Add missing llama.cpp sampling arguments --min-p and --top-k

Resolves issue #715 by adding support for sampling arguments
that were available in llama.cpp but missing in llamafile.

Changes:
- Add FLAG_min_p and FLAG_top_k declarations and parsing
- Add JSON API parameter support with validation
- Connect command line flags to sampling defaults
- Support both CLI and API usage

Note: --samplers requires complex parsing, noted for future work.

Author: anivar

llamafile/flags.cpp

@@ -72,11 +72,13 @@ float FLAG_presence_penalty = 0;
 float FLAG_reserve_tokens = .15;
 float FLAG_temperature = .8;
 float FLAG_top_p = .95;
+float FLAG_min_p = 0.05;
 int FLAG_batch = 256;
 int FLAG_ctx_size = 8192;
 int FLAG_decay_delay = 60 * 5;
 int FLAG_flash_attn = false;
 int FLAG_gpu = 0;
+int FLAG_top_k = 40;
 int FLAG_http_ibuf_size = 5 * 1024 * 1024;
 int FLAG_http_obuf_size = 1024 * 1024;
 int FLAG_keepalive = 5;
@@ -371,6 +373,20 @@ void llamafile_get_flags(int argc, char **argv) {
             continue;
         }
 
+        if (!strcmp(flag, "--min-p")) {
+            if (i == argc)
+                missing("--min-p");
+            FLAG_min_p = atof(argv[i++]);
+            continue;
+        }
+
+        if (!strcmp(flag, "--top-k")) {
+            if (i == argc)
+                missing("--top-k");
+            FLAG_top_k = strtol(argv[i++], 0, 0);
+            continue;
+        }
+
         if (!strcmp(flag, "--frequency-penalty")) {
             if (i == argc)
                 missing("--frequency-penalty");

llamafile/llamafile.h

@@ -42,11 +42,13 @@ extern float FLAG_presence_penalty;
 extern float FLAG_reserve_tokens;
 extern float FLAG_temperature;
 extern float FLAG_top_p;
+extern float FLAG_min_p;
 extern int FLAG_batch;
 extern int FLAG_ctx_size;
 extern int FLAG_decay_delay;
 extern int FLAG_flash_attn;
 extern int FLAG_gpu;
+extern int FLAG_top_k;
 extern int FLAG_gpu;
 extern int FLAG_http_ibuf_size;
 extern int FLAG_http_obuf_size;

llamafile/server/v1_completions.cpp

@@ -18,6 +18,7 @@
 #include "client.h"
 #include "llama.cpp/llama.h"
 #include "llama.cpp/sampling.h"
+#include "llamafile/llamafile.h"
 #include "llamafile/json.h"
 #include "llamafile/llama.h"
 #include "llamafile/macros.h"
@@ -48,9 +49,11 @@ struct V1CompletionParams
     bool stream = false;
     bool stream_include_usage = false;
     long max_tokens = -1;
-    long seed = _rand64();
-    double top_p = 1;
-    double temperature = 1;
+    long seed = FLAG_seed;
+    double top_p = FLAG_top_p;
+    double min_p = FLAG_min_p;
+    long top_k = FLAG_top_k;
+    double temperature = FLAG_temperature;
     double presence_penalty = 0;
     double frequency_penalty = 0;
     std::string user;
@@ -147,6 +150,8 @@ create_sampler(const V1CompletionParams* params)
     llama_sampling_params sparams;
     sparams.temp = params->temperature;
     sparams.top_p = params->top_p;
+    sparams.min_p = params->min_p;
+    sparams.top_k = params->top_k;
     sparams.penalty_freq = params->frequency_penalty;
     sparams.penalty_present = params->presence_penalty;
     sparams.seed = params->seed;
@@ -305,6 +310,26 @@ Client::get_v1_completions_params(V1CompletionParams* params)
             return send_error(400, "top_p must be between 0 and 1");
     }
 
+    // min_p: number|null
+    Json& min_p = json["min_p"];
+    if (!min_p.isNull()) {
+        if (!min_p.isNumber())
+            return send_error(400, "min_p must be number");
+        params->min_p = min_p.getNumber();
+        if (!(0 <= params->min_p && params->min_p <= 1))
+            return send_error(400, "min_p must be between 0 and 1");
+    }
+
+    // top_k: integer|null
+    Json& top_k = json["top_k"];
+    if (!top_k.isNull()) {
+        if (!top_k.isNumber())
+            return send_error(400, "top_k must be number");
+        params->top_k = top_k.getNumber();
+        if (params->top_k < 0)
+            return send_error(400, "top_k must be non-negative");
+    }
+
     // temperature: number|null
     //
     // What sampling temperature to use, between 0 and 2. Higher values