[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
es described by GGUF: ");
    print_size(tensor_bytes);
    printf("\n");
    printf("logical parameters: %.2f B\n", (double)params / 1000000000.0);

    printf("tensor types:\n");
    for (uint32_t type = 0; type < sizeof(gguf_types)/sizeof(gguf_types[0]); type++) {
        uint64_t count = 0;
        uint64_t bytes = 0;
        for (uint64_t i = 0; i < m->n_tensors; i++) {
            if (m->tensors[i].type == type) {
                count++;
                bytes += m->tensors[i].bytes;
            }
        }
        if (count != 0) {
            printf("  %-8s %5" PRIu64 " tensors, ", tensor_type_name(type), count);
            print_size(bytes);
            printf("\n");
        }
    }

}

static ds4_tensor *model_find_tensor(const ds4_model *m, const char *name) {
    const size_t len = strlen(name);
    for (uint64_t i = 0; i < m->n_tensors; i++) {
        if (m->tensors[i].name.len == len &&
            memcmp(m->tensors[i].name.ptr, name, len) == 0) {
            return &m->tensors[i];
        }
    }
    return NULL;
}

#ifndef DS4_NO_GPU
#ifndef __APPLE__
typedef struct {
    uint64_t off;
    uint64_t end;
} accelerator_tensor_span;

static int accelerator_tensor_span_cmp(const void *a, const void *b) {
    const accelerator_tensor_span *sa = a;
    const accelerator_tensor_span *sb = b;
    if (sa->off < sb->off) return -1;
    if (sa->off > sb->off) return 1;
    if (sa->end < sb->end) return -1;
    if (sa->end > sb->end) return 1;
    return 0;
}

static uint64_t accelerator_cuda_preload_span_bytes(void) {
    uint64_t mb = 1024;
    const char *env = getenv("DS4_CUDA_WEIGHT_PRELOAD_SPAN_MB");
    if (env && env[0]) {
        char *end = NULL;
        unsigned long long v = strtoull(env, &end, 10);
        if (end != env && v > 0) mb = (uint64_t)v;
    }
    if (mb < 64) mb = 64;
    if (mb > 4096) mb = 4096;
    return mb * 1048576ull;
}

static bool accelerator_cache_model_tensor_spans(const ds4_model *m, uint64_t *cached_out) {
    accelerator_tensor_span *spans = xmalloc((size_t)m->n_tensors * sizeof(spans[0]));
    uint64_t nspan = 0;
    for (uint64_t i = 0; i < m->n_tensors; i++) {
        const ds4_tensor *t = &m->tensors[i];
        if (t->bytes == 0) continue;
        if (t->abs_offset > m->size || t->bytes > m->size - t->abs_offset) {
            free(spans);
            return false;
        }
        spans[nspan++] = (accelerator_tensor_span){
            .off = t->abs_offset,
            .end = t->abs_offset + t->bytes,
        };
    }
    qsort(spans, (size_t)nspan, sizeof(spans[0]), accelerator_tensor_span_cmp);
```

<｜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
es described by GGUF: ");
    print_size(tensor_bytes);
    printf("\n");
    printf("logical parameters: %.2f B\n", (double)params / 1000000000.0);

    printf("tensor types:\n");
    for (uint32_t type = 0; type < sizeof(gguf_types)/sizeof(gguf_types[0]); type++) {
        uint64_t count = 0;
        uint64_t bytes = 0;
        for (uint64_t i = 0; i < m->n_tensors; i++) {
            if (m->tensors[i].type == type) {
                count++;
                bytes += m->tensors[i].bytes;
            }
        }
        if (count != 0) {
            printf("  %-8s %5" PRIu64 " tensors, ", tensor_type_name(type), count);
            print_size(bytes);
            printf("\n");
        }
    }

}

static ds4_tensor *model_find_tensor(const ds4_model *m, const char *name) {
    const size_t len = strlen(name);
    for (uint64_t i = 0; i < m->n_tensors; i++) {
        if (m->tensors[i].name.len == len &&
            memcmp(m->tensors[i].name.ptr, name, len) == 0) {
            return &m->tensors[i];
        }
    }
    return NULL;
}

#ifndef DS4_NO_GPU
#ifndef __APPLE__
typedef struct {
    uint64_t off;
    uint64_t end;
} accelerator_tensor_span;

static int accelerator_tensor_span_cmp(const void *a, const void *b) {
    const accelerator_tensor_span *sa = a;
    const accelerator_tensor_span *sb = b;
    if (sa->off < sb->off) return -1;
    if (sa->off > sb->off) return 1;
    if (sa->end < sb->end) return -1;
    if (sa->end > sb->end) return 1;
    return 0;
}

static uint64_t accelerator_cuda_preload_span_bytes(void) {
    uint64_t mb = 1024;
    const char *env = getenv("DS4_CUDA_WEIGHT_PRELOAD_SPAN_MB");
    if (env && env[0]) {
        char *end = NULL;
        unsigned long long v = strtoull(env, &end, 10);
        if (end != env && v > 0) mb = (uint64_t)v;
    }
    if (mb < 64) mb = 64;
    if (mb > 4096) mb = 4096;
    return mb * 1048576ull;
}

static bool accelerator_cache_model_tensor_spans(const ds4_model *m, uint64_t *cached_out) {
    accelerator_tensor_span *spans = xmalloc((size_t)m->n_tensors * sizeof(spans[0]));
    uint64_t nspan = 0;
    for (uint64_t i = 0; i < m->n_tensors; i++) {
        const ds4_tensor *t = &m->tensors[i];
        if (t->bytes == 0) continue;
        if (t->abs_offset > m->size || t->bytes > m->size - t->abs_offset) {
            free(spans);
            return false;
        }
        spans[nspan++] = (accelerator_tensor_span){
            .off = t->abs_offset,
            .end = t->abs_offset + t->bytes,
        };
    }
    qsort(spans, (size_t)nspan, sizeof(spans[0]), accelerator_tensor_span_cmp);
```<｜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
model->map,
                                                     model->size,
                                                     weights->token_embd->abs_offset,
                                                     (uint32_t)weights->token_embd->dim[1],
                                                     (uint32_t)token,
                                                     DS4_N_EMBD,
                                                     DS4_N_HC) != 0;

        for (uint32_t il = 0; ok && il < DS4_N_LAYER; il++) {
            ok = metal_graph_encode_decode_layer(&g, model, &weights->layer[il],
                                                 il, 0, g.layer_raw_cache[il],
                                                 g.raw_cap, 0, 1, token);
            ds4_gpu_tensor *tmp = g.cur_hc;
            g.cur_hc = g.after_ffn_hc;
            g.after_ffn_hc = tmp;
        }

        if (ok) ok = metal_graph_encode_output_head(&g, model, weights, vocab_dim);
        if (ok) ok = ds4_gpu_end_commands() != 0;
    }

    if (ok) {
        ok = ds4_gpu_tensor_read(g.cur_hc, 0, gpu_hc, hc_dim * sizeof(float)) != 0 &&
             ds4_gpu_tensor_read(g.logits, 0, gpu_logits, vocab_dim * sizeof(float)) != 0;
    }

    if (ok) {
        const uint64_t cpu_top = argmax_f32(cpu_logits, vocab_dim);
        const uint64_t gpu_top = argmax_f32(gpu_logits, vocab_dim);
        fprintf(stderr,
                "ds4: Metal full first-token graph diffs: final_hc_max=%g final_hc_rms=%g logits_max=%g logits_rms=%g cpu_top=%llu gpu_top=%llu cpu_top_logit=%g gpu_top_logit=%g\n",
                max_abs_diff(cpu_hc, gpu_hc, hc_dim),
                rms_abs_diff(cpu_hc, gpu_hc, hc_dim),
                max_abs_diff(cpu_logits, gpu_logits, vocab_dim),
                rms_abs_diff(cpu_logits, gpu_logits, vocab_dim),
                (unsigned long long)cpu_top,
                (unsigned long long)gpu_top,
                cpu_logits[cpu_top],
                gpu_logits[gpu_top]);
    } else {
        fprintf(stderr, "ds4: Metal full first-token graph test failed\n");
        if (ds4_gpu_synchronize() == 0) {
            fprintf(stderr, "ds4: Metal synchronize after full graph failure also failed\n");
        }
    }

    metal_graph_free(&g);
    free(gpu_logits);
    free(cpu_logits);
    free(gpu_hc);
    free(cpu_hc);
    return ok ? 0 : 1;
}

/* =========================================================================
 * Metal Release Decode and Prefill.
 * =========================================================================
 *
```

<｜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
model->map,
                                                     model->size,
                                                     weights->token_embd->abs_offset,
                                                     (uint32_t)weights->token_embd->dim[1],
                                                     (uint32_t)token,
                                                     DS4_N_EMBD,
                                                     DS4_N_HC) != 0;

        for (uint32_t il = 0; ok && il < DS4_N_LAYER; il++) {
            ok = metal_graph_encode_decode_layer(&g, model, &weights->layer[il],
                                                 il, 0, g.layer_raw_cache[il],
                                                 g.raw_cap, 0, 1, token);
            ds4_gpu_tensor *tmp = g.cur_hc;
            g.cur_hc = g.after_ffn_hc;
            g.after_ffn_hc = tmp;
        }

        if (ok) ok = metal_graph_encode_output_head(&g, model, weights, vocab_dim);
        if (ok) ok = ds4_gpu_end_commands() != 0;
    }

    if (ok) {
        ok = ds4_gpu_tensor_read(g.cur_hc, 0, gpu_hc, hc_dim * sizeof(float)) != 0 &&
             ds4_gpu_tensor_read(g.logits, 0, gpu_logits, vocab_dim * sizeof(float)) != 0;
    }

    if (ok) {
        const uint64_t cpu_top = argmax_f32(cpu_logits, vocab_dim);
        const uint64_t gpu_top = argmax_f32(gpu_logits, vocab_dim);
        fprintf(stderr,
                "ds4: Metal full first-token graph diffs: final_hc_max=%g final_hc_rms=%g logits_max=%g logits_rms=%g cpu_top=%llu gpu_top=%llu cpu_top_logit=%g gpu_top_logit=%g\n",
                max_abs_diff(cpu_hc, gpu_hc, hc_dim),
                rms_abs_diff(cpu_hc, gpu_hc, hc_dim),
                max_abs_diff(cpu_logits, gpu_logits, vocab_dim),
                rms_abs_diff(cpu_logits, gpu_logits, vocab_dim),
                (unsigned long long)cpu_top,
                (unsigned long long)gpu_top,
                cpu_logits[cpu_top],
                gpu_logits[gpu_top]);
    } else {
        fprintf(stderr, "ds4: Metal full first-token graph test failed\n");
        if (ds4_gpu_synchronize() == 0) {
            fprintf(stderr, "ds4: Metal synchronize after full graph failure also failed\n");
        }
    }

    metal_graph_free(&g);
    free(gpu_logits);
    free(cpu_logits);
    free(gpu_hc);
    free(cpu_hc);
    return ok ? 0 : 1;
}

/* =========================================================================
 * Metal Release Decode and Prefill.
 * =========================================================================
 *
```<｜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
model->map,
                                                     model->size,
                                                     weights->token_embd->abs_offset,
                                                     (uint32_t)weights->token_embd->dim[1],
                                                     (uint32_t)token,
                                                     DS4_N_EMBD,
                                                     DS4_N_HC) != 0;

