[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_server.c

```c
), .name = xstrdup("bash"), .arguments = xstrdup("{}")};
    tool_calls_push(&a.calls, keep);
    chat_msgs_push(&msgs, a);
    chat_msg b = {0};
    b.role = xstrdup("assistant");
    tool_call drop = {.id = xstrdup("call_drop"), .name = xstrdup("bash"), .arguments = xstrdup("{}")};
    tool_calls_push(&b.calls, drop);
    chat_msgs_push(&msgs, b);
    tool_replay_stats stats = {0};
    tool_memory_attach_to_messages(&dst, &msgs, &stats);
    TEST_ASSERT(msgs.v[0].calls.raw_dsml != NULL);
    TEST_ASSERT(msgs.v[1].calls.raw_dsml == NULL);
    TEST_ASSERT(stats.disk == 1);
    TEST_ASSERT(stats.canonical == 1);
    TEST_ASSERT(stats.missing_ids == 1);
    TEST_ASSERT(strstr(msgs.v[0].calls.raw_dsml, "pwd") != NULL);
    TEST_ASSERT(strstr(msgs.v[0].calls.raw_dsml, "zzzz") == NULL);

    chat_msgs_free(&msgs);
    if (fp) fclose(fp);
    tool_memory_free(&src.tool_mem);
    tool_memory_free(&dst.tool_mem);
    pthread_mutex_destroy(&src.tool_mu);
    pthread_mutex_destroy(&dst.tool_mu);
}

static void test_kv_tool_map_restores_before_prompt_render(void) {
    char tmpl[] = "/tmp/ds4-kv-tool-map-test.XXXXXX";
    char *dir = mkdtemp(tmpl);
    TEST_ASSERT(dir != NULL);
    if (!dir) return;

    const char *sha = "3333333333333333333333333333333333333333";
    char name[44];
    snprintf(name, sizeof(name), "%.40s.kv", sha);
    char *path = path_join(dir, name);
    const char *dsml =
        "\n\n<｜DSML｜tool_calls>\n"
        "<｜DSML｜invoke name=\"bash\">\n"
        "<｜DSML｜parameter name=\"command\" string=\"true\">echo exact</｜DSML｜parameter>\n"
        "</｜DSML｜invoke>\n"
        "</｜DSML｜tool_calls>";
    const char *text = dsml;

    server src = {0};
    pthread_mutex_init(&src.tool_mu, NULL);
    tool_memory_put(&src, "call_disk", dsml);

    FILE *fp = fopen(path, "wb");
    TEST_ASSERT(fp != NULL);
    if (fp) {
        uint8_t h[KV_CACHE_FIXED_HEADER];
        kv_fill_header(h, 2, KV_REASON_CONTINUED, KV_EXT_TOOL_MAP, 512, 0, 32768, 100, 100, 0);
        uint8_t text_len[4];
        le_put32(text_len, (uint32_t)strlen(text));
        TEST_ASSERT(fwrite(h, 1, sizeof(h), fp) == sizeof(h));
        TEST_ASSERT(fwrite(text_len, 1, sizeof(text_len), fp) == sizeof(text_len));
        TEST_ASSERT(fwrite(text, 1, strlen(text), fp) == strlen(text));
        uint64_t ignored = 0;
        TEST_ASSERT(kv_tool_map_write(&src, fp, dsml, &ignored));
        TEST_ASSERT(fclose(fp) == 0);
    }

    server dst = {0};
    pthread_mutex_init(&dst.tool_mu, NULL);
    dst.kv.enabled = true;
    dst.kv.dir = xstrdup(dir);
```

<｜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_server.c

```c
), .name = xstrdup("bash"), .arguments = xstrdup("{}")};
    tool_calls_push(&a.calls, keep);
    chat_msgs_push(&msgs, a);
    chat_msg b = {0};
    b.role = xstrdup("assistant");
    tool_call drop = {.id = xstrdup("call_drop"), .name = xstrdup("bash"), .arguments = xstrdup("{}")};
    tool_calls_push(&b.calls, drop);
    chat_msgs_push(&msgs, b);
    tool_replay_stats stats = {0};
    tool_memory_attach_to_messages(&dst, &msgs, &stats);
    TEST_ASSERT(msgs.v[0].calls.raw_dsml != NULL);
    TEST_ASSERT(msgs.v[1].calls.raw_dsml == NULL);
    TEST_ASSERT(stats.disk == 1);
    TEST_ASSERT(stats.canonical == 1);
    TEST_ASSERT(stats.missing_ids == 1);
    TEST_ASSERT(strstr(msgs.v[0].calls.raw_dsml, "pwd") != NULL);
    TEST_ASSERT(strstr(msgs.v[0].calls.raw_dsml, "zzzz") == NULL);

    chat_msgs_free(&msgs);
    if (fp) fclose(fp);
    tool_memory_free(&src.tool_mem);
    tool_memory_free(&dst.tool_mem);
    pthread_mutex_destroy(&src.tool_mu);
    pthread_mutex_destroy(&dst.tool_mu);
}

static void test_kv_tool_map_restores_before_prompt_render(void) {
    char tmpl[] = "/tmp/ds4-kv-tool-map-test.XXXXXX";
    char *dir = mkdtemp(tmpl);
    TEST_ASSERT(dir != NULL);
    if (!dir) return;

    const char *sha = "3333333333333333333333333333333333333333";
    char name[44];
    snprintf(name, sizeof(name), "%.40s.kv", sha);
    char *path = path_join(dir, name);
    const char *dsml =
        "\n\n<｜DSML｜tool_calls>\n"
        "<｜DSML｜invoke name=\"bash\">\n"
        "<｜DSML｜parameter name=\"command\" string=\"true\">echo exact</｜DSML｜parameter>\n"
        "</｜DSML｜invoke>\n"
        "</｜DSML｜tool_calls>";
    const char *text = dsml;

    server src = {0};
    pthread_mutex_init(&src.tool_mu, NULL);
    tool_memory_put(&src, "call_disk", dsml);

    FILE *fp = fopen(path, "wb");
    TEST_ASSERT(fp != NULL);
    if (fp) {
        uint8_t h[KV_CACHE_FIXED_HEADER];
        kv_fill_header(h, 2, KV_REASON_CONTINUED, KV_EXT_TOOL_MAP, 512, 0, 32768, 100, 100, 0);
        uint8_t text_len[4];
        le_put32(text_len, (uint32_t)strlen(text));
        TEST_ASSERT(fwrite(h, 1, sizeof(h), fp) == sizeof(h));
        TEST_ASSERT(fwrite(text_len, 1, sizeof(text_len), fp) == sizeof(text_len));
        TEST_ASSERT(fwrite(text, 1, strlen(text), fp) == strlen(text));
        uint64_t ignored = 0;
        TEST_ASSERT(kv_tool_map_write(&src, fp, dsml, &ignored));
        TEST_ASSERT(fclose(fp) == 0);
    }

    server dst = {0};
    pthread_mutex_init(&dst.tool_mu, NULL);
    dst.kv.enabled = true;
    dst.kv.dir = xstrdup(dir);
```<｜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_server.c

```c
), .name = xstrdup("bash"), .arguments = xstrdup("{}")};
    tool_calls_push(&a.calls, keep);
    chat_msgs_push(&msgs, a);
    chat_msg b = {0};
    b.role = xstrdup("assistant");
    tool_call drop = {.id = xstrdup("call_drop"), .name = xstrdup("bash"), .arguments = xstrdup("{}")};
    tool_calls_push(&b.calls, drop);
    chat_msgs_push(&msgs, b);
    tool_replay_stats stats = {0};
    tool_memory_attach_to_messages(&dst, &msgs, &stats);
    TEST_ASSERT(msgs.v[0].calls.raw_dsml != NULL);
    TEST_ASSERT(msgs.v[1].calls.raw_dsml == NULL);
    TEST_ASSERT(stats.disk == 1);
    TEST_ASSERT(stats.canonical == 1);
    TEST_ASSERT(stats.missing_ids == 1);
    TEST_ASSERT(strstr(msgs.v[0].calls.raw_dsml, "pwd") != NULL);
    TEST_ASSERT(strstr(msgs.v[0].calls.raw_dsml, "zzzz") == NULL);

    chat_msgs_free(&msgs);
    if (fp) fclose(fp);
    tool_memory_free(&src.tool_mem);
    tool_memory_free(&dst.tool_mem);
    pthread_mutex_destroy(&src.tool_mu);
    pthread_mutex_destroy(&dst.tool_mu);
}

static void test_kv_tool_map_restores_before_prompt_render(void) {
    char tmpl[] = "/tmp/ds4-kv-tool-map-test.XXXXXX";
    char *dir = mkdtemp(tmpl);
    TEST_ASSERT(dir != NULL);
    if (!dir) return;

    const char *sha = "3333333333333333333333333333333333333333";
    char name[44];
    snprintf(name, sizeof(name), "%.40s.kv", sha);
    char *path = path_join(dir, name);
    const char *dsml =
        "\n\n<｜DSML｜tool_calls>\n"
        "<｜DSML｜invoke name=\"bash\">\n"
        "<｜DSML｜parameter name=\"command\" string=\"true\">echo exact</｜DSML｜parameter>\n"
        "</｜DSML｜invoke>\n"
        "</｜DSML｜tool_calls>";
    const char *text = dsml;

    server src = {0};
    pthread_mutex_init(&src.tool_mu, NULL);
    tool_memory_put(&src, "call_disk", dsml);

    FILE *fp = fopen(path, "wb");
    TEST_ASSERT(fp != NULL);
    if (fp) {
        uint8_t h[KV_CACHE_FIXED_HEADER];
        kv_fill_header(h, 2, KV_REASON_CONTINUED, KV_EXT_TOOL_MAP, 512, 0, 32768, 100, 100, 0);
        uint8_t text_len[4];
        le_put32(text_len, (uint32_t)strlen(text));
        TEST_ASSERT(fwrite(h, 1, sizeof(h), fp) == sizeof(h));
        TEST_ASSERT(fwrite(text_len, 1, sizeof(text_len), fp) == sizeof(text_len));
        TEST_ASSERT(fwrite(text, 1, strlen(text), fp) == strlen(text));
        uint64_t ignored = 0;
        TEST_ASSERT(kv_tool_map_write(&src, fp, dsml, &ignored));
        TEST_ASSERT(fclose(fp) == 0);
    }

    server dst = {0};
    pthread_mutex_init(&dst.tool_mu, NULL);
    dst.kv.enabled = true;
    dst.kv.dir = xstrdup(dir);
```

