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backend/internal/signature/gpt_validation_test.go

@@ -0,0 +1,35 @@
+package signature
+
+import (
+	"encoding/base64"
+	"strings"
+	"testing"
+)
+
+func testGPTReasoningSignature() string {
+	payload := make([]byte, 1+8+16+16+32)
+	payload[0] = 0x80
+	for i := 9; i < len(payload); i++ {
+		payload[i] = byte(i)
+	}
+	return base64.RawURLEncoding.EncodeToString(payload)
+}
+
+func TestDetectSignatureProvider_GPTReasoning(t *testing.T) {
+	if got := DetectSignatureProvider(testGPTReasoningSignature()); got != SignatureProviderGPT {
+		t.Fatalf("DetectSignatureProvider(GPT) = %q, want %q", got, SignatureProviderGPT)
+	}
+}
+
+func TestInspectGPTReasoningSignatureRejectsUnicodeEllipsis(t *testing.T) {
+	sig := testGPTReasoningSignature()
+	polluted := sig[:20] + string(rune(0x2026)) + sig[20:]
+
+	_, err := InspectGPTReasoningSignature(polluted)
+	if err == nil {
+		t.Fatal("expected invalid GPT reasoning signature")
+	}
+	if !strings.Contains(err.Error(), "non-base64url character U+2026") {
+		t.Fatalf("error = %q, want U+2026 base64url detail", err.Error())
+	}
+}