        for (uint32_t il = 0; ok && il < DS4_N_LAYER; il++) {
            ok = metal_graph_encode_decode_layer(&g, model, &weights->layer[il],
                                                 il, 0, g.layer_raw_cache[il],
                                                 g.raw_cap, 0, 1, token);
            ds4_gpu_tensor *tmp = g.cur_hc;
            g.cur_hc = g.after_ffn_hc;
            g.after_ffn_hc = tmp;
        }

        if (ok) ok = metal_graph_encode_output_head(&g, model, weights, vocab_dim);
        if (ok) ok = ds4_gpu_end_commands() != 0;
    }

    if (ok) {
        ok = ds4_gpu_tensor_read(g.cur_hc, 0, gpu_hc, hc_dim * sizeof(float)) != 0 &&
             ds4_gpu_tensor_read(g.logits, 0, gpu_logits, vocab_dim * sizeof(float)) != 0;
    }

    if (ok) {
        const uint64_t cpu_top = argmax_f32(cpu_logits, vocab_dim);
        const uint64_t gpu_top = argmax_f32(gpu_logits, vocab_dim);
        fprintf(stderr,
                "ds4: Metal full first-token graph diffs: final_hc_max=%g final_hc_rms=%g logits_max=%g logits_rms=%g cpu_top=%llu gpu_top=%llu cpu_top_logit=%g gpu_top_logit=%g\n",
                max_abs_diff(cpu_hc, gpu_hc, hc_dim),
                rms_abs_diff(cpu_hc, gpu_hc, hc_dim),
                max_abs_diff(cpu_logits, gpu_logits, vocab_dim),
                rms_abs_diff(cpu_logits, gpu_logits, vocab_dim),
                (unsigned long long)cpu_top,
                (unsigned long long)gpu_top,
                cpu_logits[cpu_top],
                gpu_logits[gpu_top]);
    } else {
        fprintf(stderr, "ds4: Metal full first-token graph test failed\n");
        if (ds4_gpu_synchronize() == 0) {
            fprintf(stderr, "ds4: Metal synchronize after full graph failure also failed\n");
        }
    }

    metal_graph_free(&g);
    free(gpu_logits);
    free(cpu_logits);
    free(gpu_hc);
    free(cpu_hc);
    return ok ? 0 : 1;
}

/* =========================================================================
 * Metal Release Decode and Prefill.
 * =========================================================================
 *
```

<｜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
model->map,
                                                     model->size,
                                                     weights->token_embd->abs_offset,
                                                     (uint32_t)weights->token_embd->dim[1],
                                                     (uint32_t)token,
                                                     DS4_N_EMBD,
                                                     DS4_N_HC) != 0;

        for (uint32_t il = 0; ok && il < DS4_N_LAYER; il++) {
            ok = metal_graph_encode_decode_layer(&g, model, &weights->layer[il],
                                                 il, 0, g.layer_raw_cache[il],
                                                 g.raw_cap, 0, 1, token);
            ds4_gpu_tensor *tmp = g.cur_hc;
            g.cur_hc = g.after_ffn_hc;
            g.after_ffn_hc = tmp;
        }

        if (ok) ok = metal_graph_encode_output_head(&g, model, weights, vocab_dim);
        if (ok) ok = ds4_gpu_end_commands() != 0;
    }

    if (ok) {
        ok = ds4_gpu_tensor_read(g.cur_hc, 0, gpu_hc, hc_dim * sizeof(float)) != 0 &&
             ds4_gpu_tensor_read(g.logits, 0, gpu_logits, vocab_dim * sizeof(float)) != 0;
    }

    if (ok) {
        const uint64_t cpu_top = argmax_f32(cpu_logits, vocab_dim);
        const uint64_t gpu_top = argmax_f32(gpu_logits, vocab_dim);
        fprintf(stderr,
                "ds4: Metal full first-token graph diffs: final_hc_max=%g final_hc_rms=%g logits_max=%g logits_rms=%g cpu_top=%llu gpu_top=%llu cpu_top_logit=%g gpu_top_logit=%g\n",
                max_abs_diff(cpu_hc, gpu_hc, hc_dim),
                rms_abs_diff(cpu_hc, gpu_hc, hc_dim),
                max_abs_diff(cpu_logits, gpu_logits, vocab_dim),
                rms_abs_diff(cpu_logits, gpu_logits, vocab_dim),
                (unsigned long long)cpu_top,
                (unsigned long long)gpu_top,
                cpu_logits[cpu_top],
                gpu_logits[gpu_top]);
    } else {
        fprintf(stderr, "ds4: Metal full first-token graph test failed\n");
        if (ds4_gpu_synchronize() == 0) {
            fprintf(stderr, "ds4: Metal synchronize after full graph failure also failed\n");
        }
    }

    metal_graph_free(&g);
    free(gpu_logits);
    free(cpu_logits);
    free(gpu_hc);
    free(cpu_hc);
    return ok ? 0 : 1;
}

/* =========================================================================
 * Metal Release Decode and Prefill.
 * =========================================================================
 *
```<｜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
===============================================================
 * Metal Release Decode and Prefill.
 * =========================================================================
 *
 * Everything below is the user-facing Metal backend.  It uses the same layer
 * encoder as diagnostics, but diagnostics are not required for normal command
 * flow and their CPU reads stay outside these generation entry points.
 */

/* Encode a full single-token decode step on Metal.  This is the generation
 * hot path: update caches, run all layers, then produce logits. */
static bool metal_graph_encode_token_raw_swa(
        ds4_gpu_graph *g,
        const ds4_model       *model,
        const ds4_weights     *weights,
        int                    token,
        uint32_t               pos,
        bool                   need_logits,
        bool                   allow_split_flush) {
    if (g->raw_cap == 0) {
        fprintf(stderr, "ds4: Metal graph raw KV cache is not allocated\n");
        return false;
    }
    const uint32_t raw_row = pos % g->raw_cap;
    const uint32_t n_raw = metal_graph_raw_span_for_batch(g, pos, 1);

    bool ok = ds4_gpu_embed_token_hc_tensor(g->cur_hc,
                                              model->map,
                                              model->size,
                                              weights->token_embd->abs_offset,
                                              (uint32_t)weights->token_embd->dim[1],
                                              (uint32_t)token,
                                              DS4_N_EMBD,
                                              DS4_N_HC) != 0;

    /*
     * Start executing the prefix of the decode graph while the CPU is still
     * encoding the rest. The split point is layer-based because this executor is
     * a fixed DS4 tape, not a dynamic node graph; four layers is the measured
     * point where the prefix is large enough to hide useful work without
     * starving the second command buffer.
     */
    uint32_t split_after_layers = 4;
    const char *split_env = getenv("DS4_METAL_GRAPH_TOKEN_SPLIT_LAYERS");
    if (split_env && split_env[0]) {
        char *end = NULL;
        unsigned long v = strtoul(split_env, &end, 10);
        if (end != split_env && v <= DS4_N_LAYER) split_after_layers = (uint32_t)v;
    }

    for (uint32_t il = 0; ok && il < DS4_N_LAYER; il++) {
        ok = metal_graph_encode_decode_layer(g,
                                             model,
                                             &weights->layer[il],
```

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

File: ds4.c

```c
===============================================================
 * Metal Release Decode and Prefill.
 * =========================================================================
 *
 * Everything below is the user-facing Metal backend.  It uses the same layer
 * encoder as diagnostics, but diagnostics are not required for normal command
 * flow and their CPU reads stay outside these generation entry points.
 */

/* Encode a full single-token decode step on Metal.  This is the generation
 * hot path: update caches, run all layers, then produce logits. */
static bool metal_graph_encode_token_raw_swa(
        ds4_gpu_graph *g,
        const ds4_model       *model,
        const ds4_weights     *weights,
        int                    token,
        uint32_t               pos,
        bool                   need_logits,
        bool                   allow_split_flush) {
    if (g->raw_cap == 0) {
        fprintf(stderr, "ds4: Metal graph raw KV cache is not allocated\n");
        return false;
    }
    const uint32_t raw_row = pos % g->raw_cap;
    const uint32_t n_raw = metal_graph_raw_span_for_batch(g, pos, 1);

    bool ok = ds4_gpu_embed_token_hc_tensor(g->cur_hc,
                                              model->map,
                                              model->size,
                                              weights->token_embd->abs_offset,
                                              (uint32_t)weights->token_embd->dim[1],
                                              (uint32_t)token,
                                              DS4_N_EMBD,
                                              DS4_N_HC) != 0;

    /*
     * Start executing the prefix of the decode graph while the CPU is still
     * encoding the rest. The split point is layer-based because this executor is
     * a fixed DS4 tape, not a dynamic node graph; four layers is the measured
     * point where the prefix is large enough to hide useful work without
     * starving the second command buffer.
     */
    uint32_t split_after_layers = 4;
    const char *split_env = getenv("DS4_METAL_GRAPH_TOKEN_SPLIT_LAYERS");
    if (split_env && split_env[0]) {
        char *end = NULL;
        unsigned long v = strtoul(split_env, &end, 10);
        if (end != split_env && v <= DS4_N_LAYER) split_after_layers = (uint32_t)v;
    }

    for (uint32_t il = 0; ok && il < DS4_N_LAYER; il++) {
        ok = metal_graph_encode_decode_layer(g,
                                             model,
                                             &weights->layer[il],
```<｜Assistant｜></think>


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

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

File: ds4.c

```c
===============================================================
 * Metal Release Decode and Prefill.
 * =========================================================================
 *
 * Everything below is the user-facing Metal backend.  It uses the same layer
 * encoder as diagnostics, but diagnostics are not required for normal command
 * flow and their CPU reads stay outside these generation entry points.
 */

/* Encode a full single-token decode step on Metal.  This is the generation
 * hot path: update caches, run all layers, then produce logits. */
static bool metal_graph_encode_token_raw_swa(
        ds4_gpu_graph *g,
        const ds4_model       *model,
        const ds4_weights     *weights,
        int                    token,
        uint32_t               pos,
        bool                   need_logits,
        bool                   allow_split_flush) {
    if (g->raw_cap == 0) {
        fprintf(stderr, "ds4: Metal graph raw KV cache is not allocated\n");
        return false;
    }
    const uint32_t raw_row = pos % g->raw_cap;
    const uint32_t n_raw = metal_graph_raw_span_for_batch(g, pos, 1);

    bool ok = ds4_gpu_embed_token_hc_tensor(g->cur_hc,
                                              model->map,
                                              model->size,
                                              weights->token_embd->abs_offset,
                                              (uint32_t)weights->token_embd->dim[1],
                                              (uint32_t)token,
                                              DS4_N_EMBD,
                                              DS4_N_HC) != 0;