<｜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_server.c

```c
), .name = xstrdup("bash"), .arguments = xstrdup("{}")};
    tool_calls_push(&a.calls, keep);
    chat_msgs_push(&msgs, a);
    chat_msg b = {0};
    b.role = xstrdup("assistant");
    tool_call drop = {.id = xstrdup("call_drop"), .name = xstrdup("bash"), .arguments = xstrdup("{}")};
    tool_calls_push(&b.calls, drop);
    chat_msgs_push(&msgs, b);
    tool_replay_stats stats = {0};
    tool_memory_attach_to_messages(&dst, &msgs, &stats);
    TEST_ASSERT(msgs.v[0].calls.raw_dsml != NULL);
    TEST_ASSERT(msgs.v[1].calls.raw_dsml == NULL);
    TEST_ASSERT(stats.disk == 1);
    TEST_ASSERT(stats.canonical == 1);
    TEST_ASSERT(stats.missing_ids == 1);
    TEST_ASSERT(strstr(msgs.v[0].calls.raw_dsml, "pwd") != NULL);
    TEST_ASSERT(strstr(msgs.v[0].calls.raw_dsml, "zzzz") == NULL);

    chat_msgs_free(&msgs);
    if (fp) fclose(fp);
    tool_memory_free(&src.tool_mem);
    tool_memory_free(&dst.tool_mem);
    pthread_mutex_destroy(&src.tool_mu);
    pthread_mutex_destroy(&dst.tool_mu);
}

static void test_kv_tool_map_restores_before_prompt_render(void) {
    char tmpl[] = "/tmp/ds4-kv-tool-map-test.XXXXXX";
    char *dir = mkdtemp(tmpl);
    TEST_ASSERT(dir != NULL);
    if (!dir) return;

    const char *sha = "3333333333333333333333333333333333333333";
    char name[44];
    snprintf(name, sizeof(name), "%.40s.kv", sha);
    char *path = path_join(dir, name);
    const char *dsml =
        "\n\n<｜DSML｜tool_calls>\n"
        "<｜DSML｜invoke name=\"bash\">\n"
        "<｜DSML｜parameter name=\"command\" string=\"true\">echo exact</｜DSML｜parameter>\n"
        "</｜DSML｜invoke>\n"
        "</｜DSML｜tool_calls>";
    const char *text = dsml;

    server src = {0};
    pthread_mutex_init(&src.tool_mu, NULL);
    tool_memory_put(&src, "call_disk", dsml);

    FILE *fp = fopen(path, "wb");
    TEST_ASSERT(fp != NULL);
    if (fp) {
        uint8_t h[KV_CACHE_FIXED_HEADER];
        kv_fill_header(h, 2, KV_REASON_CONTINUED, KV_EXT_TOOL_MAP, 512, 0, 32768, 100, 100, 0);
        uint8_t text_len[4];
        le_put32(text_len, (uint32_t)strlen(text));
        TEST_ASSERT(fwrite(h, 1, sizeof(h), fp) == sizeof(h));
        TEST_ASSERT(fwrite(text_len, 1, sizeof(text_len), fp) == sizeof(text_len));
        TEST_ASSERT(fwrite(text, 1, strlen(text), fp) == strlen(text));
        uint64_t ignored = 0;
        TEST_ASSERT(kv_tool_map_write(&src, fp, dsml, &ignored));
        TEST_ASSERT(fclose(fp) == 0);
    }

    server dst = {0};
    pthread_mutex_init(&dst.tool_mu, NULL);
    dst.kv.enabled = true;
    dst.kv.dir = xstrdup(dir);
```<｜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_server.c

```c
&ignored));
        TEST_ASSERT(fclose(fp) == 0);
    }

    server dst = {0};
    pthread_mutex_init(&dst.tool_mu, NULL);
    dst.kv.enabled = true;
    dst.kv.dir = xstrdup(dir);
    dst.kv.opt = kv_cache_default_options();

    chat_msgs msgs = {0};
    chat_msg a = {0};
    a.role = xstrdup("assistant");
    tool_call tc = {0};
    tc.id = xstrdup("call_disk");
    tc.name = xstrdup("bash");
    tc.arguments = xstrdup("{\"command\":\"echo canonical\"}");
    tool_calls_push(&a.calls, tc);
    chat_msgs_push(&msgs, a);

    kv_cache_restore_tool_memory_for_messages(&dst, &msgs);
    tool_replay_stats stats = {0};
    tool_memory_attach_to_messages(&dst, &msgs, &stats);
    TEST_ASSERT(msgs.v[0].calls.raw_dsml != NULL);
    TEST_ASSERT(stats.disk == 1);
    TEST_ASSERT(stats.canonical == 0);
    char *prompt = render_chat_prompt_text(&msgs, NULL, NULL, DS4_THINK_HIGH);
    TEST_ASSERT(strstr(prompt, "echo exact") != NULL);
    TEST_ASSERT(strstr(prompt, "echo canonical") == NULL);

    free(prompt);
    chat_msgs_free(&msgs);
    kv_cache_close(&dst.kv);
    tool_memory_free(&src.tool_mem);
    tool_memory_free(&dst.tool_mem);
    pthread_mutex_destroy(&src.tool_mu);
    pthread_mutex_destroy(&dst.tool_mu);
    unlink(path);
    free(path);
    rmdir(dir);
}

static void test_kv_cache_eviction_values_fresh_snapshots(void) {
    char tmpl[] = "/tmp/ds4-kv-evict-test.XXXXXX";
    char *dir = mkdtemp(tmpl);
    TEST_ASSERT(dir != NULL);
    if (!dir) return;

    const char *old_sha = "1111111111111111111111111111111111111111";
    const char *new_sha = "2222222222222222222222222222222222222222";
    uint64_t now = (uint64_t)time(NULL);
    test_kv_stub_file(dir, old_sha, KV_REASON_UNKNOWN, 512, 0, now, 4096);
    test_kv_stub_file(dir, new_sha, KV_REASON_UNKNOWN, 2048, 0, now, 2048);

    char old_name[44], new_name[44];
    snprintf(old_name, sizeof(old_name), "%.40s.kv", old_sha);
    snprintf(new_name, sizeof(new_name), "%.40s.kv", new_sha);
    char *old_path = path_join(dir, old_name);
    char *new_path = path_join(dir, new_name);

    kv_disk_cache kc = {0};
    kc.enabled = true;
    kc.dir = xstrdup(dir);
    kc.opt = kv_cache_default_options();
    kc.budget_bytes = (KV_CACHE_FIXED_HEADER + 4u + 2048u) + 16u;
    kv_cache_evict(&kc, NULL, NULL);

    TEST_ASSERT(access(old_path, F_OK) != 0);
    TEST_ASSERT(access(new_path, F_OK) == 0);

    kv_cache_close(&kc);
    unlink(old_path);
    unlink(new_path);
    free(old_path);
    free(new_path);
    rmdir(dir);
}

static void test_kv_cache_eviction_protects_current_store(void) {
```

<｜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_server.c

```c
&ignored));
        TEST_ASSERT(fclose(fp) == 0);
    }

    server dst = {0};
    pthread_mutex_init(&dst.tool_mu, NULL);
    dst.kv.enabled = true;
    dst.kv.dir = xstrdup(dir);
    dst.kv.opt = kv_cache_default_options();

    chat_msgs msgs = {0};
    chat_msg a = {0};
    a.role = xstrdup("assistant");
    tool_call tc = {0};
    tc.id = xstrdup("call_disk");
    tc.name = xstrdup("bash");
    tc.arguments = xstrdup("{\"command\":\"echo canonical\"}");
    tool_calls_push(&a.calls, tc);
    chat_msgs_push(&msgs, a);

    kv_cache_restore_tool_memory_for_messages(&dst, &msgs);
    tool_replay_stats stats = {0};
    tool_memory_attach_to_messages(&dst, &msgs, &stats);
    TEST_ASSERT(msgs.v[0].calls.raw_dsml != NULL);
    TEST_ASSERT(stats.disk == 1);
    TEST_ASSERT(stats.canonical == 0);
    char *prompt = render_chat_prompt_text(&msgs, NULL, NULL, DS4_THINK_HIGH);
    TEST_ASSERT(strstr(prompt, "echo exact") != NULL);
    TEST_ASSERT(strstr(prompt, "echo canonical") == NULL);

    free(prompt);
    chat_msgs_free(&msgs);
    kv_cache_close(&dst.kv);
    tool_memory_free(&src.tool_mem);
    tool_memory_free(&dst.tool_mem);
    pthread_mutex_destroy(&src.tool_mu);
    pthread_mutex_destroy(&dst.tool_mu);
    unlink(path);
    free(path);
    rmdir(dir);
}

static void test_kv_cache_eviction_values_fresh_snapshots(void) {
    char tmpl[] = "/tmp/ds4-kv-evict-test.XXXXXX";
    char *dir = mkdtemp(tmpl);
    TEST_ASSERT(dir != NULL);
    if (!dir) return;

    const char *old_sha = "1111111111111111111111111111111111111111";
    const char *new_sha = "2222222222222222222222222222222222222222";
    uint64_t now = (uint64_t)time(NULL);
    test_kv_stub_file(dir, old_sha, KV_REASON_UNKNOWN, 512, 0, now, 4096);
    test_kv_stub_file(dir, new_sha, KV_REASON_UNKNOWN, 2048, 0, now, 2048);

    char old_name[44], new_name[44];
    snprintf(old_name, sizeof(old_name), "%.40s.kv", old_sha);
    snprintf(new_name, sizeof(new_name), "%.40s.kv", new_sha);
    char *old_path = path_join(dir, old_name);
    char *new_path = path_join(dir, new_name);

    kv_disk_cache kc = {0};
    kc.enabled = true;
    kc.dir = xstrdup(dir);
    kc.opt = kv_cache_default_options();
    kc.budget_bytes = (KV_CACHE_FIXED_HEADER + 4u + 2048u) + 16u;
    kv_cache_evict(&kc, NULL, NULL);

    TEST_ASSERT(access(old_path, F_OK) != 0);
    TEST_ASSERT(access(new_path, F_OK) == 0);

    kv_cache_close(&kc);
    unlink(old_path);
    unlink(new_path);
    free(old_path);
    free(new_path);
    rmdir(dir);
}

static void test_kv_cache_eviction_protects_current_store(void) {
```<｜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_server.c

```c
&ignored));
        TEST_ASSERT(fclose(fp) == 0);
    }

    server dst = {0};
    pthread_mutex_init(&dst.tool_mu, NULL);
    dst.kv.enabled = true;
    dst.kv.dir = xstrdup(dir);
    dst.kv.opt = kv_cache_default_options();

    chat_msgs msgs = {0};
    chat_msg a = {0};
    a.role = xstrdup("assistant");
    tool_call tc = {0};
    tc.id = xstrdup("call_disk");
    tc.name = xstrdup("bash");
    tc.arguments = xstrdup("{\"command\":\"echo canonical\"}");
    tool_calls_push(&a.calls, tc);
    chat_msgs_push(&msgs, a);

    kv_cache_restore_tool_memory_for_messages(&dst, &msgs);
    tool_replay_stats stats = {0};
    tool_memory_attach_to_messages(&dst, &msgs, &stats);
    TEST_ASSERT(msgs.v[0].calls.raw_dsml != NULL);
    TEST_ASSERT(stats.disk == 1);
    TEST_ASSERT(stats.canonical == 0);
    char *prompt = render_chat_prompt_text(&msgs, NULL, NULL, DS4_THINK_HIGH);
    TEST_ASSERT(strstr(prompt, "echo exact") != NULL);
    TEST_ASSERT(strstr(prompt, "echo canonical") == NULL);

    free(prompt);
    chat_msgs_free(&msgs);
    kv_cache_close(&dst.kv);
    tool_memory_free(&src.tool_mem);
    tool_memory_free(&dst.tool_mem);
    pthread_mutex_destroy(&src.tool_mu);
    pthread_mutex_destroy(&dst.tool_mu);
    unlink(path);
    free(path);
    rmdir(dir);
}

static void test_kv_cache_eviction_values_fresh_snapshots(void) {
    char tmpl[] = "/tmp/ds4-kv-evict-test.XXXXXX";
    char *dir = mkdtemp(tmpl);
    TEST_ASSERT(dir != NULL);
    if (!dir) return;

    const char *old_sha = "1111111111111111111111111111111111111111";
    const char *new_sha = "2222222222222222222222222222222222222222";
    uint64_t now = (uint64_t)time(NULL);
    test_kv_stub_file(dir, old_sha, KV_REASON_UNKNOWN, 512, 0, now, 4096);
    test_kv_stub_file(dir, new_sha, KV_REASON_UNKNOWN, 2048, 0, now, 2048);

    char old_name[44], new_name[44];
    snprintf(old_name, sizeof(old_name), "%.40s.kv", old_sha);
    snprintf(new_name, sizeof(new_name), "%.40s.kv", new_sha);
    char *old_path = path_join(dir, old_name);
    char *new_path = path_join(dir, new_name);

    kv_disk_cache kc = {0};
    kc.enabled = true;
    kc.dir = xstrdup(dir);
    kc.opt = kv_cache_default_options();
    kc.budget_bytes = (KV_CACHE_FIXED_HEADER + 4u + 2048u) + 16u;
    kv_cache_evict(&kc, NULL, NULL);

    TEST_ASSERT(access(old_path, F_OK) != 0);
    TEST_ASSERT(access(new_path, F_OK) == 0);

    kv_cache_close(&kc);
    unlink(old_path);
    unlink(new_path);
    free(old_path);
    free(new_path);
    rmdir(dir);
}

static void test_kv_cache_eviction_protects_current_store(void) {
```

