How We Are Cutting SDK Development Time from Months to Days with AccelByte CodeGen and AI

You are helping me extend our AccelByte CodeGen system to support a new game engine by creating a reusable SDK template pack and a thin engine-specific runtime layer.

Context (architecture and tooling):

- The project is a Jinja2-based code generator described in `CLAUDE.md` at the repo root, with template authoring details in `templates/CLAUDE.md`.
- It reads OpenAPI specs for our backend services and renders templates using an OpenAPI processor/renderer stack plus a set of Jinja2 extensions and filters.
- Each SDK “template pack” lives under `templates/<name>/` and typically contains:
  - `config.yaml` (render config: processor, renderer, extensions, loaders)
  - `macros.j2` (shared Jinja macros)
  - `version.txt`, `README.md`
  - `sdk/` or `templates/` subfolders with per-model, per-operation, and per-wrapper templates.
- We already have mature packs for several non-engine targets (e.g., Unreal, Unity, Go, Python, C#, Java, etc.).
- Now we want to add new **engine-focused packs** (such as Godot/GDScript or Roblox/Luau) that follow the same architectural principles:
  - For a Godot/GDScript-style engine, we want per-service scripts that call a shared HTTP client object and return a dictionary-like result (for example, a map with a `success` flag and response data).
  - For a Roblox/Luau-style engine, we want per-operation modules that call an injected `httpClient:request(...)` and return a `(boolean, ResultType?)` pair, plus tag-based wrapper classes that delegate to those operations.

Goal (what you should design):

For a new engine (or language) target, help me design the **core templates and macros** that:

1. **Turn OpenAPI operations into engine-friendly functions/methods**
   - For each operation, generate a function/method whose:
     - Name is derived from `operationId` using language-appropriate casing rules.
     - Parameters come from OpenAPI path, query, body, and form fields, with:
       - Required vs optional handled explicitly in the signature.
       - Appropriate type hints (or doc comments) based on our FieldType enums.
       - Reasonable defaults for optional parameters (e.g., sentinel values for numerics in GDScript, optional types in Luau).
   - Inside the function:
     - Build the URL path from the template (e.g. `"/users/{userId}"`) and substitute path parameters with properly encoded values.
       - In Godot, we build `url_path` as a `String` and call `.replace(...)` and `uri_encode()` on values.
       - In Roblox, we use a backtick string and `config` + `params` interpolation via a helper macro like `luau_path(...)`.
     - Optionally build a query string from query params:
       - Only include provided values.
       - Apply URL encoding (e.g. `HttpService:UrlEncode` in Luau; `AccelbyteHttp.build_query_string` in GDScript).
     - Optionally build a request body:
       - JSON (e.g. `JSON.stringify(body)` in GDScript; `body` table in Luau).
       - `application/x-www-form-urlencoded` (e.g. form dictionary → encoded string).
     - Choose auth behavior based on operation security:
       - Basic auth vs bearer tokens vs no auth.
       - The function should not own credentials; it should either:
         - Use an injected token/basicauth provider (Luau), or
         - Use an injected HTTP client plus an `_auth_token` field and/or client ID (GDScript).
     - Make a single call into an injected HTTP client / transport abstraction, for example:
       - Godot: `await _http.request(url, AccelbyteHttp.Method.<VERB>, headers, request_body)` returning a `Dictionary`.
       - Roblox: `return httpClient:request(method, url, tokenOrNil, bodyOrNil, contentTypeOrNil)` returning `(boolean, ResultType?)`.
     - Match the existing pattern for the chosen engine:
       - For Godot-style targets, return a `Dictionary` with `success` and payload fields that callers will inspect.
       - For Roblox-style targets, return a `(boolean, data?)` pair where `boolean` indicates HTTP/transport success.

2. **Generate a thin wrapper/facade per service/tag**
   - For engines like Godot:
     - Generate one service class per spec (`*_service.gd`) with:
       - Engine-native fields (base URL, service URL, namespace, auth token, client ID).
       - Setter methods called by a higher-level SDK (`set_base_url`, `set_namespace`, `set_auth_token`, `set_client_id`, etc.).
       - One method per operation, implemented using the per-operation logic described above and calling the shared HTTP client.
   - For engines like Roblox:
     - Generate a wrapper type per tag that:
       - Stores references to the engine’s HTTP client, token repository, and SDK config.
       - Exposes one method per operation, with a typed `params` table.
       - Internally delegates to a generated per-operation function module:
         `return _OperationName(self._http, self._tokens, self._config, params)`.

3. **Share as much logic as possible via macros**
   - Put reusable logic in `macros.j2`, including:
     - Mapping our FieldType/container types to engine types (e.g., `int`/`float`/`String`/`Dictionary` in GDScript, Luau type aliases for models, etc.).
     - Building path strings with substituted parameters (`namespace` taken from config where appropriate).
     - Building query strings from param lists (with optional vs required behavior).
     - Building form bodies from `form_data_params`.
     - Emitting a shared parameter annotation/signature block so both per-operation templates and wrappers can reuse the same param shape.

