Home assistant compatibility

[ewowi]

Hookup the lightscontrol module to MQTT so home assistant can control MoonLight devices.

@coderabbitai, make an analysis of the Mqtt functionality already available in the repository and make a proposal how to use that to control the controls in the lightscontrol module

[coderabbitai]

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• Example 2

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Coding Plan

Approach

Ticket Summary

Integrate the ModuleLightsControl module with MQTT to enable Home Assistant control of MoonLight devices through MQTT discovery, including state publishing, command handling, and availability status.

Observations

Codebase Summary

The project is an ESP32-based lighting controller (MoonLight) built on the ESP32-SvelteKit framework. The framework provides comprehensive MQTT support through MqttEndpoint (a template class for stateful service integration), MqttSettingsService (connection lifecycle management), and established patterns for JSON serialization, message throttling, and topic placeholder substitution. The ModuleLightsControl class extends Module (which extends StatefulService<ModuleState>), providing light controls including on/off, brightness (0-255), and RGB color values. The existing MQTT infrastructure already handles connection events, LWT messages for availability, and automatic state synchronization with configurable throttling.

Assumptions

Assumption 1: JSON Schema Selection for Home Assistant Light Discovery

Options Considered:

• Basic schema with separate topics for state/brightness/RGB (simpler but more topics)
• JSON schema with compound payloads containing state, brightness, and color in a single message (more efficient, single topic pair)

Chosen Option: JSON schema with compound payloads containing state, brightness, and color in a single message (more efficient, single topic pair)

Rationale: This aligns with the framework's existing JSON-first approach using ArduinoJson throughout, minimizes MQTT topics, and provides a cleaner state synchronization model. The transformation logic will map between ModuleLightsControl state and Home Assistant's JSON light format.

Assumption 2: Discovery Publishing Timing

Options Considered:

• Publish discovery on every MQTT reconnection (ensures HA always has latest config)
• Publish once on device startup only (reduces network traffic)

Chosen Option: Publish discovery on every MQTT reconnection (ensures HA always has latest config)

Rationale: This ensures Home Assistant receives the discovery configuration even if it restarts or the MQTT broker restarts, and aligns with Home Assistant's recommendation for robust discovery. The small overhead is acceptable given the infrequent nature of reconnections.

💡 User Tips

Regenerate the plan with different choices with @coderabbitai <feedback>.

Implementation Steps

Phase 1: JSON State Transformation Layer

Create transformation functions that convert between ModuleLightsControl state and Home Assistant's JSON light schema format.

Create Home Assistant Light State Transformer

Implement utility functions to serialize and deserialize light state between module format and Home Assistant JSON schema.

• Create new file src/MoonLight/HomeAssistantLight.h with namespace HomeAssistantLight containing transformation utilities
• Implement JsonStateReader function that transforms ModuleLightsControl state to HA format: {state: "ON"/"OFF", brightness: 0-255, color: {r: 0-255, g: 0-255, b: 0-255}, color_mode: "rgb"}
• Implement JsonStateUpdater function that parses HA command JSON and updates ModuleLightsControl state properties (lightsOn, brightness, red, green, blue)
• Handle partial updates (commands may contain only changed properties like brightness or color)
• Map state field ("ON"/"OFF") to lightsOn boolean
• Map color.r, color.g, color.b to module RGB values
• Set color_mode: "rgb" in state messages to indicate RGB support

🤖 Prompt for AI agents

Create Home Assistant JSON light transformation layer for ModuleLightsControl
state conversion.

Create `src/MoonLight/HomeAssistantLight.h` with namespace `HomeAssistantLight`:
- Implement `JsonStateReader` function to serialize ModuleLightsControl state to
HA JSON format with fields: state ("ON"/"OFF"), brightness (0-255), color object
(r, g, b), and color_mode ("rgb")
- Implement `JsonStateUpdater` function to parse HA command JSON and update
ModuleLightsControl state (lightsOn, brightness, red, green, blue)
- Support partial updates where commands may contain only changed properties
- Map state field to lightsOn boolean and color.r/g/b to module RGB values

Phase 2: MQTT Endpoint Integration for State Synchronization

Wire ModuleLightsControl to MQTT using the existing MqttEndpoint template with custom transformation functions.

Task 1: Create MQTT Endpoint Instance in ModuleLightsControl

Instantiate MqttEndpoint to handle bidirectional state synchronization between module and Home Assistant.