<｜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_server.c

```c
&ignored));
        TEST_ASSERT(fclose(fp) == 0);
    }

    server dst = {0};
    pthread_mutex_init(&dst.tool_mu, NULL);
    dst.kv.enabled = true;
    dst.kv.dir = xstrdup(dir);
    dst.kv.opt = kv_cache_default_options();

    chat_msgs msgs = {0};
    chat_msg a = {0};
    a.role = xstrdup("assistant");
    tool_call tc = {0};
    tc.id = xstrdup("call_disk");
    tc.name = xstrdup("bash");
    tc.arguments = xstrdup("{\"command\":\"echo canonical\"}");
    tool_calls_push(&a.calls, tc);
    chat_msgs_push(&msgs, a);

    kv_cache_restore_tool_memory_for_messages(&dst, &msgs);
    tool_replay_stats stats = {0};
    tool_memory_attach_to_messages(&dst, &msgs, &stats);
    TEST_ASSERT(msgs.v[0].calls.raw_dsml != NULL);
    TEST_ASSERT(stats.disk == 1);
    TEST_ASSERT(stats.canonical == 0);
    char *prompt = render_chat_prompt_text(&msgs, NULL, NULL, DS4_THINK_HIGH);
    TEST_ASSERT(strstr(prompt, "echo exact") != NULL);
    TEST_ASSERT(strstr(prompt, "echo canonical") == NULL);

    free(prompt);
    chat_msgs_free(&msgs);
    kv_cache_close(&dst.kv);
    tool_memory_free(&src.tool_mem);
    tool_memory_free(&dst.tool_mem);
    pthread_mutex_destroy(&src.tool_mu);
    pthread_mutex_destroy(&dst.tool_mu);
    unlink(path);
    free(path);
    rmdir(dir);
}

static void test_kv_cache_eviction_values_fresh_snapshots(void) {
    char tmpl[] = "/tmp/ds4-kv-evict-test.XXXXXX";
    char *dir = mkdtemp(tmpl);
    TEST_ASSERT(dir != NULL);
    if (!dir) return;

    const char *old_sha = "1111111111111111111111111111111111111111";
    const char *new_sha = "2222222222222222222222222222222222222222";
    uint64_t now = (uint64_t)time(NULL);
    test_kv_stub_file(dir, old_sha, KV_REASON_UNKNOWN, 512, 0, now, 4096);
    test_kv_stub_file(dir, new_sha, KV_REASON_UNKNOWN, 2048, 0, now, 2048);

    char old_name[44], new_name[44];
    snprintf(old_name, sizeof(old_name), "%.40s.kv", old_sha);
    snprintf(new_name, sizeof(new_name), "%.40s.kv", new_sha);
    char *old_path = path_join(dir, old_name);
    char *new_path = path_join(dir, new_name);

    kv_disk_cache kc = {0};
    kc.enabled = true;
    kc.dir = xstrdup(dir);
    kc.opt = kv_cache_default_options();
    kc.budget_bytes = (KV_CACHE_FIXED_HEADER + 4u + 2048u) + 16u;
    kv_cache_evict(&kc, NULL, NULL);

    TEST_ASSERT(access(old_path, F_OK) != 0);
    TEST_ASSERT(access(new_path, F_OK) == 0);

    kv_cache_close(&kc);
    unlink(old_path);
    unlink(new_path);
    free(old_path);
    free(new_path);
    rmdir(dir);
}

static void test_kv_cache_eviction_protects_current_store(void) {
```<｜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_server.c

```c
close(&kc);
    unlink(old_path);
    unlink(new_path);
    free(old_path);
    free(new_path);
    rmdir(dir);
}

static void test_kv_cache_eviction_protects_current_store(void) {
    char tmpl[] = "/tmp/ds4-kv-current-store-evict-test.XXXXXX";
    char *dir = mkdtemp(tmpl);
    TEST_ASSERT(dir != NULL);
    if (!dir) return;

    const char *old_sha = "1111111111111111111111111111111111111111";
    const char *new_sha = "2222222222222222222222222222222222222222";
    uint64_t now = (uint64_t)time(NULL);
    test_kv_stub_file(dir, old_sha, KV_REASON_COLD, 4096, 0, now, 2048);
    test_kv_stub_file(dir, new_sha, KV_REASON_CONTINUED, 2048, 0, now, 4096);

    char old_name[44], new_name[44];
    snprintf(old_name, sizeof(old_name), "%.40s.kv", old_sha);
    snprintf(new_name, sizeof(new_name), "%.40s.kv", new_sha);
    char *old_path = path_join(dir, old_name);
    char *new_path = path_join(dir, new_name);

    kv_disk_cache kc = {0};
    kc.enabled = true;
    kc.dir = xstrdup(dir);
    kc.opt = kv_cache_default_options();
    kc.budget_bytes = (KV_CACHE_FIXED_HEADER + 4u + 4096u) + 16u;
    kv_cache_evict(&kc, NULL, new_sha);

    TEST_ASSERT(access(old_path, F_OK) != 0);
    TEST_ASSERT(access(new_path, F_OK) == 0);

    kv_cache_close(&kc);
    unlink(old_path);
    unlink(new_path);
    free(old_path);
    free(new_path);
    rmdir(dir);
}

static void test_kv_cache_eviction_does_not_protect_oversize_current_store(void) {
    char tmpl[] = "/tmp/ds4-kv-oversize-store-evict-test.XXXXXX";
    char *dir = mkdtemp(tmpl);
    TEST_ASSERT(dir != NULL);
    if (!dir) return;

    const char *old_sha = "1111111111111111111111111111111111111111";
    const char *new_sha = "2222222222222222222222222222222222222222";
    uint64_t now = (uint64_t)time(NULL);
    test_kv_stub_file(dir, old_sha, KV_REASON_COLD, 4096, 0, now, 1024);
    test_kv_stub_file(dir, new_sha, KV_REASON_CONTINUED, 4096, 0, now, 4096);

    char old_name[44], new_name[44];
    snprintf(old_name, sizeof(old_name), "%.40s.kv", old_sha);
    snprintf(new_name, sizeof(new_name), "%.40s.kv", new_sha);
    char *old_path = path_join(dir, old_name);
    char *new_path = path_join(dir, new_name);

    kv_disk_cache kc = {0};
    kc.enabled = true;
    kc.dir = xstrdup(dir);
    kc.opt = kv_cache_default_options();
    kc.budget_bytes = (KV_CACHE_FIXED_HEADER + 4u + 1024u) + 16u;
    kv_cache_evict(&kc, NULL, new_sha);

    TEST_ASSERT(access(old_path, F_OK) == 0);
    TEST_ASSERT(access(new_path, F_OK) != 0);

    kv_cache_close(&kc);
    unlink(old_path);
    unlink(new_path);
    free(old_path);
```

<｜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_server.c

```c
close(&kc);
    unlink(old_path);
    unlink(new_path);
    free(old_path);
    free(new_path);
    rmdir(dir);
}

static void test_kv_cache_eviction_protects_current_store(void) {
    char tmpl[] = "/tmp/ds4-kv-current-store-evict-test.XXXXXX";
    char *dir = mkdtemp(tmpl);
    TEST_ASSERT(dir != NULL);
    if (!dir) return;

    const char *old_sha = "1111111111111111111111111111111111111111";
    const char *new_sha = "2222222222222222222222222222222222222222";
    uint64_t now = (uint64_t)time(NULL);
    test_kv_stub_file(dir, old_sha, KV_REASON_COLD, 4096, 0, now, 2048);
    test_kv_stub_file(dir, new_sha, KV_REASON_CONTINUED, 2048, 0, now, 4096);

    char old_name[44], new_name[44];
    snprintf(old_name, sizeof(old_name), "%.40s.kv", old_sha);
    snprintf(new_name, sizeof(new_name), "%.40s.kv", new_sha);
    char *old_path = path_join(dir, old_name);
    char *new_path = path_join(dir, new_name);

    kv_disk_cache kc = {0};
    kc.enabled = true;
    kc.dir = xstrdup(dir);
    kc.opt = kv_cache_default_options();
    kc.budget_bytes = (KV_CACHE_FIXED_HEADER + 4u + 4096u) + 16u;
    kv_cache_evict(&kc, NULL, new_sha);

    TEST_ASSERT(access(old_path, F_OK) != 0);
    TEST_ASSERT(access(new_path, F_OK) == 0);

    kv_cache_close(&kc);
    unlink(old_path);
    unlink(new_path);
    free(old_path);
    free(new_path);
    rmdir(dir);
}

static void test_kv_cache_eviction_does_not_protect_oversize_current_store(void) {
    char tmpl[] = "/tmp/ds4-kv-oversize-store-evict-test.XXXXXX";
    char *dir = mkdtemp(tmpl);
    TEST_ASSERT(dir != NULL);
    if (!dir) return;

    const char *old_sha = "1111111111111111111111111111111111111111";
    const char *new_sha = "2222222222222222222222222222222222222222";
    uint64_t now = (uint64_t)time(NULL);
    test_kv_stub_file(dir, old_sha, KV_REASON_COLD, 4096, 0, now, 1024);
    test_kv_stub_file(dir, new_sha, KV_REASON_CONTINUED, 4096, 0, now, 4096);

    char old_name[44], new_name[44];
    snprintf(old_name, sizeof(old_name), "%.40s.kv", old_sha);
    snprintf(new_name, sizeof(new_name), "%.40s.kv", new_sha);
    char *old_path = path_join(dir, old_name);
    char *new_path = path_join(dir, new_name);

    kv_disk_cache kc = {0};
    kc.enabled = true;
    kc.dir = xstrdup(dir);
    kc.opt = kv_cache_default_options();
    kc.budget_bytes = (KV_CACHE_FIXED_HEADER + 4u + 1024u) + 16u;
    kv_cache_evict(&kc, NULL, new_sha);

    TEST_ASSERT(access(old_path, F_OK) == 0);
    TEST_ASSERT(access(new_path, F_OK) != 0);

    kv_cache_close(&kc);
    unlink(old_path);
    unlink(new_path);
    free(old_path);
```<｜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_server.c

```c
close(&kc);
    unlink(old_path);
    unlink(new_path);
    free(old_path);
    free(new_path);
    rmdir(dir);
}

static void test_kv_cache_eviction_protects_current_store(void) {
    char tmpl[] = "/tmp/ds4-kv-current-store-evict-test.XXXXXX";
    char *dir = mkdtemp(tmpl);
    TEST_ASSERT(dir != NULL);
    if (!dir) return;

    const char *old_sha = "1111111111111111111111111111111111111111";
    const char *new_sha = "2222222222222222222222222222222222222222";
    uint64_t now = (uint64_t)time(NULL);
    test_kv_stub_file(dir, old_sha, KV_REASON_COLD, 4096, 0, now, 2048);
    test_kv_stub_file(dir, new_sha, KV_REASON_CONTINUED, 2048, 0, now, 4096);

    char old_name[44], new_name[44];
    snprintf(old_name, sizeof(old_name), "%.40s.kv", old_sha);
    snprintf(new_name, sizeof(new_name), "%.40s.kv", new_sha);
    char *old_path = path_join(dir, old_name);
    char *new_path = path_join(dir, new_name);

    kv_disk_cache kc = {0};
    kc.enabled = true;
    kc.dir = xstrdup(dir);
    kc.opt = kv_cache_default_options();
    kc.budget_bytes = (KV_CACHE_FIXED_HEADER + 4u + 4096u) + 16u;
    kv_cache_evict(&kc, NULL, new_sha);

    TEST_ASSERT(access(old_path, F_OK) != 0);
    TEST_ASSERT(access(new_path, F_OK) == 0);

    kv_cache_close(&kc);
    unlink(old_path);
    unlink(new_path);
    free(old_path);
    free(new_path);
    rmdir(dir);
}

static void test_kv_cache_eviction_does_not_protect_oversize_current_store(void) {
    char tmpl[] = "/tmp/ds4-kv-oversize-store-evict-test.XXXXXX";
    char *dir = mkdtemp(tmpl);
    TEST_ASSERT(dir != NULL);
    if (!dir) return;

    const char *old_sha = "1111111111111111111111111111111111111111";
    const char *new_sha = "2222222222222222222222222222222222222222";
    uint64_t now = (uint64_t)time(NULL);
    test_kv_stub_file(dir, old_sha, KV_REASON_COLD, 4096, 0, now, 1024);
    test_kv_stub_file(dir, new_sha, KV_REASON_CONTINUED, 4096, 0, now, 4096);

    char old_name[44], new_name[44];
    snprintf(old_name, sizeof(old_name), "%.40s.kv", old_sha);
    snprintf(new_name, sizeof(new_name), "%.40s.kv", new_sha);
    char *old_path = path_join(dir, old_name);
    char *new_path = path_join(dir, new_name);

    kv_disk_cache kc = {0};
    kc.enabled = true;
    kc.dir = xstrdup(dir);
    kc.opt = kv_cache_default_options();
    kc.budget_bytes = (KV_CACHE_FIXED_HEADER + 4u + 1024u) + 16u;
    kv_cache_evict(&kc, NULL, new_sha);

    TEST_ASSERT(access(old_path, F_OK) == 0);
    TEST_ASSERT(access(new_path, F_OK) != 0);

    kv_cache_close(&kc);
    unlink(old_path);
    unlink(new_path);
    free(old_path);
```