    /*
     * Start executing the prefix of the decode graph while the CPU is still
     * encoding the rest. The split point is layer-based because this executor is
     * a fixed DS4 tape, not a dynamic node graph; four layers is the measured
     * point where the prefix is large enough to hide useful work without
     * starving the second command buffer.
     */
    uint32_t split_after_layers = 4;
    const char *split_env = getenv("DS4_METAL_GRAPH_TOKEN_SPLIT_LAYERS");
    if (split_env && split_env[0]) {
        char *end = NULL;
        unsigned long v = strtoul(split_env, &end, 10);
        if (end != split_env && v <= DS4_N_LAYER) split_after_layers = (uint32_t)v;
    }

    for (uint32_t il = 0; ok && il < DS4_N_LAYER; il++) {
        ok = metal_graph_encode_decode_layer(g,
                                             model,
                                             &weights->layer[il],
```

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

File: ds4.c

```c
===============================================================
 * Metal Release Decode and Prefill.
 * =========================================================================
 *
 * Everything below is the user-facing Metal backend.  It uses the same layer
 * encoder as diagnostics, but diagnostics are not required for normal command
 * flow and their CPU reads stay outside these generation entry points.
 */

/* Encode a full single-token decode step on Metal.  This is the generation
 * hot path: update caches, run all layers, then produce logits. */
static bool metal_graph_encode_token_raw_swa(
        ds4_gpu_graph *g,
        const ds4_model       *model,
        const ds4_weights     *weights,
        int                    token,
        uint32_t               pos,
        bool                   need_logits,
        bool                   allow_split_flush) {
    if (g->raw_cap == 0) {
        fprintf(stderr, "ds4: Metal graph raw KV cache is not allocated\n");
        return false;
    }
    const uint32_t raw_row = pos % g->raw_cap;
    const uint32_t n_raw = metal_graph_raw_span_for_batch(g, pos, 1);

    bool ok = ds4_gpu_embed_token_hc_tensor(g->cur_hc,
                                              model->map,
                                              model->size,
                                              weights->token_embd->abs_offset,
                                              (uint32_t)weights->token_embd->dim[1],
                                              (uint32_t)token,
                                              DS4_N_EMBD,
                                              DS4_N_HC) != 0;

    /*
     * Start executing the prefix of the decode graph while the CPU is still
     * encoding the rest. The split point is layer-based because this executor is
     * a fixed DS4 tape, not a dynamic node graph; four layers is the measured
     * point where the prefix is large enough to hide useful work without
     * starving the second command buffer.
     */
    uint32_t split_after_layers = 4;
    const char *split_env = getenv("DS4_METAL_GRAPH_TOKEN_SPLIT_LAYERS");
    if (split_env && split_env[0]) {
        char *end = NULL;
        unsigned long v = strtoul(split_env, &end, 10);
        if (end != split_env && v <= DS4_N_LAYER) split_after_layers = (uint32_t)v;
    }

    for (uint32_t il = 0; ok && il < DS4_N_LAYER; il++) {
        ok = metal_graph_encode_decode_layer(g,
                                             model,
                                             &weights->layer[il],
```<｜Assistant｜><think>


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

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

File: ds4.c

```c
LAYER; il++) {
        ok = metal_graph_encode_decode_layer(g,
                                             model,
                                             &weights->layer[il],
                                             il,
                                             pos,
                                             g->layer_raw_cache[il],
                                             g->raw_cap,
                                             raw_row,
                                             n_raw,
                                             token);
        ds4_gpu_tensor *tmp = g->cur_hc;
        g->cur_hc = g->after_ffn_hc;
        g->after_ffn_hc = tmp;
        if (ok && allow_split_flush && split_after_layers != 0 && il + 1u == split_after_layers) {
            ok = ds4_gpu_flush_commands() != 0;
        }
    }

    if (ok && need_logits) {
        ok = metal_graph_encode_output_head(g, model, weights, weights->output->dim[1]);
    }
    return ok;
}

static ds4_gpu_tensor *metal_graph_tensor_row_view(
        ds4_gpu_tensor *base,
        uint32_t          row,
        uint64_t          row_values) {
    return ds4_gpu_tensor_view(base,
                                 (uint64_t)row * row_values * sizeof(float),
                                 row_values * sizeof(float));
}

/* Upload prompt token ids for kernels that need token-aware hash routing. */
static bool metal_graph_upload_prompt_tokens(
        ds4_gpu_tensor *out_tokens,
        const token_vec  *prompt,
        uint32_t          pos0,
        uint32_t          n_tokens) {
    if (!out_tokens || pos0 > (uint32_t)prompt->len || n_tokens > (uint32_t)prompt->len - pos0) {
        return false;
    }

    int32_t *tokens = xmalloc((size_t)n_tokens * sizeof(tokens[0]));
    for (uint32_t i = 0; i < n_tokens; i++) tokens[i] = prompt->v[pos0 + i];

    const bool ok = ds4_gpu_tensor_write(out_tokens,
                                           0,
                                           tokens,
                                           (uint64_t)n_tokens * sizeof(tokens[0])) != 0;
    free(tokens);
    return ok;
}

/* Rebuild ratio-4 compressor state after chunked prefill so a following decode
 * token sees the same rolling compression window. */
static bool metal_graph_refresh_ratio4_compressor_state(
        ds4_gpu_graph  *g,
        const ds4_model  *model,
        ds4_gpu_tensor *state_kv,
        ds4_gpu_tensor *state_score,
        const ds4_tensor *kv_weight,
        const ds4_tensor *score_weight,
        const ds4_tensor *ape,
        uint32_t          head_dim,
```

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

File: ds4.c

```c
LAYER; il++) {
        ok = metal_graph_encode_decode_layer(g,
                                             model,
                                             &weights->layer[il],
                                             il,
                                             pos,
                                             g->layer_raw_cache[il],
                                             g->raw_cap,
                                             raw_row,
                                             n_raw,
                                             token);
        ds4_gpu_tensor *tmp = g->cur_hc;
        g->cur_hc = g->after_ffn_hc;
        g->after_ffn_hc = tmp;
        if (ok && allow_split_flush && split_after_layers != 0 && il + 1u == split_after_layers) {
            ok = ds4_gpu_flush_commands() != 0;
        }
    }

    if (ok && need_logits) {
        ok = metal_graph_encode_output_head(g, model, weights, weights->output->dim[1]);
    }
    return ok;
}

static ds4_gpu_tensor *metal_graph_tensor_row_view(
        ds4_gpu_tensor *base,
        uint32_t          row,
        uint64_t          row_values) {
    return ds4_gpu_tensor_view(base,
                                 (uint64_t)row * row_values * sizeof(float),
                                 row_values * sizeof(float));
}

/* Upload prompt token ids for kernels that need token-aware hash routing. */
static bool metal_graph_upload_prompt_tokens(
        ds4_gpu_tensor *out_tokens,
        const token_vec  *prompt,
        uint32_t          pos0,
        uint32_t          n_tokens) {
    if (!out_tokens || pos0 > (uint32_t)prompt->len || n_tokens > (uint32_t)prompt->len - pos0) {
        return false;
    }

    int32_t *tokens = xmalloc((size_t)n_tokens * sizeof(tokens[0]));
    for (uint32_t i = 0; i < n_tokens; i++) tokens[i] = prompt->v[pos0 + i];

    const bool ok = ds4_gpu_tensor_write(out_tokens,
                                           0,
                                           tokens,
                                           (uint64_t)n_tokens * sizeof(tokens[0])) != 0;
    free(tokens);
    return ok;
}

/* Rebuild ratio-4 compressor state after chunked prefill so a following decode
 * token sees the same rolling compression window. */
static bool metal_graph_refresh_ratio4_compressor_state(
        ds4_gpu_graph  *g,
        const ds4_model  *model,
        ds4_gpu_tensor *state_kv,
        ds4_gpu_tensor *state_score,
        const ds4_tensor *kv_weight,
        const ds4_tensor *score_weight,
        const ds4_tensor *ape,
        uint32_t          head_dim,
```<｜Assistant｜></think>


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

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

File: ds4.c

```c
LAYER; il++) {
        ok = metal_graph_encode_decode_layer(g,
                                             model,
                                             &weights->layer[il],
                                             il,
                                             pos,
                                             g->layer_raw_cache[il],
                                             g->raw_cap,
                                             raw_row,
                                             n_raw,
                                             token);
        ds4_gpu_tensor *tmp = g->cur_hc;
        g->cur_hc = g->after_ffn_hc;
        g->after_ffn_hc = tmp;
        if (ok && allow_split_flush && split_after_layers != 0 && il + 1u == split_after_layers) {
            ok = ds4_gpu_flush_commands() != 0;
        }
    }

    if (ok && need_logits) {
        ok = metal_graph_encode_output_head(g, model, weights, weights->output->dim[1]);
    }
    return ok;
}

static ds4_gpu_tensor *metal_graph_tensor_row_view(
        ds4_gpu_tensor *base,
        uint32_t          row,
        uint64_t          row_values) {
    return ds4_gpu_tensor_view(base,
                                 (uint64_t)row * row_values * sizeof(float),
                                 row_values * sizeof(float));
}

/* Upload prompt token ids for kernels that need token-aware hash routing. */
static bool metal_graph_upload_prompt_tokens(
        ds4_gpu_tensor *out_tokens,
        const token_vec  *prompt,
        uint32_t          pos0,
        uint32_t          n_tokens) {
    if (!out_tokens || pos0 > (uint32_t)prompt->len || n_tokens > (uint32_t)prompt->len - pos0) {
        return false;
    }

    int32_t *tokens = xmalloc((size_t)n_tokens * sizeof(tokens[0]));
    for (uint32_t i = 0; i < n_tokens; i++) tokens[i] = prompt->v[pos0 + i];

    const bool ok = ds4_gpu_tensor_write(out_tokens,
                                           0,
                                           tokens,
                                           (uint64_t)n_tokens * sizeof(tokens[0])) != 0;
    free(tokens);
    return ok;
}

/* Rebuild ratio-4 compressor state after chunked prefill so a following decode
 * token sees the same rolling compression window. */
static bool metal_graph_refresh_ratio4_compressor_state(
        ds4_gpu_graph  *g,
        const ds4_model  *model,
        ds4_gpu_tensor *state_kv,
        ds4_gpu_tensor *state_score,
        const ds4_tensor *kv_weight,
        const ds4_tensor *score_weight,
        const ds4_tensor *ape,
        uint32_t          head_dim,
```

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

File: ds4.c

