homeassistant-ai/home-assistant-best-practices

Home Assistant Best Practices

Core principle: Use native Home Assistant constructs wherever possible. Templates bypass validation, fail silently at runtime, and make debugging opaque.

Decision Workflow

Follow this sequence when creating any automation:

0. Gate: modifying existing config?

If your change affects entity IDs or cross-component references — renaming entities, replacing template sensors with helpers, converting device triggers, or restructuring automations — read references/safe-refactoring.md first. That reference covers impact analysis, device-sibling discovery, and post-change verification. Complete its workflow before proceeding.

Steps 1-5 below apply to new config or pattern evaluation.

1. Check for native condition/trigger

Before writing any template, check references/automation-patterns.md for native alternatives.

Common substitutions:

• {{ states('x') | float > 25 }} → numeric_state condition with above: 25
• {{ is_state('x', 'on') and is_state('y', 'on') }} → condition: and with state conditions
• {{ now().hour >= 9 }} → condition: time with after: "09:00:00"
• wait_template: "{{ is_state(...) }}" → wait_for_trigger with state trigger (caveat: different behavior when state is already true — see references/safe-refactoring.md#trigger-restructuring)

2. Check for built-in helper or Template Helper

Before creating a template sensor, check references/helper-selection.md.

Common substitutions:

• Sum/average multiple sensors → min_max integration
• Binary any-on/all-on logic → group helper
• Rate of change → derivative integration
• Cross threshold detection → threshold integration
• Consumption tracking → utility_meter helper

If no built-in helper fits, use a Template Helper — not YAML. Create it via the HA config flow (MCP tool or API) or via the UI: Settings → Devices & Services → Helpers → Create Helper → Template. Only write template: YAML if explicitly requested or if neither path is available.

3. Select correct automation mode

Default single mode is often wrong. See references/automation-patterns.md#automation-modes.

| Scenario | Mode | |----------|------| | Motion light with timeout | restart | | Sequential processing (door locks) | queued | | Independent per-entity actions | parallel | | One-shot notifications | single |

4. Use entity_id over device_id

device_id breaks when devices are re-added. See references/device-control.md.

Exception: Zigbee2MQTT autodiscovered device triggers are acceptable.

5. For Zigbee buttons/remotes

• ZHA: Use event trigger with device_ieee (persistent)
• Z2M: Use device trigger (autodiscovered) or mqtt trigger

See references/device-control.md#zigbee-buttonremote-patterns.

