feat(core/prodtest): allow alternative per-command CRC verification

diff --git a/core/embed/projects/prodtest/README.md b/core/embed/projects/prodtest/README.md
index 7abbc890..9973df4b 100644
--- a/core/embed/projects/prodtest/README.md
+++ b/core/embed/projects/prodtest/README.md
@@ -86,9 +86,9 @@ The CLI supports an optional CRC checksum for commands and responses to ensure d
 When CRC is enabled, every command MUST include a CRC-32 checksum at the end of the line, preceded by a space.
 
 Command Format:
-`<command> [<args>] <CRC32>`
+`<command> [<args>] <CRC32>` or `checked-<command> [<args> <CRC32>]`
 
-The checksum is calculated using the standard CRC-32 algorithm (polynomial `0xEDB88320`, initial value `0xFFFFFFFF`, and final XOR `0xFFFFFFFF`) over the command string excluding the ` <CRC32>` suffix.
+The checksum is calculated using the standard CRC-32 algorithm (polynomial `0xEDB88320`, initial value `0xFFFFFFFF`, and final XOR `0xFFFFFFFF`) over the command string excluding the checksum. In the `checked-<command> [<args> <CRC32>]` format, the `<CRC32>` is the checksum of the string starting after `checked-`.
 
 The device also appends the checksum to every response line (including `OK`, `ERROR`, `PROGRESS`, and `#` traces).
 
@@ -97,8 +97,19 @@ Response Format:
 
 Example with CRC enabled:
 ```
-ping ABC 70417631
-OK ABC E7193F16
+ping ABC 3240F7DC
+OK ABC 24DA4527
+```
+
+Example with `checked-` prefix (enforces CRC for a single command even if CRC is otherwise disabled):
+```
+checked-ping ABC 35F69145
+OK ABC 24DA4527
+```
+If the command has no arguments, the format is `checked-<command> <CRC32>`:
+```
+checked-ping D720F16C
+OK  D38BF920
 ```
 
 ## List of commands
diff --git a/core/embed/rtl/cli.c b/core/embed/rtl/cli.c
index 1ba64762..dab7433d 100644
--- a/core/embed/rtl/cli.c
+++ b/core/embed/rtl/cli.c
@@ -11,6 +11,9 @@
 #define ESC_COLOR_GRAY "\e[37m"
 #define ESC_COLOR_RESET "\e[39m"
 
+#define CLI_CRC_PREFIX "checked-"
+#define CLI_CRC_LENGTH 8
+
 #define CRC32_INITIAL 0xFFFFFFFF
 #define CRC32_POLYNOMIAL 0xEDB88320
 
@@ -229,9 +232,9 @@ void cli_abort(cli_t* cli) { cli->aborted = true; }
 
 bool cli_aborted(cli_t* cli) { return cli->aborted; }
 
-void cli_enable_crc(cli_t* cli) { cli->crc_req = true; }
+void cli_enable_crc(cli_t* cli) { cli->crc_auto = true; }
 
-void cli_disable_crc(cli_t* cli) { cli->crc_req = false; }
+void cli_disable_crc(cli_t* cli) { cli->crc_auto = false; }
 
 // Finds a command record by name
 //
@@ -541,6 +544,7 @@ static void cli_clear_line(cli_t* cli) {
   cli->hist_idx = 0;
   cli->hist_prefix = 0;
   cli->response_crc = CRC32_INITIAL;
+  cli->crc_req = cli->crc_auto;
   memset(cli->line_buffer, 0, sizeof(cli->line_buffer));
 }
 
@@ -570,6 +574,12 @@ static bool cli_split_args(cli_t* cli) {
   cli->cmd_name = cstr_token(&buf);
   cli->args_count = 0;
 
+  // Single crc check?
+  if (cstr_starts_with(cli->line_buffer, CLI_CRC_PREFIX)) {
+    cli->cmd_name += strlen(CLI_CRC_PREFIX);
+    cli->crc_req = true;
+  }
+
   while (*buf != '\0' && cli->args_count < CLI_MAX_ARGS) {
     const char* arg = cstr_token(&buf);
     if (*arg != '\0') {
@@ -623,39 +633,17 @@ const cli_command_t* cli_process_io(cli_t* cli) {
     goto cleanup;
   }
 
-  // Handle optional CRC check
-  if (cli->crc_req) {
-    size_t len = strlen(cli->line_buffer);
-    if (len >= 9) {
-      char* space = &cli->line_buffer[len - 9];
-      if (*space == ' ') {
-        uint32_t received_crc;
-        if (cstr_parse_uint32(space + 1, 16, &received_crc)) {
-          uint32_t calculated_crc =
-              ~cli_crc32(CRC32_INITIAL, cli->line_buffer, len - 9);
-          if (calculated_crc == received_crc) {
-            *space = '\0';
-          } else {
-            cli_error(cli, CLI_ERROR_INVALID_CRC, "Expected %08X, got %08X",
-                      calculated_crc, received_crc);
-            goto cleanup;
-          }
-        } else {
-          cli_error(cli, CLI_ERROR_INVALID_CRC, "Invalid CRC format");
-          goto cleanup;
-        }
-      } else {
-        cli_error(cli, CLI_ERROR_INVALID_CRC, "CRC suffix missing");
-        goto cleanup;
-      }
-    } else {
-      cli_error(cli, CLI_ERROR_INVALID_CRC, "Line too short for CRC");
-      goto cleanup;
-    }
-  }
-
   cli_history_add(cli, cli->line_buffer);
 
