ha-integration-knowledge

name	ha-integration-knowledge
description	Everything you need to know to build, test and review Home Assistant Integrations. If you're looking at an integration, you must use this as your primary reference.

File Locations

• Integration code: ./homeassistant/components/<integration_domain>/
• Integration tests: ./tests/components/<integration_domain>/

General guidelines

• When looking for examples, prefer integrations with the platinum or gold quality scale level first.
• Polling intervals are NOT user-configurable. Never add scan_interval, update_interval, or polling frequency options to config flows or config entries.
• Do NOT allow users to set config entry names in config flows. Names are automatically generated or can be customized later in UI. Exception: helper integrations may allow custom names.
• For entity actions and entity services, avoid requesting redundant defensive checks for fields already enforced by Home Assistant validation schemas and entity filters; only request extra guards when values bypass validation or are transformed unsafely.
• When validation guarantees a key is present, prefer direct dictionary indexing (data["key"]) over .get("key") so invalid assumptions fail fast.
• Integrations should be thin wrappers. Protocol parsing, device state machines, or other domain logic belong in a separate PyPI library, not in the integration itself. If unsure, ask before inlining.
• Integrations should not implement fixes or workarounds for limitations in libraries. Instead, the library should be updated to fix the issue.

The following platforms have extra guidelines:

• Diagnostics: platform-diagnostics.md for diagnostic data collection
• Repairs: platform-repairs.md for user-actionable repair issues

Entity platforms

• Ensure async_added_to_hass() and async_will_remove_from_hass() have symmetrical behavior. For example, if a subscription is created in async_added_to_hass(), it should be unsubscribed in async_will_remove_from_hass(). Also, if something is torn down in async_will_remove_from_hass(), it should be set up in async_added_to_hass().
• Entity base class (e.g. SensorEntity, TrackerEntity) provide a stable API for child classes to inherit from. Do not suggest redeclaring or duplicating attributes, properties, or methods the base class already provides, and do not add guards against the parent's behavior changing — rely on the base class instead.

Integration Quality Scale

• When validating the quality scale rules, check them at https://developers.home-assistant.io/docs/core/integration-quality-scale/rules
• When implementing or reviewing an integration, always consider the quality scale rules, since they promote best practices.

Template scale file: ./script/scaffold/templates/integration/integration/quality_scale.yaml

How Rules Apply

1. Check manifest.json: Look for "quality_scale" key to determine integration level
2. Bronze Rules: Always required for any integration with quality scale
3. Higher Tier Rules: Only apply if integration targets that tier or higher
4. Rule Status: Check quality_scale.yaml in integration folder for:
   • done: Rule implemented
   • exempt: Rule doesn't apply (with reason in comment)
   • todo: Rule needs implementation

Testing Requirements

• Tests should avoid interacting or mocking internal integration details. For more info, see https://developers.home-assistant.io/docs/development_testing/#writing-tests-for-integrations