;
                g->batch_next_hc = tmp;
            }
            const double t_ffn_encoded = now_sec();
            if (ok) ok = ds4_gpu_end_commands() != 0;
            const double t_ffn_done = now_sec();
            if (ok && imatrix) ok = imatrix_collect_layer_batch(imatrix, g, il, (uint32_t)n_tokens);

            encode_s += (t_attn_encoded - t_attn0) + (t_ffn_encoded - t_ffn0);
            execute_s += (t_attn_done - t_attn_encoded) + (t_ffn_done - t_ffn_encoded);
            fprintf(stderr,
                    "ds4: metal layer-major prefill layer %u attn encode=%.3f execute=%.3f ms ffn encode=%.3f execute=%.3f ms\n",
                    il,
                    (t_attn_encoded - t_attn0) * 1000.0,
                    (t_attn_done - t_attn_encoded) * 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｜>Trova bug sottili e spiega quali invarianti dell'inferenza possono rompersi.

File: ds4.c

```c
.3f ms execute=%.3f ms\n",
                    (t_embed_encoded - t_layer0) * 1000.0,
                    (t_embed_done - t_embed_encoded) * 1000.0);
        }
    }
    if (!ok) {
        if (ds4_gpu_synchronize() == 0) {
            fprintf(stderr, "ds4: Metal synchronize after layer-major prefill embed failure also failed\n");
        }
        return false;
    }

    for (uint32_t il = 0; ok && il < DS4_N_LAYER; il++) {
        if (split_profile) {
            const double t_attn0 = now_sec();
            ok = ds4_gpu_begin_commands() != 0;
            if (ok) ok = metal_graph_encode_layer_attention_batch(g,
                                                                  model,
                                                                  &weights->layer[il],
                                                                  il,
                                                                  0,
                                                                  (uint32_t)n_tokens);
            const double t_attn_encoded = now_sec();
            if (ok) ok = ds4_gpu_end_commands() != 0;
            const double t_attn_done = now_sec();

            const double t_ffn0 = now_sec();
            if (ok) ok = ds4_gpu_begin_commands() != 0;
            if (ok) ok = metal_graph_encode_layer_ffn_batch(g,
                                                            model,
                                                            &weights->layer[il],
                                                            il,
                                                            0,
                                                            (uint32_t)n_tokens);
            if (ok) {
                ds4_gpu_tensor *tmp = g->batch_cur_hc;
                g->batch_cur_hc = g->batch_next_hc;
                g->batch_next_hc = tmp;
            }
            const double t_ffn_encoded = now_sec();
            if (ok) ok = ds4_gpu_end_commands() != 0;
            const double t_ffn_done = now_sec();
            if (ok && imatrix) ok = imatrix_collect_layer_batch(imatrix, g, il, (uint32_t)n_tokens);

            encode_s += (t_attn_encoded - t_attn0) + (t_ffn_encoded - t_ffn0);
            execute_s += (t_attn_done - t_attn_encoded) + (t_ffn_done - t_ffn_encoded);
            fprintf(stderr,
                    "ds4: metal layer-major prefill layer %u attn encode=%.3f execute=%.3f ms ffn encode=%.3f execute=%.3f ms\n",
                    il,
                    (t_attn_encoded - t_attn0) * 1000.0,
                    (t_attn_done - t_attn_encoded) * 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
ms ffn encode=%.3f execute=%.3f ms\n",
                    il,
                    (t_attn_encoded - t_attn0) * 1000.0,
                    (t_attn_done - t_attn_encoded) * 1000.0,
                    (t_ffn_encoded - t_ffn0) * 1000.0,
                    (t_ffn_done - t_ffn_encoded) * 1000.0);
        } else {
            const double t_chunk0 = profile ? now_sec() : 0.0;
            ok = ds4_gpu_begin_commands() != 0;
            if (ok) ok = metal_graph_encode_layer_batch(g,
                                                        model,
                                                        &weights->layer[il],
                                                        il,
                                                        0,
                                                        (uint32_t)n_tokens);
            const double t_encoded = profile ? now_sec() : 0.0;
            if (ok) ok = ds4_gpu_end_commands() != 0;
            const double t_done = profile ? now_sec() : 0.0;
            if (ok && imatrix) ok = imatrix_collect_layer_batch(imatrix, g, il, (uint32_t)n_tokens);
            if (profile) {
                encode_s += t_encoded - t_chunk0;
                execute_s += t_done - t_encoded;
                fprintf(stderr,
                        "ds4: gpu layer-major prefill layer %u encode=%.3f ms execute=%.3f ms\n",
                        il,
                        (t_encoded - t_chunk0) * 1000.0,
                        (t_done - t_encoded) * 1000.0);
            }
        }
        if (!ok) {
            if (ds4_gpu_synchronize() == 0) {
                fprintf(stderr, "ds4: Metal synchronize after layer-major prefill failure also failed\n");
            }
            return false;
        }
        if (show_progress) {
            fprintf(stderr, "ds4: gpu prefill layer %u/%u\r", il + 1, (uint32_t)DS4_N_LAYER);
            fflush(stderr);
        }
    }
    if (show_progress) fputc('\n', stderr);

    const uint64_t hc_dim = (uint64_t)DS4_N_HC * DS4_N_EMBD;
    uint32_t output_row = (uint32_t)n_tokens - 1u;
    const char *output_row_env = getenv("DS4_METAL_GRAPH_OUTPUT_ROW");
    if (output_row_env && output_row_env[0]) {
        char *end = NULL;
        unsigned long v = strtoul(output_row_env, &end, 10);
        if (end != output_row_env && v < (unsigned long)n_tokens) {
            output_row = (uint32_t)v;
        }
    }
    ds4_gpu_tensor *last_hc = metal_graph_tensor_row_view(g->batch_cur_hc,
                                                            output_row,
```

<｜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
ms ffn encode=%.3f execute=%.3f ms\n",
                    il,
                    (t_attn_encoded - t_attn0) * 1000.0,
                    (t_attn_done - t_attn_encoded) * 1000.0,
                    (t_ffn_encoded - t_ffn0) * 1000.0,
                    (t_ffn_done - t_ffn_encoded) * 1000.0);
        } else {
            const double t_chunk0 = profile ? now_sec() : 0.0;
            ok = ds4_gpu_begin_commands() != 0;
            if (ok) ok = metal_graph_encode_layer_batch(g,
                                                        model,
                                                        &weights->layer[il],
                                                        il,
                                                        0,
                                                        (uint32_t)n_tokens);
            const double t_encoded = profile ? now_sec() : 0.0;
            if (ok) ok = ds4_gpu_end_commands() != 0;
            const double t_done = profile ? now_sec() : 0.0;
            if (ok && imatrix) ok = imatrix_collect_layer_batch(imatrix, g, il, (uint32_t)n_tokens);
            if (profile) {
                encode_s += t_encoded - t_chunk0;
                execute_s += t_done - t_encoded;
                fprintf(stderr,
                        "ds4: gpu layer-major prefill layer %u encode=%.3f ms execute=%.3f ms\n",
                        il,
                        (t_encoded - t_chunk0) * 1000.0,
                        (t_done - t_encoded) * 1000.0);
            }
        }
        if (!ok) {
            if (ds4_gpu_synchronize() == 0) {
                fprintf(stderr, "ds4: Metal synchronize after layer-major prefill failure also failed\n");
            }
            return false;
        }
        if (show_progress) {
            fprintf(stderr, "ds4: gpu prefill layer %u/%u\r", il + 1, (uint32_t)DS4_N_LAYER);
            fflush(stderr);
        }
    }
    if (show_progress) fputc('\n', stderr);

    const uint64_t hc_dim = (uint64_t)DS4_N_HC * DS4_N_EMBD;
    uint32_t output_row = (uint32_t)n_tokens - 1u;
    const char *output_row_env = getenv("DS4_METAL_GRAPH_OUTPUT_ROW");
    if (output_row_env && output_row_env[0]) {
        char *end = NULL;
        unsigned long v = strtoul(output_row_env, &end, 10);
        if (end != output_row_env && v < (unsigned long)n_tokens) {
            output_row = (uint32_t)v;
        }
    }
    ds4_gpu_tensor *last_hc = metal_graph_tensor_row_view(g->batch_cur_hc,
                                                            output_row,
```<｜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
ms ffn encode=%.3f execute=%.3f ms\n",
                    il,
                    (t_attn_encoded - t_attn0) * 1000.0,
                    (t_attn_done - t_attn_encoded) * 1000.0,
                    (t_ffn_encoded - t_ffn0) * 1000.0,
                    (t_ffn_done - t_ffn_encoded) * 1000.0);
        } else {
            const double t_chunk0 = profile ? now_sec() : 0.0;
            ok = ds4_gpu_begin_commands() != 0;
            if (ok) ok = metal_graph_encode_layer_batch(g,
                                                        model,
                                                        &weights->layer[il],
                                                        il,
                                                        0,
                                                        (uint32_t)n_tokens);
            const double t_encoded = profile ? now_sec() : 0.0;
            if (ok) ok = ds4_gpu_end_commands() != 0;
            const double t_done = profile ? now_sec() : 0.0;
            if (ok && imatrix) ok = imatrix_collect_layer_batch(imatrix, g, il, (uint32_t)n_tokens);
            if (profile) {
                encode_s += t_encoded - t_chunk0;
                execute_s += t_done - t_encoded;
                fprintf(stderr,
                        "ds4: gpu layer-major prefill layer %u encode=%.3f ms execute=%.3f ms\n",
                        il,
                        (t_encoded - t_chunk0) * 1000.0,
                        (t_done - t_encoded) * 1000.0);
            }
        }
        if (!ok) {
            if (ds4_gpu_synchronize() == 0) {
                fprintf(stderr, "ds4: Metal synchronize after layer-major prefill failure also failed\n");
            }
            return false;
        }
        if (show_progress) {
            fprintf(stderr, "ds4: gpu prefill layer %u/%u\r", il + 1, (uint32_t)DS4_N_LAYER);
            fflush(stderr);
        }
    }
    if (show_progress) fputc('\n', stderr);

    const uint64_t hc_dim = (uint64_t)DS4_N_HC * DS4_N_EMBD;
    uint32_t output_row = (uint32_t)n_tokens - 1u;
    const char *output_row_env = getenv("DS4_METAL_GRAPH_OUTPUT_ROW");
    if (output_row_env && output_row_env[0]) {
        char *end = NULL;
        unsigned long v = strtoul(output_row_env, &end, 10);
        if (end != output_row_env && v < (unsigned long)n_tokens) {
            output_row = (uint32_t)v;
        }
    }
    ds4_gpu_tensor *last_hc = metal_graph_tensor_row_view(g->batch_cur_hc,
                                                            output_row,
```

