diff --git a/internal/ai/llm/openai/openai.go b/internal/ai/llm/openai/openai.go
index cdd4265..44828d7 100644
--- a/internal/ai/llm/openai/openai.go
+++ b/internal/ai/llm/openai/openai.go
@@ -90,25 +90,22 @@ func New(cfg Config) (*Provider, error) {
 	if u.User != nil || strings.ContainsAny(cfg.BaseURL, "?#") {
 		return nil, errors.New("openai: base URL must not carry credentials, a query or a fragment")
 	}
-	// An error that names caller-supplied text has the API key redacted from
-	// it before it is quoted.
+	// No error from New quotes caller-supplied text or a name derived from
+	// it: any such text may equal or contain the API key, and redaction
+	// cannot catch a fragment or a case-changed copy of it.
 	switch cfg.StructuredOutput {
 	case JSONSchema, JSONObject, PromptOnly:
 	default:
-		return nil, fmt.Errorf("openai: unknown structured output mode %q", redactKey(string(cfg.StructuredOutput), cfg.APIKey))
+		return nil, errors.New("openai: unknown structured output mode")
 	}
 	headers := make(http.Header, len(cfg.Headers)+1)
 	for name, value := range cfg.Headers {
-		// Caller-supplied names and values are never echoed: either may carry
-		// a credential, and canonicalising a name changes its case, which
-		// defeats redaction. Only a managed name, which is a fixed known
-		// string, is named.
 		if !validHeaderName(name) {
 			return nil, errors.New("openai: an extra header name is not a valid HTTP token")
 		}
 		canonical := textproto.CanonicalMIMEHeaderKey(name)
 		if managedHeaders[canonical] {
-			return nil, fmt.Errorf("openai: extra header %q is set by the adapter", canonical)
+			return nil, errors.New("openai: an extra header is set by the adapter")
 		}
 		if !validHeaderValue(value) {
 			return nil, errors.New("openai: an extra header value has a control character")
diff --git a/internal/ai/llm/openai/openai_test.go b/internal/ai/llm/openai/openai_test.go
index 6feff02..745da45 100644
--- a/internal/ai/llm/openai/openai_test.go
+++ b/internal/ai/llm/openai/openai_test.go
@@ -652,6 +652,38 @@ func TestNewConfigErrorsNeverLeakKey(t *testing.T) {
 	}
 }
 
+// TestNewManagedHeaderErrorNeverLeaksKey uses an API key that is itself a
+// managed header name, so naming the rejected header would print the key.
+func TestNewManagedHeaderErrorNeverLeaksKey(t *testing.T) {
+	for _, key := range []string{"Authorization", "Content-Type", "Host"} {
+		_, err := New(Config{
+			BaseURL:          "https://example.com/v1",
+			APIKey:           key,
+			StructuredOutput: JSONSchema,
+			Headers:          map[string]string{key: "x"},
+		})
+		if err == nil {
+			t.Errorf("key %q: New() = nil error", key)
+			continue
+		}
+		for _, secret := range []string{key, "Bearer " + key} {
+			if strings.Contains(strings.ToLower(err.Error()), strings.ToLower(secret)) {
+				t.Errorf("key %q: error leaks %q: %v", key, secret, err)
+			}
+		}
+	}
+}
+
+// TestNewModeErrorNeverLeaksKeyFragment uses a structured output mode that is
+// a fragment of the API key, which redacting the whole key would not catch.
+func TestNewModeErrorNeverLeaksKeyFragment(t *testing.T) {
+	_, err := New(Config{BaseURL: "https://example.com/v1", APIKey: testKey, StructuredOutput: StructuredOutput(testKey[:20])})
+	if err == nil {
+		t.Fatal("New() = nil error")
+	}
+	assertNoSecret(t, err)
+}
+
 func TestAcceptHeader(t *testing.T) {
 	for name, tc := range map[string]struct {
 		headers map[string]string