```c
LAYER; il++) {
        ok = metal_graph_encode_decode_layer(g,
                                             model,
                                             &weights->layer[il],
                                             il,
                                             pos,
                                             g->layer_raw_cache[il],
                                             g->raw_cap,
                                             raw_row,
                                             n_raw,
                                             token);
        ds4_gpu_tensor *tmp = g->cur_hc;
        g->cur_hc = g->after_ffn_hc;
        g->after_ffn_hc = tmp;
        if (ok && allow_split_flush && split_after_layers != 0 && il + 1u == split_after_layers) {
            ok = ds4_gpu_flush_commands() != 0;
        }
    }

    if (ok && need_logits) {
        ok = metal_graph_encode_output_head(g, model, weights, weights->output->dim[1]);
    }
    return ok;
}

static ds4_gpu_tensor *metal_graph_tensor_row_view(
        ds4_gpu_tensor *base,
        uint32_t          row,
        uint64_t          row_values) {
    return ds4_gpu_tensor_view(base,
                                 (uint64_t)row * row_values * sizeof(float),
                                 row_values * sizeof(float));
}

/* Upload prompt token ids for kernels that need token-aware hash routing. */
static bool metal_graph_upload_prompt_tokens(
        ds4_gpu_tensor *out_tokens,
        const token_vec  *prompt,
        uint32_t          pos0,
        uint32_t          n_tokens) {
    if (!out_tokens || pos0 > (uint32_t)prompt->len || n_tokens > (uint32_t)prompt->len - pos0) {
        return false;
    }

    int32_t *tokens = xmalloc((size_t)n_tokens * sizeof(tokens[0]));
    for (uint32_t i = 0; i < n_tokens; i++) tokens[i] = prompt->v[pos0 + i];

    const bool ok = ds4_gpu_tensor_write(out_tokens,
                                           0,
                                           tokens,
                                           (uint64_t)n_tokens * sizeof(tokens[0])) != 0;
    free(tokens);
    return ok;
}

/* Rebuild ratio-4 compressor state after chunked prefill so a following decode
 * token sees the same rolling compression window. */
static bool metal_graph_refresh_ratio4_compressor_state(
        ds4_gpu_graph  *g,
        const ds4_model  *model,
        ds4_gpu_tensor *state_kv,
        ds4_gpu_tensor *state_score,
        const ds4_tensor *kv_weight,
        const ds4_tensor *score_weight,
        const ds4_tensor *ape,
        uint32_t          head_dim,
```<｜Assistant｜><think>


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

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

File: ds4.c

```c
ds4_gpu_tensor *state_score,
        const ds4_tensor *kv_weight,
        const ds4_tensor *score_weight,
        const ds4_tensor *ape,
        uint32_t          head_dim,
        uint32_t          width,
        uint32_t          pos0,
        uint32_t          n_tokens) {
    if (!g || !model || !state_kv || !state_score || !kv_weight || !score_weight || !ape ||
        head_dim == 0 || width == 0 || n_tokens < 4) {
        return false;
    }

    /*
     * The recurrent ratio-4 state is intentionally rebuilt from the last
     * four tokens using the small-batch projection kernel. The full-chunk
     * projection is already available, but it uses the matrix-matrix path;
     * mixing those two accumulation orders changes a few FP8 rounding
     * decisions in later chunks.
     */
    ds4_gpu_tensor *tail_hc = ds4_gpu_tensor_view(
            g->batch_attn_norm,
            (uint64_t)(n_tokens - 4u) * DS4_N_EMBD * sizeof(float),
            4ull * DS4_N_EMBD * sizeof(float));
    bool ok = tail_hc != NULL;
    if (ok) {
        ok = ds4_gpu_matmul_f16_tensor(g->batch_comp_kv,
                                         model->map,
                                         model->size,
                                         kv_weight->abs_offset,
                                         DS4_N_EMBD,
                                         width,
                                         tail_hc,
                                         4) != 0;
    }
    if (ok) {
        ok = ds4_gpu_matmul_f16_tensor(g->batch_comp_sc,
                                         model->map,
                                         model->size,
                                         score_weight->abs_offset,
                                         DS4_N_EMBD,
                                         width,
                                         tail_hc,
                                         4) != 0;
    }
    if (ok) {
        ok = ds4_gpu_compressor_prefill_state_ratio4_tensor(state_kv,
                                                              state_score,
                                                              g->batch_comp_kv,
                                                              g->batch_comp_sc,
                                                              model->map,
                                                              model->size,
                                                              ape->abs_offset,
                                                              ape->type,
```

<｜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
ds4_gpu_tensor *state_score,
        const ds4_tensor *kv_weight,
        const ds4_tensor *score_weight,
        const ds4_tensor *ape,
        uint32_t          head_dim,
        uint32_t          width,
        uint32_t          pos0,
        uint32_t          n_tokens) {
    if (!g || !model || !state_kv || !state_score || !kv_weight || !score_weight || !ape ||
        head_dim == 0 || width == 0 || n_tokens < 4) {
        return false;
    }

    /*
     * The recurrent ratio-4 state is intentionally rebuilt from the last
     * four tokens using the small-batch projection kernel. The full-chunk
     * projection is already available, but it uses the matrix-matrix path;
     * mixing those two accumulation orders changes a few FP8 rounding
     * decisions in later chunks.
     */
    ds4_gpu_tensor *tail_hc = ds4_gpu_tensor_view(
            g->batch_attn_norm,
            (uint64_t)(n_tokens - 4u) * DS4_N_EMBD * sizeof(float),
            4ull * DS4_N_EMBD * sizeof(float));
    bool ok = tail_hc != NULL;
    if (ok) {
        ok = ds4_gpu_matmul_f16_tensor(g->batch_comp_kv,
                                         model->map,
                                         model->size,
                                         kv_weight->abs_offset,
                                         DS4_N_EMBD,
                                         width,
                                         tail_hc,
                                         4) != 0;
    }
    if (ok) {
        ok = ds4_gpu_matmul_f16_tensor(g->batch_comp_sc,
                                         model->map,
                                         model->size,
                                         score_weight->abs_offset,
                                         DS4_N_EMBD,
                                         width,
                                         tail_hc,
                                         4) != 0;
    }
    if (ok) {
        ok = ds4_gpu_compressor_prefill_state_ratio4_tensor(state_kv,
                                                              state_score,
                                                              g->batch_comp_kv,
                                                              g->batch_comp_sc,
                                                              model->map,
                                                              model->size,
                                                              ape->abs_offset,
                                                              ape->type,
```<｜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
ds4_gpu_tensor *state_score,
        const ds4_tensor *kv_weight,
        const ds4_tensor *score_weight,
        const ds4_tensor *ape,
        uint32_t          head_dim,
        uint32_t          width,
        uint32_t          pos0,
        uint32_t          n_tokens) {
    if (!g || !model || !state_kv || !state_score || !kv_weight || !score_weight || !ape ||
        head_dim == 0 || width == 0 || n_tokens < 4) {
        return false;
    }

    /*
     * The recurrent ratio-4 state is intentionally rebuilt from the last
     * four tokens using the small-batch projection kernel. The full-chunk
     * projection is already available, but it uses the matrix-matrix path;
     * mixing those two accumulation orders changes a few FP8 rounding
     * decisions in later chunks.
     */
    ds4_gpu_tensor *tail_hc = ds4_gpu_tensor_view(
            g->batch_attn_norm,
            (uint64_t)(n_tokens - 4u) * DS4_N_EMBD * sizeof(float),
            4ull * DS4_N_EMBD * sizeof(float));
    bool ok = tail_hc != NULL;
    if (ok) {
        ok = ds4_gpu_matmul_f16_tensor(g->batch_comp_kv,
                                         model->map,
                                         model->size,
                                         kv_weight->abs_offset,
                                         DS4_N_EMBD,
                                         width,
                                         tail_hc,
                                         4) != 0;
    }
    if (ok) {
        ok = ds4_gpu_matmul_f16_tensor(g->batch_comp_sc,
                                         model->map,
                                         model->size,
                                         score_weight->abs_offset,
                                         DS4_N_EMBD,
                                         width,
                                         tail_hc,
                                         4) != 0;
    }
    if (ok) {
        ok = ds4_gpu_compressor_prefill_state_ratio4_tensor(state_kv,
                                                              state_score,
                                                              g->batch_comp_kv,
                                                              g->batch_comp_sc,
                                                              model->map,
                                                              model->size,
                                                              ape->abs_offset,
                                                              ape->type,
```

<｜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
ds4_gpu_tensor *state_score,
        const ds4_tensor *kv_weight,
        const ds4_tensor *score_weight,
        const ds4_tensor *ape,
        uint32_t          head_dim,
        uint32_t          width,
        uint32_t          pos0,
        uint32_t          n_tokens) {
    if (!g || !model || !state_kv || !state_score || !kv_weight || !score_weight || !ape ||
        head_dim == 0 || width == 0 || n_tokens < 4) {
        return false;
    }

    /*
     * The recurrent ratio-4 state is intentionally rebuilt from the last
     * four tokens using the small-batch projection kernel. The full-chunk
     * projection is already available, but it uses the matrix-matrix path;
     * mixing those two accumulation orders changes a few FP8 rounding
     * decisions in later chunks.
     */
    ds4_gpu_tensor *tail_hc = ds4_gpu_tensor_view(
            g->batch_attn_norm,
            (uint64_t)(n_tokens - 4u) * DS4_N_EMBD * sizeof(float),
            4ull * DS4_N_EMBD * sizeof(float));
    bool ok = tail_hc != NULL;
    if (ok) {
        ok = ds4_gpu_matmul_f16_tensor(g->batch_comp_kv,
                                         model->map,
                                         model->size,
                                         kv_weight->abs_offset,
                                         DS4_N_EMBD,
                                         width,
                                         tail_hc,
                                         4) != 0;
    }
    if (ok) {
        ok = ds4_gpu_matmul_f16_tensor(g->batch_comp_sc,
                                         model->map,
                                         model->size,
                                         score_weight->abs_offset,
                                         DS4_N_EMBD,
                                         width,
                                         tail_hc,
                                         4) != 0;
    }
    if (ok) {
        ok = ds4_gpu_compressor_prefill_state_ratio4_tensor(state_kv,
                                                              state_score,
                                                              g->batch_comp_kv,
                                                              g->batch_comp_sc,
                                                              model->map,
                                                              model->size,
                                                              ape->abs_offset,
                                                              ape->type,
```<｜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
model->size,
                                                              ape->abs_offset,
                                                              ape->type,
                                                              head_dim,
                                                              pos0 + n_tokens - 4u) != 0;
    }
    ds4_gpu_tensor_free(tail_hc);
    return ok;
}