<｜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
ms ffn encode=%.3f execute=%.3f ms\n",
                    il,
                    (t_attn_encoded - t_attn0) * 1000.0,
                    (t_attn_done - t_attn_encoded) * 1000.0,
                    (t_ffn_encoded - t_ffn0) * 1000.0,
                    (t_ffn_done - t_ffn_encoded) * 1000.0);
        } else {
            const double t_chunk0 = profile ? now_sec() : 0.0;
            ok = ds4_gpu_begin_commands() != 0;
            if (ok) ok = metal_graph_encode_layer_batch(g,
                                                        model,
                                                        &weights->layer[il],
                                                        il,
                                                        0,
                                                        (uint32_t)n_tokens);
            const double t_encoded = profile ? now_sec() : 0.0;
            if (ok) ok = ds4_gpu_end_commands() != 0;
            const double t_done = profile ? now_sec() : 0.0;
            if (ok && imatrix) ok = imatrix_collect_layer_batch(imatrix, g, il, (uint32_t)n_tokens);
            if (profile) {
                encode_s += t_encoded - t_chunk0;
                execute_s += t_done - t_encoded;
                fprintf(stderr,
                        "ds4: gpu layer-major prefill layer %u encode=%.3f ms execute=%.3f ms\n",
                        il,
                        (t_encoded - t_chunk0) * 1000.0,
                        (t_done - t_encoded) * 1000.0);
            }
        }
        if (!ok) {
            if (ds4_gpu_synchronize() == 0) {
                fprintf(stderr, "ds4: Metal synchronize after layer-major prefill failure also failed\n");
            }
            return false;
        }
        if (show_progress) {
            fprintf(stderr, "ds4: gpu prefill layer %u/%u\r", il + 1, (uint32_t)DS4_N_LAYER);
            fflush(stderr);
        }
    }
    if (show_progress) fputc('\n', stderr);

    const uint64_t hc_dim = (uint64_t)DS4_N_HC * DS4_N_EMBD;
    uint32_t output_row = (uint32_t)n_tokens - 1u;
    const char *output_row_env = getenv("DS4_METAL_GRAPH_OUTPUT_ROW");
    if (output_row_env && output_row_env[0]) {
        char *end = NULL;
        unsigned long v = strtoul(output_row_env, &end, 10);
        if (end != output_row_env && v < (unsigned long)n_tokens) {
            output_row = (uint32_t)v;
        }
    }
    ds4_gpu_tensor *last_hc = metal_graph_tensor_row_view(g->batch_cur_hc,
                                                            output_row,
```<｜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
ow = (uint32_t)v;
        }
    }
    ds4_gpu_tensor *last_hc = metal_graph_tensor_row_view(g->batch_cur_hc,
                                                            output_row,
                                                            hc_dim);
    if (!last_hc) return false;
    ds4_gpu_tensor *saved_cur = g->cur_hc;
    g->cur_hc = last_hc;

    const double t_head0 = profile ? now_sec() : 0.0;
    ok = ds4_gpu_begin_commands() != 0;
    if (ok) ok = metal_graph_encode_output_head(g, model, weights, weights->output->dim[1]);
    const double t_head_encoded = profile ? now_sec() : 0.0;
    if (ok) ok = ds4_gpu_end_commands() != 0;
    const double t_head_done = profile ? now_sec() : 0.0;
    g->cur_hc = saved_cur;
    ds4_gpu_tensor_free(last_hc);
    if (!ok) return false;

    const double t_before_read = profile ? now_sec() : 0.0;
    if (logits) {
        ok = ds4_gpu_tensor_read(g->logits, 0, logits, (uint64_t)DS4_N_VOCAB * sizeof(float)) != 0;
    }
    if (profile) {
        const double t_read = now_sec();
        encode_s += t_head_encoded - t_head0;
        execute_s += t_head_done - t_head_encoded;
        if (split_profile) {
            fprintf(stderr,
                    "ds4: gpu layer-major prefill head encode=%.3f ms execute=%.3f ms\n",
                    (t_head_encoded - t_head0) * 1000.0,
                    (t_head_done - t_head_encoded) * 1000.0);
        }
        fprintf(stderr,
                "ds4: gpu layer-major prefill total tokens=%d encode=%.3f ms execute=%.3f ms read=%.3f ms total=%.3f ms\n",
                n_tokens,
                encode_s * 1000.0,
                execute_s * 1000.0,
                (t_read - t_before_read) * 1000.0,
                (t_read - t0) * 1000.0);
    }
    return ok;
}

static bool metal_graph_prefill_raw_swa(
        ds4_gpu_graph *g,
        const ds4_model       *model,
        const ds4_weights     *weights,
        const token_vec       *prompt,
        int                    n_tokens,
        float                 *logits,
        bool                   show_progress) {
    if (n_tokens <= 0 || n_tokens > prompt->len) return false;
    if ((uint32_t)n_tokens > g->prefill_cap) return false;
    return metal_graph_prefill_layer_major(g, model, weights, prompt, n_tokens, logits, show_progress, NULL);
}

static bool metal_graph_prefill_batch_row_logits(
        ds4_gpu_graph *g,
        const ds4_model   *model,
        const ds4_weights *weights,
        uint32_t           batch_row,
        float             *logits) {
    if (!logits) return true;
```

<｜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
ow = (uint32_t)v;
        }
    }
    ds4_gpu_tensor *last_hc = metal_graph_tensor_row_view(g->batch_cur_hc,
                                                            output_row,
                                                            hc_dim);
    if (!last_hc) return false;
    ds4_gpu_tensor *saved_cur = g->cur_hc;
    g->cur_hc = last_hc;

    const double t_head0 = profile ? now_sec() : 0.0;
    ok = ds4_gpu_begin_commands() != 0;
    if (ok) ok = metal_graph_encode_output_head(g, model, weights, weights->output->dim[1]);
    const double t_head_encoded = profile ? now_sec() : 0.0;
    if (ok) ok = ds4_gpu_end_commands() != 0;
    const double t_head_done = profile ? now_sec() : 0.0;
    g->cur_hc = saved_cur;
    ds4_gpu_tensor_free(last_hc);
    if (!ok) return false;

    const double t_before_read = profile ? now_sec() : 0.0;
    if (logits) {
        ok = ds4_gpu_tensor_read(g->logits, 0, logits, (uint64_t)DS4_N_VOCAB * sizeof(float)) != 0;
    }
    if (profile) {
        const double t_read = now_sec();
        encode_s += t_head_encoded - t_head0;
        execute_s += t_head_done - t_head_encoded;
        if (split_profile) {
            fprintf(stderr,
                    "ds4: gpu layer-major prefill head encode=%.3f ms execute=%.3f ms\n",
                    (t_head_encoded - t_head0) * 1000.0,
                    (t_head_done - t_head_encoded) * 1000.0);
        }
        fprintf(stderr,
                "ds4: gpu layer-major prefill total tokens=%d encode=%.3f ms execute=%.3f ms read=%.3f ms total=%.3f ms\n",
                n_tokens,
                encode_s * 1000.0,
                execute_s * 1000.0,
                (t_read - t_before_read) * 1000.0,
                (t_read - t0) * 1000.0);
    }
    return ok;
}

static bool metal_graph_prefill_raw_swa(
        ds4_gpu_graph *g,
        const ds4_model       *model,
        const ds4_weights     *weights,
        const token_vec       *prompt,
        int                    n_tokens,
        float                 *logits,
        bool                   show_progress) {
    if (n_tokens <= 0 || n_tokens > prompt->len) return false;
    if ((uint32_t)n_tokens > g->prefill_cap) return false;
    return metal_graph_prefill_layer_major(g, model, weights, prompt, n_tokens, logits, show_progress, NULL);
}

static bool metal_graph_prefill_batch_row_logits(
        ds4_gpu_graph *g,
        const ds4_model   *model,
        const ds4_weights *weights,
        uint32_t           batch_row,
        float             *logits) {
    if (!logits) return true;
```<｜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
ow = (uint32_t)v;
        }
    }
    ds4_gpu_tensor *last_hc = metal_graph_tensor_row_view(g->batch_cur_hc,
                                                            output_row,
                                                            hc_dim);
    if (!last_hc) return false;
    ds4_gpu_tensor *saved_cur = g->cur_hc;
    g->cur_hc = last_hc;

    const double t_head0 = profile ? now_sec() : 0.0;
    ok = ds4_gpu_begin_commands() != 0;
    if (ok) ok = metal_graph_encode_output_head(g, model, weights, weights->output->dim[1]);
    const double t_head_encoded = profile ? now_sec() : 0.0;
    if (ok) ok = ds4_gpu_end_commands() != 0;
    const double t_head_done = profile ? now_sec() : 0.0;
    g->cur_hc = saved_cur;
    ds4_gpu_tensor_free(last_hc);
    if (!ok) return false;

    const double t_before_read = profile ? now_sec() : 0.0;
    if (logits) {
        ok = ds4_gpu_tensor_read(g->logits, 0, logits, (uint64_t)DS4_N_VOCAB * sizeof(float)) != 0;
    }
    if (profile) {
        const double t_read = now_sec();
        encode_s += t_head_encoded - t_head0;
        execute_s += t_head_done - t_head_encoded;
        if (split_profile) {
            fprintf(stderr,
                    "ds4: gpu layer-major prefill head encode=%.3f ms execute=%.3f ms\n",
                    (t_head_encoded - t_head0) * 1000.0,
                    (t_head_done - t_head_encoded) * 1000.0);
        }
        fprintf(stderr,
                "ds4: gpu layer-major prefill total tokens=%d encode=%.3f ms execute=%.3f ms read=%.3f ms total=%.3f ms\n",
                n_tokens,
                encode_s * 1000.0,
                execute_s * 1000.0,
                (t_read - t_before_read) * 1000.0,
                (t_read - t0) * 1000.0);
    }
    return ok;
}

static bool metal_graph_prefill_raw_swa(
        ds4_gpu_graph *g,
        const ds4_model       *model,
        const ds4_weights     *weights,
        const token_vec       *prompt,
        int                    n_tokens,
        float                 *logits,
        bool                   show_progress) {
    if (n_tokens <= 0 || n_tokens > prompt->len) return false;
    if ((uint32_t)n_tokens > g->prefill_cap) return false;
    return metal_graph_prefill_layer_major(g, model, weights, prompt, n_tokens, logits, show_progress, NULL);
}

static bool metal_graph_prefill_batch_row_logits(
        ds4_gpu_graph *g,
        const ds4_model   *model,
        const ds4_weights *weights,
        uint32_t           batch_row,
        float             *logits) {
    if (!logits) return true;
```