• Add MqttEndpoint<ModuleState>* member variable _mqttEndpoint to ModuleLightsControl class
• In ModuleLightsControl initialization (after MQTT settings service is available), create endpoint instance
• Pass HomeAssistantLight transformer functions as JsonStateReader and JsonStateUpdater callbacks
• Configure state topic as homeassistant/light/moonlight_#{unique_id}/state (using framework's placeholder substitution)
• Configure command topic as homeassistant/light/moonlight_#{unique_id}/set
• Use default QoS and retain settings from MQTT service configuration
• The endpoint will automatically publish state changes and subscribe to commands using the existing MqttEndpoint throttling and connection management

Task 2: Handle Endpoint Lifecycle

Ensure proper initialization and cleanup of the MQTT endpoint throughout module lifetime.

• Initialize endpoint in ModuleLightsControl's begin() or setup method after MQTT client is available
• Pass reference to MQTT client from framework's _mqttSettingsService->getMqttClient()
• Endpoint will automatically register connection callbacks and manage subscriptions
• Leverage existing MqttEndpoint cleanup in destructor (no additional cleanup needed)

🤖 Prompt for AI agents

Wire ModuleLightsControl to MQTT using MqttEndpoint for bidirectional state
synchronization.

In ModuleLightsControl class:
- Add `MqttEndpoint<ModuleState>*` member variable `_mqttEndpoint`
- In initialization (begin/setup method), create MqttEndpoint instance with
HomeAssistantLight transformer functions as callbacks
- Configure state topic: `homeassistant/light/moonlight_#{unique_id}/state`
- Configure command topic: `homeassistant/light/moonlight_#{unique_id}/set`
- Pass MQTT client reference from `_mqttSettingsService->getMqttClient()`
- Use default QoS and retain settings from MQTT service
- Rely on MqttEndpoint's automatic connection handling, subscriptions, and
cleanup

Phase 3: Home Assistant Discovery Configuration

Implement discovery message publishing to enable automatic device detection in Home Assistant.

Task 1: Create Discovery Message Builder

Build the JSON discovery configuration payload according to Home Assistant's MQTT light specification.

• Add method buildDiscoveryConfig() in HomeAssistantLight namespace that returns JsonDocument
• Include required fields: name (e.g., "MoonLight"), unique_id (using framework's getUniqueId()), schema: "json"
• Specify topics: state_topic, command_topic (matching Phase 2 topics), availability_topic (using framework's will topic from MqttSettingsService)
• Declare supported_color_modes: ["rgb"] and brightness: true to enable full feature set
• Add device metadata block: device: {identifiers: ["moonlight_#{unique_id}"], name: "MoonLight", model: "MoonLight Controller", manufacturer: "#{platform}"}
• Set optimistic: false since state_topic is provided
• Use placeholder substitution via SettingValue::format() for unique_id and platform values

Task 2: Implement Discovery Publisher

Create a component that publishes discovery configuration when MQTT connects.

• Add HomeAssistantDiscoveryPublisher class or static function that manages discovery publishing
• Register callback on MQTT client's onConnect() event (multiple handlers supported by PsychicMqttClient)
• In callback, publish discovery JSON to homeassistant/light/moonlight_#{unique_id}/config with QoS 1 and retain flag set to true
• Use serializeJson() to convert discovery JsonDocument to string payload
• Access MQTT client via framework's MqttSettingsService
• Ensure discovery publishes after MqttEndpoint has subscribed (connection callbacks are processed sequentially)

Task 3: Integrate Discovery Publisher with ModuleLightsControl

Wire the discovery publisher into module initialization alongside the MQTT endpoint.

• Instantiate or invoke discovery publisher setup in ModuleLightsControl initialization
• Pass MQTT client reference and ensure publisher registers its connection callback
• Discovery will automatically publish on every MQTT connection/reconnection
• No additional state management needed (discovery is fire-and-forget)

🤖 Prompt for AI agents

Implement Home Assistant MQTT discovery for automatic device detection.