4. **Clean separation between generated code and engine runtime**
   - Assume a small, hand-written engine runtime will exist that provides:
     - An HTTP client abstraction (AccelbyteHttp in Godot, httpClient in Roblox) with a stable request API.
     - A token provider or token repository (`tokenProvider`/`_tokens`) that exposes operations like `getAccessToken()` and stores expiry metadata.
     - A config object for base URLs, namespaces, and engine-specific settings.
   - Generated code must:
     - Not hardcode credentials.
     - Use only these injected abstractions to access network and auth.
     - Be safe to regenerate from specs without overwriting engine-specific logic.

5. **Documentation and comments**
   - At the top of each generated file, include:
     - A “DO NOT EDIT – generated from OpenAPI spec” notice.
     - A short, engine-appropriate usage example:
       - Godot: `var service = sdk.get_service(MyService); var result = await service.my_method(...)`.
       - Roblox: `local ok, result = MyTag:MyOperation({ ... })`.
   - Keep comments focused on non-obvious behavior (e.g., how auth is inferred from OpenAPI security, how numeric sentinel defaults work in GDScript, or how config-injected `namespace` behaves in Luau).

What to produce in your answer:

1. A proposed `macros.j2` skeleton for this new engine target, modeled on what we already do for GDScript and Luau:
   - Type mapping macro(s).
   - Path/query/body builders.
   - A shared parameter annotation macro.
2. A per-operation template that shows:
   - The full function signature (with param types/defaults).
   - URL/query/body construction.
   - The final HTTP client call, returning either a `Dictionary` (Godot-style) or `(boolean, ResultType?)` (Roblox-style), depending on the engine you’re targeting.
3. A per-service or per-tag wrapper template that:
   - Defines the wrapper/service type.
   - Wires in the engine’s HTTP client, token store, and config.
   - Exposes one method per operation that simply delegates to the generated operation logic

{# godot-custom-sdk/templates/service/service.gd.j2 #}

{% for op in operations %}
{% if op.type_ in ['get', 'post', 'put', 'patch', 'delete'] %}
{%- set method_name_raw = op.name | to_snake -%}
{%- ... name normalization and param classification ... -%}

## {{ (op.summary | default(op.name, true) | truncate(70)) }}
## {{ op.type_ | upper }} {{ op.path }}
func {{ method_name }}(
{%- if total_params > 0 %}
{{ param_lines | join("\n") }}
{%- endif %}
) -> Dictionary:
 # Build URL path
 var url_path: String = "{{ op.path }}"
 ...
 # Replace path params with encoded values
 ...
{%- if query_params | length > 0 %}
 # Build query parameters
 var query_params: Dictionary = {}
 ...
 if not query_params.is_empty():
  url_path += "?" + AccelbyteHttp.build_query_string(query_params)
{%- endif %}
 var url: String = _service_url + url_path

{%- if has_form and is_form_urlencoded %}
 # Build form body
 var form_data: Dictionary = {}
 ...
 var request_body: String = AccelbyteHttp.build_form_body(form_data)

 # Build headers (basic vs bearer)
 ...
{%- else %}
 {%- if has_body %}
 var request_body: String = JSON.stringify(body)
 {%- else %}
 var request_body: String = ""
 {%- endif %}
 var headers: PackedStringArray = AccelbyteHttp.get_bearer_headers(_auth_token)
{%- endif %}

{%- if _grant == 'True' %}
 var _result: Dictionary = await _http.request(url, AccelbyteHttp.Method.{{ op.type_ | upper }}, headers, request_body)
 ...
 return _result
{%- elif _revoke == 'True' %}
 var _result: Dictionary = await _http.request(url, AccelbyteHttp.Method.{{ op.type_ | upper }}, headers, request_body)
 ...
 return _result
{%- else %}
 return await _http.request(url, AccelbyteHttp.Method.{{ op.type_ | upper }}, headers, request_body)
{%- endif %}
{% endif %}
{% endfor %}

{# roblox-sdk/sdk/operation.j2 #}

local function {{ name | luau_var }}(httpClient, tokenProvider, config, params: {
{{- macs.luau_params_annotation(path_params, query_params, body_params, form_data_params) }}
}): (boolean, {{ macs.luau_return_type(first_success_response) }}?)
{%- if query_params %}
{{ macs.luau_query_string(query_params) }}
{%- endif %}
{%- if form_data_params %}
{{ macs.luau_form_body(form_data_params) }}
{%- endif %}
{%- if body_params %}
    local body = params.{{ body_params[0].name | luau_var }}
{%- endif %}

    return httpClient:request(
        "{{ type_ | upper }}",
        {{ macs.luau_path(url, path_params) }}{% if query_params %} .. query{% endif %},
{% if has_security_scheme("basic") %}
        nil
{% else %}
        tokenProvider:getAccessToken()
{% endif %}
{%- if form_data_params %},
        formBody,
        "application/x-www-form-urlencoded"
{%- elif body_params %},
        body
{%- endif %}

    )
end

return {{ name | luau_var }}