<｜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
ow = (uint32_t)v;
        }
    }
    ds4_gpu_tensor *last_hc = metal_graph_tensor_row_view(g->batch_cur_hc,
                                                            output_row,
                                                            hc_dim);
    if (!last_hc) return false;
    ds4_gpu_tensor *saved_cur = g->cur_hc;
    g->cur_hc = last_hc;

    const double t_head0 = profile ? now_sec() : 0.0;
    ok = ds4_gpu_begin_commands() != 0;
    if (ok) ok = metal_graph_encode_output_head(g, model, weights, weights->output->dim[1]);
    const double t_head_encoded = profile ? now_sec() : 0.0;
    if (ok) ok = ds4_gpu_end_commands() != 0;
    const double t_head_done = profile ? now_sec() : 0.0;
    g->cur_hc = saved_cur;
    ds4_gpu_tensor_free(last_hc);
    if (!ok) return false;

    const double t_before_read = profile ? now_sec() : 0.0;
    if (logits) {
        ok = ds4_gpu_tensor_read(g->logits, 0, logits, (uint64_t)DS4_N_VOCAB * sizeof(float)) != 0;
    }
    if (profile) {
        const double t_read = now_sec();
        encode_s += t_head_encoded - t_head0;
        execute_s += t_head_done - t_head_encoded;
        if (split_profile) {
            fprintf(stderr,
                    "ds4: gpu layer-major prefill head encode=%.3f ms execute=%.3f ms\n",
                    (t_head_encoded - t_head0) * 1000.0,
                    (t_head_done - t_head_encoded) * 1000.0);
        }
        fprintf(stderr,
                "ds4: gpu layer-major prefill total tokens=%d encode=%.3f ms execute=%.3f ms read=%.3f ms total=%.3f ms\n",
                n_tokens,
                encode_s * 1000.0,
                execute_s * 1000.0,
                (t_read - t_before_read) * 1000.0,
                (t_read - t0) * 1000.0);
    }
    return ok;
}

static bool metal_graph_prefill_raw_swa(
        ds4_gpu_graph *g,
        const ds4_model       *model,
        const ds4_weights     *weights,
        const token_vec       *prompt,
        int                    n_tokens,
        float                 *logits,
        bool                   show_progress) {
    if (n_tokens <= 0 || n_tokens > prompt->len) return false;
    if ((uint32_t)n_tokens > g->prefill_cap) return false;
    return metal_graph_prefill_layer_major(g, model, weights, prompt, n_tokens, logits, show_progress, NULL);
}

static bool metal_graph_prefill_batch_row_logits(
        ds4_gpu_graph *g,
        const ds4_model   *model,
        const ds4_weights *weights,
        uint32_t           batch_row,
        float             *logits) {
    if (!logits) return true;
```<｜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
h *g,
        const ds4_model   *model,
        const ds4_weights *weights,
        uint32_t           batch_row,
        float             *logits) {
    if (!logits) return true;
    const uint64_t hc_dim = (uint64_t)DS4_N_HC * DS4_N_EMBD;
    ds4_gpu_tensor *last_hc = metal_graph_tensor_row_view(g->batch_cur_hc,
                                                            batch_row,
                                                            hc_dim);
    if (!last_hc) return false;
    ds4_gpu_tensor *saved_cur = g->cur_hc;
    g->cur_hc = last_hc;
    bool ok = ds4_gpu_begin_commands() != 0;
    if (ok) ok = metal_graph_encode_output_head(g, model, weights, weights->output->dim[1]);
    if (ok) ok = ds4_gpu_end_commands() != 0;
    else (void)ds4_gpu_synchronize();
    g->cur_hc = saved_cur;
    ds4_gpu_tensor_free(last_hc);
    if (!ok) return false;
    return ds4_gpu_tensor_read(g->logits, 0, logits,
                                 (uint64_t)DS4_N_VOCAB * sizeof(float)) != 0;
}

/* Prefill a contiguous token range in fixed-size chunks.
 *
 * The common case starts at token zero, but server sessions also use this to
 * extend an existing KV cache with a long suffix.  Resumed chunks are aligned
 * to the same absolute prefill-cap boundaries used by a cold full prompt, so
 * compression windows and row finalization follow the same schedule after the
 * cached prefix.
 */
static bool metal_graph_prefill_chunked_range(
        ds4_gpu_graph *g,
        const ds4_model       *model,
        const ds4_weights     *weights,
        const token_vec       *prompt,
        uint32_t               start,
        uint32_t               n_tokens,
        float                 *logits,
        bool                   show_progress,
        ds4_session_progress_fn progress,
        void                  *progress_ud,
        ds4_imatrix_collector *imatrix) {
    if (n_tokens == 0 || g->prefill_cap == 0) return false;
    if (start > (uint32_t)prompt->len) return false;
    if (n_tokens > (uint32_t)prompt->len - start) return false;

    uint32_t chunk_cap = g->prefill_cap;
    if (start != 0 && chunk_cap > g->raw_cap) chunk_cap = g->raw_cap;
    if (chunk_cap == 0) return false;

    uint32_t first_chunk = n_tokens < chunk_cap ? n_tokens : chunk_cap;
    if (start != 0 && g->prefill_cap != 0) {
        const uint32_t mod = start % g->prefill_cap;
        if (mod != 0) {
            const uint32_t to_boundary = g->prefill_cap - mod;
            if (to_boundary < first_chunk) first_chunk = to_boundary;
        }
    }
```

<｜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
h *g,
        const ds4_model   *model,
        const ds4_weights *weights,
        uint32_t           batch_row,
        float             *logits) {
    if (!logits) return true;
    const uint64_t hc_dim = (uint64_t)DS4_N_HC * DS4_N_EMBD;
    ds4_gpu_tensor *last_hc = metal_graph_tensor_row_view(g->batch_cur_hc,
                                                            batch_row,
                                                            hc_dim);
    if (!last_hc) return false;
    ds4_gpu_tensor *saved_cur = g->cur_hc;
    g->cur_hc = last_hc;
    bool ok = ds4_gpu_begin_commands() != 0;
    if (ok) ok = metal_graph_encode_output_head(g, model, weights, weights->output->dim[1]);
    if (ok) ok = ds4_gpu_end_commands() != 0;
    else (void)ds4_gpu_synchronize();
    g->cur_hc = saved_cur;
    ds4_gpu_tensor_free(last_hc);
    if (!ok) return false;
    return ds4_gpu_tensor_read(g->logits, 0, logits,
                                 (uint64_t)DS4_N_VOCAB * sizeof(float)) != 0;
}

/* Prefill a contiguous token range in fixed-size chunks.
 *
 * The common case starts at token zero, but server sessions also use this to
 * extend an existing KV cache with a long suffix.  Resumed chunks are aligned
 * to the same absolute prefill-cap boundaries used by a cold full prompt, so
 * compression windows and row finalization follow the same schedule after the
 * cached prefix.
 */
static bool metal_graph_prefill_chunked_range(
        ds4_gpu_graph *g,
        const ds4_model       *model,
        const ds4_weights     *weights,
        const token_vec       *prompt,
        uint32_t               start,
        uint32_t               n_tokens,
        float                 *logits,
        bool                   show_progress,
        ds4_session_progress_fn progress,
        void                  *progress_ud,
        ds4_imatrix_collector *imatrix) {
    if (n_tokens == 0 || g->prefill_cap == 0) return false;
    if (start > (uint32_t)prompt->len) return false;
    if (n_tokens > (uint32_t)prompt->len - start) return false;

    uint32_t chunk_cap = g->prefill_cap;
    if (start != 0 && chunk_cap > g->raw_cap) chunk_cap = g->raw_cap;
    if (chunk_cap == 0) return false;

