Add Homecast integration

[robjampar]

Summary

Add a new integration for Homecast, which bridges Apple HomeKit smart home devices to open standards via a Mac/iOS relay app.

The integration connects to the Homecast API via OAuth 2.1 with PKCE and exposes HomeKit light devices as native Home Assistant entities. It supports two modes:

• Cloud mode — connects to api.homecast.cloud with WebSocket push for real-time state updates (<1s latency) and REST polling every 5 minutes as a safety net
• Community mode — connects to a local Mac server on the user's network

How it works

1. User adds integration via UI → selects Cloud or Community → OAuth 2.1 flow with PKCE
2. OAuth client is dynamically registered via RFC 7591 (no manual credential entry)
3. WebSocket connection established for real-time push updates
4. Individual characteristic changes applied incrementally to in-memory state
5. REST polling every 5 minutes as safety-net resync
6. Control commands sent via POST /rest/state

Uses pyhomecast as the third-party API client library.

Quality scale

Bronze tier checklist:

• action-setup (exempt - no additional actions)
• appropriate-polling (5 min safety-net, WebSocket push primary)
• brands
• common-modules
• config-flow-test-coverage
• config-flow
• dependency-transparency
• docs-actions (exempt - no additional actions)
• docs-high-level-description
• docs-installation-instructions
• docs-removal-instructions
• entity-event-setup
• entity-unique-id
• has-entity-name
• runtime-data
• test-before-configure
• test-before-setup
• unique-config-entry

Test plan

• Unit tests for config flow (cloud flow, menu, already configured, parameterized error tests, reauth, register client failure)
• Unit tests for init (setup, unload, connection error retry, auth error, token refresh errors)
• Unit tests for light platform (setup, brightness, HS color, color temp, turn on/off, color modes, multi-home)
• Unit tests for coordinator (WebSocket message handling, UUID mapping, group propagation, shutdown)
• Manual end-to-end testing against staging

Companion PRs:

• Branding: Add Homecast branding brands#10038
• Docs: Add Homecast integration documentation home-assistant.io#44342

[home-assistant]

Hi @robjampar

It seems you haven't yet signed a CLA. Please do so here.

Once you do that we will be able to review and accept this pull request.

Thanks!

[home-assistant]

Please take a look at the requested changes, and use the Ready for review button when you are done, thanks 👍

Learn more about our pull request process.

[home-assistant]

When adding new integrations, limit included platforms to a single platform. Please reduce this PR to a single platform

[Copilot]

Pull request overview

Adds a new Home Assistant core integration for the Homecast cloud service, enabling OAuth-based connectivity and exposing bridged HomeKit devices as native entities via periodic polling.

Changes:

• Introduces the homecast integration (OAuth2 + coordinator) and entity platforms (light, switch, climate, lock, cover, fan, alarm, sensors).
• Registers Homecast in generated integration/config-flow/application-credentials indices and updates CODEOWNERS.
• Adds unit tests and fixtures for config flow and config entry setup/unload.

Reviewed changes

Copilot reviewed 23 out of 26 changed files in this pull request and generated 9 comments.

Show a summary per file

File	Description
homeassistant/components/homecast/__init__.py	Integration setup/unload; OAuth session bootstrapping; coordinator wiring.
homeassistant/components/homecast/alarm_control_panel.py	Alarm control panel entity mapping and command sending.
homeassistant/components/homecast/application_credentials.py	OAuth2 authorization server + PKCE implementation hookup.
homeassistant/components/homecast/binary_sensor.py	Motion/contact/doorbell + low-battery binary sensor entities.
homeassistant/components/homecast/climate.py	Thermostat/climate entity mapping and setpoint control.
homeassistant/components/homecast/config_flow.py	OAuth2 config flow + connectivity validation + reauth steps.
homeassistant/components/homecast/const.py	Integration constants (API URLs, scopes, polling interval).
homeassistant/components/homecast/coordinator.py	Polling coordinator and state-setting helper.
homeassistant/components/homecast/cover.py	Cover entity mapping for blinds/window coverings.
homeassistant/components/homecast/entity.py	Base coordinator entity + device registry metadata + state write helper.
homeassistant/components/homecast/fan.py	Fan entity mapping and speed control.
homeassistant/components/homecast/light.py	Light entity mapping (brightness/HS/color temp) and control.
homeassistant/components/homecast/lock.py	Lock entity mapping and lock/unlock control.
homeassistant/components/homecast/manifest.json	Declares integration metadata and pyhomecast requirement.
homeassistant/components/homecast/quality_scale.yaml	Bronze quality scale checklist assertions/exemptions.
homeassistant/components/homecast/sensor.py	Temperature/illuminance sensors + companion battery level sensor.
homeassistant/components/homecast/strings.json	UI strings for config flow, abort reasons, and entry creation text.
homeassistant/components/homecast/switch.py	Switch/outlet entity mapping and on/off control.
homeassistant/generated/application_credentials.py	Adds homecast to application-credentials registry list.
homeassistant/generated/config_flows.py	Adds homecast to config-flow registry list.
homeassistant/generated/integrations.json	Registers homecast integration metadata for frontend/registry.
tests/components/homecast/__init__.py	Test package marker for the integration.
tests/components/homecast/conftest.py	Test fixtures: mock client/state and application credentials setup.
tests/components/homecast/test_config_flow.py	Tests OAuth config flow success + already-configured + error aborts.
tests/components/homecast/test_init.py	Tests config entry setup/unload and connection error retry.
CODEOWNERS	Adds code ownership for integration and its tests.

Stale

Stale

[erwindouna]

Thanks for contributing, @robjampar! Here's an initial review. :)

[robjampar]

@erwindouna I've addressed all your review comments — thanks for the detailed feedback! All CI is green and threads resolved. Ready for another look when you have time.