In HomeAssistantLight namespace:
- Add `buildDiscoveryConfig()` method returning JsonDocument with HA MQTT light
discovery payload
- Include fields: name, unique_id, schema ("json"), state_topic, command_topic,
availability_topic, supported_color_modes (["rgb"]), brightness (true),
optimistic (false)
- Add device metadata: identifiers, name, model, manufacturer
- Use `SettingValue::format()` for placeholder substitution

Create `HomeAssistantDiscoveryPublisher` component:
- Register onConnect callback on MQTT client
- In callback, publish discovery JSON to
`homeassistant/light/moonlight_#{unique_id}/config` with QoS 1 and retain=true
- Use `serializeJson()` for payload conversion

In ModuleLightsControl initialization:
- Instantiate/setup discovery publisher with MQTT client reference
- Publisher automatically handles republishing on reconnection

Phase 4: Configuration and Testing Support

Ensure MQTT topics use proper identifiers and provide configuration for testing.

Task 1: Configure Topic Naming with Unique Identifiers

Ensure all MQTT topics use the framework's placeholder substitution for device identification.

• Verify topics use #{unique_id} placeholder: homeassistant/light/moonlight_#{unique_id}/state, /set, /config
• Topics will be formatted via SettingValue::format() at runtime to replace placeholders
• Unique ID derives from last 2 bytes of MAC address (already implemented in framework)
• Availability topic references framework's _retainedWillTopic from MqttSettingsService (publishes "online"/"offline")

Task 2: Add Integration Documentation

Document the Home Assistant MQTT integration for developers and users.

• Create or update documentation file (e.g., docs/integrations/homeassistant.md)
• Explain discovery process, topic structure, and available controls (on/off, brightness, RGB color)
• Note that availability status uses framework's LWT mechanism
• Include example Home Assistant automation/configuration snippets if helpful
• Document supported color modes and brightness range

🤖 Prompt for AI agents

Finalize MQTT topic configuration and add documentation.

Verify topic naming:
- Confirm all topics use `#{unique_id}` placeholder: state, set, config, and
availability topics
- Ensure topics formatted via `SettingValue::format()` at runtime
- Verify availability topic references framework's `_retainedWillTopic`

Create documentation:
- Add/update `docs/integrations/homeassistant.md`
- Document discovery process, topic structure, and controls (on/off, brightness,
RGB)
- Explain availability status via LWT mechanism
- Include example automations and supported features

---

🚀 Next Steps

🤖 All AI agent prompts combined

Task: 1

Create Home Assistant JSON light transformation layer for ModuleLightsControl
state conversion.

Create `src/MoonLight/HomeAssistantLight.h` with namespace `HomeAssistantLight`:
- Implement `JsonStateReader` function to serialize ModuleLightsControl state to
HA JSON format with fields: state ("ON"/"OFF"), brightness (0-255), color object
(r, g, b), and color_mode ("rgb")
- Implement `JsonStateUpdater` function to parse HA command JSON and update
ModuleLightsControl state (lightsOn, brightness, red, green, blue)
- Support partial updates where commands may contain only changed properties
- Map state field to lightsOn boolean and color.r/g/b to module RGB values
===============================================================================

Task: 2

Wire ModuleLightsControl to MQTT using MqttEndpoint for bidirectional state
synchronization.

In ModuleLightsControl class:
- Add `MqttEndpoint<ModuleState>*` member variable `_mqttEndpoint`
- In initialization (begin/setup method), create MqttEndpoint instance with
HomeAssistantLight transformer functions as callbacks
- Configure state topic: `homeassistant/light/moonlight_#{unique_id}/state`
- Configure command topic: `homeassistant/light/moonlight_#{unique_id}/set`
- Pass MQTT client reference from `_mqttSettingsService->getMqttClient()`
- Use default QoS and retain settings from MQTT service
- Rely on MqttEndpoint's automatic connection handling, subscriptions, and
cleanup
===============================================================================

Task: 3

Implement Home Assistant MQTT discovery for automatic device detection.

In HomeAssistantLight namespace:
- Add `buildDiscoveryConfig()` method returning JsonDocument with HA MQTT light
discovery payload
- Include fields: name, unique_id, schema ("json"), state_topic, command_topic,
availability_topic, supported_color_modes (["rgb"]), brightness (true),
optimistic (false)
- Add device metadata: identifiers, name, model, manufacturer
- Use `SettingValue::format()` for placeholder substitution

Create `HomeAssistantDiscoveryPublisher` component:
- Register onConnect callback on MQTT client
- In callback, publish discovery JSON to
`homeassistant/light/moonlight_#{unique_id}/config` with QoS 1 and retain=true
- Use `serializeJson()` for payload conversion

In ModuleLightsControl initialization:
- Instantiate/setup discovery publisher with MQTT client reference
- Publisher automatically handles republishing on reconnection
===============================================================================

Task: 4

Finalize MQTT topic configuration and add documentation.