    uint32_t first_chunk = n_tokens < chunk_cap ? n_tokens : chunk_cap;
    if (start != 0 && g->prefill_cap != 0) {
        const uint32_t mod = start % g->prefill_cap;
        if (mod != 0) {
            const uint32_t to_boundary = g->prefill_cap - mod;
            if (to_boundary < first_chunk) first_chunk = to_boundary;
        }
    }
```<｜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
h *g,
        const ds4_model   *model,
        const ds4_weights *weights,
        uint32_t           batch_row,
        float             *logits) {
    if (!logits) return true;
    const uint64_t hc_dim = (uint64_t)DS4_N_HC * DS4_N_EMBD;
    ds4_gpu_tensor *last_hc = metal_graph_tensor_row_view(g->batch_cur_hc,
                                                            batch_row,
                                                            hc_dim);
    if (!last_hc) return false;
    ds4_gpu_tensor *saved_cur = g->cur_hc;
    g->cur_hc = last_hc;
    bool ok = ds4_gpu_begin_commands() != 0;
    if (ok) ok = metal_graph_encode_output_head(g, model, weights, weights->output->dim[1]);
    if (ok) ok = ds4_gpu_end_commands() != 0;
    else (void)ds4_gpu_synchronize();
    g->cur_hc = saved_cur;
    ds4_gpu_tensor_free(last_hc);
    if (!ok) return false;
    return ds4_gpu_tensor_read(g->logits, 0, logits,
                                 (uint64_t)DS4_N_VOCAB * sizeof(float)) != 0;
}

/* Prefill a contiguous token range in fixed-size chunks.
 *
 * The common case starts at token zero, but server sessions also use this to
 * extend an existing KV cache with a long suffix.  Resumed chunks are aligned
 * to the same absolute prefill-cap boundaries used by a cold full prompt, so
 * compression windows and row finalization follow the same schedule after the
 * cached prefix.
 */
static bool metal_graph_prefill_chunked_range(
        ds4_gpu_graph *g,
        const ds4_model       *model,
        const ds4_weights     *weights,
        const token_vec       *prompt,
        uint32_t               start,
        uint32_t               n_tokens,
        float                 *logits,
        bool                   show_progress,
        ds4_session_progress_fn progress,
        void                  *progress_ud,
        ds4_imatrix_collector *imatrix) {
    if (n_tokens == 0 || g->prefill_cap == 0) return false;
    if (start > (uint32_t)prompt->len) return false;
    if (n_tokens > (uint32_t)prompt->len - start) return false;

    uint32_t chunk_cap = g->prefill_cap;
    if (start != 0 && chunk_cap > g->raw_cap) chunk_cap = g->raw_cap;
    if (chunk_cap == 0) return false;

    uint32_t first_chunk = n_tokens < chunk_cap ? n_tokens : chunk_cap;
    if (start != 0 && g->prefill_cap != 0) {
        const uint32_t mod = start % g->prefill_cap;
        if (mod != 0) {
            const uint32_t to_boundary = g->prefill_cap - mod;
            if (to_boundary < first_chunk) first_chunk = to_boundary;
        }
    }
```

<｜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
h *g,
        const ds4_model   *model,
        const ds4_weights *weights,
        uint32_t           batch_row,
        float             *logits) {
    if (!logits) return true;
    const uint64_t hc_dim = (uint64_t)DS4_N_HC * DS4_N_EMBD;
    ds4_gpu_tensor *last_hc = metal_graph_tensor_row_view(g->batch_cur_hc,
                                                            batch_row,
                                                            hc_dim);
    if (!last_hc) return false;
    ds4_gpu_tensor *saved_cur = g->cur_hc;
    g->cur_hc = last_hc;
    bool ok = ds4_gpu_begin_commands() != 0;
    if (ok) ok = metal_graph_encode_output_head(g, model, weights, weights->output->dim[1]);
    if (ok) ok = ds4_gpu_end_commands() != 0;
    else (void)ds4_gpu_synchronize();
    g->cur_hc = saved_cur;
    ds4_gpu_tensor_free(last_hc);
    if (!ok) return false;
    return ds4_gpu_tensor_read(g->logits, 0, logits,
                                 (uint64_t)DS4_N_VOCAB * sizeof(float)) != 0;
}

/* Prefill a contiguous token range in fixed-size chunks.
 *
 * The common case starts at token zero, but server sessions also use this to
 * extend an existing KV cache with a long suffix.  Resumed chunks are aligned
 * to the same absolute prefill-cap boundaries used by a cold full prompt, so
 * compression windows and row finalization follow the same schedule after the
 * cached prefix.
 */
static bool metal_graph_prefill_chunked_range(
        ds4_gpu_graph *g,
        const ds4_model       *model,
        const ds4_weights     *weights,
        const token_vec       *prompt,
        uint32_t               start,
        uint32_t               n_tokens,
        float                 *logits,
        bool                   show_progress,
        ds4_session_progress_fn progress,
        void                  *progress_ud,
        ds4_imatrix_collector *imatrix) {
    if (n_tokens == 0 || g->prefill_cap == 0) return false;
    if (start > (uint32_t)prompt->len) return false;
    if (n_tokens > (uint32_t)prompt->len - start) return false;

    uint32_t chunk_cap = g->prefill_cap;
    if (start != 0 && chunk_cap > g->raw_cap) chunk_cap = g->raw_cap;
    if (chunk_cap == 0) return false;

    uint32_t first_chunk = n_tokens < chunk_cap ? n_tokens : chunk_cap;
    if (start != 0 && g->prefill_cap != 0) {
        const uint32_t mod = start % g->prefill_cap;
        if (mod != 0) {
            const uint32_t to_boundary = g->prefill_cap - mod;
            if (to_boundary < first_chunk) first_chunk = to_boundary;
        }
    }
```<｜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
ll_cap;
        if (mod != 0) {
            const uint32_t to_boundary = g->prefill_cap - mod;
            if (to_boundary < first_chunk) first_chunk = to_boundary;
        }
    }
    if (!metal_graph_warmup_prefill_kernels(g, model, weights, first_chunk)) return false;

    const bool profile = getenv("DS4_METAL_GRAPH_PREFILL_PROFILE") != NULL;
    const double t0 = profile ? now_sec() : 0.0;
    double encode_s = 0.0;
    double execute_s = 0.0;
    uint32_t last_chunk_tokens = 0;
    const uint32_t end = start + n_tokens;

    if (progress) {
        progress(progress_ud, "prefill_chunk", (int)start, prompt->len);
    }

    for (uint32_t pos0 = start; pos0 < end; ) {
        const uint32_t remaining = end - pos0;
        uint32_t local_cap = chunk_cap;
        if (start != 0 && g->prefill_cap != 0) {
            const uint32_t mod = pos0 % g->prefill_cap;
            if (mod != 0) {
                const uint32_t to_boundary = g->prefill_cap - mod;
                if (to_boundary < local_cap) local_cap = to_boundary;
            }
        }
        const uint32_t chunk = remaining < local_cap ? remaining : local_cap;
        last_chunk_tokens = chunk;

        bool ok = metal_graph_upload_prompt_tokens(g->prefill_tokens, prompt, pos0, chunk);
        if (ok) ok = metal_graph_upload_prompt_embeddings_hc(g->batch_cur_hc,
                                                             g->prefill_tokens,
                                                             model,
                                                             weights,
                                                             prompt,
                                                             pos0,
                                                             chunk);
        if (!ok) return false;

        for (uint32_t il = 0; ok && il < DS4_N_LAYER; il++) {
            const double t_layer0 = profile ? now_sec() : 0.0;
            ok = ds4_gpu_begin_commands() != 0;
            if (ok) ok = metal_graph_encode_layer_batch(g,
                                                        model,
                                                        &weights->layer[il],
                                                        il,
                                                        pos0,
                                                        chunk);
            const double t_encoded = profile ? now_sec() : 0.0;
            if (ok) ok = ds4_gpu_end_commands() != 0;
            const double t_done = 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
ll_cap;
        if (mod != 0) {
            const uint32_t to_boundary = g->prefill_cap - mod;
            if (to_boundary < first_chunk) first_chunk = to_boundary;
        }
    }
    if (!metal_graph_warmup_prefill_kernels(g, model, weights, first_chunk)) return false;

    const bool profile = getenv("DS4_METAL_GRAPH_PREFILL_PROFILE") != NULL;
    const double t0 = profile ? now_sec() : 0.0;
    double encode_s = 0.0;
    double execute_s = 0.0;
    uint32_t last_chunk_tokens = 0;
    const uint32_t end = start + n_tokens;

    if (progress) {
        progress(progress_ud, "prefill_chunk", (int)start, prompt->len);
    }

    for (uint32_t pos0 = start; pos0 < end; ) {
        const uint32_t remaining = end - pos0;
        uint32_t local_cap = chunk_cap;
        if (start != 0 && g->prefill_cap != 0) {
            const uint32_t mod = pos0 % g->prefill_cap;
            if (mod != 0) {
                const uint32_t to_boundary = g->prefill_cap - mod;
                if (to_boundary < local_cap) local_cap = to_boundary;
            }
        }
        const uint32_t chunk = remaining < local_cap ? remaining : local_cap;
        last_chunk_tokens = chunk;

        bool ok = metal_graph_upload_prompt_tokens(g->prefill_tokens, prompt, pos0, chunk);
        if (ok) ok = metal_graph_upload_prompt_embeddings_hc(g->batch_cur_hc,
                                                             g->prefill_tokens,
                                                             model,
                                                             weights,
                                                             prompt,
                                                             pos0,
                                                             chunk);
        if (!ok) return false;

        for (uint32_t il = 0; ok && il < DS4_N_LAYER; il++) {
            const double t_layer0 = profile ? now_sec() : 0.0;
            ok = ds4_gpu_begin_commands() != 0;
            if (ok) ok = metal_graph_encode_layer_batch(g,
                                                        model,
                                                        &weights->layer[il],
                                                        il,
                                                        pos0,
                                                        chunk);
            const double t_encoded = profile ? now_sec() : 0.0;
            if (ok) ok = ds4_gpu_end_commands() != 0;
            const double t_done = 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
ll_cap;
        if (mod != 0) {
            const uint32_t to_boundary = g->prefill_cap - mod;
            if (to_boundary < first_chunk) first_chunk = to_boundary;
        }
    }
    if (!metal_graph_warmup_prefill_kernels(g, model, weights, first_chunk)) return false;

    const bool profile = getenv("DS4_METAL_GRAPH_PREFILL_PROFILE") != NULL;
    const double t0 = profile ? now_sec() : 0.0;
    double encode_s = 0.0;
    double execute_s = 0.0;
    uint32_t last_chunk_tokens = 0;
    const uint32_t end = start + n_tokens;

    if (progress) {
        progress(progress_ud, "prefill_chunk", (int)start, prompt->len);
    }

    for (uint32_t pos0 = start; pos0 < end; ) {
        const uint32_t remaining = end - pos0;
        uint32_t local_cap = chunk_cap;
        if (start != 0 && g->prefill_cap != 0) {
            const uint32_t mod = pos0 % g->prefill_cap;
            if (mod != 0) {
                const uint32_t to_boundary = g->prefill_cap - mod;
                if (to_boundary < local_cap) local_cap = to_boundary;
            }
        }
        const uint32_t chunk = remaining < local_cap ? remaining : local_cap;
        last_chunk_tokens = chunk;

        bool ok = metal_graph_upload_prompt_tokens(g->prefill_tokens, prompt, pos0, chunk);
        if (ok) ok = metal_graph_upload_prompt_embeddings_hc(g->batch_cur_hc,
                                                             g->prefill_tokens,
                                                             model,
                                                             weights,
                                                             prompt,
                                                             pos0,
                                                             chunk);
        if (!ok) return false;

        for (uint32_t il = 0; ok && il < DS4_N_LAYER; il++) {
            const double t_layer0 = profile ? now_sec() : 0.0;
            ok = ds4_gpu_begin_commands() != 0;
            if (ok) ok = metal_graph_encode_layer_batch(g,
                                                        model,
                                                        &weights->layer[il],
                                                        il,
                                                        pos0,
                                                        chunk);
            const double t_encoded = profile ? now_sec() : 0.0;
            if (ok) ok = ds4_gpu_end_commands() != 0;
            const double t_done = 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
ll_cap;
        if (mod != 0) {
            const uint32_t to_boundary = g->prefill_cap - mod;
            if (to_boundary < first_chunk) first_chunk = to_boundary;
        }
    }
    if (!metal_graph_warmup_prefill_kernels(g, model, weights, first_chunk)) return false;

    const bool profile = getenv("DS4_METAL_GRAPH_PREFILL_PROFILE") != NULL;
    const double t0 = profile ? now_sec() : 0.0;
    double encode_s = 0.0;
    double execute_s = 0.0;
    uint32_t last_chunk_tokens = 0;
    const uint32_t end = start + n_tokens;

    if (progress) {
        progress(progress_ud, "prefill_chunk", (int)start, prompt->len);
    }

    for (uint32_t pos0 = start; pos0 < end; ) {
        const uint32_t remaining = end - pos0;
        uint32_t local_cap = chunk_cap;
        if (start != 0 && g->prefill_cap != 0) {
            const uint32_t mod = pos0 % g->prefill_cap;
            if (mod != 0) {
                const uint32_t to_boundary = g->prefill_cap - mod;
                if (to_boundary < local_cap) local_cap = to_boundary;
            }
        }
        const uint32_t chunk = remaining < local_cap ? remaining : local_cap;
        last_chunk_tokens = chunk;

        bool ok = metal_graph_upload_prompt_tokens(g->prefill_tokens, prompt, pos0, chunk);
        if (ok) ok = metal_graph_upload_prompt_embeddings_hc(g->batch_cur_hc,
                                                             g->prefill_tokens,
                                                             model,
                                                             weights,
                                                             prompt,
                                                             pos0,
                                                             chunk);
        if (!ok) return false;

        for (uint32_t il = 0; ok && il < DS4_N_LAYER; il++) {
            const double t_layer0 = profile ? now_sec() : 0.0;
            ok = ds4_gpu_begin_commands() != 0;
            if (ok) ok = metal_graph_encode_layer_batch(g,
                                                        model,
                                                        &weights->layer[il],
                                                        il,
                                                        pos0,
                                                        chunk);
            const double t_encoded = profile ? now_sec() : 0.0;
            if (ok) ok = ds4_gpu_end_commands() != 0;
            const double t_done = 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
;
            const double t_encoded = profile ? now_sec() : 0.0;
            if (ok) ok = ds4_gpu_end_commands() != 0;
            const double t_done = profile ? now_sec() : 0.0;
            if (ok && imatrix) ok = imatrix_collect_layer_batch(imatrix, g, il, chunk);
            if (profile) {
                encode_s += t_encoded - t_layer0;
                execute_s += t_done - t_encoded;
                fprintf(stderr,
                        "ds4: gpu chunked prefill pos=%u tokens=%u layer %u encode=%.3f ms execute=%.3f ms\n",
                        pos0,
                        chunk,
                        il,
                        (t_encoded - t_layer0) * 1000.0,
                        (t_done - t_encoded) * 1000.0);
            }
            if (show_progress) {
                fprintf(stderr,
                        "ds4: gpu prefill token %u/%u layer %u/%u\r",
                        pos0 + chunk,
                        (uint32_t)prompt->len,
                        il + 1,
                        (uint32_t)DS4_N_LAYER);
                fflush(stderr);
            }
        }
        if (!ok) {
            if (ds4_gpu_synchronize() == 0) {
                fprintf(stderr, "ds4: Metal synchronize after chunked prefill failure also failed\n");
            }
            return false;
        }
        if (progress && !metal_graph_prefill_batch_row_logits(g, model, weights,
                                                              chunk - 1u,
                                                              logits))
        {
            return false;
        }
        if (progress) {
            progress(progress_ud, "prefill_chunk", (int)(pos0 + chunk), prompt->len);
        }
        pos0 += chunk;
    }
    if (show_progress) fputc('\n', stderr);
    if (last_chunk_tokens == 0) return false;

    const uint64_t hc_dim = (uint64_t)DS4_N_HC * DS4_N_EMBD;
    ds4_gpu_tensor *last_hc = metal_graph_tensor_row_view(g->batch_cur_hc,
                                                            last_chunk_tokens - 1u,
                                                            hc_dim);
    if (!last_hc) return false;
    ds4_gpu_tensor *saved_cur = g->cur_hc;
    g->cur_hc = last_hc;

    const double t_head0 = profile ? now_sec() : 0.0;
    bool ok = ds4_gpu_begin_commands() != 0;
    if (ok) ok = metal_graph_encode_output_head(g, model, weights, weights->output->dim[1]);
    const double t_head_encoded = profile ? now_sec() : 0.0;
    if (ok) ok = ds4_gpu_end_commands() != 0;
    const double t_head_done = 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｜>Review this excerpt for correctness risks, memory lifetime issues, and performance bottlenecks.

File: ds4.c

