fix(schema): remove Gemini-incompatible tool metadata fields

Sanitize tool schemas by stripping prefill, enumTitles, $id, and patternProperties to prevent Gemini INVALID_ARGUMENT 400 errors, and add unit and executor-level tests to lock in the behavior.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

internal/runtime/executor/antigravity_executor_buildrequest_test.go

@@ -0,0 +1,159 @@
+package executor
+
+import (
+	"context"
+	"encoding/json"
+	"io"
+	"testing"
+
+	cliproxyauth "github.com/router-for-me/CLIProxyAPI/v6/sdk/cliproxy/auth"
+)
+
+func TestAntigravityBuildRequest_SanitizesGeminiToolSchema(t *testing.T) {
+	body := buildRequestBodyFromPayload(t, "gemini-2.5-pro")
+
+	decl := extractFirstFunctionDeclaration(t, body)
+	if _, ok := decl["parametersJsonSchema"]; ok {
+		t.Fatalf("parametersJsonSchema should be renamed to parameters")
+	}
+
+	params, ok := decl["parameters"].(map[string]any)
+	if !ok {
+		t.Fatalf("parameters missing or invalid type")
+	}
+	assertSchemaSanitizedAndPropertyPreserved(t, params)
+}
+
+func TestAntigravityBuildRequest_SanitizesAntigravityToolSchema(t *testing.T) {
+	body := buildRequestBodyFromPayload(t, "claude-opus-4-6")
+
+	decl := extractFirstFunctionDeclaration(t, body)
+	params, ok := decl["parameters"].(map[string]any)
+	if !ok {
+		t.Fatalf("parameters missing or invalid type")
+	}
+	assertSchemaSanitizedAndPropertyPreserved(t, params)
+}
+
+func buildRequestBodyFromPayload(t *testing.T, modelName string) map[string]any {
+	t.Helper()
+
+	executor := &AntigravityExecutor{}
+	auth := &cliproxyauth.Auth{}
+	payload := []byte(`{
+		"request": {
+			"tools": [
+				{
+					"function_declarations": [
+						{
+							"name": "tool_1",
+							"parametersJsonSchema": {
+								"$schema": "http://json-schema.org/draft-07/schema#",
+								"$id": "root-schema",
+								"type": "object",
+								"properties": {
+									"$id": {"type": "string"},
+									"arg": {
+										"type": "object",
+										"prefill": "hello",
+										"properties": {
+											"mode": {
+												"type": "string",
+												"enum": ["a", "b"],
+												"enumTitles": ["A", "B"]
+											}
+										}
+									}
+								},
+								"patternProperties": {
+									"^x-": {"type": "string"}
+								}
+							}
+						}
+					]
+				}
+			]
+		}
+	}`)
+
+	req, err := executor.buildRequest(context.Background(), auth, "token", modelName, payload, false, "", "https://example.com")
+	if err != nil {
+		t.Fatalf("buildRequest error: %v", err)
+	}
+
+	raw, err := io.ReadAll(req.Body)
+	if err != nil {
+		t.Fatalf("read request body error: %v", err)
+	}
+
+	var body map[string]any
+	if err := json.Unmarshal(raw, &body); err != nil {
+		t.Fatalf("unmarshal request body error: %v, body=%s", err, string(raw))
+	}
+	return body
+}
+
+func extractFirstFunctionDeclaration(t *testing.T, body map[string]any) map[string]any {
+	t.Helper()
+
+	request, ok := body["request"].(map[string]any)
+	if !ok {
+		t.Fatalf("request missing or invalid type")
+	}
+	tools, ok := request["tools"].([]any)
+	if !ok || len(tools) == 0 {
+		t.Fatalf("tools missing or empty")
+	}
+	tool, ok := tools[0].(map[string]any)
+	if !ok {
+		t.Fatalf("first tool invalid type")
+	}
+	decls, ok := tool["function_declarations"].([]any)
+	if !ok || len(decls) == 0 {
+		t.Fatalf("function_declarations missing or empty")
+	}
+	decl, ok := decls[0].(map[string]any)
+	if !ok {
+		t.Fatalf("first function declaration invalid type")
+	}
+	return decl
+}
+
+func assertSchemaSanitizedAndPropertyPreserved(t *testing.T, params map[string]any) {
+	t.Helper()
+
+	if _, ok := params["$id"]; ok {
+		t.Fatalf("root $id should be removed from schema")
+	}
+	if _, ok := params["patternProperties"]; ok {
+		t.Fatalf("patternProperties should be removed from schema")
+	}
+
+	props, ok := params["properties"].(map[string]any)
+	if !ok {
+		t.Fatalf("properties missing or invalid type")
+	}
+	if _, ok := props["$id"]; !ok {
+		t.Fatalf("property named $id should be preserved")
+	}
+
+	arg, ok := props["arg"].(map[string]any)
+	if !ok {
+		t.Fatalf("arg property missing or invalid type")
+	}
+	if _, ok := arg["prefill"]; ok {
+		t.Fatalf("prefill should be removed from nested schema")
+	}
+
+	argProps, ok := arg["properties"].(map[string]any)
+	if !ok {
+		t.Fatalf("arg.properties missing or invalid type")
+	}
+	mode, ok := argProps["mode"].(map[string]any)
+	if !ok {
+		t.Fatalf("mode property missing or invalid type")
+	}
+	if _, ok := mode["enumTitles"]; ok {
+		t.Fatalf("enumTitles should be removed from nested schema")
+	}
+}

