Add support for dynamic nest devices and remove stale devices

[allenporter]

Proposed change

Update the nest integration to dynamically add and remove devices. Nest publishes a pubsub event when the devices change and the list of devices is refreshed.

Update the quality scale to match the new functionality. This includes marking existing device support as complete.

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New integration (thank you!)
• New feature (which adds functionality to an existing integration)
• Deprecation (breaking change to happen in the future)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Additional information

• This PR fixes or closes issue: fixes Device not removed from Google Nest integration #155640
• This PR is related to issue:
• Link to documentation pull request: Update Nest documentation to add dynamic device behavior home-assistant.io#42573
• Link to developer documentation pull request:
• Link to frontend pull request:

Checklist

• I understand the code I am submitting and can explain how it works.
• The code change is tested and works locally.
• Local tests pass. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.
• I have followed the development checklist
• I have followed the perfect PR recommendations
• The code has been formatted using Ruff (ruff format homeassistant tests)
• Tests have been added to verify that the new code works.
• Any generated code has been carefully reviewed for correctness and compliance with project standards.

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated for www.home-assistant.io

If the code communicates with devices, web services, or third-party tools:

• The manifest file has all fields filled out correctly.
  Updated and included derived files by running: python3 -m script.hassfest.
• New or updated dependencies have been added to requirements_all.txt.
  Updated by running python3 -m script.gen_requirements_all.
• For the updated dependencies - a link to the changelog, or at minimum a diff between library versions is added to the PR description.

To help with the load of incoming pull requests:

• I have reviewed two other open pull requests in this repository.

[Copilot]

Pull request overview

This PR adds dynamic device management to the Nest integration, enabling automatic addition of newly discovered devices and removal of stale devices that no longer exist. The integration now listens for device changes from the Nest API and updates the Home Assistant device registry accordingly.

Key changes:

• Implemented a callback-based listener pattern for device additions across all platforms (sensor, climate, camera)
• Added automatic stale device cleanup when devices are no longer returned by the Nest API
• Updated quality scale to mark devices, stale-devices, and dynamic-devices as complete

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
homeassistant/components/nest/__init__.py	Implements device listener registration and callback system; handles dynamic device addition and stale device removal
homeassistant/components/nest/types.py	Adds type definitions for device listener callbacks
homeassistant/components/nest/sensor.py	Migrates from direct device iteration to listener-based pattern
homeassistant/components/nest/climate.py	Migrates from direct device iteration to listener-based pattern
homeassistant/components/nest/camera.py	Migrates from direct device iteration to listener-based pattern
homeassistant/components/nest/quality_scale.yaml	Updates quality scale rules to mark device-related features as complete
tests/components/nest/test_init.py	Adds comprehensive tests for dynamic device addition and stale device cleanup
tests/components/nest/test_events.py	Updates comment to reflect new automatic entity registration behavior