<｜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_server.c

```c
close(&kc);
    unlink(old_path);
    unlink(new_path);
    free(old_path);
    free(new_path);
    rmdir(dir);
}

static void test_kv_cache_eviction_protects_current_store(void) {
    char tmpl[] = "/tmp/ds4-kv-current-store-evict-test.XXXXXX";
    char *dir = mkdtemp(tmpl);
    TEST_ASSERT(dir != NULL);
    if (!dir) return;

    const char *old_sha = "1111111111111111111111111111111111111111";
    const char *new_sha = "2222222222222222222222222222222222222222";
    uint64_t now = (uint64_t)time(NULL);
    test_kv_stub_file(dir, old_sha, KV_REASON_COLD, 4096, 0, now, 2048);
    test_kv_stub_file(dir, new_sha, KV_REASON_CONTINUED, 2048, 0, now, 4096);

    char old_name[44], new_name[44];
    snprintf(old_name, sizeof(old_name), "%.40s.kv", old_sha);
    snprintf(new_name, sizeof(new_name), "%.40s.kv", new_sha);
    char *old_path = path_join(dir, old_name);
    char *new_path = path_join(dir, new_name);

    kv_disk_cache kc = {0};
    kc.enabled = true;
    kc.dir = xstrdup(dir);
    kc.opt = kv_cache_default_options();
    kc.budget_bytes = (KV_CACHE_FIXED_HEADER + 4u + 4096u) + 16u;
    kv_cache_evict(&kc, NULL, new_sha);

    TEST_ASSERT(access(old_path, F_OK) != 0);
    TEST_ASSERT(access(new_path, F_OK) == 0);

    kv_cache_close(&kc);
    unlink(old_path);
    unlink(new_path);
    free(old_path);
    free(new_path);
    rmdir(dir);
}

static void test_kv_cache_eviction_does_not_protect_oversize_current_store(void) {
    char tmpl[] = "/tmp/ds4-kv-oversize-store-evict-test.XXXXXX";
    char *dir = mkdtemp(tmpl);
    TEST_ASSERT(dir != NULL);
    if (!dir) return;

    const char *old_sha = "1111111111111111111111111111111111111111";
    const char *new_sha = "2222222222222222222222222222222222222222";
    uint64_t now = (uint64_t)time(NULL);
    test_kv_stub_file(dir, old_sha, KV_REASON_COLD, 4096, 0, now, 1024);
    test_kv_stub_file(dir, new_sha, KV_REASON_CONTINUED, 4096, 0, now, 4096);

    char old_name[44], new_name[44];
    snprintf(old_name, sizeof(old_name), "%.40s.kv", old_sha);
    snprintf(new_name, sizeof(new_name), "%.40s.kv", new_sha);
    char *old_path = path_join(dir, old_name);
    char *new_path = path_join(dir, new_name);

    kv_disk_cache kc = {0};
    kc.enabled = true;
    kc.dir = xstrdup(dir);
    kc.opt = kv_cache_default_options();
    kc.budget_bytes = (KV_CACHE_FIXED_HEADER + 4u + 1024u) + 16u;
    kv_cache_evict(&kc, NULL, new_sha);

    TEST_ASSERT(access(old_path, F_OK) == 0);
    TEST_ASSERT(access(new_path, F_OK) != 0);

    kv_cache_close(&kc);
    unlink(old_path);
    unlink(new_path);
    free(old_path);
```<｜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_server.c

```c
TEST_ASSERT(access(old_path, F_OK) == 0);
    TEST_ASSERT(access(new_path, F_OK) != 0);

    kv_cache_close(&kc);
    unlink(old_path);
    unlink(new_path);
    free(old_path);
    free(new_path);
    rmdir(dir);
}

static void test_kv_cache_eviction_score_decays_stale_hits(void) {
    /* stale: lower tokens-per-byte (e.g. tool-heavy prompt) but boosted by
     * 10 hits well in the past.  fresh: higher tokens-per-byte and zero hits,
     * just stored.  The stale hit bonus decays by inactivity, so fresh wins on
     * its better baseline even though stale once had more successful hits. */
    const uint64_t now = 1000u + 14u * KV_CACHE_HIT_HALF_LIFE_SECONDS;
    kv_entry stale = {.tokens = 1024, .hits = 10, .file_size = 4096, .last_used = 1000};
    kv_entry fresh = {.tokens = 2048, .hits = 0,  .file_size = 4096, .last_used = now};

    double s_on = kv_entry_eviction_score(&stale, NULL, NULL, now);
    double f_on = kv_entry_eviction_score(&fresh, NULL, NULL, now);
    TEST_ASSERT(s_on < f_on);

    /* A fresh entry's score never decays below its (0+1) * tokens/size floor,
     * regardless of how old another entry's hit history is. */
    TEST_ASSERT(f_on == 1.0 * (double)fresh.tokens / (double)fresh.file_size);
}

static void test_kv_cache_eviction_decayed_hits_tie_break_by_age(void) {
    char tmpl[] = "/tmp/ds4-kv-stale-hit-evict-test.XXXXXX";
    char *dir = mkdtemp(tmpl);
    TEST_ASSERT(dir != NULL);
    if (!dir) return;

    const char *old_sha = "1111111111111111111111111111111111111111";
    const char *new_sha = "2222222222222222222222222222222222222222";
    uint64_t now = (uint64_t)time(NULL);
    uint64_t stale = now > KV_CACHE_HIT_HALF_LIFE_SECONDS * 14ull
        ? now - KV_CACHE_HIT_HALF_LIFE_SECONDS * 14ull
        : 1;
    test_kv_stub_file(dir, old_sha, KV_REASON_COLD, 2048, 15, stale, 2048);
    test_kv_stub_file(dir, new_sha, KV_REASON_COLD, 2048, 0, now, 2048);

    char old_name[44], new_name[44];
    snprintf(old_name, sizeof(old_name), "%.40s.kv", old_sha);
    snprintf(new_name, sizeof(new_name), "%.40s.kv", new_sha);
    char *old_path = path_join(dir, old_name);
    char *new_path = path_join(dir, new_name);

    kv_disk_cache kc = {0};
    kc.enabled = true;
    kc.dir = xstrdup(dir);
    kc.opt = kv_cache_default_options();
    kc.budget_bytes = (KV_CACHE_FIXED_HEADER + 4u + 2048u) + 16u;
    kv_cache_evict(&kc, NULL, NULL);

    TEST_ASSERT(access(old_path, F_OK) != 0);
    TEST_ASSERT(access(new_path, F_OK) == 0);

    kv_cache_close(&kc);
    unlink(old_path);
    unlink(new_path);
    free(old_path);
```

<｜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_server.c

```c
TEST_ASSERT(access(old_path, F_OK) == 0);
    TEST_ASSERT(access(new_path, F_OK) != 0);

    kv_cache_close(&kc);
    unlink(old_path);
    unlink(new_path);
    free(old_path);
    free(new_path);
    rmdir(dir);
}

static void test_kv_cache_eviction_score_decays_stale_hits(void) {
    /* stale: lower tokens-per-byte (e.g. tool-heavy prompt) but boosted by
     * 10 hits well in the past.  fresh: higher tokens-per-byte and zero hits,
     * just stored.  The stale hit bonus decays by inactivity, so fresh wins on
     * its better baseline even though stale once had more successful hits. */
    const uint64_t now = 1000u + 14u * KV_CACHE_HIT_HALF_LIFE_SECONDS;
    kv_entry stale = {.tokens = 1024, .hits = 10, .file_size = 4096, .last_used = 1000};
    kv_entry fresh = {.tokens = 2048, .hits = 0,  .file_size = 4096, .last_used = now};

    double s_on = kv_entry_eviction_score(&stale, NULL, NULL, now);
    double f_on = kv_entry_eviction_score(&fresh, NULL, NULL, now);
    TEST_ASSERT(s_on < f_on);

    /* A fresh entry's score never decays below its (0+1) * tokens/size floor,
     * regardless of how old another entry's hit history is. */
    TEST_ASSERT(f_on == 1.0 * (double)fresh.tokens / (double)fresh.file_size);
}

static void test_kv_cache_eviction_decayed_hits_tie_break_by_age(void) {
    char tmpl[] = "/tmp/ds4-kv-stale-hit-evict-test.XXXXXX";
    char *dir = mkdtemp(tmpl);
    TEST_ASSERT(dir != NULL);
    if (!dir) return;

    const char *old_sha = "1111111111111111111111111111111111111111";
    const char *new_sha = "2222222222222222222222222222222222222222";
    uint64_t now = (uint64_t)time(NULL);
    uint64_t stale = now > KV_CACHE_HIT_HALF_LIFE_SECONDS * 14ull
        ? now - KV_CACHE_HIT_HALF_LIFE_SECONDS * 14ull
        : 1;
    test_kv_stub_file(dir, old_sha, KV_REASON_COLD, 2048, 15, stale, 2048);
    test_kv_stub_file(dir, new_sha, KV_REASON_COLD, 2048, 0, now, 2048);

    char old_name[44], new_name[44];
    snprintf(old_name, sizeof(old_name), "%.40s.kv", old_sha);
    snprintf(new_name, sizeof(new_name), "%.40s.kv", new_sha);
    char *old_path = path_join(dir, old_name);
    char *new_path = path_join(dir, new_name);

    kv_disk_cache kc = {0};
    kc.enabled = true;
    kc.dir = xstrdup(dir);
    kc.opt = kv_cache_default_options();
    kc.budget_bytes = (KV_CACHE_FIXED_HEADER + 4u + 2048u) + 16u;
    kv_cache_evict(&kc, NULL, NULL);

    TEST_ASSERT(access(old_path, F_OK) != 0);
    TEST_ASSERT(access(new_path, F_OK) == 0);

    kv_cache_close(&kc);
    unlink(old_path);
    unlink(new_path);
    free(old_path);
```<｜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_server.c

```c
TEST_ASSERT(access(old_path, F_OK) == 0);
    TEST_ASSERT(access(new_path, F_OK) != 0);

    kv_cache_close(&kc);
    unlink(old_path);
    unlink(new_path);
    free(old_path);
    free(new_path);
    rmdir(dir);
}

static void test_kv_cache_eviction_score_decays_stale_hits(void) {
    /* stale: lower tokens-per-byte (e.g. tool-heavy prompt) but boosted by
     * 10 hits well in the past.  fresh: higher tokens-per-byte and zero hits,
     * just stored.  The stale hit bonus decays by inactivity, so fresh wins on
     * its better baseline even though stale once had more successful hits. */
    const uint64_t now = 1000u + 14u * KV_CACHE_HIT_HALF_LIFE_SECONDS;
    kv_entry stale = {.tokens = 1024, .hits = 10, .file_size = 4096, .last_used = 1000};
    kv_entry fresh = {.tokens = 2048, .hits = 0,  .file_size = 4096, .last_used = now};

    double s_on = kv_entry_eviction_score(&stale, NULL, NULL, now);
    double f_on = kv_entry_eviction_score(&fresh, NULL, NULL, now);
    TEST_ASSERT(s_on < f_on);

    /* A fresh entry's score never decays below its (0+1) * tokens/size floor,
     * regardless of how old another entry's hit history is. */
    TEST_ASSERT(f_on == 1.0 * (double)fresh.tokens / (double)fresh.file_size);
}

static void test_kv_cache_eviction_decayed_hits_tie_break_by_age(void) {
    char tmpl[] = "/tmp/ds4-kv-stale-hit-evict-test.XXXXXX";
    char *dir = mkdtemp(tmpl);
    TEST_ASSERT(dir != NULL);
    if (!dir) return;

    const char *old_sha = "1111111111111111111111111111111111111111";
    const char *new_sha = "2222222222222222222222222222222222222222";
    uint64_t now = (uint64_t)time(NULL);
    uint64_t stale = now > KV_CACHE_HIT_HALF_LIFE_SECONDS * 14ull
        ? now - KV_CACHE_HIT_HALF_LIFE_SECONDS * 14ull
        : 1;
    test_kv_stub_file(dir, old_sha, KV_REASON_COLD, 2048, 15, stale, 2048);
    test_kv_stub_file(dir, new_sha, KV_REASON_COLD, 2048, 0, now, 2048);

    char old_name[44], new_name[44];
    snprintf(old_name, sizeof(old_name), "%.40s.kv", old_sha);
    snprintf(new_name, sizeof(new_name), "%.40s.kv", new_sha);
    char *old_path = path_join(dir, old_name);
    char *new_path = path_join(dir, new_name);

    kv_disk_cache kc = {0};
    kc.enabled = true;
    kc.dir = xstrdup(dir);
    kc.opt = kv_cache_default_options();
    kc.budget_bytes = (KV_CACHE_FIXED_HEADER + 4u + 2048u) + 16u;
    kv_cache_evict(&kc, NULL, NULL);

    TEST_ASSERT(access(old_path, F_OK) != 0);
    TEST_ASSERT(access(new_path, F_OK) == 0);

    kv_cache_close(&kc);
    unlink(old_path);
    unlink(new_path);
    free(old_path);
```