internal/util/gemini_schema.go

@@ -428,8 +428,9 @@ func flattenTypeArrays(jsonStr string) string {
 
 func removeUnsupportedKeywords(jsonStr string) string {
 	keywords := append(unsupportedConstraints,
-		"$schema", "$defs", "definitions", "const", "$ref", "additionalProperties",
+		"$schema", "$defs", "definitions", "const", "$ref", "$id", "additionalProperties",
-		"propertyNames", // Gemini doesn't support property name validation
+		"propertyNames", "patternProperties", // Gemini doesn't support these schema keywords
+		"enumTitles", "prefill", // Claude/OpenCode schema metadata fields unsupported by Gemini
 	)
 
 	deletePaths := make([]string, 0)

internal/util/gemini_schema_test.go

@@ -870,6 +870,57 @@ func TestCleanJSONSchemaForAntigravity_BooleanEnumToString(t *testing.T) {
 	}
 }
 
+func TestCleanJSONSchemaForGemini_RemovesGeminiUnsupportedMetadataFields(t *testing.T) {
+	input := `{
+		"$schema": "http://json-schema.org/draft-07/schema#",
+		"$id": "root-schema",
+		"type": "object",
+		"properties": {
+			"payload": {
+				"type": "object",
+				"prefill": "hello",
+				"properties": {
+					"mode": {
+						"type": "string",
+						"enum": ["a", "b"],
+						"enumTitles": ["A", "B"]
+					}
+				},
+				"patternProperties": {
+					"^x-": {"type": "string"}
+				}
+			},
+			"$id": {
+				"type": "string",
+				"description": "property name should not be removed"
+			}
+		}
+	}`
+
+	expected := `{
+		"type": "object",
+		"properties": {
+			"payload": {
+				"type": "object",
+				"properties": {
+					"mode": {
+						"type": "string",
+						"enum": ["a", "b"],
+						"description": "Allowed: a, b"
+					}
+				}
+			},
+			"$id": {
+				"type": "string",
+				"description": "property name should not be removed"
+			}
+		}
+	}`
+
+	result := CleanJSONSchemaForGemini(input)
+	compareJSON(t, expected, result)
+}
+
 func TestRemoveExtensionFields(t *testing.T) {
 	tests := []struct {
 		name     string