Verify topic naming:
- Confirm all topics use `#{unique_id}` placeholder: state, set, config, and
availability topics
- Ensure topics formatted via `SettingValue::format()` at runtime
- Verify availability topic references framework's `_retainedWillTopic`

Create documentation:
- Add/update `docs/integrations/homeassistant.md`
- Document discovery process, topic structure, and controls (on/off, brightness,
RGB)
- Explain availability status via LWT mechanism
- Include example automations and supported features

💡 Iterate on the plan with: @coderabbitai <feedback>

Example Feedback
- @coderabbitai You can skip phase 3. Add a simple unit test case for phase 2.
- @coderabbitai For assumption 1 go ahead with option 3 and replan.

---

💬 Have feedback or questions? Drop into our discord!

[ewowi]

@coderabbitai, can you provide the minimal code snippets for a 'hello world' to control the on/off and the brightness slider via HA

[coderabbitai]

🧩 Analysis chain

🏁 Script executed:

#!/bin/bash
# Find ModuleLightsControl class definition
fd -e h -e cpp "ModuleLightsControl" --exec cat {}

Length of output: 16974

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#!/bin/bash
# Find examples of MqttEndpoint usage in the codebase
rg -n "MqttEndpoint" -A 5 -B 2 --type cpp

Length of output: 3562

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#!/bin/bash
# Look for Module class and ModuleState structure
rg -n "class Module\b" -A 10 --type cpp

Length of output: 752

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#!/bin/bash
# Check for existing MQTT service integration patterns
rg -n "MqttSettingsService" -A 3 --type cpp | head -50

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#!/bin/bash
# Check for getMqttClient method and usage patterns
rg -n "getMqttClient" -A 2 -B 2 --type cpp

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#!/bin/bash
# Look for StatefulService structure to understand the state pattern
rg -n "class StatefulService" -A 15 --type cpp | head -50

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#!/bin/bash
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rg -n "class ModuleState\b" -A 20 --type cpp

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#!/bin/bash
# Check for SettingValue::format usage for placeholder substitution
rg -n "SettingValue::format" -A 2 -B 2 --type cpp

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@ewowi, here are minimal "hello world" code snippets to control on/off and brightness via Home Assistant:

1. Create Transformation Functions

Add this new file src/MoonLight/HomeAssistantLight.h:

#ifndef HomeAssistantLight_h
#define HomeAssistantLight_h

#include <ArduinoJson.h>
#include "Module.h"

namespace HomeAssistantLight {

// Convert ModuleLightsControl state -> Home Assistant JSON
void stateToJson(JsonObject& root, ModuleState& state) {
  root["state"] = state.data["lightsOn"].as<bool>() ? "ON" : "OFF";
  root["brightness"] = state.data["brightness"].as<uint8_t>();
}

// Convert Home Assistant JSON -> ModuleLightsControl state updates
void jsonToState(JsonObject& root, ModuleState& state) {
  if (root.containsKey("state")) {
    state.data["lightsOn"] = (root["state"] == "ON");
  }
  if (root.containsKey("brightness")) {
    state.data["brightness"] = root["brightness"].as<uint8_t>();
  }
}

}  // namespace HomeAssistantLight

#endif

2. Add MQTT Endpoint to ModuleLightsControl

In ModuleLightsControl.h, add these changes:

#include "HomeAssistantLight.h"
#include "MqttEndpoint.h"

class ModuleLightsControl : public Module {
 private:
  MqttEndpoint<ModuleState>* _mqttEndpoint = nullptr;
  
 public:
  // ... existing code ...
  
  void begin() override {
    Module::begin();
    // ... existing begin() code ...
    