<｜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_server.c

```c
TEST_ASSERT(access(old_path, F_OK) == 0);
    TEST_ASSERT(access(new_path, F_OK) != 0);

    kv_cache_close(&kc);
    unlink(old_path);
    unlink(new_path);
    free(old_path);
    free(new_path);
    rmdir(dir);
}

static void test_kv_cache_eviction_score_decays_stale_hits(void) {
    /* stale: lower tokens-per-byte (e.g. tool-heavy prompt) but boosted by
     * 10 hits well in the past.  fresh: higher tokens-per-byte and zero hits,
     * just stored.  The stale hit bonus decays by inactivity, so fresh wins on
     * its better baseline even though stale once had more successful hits. */
    const uint64_t now = 1000u + 14u * KV_CACHE_HIT_HALF_LIFE_SECONDS;
    kv_entry stale = {.tokens = 1024, .hits = 10, .file_size = 4096, .last_used = 1000};
    kv_entry fresh = {.tokens = 2048, .hits = 0,  .file_size = 4096, .last_used = now};

    double s_on = kv_entry_eviction_score(&stale, NULL, NULL, now);
    double f_on = kv_entry_eviction_score(&fresh, NULL, NULL, now);
    TEST_ASSERT(s_on < f_on);

    /* A fresh entry's score never decays below its (0+1) * tokens/size floor,
     * regardless of how old another entry's hit history is. */
    TEST_ASSERT(f_on == 1.0 * (double)fresh.tokens / (double)fresh.file_size);
}

static void test_kv_cache_eviction_decayed_hits_tie_break_by_age(void) {
    char tmpl[] = "/tmp/ds4-kv-stale-hit-evict-test.XXXXXX";
    char *dir = mkdtemp(tmpl);
    TEST_ASSERT(dir != NULL);
    if (!dir) return;

    const char *old_sha = "1111111111111111111111111111111111111111";
    const char *new_sha = "2222222222222222222222222222222222222222";
    uint64_t now = (uint64_t)time(NULL);
    uint64_t stale = now > KV_CACHE_HIT_HALF_LIFE_SECONDS * 14ull
        ? now - KV_CACHE_HIT_HALF_LIFE_SECONDS * 14ull
        : 1;
    test_kv_stub_file(dir, old_sha, KV_REASON_COLD, 2048, 15, stale, 2048);
    test_kv_stub_file(dir, new_sha, KV_REASON_COLD, 2048, 0, now, 2048);

    char old_name[44], new_name[44];
    snprintf(old_name, sizeof(old_name), "%.40s.kv", old_sha);
    snprintf(new_name, sizeof(new_name), "%.40s.kv", new_sha);
    char *old_path = path_join(dir, old_name);
    char *new_path = path_join(dir, new_name);

    kv_disk_cache kc = {0};
    kc.enabled = true;
    kc.dir = xstrdup(dir);
    kc.opt = kv_cache_default_options();
    kc.budget_bytes = (KV_CACHE_FIXED_HEADER + 4u + 2048u) + 16u;
    kv_cache_evict(&kc, NULL, NULL);

    TEST_ASSERT(access(old_path, F_OK) != 0);
    TEST_ASSERT(access(new_path, F_OK) == 0);

    kv_cache_close(&kc);
    unlink(old_path);
    unlink(new_path);
    free(old_path);
```<｜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_server.c

```c
TEST_ASSERT(access(old_path, F_OK) != 0);
    TEST_ASSERT(access(new_path, F_OK) == 0);

    kv_cache_close(&kc);
    unlink(old_path);
    unlink(new_path);
    free(old_path);
    free(new_path);
    rmdir(dir);
}

static void test_kv_cache_eviction_keeps_aligned_continued_frontiers(void) {
    char tmpl[] = "/tmp/ds4-kv-live-prefix-test.XXXXXX";
    char *dir = mkdtemp(tmpl);
    TEST_ASSERT(dir != NULL);
    if (!dir) return;

    const char *cold_sha = "1111111111111111111111111111111111111111";
    const char *continued_sha = "2222222222222222222222222222222222222222";
    uint64_t now = (uint64_t)time(NULL);
    test_kv_stub_file(dir, cold_sha, KV_REASON_COLD, 512, 0, now, 2048);
    test_kv_stub_file(dir, continued_sha, KV_REASON_CONTINUED, 2048, 0, now, 2048);

    char cold_name[44], continued_name[44];
    snprintf(cold_name, sizeof(cold_name), "%.40s.kv", cold_sha);
    snprintf(continued_name, sizeof(continued_name), "%.40s.kv", continued_sha);
    char *cold_path = path_join(dir, cold_name);
    char *continued_path = path_join(dir, continued_name);

    kv_disk_cache kc = {0};
    kc.enabled = true;
    kc.dir = xstrdup(dir);
    kc.opt = kv_cache_default_options();
    kc.budget_bytes = (KV_CACHE_FIXED_HEADER + 4u + 2048u) + 16u;
    kv_cache_evict(&kc, NULL, NULL);

    TEST_ASSERT(access(cold_path, F_OK) != 0);
    TEST_ASSERT(access(continued_path, F_OK) == 0);

    kv_cache_close(&kc);
    unlink(cold_path);
    unlink(continued_path);
    free(cold_path);
    free(continued_path);
    rmdir(dir);
}

static void test_thinking_checkpoint_canonical_matches_future_prompt(void) {
    /* Simulate: user sends a single message, thinking mode on, no tools.
     * Model generates reasoning + content.  The next request will drop the
     * reasoning from this turn.  Verify that:
     *   prompt_text[:-len("<think>")] + "</think>" + content + "<|eos|>"
     * equals what render_chat_prompt_text produces for the history. */

    chat_msgs prefix_msgs = {0};
    chat_msg user1 = {0};
    user1.role = xstrdup("user");
    user1.content = xstrdup("What is 2+2?");
    chat_msgs_push(&prefix_msgs, user1);

    /* This is what prompt_text looks like for the first generation */
    char *prompt_text = render_chat_prompt_text(&prefix_msgs, NULL, NULL, DS4_THINK_HIGH);
    /* prompt_text should end with <think> */
    size_t pt_len = strlen(prompt_text);
    TEST_ASSERT(pt_len >= 7);
    TEST_ASSERT(!memcmp(prompt_text + pt_len - 7, "<think>", 7));

    /* The model generates: reasoning + </think> + content */
```

<｜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_server.c

```c
TEST_ASSERT(access(old_path, F_OK) != 0);
    TEST_ASSERT(access(new_path, F_OK) == 0);

    kv_cache_close(&kc);
    unlink(old_path);
    unlink(new_path);
    free(old_path);
    free(new_path);
    rmdir(dir);
}

static void test_kv_cache_eviction_keeps_aligned_continued_frontiers(void) {
    char tmpl[] = "/tmp/ds4-kv-live-prefix-test.XXXXXX";
    char *dir = mkdtemp(tmpl);
    TEST_ASSERT(dir != NULL);
    if (!dir) return;

    const char *cold_sha = "1111111111111111111111111111111111111111";
    const char *continued_sha = "2222222222222222222222222222222222222222";
    uint64_t now = (uint64_t)time(NULL);
    test_kv_stub_file(dir, cold_sha, KV_REASON_COLD, 512, 0, now, 2048);
    test_kv_stub_file(dir, continued_sha, KV_REASON_CONTINUED, 2048, 0, now, 2048);

    char cold_name[44], continued_name[44];
    snprintf(cold_name, sizeof(cold_name), "%.40s.kv", cold_sha);
    snprintf(continued_name, sizeof(continued_name), "%.40s.kv", continued_sha);
    char *cold_path = path_join(dir, cold_name);
    char *continued_path = path_join(dir, continued_name);

    kv_disk_cache kc = {0};
    kc.enabled = true;
    kc.dir = xstrdup(dir);
    kc.opt = kv_cache_default_options();
    kc.budget_bytes = (KV_CACHE_FIXED_HEADER + 4u + 2048u) + 16u;
    kv_cache_evict(&kc, NULL, NULL);

    TEST_ASSERT(access(cold_path, F_OK) != 0);
    TEST_ASSERT(access(continued_path, F_OK) == 0);

    kv_cache_close(&kc);
    unlink(cold_path);
    unlink(continued_path);
    free(cold_path);
    free(continued_path);
    rmdir(dir);
}

static void test_thinking_checkpoint_canonical_matches_future_prompt(void) {
    /* Simulate: user sends a single message, thinking mode on, no tools.
     * Model generates reasoning + content.  The next request will drop the
     * reasoning from this turn.  Verify that:
     *   prompt_text[:-len("<think>")] + "</think>" + content + "<|eos|>"
     * equals what render_chat_prompt_text produces for the history. */

    chat_msgs prefix_msgs = {0};
    chat_msg user1 = {0};
    user1.role = xstrdup("user");
    user1.content = xstrdup("What is 2+2?");
    chat_msgs_push(&prefix_msgs, user1);

    /* This is what prompt_text looks like for the first generation */
    char *prompt_text = render_chat_prompt_text(&prefix_msgs, NULL, NULL, DS4_THINK_HIGH);
    /* prompt_text should end with <think> */
    size_t pt_len = strlen(prompt_text);
    TEST_ASSERT(pt_len >= 7);
    TEST_ASSERT(!memcmp(prompt_text + pt_len - 7, "<think>", 7));

    /* The model generates: reasoning + </think> + content */
```<｜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_server.c

```c
TEST_ASSERT(access(old_path, F_OK) != 0);
    TEST_ASSERT(access(new_path, F_OK) == 0);

    kv_cache_close(&kc);
    unlink(old_path);
    unlink(new_path);
    free(old_path);
    free(new_path);
    rmdir(dir);
}

static void test_kv_cache_eviction_keeps_aligned_continued_frontiers(void) {
    char tmpl[] = "/tmp/ds4-kv-live-prefix-test.XXXXXX";
    char *dir = mkdtemp(tmpl);
    TEST_ASSERT(dir != NULL);
    if (!dir) return;

    const char *cold_sha = "1111111111111111111111111111111111111111";
    const char *continued_sha = "2222222222222222222222222222222222222222";
    uint64_t now = (uint64_t)time(NULL);
    test_kv_stub_file(dir, cold_sha, KV_REASON_COLD, 512, 0, now, 2048);
    test_kv_stub_file(dir, continued_sha, KV_REASON_CONTINUED, 2048, 0, now, 2048);

    char cold_name[44], continued_name[44];
    snprintf(cold_name, sizeof(cold_name), "%.40s.kv", cold_sha);
    snprintf(continued_name, sizeof(continued_name), "%.40s.kv", continued_sha);
    char *cold_path = path_join(dir, cold_name);
    char *continued_path = path_join(dir, continued_name);

    kv_disk_cache kc = {0};
    kc.enabled = true;
    kc.dir = xstrdup(dir);
    kc.opt = kv_cache_default_options();
    kc.budget_bytes = (KV_CACHE_FIXED_HEADER + 4u + 2048u) + 16u;
    kv_cache_evict(&kc, NULL, NULL);

    TEST_ASSERT(access(cold_path, F_OK) != 0);
    TEST_ASSERT(access(continued_path, F_OK) == 0);

    kv_cache_close(&kc);
    unlink(cold_path);
    unlink(continued_path);
    free(cold_path);
    free(continued_path);
    rmdir(dir);
}

static void test_thinking_checkpoint_canonical_matches_future_prompt(void) {
    /* Simulate: user sends a single message, thinking mode on, no tools.
     * Model generates reasoning + content.  The next request will drop the
     * reasoning from this turn.  Verify that:
     *   prompt_text[:-len("<think>")] + "</think>" + content + "<|eos|>"
     * equals what render_chat_prompt_text produces for the history. */

    chat_msgs prefix_msgs = {0};
    chat_msg user1 = {0};
    user1.role = xstrdup("user");
    user1.content = xstrdup("What is 2+2?");
    chat_msgs_push(&prefix_msgs, user1);

    /* This is what prompt_text looks like for the first generation */
    char *prompt_text = render_chat_prompt_text(&prefix_msgs, NULL, NULL, DS4_THINK_HIGH);
    /* prompt_text should end with <think> */
    size_t pt_len = strlen(prompt_text);
    TEST_ASSERT(pt_len >= 7);
    TEST_ASSERT(!memcmp(prompt_text + pt_len - 7, "<think>", 7));

    /* The model generates: reasoning + </think> + content */
```

<｜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_server.c

```c
TEST_ASSERT(access(old_path, F_OK) != 0);
    TEST_ASSERT(access(new_path, F_OK) == 0);

    kv_cache_close(&kc);
    unlink(old_path);
    unlink(new_path);
    free(old_path);
    free(new_path);
    rmdir(dir);
}

static void test_kv_cache_eviction_keeps_aligned_continued_frontiers(void) {
    char tmpl[] = "/tmp/ds4-kv-live-prefix-test.XXXXXX";
    char *dir = mkdtemp(tmpl);
    TEST_ASSERT(dir != NULL);
    if (!dir) return;

    const char *cold_sha = "1111111111111111111111111111111111111111";
    const char *continued_sha = "2222222222222222222222222222222222222222";
    uint64_t now = (uint64_t)time(NULL);
    test_kv_stub_file(dir, cold_sha, KV_REASON_COLD, 512, 0, now, 2048);
    test_kv_stub_file(dir, continued_sha, KV_REASON_CONTINUED, 2048, 0, now, 2048);

    char cold_name[44], continued_name[44];
    snprintf(cold_name, sizeof(cold_name), "%.40s.kv", cold_sha);
    snprintf(continued_name, sizeof(continued_name), "%.40s.kv", continued_sha);
    char *cold_path = path_join(dir, cold_name);
    char *continued_path = path_join(dir, continued_name);

    kv_disk_cache kc = {0};
    kc.enabled = true;
    kc.dir = xstrdup(dir);
    kc.opt = kv_cache_default_options();
    kc.budget_bytes = (KV_CACHE_FIXED_HEADER + 4u + 2048u) + 16u;
    kv_cache_evict(&kc, NULL, NULL);

    TEST_ASSERT(access(cold_path, F_OK) != 0);
    TEST_ASSERT(access(continued_path, F_OK) == 0);

    kv_cache_close(&kc);
    unlink(cold_path);
    unlink(continued_path);
    free(cold_path);
    free(continued_path);
    rmdir(dir);
}

static void test_thinking_checkpoint_canonical_matches_future_prompt(void) {
    /* Simulate: user sends a single message, thinking mode on, no tools.
     * Model generates reasoning + content.  The next request will drop the
     * reasoning from this turn.  Verify that:
     *   prompt_text[:-len("<think>")] + "</think>" + content + "<|eos|>"
     * equals what render_chat_prompt_text produces for the history. */

    chat_msgs prefix_msgs = {0};
    chat_msg user1 = {0};
    user1.role = xstrdup("user");
    user1.content = xstrdup("What is 2+2?");
    chat_msgs_push(&prefix_msgs, user1);

    /* This is what prompt_text looks like for the first generation */
    char *prompt_text = render_chat_prompt_text(&prefix_msgs, NULL, NULL, DS4_THINK_HIGH);
    /* prompt_text should end with <think> */
    size_t pt_len = strlen(prompt_text);
    TEST_ASSERT(pt_len >= 7);
    TEST_ASSERT(!memcmp(prompt_text + pt_len - 7, "<think>", 7));

    /* The model generates: reasoning + </think> + content */
```<｜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_server.c

```c
strlen(prompt_text);
    TEST_ASSERT(pt_len >= 7);
    TEST_ASSERT(!memcmp(prompt_text + pt_len - 7, "<think>", 7));

    /* The model generates: reasoning + </think> + content */
    const char *reasoning = "Let me think... 2+2 = 4";
    const char *content = "The answer is 4.";

    /* Build the canonical checkpoint text (what we'd produce after canonicalization) */
    buf canonical = {0};
    buf_append(&canonical, prompt_text, pt_len - 7);  /* strip <think> */
    buf_puts(&canonical, "</think>");
    buf_puts(&canonical, content);
    buf_puts(&canonical, "<" "\xef\xbd\x9c" "end" "\xe2\x96\x81" "of" "\xe2\x96\x81" "sentence" "\xef\xbd\x9c" ">");

    request r;
    request_init(&r, REQ_CHAT, 128);
    r.think_mode = DS4_THINK_HIGH;
    r.prompt_text = xstrdup(prompt_text);
    char *visible = build_toolless_thinking_visible_text(&r, content);
    TEST_ASSERT(visible != NULL);
    TEST_ASSERT(!strcmp(visible, canonical.ptr));
    free(visible);
    request_free(&r);

    /* Now build what the NEXT request would render: history includes this
     * assistant message, plus a new user message.  Extract just the prefix
     * up to and including the eos of the assistant turn. */
    chat_msgs history_msgs = {0};
    chat_msg h_user1 = {0};
    h_user1.role = xstrdup("user");
    h_user1.content = xstrdup("What is 2+2?");
    chat_msgs_push(&history_msgs, h_user1);
    chat_msg h_asst = {0};
    h_asst.role = xstrdup("assistant");
    h_asst.reasoning = xstrdup(reasoning);
    h_asst.content = xstrdup(content);
    chat_msgs_push(&history_msgs, h_asst);
    chat_msg h_user2 = {0};
    h_user2.role = xstrdup("user");
    h_user2.content = xstrdup("Thanks!");
    chat_msgs_push(&history_msgs, h_user2);

    char *future_prompt = render_chat_prompt_text(&history_msgs, NULL, NULL, DS4_THINK_HIGH);

    /* The future prompt should START with our canonical text */
    size_t clen = canonical.len;
    TEST_ASSERT(strlen(future_prompt) > clen);
    TEST_ASSERT(!memcmp(future_prompt, canonical.ptr, clen));

    /* And what comes after is the new user turn + assistant prefix */
    const char *rest = future_prompt + clen;
    TEST_ASSERT(strstr(rest, "Thanks!") != NULL);
    TEST_ASSERT(strstr(rest, "<think>") != NULL);  /* new turn starts thinking */

    /* Verify reasoning is NOT in the future prompt for this turn */
    const char *asst_turn = strstr(future_prompt, "<" "\xef\xbd\x9c" "Assistant" "\xef\xbd\x9c" ">");
    TEST_ASSERT(asst_turn != NULL);
    TEST_ASSERT(strstr(future_prompt, reasoning) == NULL);  /* reasoning dropped */
```

