fix: address PR review feedback for codegen

- Python: remove unnecessary pass in empty dataclasses with methods
- C#: properly type string|null as string? instead of object
- Go: omit optional fields when nil instead of sending null

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: SteveSandersonMS

dotnet/src/Generated/Rpc.cs

@@ -253,7 +253,7 @@ public class SessionPlanReadResult
 
     /// <summary>The content of plan.md, or null if it does not exist</summary>
     [JsonPropertyName("content")]
-    public object Content { get; set; }
+    public string? Content { get; set; }
 }
 
 internal class ReadRequest

go/rpc/generated_rpc.go

@@ -457,7 +457,9 @@ type FleetRpcApi struct {
 func (a *FleetRpcApi) Start(ctx context.Context, params *SessionFleetStartParams) (*SessionFleetStartResult, error) {
 	req := map[string]interface{}{"sessionId": a.sessionID}
 	if params != nil {
-		req["prompt"] = params.Prompt
+		if params.Prompt != nil {
+			req["prompt"] = *params.Prompt
+		}
 	}
 	raw, err := a.client.Request("session.fleet.start", req)
 	if err != nil {

python/copilot/generated/rpc.py

@@ -565,8 +565,6 @@ def to_dict(self) -> dict:
 
 @dataclass
 class SessionPlanUpdateResult:
-    pass
-
     @staticmethod
     def from_dict(obj: Any) -> 'SessionPlanUpdateResult':
         assert isinstance(obj, dict)
@@ -596,8 +594,6 @@ def to_dict(self) -> dict:
 
 @dataclass
 class SessionPlanDeleteResult:
-    pass
-
     @staticmethod
     def from_dict(obj: Any) -> 'SessionPlanDeleteResult':
         assert isinstance(obj, dict)
@@ -661,8 +657,6 @@ def to_dict(self) -> dict:
 
 @dataclass
 class SessionWorkspaceCreateFileResult:
-    pass
-
     @staticmethod
     def from_dict(obj: Any) -> 'SessionWorkspaceCreateFileResult':
         assert isinstance(obj, dict)

scripts/codegen/csharp.ts

@@ -67,7 +67,8 @@ function schemaTypeToCSharp(schema: JSONSchema7, required: boolean, knownTypes:
     if (schema.anyOf) {
         const nonNull = schema.anyOf.filter((s) => typeof s === "object" && s.type !== "null");
         if (nonNull.length === 1 && typeof nonNull[0] === "object") {
-            return schemaTypeToCSharp(nonNull[0] as JSONSchema7, false, knownTypes) + "?";
+            // Pass required=true to get the base type, then add "?" for nullable
+            return schemaTypeToCSharp(nonNull[0] as JSONSchema7, true, knownTypes) + "?";
         }
     }
     if (schema.$ref) {
@@ -76,6 +77,15 @@ function schemaTypeToCSharp(schema: JSONSchema7, required: boolean, knownTypes:
     }
     const type = schema.type;
     const format = schema.format;
+    // Handle type: ["string", "null"] patterns (nullable string)
+    if (Array.isArray(type)) {
+        const nonNullTypes = type.filter((t) => t !== "null");
+        if (nonNullTypes.length === 1 && nonNullTypes[0] === "string") {
+            if (format === "uuid") return "Guid?";
+            if (format === "date-time") return "DateTimeOffset?";
+            return "string?";
+        }
+    }
     if (type === "string") {
         if (format === "uuid") return required ? "Guid" : "Guid?";
         if (format === "date-time") return required ? "DateTimeOffset" : "DateTimeOffset?";

scripts/codegen/go.ts

@@ -246,6 +246,7 @@ function emitMethod(lines: string[], receiver: string, name: string, method: Rpc
     const resultType = toPascalCase(method.rpcMethod) + "Result";
 
     const paramProps = method.params?.properties || {};
+    const requiredParams = new Set(method.params?.required || []);
     const nonSessionParams = Object.keys(paramProps).filter((k) => k !== "sessionId");
     const hasParams = isSession ? nonSessionParams.length > 0 : Object.keys(paramProps).length > 0;
     const paramsType = hasParams ? toPascalCase(method.rpcMethod) + "Params" : "";
@@ -261,7 +262,16 @@ function emitMethod(lines: string[], receiver: string, name: string, method: Rpc
         if (hasParams) {
             lines.push(`    if params != nil {`);
             for (const pName of nonSessionParams) {
-                lines.push(`        req["${pName}"] = params.${toGoFieldName(pName)}`);
+                const goField = toGoFieldName(pName);
+                const isOptional = !requiredParams.has(pName);
+                if (isOptional) {
+                    // Optional fields are pointers - only add when non-nil and dereference
+                    lines.push(`        if params.${goField} != nil {`);
+                    lines.push(`            req["${pName}"] = *params.${goField}`);
+                    lines.push(`        }`);
+                } else {
+                    lines.push(`        req["${pName}"] = params.${goField}`);
+                }
             }
             lines.push(`    }`);
         }

scripts/codegen/python.ts

@@ -160,6 +160,8 @@ async function generateRpc(schemaPath?: string): Promise<void> {
     typesCode = typesCode.replace(/: Any$/gm, ": Any = None");
     // Fix bare except: to use Exception (required by ruff/pylint)
     typesCode = typesCode.replace(/except:/g, "except Exception:");
+    // Remove unnecessary pass when class has methods (quicktype generates pass for empty schemas)
+    typesCode = typesCode.replace(/^(\s*)pass\n\n(\s*@staticmethod)/gm, "$2");
 
     const lines: string[] = [];
     lines.push(`"""