/* CPU fallback for seeding batched HC state from token embeddings.  It is still
 * useful for tiny speculative verifier batches where a separate GPU embedding
 * command buffer costs more than the small host write. */
static bool metal_graph_upload_prompt_embeddings_hc_cpu(
        ds4_gpu_tensor   *out_hc,
        const ds4_model    *model,
        const ds4_weights  *weights,
        const token_vec    *prompt,
        uint32_t            pos0,
        uint32_t            n_tokens) {
    if (pos0 > (uint32_t)prompt->len || n_tokens > (uint32_t)prompt->len - pos0) return false;
    const uint64_t hc_dim = (uint64_t)DS4_N_HC * DS4_N_EMBD;
    const uint64_t total = (uint64_t)n_tokens * hc_dim;
    float *hc = xmalloc((size_t)total * sizeof(hc[0]));
    float *plain = xmalloc((size_t)DS4_N_EMBD * sizeof(plain[0]));

    for (uint32_t t = 0; t < n_tokens; t++) {
        embed_token_f16(model, weights, prompt->v[pos0 + t], plain);
        float *dst = hc + (uint64_t)t * hc_dim;
        for (uint32_t h = 0; h < DS4_N_HC; h++) {
            memcpy(dst + (uint64_t)h * DS4_N_EMBD,
                   plain,
                   (size_t)DS4_N_EMBD * sizeof(plain[0]));
        }
    }

    const bool ok = ds4_gpu_tensor_write(out_hc, 0, hc, total * sizeof(hc[0])) != 0;
    free(plain);
    free(hc);
    return ok;
}

/* Seed the batched HC state from token ids: every HC stream starts as the same
 * 4096-wide embedding.  Long prefill chunks use the Metal get-rows/repeat
 * kernel so the CPU does not build and upload a large [token, HC, dim] tensor. */
static bool metal_graph_upload_prompt_embeddings_hc(
        ds4_gpu_tensor   *out_hc,
        ds4_gpu_tensor   *tokens,
        const ds4_model    *model,
        const ds4_weights  *weights,
        const token_vec    *prompt,
        uint32_t            pos0,
        uint32_t            n_tokens) {
    if (pos0 > (uint32_t)prompt->len || n_tokens > (uint32_t)prompt->len - pos0) return false;

    uint32_t gpu_min = 512;
    const char *gpu_min_env = getenv("DS4_METAL_GPU_BATCH_EMBED_MIN");
    if (gpu_min_env && gpu_min_env[0]) {
        char *end = NULL;
        unsigned long v = strtoul(gpu_min_env, &end, 10);
```

<｜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
model->size,
                                                              ape->abs_offset,
                                                              ape->type,
                                                              head_dim,
                                                              pos0 + n_tokens - 4u) != 0;
    }
    ds4_gpu_tensor_free(tail_hc);
    return ok;
}

/* CPU fallback for seeding batched HC state from token embeddings.  It is still
 * useful for tiny speculative verifier batches where a separate GPU embedding
 * command buffer costs more than the small host write. */
static bool metal_graph_upload_prompt_embeddings_hc_cpu(
        ds4_gpu_tensor   *out_hc,
        const ds4_model    *model,
        const ds4_weights  *weights,
        const token_vec    *prompt,
        uint32_t            pos0,
        uint32_t            n_tokens) {
    if (pos0 > (uint32_t)prompt->len || n_tokens > (uint32_t)prompt->len - pos0) return false;
    const uint64_t hc_dim = (uint64_t)DS4_N_HC * DS4_N_EMBD;
    const uint64_t total = (uint64_t)n_tokens * hc_dim;
    float *hc = xmalloc((size_t)total * sizeof(hc[0]));
    float *plain = xmalloc((size_t)DS4_N_EMBD * sizeof(plain[0]));

    for (uint32_t t = 0; t < n_tokens; t++) {
        embed_token_f16(model, weights, prompt->v[pos0 + t], plain);
        float *dst = hc + (uint64_t)t * hc_dim;
        for (uint32_t h = 0; h < DS4_N_HC; h++) {
            memcpy(dst + (uint64_t)h * DS4_N_EMBD,
                   plain,
                   (size_t)DS4_N_EMBD * sizeof(plain[0]));
        }
    }

    const bool ok = ds4_gpu_tensor_write(out_hc, 0, hc, total * sizeof(hc[0])) != 0;
    free(plain);
    free(hc);
    return ok;
}

/* Seed the batched HC state from token ids: every HC stream starts as the same
 * 4096-wide embedding.  Long prefill chunks use the Metal get-rows/repeat
 * kernel so the CPU does not build and upload a large [token, HC, dim] tensor. */
static bool metal_graph_upload_prompt_embeddings_hc(
        ds4_gpu_tensor   *out_hc,
        ds4_gpu_tensor   *tokens,
        const ds4_model    *model,
        const ds4_weights  *weights,
        const token_vec    *prompt,
        uint32_t            pos0,
        uint32_t            n_tokens) {
    if (pos0 > (uint32_t)prompt->len || n_tokens > (uint32_t)prompt->len - pos0) return false;

    uint32_t gpu_min = 512;
    const char *gpu_min_env = getenv("DS4_METAL_GPU_BATCH_EMBED_MIN");
    if (gpu_min_env && gpu_min_env[0]) {
        char *end = NULL;
        unsigned long v = strtoul(gpu_min_env, &end, 10);
```<｜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
model->size,
                                                              ape->abs_offset,
                                                              ape->type,
                                                              head_dim,
                                                              pos0 + n_tokens - 4u) != 0;
    }
    ds4_gpu_tensor_free(tail_hc);
    return ok;
}

/* CPU fallback for seeding batched HC state from token embeddings.  It is still
 * useful for tiny speculative verifier batches where a separate GPU embedding
 * command buffer costs more than the small host write. */
static bool metal_graph_upload_prompt_embeddings_hc_cpu(
        ds4_gpu_tensor   *out_hc,
        const ds4_model    *model,
        const ds4_weights  *weights,
        const token_vec    *prompt,
        uint32_t            pos0,
        uint32_t            n_tokens) {
    if (pos0 > (uint32_t)prompt->len || n_tokens > (uint32_t)prompt->len - pos0) return false;
    const uint64_t hc_dim = (uint64_t)DS4_N_HC * DS4_N_EMBD;
    const uint64_t total = (uint64_t)n_tokens * hc_dim;
    float *hc = xmalloc((size_t)total * sizeof(hc[0]));
    float *plain = xmalloc((size_t)DS4_N_EMBD * sizeof(plain[0]));

    for (uint32_t t = 0; t < n_tokens; t++) {
        embed_token_f16(model, weights, prompt->v[pos0 + t], plain);
        float *dst = hc + (uint64_t)t * hc_dim;
        for (uint32_t h = 0; h < DS4_N_HC; h++) {
            memcpy(dst + (uint64_t)h * DS4_N_EMBD,
                   plain,
                   (size_t)DS4_N_EMBD * sizeof(plain[0]));
        }
    }

    const bool ok = ds4_gpu_tensor_write(out_hc, 0, hc, total * sizeof(hc[0])) != 0;
    free(plain);
    free(hc);
    return ok;
}

/* Seed the batched HC state from token ids: every HC stream starts as the same
 * 4096-wide embedding.  Long prefill chunks use the Metal get-rows/repeat
 * kernel so the CPU does not build and upload a large [token, HC, dim] tensor. */
static bool metal_graph_upload_prompt_embeddings_hc(
        ds4_gpu_tensor   *out_hc,
        ds4_gpu_tensor   *tokens,
        const ds4_model    *model,
        const ds4_weights  *weights,
        const token_vec    *prompt,
        uint32_t            pos0,
        uint32_t            n_tokens) {
    if (pos0 > (uint32_t)prompt->len || n_tokens > (uint32_t)prompt->len - pos0) return false;

    uint32_t gpu_min = 512;
    const char *gpu_min_env = getenv("DS4_METAL_GPU_BATCH_EMBED_MIN");
    if (gpu_min_env && gpu_min_env[0]) {
        char *end = NULL;
        unsigned long v = strtoul(gpu_min_env, &end, 10);
```

<｜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
model->size,
                                                              ape->abs_offset,
                                                              ape->type,
                                                              head_dim,
                                                              pos0 + n_tokens - 4u) != 0;
    }
    ds4_gpu_tensor_free(tail_hc);
    return ok;
}

/* CPU fallback for seeding batched HC state from token embeddings.  It is still
 * useful for tiny speculative verifier batches where a separate GPU embedding
 * command buffer costs more than the small host write. */
static bool metal_graph_upload_prompt_embeddings_hc_cpu(
        ds4_gpu_tensor   *out_hc,
        const ds4_model    *model,
        const ds4_weights  *weights,
        const token_vec    *prompt,
        uint32_t            pos0,
        uint32_t            n_tokens) {
    if (pos0 > (uint32_t)prompt->len || n_tokens > (uint32_t)prompt->len - pos0) return false;
    const uint64_t hc_dim = (uint64_t)DS4_N_HC * DS4_N_EMBD;
    const uint64_t total = (uint64_t)n_tokens * hc_dim;
    float *hc = xmalloc((size_t)total * sizeof(hc[0]));
    float *plain = xmalloc((size_t)DS4_N_EMBD * sizeof(plain[0]));

    for (uint32_t t = 0; t < n_tokens; t++) {
        embed_token_f16(model, weights, prompt->v[pos0 + t], plain);
        float *dst = hc + (uint64_t)t * hc_dim;
        for (uint32_t h = 0; h < DS4_N_HC; h++) {
            memcpy(dst + (uint64_t)h * DS4_N_EMBD,
                   plain,
                   (size_t)DS4_N_EMBD * sizeof(plain[0]));
        }
    }

    const bool ok = ds4_gpu_tensor_write(out_hc, 0, hc, total * sizeof(hc[0])) != 0;
    free(plain);
    free(hc);
    return ok;
}

/* Seed the batched HC state from token ids: every HC stream starts as the same
 * 4096-wide embedding.  Long prefill chunks use the Metal get-rows/repeat
 * kernel so the CPU does not build and upload a large [token, HC, dim] tensor. */
static bool metal_graph_upload_prompt_embeddings_hc(
        ds4_gpu_tensor   *out_hc,
        ds4_gpu_tensor   *tokens,
        const ds4_model    *model,
        const ds4_weights  *weights,
        const token_vec    *prompt,
        uint32_t            pos0,
        uint32_t            n_tokens) {
    if (pos0 > (uint32_t)prompt->len || n_tokens > (uint32_t)prompt->len - pos0) return false;

    uint32_t gpu_min = 512;
    const char *gpu_min_env = getenv("DS4_METAL_GPU_BATCH_EMBED_MIN");
    if (gpu_min_env && gpu_min_env[0]) {
        char *end = NULL;
        unsigned long v = strtoul(gpu_min_env, &end, 10);
```<｜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
*gpu_min_env = getenv("DS4_METAL_GPU_BATCH_EMBED_MIN");
    if (gpu_min_env && gpu_min_env[0]) {
        char *end = NULL;
        unsigned long v = strtoul(gpu_min_env, &end, 10);
        if (end != gpu_min_env && v <= UINT32_MAX) gpu_min = (uint32_t)v;
    }

    if (tokens && n_tokens >= gpu_min) {
        return ds4_gpu_embed_tokens_hc_tensor(out_hc,
                                                tokens,
                                                model->map,
                                                model->size,
                                                weights->token_embd->abs_offset,
                                                (uint32_t)weights->token_embd->dim[1],
                                                n_tokens,
                                                DS4_N_EMBD,
                                                DS4_N_HC) != 0;
    }

    return metal_graph_upload_prompt_embeddings_hc_cpu(out_hc,
                                                       model,
                                                       weights,
                                                       prompt,
                                                       pos0,
                                                       n_tokens);
}

static bool metal_graph_warmup_prefill_kernels(
        ds4_gpu_graph   *g,
        const ds4_model   *model,
        const ds4_weights *weights,
        uint32_t           n_tokens) {
    static bool warmed = false;
    if (warmed || getenv("DS4_METAL_NO_PREFILL_KERNEL_WARMUP") != NULL) return true;