<｜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_server.c

```c
strlen(prompt_text);
    TEST_ASSERT(pt_len >= 7);
    TEST_ASSERT(!memcmp(prompt_text + pt_len - 7, "<think>", 7));

    /* The model generates: reasoning + </think> + content */
    const char *reasoning = "Let me think... 2+2 = 4";
    const char *content = "The answer is 4.";

    /* Build the canonical checkpoint text (what we'd produce after canonicalization) */
    buf canonical = {0};
    buf_append(&canonical, prompt_text, pt_len - 7);  /* strip <think> */
    buf_puts(&canonical, "</think>");
    buf_puts(&canonical, content);
    buf_puts(&canonical, "<" "\xef\xbd\x9c" "end" "\xe2\x96\x81" "of" "\xe2\x96\x81" "sentence" "\xef\xbd\x9c" ">");

    request r;
    request_init(&r, REQ_CHAT, 128);
    r.think_mode = DS4_THINK_HIGH;
    r.prompt_text = xstrdup(prompt_text);
    char *visible = build_toolless_thinking_visible_text(&r, content);
    TEST_ASSERT(visible != NULL);
    TEST_ASSERT(!strcmp(visible, canonical.ptr));
    free(visible);
    request_free(&r);

    /* Now build what the NEXT request would render: history includes this
     * assistant message, plus a new user message.  Extract just the prefix
     * up to and including the eos of the assistant turn. */
    chat_msgs history_msgs = {0};
    chat_msg h_user1 = {0};
    h_user1.role = xstrdup("user");
    h_user1.content = xstrdup("What is 2+2?");
    chat_msgs_push(&history_msgs, h_user1);
    chat_msg h_asst = {0};
    h_asst.role = xstrdup("assistant");
    h_asst.reasoning = xstrdup(reasoning);
    h_asst.content = xstrdup(content);
    chat_msgs_push(&history_msgs, h_asst);
    chat_msg h_user2 = {0};
    h_user2.role = xstrdup("user");
    h_user2.content = xstrdup("Thanks!");
    chat_msgs_push(&history_msgs, h_user2);

    char *future_prompt = render_chat_prompt_text(&history_msgs, NULL, NULL, DS4_THINK_HIGH);

    /* The future prompt should START with our canonical text */
    size_t clen = canonical.len;
    TEST_ASSERT(strlen(future_prompt) > clen);
    TEST_ASSERT(!memcmp(future_prompt, canonical.ptr, clen));

    /* And what comes after is the new user turn + assistant prefix */
    const char *rest = future_prompt + clen;
    TEST_ASSERT(strstr(rest, "Thanks!") != NULL);
    TEST_ASSERT(strstr(rest, "<think>") != NULL);  /* new turn starts thinking */

    /* Verify reasoning is NOT in the future prompt for this turn */
    const char *asst_turn = strstr(future_prompt, "<" "\xef\xbd\x9c" "Assistant" "\xef\xbd\x9c" ">");
    TEST_ASSERT(asst_turn != NULL);
    TEST_ASSERT(strstr(future_prompt, reasoning) == NULL);  /* reasoning dropped */
```<｜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_server.c

```c
strlen(prompt_text);
    TEST_ASSERT(pt_len >= 7);
    TEST_ASSERT(!memcmp(prompt_text + pt_len - 7, "<think>", 7));

    /* The model generates: reasoning + </think> + content */
    const char *reasoning = "Let me think... 2+2 = 4";
    const char *content = "The answer is 4.";

    /* Build the canonical checkpoint text (what we'd produce after canonicalization) */
    buf canonical = {0};
    buf_append(&canonical, prompt_text, pt_len - 7);  /* strip <think> */
    buf_puts(&canonical, "</think>");
    buf_puts(&canonical, content);
    buf_puts(&canonical, "<" "\xef\xbd\x9c" "end" "\xe2\x96\x81" "of" "\xe2\x96\x81" "sentence" "\xef\xbd\x9c" ">");

    request r;
    request_init(&r, REQ_CHAT, 128);
    r.think_mode = DS4_THINK_HIGH;
    r.prompt_text = xstrdup(prompt_text);
    char *visible = build_toolless_thinking_visible_text(&r, content);
    TEST_ASSERT(visible != NULL);
    TEST_ASSERT(!strcmp(visible, canonical.ptr));
    free(visible);
    request_free(&r);

    /* Now build what the NEXT request would render: history includes this
     * assistant message, plus a new user message.  Extract just the prefix
     * up to and including the eos of the assistant turn. */
    chat_msgs history_msgs = {0};
    chat_msg h_user1 = {0};
    h_user1.role = xstrdup("user");
    h_user1.content = xstrdup("What is 2+2?");
    chat_msgs_push(&history_msgs, h_user1);
    chat_msg h_asst = {0};
    h_asst.role = xstrdup("assistant");
    h_asst.reasoning = xstrdup(reasoning);
    h_asst.content = xstrdup(content);
    chat_msgs_push(&history_msgs, h_asst);
    chat_msg h_user2 = {0};
    h_user2.role = xstrdup("user");
    h_user2.content = xstrdup("Thanks!");
    chat_msgs_push(&history_msgs, h_user2);

    char *future_prompt = render_chat_prompt_text(&history_msgs, NULL, NULL, DS4_THINK_HIGH);

    /* The future prompt should START with our canonical text */
    size_t clen = canonical.len;
    TEST_ASSERT(strlen(future_prompt) > clen);
    TEST_ASSERT(!memcmp(future_prompt, canonical.ptr, clen));

    /* And what comes after is the new user turn + assistant prefix */
    const char *rest = future_prompt + clen;
    TEST_ASSERT(strstr(rest, "Thanks!") != NULL);
    TEST_ASSERT(strstr(rest, "<think>") != NULL);  /* new turn starts thinking */

    /* Verify reasoning is NOT in the future prompt for this turn */
    const char *asst_turn = strstr(future_prompt, "<" "\xef\xbd\x9c" "Assistant" "\xef\xbd\x9c" ">");
    TEST_ASSERT(asst_turn != NULL);
    TEST_ASSERT(strstr(future_prompt, reasoning) == NULL);  /* reasoning dropped */
```

<｜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_server.c

```c
strlen(prompt_text);
    TEST_ASSERT(pt_len >= 7);
    TEST_ASSERT(!memcmp(prompt_text + pt_len - 7, "<think>", 7));

    /* The model generates: reasoning + </think> + content */
    const char *reasoning = "Let me think... 2+2 = 4";
    const char *content = "The answer is 4.";

    /* Build the canonical checkpoint text (what we'd produce after canonicalization) */
    buf canonical = {0};
    buf_append(&canonical, prompt_text, pt_len - 7);  /* strip <think> */
    buf_puts(&canonical, "</think>");
    buf_puts(&canonical, content);
    buf_puts(&canonical, "<" "\xef\xbd\x9c" "end" "\xe2\x96\x81" "of" "\xe2\x96\x81" "sentence" "\xef\xbd\x9c" ">");

    request r;
    request_init(&r, REQ_CHAT, 128);
    r.think_mode = DS4_THINK_HIGH;
    r.prompt_text = xstrdup(prompt_text);
    char *visible = build_toolless_thinking_visible_text(&r, content);
    TEST_ASSERT(visible != NULL);
    TEST_ASSERT(!strcmp(visible, canonical.ptr));
    free(visible);
    request_free(&r);

    /* Now build what the NEXT request would render: history includes this
     * assistant message, plus a new user message.  Extract just the prefix
     * up to and including the eos of the assistant turn. */
    chat_msgs history_msgs = {0};
    chat_msg h_user1 = {0};
    h_user1.role = xstrdup("user");
    h_user1.content = xstrdup("What is 2+2?");
    chat_msgs_push(&history_msgs, h_user1);
    chat_msg h_asst = {0};
    h_asst.role = xstrdup("assistant");
    h_asst.reasoning = xstrdup(reasoning);
    h_asst.content = xstrdup(content);
    chat_msgs_push(&history_msgs, h_asst);
    chat_msg h_user2 = {0};
    h_user2.role = xstrdup("user");
    h_user2.content = xstrdup("Thanks!");
    chat_msgs_push(&history_msgs, h_user2);

    char *future_prompt = render_chat_prompt_text(&history_msgs, NULL, NULL, DS4_THINK_HIGH);

    /* The future prompt should START with our canonical text */
    size_t clen = canonical.len;
    TEST_ASSERT(strlen(future_prompt) > clen);
    TEST_ASSERT(!memcmp(future_prompt, canonical.ptr, clen));

    /* And what comes after is the new user turn + assistant prefix */
    const char *rest = future_prompt + clen;
    TEST_ASSERT(strstr(rest, "Thanks!") != NULL);
    TEST_ASSERT(strstr(rest, "<think>") != NULL);  /* new turn starts thinking */

    /* Verify reasoning is NOT in the future prompt for this turn */
    const char *asst_turn = strstr(future_prompt, "<" "\xef\xbd\x9c" "Assistant" "\xef\xbd\x9c" ">");
    TEST_ASSERT(asst_turn != NULL);
    TEST_ASSERT(strstr(future_prompt, reasoning) == NULL);  /* reasoning dropped */
```<｜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_server.c

```c
OL_NAME2\">\n"
        "...\n"
        "</｜DSML｜invoke>\n"
        "</｜DSML｜tool_calls>\n\n"
        "String parameters should be specified as raw text and set `string=\"true\"`. "
        "Preserve characters such as `>`, `&`, and `&&` exactly; never replace normal string characters with XML or HTML entity escapes. "
        "Only if a string value itself contains the exact closing parameter tag `</｜DSML｜parameter>`, write that tag as `</｜DSML｜parameter>` inside the value. "
        "For all other types (numbers, booleans, arrays, objects), pass the value in JSON format and set `string=\"false\"`.\n\n"
        "If thinking_mode is enabled (triggered by <think>), you MUST output your complete reasoning inside <think>...</think> BEFORE any tool calls or final response.\n\n"
        "Otherwise, output directly after </think> with tool calls or final response.\n\n"
        "### Available Tool Schemas\n\n");
    buf_puts(b, tool_schemas);
    buf_puts(b, "\n\nYou MUST strictly follow the above defined tool name and parameter schemas to invoke tool calls. "
                "Use the exact parameter names from the schemas.");
}

static void json_escape(buf *b, const char *s);

typedef struct {
    char *key;
    char *value;
    bool is_string;
    bool used;
} json_arg;

typedef struct {
    json_arg *v;
    int len;
    int cap;
} json_args;

static void json_args_free(json_args *args) {
    for (int i = 0; i < args->len; i++) {
        free(args->v[i].key);
        free(args->v[i].value);
    }
    free(args->v);
    memset(args, 0, sizeof(*args));
}

static void json_args_push(json_args *args, json_arg arg) {
    if (args->len == args->cap) {
        args->cap = args->cap ? args->cap * 2 : 8;
        args->v = xrealloc(args->v, (size_t)args->cap * sizeof(args->v[0]));
    }
    args->v[args->len++] = arg;
}

static int json_args_find_unused(json_args *args, const char *key) {
    if (!key) return -1;
    for (int i = 0; i < args->len; i++) {
        if (!args->v[i].used && args->v[i].key && !strcmp(args->v[i].key, key)) return i;
    }
    return -1;
}

static bool json_args_parse(const char *json, json_args *args) {
    const char *p = json ? json : "";
    json_ws(&p);
    if (*p != '{') return false;
    p++;
    json_ws(&p);
    while (*p && *p != '}') {
        bool is_string = false;
        char *key = NULL;
        char *value = NULL;
        if (!json_string(&p, &key)) goto bad;
        json_ws(&p);
        if (*p != ':') goto bad;
        p++;
        json_ws(&p);
        if (*p == '"') {
            is_string = true;
```

