Add ventilation preset modes to Duco fan entity

[ronaldvdmeer]

Proposed change

Extends the Duco fan entity with ventilation preset modes so users can set named ventilation levels from the UI and automations.

Previously the fan entity only exposed the speed slider (CNT1/CNT2/CNT3 → 33 %/66 %/100 %). This PR adds preset mode support:

Preset key	Label	API state (write)
auto	Auto	AUTO
man1	Timed low speed	MAN1
man2	Timed medium speed	MAN2
man3	Timed high speed	MAN3
empt	Empty house	EMPT

Reading state back:

• The MAN1x2/MAN1x3, MAN2x2/MAN2x3, and MAN3x2/MAN3x3 timed-variant states are mapped back to their base preset (man1, man2, man3).
• AUT1/AUT2/AUT3 (automatic boost states triggered by sensor modules) are mapped back to the auto preset. They cannot be set from Home Assistant.

Speed slider vs. presets:
The percentage slider and presets are intentionally separate control paths. The slider always issues a continuous override (CNT), while presets issue a timed override (MAN). MAN states do not expose a percentage value — using the slider from a MAN preset transitions to a CNT state.

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 #
• This PR is related to issue:
• Link to documentation pull request: Add Duco fan preset mode documentation home-assistant.io#45153
• 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.
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• 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.

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[Copilot]

Pull request overview

This PR extends the Duco integration’s fan entity to expose named ventilation presets in addition to the existing percentage-based speed control, so Home Assistant users can select Duco-specific ventilation modes from the UI and automations.

Changes:

• Added Duco fan preset constants and state mappings for auto, man1, man2, man3, and empt.
• Updated the fan entity to report/set preset modes and kept percentage control for continuous speed states.
• Added user-facing preset labels and updated Duco fan tests/snapshots for the new preset list.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 3 comments.

File	Description
homeassistant/components/duco/fan.py	Adds preset-mode support and updates Duco ventilation state mapping logic for the fan entity.
homeassistant/components/duco/strings.json	Adds translated labels for the new fan preset modes.
tests/components/duco/test_fan.py	Expands fan service tests for the new preset commands and adjusts rate-limit logging assertions.
tests/components/duco/snapshots/test_fan.ambr	Updates the expected entity snapshot to include the new preset modes.

[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

[ronaldvdmeer]

Important

The percentage slider and presets are intentionally separate control paths on the Duco device. Adjusting the slider always issues a CNT (continuous) command, while presets always issue a MAN (timed) command. Showing a percentage value for a MAN state would imply they were set via the slider, which is misleading. The increase_speed edge case (starting from 0% when in a MAN preset) is acceptable: if a user calls increase_speed from a timed preset, transitioning to CNT1 is reasonable behavior.