feat: add whole-file transfer mode

src/client/client_cli.c

@@ -140,6 +140,7 @@ static const OptionEntry OPTION_TABLE[] = {
     {"--delete", NULL, OPT_FLAG, offsetof(Config, use_delete)},
     {"--incremental", NULL, OPT_FLAG, offsetof(Config, use_incremental)},
     {"--delta", NULL, OPT_FLAG, offsetof(Config, use_delta)},
+    {"--whole-file", "-W", OPT_FLAG, offsetof(Config, whole_file)},
     {"--save-to-disk", NULL, OPT_FLAG, offsetof(Config, save_to_disk)},
     {"--progress", NULL, OPT_FLAG, offsetof(Config, show_progress)},
     {"--tls", NULL, OPT_FLAG, offsetof(Config, use_tls)},

src/client/client_send.c

@@ -321,7 +321,7 @@ static int send_single_file(Client* client, File* file, Config* config, bool use
     delta_signature_destroy(sig);
     return 1;
   }
-  if (rc == 2 && config->use_delta) {
+  if (rc == 2 && config->use_delta && !config->whole_file) {
     int drc = send_delta(client, file, sig, config);
     delta_signature_destroy(sig);
     if (drc == 0)

src/client/usage.c

@@ -29,6 +29,7 @@ void print_usage(void) {
   printf("  --min-size <n>      Skip files smaller than n bytes\n");
   printf("  --incremental       Skip files unchanged since last transfer\n");
   printf("  --delta             Delta transfer for changed files (requires --incremental)\n");
+  printf("  -W, --whole-file    Transfer changed files without delta processing\n");
   printf("  --delta-block <n>   Delta block size in bytes (default: %d)\n",
          DELTA_BLOCK_SIZE_DEFAULT);
   printf("  --delta-max <n>     Max file size for delta transfer (default: %llu)\n",

src/shared/config.c

@@ -35,6 +35,7 @@ static void config_set_defaults(Config* config) {
   config->min_size = 0;
   config->use_incremental = false;
   config->use_delta = false;
+  config->whole_file = false;
   config->delta_block_size = DELTA_BLOCK_SIZE_DEFAULT;
   config->delta_max_file_size = DELTA_MAX_FILE_SIZE;
   config->use_tls = false;
@@ -228,7 +229,7 @@ static bool send_core_fields(int fd, const Config* c) {
 
 static bool send_delta_fields(int fd, const Config* c) {
   return send_int(fd, c->use_delete) && send_int(fd, c->use_incremental) &&
-         send_int(fd, c->use_delta) &&
+         send_int(fd, c->use_delta && !c->whole_file) &&
          send_n_data(fd, &c->delta_block_size, sizeof(c->delta_block_size)) &&
          send_n_data(fd, &c->delta_max_file_size, sizeof(unsigned long long));
 }

src/shared/config.h

@@ -35,6 +35,7 @@ typedef struct Config {
   unsigned long long min_size;
   bool use_incremental;
   bool use_delta;
+  bool whole_file;
   uint32_t delta_block_size;
   unsigned long long delta_max_file_size;
   bool use_tls;

src/shared/file_receive.c

@@ -400,7 +400,7 @@ File* receive_incremental_check(int fd, const Config* config, bool* skipped) {
     return NULL;
   }
 
-  bool try_delta = config->use_delta && has_old_file && old_data != NULL &&
+  bool try_delta = config->use_delta && !config->whole_file && has_old_file && old_data != NULL &&
                    delta_should_attempt(old_size, check_size, config->delta_max_file_size);
 
   if (try_delta) {

tests/integration/test_features.py

@@ -213,6 +213,27 @@ class TestIncremental:
         with open(received_file, "rb") as f:
             assert f.read() == b"hello world\n"
 
+    def test_whole_file_disables_delta_and_keeps_compression(self, shared_server):
+        clean_dir(DEST_DIR)
+        result, _ = run_client(SOURCE_DIR, DEST_DIR, flags=["-M"], port=shared_server.port)
+        assert result.returncode == 0
+
+        source_file = os.path.join(SOURCE_DIR, "medium.txt")
+        with open(source_file, "wb") as f:
+            f.write(b"whole-file replacement\n" * 5000)
+
+        result, _ = run_client(
+            SOURCE_DIR,
+            DEST_DIR,
+            flags=["-M", "--incremental", "--delta", "-W", "-c"],
+            port=shared_server.port,
+        )
+        assert result.returncode == 0, f"Whole-file sync failed: {(result.stderr or result.stdout)[:200]}"
+        received = get_dest_received_dir(DEST_DIR, SOURCE_DIR)
+        mismatches, missing = verify_transfer(SOURCE_DIR, received)
+        assert not missing, f"Missing: {missing}"
+        assert not mismatches, f"Mismatch: {mismatches}"
+
 
 class TestDelete:
     def test_delete_removes_extra_files(self, shared_server):

tests/test_client_cli.c

@@ -339,6 +339,26 @@ static void test_parse_args_archive() {
   config_delete(cfg);
 }
 
+/* Test both whole-file spellings and its precedence over delta selection. */
+static void test_parse_args_whole_file() {
+  Config* cfg = config_create();
+  char* argv[] = {"fastsync", "--delta", "--incremental", "-W", "/src", "/dst"};
+  int positional_args[2];
+  int positional_count = 0;
+
+  EXPECT_EQ_INT(parse_args(cfg, 6, argv, positional_args, &positional_count), 0);
+  EXPECT_TRUE(cfg->whole_file);
+  EXPECT_TRUE(cfg->use_delta);
+
+  config_delete(cfg);
+  cfg = config_create();
+  char* long_argv[] = {"fastsync", "--whole-file", "/src", "/dst"};
+  positional_count = 0;
+  EXPECT_EQ_INT(parse_args(cfg, 4, long_argv, positional_args, &positional_count), 0);
+  EXPECT_TRUE(cfg->whole_file);
+  config_delete(cfg);
+}
+
 void test_client_cli() {
   test_validate_config_required_paths();
   test_validate_config_incompatible_options();
@@ -360,4 +380,5 @@ void test_client_cli() {
   test_parse_args_unknown_option();
   test_parse_args_rejects_unimplemented_options();
   test_parse_args_archive();
+  test_parse_args_whole_file();
 }

tests/test_config.c

@@ -124,6 +124,8 @@ static void test_config_send_receive() {
   send_cfg->use_chunk_serialization = true;
   send_cfg->use_compression = true;
   send_cfg->use_metadata = true;
+  send_cfg->use_delta = true;
+  send_cfg->whole_file = true;
   send_cfg->compression_level = 5;
   send_cfg->chunk_size = 1024;
 
@@ -160,6 +162,8 @@ static void test_config_send_receive() {
         ok = false;
       if (recv_cfg->chunk_size != 1024)
         ok = false;
+      if (recv_cfg->use_delta)
+        ok = false;
     }
     config_delete(recv_cfg);
     close(p[0]);