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

File: ds4_server.c

```c
OL_NAME2\">\n"
        "...\n"
        "</｜DSML｜invoke>\n"
        "</｜DSML｜tool_calls>\n\n"
        "String parameters should be specified as raw text and set `string=\"true\"`. "
        "Preserve characters such as `>`, `&`, and `&&` exactly; never replace normal string characters with XML or HTML entity escapes. "
        "Only if a string value itself contains the exact closing parameter tag `</｜DSML｜parameter>`, write that tag as `</｜DSML｜parameter>` inside the value. "
        "For all other types (numbers, booleans, arrays, objects), pass the value in JSON format and set `string=\"false\"`.\n\n"
        "If thinking_mode is enabled (triggered by <think>), you MUST output your complete reasoning inside <think>...</think> BEFORE any tool calls or final response.\n\n"
        "Otherwise, output directly after </think> with tool calls or final response.\n\n"
        "### Available Tool Schemas\n\n");
    buf_puts(b, tool_schemas);
    buf_puts(b, "\n\nYou MUST strictly follow the above defined tool name and parameter schemas to invoke tool calls. "
                "Use the exact parameter names from the schemas.");
}

static void json_escape(buf *b, const char *s);

typedef struct {
    char *key;
    char *value;
    bool is_string;
    bool used;
} json_arg;

typedef struct {
    json_arg *v;
    int len;
    int cap;
} json_args;

static void json_args_free(json_args *args) {
    for (int i = 0; i < args->len; i++) {
        free(args->v[i].key);
        free(args->v[i].value);
    }
    free(args->v);
    memset(args, 0, sizeof(*args));
}

static void json_args_push(json_args *args, json_arg arg) {
    if (args->len == args->cap) {
        args->cap = args->cap ? args->cap * 2 : 8;
        args->v = xrealloc(args->v, (size_t)args->cap * sizeof(args->v[0]));
    }
    args->v[args->len++] = arg;
}

static int json_args_find_unused(json_args *args, const char *key) {
    if (!key) return -1;
    for (int i = 0; i < args->len; i++) {
        if (!args->v[i].used && args->v[i].key && !strcmp(args->v[i].key, key)) return i;
    }
    return -1;
}

static bool json_args_parse(const char *json, json_args *args) {
    const char *p = json ? json : "";
    json_ws(&p);
    if (*p != '{') return false;
    p++;
    json_ws(&p);
    while (*p && *p != '}') {
        bool is_string = false;
        char *key = NULL;
        char *value = NULL;
        if (!json_string(&p, &key)) goto bad;
        json_ws(&p);
        if (*p != ':') goto bad;
        p++;
        json_ws(&p);
        if (*p == '"') {
            is_string = true;
```<｜Assistant｜></think>


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

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

File: ds4_server.c

```c
OL_NAME2\">\n"
        "...\n"
        "</｜DSML｜invoke>\n"
        "</｜DSML｜tool_calls>\n\n"
        "String parameters should be specified as raw text and set `string=\"true\"`. "
        "Preserve characters such as `>`, `&`, and `&&` exactly; never replace normal string characters with XML or HTML entity escapes. "
        "Only if a string value itself contains the exact closing parameter tag `</｜DSML｜parameter>`, write that tag as `</｜DSML｜parameter>` inside the value. "
        "For all other types (numbers, booleans, arrays, objects), pass the value in JSON format and set `string=\"false\"`.\n\n"
        "If thinking_mode is enabled (triggered by <think>), you MUST output your complete reasoning inside <think>...</think> BEFORE any tool calls or final response.\n\n"
        "Otherwise, output directly after </think> with tool calls or final response.\n\n"
        "### Available Tool Schemas\n\n");
    buf_puts(b, tool_schemas);
    buf_puts(b, "\n\nYou MUST strictly follow the above defined tool name and parameter schemas to invoke tool calls. "
                "Use the exact parameter names from the schemas.");
}

static void json_escape(buf *b, const char *s);

typedef struct {
    char *key;
    char *value;
    bool is_string;
    bool used;
} json_arg;

typedef struct {
    json_arg *v;
    int len;
    int cap;
} json_args;

static void json_args_free(json_args *args) {
    for (int i = 0; i < args->len; i++) {
        free(args->v[i].key);
        free(args->v[i].value);
    }
    free(args->v);
    memset(args, 0, sizeof(*args));
}

static void json_args_push(json_args *args, json_arg arg) {
    if (args->len == args->cap) {
        args->cap = args->cap ? args->cap * 2 : 8;
        args->v = xrealloc(args->v, (size_t)args->cap * sizeof(args->v[0]));
    }
    args->v[args->len++] = arg;
}

static int json_args_find_unused(json_args *args, const char *key) {
    if (!key) return -1;
    for (int i = 0; i < args->len; i++) {
        if (!args->v[i].used && args->v[i].key && !strcmp(args->v[i].key, key)) return i;
    }
    return -1;
}

static bool json_args_parse(const char *json, json_args *args) {
    const char *p = json ? json : "";
    json_ws(&p);
    if (*p != '{') return false;
    p++;
    json_ws(&p);
    while (*p && *p != '}') {
        bool is_string = false;
        char *key = NULL;
        char *value = NULL;
        if (!json_string(&p, &key)) goto bad;
        json_ws(&p);
        if (*p != ':') goto bad;
        p++;
        json_ws(&p);
        if (*p == '"') {
            is_string = true;
```

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

File: ds4_server.c

```c
OL_NAME2\">\n"
        "...\n"
        "</｜DSML｜invoke>\n"
        "</｜DSML｜tool_calls>\n\n"
        "String parameters should be specified as raw text and set `string=\"true\"`. "
        "Preserve characters such as `>`, `&`, and `&&` exactly; never replace normal string characters with XML or HTML entity escapes. "
        "Only if a string value itself contains the exact closing parameter tag `</｜DSML｜parameter>`, write that tag as `</｜DSML｜parameter>` inside the value. "
        "For all other types (numbers, booleans, arrays, objects), pass the value in JSON format and set `string=\"false\"`.\n\n"
        "If thinking_mode is enabled (triggered by <think>), you MUST output your complete reasoning inside <think>...</think> BEFORE any tool calls or final response.\n\n"
        "Otherwise, output directly after </think> with tool calls or final response.\n\n"
        "### Available Tool Schemas\n\n");
    buf_puts(b, tool_schemas);
    buf_puts(b, "\n\nYou MUST strictly follow the above defined tool name and parameter schemas to invoke tool calls. "
                "Use the exact parameter names from the schemas.");
}

static void json_escape(buf *b, const char *s);

typedef struct {
    char *key;
    char *value;
    bool is_string;
    bool used;
} json_arg;

typedef struct {
    json_arg *v;
    int len;
    int cap;
} json_args;

static void json_args_free(json_args *args) {
    for (int i = 0; i < args->len; i++) {
        free(args->v[i].key);
        free(args->v[i].value);
    }
    free(args->v);
    memset(args, 0, sizeof(*args));
}

static void json_args_push(json_args *args, json_arg arg) {
    if (args->len == args->cap) {
        args->cap = args->cap ? args->cap * 2 : 8;
        args->v = xrealloc(args->v, (size_t)args->cap * sizeof(args->v[0]));
    }
    args->v[args->len++] = arg;
}

static int json_args_find_unused(json_args *args, const char *key) {
    if (!key) return -1;
    for (int i = 0; i < args->len; i++) {
        if (!args->v[i].used && args->v[i].key && !strcmp(args->v[i].key, key)) return i;
    }
    return -1;
}

static bool json_args_parse(const char *json, json_args *args) {
    const char *p = json ? json : "";
    json_ws(&p);
    if (*p != '{') return false;
    p++;
    json_ws(&p);
    while (*p && *p != '}') {
        bool is_string = false;
        char *key = NULL;
        char *value = NULL;
        if (!json_string(&p, &key)) goto bad;
        json_ws(&p);
        if (*p != ':') goto bad;
        p++;
        json_ws(&p);
        if (*p == '"') {
            is_string = true;
```<｜Assistant｜><think>


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

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

File: ds4_server.c

```c
prompt, "<" "\xef\xbd\x9c" "Assistant" "\xef\xbd\x9c" ">");
    TEST_ASSERT(asst_turn != NULL);
    TEST_ASSERT(strstr(future_prompt, reasoning) == NULL);  /* reasoning dropped */

    free(future_prompt);
    buf_free(&canonical);
    free(prompt_text);
    chat_msgs_free(&prefix_msgs);
    chat_msgs_free(&history_msgs);
}

static void test_thinking_canonical_empty_content(void) {
    /* Edge case: model thinks but produces empty content (e.g. tool-less
     * thinking where answer is entirely in reasoning).  Canonical should
     * still be valid: prompt_text[:-7] + "</think><|eos|>" */
    chat_msgs msgs = {0};
    chat_msg user = {0};
    user.role = xstrdup("user");
    user.content = xstrdup("Think about life");
    chat_msgs_push(&msgs, user);

    char *prompt_text = render_chat_prompt_text(&msgs, NULL, NULL, DS4_THINK_HIGH);
    size_t pt_len = strlen(prompt_text);

    /* Build canonical with empty content */
    buf canonical = {0};
    buf_append(&canonical, prompt_text, pt_len - 7);
    buf_puts(&canonical, "</think>");
    /* empty content */
    buf_puts(&canonical, "<" "\xef\xbd\x9c" "end" "\xe2\x96\x81" "of" "\xe2\x96\x81" "sentence" "\xef\xbd\x9c" ">");

    /* Future prompt with empty content assistant message */
    chat_msgs history = {0};
    chat_msg h_u = {0};
    h_u.role = xstrdup("user");
    h_u.content = xstrdup("Think about life");
    chat_msgs_push(&history, h_u);
    chat_msg h_a = {0};
    h_a.role = xstrdup("assistant");
    h_a.reasoning = xstrdup("Deep thoughts about existence...");
    h_a.content = xstrdup("");
    chat_msgs_push(&history, h_a);
    chat_msg h_u2 = {0};
    h_u2.role = xstrdup("user");
    h_u2.content = xstrdup("Continue");
    chat_msgs_push(&history, h_u2);

    char *future = render_chat_prompt_text(&history, NULL, NULL, DS4_THINK_HIGH);
    TEST_ASSERT(strlen(future) > canonical.len);
    TEST_ASSERT(!memcmp(future, canonical.ptr, canonical.len));
    /* reasoning dropped */
    TEST_ASSERT(strstr(future, "Deep thoughts") == NULL);

    free(future);
    buf_free(&canonical);
    free(prompt_text);
    chat_msgs_free(&msgs);
    chat_msgs_free(&history);
}

static void test_thinking_canonical_multi_turn(void) {
    /* Multi-turn: 3 user messages, 2 assistant responses with reasoning.
     * Both prior assistant turns should have reasoning dropped.
     * The canonical after the SECOND generation should produce text that
     * matches the start of a 3rd-turn future prompt. */
    chat_msgs turn2_prefix = {0};
    chat_msg u1 = {0};
    u1.role = xstrdup("user");
```

