fix: make UnwrapExpr tolerant of varying whitespace

Handle expressions like ${{expr}} (no inner spaces) in addition to
the standard ${{ expr }} format.

Author: dangrondahl

internal/policy/expression.go

@@ -70,10 +70,12 @@ func WrapExpr(raw string) string {
 }
 
 // UnwrapExpr strips the ${{ }} wrapper, returning the inner expression.
+// Tolerates varying whitespace inside the delimiters.
 func UnwrapExpr(expr string) string {
-	s := strings.TrimPrefix(expr, "${{ ")
-	s = strings.TrimSuffix(s, " }}")
-	return s
+	s := strings.TrimSpace(expr)
+	s = strings.TrimPrefix(s, "${{")
+	s = strings.TrimSuffix(s, "}}")
+	return strings.TrimSpace(s)
 }
 
 // NegateExpr prefixes a raw (unwrapped) expression with the not operator.

internal/policy/expression_test.go

@@ -83,6 +83,11 @@ func TestUnwrapExpr(t *testing.T) {
 	assert.Equal(t, `flow.name == "prod"`, result)
 }
 
+func TestUnwrapExpr_NoInnerSpaces(t *testing.T) {
+	result := UnwrapExpr(`${{flow.name == "prod"}}`)
+	assert.Equal(t, `flow.name == "prod"`, result)
+}
+
 func TestUnwrapExpr_AlreadyRaw(t *testing.T) {
 	result := UnwrapExpr(`flow.name == "prod"`)
 	assert.Equal(t, `flow.name == "prod"`, result)