diff --git a/internal/cmd/evaluator.go b/internal/cmd/evaluator.go
index b936e723..31cf906d 100644
--- a/internal/cmd/evaluator.go
+++ b/internal/cmd/evaluator.go
@@ -284,6 +284,7 @@ func newEvaluatorUploadCmd() *cobra.Command {
 				}
 				re := regexp.MustCompile(`\bdef\s+` + regexp.QuoteMeta(funcName) + `\s*\(`)
 				sourceStr = re.ReplaceAllString(sourceStr, "def "+evalFuncName+"(")
+				sourceStr = stripPythonReturnAnnotation(sourceStr, evalFuncName)
 			case "javascript":
 				sourceStr = extractJSFunction(string(source), funcName)
 				if sourceStr == "" {
@@ -438,6 +439,21 @@ func extractPythonFunction(source string, funcName string) string {
 	return strings.Join(lines[startIdx:endIdx], "\n") + "\n"
 }
 
+// stripPythonReturnAnnotation removes a return-type annotation from the def line of an
+// already-extracted, already-renamed function (e.g. `def perform_eval(run) -> dict | None:`
+// becomes `def perform_eval(run):`).
+//
+// The evaluator service's function finder does not handle PEP 604 union return annotations
+// (e.g. `-> dict | None`): uploading such a function fails with "Code evaluator does not
+// contain function with name perform_eval" even though the function is present. A plain
+// annotation (`-> dict`) or no annotation works. The annotation is irrelevant to execution,
+// so we drop it. Only single-line def signatures are handled (the common case); a multi-line
+// signature is left untouched.
+func stripPythonReturnAnnotation(source, funcName string) string {
+	re := regexp.MustCompile(`(?m)^(def ` + regexp.QuoteMeta(funcName) + `\(.*\))\s*->.*?:(\s*(?:#.*)?)$`)
+	return re.ReplaceAllString(source, "$1:$2")
+}
+
 // detectLanguage returns the API language value and the canonical eval function
 // name based on the file extension.
 func detectLanguage(filename string) (language, evalFuncName string) {
diff --git a/internal/cmd/evaluator_test.go b/internal/cmd/evaluator_test.go
index 49368212..19a47732 100644
--- a/internal/cmd/evaluator_test.go
+++ b/internal/cmd/evaluator_test.go
@@ -117,6 +117,49 @@ func TestExtractPythonFunction_EmptySource(t *testing.T) {
 	}
 }
 
+// ---------- stripPythonReturnAnnotation ----------
+
+func TestStripPythonReturnAnnotation_Union(t *testing.T) {
+	// PEP 604 union return annotation: the evaluator service's function finder
+	// can't handle it, so it must be stripped.
+	source := "def perform_eval(run) -> dict | None:\n    return {\"score\": 1}\n"
+	result := stripPythonReturnAnnotation(source, "perform_eval")
+	if !contains(result, "def perform_eval(run):") {
+		t.Errorf("union return annotation should be stripped, got:\n%s", result)
+	}
+	if contains(result, "->") {
+		t.Error("result should not contain a return annotation")
+	}
+	if !contains(result, `return {"score": 1}`) {
+		t.Error("body should be preserved")
+	}
+}
+
+func TestStripPythonReturnAnnotation_Plain(t *testing.T) {
+	source := "def perform_eval(run) -> dict:\n    return {\"score\": 1}\n"
+	result := stripPythonReturnAnnotation(source, "perform_eval")
+	if !contains(result, "def perform_eval(run):") {
+		t.Errorf("plain return annotation should be stripped, got:\n%s", result)
+	}
+}
+
+func TestStripPythonReturnAnnotation_WithParamsAndComment(t *testing.T) {
+	// params plus a trailing comment after the colon
+	source := "def perform_eval(run, example) -> dict | None:  # noqa\n    return {}\n"
+	result := stripPythonReturnAnnotation(source, "perform_eval")
+	if !contains(result, "def perform_eval(run, example):") {
+		t.Errorf("should strip annotation and keep params, got:\n%s", result)
+	}
+}
+
+func TestStripPythonReturnAnnotation_NoAnnotationUnchanged(t *testing.T) {
+	source := "def perform_eval(run):\n    return {\"score\": 1}\n"
+	result := stripPythonReturnAnnotation(source, "perform_eval")
+	if result != source {
+		t.Errorf("source without an annotation should be unchanged, got:\n%s", result)
+	}
+}
+
 // ---------- extractJSFunction ----------
 
 func TestExtractJSFunction_FunctionDeclaration(t *testing.T) {