Added API guardrails with copy

API has been update to return copies when returning immutable objects to
avoid passing internal references to the user that could then modify
them, breaking the internal state. Even if the copy operation is
obsolete in some cases, it is kept in as a safety should the API
functions be modified which would cause a return reference issue, the
concerned API methods are not to be requested at high frequency either
way so the performance hit is estimated to be minimal, the only API
method that may be queried at a high freqency is fetching live values
which are returned as floats which are immutable and therefore not
concerned

src/dynalab_core/dlunit.py

@@ -11,7 +11,10 @@ from zipfile import ZIP_DEFLATED, ZipFile
 from pydantic import BaseModel, Field
 
 from dynalab_core.errors import DLPakError, DLUnitError
-from dynalab_core.protocols.packets.handshake import SignalDescriptor
+from dynalab_core.protocols.packets.handshake import (
+    JsonSignalDescriptor,
+    SignalDescriptor,
+)
 
 
 log = logging.getLogger(__name__)
@@ -19,8 +22,8 @@ log = logging.getLogger(__name__)
 
 class DeriveManifest(BaseModel):
     unit_uuid: UUID
-    input_signals: list[SignalDescriptor] = Field(default_factory=list)
-    return_signal: SignalDescriptor
+    input_signals: list[JsonSignalDescriptor] = Field(default_factory=list)
+    return_signal: JsonSignalDescriptor
     comments: str = ""
 
 
@@ -42,10 +45,13 @@ class DLUnit:
         return_signal: SignalDescriptor,
     ) -> None:
 
+        json_input_signals = [signal.to_json() for signal in input_signals]
+        json_return_signal = return_signal.to_json()
+
         self._manifest = DeriveManifest(
             unit_uuid=unit_uuid,
-            input_signals=input_signals,
-            return_signal=return_signal,
+            input_signals=json_input_signals,
+            return_signal=json_return_signal,
         )
 
     def read(self, file: str | Path) -> Self: