Service Call

HA NOVA Service Call

Scope

Direct device/service control:

• call any HA service (light.turn_on, climate.set_temperature, etc.)
• list available services
• target by entityid, areaid, or device_id

No config mutations (use ha-nova:write for automation/script changes).

Bootstrap (once per session)

Verify relay CLI: ha-nova relay health If this fails: ha-nova setup

Relay Contract

Use file-based payloads for service writes:

• ha-nova relay core --method POST --path /api/services/... --body-file
• ha-nova relay core --method GET --path /api/states/
• --out when the response is large

Flow

1. Resolve target entity (use entity discovery if name is ambiguous).
2. If service is unclear, list available services for the domain:

• ha-nova relay core --method GET --path /api/services
• Filter by relevant domain.

1. If the user names a room/area but the intended scope could be narrower, ask one clarifying question before using area_id.

• Do not ask a second blocking ambiguity question in the same turn.
• If entity resolution already consumed the one blocking question, default to the narrower confirmed target or stop and explain the ambiguity.

1. Preview the service call:

• Before preview: read current state via ha-nova relay core --method GET --path /api/states/{entity_id}.
• If service changes an attribute present in the service call parameters (brightness, temperature, position, hvacmode, etc.) OR inherently changes entity state (toggle, turnon, turn_off, press, lock, unlock, open, close), show state delta before the call details:

`` **State delta:** brightness: 100% → 40% ``

• Attribute display rules:
• Brightness: HA uses 0-255 internally. ALWAYS show delta in %: brightness: 100% → 40% (not raw 0-255). If light is off (brightness null or absent), treat as 0%: brightness: 0% → 40%.
• Temperature: Show with unit: 22.5°C → 19°C. Note: temperature = setpoint (what we're changing), current_temperature = sensor reading (do NOT use for delta).
• Cover position: position: 100% (open) → 30%.
• State / mode: For parameterless state-changing services (toggle, turnon, turnoff, press, lock, unlock), always show state delta: on → off. For mode changes, show: hvac_mode: heat → cool.
• Entity unavailable → show delta as unavailable → {target} with warning: "Device is offline or unreachable."
• Entity unknown → show delta as unknown → {target} with info: "State not yet known (HA may not have polled yet). Service call may still work."
• State read failed → preview without delta, do not block.
• Show: service (domain.service), target (entity_id), data fields.
• Ask for natural confirmation.

1. Execute:

• ha-nova relay core --method POST --path /api/services/{domain}/{service} --body-file

1. Verify result:

• Check entity state after call: ha-nova relay core --method GET --path /api/states/{entity_id}
• Report: service called, new state, any errors.

Service Data Fields

Common patterns:

• light.turn_on: brightness (0-255), color_temp (mireds), rgb_color ([r,g,b])
• climate.set_temperature: temperature, hvac_mode
• switch.toggle: no extra fields needed
• cover.set_cover_position: position (0-100)

If unsure about required fields, check /api/services response for the service schema.

Helper Service Patterns

Common service calls for helper entities:

• input_boolean: input_boolean.turn_on, input_boolean.turn_off, input_boolean.toggle
• input_number: input_number.set_value (value), input_number.increment, input_number.decrement
• input_text: input_text.set_value (value)
• input_select: input_select.select_option (option), input_select.select_first, input_select.select_last, input_select.select_next, input_select.select_previous
• input_datetime: input_datetime.set_datetime (date, time, or datetime)
• input_button: input_button.press
• counter: counter.increment, counter.decrement, counter.reset, counter.set_value (value)
• timer: timer.start (optional duration), timer.pause, timer.cancel, timer.finish, timer.change (duration)
• schedule: schedule.reload (reloads all schedule entities from config)

Example:

{"method":"POST","path":"/api/services/input_number/set_value","body":{"entity_id":"input_number.target_temperature","value":22.5}}

For helper CRUD (create/update/delete helpers themselves), use ha-nova:helper instead.

Safety

• Preview every service call before execution.
• Never guess entity IDs; resolve or ask.
• No token confirmation needed (service calls are reversible actions).
• For potentially disruptive services (e.g., homeassistant.restart), warn and ask for explicit confirmation.

Error Handling

• 400/VALIDATION_ERROR: invalid request shape — check path and body format
• 404/NOT_FOUND: entity or service does not exist — re-resolve
• 502/UPSTREAM_WS_ERROR or 504/TIMEOUT: relay lost connection to HA — retry once, then report failure
• State verification failure (state didn't change): report discrepancy, do not retry automatically

Guardrails

• One entity at a time unless user explicitly requests batch (array entity_id supported).
• Verify state change after call.
• If state didn't change as expected, report discrepancy.

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: markusleben
• Source: markusleben/ha-nova
• License: MIT
• Homepage: https://github.com/markusleben/ha-nova

Install and usage instructions live in the source repository linked above.