    /*
     * The first batched F16 matmul can pay Metal's one-time pipeline execution
     * cost. Run the same HC attention projection on scratch storage before the
     * measured prefill. The output is overwritten by the real graph.
     */
    if (n_tokens <= 8) return true;

    const uint64_t hc_dim = (uint64_t)DS4_N_HC * DS4_N_EMBD;
    const uint64_t mix_hc = 2ull * DS4_N_HC + (uint64_t)DS4_N_HC * DS4_N_HC;

    bool ok = ds4_gpu_begin_commands() != 0;
    if (ok) {
        ok = ds4_gpu_matmul_f16_tensor(g->batch_hc_mix,
                                         model->map,
                                         model->size,
                                         weights->layer[0].hc_attn_fn->abs_offset,
                                         hc_dim,
                                         mix_hc,
                                         g->batch_flat_hc,
                                         n_tokens) != 0;
    }
    if (ok) ok = ds4_gpu_end_commands() != 0;
    if (!ok) {
```

<｜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
*gpu_min_env = getenv("DS4_METAL_GPU_BATCH_EMBED_MIN");
    if (gpu_min_env && gpu_min_env[0]) {
        char *end = NULL;
        unsigned long v = strtoul(gpu_min_env, &end, 10);
        if (end != gpu_min_env && v <= UINT32_MAX) gpu_min = (uint32_t)v;
    }

    if (tokens && n_tokens >= gpu_min) {
        return ds4_gpu_embed_tokens_hc_tensor(out_hc,
                                                tokens,
                                                model->map,
                                                model->size,
                                                weights->token_embd->abs_offset,
                                                (uint32_t)weights->token_embd->dim[1],
                                                n_tokens,
                                                DS4_N_EMBD,
                                                DS4_N_HC) != 0;
    }

    return metal_graph_upload_prompt_embeddings_hc_cpu(out_hc,
                                                       model,
                                                       weights,
                                                       prompt,
                                                       pos0,
                                                       n_tokens);
}

static bool metal_graph_warmup_prefill_kernels(
        ds4_gpu_graph   *g,
        const ds4_model   *model,
        const ds4_weights *weights,
        uint32_t           n_tokens) {
    static bool warmed = false;
    if (warmed || getenv("DS4_METAL_NO_PREFILL_KERNEL_WARMUP") != NULL) return true;

    /*
     * The first batched F16 matmul can pay Metal's one-time pipeline execution
     * cost. Run the same HC attention projection on scratch storage before the
     * measured prefill. The output is overwritten by the real graph.
     */
    if (n_tokens <= 8) return true;

    const uint64_t hc_dim = (uint64_t)DS4_N_HC * DS4_N_EMBD;
    const uint64_t mix_hc = 2ull * DS4_N_HC + (uint64_t)DS4_N_HC * DS4_N_HC;

    bool ok = ds4_gpu_begin_commands() != 0;
    if (ok) {
        ok = ds4_gpu_matmul_f16_tensor(g->batch_hc_mix,
                                         model->map,
                                         model->size,
                                         weights->layer[0].hc_attn_fn->abs_offset,
                                         hc_dim,
                                         mix_hc,
                                         g->batch_flat_hc,
                                         n_tokens) != 0;
    }
    if (ok) ok = ds4_gpu_end_commands() != 0;
    if (!ok) {
```<｜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
*gpu_min_env = getenv("DS4_METAL_GPU_BATCH_EMBED_MIN");
    if (gpu_min_env && gpu_min_env[0]) {
        char *end = NULL;
        unsigned long v = strtoul(gpu_min_env, &end, 10);
        if (end != gpu_min_env && v <= UINT32_MAX) gpu_min = (uint32_t)v;
    }

    if (tokens && n_tokens >= gpu_min) {
        return ds4_gpu_embed_tokens_hc_tensor(out_hc,
                                                tokens,
                                                model->map,
                                                model->size,
                                                weights->token_embd->abs_offset,
                                                (uint32_t)weights->token_embd->dim[1],
                                                n_tokens,
                                                DS4_N_EMBD,
                                                DS4_N_HC) != 0;
    }

    return metal_graph_upload_prompt_embeddings_hc_cpu(out_hc,
                                                       model,
                                                       weights,
                                                       prompt,
                                                       pos0,
                                                       n_tokens);
}

static bool metal_graph_warmup_prefill_kernels(
        ds4_gpu_graph   *g,
        const ds4_model   *model,
        const ds4_weights *weights,
        uint32_t           n_tokens) {
    static bool warmed = false;
    if (warmed || getenv("DS4_METAL_NO_PREFILL_KERNEL_WARMUP") != NULL) return true;

    /*
     * The first batched F16 matmul can pay Metal's one-time pipeline execution
     * cost. Run the same HC attention projection on scratch storage before the
     * measured prefill. The output is overwritten by the real graph.
     */
    if (n_tokens <= 8) return true;

    const uint64_t hc_dim = (uint64_t)DS4_N_HC * DS4_N_EMBD;
    const uint64_t mix_hc = 2ull * DS4_N_HC + (uint64_t)DS4_N_HC * DS4_N_HC;

    bool ok = ds4_gpu_begin_commands() != 0;
    if (ok) {
        ok = ds4_gpu_matmul_f16_tensor(g->batch_hc_mix,
                                         model->map,
                                         model->size,
                                         weights->layer[0].hc_attn_fn->abs_offset,
                                         hc_dim,
                                         mix_hc,
                                         g->batch_flat_hc,
                                         n_tokens) != 0;
    }
    if (ok) ok = ds4_gpu_end_commands() != 0;
    if (!ok) {
```

<｜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
*gpu_min_env = getenv("DS4_METAL_GPU_BATCH_EMBED_MIN");
    if (gpu_min_env && gpu_min_env[0]) {
        char *end = NULL;
        unsigned long v = strtoul(gpu_min_env, &end, 10);
        if (end != gpu_min_env && v <= UINT32_MAX) gpu_min = (uint32_t)v;
    }

    if (tokens && n_tokens >= gpu_min) {
        return ds4_gpu_embed_tokens_hc_tensor(out_hc,
                                                tokens,
                                                model->map,
                                                model->size,
                                                weights->token_embd->abs_offset,
                                                (uint32_t)weights->token_embd->dim[1],
                                                n_tokens,
                                                DS4_N_EMBD,
                                                DS4_N_HC) != 0;
    }

    return metal_graph_upload_prompt_embeddings_hc_cpu(out_hc,
                                                       model,
                                                       weights,
                                                       prompt,
                                                       pos0,
                                                       n_tokens);
}

static bool metal_graph_warmup_prefill_kernels(
        ds4_gpu_graph   *g,
        const ds4_model   *model,
        const ds4_weights *weights,
        uint32_t           n_tokens) {
    static bool warmed = false;
    if (warmed || getenv("DS4_METAL_NO_PREFILL_KERNEL_WARMUP") != NULL) return true;

    /*
     * The first batched F16 matmul can pay Metal's one-time pipeline execution
     * cost. Run the same HC attention projection on scratch storage before the
     * measured prefill. The output is overwritten by the real graph.
     */
    if (n_tokens <= 8) return true;

    const uint64_t hc_dim = (uint64_t)DS4_N_HC * DS4_N_EMBD;
    const uint64_t mix_hc = 2ull * DS4_N_HC + (uint64_t)DS4_N_HC * DS4_N_HC;

    bool ok = ds4_gpu_begin_commands() != 0;
    if (ok) {
        ok = ds4_gpu_matmul_f16_tensor(g->batch_hc_mix,
                                         model->map,
                                         model->size,
                                         weights->layer[0].hc_attn_fn->abs_offset,
                                         hc_dim,
                                         mix_hc,
                                         g->batch_flat_hc,
                                         n_tokens) != 0;
    }
    if (ok) ok = ds4_gpu_end_commands() != 0;
    if (!ok) {
```<｜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
g->batch_flat_hc,
                                         n_tokens) != 0;
    }
    if (ok) ok = ds4_gpu_end_commands() != 0;
    if (!ok) {
        fprintf(stderr, "ds4: Metal prefill kernel warmup failed\n");
        return false;
    }

    warmed = true;
    return true;
}

/* Encode the batched prefill attention half for one layer.  It mirrors the CPU
 * layer-major path: HC pre/norm, Q/KV, cache/compression, prefix attention. */
static bool metal_graph_indexer_stage_profile_boundary(
        const char *stage,
        uint32_t    il,
        uint32_t    pos0,
        uint32_t    n_tokens,
        uint32_t    n_comp,
        double     *stage_t0) {
    if (ds4_gpu_end_commands() == 0) return false;
    const double now = now_sec();
    if (stage != NULL) {
        fprintf(stderr,
                "ds4: metal indexer stage layer=%u pos=%u tokens=%u comp=%u %s=%.3f ms\n",
                il,
                pos0,
                n_tokens,
                n_comp,
                stage,
                (now - *stage_t0) * 1000.0);
    }
    *stage_t0 = now;
    return ds4_gpu_begin_commands() != 0;
}