```c
;
            const double t_encoded = profile ? now_sec() : 0.0;
            if (ok) ok = ds4_gpu_end_commands() != 0;
            const double t_done = profile ? now_sec() : 0.0;
            if (ok && imatrix) ok = imatrix_collect_layer_batch(imatrix, g, il, chunk);
            if (profile) {
                encode_s += t_encoded - t_layer0;
                execute_s += t_done - t_encoded;
                fprintf(stderr,
                        "ds4: gpu chunked prefill pos=%u tokens=%u layer %u encode=%.3f ms execute=%.3f ms\n",
                        pos0,
                        chunk,
                        il,
                        (t_encoded - t_layer0) * 1000.0,
                        (t_done - t_encoded) * 1000.0);
            }
            if (show_progress) {
                fprintf(stderr,
                        "ds4: gpu prefill token %u/%u layer %u/%u\r",
                        pos0 + chunk,
                        (uint32_t)prompt->len,
                        il + 1,
                        (uint32_t)DS4_N_LAYER);
                fflush(stderr);
            }
        }
        if (!ok) {
            if (ds4_gpu_synchronize() == 0) {
                fprintf(stderr, "ds4: Metal synchronize after chunked prefill failure also failed\n");
            }
            return false;
        }
        if (progress && !metal_graph_prefill_batch_row_logits(g, model, weights,
                                                              chunk - 1u,
                                                              logits))
        {
            return false;
        }
        if (progress) {
            progress(progress_ud, "prefill_chunk", (int)(pos0 + chunk), prompt->len);
        }
        pos0 += chunk;
    }
    if (show_progress) fputc('\n', stderr);
    if (last_chunk_tokens == 0) return false;

    const uint64_t hc_dim = (uint64_t)DS4_N_HC * DS4_N_EMBD;
    ds4_gpu_tensor *last_hc = metal_graph_tensor_row_view(g->batch_cur_hc,
                                                            last_chunk_tokens - 1u,
                                                            hc_dim);
    if (!last_hc) return false;
    ds4_gpu_tensor *saved_cur = g->cur_hc;
    g->cur_hc = last_hc;

    const double t_head0 = profile ? now_sec() : 0.0;
    bool ok = ds4_gpu_begin_commands() != 0;
    if (ok) ok = metal_graph_encode_output_head(g, model, weights, weights->output->dim[1]);
    const double t_head_encoded = profile ? now_sec() : 0.0;
    if (ok) ok = ds4_gpu_end_commands() != 0;
    const double t_head_done = 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
;
            const double t_encoded = profile ? now_sec() : 0.0;
            if (ok) ok = ds4_gpu_end_commands() != 0;
            const double t_done = profile ? now_sec() : 0.0;
            if (ok && imatrix) ok = imatrix_collect_layer_batch(imatrix, g, il, chunk);
            if (profile) {
                encode_s += t_encoded - t_layer0;
                execute_s += t_done - t_encoded;
                fprintf(stderr,
                        "ds4: gpu chunked prefill pos=%u tokens=%u layer %u encode=%.3f ms execute=%.3f ms\n",
                        pos0,
                        chunk,
                        il,
                        (t_encoded - t_layer0) * 1000.0,
                        (t_done - t_encoded) * 1000.0);
            }
            if (show_progress) {
                fprintf(stderr,
                        "ds4: gpu prefill token %u/%u layer %u/%u\r",
                        pos0 + chunk,
                        (uint32_t)prompt->len,
                        il + 1,
                        (uint32_t)DS4_N_LAYER);
                fflush(stderr);
            }
        }
        if (!ok) {
            if (ds4_gpu_synchronize() == 0) {
                fprintf(stderr, "ds4: Metal synchronize after chunked prefill failure also failed\n");
            }
            return false;
        }
        if (progress && !metal_graph_prefill_batch_row_logits(g, model, weights,
                                                              chunk - 1u,
                                                              logits))
        {
            return false;
        }
        if (progress) {
            progress(progress_ud, "prefill_chunk", (int)(pos0 + chunk), prompt->len);
        }
        pos0 += chunk;
    }
    if (show_progress) fputc('\n', stderr);
    if (last_chunk_tokens == 0) return false;

    const uint64_t hc_dim = (uint64_t)DS4_N_HC * DS4_N_EMBD;
    ds4_gpu_tensor *last_hc = metal_graph_tensor_row_view(g->batch_cur_hc,
                                                            last_chunk_tokens - 1u,
                                                            hc_dim);
    if (!last_hc) return false;
    ds4_gpu_tensor *saved_cur = g->cur_hc;
    g->cur_hc = last_hc;

    const double t_head0 = profile ? now_sec() : 0.0;
    bool ok = ds4_gpu_begin_commands() != 0;
    if (ok) ok = metal_graph_encode_output_head(g, model, weights, weights->output->dim[1]);
    const double t_head_encoded = profile ? now_sec() : 0.0;
    if (ok) ok = ds4_gpu_end_commands() != 0;
    const double t_head_done = 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｜>Review this excerpt for correctness risks, memory lifetime issues, and performance bottlenecks.