    // Setup MQTT endpoint for Home Assistant
    PsychicMqttClient* mqttClient = _sveltekit->getMqttClient();
    if (mqttClient) {
      _mqttEndpoint = new MqttEndpoint<ModuleState>(
        HomeAssistantLight::stateToJson,      // state -> JSON
        HomeAssistantLight::jsonToState,      // JSON -> state
        this,                                  // StatefulService
        mqttClient,
        "homeassistant/light/moonlight_#{unique_id}/state",  // publish topic
        "homeassistant/light/moonlight_#{unique_id}/set"     // subscribe topic
      );
      
      // Publish discovery config on MQTT connect
      mqttClient->onConnect([this, mqttClient]() {
        publishDiscovery(mqttClient);
      });
    }
  }
  
  void publishDiscovery(PsychicMqttClient* mqttClient) {
    JsonDocument doc;
    JsonObject config = doc.to<JsonObject>();
    
    config["name"] = "MoonLight";
    config["unique_id"] = SettingValue::format("moonlight_#{unique_id}");
    config["schema"] = "json";
    config["brightness"] = true;
    config["state_topic"] = SettingValue::format("homeassistant/light/moonlight_#{unique_id}/state");
    config["command_topic"] = SettingValue::format("homeassistant/light/moonlight_#{unique_id}/set");
    
    String payload;
    serializeJson(config, payload);
    
    String topic = SettingValue::format("homeassistant/light/moonlight_#{unique_id}/config");
    mqttClient->publish(topic.c_str(), 1, true, payload.c_str());
    
    EXT_LOGI(ML_TAG, "Published HA discovery to %s", topic.c_str());
  }
};

3. How It Works

State Publishing: When you change lightsOn or brightness via the web UI or button, MqttEndpoint automatically publishes to the state topic in HA format:

{"state": "ON", "brightness": 128}

Command Handling: When Home Assistant sends a command to the set topic, MqttEndpoint receives it and updates your ModuleLightsControl state, triggering onUpdate() automatically.

Discovery: On MQTT connection, Home Assistant automatically discovers the light entity and shows controls for on/off and brightness.

Testing

1. Ensure MQTT is configured in your MoonLight device
2. Flash the updated code
3. Check Home Assistant - a new "MoonLight" light entity should appear automatically
4. Toggle and adjust brightness - it should sync bidirectionally!

The MqttEndpoint handles all the connection management, throttling, and state synchronization automatically using the framework's existing infrastructure.

---

🧠 Learnings used

Learnt from: CR
Repo: MoonModules/MoonLight PR: 0
File: misc/parking/GEMINI.md:0-0
Timestamp: 2025-11-29T16:17:30.619Z
Learning: Applies to misc/parking/src/**/*.{h,cpp} : Extend core functionality by implementing custom services in C++ that integrate with MQTT, the web interface, and device logic (e.g., LightMqttSettingsService, LightStateService)

[ewowi]

@coderabbitai, can you comment on this:

Spannend. Gaat het werken? In mijn ervaring moet je tig iteraties doorlopen om iets wat AI suggereert echt werkt.

Overigens was mijn doel aansluiten op de HomeBridge MQTT plugin, zodat het met Apple Homekit werkt. Home Assistent heb ik wel draaien, maar gebruik ik niet actief.

[coderabbitai]

@ewowi, je hebt helemaal gelijk - AI-suggesties hebben vaak meerdere iteraties nodig voordat ze echt werken in jouw specifieke setup! Ik waardeer je realistische verwachting.

En ah, dat is een belangrijk verschil! HomeBridge MQTT voor Apple HomeKit werkt heel anders dan Home Assistant MQTT discovery. Er zijn twee populaire HomeBridge MQTT plugins met verschillende aanpakken:

1. homebridge-mqttthing (meest populair)

Gebruikt setXXX topics voor commands en getXXX topics voor state updates. Voor een lightbulb met brightness zou je bijvoorbeeld hebben:

• setOn: voor aan/uit commando's (payload: true/false)
• getOn: voor state updates van jouw device
• setBrightness: voor brightness commando's (payload: 0-100)
• getBrightness: voor brightness state updates

2. homebridge-mqtt (dynamisch)

Gebruikt characteristic-level JSON berichten op homebridge/* topics:

• Command: homebridge/from/set met payload zoals {"name": "moonlight", "characteristic": "On", "value": true}
• State: homebridge/to/set voor het publiceren van je device state

Welke plugin gebruik je (of wil je gebruiken)? Dan kan ik je een aangepaste "hello world" maken die echt bij jouw setup past. De implementatie is behoorlijk verschillend van de Home Assistant code die ik eerder suggereerde.

De goede kant: je hebt al de MQTT infrastructure in je framework, dus het is vooral een kwestie van de juiste topics en payload formaten gebruiken! 🐰