Implementation:Facebookresearch Habitat lab AppService init

Knowledge Sources	Habitat-Lab
Domains	Human_in_the_Loop, Software_Architecture
Last Updated	2026-02-15 02:00 GMT

Overview

Concrete dependency injection container for HITL application states, providing access to all framework services without tight coupling, provided by habitat-hitl.

Description

The AppService class aggregates all HITL framework services into a single container passed to each AppState. It provides access to the environment, simulator, GUI input, controllers, episode management, recording, and UI utilities. This decouples application logic from framework internals.

Usage

Created by LabDriver during initialization and passed to the create_app_state_lambda factory. Application states access services through the AppService instance.

Code Reference

Source Location

• Repository: habitat-lab
• File: habitat-hitl/habitat_hitl/app_states/app_service.py
• Lines: L30-77

Signature

class AppService:
    def __init__(
        self,
        *,
        config,
        hitl_config,
        users,
        gui_input,
        remote_client_state,
        gui_drawer,
        text_drawer,
        ui_manager,
        get_anim_fraction,
        env,
        sim,
        compute_action_and_step_env,
        step_recorder,
        get_metrics,
        end_episode,
        set_cursor_style,
        episode_helper,
        client_message_manager,
        gui_agent_controllers,
        all_agent_controllers,
        reconfigure_sim,
    ):
        """
        Dependency injection container for HITL app states.
        All parameters are keyword-only.
        """

Import

from habitat_hitl.app_states.app_service import AppService

I/O Contract

Inputs

Name	Type	Required	Description
config	DictConfig	Yes	Full application config
env	Env	Yes	Habitat environment instance
sim	Simulator	Yes	Habitat simulator instance
gui_input	GuiInput	Yes	User input handler
gui_agent_controllers	List	Yes	Per-agent GUI controllers
all_agent_controllers	List	Yes	All agent controllers (GUI + AI)

Outputs

Name	Type	Description
app_service	AppService	Container with all framework services accessible as attributes

Usage Examples

Access Services in AppState

from habitat_hitl.app_states.app_state_abc import AppState

class MyGameplayState(AppState):
    def __init__(self, app_service: AppService):
        self._app_service = app_service

    def sim_update(self, dt, post_sim_update_dict):
        # Access framework services
        env = self._app_service.env
        sim = self._app_service.sim
        metrics = self._app_service.get_metrics()
        self._app_service.end_episode(do_reset=True)

Related Pages

Implements Principle

• Principle:Facebookresearch_Habitat_lab_App_State_Machine

Requires Environment

• Environment:Facebookresearch_Habitat_lab_HITL_Runtime_Environment