<｜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_server.c

```c
prompt, "<" "\xef\xbd\x9c" "Assistant" "\xef\xbd\x9c" ">");
    TEST_ASSERT(asst_turn != NULL);
    TEST_ASSERT(strstr(future_prompt, reasoning) == NULL);  /* reasoning dropped */

    free(future_prompt);
    buf_free(&canonical);
    free(prompt_text);
    chat_msgs_free(&prefix_msgs);
    chat_msgs_free(&history_msgs);
}

static void test_thinking_canonical_empty_content(void) {
    /* Edge case: model thinks but produces empty content (e.g. tool-less
     * thinking where answer is entirely in reasoning).  Canonical should
     * still be valid: prompt_text[:-7] + "</think><|eos|>" */
    chat_msgs msgs = {0};
    chat_msg user = {0};
    user.role = xstrdup("user");
    user.content = xstrdup("Think about life");
    chat_msgs_push(&msgs, user);

    char *prompt_text = render_chat_prompt_text(&msgs, NULL, NULL, DS4_THINK_HIGH);
    size_t pt_len = strlen(prompt_text);

    /* Build canonical with empty content */
    buf canonical = {0};
    buf_append(&canonical, prompt_text, pt_len - 7);
    buf_puts(&canonical, "</think>");
    /* empty content */
    buf_puts(&canonical, "<" "\xef\xbd\x9c" "end" "\xe2\x96\x81" "of" "\xe2\x96\x81" "sentence" "\xef\xbd\x9c" ">");

    /* Future prompt with empty content assistant message */
    chat_msgs history = {0};
    chat_msg h_u = {0};
    h_u.role = xstrdup("user");
    h_u.content = xstrdup("Think about life");
    chat_msgs_push(&history, h_u);
    chat_msg h_a = {0};
    h_a.role = xstrdup("assistant");
    h_a.reasoning = xstrdup("Deep thoughts about existence...");
    h_a.content = xstrdup("");
    chat_msgs_push(&history, h_a);
    chat_msg h_u2 = {0};
    h_u2.role = xstrdup("user");
    h_u2.content = xstrdup("Continue");
    chat_msgs_push(&history, h_u2);

    char *future = render_chat_prompt_text(&history, NULL, NULL, DS4_THINK_HIGH);
    TEST_ASSERT(strlen(future) > canonical.len);
    TEST_ASSERT(!memcmp(future, canonical.ptr, canonical.len));
    /* reasoning dropped */
    TEST_ASSERT(strstr(future, "Deep thoughts") == NULL);

    free(future);
    buf_free(&canonical);
    free(prompt_text);
    chat_msgs_free(&msgs);
    chat_msgs_free(&history);
}

static void test_thinking_canonical_multi_turn(void) {
    /* Multi-turn: 3 user messages, 2 assistant responses with reasoning.
     * Both prior assistant turns should have reasoning dropped.
     * The canonical after the SECOND generation should produce text that
     * matches the start of a 3rd-turn future prompt. */
    chat_msgs turn2_prefix = {0};
    chat_msg u1 = {0};
    u1.role = xstrdup("user");
```<｜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_server.c

```c
prompt, "<" "\xef\xbd\x9c" "Assistant" "\xef\xbd\x9c" ">");
    TEST_ASSERT(asst_turn != NULL);
    TEST_ASSERT(strstr(future_prompt, reasoning) == NULL);  /* reasoning dropped */

    free(future_prompt);
    buf_free(&canonical);
    free(prompt_text);
    chat_msgs_free(&prefix_msgs);
    chat_msgs_free(&history_msgs);
}

static void test_thinking_canonical_empty_content(void) {
    /* Edge case: model thinks but produces empty content (e.g. tool-less
     * thinking where answer is entirely in reasoning).  Canonical should
     * still be valid: prompt_text[:-7] + "</think><|eos|>" */
    chat_msgs msgs = {0};
    chat_msg user = {0};
    user.role = xstrdup("user");
    user.content = xstrdup("Think about life");
    chat_msgs_push(&msgs, user);

    char *prompt_text = render_chat_prompt_text(&msgs, NULL, NULL, DS4_THINK_HIGH);
    size_t pt_len = strlen(prompt_text);

    /* Build canonical with empty content */
    buf canonical = {0};
    buf_append(&canonical, prompt_text, pt_len - 7);
    buf_puts(&canonical, "</think>");
    /* empty content */
    buf_puts(&canonical, "<" "\xef\xbd\x9c" "end" "\xe2\x96\x81" "of" "\xe2\x96\x81" "sentence" "\xef\xbd\x9c" ">");

    /* Future prompt with empty content assistant message */
    chat_msgs history = {0};
    chat_msg h_u = {0};
    h_u.role = xstrdup("user");
    h_u.content = xstrdup("Think about life");
    chat_msgs_push(&history, h_u);
    chat_msg h_a = {0};
    h_a.role = xstrdup("assistant");
    h_a.reasoning = xstrdup("Deep thoughts about existence...");
    h_a.content = xstrdup("");
    chat_msgs_push(&history, h_a);
    chat_msg h_u2 = {0};
    h_u2.role = xstrdup("user");
    h_u2.content = xstrdup("Continue");
    chat_msgs_push(&history, h_u2);

    char *future = render_chat_prompt_text(&history, NULL, NULL, DS4_THINK_HIGH);
    TEST_ASSERT(strlen(future) > canonical.len);
    TEST_ASSERT(!memcmp(future, canonical.ptr, canonical.len));
    /* reasoning dropped */
    TEST_ASSERT(strstr(future, "Deep thoughts") == NULL);

    free(future);
    buf_free(&canonical);
    free(prompt_text);
    chat_msgs_free(&msgs);
    chat_msgs_free(&history);
}

static void test_thinking_canonical_multi_turn(void) {
    /* Multi-turn: 3 user messages, 2 assistant responses with reasoning.
     * Both prior assistant turns should have reasoning dropped.
     * The canonical after the SECOND generation should produce text that
     * matches the start of a 3rd-turn future prompt. */
    chat_msgs turn2_prefix = {0};
    chat_msg u1 = {0};
    u1.role = xstrdup("user");
```

<｜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_server.c

```c
prompt, "<" "\xef\xbd\x9c" "Assistant" "\xef\xbd\x9c" ">");
    TEST_ASSERT(asst_turn != NULL);
    TEST_ASSERT(strstr(future_prompt, reasoning) == NULL);  /* reasoning dropped */

    free(future_prompt);
    buf_free(&canonical);
    free(prompt_text);
    chat_msgs_free(&prefix_msgs);
    chat_msgs_free(&history_msgs);
}

static void test_thinking_canonical_empty_content(void) {
    /* Edge case: model thinks but produces empty content (e.g. tool-less
     * thinking where answer is entirely in reasoning).  Canonical should
     * still be valid: prompt_text[:-7] + "</think><|eos|>" */
    chat_msgs msgs = {0};
    chat_msg user = {0};
    user.role = xstrdup("user");
    user.content = xstrdup("Think about life");
    chat_msgs_push(&msgs, user);

    char *prompt_text = render_chat_prompt_text(&msgs, NULL, NULL, DS4_THINK_HIGH);
    size_t pt_len = strlen(prompt_text);

    /* Build canonical with empty content */
    buf canonical = {0};
    buf_append(&canonical, prompt_text, pt_len - 7);
    buf_puts(&canonical, "</think>");
    /* empty content */
    buf_puts(&canonical, "<" "\xef\xbd\x9c" "end" "\xe2\x96\x81" "of" "\xe2\x96\x81" "sentence" "\xef\xbd\x9c" ">");

    /* Future prompt with empty content assistant message */
    chat_msgs history = {0};
    chat_msg h_u = {0};
    h_u.role = xstrdup("user");
    h_u.content = xstrdup("Think about life");
    chat_msgs_push(&history, h_u);
    chat_msg h_a = {0};
    h_a.role = xstrdup("assistant");
    h_a.reasoning = xstrdup("Deep thoughts about existence...");
    h_a.content = xstrdup("");
    chat_msgs_push(&history, h_a);
    chat_msg h_u2 = {0};
    h_u2.role = xstrdup("user");
    h_u2.content = xstrdup("Continue");
    chat_msgs_push(&history, h_u2);

    char *future = render_chat_prompt_text(&history, NULL, NULL, DS4_THINK_HIGH);
    TEST_ASSERT(strlen(future) > canonical.len);
    TEST_ASSERT(!memcmp(future, canonical.ptr, canonical.len));
    /* reasoning dropped */
    TEST_ASSERT(strstr(future, "Deep thoughts") == NULL);

    free(future);
    buf_free(&canonical);
    free(prompt_text);
    chat_msgs_free(&msgs);
    chat_msgs_free(&history);
}

static void test_thinking_canonical_multi_turn(void) {
    /* Multi-turn: 3 user messages, 2 assistant responses with reasoning.
     * Both prior assistant turns should have reasoning dropped.
     * The canonical after the SECOND generation should produce text that
     * matches the start of a 3rd-turn future prompt. */
    chat_msgs turn2_prefix = {0};
    chat_msg u1 = {0};
    u1.role = xstrdup("user");
```<｜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_server.c

```c
generation should produce text that
     * matches the start of a 3rd-turn future prompt. */
    chat_msgs turn2_prefix = {0};
    chat_msg u1 = {0};
    u1.role = xstrdup("user");
    u1.content = xstrdup("Hello");
    chat_msgs_push(&turn2_prefix, u1);
    chat_msg a1 = {0};
    a1.role = xstrdup("assistant");
    a1.reasoning = xstrdup("first reasoning");
    a1.content = xstrdup("Hi there");
    chat_msgs_push(&turn2_prefix, a1);
    chat_msg u2 = {0};
    u2.role = xstrdup("user");
    u2.content = xstrdup("How are you?");
    chat_msgs_push(&turn2_prefix, u2);

    /* prompt_text for the 2nd generation (includes 1st assistant turn) */
    char *prompt_text = render_chat_prompt_text(&turn2_prefix, NULL, NULL, DS4_THINK_HIGH);
    size_t pt_len = strlen(prompt_text);
    TEST_ASSERT(!memcmp(prompt_text + pt_len - 7, "<think>", 7));

    /* 1st turn reasoning is already dropped in this prompt_text */
    TEST_ASSERT(strstr(prompt_text, "first reasoning") == NULL);
    TEST_ASSERT(strstr(prompt_text, "Hi there") != NULL);

    /* After 2nd generation: canonical drops 2nd reasoning too */
    const char *content2 = "I'm doing well";
    buf canonical = {0};
    buf_append(&canonical, prompt_text, pt_len - 7);
    buf_puts(&canonical, "</think>");
    buf_puts(&canonical, content2);
    buf_puts(&canonical, "<" "\xef\xbd\x9c" "end" "\xe2\x96\x81" "of" "\xe2\x96\x81" "sentence" "\xef\xbd\x9c" ">");

    /* Future: 3rd user message arrives */
    chat_msgs future_msgs = {0};
    chat_msg fu1 = {0}; fu1.role = xstrdup("user"); fu1.content = xstrdup("Hello");
    chat_msgs_push(&future_msgs, fu1);
    chat_msg fa1 = {0}; fa1.role = xstrdup("assistant");
    fa1.reasoning = xstrdup("first reasoning");
    fa1.content = xstrdup("Hi there");
    chat_msgs_push(&future_msgs, fa1);
    chat_msg fu2 = {0}; fu2.role = xstrdup("user"); fu2.content = xstrdup("How are you?");
    chat_msgs_push(&future_msgs, fu2);
    chat_msg fa2 = {0}; fa2.role = xstrdup("assistant");
    fa2.reasoning = xstrdup("second reasoning");
    fa2.content = xstrdup(content2);
    chat_msgs_push(&future_msgs, fa2);
    chat_msg fu3 = {0}; fu3.role = xstrdup("user"); fu3.content = xstrdup("Great");
    chat_msgs_push(&future_msgs, fu3);

    char *future = render_chat_prompt_text(&future_msgs, NULL, NULL, DS4_THINK_HIGH);
    /* Both reasonings dropped */
    TEST_ASSERT(strstr(future, "first reasoning") == NULL);
    TEST_ASSERT(strstr(future, "second reasoning") == NULL);
    /* Canonical is a prefix of future */
    TEST_ASSERT(strlen(future) > canonical.len);
```

<｜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_server.c

```c
generation should produce text that
     * matches the start of a 3rd-turn future prompt. */
    chat_msgs turn2_prefix = {0};
    chat_msg u1 = {0};
    u1.role = xstrdup("user");
    u1.content = xstrdup("Hello");
    chat_msgs_push(&turn2_prefix, u1);
    chat_msg a1 = {0};
    a1.role = xstrdup("assistant");
    a1.reasoning = xstrdup("first reasoning");
    a1.content = xstrdup("Hi there");
    chat_msgs_push(&turn2_prefix, a1);
    chat_msg u2 = {0};
    u2.role = xstrdup("user");
    u2.content = xstrdup("How are you?");
    chat_msgs_push(&turn2_prefix, u2);

    /* prompt_text for the 2nd generation (includes 1st assistant turn) */
    char *prompt_text = render_chat_prompt_text(&turn2_prefix, NULL, NULL, DS4_THINK_HIGH);
    size_t pt_len = strlen(prompt_text);
    TEST_ASSERT(!memcmp(prompt_text + pt_len - 7, "<think>", 7));

    /* 1st turn reasoning is already dropped in this prompt_text */
    TEST_ASSERT(strstr(prompt_text, "first reasoning") == NULL);
    TEST_ASSERT(strstr(prompt_text, "Hi there") != NULL);

    /* After 2nd generation: canonical drops 2nd reasoning too */
    const char *content2 = "I'm doing well";
    buf canonical = {0};
    buf_append(&canonical, prompt_text, pt_len - 7);
    buf_puts(&canonical, "</think>");
    buf_puts(&canonical, content2);
    buf_puts(&canonical, "<" "\xef\xbd\x9c" "end" "\xe2\x96\x81" "of" "\xe2\x96\x81" "sentence" "\xef\xbd\x9c" ">");

    /* Future: 3rd user message arrives */
    chat_msgs future_msgs = {0};
    chat_msg fu1 = {0}; fu1.role = xstrdup("user"); fu1.content = xstrdup("Hello");
    chat_msgs_push(&future_msgs, fu1);
    chat_msg fa1 = {0}; fa1.role = xstrdup("assistant");
    fa1.reasoning = xstrdup("first reasoning");
    fa1.content = xstrdup("Hi there");
    chat_msgs_push(&future_msgs, fa1);
    chat_msg fu2 = {0}; fu2.role = xstrdup("user"); fu2.content = xstrdup("How are you?");
    chat_msgs_push(&future_msgs, fu2);
    chat_msg fa2 = {0}; fa2.role = xstrdup("assistant");
    fa2.reasoning = xstrdup("second reasoning");
    fa2.content = xstrdup(content2);
    chat_msgs_push(&future_msgs, fa2);
    chat_msg fu3 = {0}; fu3.role = xstrdup("user"); fu3.content = xstrdup("Great");
    chat_msgs_push(&future_msgs, fu3);

    char *future = render_chat_prompt_text(&future_msgs, NULL, NULL, DS4_THINK_HIGH);
    /* Both reasonings dropped */
    TEST_ASSERT(strstr(future, "first reasoning") == NULL);
    TEST_ASSERT(strstr(future, "second reasoning") == NULL);
    /* Canonical is a prefix of future */
    TEST_ASSERT(strlen(future) > canonical.len);
```<｜Assistant｜></think>