/* Optional prefill stage profiler. It intentionally ends the current Metal
 * command buffer and waits, so the printed number includes encoding plus GPU
 * execution for the stage just emitted. This is disabled by default because it
 * adds synchronization points and changes scheduling. */
static bool metal_graph_layer_stage_profile_boundary(
        const char *part,
        const char *stage,
        uint32_t    il,
        uint32_t    pos0,
        uint32_t    n_tokens,
        double     *stage_t0) {
    if (ds4_gpu_end_commands() == 0) return false;
    const double now = now_sec();
    fprintf(stderr,
            "ds4: metal layer stage part=%s layer=%u pos=%u tokens=%u %s=%.3f ms\n",
            part,
            il,
            pos0,
            n_tokens,
            stage,
            (now - *stage_t0) * 1000.0);
    *stage_t0 = now;
    return ds4_gpu_begin_commands() != 0;
}

static bool metal_graph_q_stage_profile_boundary(
        const char *stage,
        uint32_t    il,
        uint32_t    pos0,
        uint32_t    n_tokens,
        double     *stage_t0) {
    if (ds4_gpu_end_commands() == 0) return false;
    const double now = now_sec();
    fprintf(stderr,
            "ds4: metal Q path stage layer=%u pos=%u tokens=%u %s=%.3f ms\n",
            il,
            pos0,
            n_tokens,
            stage,
            (now - *stage_t0) * 1000.0);
    *stage_t0 = now;
```

<｜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
g->batch_flat_hc,
                                         n_tokens) != 0;
    }
    if (ok) ok = ds4_gpu_end_commands() != 0;
    if (!ok) {
        fprintf(stderr, "ds4: Metal prefill kernel warmup failed\n");
        return false;
    }

    warmed = true;
    return true;
}

/* Encode the batched prefill attention half for one layer.  It mirrors the CPU
 * layer-major path: HC pre/norm, Q/KV, cache/compression, prefix attention. */
static bool metal_graph_indexer_stage_profile_boundary(
        const char *stage,
        uint32_t    il,
        uint32_t    pos0,
        uint32_t    n_tokens,
        uint32_t    n_comp,
        double     *stage_t0) {
    if (ds4_gpu_end_commands() == 0) return false;
    const double now = now_sec();
    if (stage != NULL) {
        fprintf(stderr,
                "ds4: metal indexer stage layer=%u pos=%u tokens=%u comp=%u %s=%.3f ms\n",
                il,
                pos0,
                n_tokens,
                n_comp,
                stage,
                (now - *stage_t0) * 1000.0);
    }
    *stage_t0 = now;
    return ds4_gpu_begin_commands() != 0;
}

/* Optional prefill stage profiler. It intentionally ends the current Metal
 * command buffer and waits, so the printed number includes encoding plus GPU
 * execution for the stage just emitted. This is disabled by default because it
 * adds synchronization points and changes scheduling. */
static bool metal_graph_layer_stage_profile_boundary(
        const char *part,
        const char *stage,
        uint32_t    il,
        uint32_t    pos0,
        uint32_t    n_tokens,
        double     *stage_t0) {
    if (ds4_gpu_end_commands() == 0) return false;
    const double now = now_sec();
    fprintf(stderr,
            "ds4: metal layer stage part=%s layer=%u pos=%u tokens=%u %s=%.3f ms\n",
            part,
            il,
            pos0,
            n_tokens,
            stage,
            (now - *stage_t0) * 1000.0);
    *stage_t0 = now;
    return ds4_gpu_begin_commands() != 0;
}

static bool metal_graph_q_stage_profile_boundary(
        const char *stage,
        uint32_t    il,
        uint32_t    pos0,
        uint32_t    n_tokens,
        double     *stage_t0) {
    if (ds4_gpu_end_commands() == 0) return false;
    const double now = now_sec();
    fprintf(stderr,
            "ds4: metal Q path stage layer=%u pos=%u tokens=%u %s=%.3f ms\n",
            il,
            pos0,
            n_tokens,
            stage,
            (now - *stage_t0) * 1000.0);
    *stage_t0 = now;
```<｜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
g->batch_flat_hc,
                                         n_tokens) != 0;
    }
    if (ok) ok = ds4_gpu_end_commands() != 0;
    if (!ok) {
        fprintf(stderr, "ds4: Metal prefill kernel warmup failed\n");
        return false;
    }

    warmed = true;
    return true;
}

/* Encode the batched prefill attention half for one layer.  It mirrors the CPU
 * layer-major path: HC pre/norm, Q/KV, cache/compression, prefix attention. */
static bool metal_graph_indexer_stage_profile_boundary(
        const char *stage,
        uint32_t    il,
        uint32_t    pos0,
        uint32_t    n_tokens,
        uint32_t    n_comp,
        double     *stage_t0) {
    if (ds4_gpu_end_commands() == 0) return false;
    const double now = now_sec();
    if (stage != NULL) {
        fprintf(stderr,
                "ds4: metal indexer stage layer=%u pos=%u tokens=%u comp=%u %s=%.3f ms\n",
                il,
                pos0,
                n_tokens,
                n_comp,
                stage,
                (now - *stage_t0) * 1000.0);
    }
    *stage_t0 = now;
    return ds4_gpu_begin_commands() != 0;
}

/* Optional prefill stage profiler. It intentionally ends the current Metal
 * command buffer and waits, so the printed number includes encoding plus GPU
 * execution for the stage just emitted. This is disabled by default because it
 * adds synchronization points and changes scheduling. */
static bool metal_graph_layer_stage_profile_boundary(
        const char *part,
        const char *stage,
        uint32_t    il,
        uint32_t    pos0,
        uint32_t    n_tokens,
        double     *stage_t0) {
    if (ds4_gpu_end_commands() == 0) return false;
    const double now = now_sec();
    fprintf(stderr,
            "ds4: metal layer stage part=%s layer=%u pos=%u tokens=%u %s=%.3f ms\n",
            part,
            il,
            pos0,
            n_tokens,
            stage,
            (now - *stage_t0) * 1000.0);
    *stage_t0 = now;
    return ds4_gpu_begin_commands() != 0;
}

static bool metal_graph_q_stage_profile_boundary(
        const char *stage,
        uint32_t    il,
        uint32_t    pos0,
        uint32_t    n_tokens,
        double     *stage_t0) {
    if (ds4_gpu_end_commands() == 0) return false;
    const double now = now_sec();
    fprintf(stderr,
            "ds4: metal Q path stage layer=%u pos=%u tokens=%u %s=%.3f ms\n",
            il,
            pos0,
            n_tokens,
            stage,
            (now - *stage_t0) * 1000.0);
    *stage_t0 = now;
```

<｜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
g->batch_flat_hc,
                                         n_tokens) != 0;
    }
    if (ok) ok = ds4_gpu_end_commands() != 0;
    if (!ok) {
        fprintf(stderr, "ds4: Metal prefill kernel warmup failed\n");
        return false;
    }

    warmed = true;
    return true;
}

/* Encode the batched prefill attention half for one layer.  It mirrors the CPU
 * layer-major path: HC pre/norm, Q/KV, cache/compression, prefix attention. */
static bool metal_graph_indexer_stage_profile_boundary(
        const char *stage,
        uint32_t    il,
        uint32_t    pos0,
        uint32_t    n_tokens,
        uint32_t    n_comp,
        double     *stage_t0) {
    if (ds4_gpu_end_commands() == 0) return false;
    const double now = now_sec();
    if (stage != NULL) {
        fprintf(stderr,
                "ds4: metal indexer stage layer=%u pos=%u tokens=%u comp=%u %s=%.3f ms\n",
                il,
                pos0,
                n_tokens,
                n_comp,
                stage,
                (now - *stage_t0) * 1000.0);
    }
    *stage_t0 = now;
    return ds4_gpu_begin_commands() != 0;
}

/* Optional prefill stage profiler. It intentionally ends the current Metal
 * command buffer and waits, so the printed number includes encoding plus GPU
 * execution for the stage just emitted. This is disabled by default because it
 * adds synchronization points and changes scheduling. */
static bool metal_graph_layer_stage_profile_boundary(
        const char *part,
        const char *stage,
        uint32_t    il,
        uint32_t    pos0,
        uint32_t    n_tokens,
        double     *stage_t0) {
    if (ds4_gpu_end_commands() == 0) return false;
    const double now = now_sec();
    fprintf(stderr,
            "ds4: metal layer stage part=%s layer=%u pos=%u tokens=%u %s=%.3f ms\n",
            part,
            il,
            pos0,
            n_tokens,
            stage,
            (now - *stage_t0) * 1000.0);
    *stage_t0 = now;
    return ds4_gpu_begin_commands() != 0;
}

static bool metal_graph_q_stage_profile_boundary(
        const char *stage,
        uint32_t    il,
        uint32_t    pos0,
        uint32_t    n_tokens,
        double     *stage_t0) {
    if (ds4_gpu_end_commands() == 0) return false;
    const double now = now_sec();
    fprintf(stderr,
            "ds4: metal Q path stage layer=%u pos=%u tokens=%u %s=%.3f ms\n",
            il,
            pos0,
            n_tokens,
            stage,
            (now - *stage_t0) * 1000.0);
    *stage_t0 = now;
```<｜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
ge layer=%u pos=%u tokens=%u %s=%.3f ms\n",
            il,
            pos0,
            n_tokens,
            stage,
            (now - *stage_t0) * 1000.0);
    *stage_t0 = now;
    return ds4_gpu_begin_commands() != 0;
}

static bool metal_graph_encode_layer_attention_batch(
        ds4_gpu_graph  *g,
        const ds4_model        *model,
        const ds4_layer_weights *layer,
        uint32_t                il,
        uint32_t                pos0,
        uint32_t                n_tokens) {
    if (n_tokens == 0 || n_tokens > g->prefill_cap) return false;

