Fit all STM32 Companions with checked fractional preferences

Stage STM32 preference prefixes and checked footers in one atomic image, reject declared tails that encounter premature EOF, and share the typed CLI rollback helper. Use the proven Wio Mini code-layout flags on Wio E5 and Tiny Relay without changing features or memory boundaries. All four STM32 targets and RAK4631 Full pass at the full 1.18.0.1 release version length.

test/test_local_cli_access.py

@@ -16,6 +16,7 @@ PREAMBLE = r'''
 #include <cstring>
 #include <cstdint>
 #include <initializer_list>
+#include <string>
 #define TBEAM_SX1262 1
 #include <helpers/CLICommandUtils.h>
 #include <helpers/RadioProfileCommandUtils.h>
@@ -164,6 +165,7 @@ struct MyMesh : CompanionFleetFixture {
   void cancelAllFloodRetries(){}
   void resetContacts(){++resets;}
   bool savePrefs(){++saves;return save_ok;}
+  @SAVE_PREFERENCE@
   int getTotalAirTime(){return 0;}
   int getReceiveAirTime(){return 0;}
   int getNumSentFlood(){return 0;}
@@ -288,6 +290,23 @@ int main() {
     assert(node.handleCommand(command,0,reply));
     assert(!strcmp(reply,"OK") && board.power_offs==previous+1);
   }
+  // Exercise the real timezone dispatch and typed transaction helper, not a
+  // fixture-only setter: a failed save must preserve the exact fraction.
+  node.save_ok=true;
+  assert(node.handleCommand("set tz.offset 5.75",0,reply) && !strcmp(reply,"OK"));
+  assert(node._prefs.tz_offset==5.75f);
+  assert(node.handleCommand("get tz.offset",0,reply) && !strcmp(reply,"> 5.75"));
+  node.save_ok=false;
+  const int timezone_saves=node.saves;
+  assert(node.handleCommand("set tz.offset -3.5",0,reply));
+  assert(strstr(reply,"Error") && node.saves==timezone_saves+1);
+  assert(node._prefs.tz_offset==5.75f);
+  for(const char* bad:{"nan","inf","5.75junk","15","-12.25"}) {
+    const std::string command=std::string("set tz.offset ")+bad;
+    assert(node.handleCommand(command.c_str(),0,reply));
+    assert(strstr(reply,"Error") && node.saves==timezone_saves+1);
+    assert(node._prefs.tz_offset==5.75f);
+  }
 }
 '''
 
@@ -405,6 +424,9 @@ int main() {
             "void MyMesh::onContactCacheFlushed()",
             "bool MyMesh::handleDirectCommand(", "bool MyMesh::handleCommand(",
             "void MyMesh::onCLICommandRecv("))
+        header = (ROOT / "examples/companion_radio/MyMesh.h").read_text()
+        preamble = PREAMBLE.replace("@SAVE_PREFERENCE@", extract_braced(
+            header, "template <typename T> bool savePreference("))
         for export, webconfig in ((0, False), (1, False), (0, True), (1, True)):
             with self.subTest(export=export, webconfig=webconfig), tempfile.TemporaryDirectory() as temp:
                 binary = Path(temp) / "test"
@@ -415,7 +437,7 @@ int main() {
                     "-DMESH_ENABLE_LOST_REPLY=1",
                     *(["-DWITH_WEBCONFIG=1"] if webconfig else []),
                     *SANITIZER_FLAGS, "-o", str(binary),
-                ], input=PREAMBLE+implementation+SCENARIOS, text=True, capture_output=True)
+                ], input=preamble+implementation+SCENARIOS, text=True, capture_output=True)
                 self.assertEqual(result.returncode, 0, result.stderr)
                 result = subprocess.run([str(binary)], capture_output=True, text=True)
                 self.assertEqual(result.returncode, 0, result.stdout+result.stderr)