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Critical Anti-Patterns

| Anti-pattern | Use instead | Why | Reference | |--------------|-------------|-----|-----------| | condition: template with float > 25 | condition: numeric_state | Validated at load, not runtime | references/automation-patterns.md#native-conditions | | wait_template: "{{ is_state(...) }}" | wait_for_trigger with state trigger | Event-driven, not polling; waits for change (see references/safe-refactoring.md#trigger-restructuring for semantic differences) | references/automation-patterns.md#wait-actions | | device_id in triggers | entity_id (or device_ieee for ZHA) | device_id breaks on re-add | references/device-control.md#entity-id-vs-device-id | | mode: single for motion lights | mode: restart | Re-triggers must reset the timer | references/automation-patterns.md#automation-modes | | enabled: false as a top-level key in automations.yaml | automation.turn_off (temporary) or entity registry disable (permanent) | Not a valid top-level key — rejected during schema validation; automation loads as unavailable | references/automation-patterns.md#disabling-automations | | Template sensor for sum/mean | min_max helper | Declarative, handles unavailable states | references/helper-selection.md#numeric-aggregation | | Template binary sensor with threshold | threshold helper | Built-in hysteresis support | references/helper-selection.md#threshold | | Renaming entity IDs without impact analysis | Follow references/safe-refactoring.md workflow | Renames break dashboards, scripts, scenes, Config-Entry data, and storage dashboards silently | references/safe-refactoring.md#entity-renames | | Renaming members of Config-Entry-based groups (UI groups) without updating membership | Update group membership via Options Flow after the registry rename | The entity registry rename does not update options.entities in the Config Entry — group silently breaks | references/safe-refactoring.md#config-entry-groups | | Renaming entities used by Config-Entry integrations (Better/Generic Thermostat, Min/Max, Threshold) without patching Config-Entry data | Scan and patch core.config_entries data+options fields | These integrations store entity_ids in Config Entry — not updated by entity registry renames | references/safe-refactoring.md#config-entry-data--blind-spots-for-entity-registry-renames | | template: sensor/binary sensor in YAML | Template Helper (UI or config flow API) | Requires file edit and config reload; harder to manage | references/template-guidelines.md | | Editing .storage/ files or other HA internal state directly | Use the HA REST/WebSocket API to manage state and config entries | .storage/ files are HA's internal state database; direct edits bypass validation, risk corruption, and can be silently overwritten by HA | — | | Writing raw YAML to configuration.yaml by hand for YAML-only integrations | Use managed YAML config editing with backup and validation | Unmanaged writes risk syntax errors, have no backup, and skip check_config — managed editing provides all three | references/yaml-only-integrations.md | | Generating YAML snippets for automations/scripts/scenes | Use the HA config API to create automations/scripts programmatically | API calls validate config, avoid syntax errors, and don't require manual file edits or restarts | references/automation-patterns.md, references/examples.yaml | | Telling user to edit configuration.yaml for integrations | Direct user to Settings > Devices & Services in the HA UI | Most integrations are UI-configured; YAML integration config is rare and integration-specific | — | | Referring to HA "add-ons" | Use the term "Apps" | HA renamed add-ons to Apps in 2026.2 — "Apps are standalone applications that run alongside Home Assistant" | — | | vacuum.send_command with vendor room IDs | vacuum.clean_area with HA area_id (if segments are mapped) | Uses native HA areas, works across integrations — but requires segment-to-area mapping in entity settings first | references/device-control.md#vacuum-control | | Using color_temp (mireds) in light service calls | Use color_temp_kelvin | The color_temp parameter was removed in 2026.3; only Kelvin is supported | references/device-control.md#lights | | Person/Device Tracker entered_home/left_home device triggers or is_home/is_not_home conditions | state trigger to: home / to: not_home, or state condition | These were removed in 2026.5 — state triggers and conditions are the correct replacements | references/automation-patterns.md#presence-and-person-triggers-and-conditions-removed-in-20265 | | Registering callbacks or calling self.turn_on()/self.get_state() in __init__() | Register everything in initialize() | Plugin connection not established during __init__ — calls fail silently | references/appdaemon.md#app-structure-and-lifecycle | | Calling run_in on repeated triggers without cancelling the previous handle | cancel_timer(self._off_handle) before each new run_in | Every trigger stacks an independent timer — devices toggle unpredictably | references/appdaemon.md#scheduling-and-timers | | Storing persistent state in instance variables | Use HA input_number, input_boolean, or input_text helpers | Instance variables reset on app reload or daemon restart | references/appdaemon.md#state-management-and-inter-app-communication | | Hardcoding entity IDs inside the class body | Pass entity IDs via self.args in apps.yaml | Hardcoded IDs prevent reuse and require code edits per installation | references/appdaemon.md#appsyaml-configuration |

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Reference Files

Read these when you need detailed information:

| File | When to read | Key sections | |------|--------------|--------------| | references/safe-refactoring.md | Renaming entities, replacing helpers, restructuring automations, or any modification to existing config | #universal-workflow, #entity-renames, #helper-replacements, #trigger-restructuring, #config-entry-data--blind-spots-for-entity-registry-renames, #storage-mode-dashboards-storagelovelace | | references/automation-patterns.md | Writing triggers, conditions, waits, or choosing automation modes; disabling automations | #native-conditions, #trigger-types, #wait-actions, #automation-modes, #continue-on-error, #repeat-actions, #ifthen-vs-choose, #trigger-ids, #disabling-automations | | references/helper-selection.md | Deciding whether to use a built-in helper vs template sensor | #menu-based-helpers, #numeric-aggregation, #rate-and-change, #time-based-tracking, #counting-and-timing, #scheduling, #entity-grouping, #data-smoothing, #random-values, #climate-control, #domain-conversion, #template-helpers, #decision-matrix | | references/template-guidelines.md | Confirming templates ARE appropriate for a use case | #when-templates-are-appropriate, #when-to-avoid-templates, #template-sensor-best-practices, #common-patterns, #error-handling | | references/yaml-only-integrations.md | Creating or editing YAML-only integrations that have no config flow (e.g. command_line, platform-based mqtt, rest) | #yaml-only-integration-types, #post-edit-actions | | references/device-control.md | Writing service calls, Zigbee button automations, or using target: | #entity-id-vs-device-id, #service-calls-best-practices, #zigbee-buttonremote-patterns, #domain-specific-patterns | | references/dashboard-guide.md | Designing or modifying Lovelace dashboards — layout, view types, sections, custom cards, CSS styling, HACS | #dashboard-structure, #view-types, #built-in-cards, #features, #custom-cards, #css-styling, #common-pitfalls | | references/dashboard-cards.md | Looking up available card types or fetching card-specific documentation | — | | references/domain-docs.md | Looking up integration or domain documentation for service calls, entity attributes, or configuration | — | | references/examples.yaml | Need compound examples combining multiple best practices | — | | references/appdaemon.md | AppDaemon apps: when to use vs. native HA, app structure, service calls, scheduling, error handling, safe refactoring impact | — |