File: ds4.c

```c
;
            const double t_encoded = profile ? now_sec() : 0.0;
            if (ok) ok = ds4_gpu_end_commands() != 0;
            const double t_done = profile ? now_sec() : 0.0;
            if (ok && imatrix) ok = imatrix_collect_layer_batch(imatrix, g, il, chunk);
            if (profile) {
                encode_s += t_encoded - t_layer0;
                execute_s += t_done - t_encoded;
                fprintf(stderr,
                        "ds4: gpu chunked prefill pos=%u tokens=%u layer %u encode=%.3f ms execute=%.3f ms\n",
                        pos0,
                        chunk,
                        il,
                        (t_encoded - t_layer0) * 1000.0,
                        (t_done - t_encoded) * 1000.0);
            }
            if (show_progress) {
                fprintf(stderr,
                        "ds4: gpu prefill token %u/%u layer %u/%u\r",
                        pos0 + chunk,
                        (uint32_t)prompt->len,
                        il + 1,
                        (uint32_t)DS4_N_LAYER);
                fflush(stderr);
            }
        }
        if (!ok) {
            if (ds4_gpu_synchronize() == 0) {
                fprintf(stderr, "ds4: Metal synchronize after chunked prefill failure also failed\n");
            }
            return false;
        }
        if (progress && !metal_graph_prefill_batch_row_logits(g, model, weights,
                                                              chunk - 1u,
                                                              logits))
        {
            return false;
        }
        if (progress) {
            progress(progress_ud, "prefill_chunk", (int)(pos0 + chunk), prompt->len);
        }
        pos0 += chunk;
    }
    if (show_progress) fputc('\n', stderr);
    if (last_chunk_tokens == 0) return false;

    const uint64_t hc_dim = (uint64_t)DS4_N_HC * DS4_N_EMBD;
    ds4_gpu_tensor *last_hc = metal_graph_tensor_row_view(g->batch_cur_hc,
                                                            last_chunk_tokens - 1u,
                                                            hc_dim);
    if (!last_hc) return false;
    ds4_gpu_tensor *saved_cur = g->cur_hc;
    g->cur_hc = last_hc;

    const double t_head0 = profile ? now_sec() : 0.0;
    bool ok = ds4_gpu_begin_commands() != 0;
    if (ok) ok = metal_graph_encode_output_head(g, model, weights, weights->output->dim[1]);
    const double t_head_encoded = profile ? now_sec() : 0.0;
    if (ok) ok = ds4_gpu_end_commands() != 0;
    const double t_head_done = 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]
Explain what this code does and identify the inference stage it belongs to.

File: ds4.c

```c
utput->dim[1]);
    const double t_head_encoded = profile ? now_sec() : 0.0;
    if (ok) ok = ds4_gpu_end_commands() != 0;
    const double t_head_done = profile ? now_sec() : 0.0;
    g->cur_hc = saved_cur;
    ds4_gpu_tensor_free(last_hc);
    if (!ok) return false;

    const double t_before_read = profile ? now_sec() : 0.0;
    if (logits) {
        ok = ds4_gpu_tensor_read(g->logits, 0, logits, (uint64_t)DS4_N_VOCAB * sizeof(float)) != 0;
    }
    if (profile) {
        const double t_read = now_sec();
        encode_s += t_head_encoded - t_head0;
        execute_s += t_head_done - t_head_encoded;
        fprintf(stderr,
                "ds4: gpu chunked prefill start=%u tokens=%u chunk=%u encode=%.3f ms execute=%.3f ms read=%.3f ms total=%.3f ms\n",
                start,
                n_tokens,
                chunk_cap,
                encode_s * 1000.0,
                execute_s * 1000.0,
                (t_read - t_before_read) * 1000.0,
                (t_read - t0) * 1000.0);
    }
    return ok;
}

/* Long prompts are prefetched in fixed-size chunks.  Chunks bound transient
 * attention buffers while preserving the same final KV/cache state. */
static bool metal_graph_prefill_chunked(
        ds4_gpu_graph *g,
        const ds4_model       *model,
        const ds4_weights     *weights,
        const token_vec       *prompt,
        int                    n_tokens,
        float                 *logits,
        bool                   show_progress,
        ds4_session_progress_fn progress,
        void                  *progress_ud) {
    if (n_tokens <= 0) return false;
    return metal_graph_prefill_chunked_range(g,
                                             model,
                                             weights,
                                             prompt,
                                             0,
                                             (uint32_t)n_tokens,
                                             logits,
                                             show_progress,
                                             progress,
                                             progress_ud,
                                             NULL);
}

/* Layer-major speculative target verifier for tiny MTP suffixes.
 *
 * This is the first production-shaped verifier attempt: unlike repeated decode
 * it runs the target model layer-by-layer for the whole speculative suffix, and
 * unlike the diagnostic path it does not read back full logits for every row.
```

<｜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
utput->dim[1]);
    const double t_head_encoded = profile ? now_sec() : 0.0;
    if (ok) ok = ds4_gpu_end_commands() != 0;
    const double t_head_done = profile ? now_sec() : 0.0;
    g->cur_hc = saved_cur;
    ds4_gpu_tensor_free(last_hc);
    if (!ok) return false;

    const double t_before_read = profile ? now_sec() : 0.0;
    if (logits) {
        ok = ds4_gpu_tensor_read(g->logits, 0, logits, (uint64_t)DS4_N_VOCAB * sizeof(float)) != 0;
    }
    if (profile) {
        const double t_read = now_sec();
        encode_s += t_head_encoded - t_head0;
        execute_s += t_head_done - t_head_encoded;
        fprintf(stderr,
                "ds4: gpu chunked prefill start=%u tokens=%u chunk=%u encode=%.3f ms execute=%.3f ms read=%.3f ms total=%.3f ms\n",
                start,
                n_tokens,
                chunk_cap,
                encode_s * 1000.0,
                execute_s * 1000.0,
                (t_read - t_before_read) * 1000.0,
                (t_read - t0) * 1000.0);
    }
    return ok;
}

/* Long prompts are prefetched in fixed-size chunks.  Chunks bound transient
 * attention buffers while preserving the same final KV/cache state. */
static bool metal_graph_prefill_chunked(
        ds4_gpu_graph *g,
        const ds4_model       *model,
        const ds4_weights     *weights,
        const token_vec       *prompt,
        int                    n_tokens,
        float                 *logits,
        bool                   show_progress,
        ds4_session_progress_fn progress,
        void                  *progress_ud) {
    if (n_tokens <= 0) return false;
    return metal_graph_prefill_chunked_range(g,
                                             model,
                                             weights,
                                             prompt,
                                             0,
                                             (uint32_t)n_tokens,
                                             logits,
                                             show_progress,
                                             progress,
                                             progress_ud,
                                             NULL);
}

/* Layer-major speculative target verifier for tiny MTP suffixes.
 *
 * This is the first production-shaped verifier attempt: unlike repeated decode
 * it runs the target model layer-by-layer for the whole speculative suffix, and
 * unlike the diagnostic path it does not read back full logits for every row.
```<｜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
utput->dim[1]);
    const double t_head_encoded = profile ? now_sec() : 0.0;
    if (ok) ok = ds4_gpu_end_commands() != 0;
    const double t_head_done = profile ? now_sec() : 0.0;
    g->cur_hc = saved_cur;
    ds4_gpu_tensor_free(last_hc);
    if (!ok) return false;

    const double t_before_read = profile ? now_sec() : 0.0;
    if (logits) {
        ok = ds4_gpu_tensor_read(g->logits, 0, logits, (uint64_t)DS4_N_VOCAB * sizeof(float)) != 0;
    }
    if (profile) {
        const double t_read = now_sec();
        encode_s += t_head_encoded - t_head0;
        execute_s += t_head_done - t_head_encoded;
        fprintf(stderr,
                "ds4: gpu chunked prefill start=%u tokens=%u chunk=%u encode=%.3f ms execute=%.3f ms read=%.3f ms total=%.3f ms\n",
                start,
                n_tokens,
                chunk_cap,
                encode_s * 1000.0,
                execute_s * 1000.0,
                (t_read - t_before_read) * 1000.0,
                (t_read - t0) * 1000.0);
    }
    return ok;
}

/* Long prompts are prefetched in fixed-size chunks.  Chunks bound transient
 * attention buffers while preserving the same final KV/cache state. */
static bool metal_graph_prefill_chunked(
        ds4_gpu_graph *g,
        const ds4_model       *model,
        const ds4_weights     *weights,
        const token_vec       *prompt,
        int                    n_tokens,
        float                 *logits,
        bool                   show_progress,
        ds4_session_progress_fn progress,
        void                  *progress_ud) {
    if (n_tokens <= 0) return false;
    return metal_graph_prefill_chunked_range(g,
                                             model,
                                             weights,
                                             prompt,
                                             0,
                                             (uint32_t)n_tokens,
                                             logits,
                                             show_progress,
                                             progress,
                                             progress_ud,
                                             NULL);
}