    const uint64_t hc_dim = (uint64_t)DS4_N_HC * DS4_N_EMBD;
    const uint64_t mix_hc = 2ull * DS4_N_HC + (uint64_t)DS4_N_HC * DS4_N_HC;
    const uint64_t q_rank = layer->attn_q_a->dim[1];
    const uint64_t q_dim = (uint64_t)DS4_N_HEAD * DS4_N_HEAD_DIM;
    const uint32_t n_groups = DS4_N_OUT_GROUP;
    const uint32_t group_heads = DS4_N_HEAD / n_groups;
    const uint32_t group_dim = DS4_N_HEAD_DIM * group_heads;
    const uint32_t rank = DS4_N_LORA_O;
    const uint32_t ratio = ds4_layer_compress_ratio(il);
    const bool compressed = ratio != 0;
    const bool zero_prefix = pos0 == 0;
    const bool index_stage_profile = getenv("DS4_METAL_INDEXER_STAGE_PROFILE") != NULL;
    const bool layer_stage_profile = getenv("DS4_METAL_LAYER_STAGE_PROFILE") != NULL;
    const bool q_stage_profile = getenv("DS4_METAL_Q_STAGE_PROFILE") != NULL;
    double layer_stage_t0 = layer_stage_profile ? now_sec() : 0.0;
    double q_stage_t0 = q_stage_profile ? now_sec() : 0.0;
#define DS4_METAL_PROFILE_ATTN_STAGE(name) do { \
        if (ok && layer_stage_profile) { \
            ok = metal_graph_layer_stage_profile_boundary("attn", (name), il, pos0, n_tokens, &layer_stage_t0); \
        } \
    } while (0)
#define DS4_METAL_PROFILE_Q_STAGE(name) do { \
        if (ok && q_stage_profile) { \
            ok = metal_graph_q_stage_profile_boundary((name), il, pos0, n_tokens, &q_stage_t0); \
        } \
    } while (0)
    const float freq_base = layer_rope_freq_base(il);
    const float freq_scale = layer_rope_freq_scale(il);
    const float ext_factor = compressed && DS4_ROPE_SCALE_FACTOR > 1.0f ? 1.0f : 0.0f;
    float attn_factor = 1.0f;
    if (ext_factor != 0.0f && freq_scale > 0.0f) {
        attn_factor /= 1.0f + 0.1f * logf(1.0f / freq_scale);
    }
    uint32_t *comp_counts = compressed ? xcalloc(n_tokens, sizeof(comp_counts[0])) : NULL;
    uint32_t *index_counts = ratio == 4 ? xcalloc(n_tokens, sizeof(index_counts[0])) : NULL;
    const bool qkv_rms_fused = !metal_graph_use_reference_qkv_norm();
```

<｜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
ge layer=%u pos=%u tokens=%u %s=%.3f ms\n",
            il,
            pos0,
            n_tokens,
            stage,
            (now - *stage_t0) * 1000.0);
    *stage_t0 = now;
    return ds4_gpu_begin_commands() != 0;
}

static bool metal_graph_encode_layer_attention_batch(
        ds4_gpu_graph  *g,
        const ds4_model        *model,
        const ds4_layer_weights *layer,
        uint32_t                il,
        uint32_t                pos0,
        uint32_t                n_tokens) {
    if (n_tokens == 0 || n_tokens > g->prefill_cap) return false;

    const uint64_t hc_dim = (uint64_t)DS4_N_HC * DS4_N_EMBD;
    const uint64_t mix_hc = 2ull * DS4_N_HC + (uint64_t)DS4_N_HC * DS4_N_HC;
    const uint64_t q_rank = layer->attn_q_a->dim[1];
    const uint64_t q_dim = (uint64_t)DS4_N_HEAD * DS4_N_HEAD_DIM;
    const uint32_t n_groups = DS4_N_OUT_GROUP;
    const uint32_t group_heads = DS4_N_HEAD / n_groups;
    const uint32_t group_dim = DS4_N_HEAD_DIM * group_heads;
    const uint32_t rank = DS4_N_LORA_O;
    const uint32_t ratio = ds4_layer_compress_ratio(il);
    const bool compressed = ratio != 0;
    const bool zero_prefix = pos0 == 0;
    const bool index_stage_profile = getenv("DS4_METAL_INDEXER_STAGE_PROFILE") != NULL;
    const bool layer_stage_profile = getenv("DS4_METAL_LAYER_STAGE_PROFILE") != NULL;
    const bool q_stage_profile = getenv("DS4_METAL_Q_STAGE_PROFILE") != NULL;
    double layer_stage_t0 = layer_stage_profile ? now_sec() : 0.0;
    double q_stage_t0 = q_stage_profile ? now_sec() : 0.0;
#define DS4_METAL_PROFILE_ATTN_STAGE(name) do { \
        if (ok && layer_stage_profile) { \
            ok = metal_graph_layer_stage_profile_boundary("attn", (name), il, pos0, n_tokens, &layer_stage_t0); \
        } \
    } while (0)
#define DS4_METAL_PROFILE_Q_STAGE(name) do { \
        if (ok && q_stage_profile) { \
            ok = metal_graph_q_stage_profile_boundary((name), il, pos0, n_tokens, &q_stage_t0); \
        } \
    } while (0)
    const float freq_base = layer_rope_freq_base(il);
    const float freq_scale = layer_rope_freq_scale(il);
    const float ext_factor = compressed && DS4_ROPE_SCALE_FACTOR > 1.0f ? 1.0f : 0.0f;
    float attn_factor = 1.0f;
    if (ext_factor != 0.0f && freq_scale > 0.0f) {
        attn_factor /= 1.0f + 0.1f * logf(1.0f / freq_scale);
    }
    uint32_t *comp_counts = compressed ? xcalloc(n_tokens, sizeof(comp_counts[0])) : NULL;
    uint32_t *index_counts = ratio == 4 ? xcalloc(n_tokens, sizeof(index_counts[0])) : NULL;
    const bool qkv_rms_fused = !metal_graph_use_reference_qkv_norm();
```<｜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
ge layer=%u pos=%u tokens=%u %s=%.3f ms\n",
            il,
            pos0,
            n_tokens,
            stage,
            (now - *stage_t0) * 1000.0);
    *stage_t0 = now;
    return ds4_gpu_begin_commands() != 0;
}

static bool metal_graph_encode_layer_attention_batch(
        ds4_gpu_graph  *g,
        const ds4_model        *model,
        const ds4_layer_weights *layer,
        uint32_t                il,
        uint32_t                pos0,
        uint32_t                n_tokens) {
    if (n_tokens == 0 || n_tokens > g->prefill_cap) return false;

    const uint64_t hc_dim = (uint64_t)DS4_N_HC * DS4_N_EMBD;
    const uint64_t mix_hc = 2ull * DS4_N_HC + (uint64_t)DS4_N_HC * DS4_N_HC;
    const uint64_t q_rank = layer->attn_q_a->dim[1];
    const uint64_t q_dim = (uint64_t)DS4_N_HEAD * DS4_N_HEAD_DIM;
    const uint32_t n_groups = DS4_N_OUT_GROUP;
    const uint32_t group_heads = DS4_N_HEAD / n_groups;
    const uint32_t group_dim = DS4_N_HEAD_DIM * group_heads;
    const uint32_t rank = DS4_N_LORA_O;
    const uint32_t ratio = ds4_layer_compress_ratio(il);
    const bool compressed = ratio != 0;
    const bool zero_prefix = pos0 == 0;
    const bool index_stage_profile = getenv("DS4_METAL_INDEXER_STAGE_PROFILE") != NULL;
    const bool layer_stage_profile = getenv("DS4_METAL_LAYER_STAGE_PROFILE") != NULL;
    const bool q_stage_profile = getenv("DS4_METAL_Q_STAGE_PROFILE") != NULL;
    double layer_stage_t0 = layer_stage_profile ? now_sec() : 0.0;
    double q_stage_t0 = q_stage_profile ? now_sec() : 0.0;
#define DS4_METAL_PROFILE_ATTN_STAGE(name) do { \
        if (ok && layer_stage_profile) { \
            ok = metal_graph_layer_stage_profile_boundary("attn", (name), il, pos0, n_tokens, &layer_stage_t0); \
        } \
    } while (0)
#define DS4_METAL_PROFILE_Q_STAGE(name) do { \
        if (ok && q_stage_profile) { \
            ok = metal_graph_q_stage_profile_boundary((name), il, pos0, n_tokens, &q_stage_t0); \
        } \
    } while (0)
    const float freq_base = layer_rope_freq_base(il);
    const float freq_scale = layer_rope_freq_scale(il);
    const float ext_factor = compressed && DS4_ROPE_SCALE_FACTOR > 1.0f ? 1.0f : 0.0f;
    float attn_factor = 1.0f;
    if (ext_factor != 0.0f && freq_scale > 0.0f) {
        attn_factor /= 1.0f + 0.1f * logf(1.0f / freq_scale);
    }
    uint32_t *comp_counts = compressed ? xcalloc(n_tokens, sizeof(comp_counts[0])) : NULL;
    uint32_t *index_counts = ratio == 4 ? xcalloc(n_tokens, sizeof(index_counts[0])) : NULL;
    const bool qkv_rms_fused = !metal_graph_use_reference_qkv_norm();
```

<｜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
ge layer=%u pos=%u tokens=%u %s=%.3f ms\n",
            il,
            pos0,
            n_tokens,
            stage,
            (now - *stage_t0) * 1000.0);
    *stage_t0 = now;
    return ds4_gpu_begin_commands() != 0;
}

static bool metal_graph_encode_layer_attention_batch(
        ds4_gpu_graph  *g,
        const ds4_model        *model,
        const ds4_layer_weights *layer,
        uint32_t                il,
        uint32_t                pos0,
        uint32_t                n_tokens) {
    if (n_tokens == 0 || n_tokens > g->prefill_cap) return false;

    const uint64_t hc_dim = (uint64_t)DS4_N_HC * DS4_N_EMBD;
    const uint64_t mix_hc = 2ull * DS4_N_HC + (uint64_t)DS4_N_HC * DS4_N_HC;
    const uint64_t q_rank = layer->attn_q_a->dim[1];
    const uint64_t q_dim = (uint64_t)DS4_N_HEAD * DS4_N_HEAD_DIM;
    const uint32_t n_groups = DS4_N_OUT_GROUP;
    const uint32_t group_heads = DS4_N_HEAD / n_groups;
    const uint32_t group_dim = DS4_N_HEAD_DIM * group_heads;
    const uint32_t rank = DS4_N_LORA_O;
    const uint32_t ratio = ds4_layer_compress_ratio(il);
    const bool compressed = ratio != 0;
    const bool zero_prefix = pos0 == 0;
    const bool index_stage_profile = getenv("DS4_METAL_INDEXER_STAGE_PROFILE") != NULL;
    const bool layer_stage_profile = getenv("DS4_METAL_LAYER_STAGE_PROFILE") != NULL;
    const bool q_stage_profile = getenv("DS4_METAL_Q_STAGE_PROFILE") != NULL;
    double layer_stage_t0 = layer_stage_profile ? now_sec() : 0.0;
    double q_stage_t0 = q_stage_profile ? now_sec() : 0.0;
#define DS4_METAL_PROFILE_ATTN_STAGE(name) do { \
        if (ok && layer_stage_profile) { \
            ok = metal_graph_layer_stage_profile_boundary("attn", (name), il, pos0, n_tokens, &layer_stage_t0); \
        } \
    } while (0)
#define DS4_METAL_PROFILE_Q_STAGE(name) do { \
        if (ok && q_stage_profile) { \
            ok = metal_graph_q_stage_profile_boundary((name), il, pos0, n_tokens, &q_stage_t0); \
        } \
    } while (0)
    const float freq_base = layer_rope_freq_base(il);
    const float freq_scale = layer_rope_freq_scale(il);
    const float ext_factor = compressed && DS4_ROPE_SCALE_FACTOR > 1.0f ? 1.0f : 0.0f;
    float attn_factor = 1.0f;
    if (ext_factor != 0.0f && freq_scale > 0.0f) {
        attn_factor /= 1.0f + 0.1f * logf(1.0f / freq_scale);
    }
    uint32_t *comp_counts = compressed ? xcalloc(n_tokens, sizeof(comp_counts[0])) : NULL;
    uint32_t *index_counts = ratio == 4 ? xcalloc(n_tokens, sizeof(index_counts[0])) : NULL;
    const bool qkv_rms_fused = !metal_graph_use_reference_qkv_norm();
```<｜Assistant｜><think>