refactor(context): derive execution_source via model_validator

Move derivation out of with_defaults into a model_validator so it fires
on the plain-constructor path too (e.g. dev/init), and never assign None
for unmapped commands so the field stays absent under
model_dump(exclude_unset=True). with_defaults re-applies it since it
mutates command via setattr after construction.

Addresses Copilot review feedback on PR #132.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: Valentina Bojan

src/uipath/runtime/context.py

@@ -7,7 +7,7 @@
 from pathlib import Path
 from typing import Any, Literal
 
-from pydantic import BaseModel, ConfigDict, Field
+from pydantic import BaseModel, ConfigDict, Field, model_validator
 from uipath.core.errors import UiPathFaultedTriggerError
 from uipath.core.tracing import UiPathTraceManager
 
@@ -23,8 +23,6 @@
 
 logger = logging.getLogger(__name__)
 
-# Maps the executing command to an execution source. Commands that do not run
-# an agent are absent, leaving execution_source unset.
 _EXECUTION_SOURCE_BY_COMMAND: dict[str, str] = {
     "run": "runtime",
     "debug": "playground",
@@ -41,12 +39,7 @@ class UiPathRuntimeContext(BaseModel):
     resume: bool = False
     command: str | None = None
     execution_source: str | None = Field(
-        None,
-        description=(
-            "Execution source derived from the command "
-            "(runtime/playground/eval). Propagated to platform clients so "
-            "downstream calls (e.g. guardrails) can identify the run context."
-        ),
+        None, description="Execution source derived from the command."
     )
     job_id: str | None = None
     conversation_id: str | None = Field(
@@ -113,6 +106,28 @@ class UiPathRuntimeContext(BaseModel):
 
     model_config = ConfigDict(arbitrary_types_allowed=True, extra="allow")
 
+    def _apply_execution_source(self) -> None:
+        """Derive execution_source from the command, if not already set.
+
+        Only assigns a mapped value, so the field stays unset (absent under
+        ``model_dump(exclude_unset=True)``) for unmapped commands, and an
+        explicitly-provided value is never overwritten.
+        """
+        if self.execution_source is None and self.command is not None:
+            source = _EXECUTION_SOURCE_BY_COMMAND.get(self.command)
+            if source is not None:
+                self.execution_source = source
+
+    @model_validator(mode="after")
+    def _derive_execution_source(self) -> "UiPathRuntimeContext":
+        """Derive execution_source on the constructor path (e.g. dev/init).
+
+        ``with_defaults`` mutates ``command`` via ``setattr`` after construction,
+        so it re-applies the derivation itself.
+        """
+        self._apply_execution_source()
+        return self
+
     def get_input(self) -> dict[str, Any] | None:
         """Get parsed input data.
 
@@ -362,9 +377,8 @@ def with_defaults(
         for k, v in kwargs.items():
             setattr(base, k, v)
 
-        # Derive the execution source from the command unless explicitly set.
-        if base.execution_source is None and base.command is not None:
-            base.execution_source = _EXECUTION_SOURCE_BY_COMMAND.get(base.command)
+        # setattr does not re-run the validator, so derive explicitly.
+        base._apply_execution_source()
 
         return base
 

tests/test_context.py

@@ -329,34 +329,45 @@ def test_string_output_wrapped_in_dict() -> None:
         ("eval", "eval"),
     ],
 )
+def test_constructor_derives_execution_source(command: str, expected: str) -> None:
+    """execution_source is derived from the command on the plain constructor path."""
+    ctx = UiPathRuntimeContext(command=command)
+
+    assert ctx.execution_source == expected
+
+
+@pytest.mark.parametrize(
+    "command,expected",
+    [
+        ("run", "runtime"),
+        ("eval", "eval"),
+    ],
+)
 def test_with_defaults_derives_execution_source(
     command: str, expected: str, tmp_path: Path, monkeypatch: pytest.MonkeyPatch
 ) -> None:
-    """execution_source is derived from the command when not provided."""
+    """execution_source is also derived via with_defaults."""
     monkeypatch.chdir(tmp_path)
 
     ctx = UiPathRuntimeContext.with_defaults(command=command)
 
     assert ctx.execution_source == expected
 
 
-def test_with_defaults_execution_source_none_for_unmapped_command(
-    tmp_path: Path, monkeypatch: pytest.MonkeyPatch
-) -> None:
-    """Commands that do not run an agent leave execution_source unset."""
-    monkeypatch.chdir(tmp_path)
+def test_execution_source_unset_for_unmapped_command() -> None:
+    """Commands that do not run an agent leave execution_source unset.
 
-    ctx = UiPathRuntimeContext.with_defaults(command="pack")
+    The field must remain unset (not explicitly None) so it is absent from
+    model_dump(exclude_unset=True).
+    """
+    ctx = UiPathRuntimeContext(command="pack")
 
     assert ctx.execution_source is None
+    assert "execution_source" not in ctx.model_dump(exclude_unset=True)
 
 
-def test_with_defaults_explicit_execution_source_not_overwritten(
-    tmp_path: Path, monkeypatch: pytest.MonkeyPatch
-) -> None:
+def test_explicit_execution_source_not_overwritten() -> None:
     """An explicitly provided execution_source takes precedence over the command."""
-    monkeypatch.chdir(tmp_path)
-
-    ctx = UiPathRuntimeContext.with_defaults(command="run", execution_source="custom")
+    ctx = UiPathRuntimeContext(command="run", execution_source="custom")
 
     assert ctx.execution_source == "custom"