/* Layer-major speculative target verifier for tiny MTP suffixes.
 *
 * This is the first production-shaped verifier attempt: unlike repeated decode
 * it runs the target model layer-by-layer for the whole speculative suffix, and
 * unlike the diagnostic path it does not read back full logits for every row.
```

<｜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
utput->dim[1]);
    const double t_head_encoded = profile ? now_sec() : 0.0;
    if (ok) ok = ds4_gpu_end_commands() != 0;
    const double t_head_done = profile ? now_sec() : 0.0;
    g->cur_hc = saved_cur;
    ds4_gpu_tensor_free(last_hc);
    if (!ok) return false;

    const double t_before_read = profile ? now_sec() : 0.0;
    if (logits) {
        ok = ds4_gpu_tensor_read(g->logits, 0, logits, (uint64_t)DS4_N_VOCAB * sizeof(float)) != 0;
    }
    if (profile) {
        const double t_read = now_sec();
        encode_s += t_head_encoded - t_head0;
        execute_s += t_head_done - t_head_encoded;
        fprintf(stderr,
                "ds4: gpu chunked prefill start=%u tokens=%u chunk=%u encode=%.3f ms execute=%.3f ms read=%.3f ms total=%.3f ms\n",
                start,
                n_tokens,
                chunk_cap,
                encode_s * 1000.0,
                execute_s * 1000.0,
                (t_read - t_before_read) * 1000.0,
                (t_read - t0) * 1000.0);
    }
    return ok;
}

/* Long prompts are prefetched in fixed-size chunks.  Chunks bound transient
 * attention buffers while preserving the same final KV/cache state. */
static bool metal_graph_prefill_chunked(
        ds4_gpu_graph *g,
        const ds4_model       *model,
        const ds4_weights     *weights,
        const token_vec       *prompt,
        int                    n_tokens,
        float                 *logits,
        bool                   show_progress,
        ds4_session_progress_fn progress,
        void                  *progress_ud) {
    if (n_tokens <= 0) return false;
    return metal_graph_prefill_chunked_range(g,
                                             model,
                                             weights,
                                             prompt,
                                             0,
                                             (uint32_t)n_tokens,
                                             logits,
                                             show_progress,
                                             progress,
                                             progress_ud,
                                             NULL);
}

/* Layer-major speculative target verifier for tiny MTP suffixes.
 *
 * This is the first production-shaped verifier attempt: unlike repeated decode
 * it runs the target model layer-by-layer for the whole speculative suffix, and
 * unlike the diagnostic path it does not read back full logits for every row.
```<｜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
like repeated decode
 * it runs the target model layer-by-layer for the whole speculative suffix, and
 * unlike the diagnostic path it does not read back full logits for every row.
 * The verifier returns the row top-1 ids needed for acceptance.  The caller
 * then reads exactly one logits row: the row that becomes the new continuation
 * state.  It still reuses the existing batch layer kernels, so it is not yet
 * the final hand-written N=2/N=4 decode microbatch, but it exercises the right
 * verifier contract and removes the obvious diagnostic overheads first. */
static bool metal_graph_verify_suffix_tops(
        ds4_gpu_graph *g,
        const ds4_model       *model,
        const ds4_weights     *weights,
        const token_vec       *prompt,
        uint32_t               start,
        uint32_t               n_tokens,
        bool                   capture_prefix1,
        int                   *row_tops,
        float                 *row_logits) {
    if (n_tokens == 0 || n_tokens > g->prefill_cap || !g->spec_logits) return false;
    if (start > (uint32_t)prompt->len || n_tokens > (uint32_t)prompt->len - start) return false;
    const uint32_t top_rows = n_tokens > 1 ? n_tokens - 1 : 0;
    if (top_rows && !row_tops) return false;

    bool ok = metal_graph_upload_prompt_tokens(g->prefill_tokens, prompt, start, n_tokens);
    if (ok) ok = metal_graph_upload_prompt_embeddings_hc(g->batch_cur_hc,
                                                         g->prefill_tokens,
                                                         model,
                                                         weights,
                                                         prompt,
                                                         start,
                                                         n_tokens);
    if (!ok) return false;

    const bool saved_capture = g->spec_capture_prefix1;
    g->spec_capture_prefix1 = capture_prefix1 && n_tokens == 2;

    ok = ds4_gpu_begin_commands() != 0;
    for (uint32_t il = 0; ok && il < DS4_N_LAYER; il++) {
        ok = metal_graph_encode_layer_batch(g,
                                            model,
                                            &weights->layer[il],
                                            il,
                                            start,
                                            n_tokens);
    }
    if (ok) ok = ds4_gpu_end_commands() != 0;
    else (void)ds4_gpu_synchronize();
    g->spec_capture_prefix1 = saved_capture;
    if (!ok) return false;

    ok = ds4_gpu_begin_commands() != 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
like repeated decode
 * it runs the target model layer-by-layer for the whole speculative suffix, and
 * unlike the diagnostic path it does not read back full logits for every row.
 * The verifier returns the row top-1 ids needed for acceptance.  The caller
 * then reads exactly one logits row: the row that becomes the new continuation
 * state.  It still reuses the existing batch layer kernels, so it is not yet
 * the final hand-written N=2/N=4 decode microbatch, but it exercises the right
 * verifier contract and removes the obvious diagnostic overheads first. */
static bool metal_graph_verify_suffix_tops(
        ds4_gpu_graph *g,
        const ds4_model       *model,
        const ds4_weights     *weights,
        const token_vec       *prompt,
        uint32_t               start,
        uint32_t               n_tokens,
        bool                   capture_prefix1,
        int                   *row_tops,
        float                 *row_logits) {
    if (n_tokens == 0 || n_tokens > g->prefill_cap || !g->spec_logits) return false;
    if (start > (uint32_t)prompt->len || n_tokens > (uint32_t)prompt->len - start) return false;
    const uint32_t top_rows = n_tokens > 1 ? n_tokens - 1 : 0;
    if (top_rows && !row_tops) return false;

    bool ok = metal_graph_upload_prompt_tokens(g->prefill_tokens, prompt, start, n_tokens);
    if (ok) ok = metal_graph_upload_prompt_embeddings_hc(g->batch_cur_hc,
                                                         g->prefill_tokens,
                                                         model,
                                                         weights,
                                                         prompt,
                                                         start,
                                                         n_tokens);
    if (!ok) return false;

    const bool saved_capture = g->spec_capture_prefix1;
    g->spec_capture_prefix1 = capture_prefix1 && n_tokens == 2;

    ok = ds4_gpu_begin_commands() != 0;
    for (uint32_t il = 0; ok && il < DS4_N_LAYER; il++) {
        ok = metal_graph_encode_layer_batch(g,
                                            model,
                                            &weights->layer[il],
                                            il,
                                            start,
                                            n_tokens);
    }
    if (ok) ok = ds4_gpu_end_commands() != 0;
    else (void)ds4_gpu_synchronize();
    g->spec_capture_prefix1 = saved_capture;
    if (!ok) return false;

    ok = ds4_gpu_begin_commands() != 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
like repeated decode
 * it runs the target model layer-by-layer for the whole speculative suffix, and
 * unlike the diagnostic path it does not read back full logits for every row.
 * The verifier returns the row top-1 ids needed for acceptance.  The caller
 * then reads exactly one logits row: the row that becomes the new continuation
 * state.  It still reuses the existing batch layer kernels, so it is not yet
 * the final hand-written N=2/N=4 decode microbatch, but it exercises the right
 * verifier contract and removes the obvious diagnostic overheads first. */
static bool metal_graph_verify_suffix_tops(
        ds4_gpu_graph *g,
        const ds4_model       *model,
        const ds4_weights     *weights,
        const token_vec       *prompt,
        uint32_t               start,
        uint32_t               n_tokens,
        bool                   capture_prefix1,
        int                   *row_tops,
        float                 *row_logits) {
    if (n_tokens == 0 || n_tokens > g->prefill_cap || !g->spec_logits) return false;
    if (start > (uint32_t)prompt->len || n_tokens > (uint32_t)prompt->len - start) return false;
    const uint32_t top_rows = n_tokens > 1 ? n_tokens - 1 : 0;
    if (top_rows && !row_tops) return false;

    bool ok = metal_graph_upload_prompt_tokens(g->prefill_tokens, prompt, start, n_tokens);
    if (ok) ok = metal_graph_upload_prompt_embeddings_hc(g->batch_cur_hc,
                                                         g->prefill_tokens,
                                                         model,
                                                         weights,
                                                         prompt,
                                                         start,
                                                         n_tokens);
    if (!ok) return false;

    const bool saved_capture = g->spec_capture_prefix1;
    g->spec_capture_prefix1 = capture_prefix1 && n_tokens == 2;

    ok = ds4_gpu_begin_commands() != 0;
    for (uint32_t il = 0; ok && il < DS4_N_LAYER; il++) {
        ok = metal_graph_encode_layer_batch(g,
                                            model,
                                            &weights->layer[il],
                                            il,
                                            start,
                                            n_tokens);
    }
    if (ok) ok = ds4_gpu_end_commands() != 0;
    else (void)ds4_gpu_synchronize();
    g->spec_capture_prefix1 = saved_capture;
    if (!ok) return false;

    ok = ds4_gpu_begin_commands() != 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
like repeated decode
 * it runs the target model layer-by-layer for the whole speculative suffix, and
 * unlike the diagnostic path it does not read back full logits for every row.
 * The verifier returns the row top-1 ids needed for acceptance.  The caller
 * then reads exactly one logits row: the row that becomes the new continuation
 * state.  It still reuses the existing batch layer kernels, so it is not yet
 * the final hand-written N=2/N=4 decode microbatch, but it exercises the right
 * verifier contract and removes the obvious diagnostic overheads first. */
static bool metal_graph_verify_suffix_tops(
        ds4_gpu_graph *g,
        const ds4_model       *model,
        const ds4_weights     *weights,
        const token_vec       *prompt,
        uint32_t               start,
        uint32_t               n_tokens,
        bool                   capture_prefix1,
        int                   *row_tops,
        float                 *row_logits) {
    if (n_tokens == 0 || n_tokens > g->prefill_cap || !g->spec_logits) return false;
    if (start > (uint32_t)prompt->len || n_tokens > (uint32_t)prompt->len - start) return false;
    const uint32_t top_rows = n_tokens > 1 ? n_tokens - 1 : 0;
    if (top_rows && !row_tops) return false;

    bool ok = metal_graph_upload_prompt_tokens(g->prefill_tokens, prompt, start, n_tokens);
    if (ok) ok = metal_graph_upload_prompt_embeddings_hc(g->batch_cur_hc,
                                                         g->prefill_tokens,
                                                         model,
                                                         weights,
                                                         prompt,
                                                         start,
                                                         n_tokens);
    if (!ok) return false;

    const bool saved_capture = g->spec_capture_prefix1;
    g->spec_capture_prefix1 = capture_prefix1 && n_tokens == 2;

    ok = ds4_gpu_begin_commands() != 0;
    for (uint32_t il = 0; ok && il < DS4_N_LAYER; il++) {
        ok = metal_graph_encode_layer_batch(g,
                                            model,
                                            &weights->layer[il],
                                            il,
                                            start,
                                            n_tokens);
    }
    if (ok) ok = ds4_gpu_end_commands() != 0;
    else (void)ds4_gpu_synchronize();
    g->spec_capture_prefix1 = saved_capture;
    if (!ok) return false;

    ok = ds4_gpu_begin_commands() != 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
ds4_gpu_end_commands() != 0;
    else (void)ds4_gpu_synchronize();
    g->spec_capture_prefix1 = saved_capture;
    if (!ok) return false;

    ok = ds4_gpu_begin_commands() != 0;
    if (ok) ok = metal_graph_encode_output_head_batch(g,
                                                      model,
                                                      weights,
                                                      n_tokens,
                                                      weights->output->dim[1]);
    if (ok) {
        if (top_rows) {
            ok = ds4_gpu_indexer_topk_tensor(g->comp_selected,
                                               g->spec_logits,
                                               DS4_N_VOCAB,
                                               1,
                                               top_rows) != 0;
        }
    }
    if (ok) ok = ds4_gpu_end_commands() != 0;
    else (void)ds4_gpu_synchronize();
    if (ok && top_rows) {
        ok = ds4_gpu_tensor_read(g->comp_selected,
                                   0,
                                   row_tops,
                                   (uint64_t)top_rows * sizeof(row_tops[0])) != 0;
    }
    if (ok && row_logits) {
        ok = ds4_gpu_tensor_read(g->spec_logits,
                                   0,
                                   row_logits,
                                   (uint64_t)n_tokens * DS4_N_VOCAB * sizeof(row_logits[0])) != 0;
    }
    return ok;
}

static bool metal_graph_read_spec_logits_row(ds4_gpu_graph *g, uint32_t row, float *logits) {
    if (!g || !g->spec_logits || !logits || row >= g->prefill_cap) return false;
    const uint64_t row_bytes = (uint64_t)DS4_N_VOCAB * sizeof(float);
    return ds4_gpu_tensor_read(g->spec_logits,
                                 (uint64_t)row * row_bytes,
                                 logits,
                                 row_bytes) != 0;
}

/* Exact N=2 target verifier for MTP.
 *
 * The generic batch prefill path is fast, but it is not a safe substitute for
 * autoregressive decode: small row-wise differences in HC/MoE/output kernels
 * are enough to flip future greedy tokens.  This verifier keeps the exact
 * decode kernels and cache update order, but encodes the two proposed tokens
 * layer-by-layer in one command stream.  It returns the exact target top after
 * token0, and exact logits after token1. */
static bool metal_graph_verify_decode2_exact(
        ds4_gpu_graph *g,
        const ds4_model       *model,
        const ds4_weights     *weights,
        int                    token0,
```

<｜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
ds4_gpu_end_commands() != 0;
    else (void)ds4_gpu_synchronize();
    g->spec_capture_prefix1 = saved_capture;
    if (!ok) return false;

    ok = ds4_gpu_begin_commands() != 0;
    if (ok) ok = metal_graph_encode_output_head_batch(g,
                                                      model,
                                                      weights,
                                                      n_tokens,
                                                      weights->output->dim[1]);
    if (ok) {
        if (top_rows) {
            ok = ds4_gpu_indexer_topk_tensor(g->comp_selected,
                                               g->spec_logits,
                                               DS4_N_VOCAB,
                                               1,
                                               top_rows) != 0;
        }
    }
    if (ok) ok = ds4_gpu_end_commands() != 0;
    else (void)ds4_gpu_synchronize();
    if (ok && top_rows) {
        ok = ds4_gpu_tensor_read(g->comp_selected,
                                   0,
                                   row_tops,
                                   (uint64_t)top_rows * sizeof(row_tops[0])) != 0;
    }
    if (ok && row_logits) {
        ok = ds4_gpu_tensor_read(g->spec_logits,
                                   0,
                                   row_logits,
                                   (uint64_t)n_tokens * DS4_N_VOCAB * sizeof(row_logits[0])) != 0;
    }
    return ok;
}

static bool metal_graph_read_spec_logits_row(ds4_gpu_graph *g, uint32_t row, float *logits) {
    if (!g || !g->spec_logits || !logits || row >= g->prefill_cap) return false;
    const uint64_t row_bytes = (uint64_t)DS4_N_VOCAB * sizeof(float);
    return ds4_gpu_tensor_read(g->spec_logits,
                                 (uint64_t)row * row_bytes,
                                 logits,
                                 row_bytes) != 0;
}

/* Exact N=2 target verifier for MTP.
 *
 * The generic batch prefill path is fast, but it is not a safe substitute for
 * autoregressive decode: small row-wise differences in HC/MoE/output kernels
 * are enough to flip future greedy tokens.  This verifier keeps the exact
 * decode kernels and cache update order, but encodes the two proposed tokens
 * layer-by-layer in one command stream.  It returns the exact target top after
 * token0, and exact logits after token1. */
static bool metal_graph_verify_decode2_exact(
        ds4_gpu_graph *g,
        const ds4_model       *model,
        const ds4_weights     *weights,
        int                    token0,
```<｜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
ds4_gpu_end_commands() != 0;
    else (void)ds4_gpu_synchronize();
    g->spec_capture_prefix1 = saved_capture;
    if (!ok) return false;

    ok = ds4_gpu_begin_commands() != 0;
    if (ok) ok = metal_graph_encode_output_head_batch(g,
                                                      model,
                                                      weights,
                                                      n_tokens,
                                                      weights->output->dim[1]);
    if (ok) {
        if (top_rows) {
            ok = ds4_gpu_indexer_topk_tensor(g->comp_selected,
                                               g->spec_logits,
                                               DS4_N_VOCAB,
                                               1,
                                               top_rows) != 0;
        }
    }
    if (ok) ok = ds4_gpu_end_commands() != 0;
    else (void)ds4_gpu_synchronize();
    if (ok && top_rows) {
        ok = ds4_gpu_tensor_read(g->comp_selected,
                                   0,
                                   row_tops,
                                   (uint64_t)top_rows * sizeof(row_tops[0])) != 0;
    }
    if (ok && row_logits) {
        ok = ds4_gpu_tensor_read(g->spec_logits,
                                   0,
                                   row_logits,
                                   (uint64_t)n_tokens * DS4_N_VOCAB * sizeof(row_logits[0])) != 0;
    }
    return ok;
}

static bool metal_graph_read_spec_logits_row(ds4_gpu_graph *g, uint32_t row, float *logits) {
    if (!g || !g->spec_logits || !logits || row >= g->prefill_cap) return false;
    const uint64_t row_bytes = (uint64_t)DS4_N_VOCAB * sizeof(float);
    return ds4_gpu_tensor_read(g->spec_logits,
                                 (uint64_t)row * row_bytes,
                                 logits,
                                 row_bytes) != 0;
}

/* Exact N=2 target verifier for MTP.
 *
 * The generic batch prefill path is fast, but it is not a safe substitute for
 * autoregressive decode: small row-wise differences in HC/MoE/output kernels
 * are enough to flip future greedy tokens.  This verifier keeps the exact
 * decode kernels and cache update order, but encodes the two proposed tokens
 * layer-by-layer in one command stream.  It returns the exact target top after
 * token0, and exact logits after token1. */
static bool metal_graph_verify_decode2_exact(
        ds4_gpu_graph *g,
        const ds4_model       *model,
        const ds4_weights     *weights,
        int                    token0,
```

<｜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
ds4_gpu_end_commands() != 0;
    else (void)ds4_gpu_synchronize();
    g->spec_capture_prefix1 = saved_capture;
    if (!ok) return false;

    ok = ds4_gpu_begin_commands() != 0;
    if (ok) ok = metal_graph_encode_output_head_batch(g,
                                                      model,
                                                      weights,
                                                      n_tokens,
                                                      weights->output->dim[1]);
    if (ok) {
        if (top_rows) {
            ok = ds4_gpu_indexer_topk_tensor(g->comp_selected,
                                               g->spec_logits,
                                               DS4_N_VOCAB,
                                               1,
                                               top_rows) != 0;
        }
    }
    if (ok) ok = ds4_gpu_end_commands() != 0;
    else (void)ds4_gpu_synchronize();
    if (ok && top_rows) {
        ok = ds4_gpu_tensor_read(g->comp_selected,
                                   0,
                                   row_tops,
                                   (uint64_t)top_rows * sizeof(row_tops[0])) != 0;
    }
    if (ok && row_logits) {
        ok = ds4_gpu_tensor_read(g->spec_logits,
                                   0,
                                   row_logits,
                                   (uint64_t)n_tokens * DS4_N_VOCAB * sizeof(row_logits[0])) != 0;
    }
    return ok;
}

static bool metal_graph_read_spec_logits_row(ds4_gpu_graph *g, uint32_t row, float *logits) {
    if (!g || !g->spec_logits || !logits || row >= g->prefill_cap) return false;
    const uint64_t row_bytes = (uint64_t)DS4_N_VOCAB * sizeof(float);
    return ds4_gpu_tensor_read(g->spec_logits,
                                 (uint64_t)row * row_bytes,
                                 logits,
                                 row_bytes) != 0;
}

/* Exact N=2 target verifier for MTP.
 *
 * The generic batch prefill path is fast, but it is not a safe substitute for
 * autoregressive decode: small row-wise differences in HC/MoE/output kernels
 * are enough to flip future greedy tokens.  This verifier keeps the exact
 * decode kernels and cache update order, but encodes the two proposed tokens
 * layer-by-layer in one command stream.  It returns the exact target top after
 * token0, and exact logits after token1. */
static bool metal_graph_verify_decode2_exact(
        ds4_gpu_graph *g,
        const ds4_model       *model,
        const ds4_weights     *weights,
        int                    token0,
```<｜Assistant｜><think>