Fix: proceed with evaluation when selector references an unknown entity property

pkg/engine/selectors/selectors.go

@@ -419,15 +419,24 @@ func (s *EntitySelection) Select(se *internalpb.SelectorEntity, userOpts ...Sele
 		// check unknowns /before/ an error. Maybe we should try to special-case the one
 		// error we get from the CEL library in this case and check for the rest?
 		if s.detailHasUnknowns(sel, details) {
-			return false, "", ErrResultUnknown
+			if len(opts.unknownPaths) > 0 {
+				// Explicit unknown paths were set by the caller (via WithUnknownPaths), meaning
+				// the caller is doing a first-pass evaluation with intentionally incomplete data
+				// and expects to retry with more information. Signal this intent.
+				return false, "", ErrResultUnknown
+			}
+			// No explicit unknown paths: the entity simply does not have this property.
+			// Properties are not guaranteed to exist, so proceed with evaluation.
+			return true, "", nil
 		}
 
 		if err != nil {
 			return false, "", fmt.Errorf("failed to evaluate Expression: %w", err)
 		}
 
 		if types.IsUnknown(out) {
-			return false, "", ErrResultUnknown
+			// The property is missing from the entity data; proceed with evaluation.
+			return true, "", nil
 		}
 
 		if out.Type() != cel.BoolType {

pkg/engine/selectors/selectors_test.go

@@ -646,8 +646,8 @@ func TestSelectSelectorEntity(t *testing.T) {
 					"github": map[string]any{"is_fork": true},
 				}),
 			),
-			expectedSelectErr: ErrResultUnknown,
-			selected:          false,
+			// Missing property: entity is selected so evaluation can proceed
+			selected: true,
 		},
 		{
 			name: "Attempt to use a property while having nil properties",
@@ -658,8 +658,8 @@ func TestSelectSelectorEntity(t *testing.T) {
 				},
 			},
 			selectorEntityBld: newTestRepoSelectorEntity(newGithubProviderSelector()),
-			expectedSelectErr: ErrResultUnknown,
-			selected:          false,
+			// Missing property: entity is selected so evaluation can proceed
+			selected: true,
 		},
 		{
 			name: "The selector shortcuts if evaluation is not needed for properties",
@@ -947,7 +947,8 @@ func TestSelectorEntityFillProperties(t *testing.T) {
 						},
 					}}
 			},
-			secondSucceeds: false,
+			// property is missing, entity is selected so evaluation can proceed
+			secondSucceeds: true,
 		},
 	}