diff --git a/README.md b/README.md
index 1386d72..cabb909 100644
--- a/README.md
+++ b/README.md
@@ -66,8 +66,9 @@ replacement for every rsync feature or protocol mode.
 - Owner/group, ACL, xattr, hard-link, device, and special-file handling is
   incomplete or unavailable.
 - Sparse-file handling does not yet preserve all holes correctly.
-- `--partial`, `--partial-dir`, `--append`, and `--append-verify` are not yet
-  full rsync-style resumable transfers.
+- `--partial`, `--partial-dir`, `-P`, `--append`, and `--append-verify` are not
+  yet full rsync-style resumable transfers. Interrupted files are not retained
+  for resumption.
 - Several rsync short options currently have FastSync-specific meanings. Do
   not assume every short option is interchangeable yet.
 
@@ -97,6 +98,7 @@ partial, alternate, and planned behavior.
 | `-v, --verbose` | Enable debug logging |
 | `-q, --quiet` | Suppress non-error output |
 | `--progress` | Show real-time transfer speed |
+| `-P` | Enables partial-transfer mode and progress output (partial retention is incomplete) |
 | `--delete` | Delete files on receiver not present in source |
 | `--exclude <pattern>` | Exclude files matching glob pattern (repeatable) |
 | `--exclude-from <file>` | Read exclude patterns from a file (one per line) |
diff --git a/RSYNC_COMPAT.md b/RSYNC_COMPAT.md
index d71a103..6204d3f 100644
--- a/RSYNC_COMPAT.md
+++ b/RSYNC_COMPAT.md
@@ -40,7 +40,7 @@ This document maps rsync's full feature set to FastSync's current implementation
 | `-h`, `--human-readable` | Human-readable numbers | ✅ Implemented | Formats transfer byte sizes using binary units |
 | `-i`, `--itemize-changes` | Per-file change summary | ❌ Not Implemented | Removed because it had no effect |
 | `--progress` | Show progress | ✅ Implemented | Progress callback in sender |
-| `-P` | Same as --partial --progress | ❌ Not Implemented | |
+| `-P` | Same as --partial --progress | ⚠️ Partial | Parses and enables progress, but interrupted files are not retained for resumable transfers |
 | `--out-format=FORMAT` | Custom output format | ❌ Not Implemented | Removed because it had no effect |
 | `--log-file=FILE` | Log to file | ✅ Implemented | `log_file` config field |
 | `--log-file-format=FMT` | Log format | ❌ Not Implemented | |
diff --git a/src/client/client_cli.c b/src/client/client_cli.c
index 770e815..4a3ca80 100644
--- a/src/client/client_cli.c
+++ b/src/client/client_cli.c
@@ -541,6 +541,11 @@ int parse_args(Config* config, int argc, char* argv[], int* positional_args,
   }
 
   for (int i = 1; i < argc; i++) {
+    if (strcmp(argv[i], "-P") == 0) {
+      config->partial = true;
+      config->show_progress = true;
+      continue;
+    }
     if (strncmp(argv[i], "--no-", strlen("--no-")) == 0) {
       if (apply_negation(config, argv[i]) != 0)
         return -1;
@@ -581,6 +586,7 @@ int parse_args(Config* config, int argc, char* argv[], int* positional_args,
       }
       continue;
     }
+
     const OptionEntry* entry = find_table_option(argv[i]);
     const char* inline_value = NULL;
     if (!entry)
diff --git a/src/client/usage.c b/src/client/usage.c
index f754440..94c9d4e 100644
--- a/src/client/usage.c
+++ b/src/client/usage.c
@@ -21,6 +21,7 @@ void print_usage(void) {
   printf("  --remove-source-files  Remove regular source files after successful transfer\n");
   printf("  -p <port>           SSH port (default: 22)\n");
   printf("  --progress          Show transfer progress\n");
+  printf("  -P                  Partial mode with progress (retention incomplete)\n");
   printf("  -8, --8-bit-output  Leave high-bit characters unescaped in output\n");
   printf("  --delete            Delete files on receiver not in source\n");
   printf("  --ignore-existing  Skip files that already exist on receiver\n");
diff --git a/tests/test_client_cli.c b/tests/test_client_cli.c
index 8dda975..435ffcc 100644
--- a/tests/test_client_cli.c
+++ b/tests/test_client_cli.c
@@ -928,6 +928,22 @@ static void test_parse_args_compression_aliases() {
   config_delete(cfg);
 }
 
+/* Test rsync-compatible -P parsing; resumable partial-file retention is not implied. */
+static void test_parse_args_partial_progress() {
+  Config* cfg = config_create();
+  char* argv[] = {"fastsync", "-P", "/src", "/dst"};
+  int positional_args[2];
+  int positional_count = 0;
+
+  int ret = parse_args(cfg, 4, argv, positional_args, &positional_count);
+  EXPECT_EQ_INT(ret, 0);
+  EXPECT_TRUE(cfg->partial);
+  EXPECT_TRUE(cfg->show_progress);
+  EXPECT_EQ_INT(positional_count, 2);
+
+  config_delete(cfg);
+}
+
 static void test_parse_args_compression_equals_and_none() {
   Config* cfg = config_create();
   char* argv[] = {"fastsync", "-z", "--zc=none", "--zl=7", "/src", "/dst"};
@@ -1043,7 +1059,7 @@ void test_client_cli() {
   test_parse_args_info_verbose_order();
   test_parse_args_rejects_invalid_info_flag();
   test_parse_args_archive();
-  test_parse_args_negations();
+test_parse_args_negations();
   test_parse_args_negation_order();
   test_parse_args_no_preserve_blocks_implicit_metadata();
   test_parse_args_rejects_unsafe_negation();
@@ -1063,4 +1079,5 @@ void test_client_cli() {
   test_parse_args_compression_alias_equals();
   test_parse_args_rejects_invalid_compression_level_equals();
   test_parse_args_rejects_invalid_compression_choice();
+  test_parse_args_partial_progress();
 }