+  // Calculate CRC of the command line (excluding the expected CRC suffix)
+  // (we may not use the value if crc is not requested)
+  size_t crc_offset = cstr_starts_with(cli->line_buffer, CLI_CRC_PREFIX)
+                          ? strlen(CLI_CRC_PREFIX)
+                          : 0;
+  uint32_t calculated_crc =
+      ~cli_crc32(CRC32_INITIAL, cli->line_buffer + crc_offset,
+                 MAX((int)cli->line_len - (int)crc_offset - CLI_CRC_LENGTH, 0));
+
   // Split command line into arguments
   if (!cli_split_args(cli)) {
     cli_error(cli, CLI_ERROR_FATAL, "Too many arguments.");
@@ -686,6 +674,34 @@ const cli_command_t* cli_process_io(cli_t* cli) {
     goto cleanup;
   }
 
+  if (cli->crc_req) {
+    if (cli->args_count < 1) {
+      cli->crc_req = false;
+      cli_error(cli, CLI_ERROR_INVALID_CRC, "CRC suffix missing");
+      goto cleanup;
+    }
+
+    uint32_t crc = 0;
+
+    const char* crc_str = cli_nth_arg(cli, cli->args_count - 1);
+
+    if (strlen(crc_str) != CLI_CRC_LENGTH ||
+        !cstr_parse_uint32(crc_str, 16, &crc)) {
+      cli->crc_req = false;
+      cli_error(cli, CLI_ERROR_INVALID_CRC, "Invalid CRC format");
+      goto cleanup;
+    }
+
+    if (calculated_crc != crc) {
+      cli->crc_req = false;
+      cli_error(cli, CLI_ERROR_INVALID_CRC, "Expected %08X, got %08X",
+                calculated_crc, crc);
+      goto cleanup;
+    }
+
+    --cli->args_count;
+  }
+
   // Find the command handler
   const cli_command_t* found_cmd = cli_find_command(cli, cli->cmd_name);
 
@@ -728,7 +744,7 @@ static int find_arg(const cli_command_t* cmd, const char* name) {
 
     // Extract argument name
     const char* s = p;
-    while (*p != '\0' && (*p != '>' && *p != ']')) {
+    while (*p != '\0' && *p != '>' && *p != ']') {
       p++;
     }
 
diff --git a/core/embed/rtl/inc/rtl/cli.h b/core/embed/rtl/inc/rtl/cli.h
index 87bc9666..65c6b23f 100644
--- a/core/embed/rtl/inc/rtl/cli.h
+++ b/core/embed/rtl/inc/rtl/cli.h
@@ -145,6 +145,8 @@ struct cli {
   uint32_t response_crc;
   /** CRC was requested for the current command */
   bool crc_req;
+  /** CRC is enabled for all subsequent commands */
+  bool crc_auto;
 };
 
 /** Initializes the command line structure */
diff --git a/core/embed/rtl/inc/rtl/strutils.h b/core/embed/rtl/inc/rtl/strutils.h
index ed4fae3f..05b6a770 100644
--- a/core/embed/rtl/inc/rtl/strutils.h
+++ b/core/embed/rtl/inc/rtl/strutils.h
@@ -67,6 +67,24 @@ const char* cstr_skip_whitespace(const char* str);
  */
 bool cstr_starts_with(const char* str, const char* prefix);
 
+/**
+ * Returns true if the null-terminated C-string ends with the suffix.
+ *
+ * @param str The null-terminated C-string to check
+ * @param suffix The suffix to look for
+ * @return true if the string ends with the suffix, false otherwise
+ */
+bool cstr_ends_with(const char* str, const char* suffix);
+
+/**
+ * Removes the suffix from the null-terminated C-string if it exists.
+ *
+ * @param str The null-terminated C-string to modify
+ * @param suffix The suffix to remove
+ * @return true if the suffix was found and removed, false otherwise
+ */
+bool cstr_remove_suffix(char* str, const char* suffix);
+
 /**
  * Decodes the string as a hexadecimal string and writes the binary data to the
  * destination buffer.
diff --git a/core/embed/rtl/strutils.c b/core/embed/rtl/strutils.c
index 4036c7e3..15c9e798 100644
--- a/core/embed/rtl/strutils.c
+++ b/core/embed/rtl/strutils.c
@@ -58,6 +58,23 @@ bool cstr_starts_with(const char* str, const char* prefix) {
   return strlen(str) >= prefix_len && 0 == strncmp(str, prefix, prefix_len);
 }
 
+bool cstr_ends_with(const char* str, const char* suffix) {
+  size_t str_len = strlen(str);
+  size_t suffix_len = strlen(suffix);
+  if (str_len < suffix_len) {
+    return false;
+  }
+  return 0 == strcmp(str + str_len - suffix_len, suffix);
+}
+
+bool cstr_remove_suffix(char* str, const char* suffix) {
+  if (cstr_ends_with(str, suffix)) {
+    str[strlen(str) - strlen(suffix)] = '\0';
+    return true;
+  }
+  return false;
+}
+
 static inline bool parse_nibble(char c, uint32_t* value) {
   uint8_t nibble = 0;