YAML input helpers are registered but unavailable on Core 2026.9.1, work again on 2026.8.3

## The problem

After upgrading Home Assistant Core from **2026.8.3 to 2026.9.1**, YAML-defined helpers such as input_boolean, input_number and input_text are no longer available at runtime.

The entities are created in the Entity Registry and appear under:

**Settings → Devices & services → Entities**
but they show:
This entity is unavailable
At the same time, the entities do **not** exist under:
**Developer Tools → States**
The configuration passes ha core check successfully.
I reproduced the issue with a minimal input_boolean directly inside configuration.yaml, so the problem is not limited to packages or to my larger YAML configuration.
After downgrading Home Assistant Core back to **2026.8.3 without changing the configuration**, all YAML helpers immediately became available again.

---

## What version of Home Assistant Core has the issue?
2026.9.1
## What was the last working version of Home Assistant Core?
2026.8.3
## Home Assistant installation type
Home Assistant OS
## System information

Core: 2026.9.1
Supervisor: 2026.09.0
Operating System: 18.2
Installation method: Home Assistant OS
Architecture: amd64
Machine: qemux86-64

---
## Minimal configuration to reproduce
The issue can be reproduced without packages using only:
default_config:
input_boolean:
visu_direkt_test:
name: "VISU Direkt Test"
After a full restart on Core 2026.9.1:
* input_boolean.visu_direkt_test appears in the Entity Registry
* the entity is shown as unavailable
* input_boolean.visu_direkt_test does not exist under Developer Tools → States

ha core check reports:
Command completed successfully.

---
## Package configuration

The original problem was noticed with YAML packages.

configuration.yaml:

default_config:

homeassistant:
packages: !include_dir_named packages

Example package:

input_boolean:
visu_package_test:
name: "VISU Package Test"

The package entity shows the same behavior as the directly configured entity.

---

## Entity Registry information

The directly configured test entity is successfully registered:

entity_id: input_boolean.visu_direkt_test
platform: input_boolean
config_entry_id: null
disabled_by: null
hidden_by: null
unique_id: visu_direkt_test

The package test entity is also registered:

entity_id: input_boolean.visu_package_test
platform: input_boolean
config_entry_id: null
disabled_by: null
hidden_by: null
unique_id: visu_package_test

Therefore the YAML configuration appears to be read and the entities are registered, but no runtime state is created.

---

## Steps to reproduce

1. Run Home Assistant Core 2026.9.1.
2. Add the following to configuration.yaml:

input_boolean:
visu_direkt_test:
name: "VISU Direkt Test"

3. Run:

ha core check

Result:

Command completed successfully.

4. Fully restart Home Assistant.
5. Open Settings → Devices & services → Entities.
6. input_boolean.visu_direkt_test` exists but is unavailable.
7. Open Developer Tools → States.
8. input_boolean.visu_direkt_test` does not exist.

---

## Troubleshooting already performed
* Full Home Assistant restart
* ha core check successful
* Tested helper directly in configuration.yaml
* Tested helper through homeassistant.packages
* Verified Entity Registry entries
* Verified disabled_by: null
* Verified hidden_by: null
* Renamed and moved package files
* Temporarily removed KNX configuration and restarted
* No change
* Checked logs for:

* input_boolean
* input_number
* input_text
* package errors
* invalid configuration
* setup failures
* blocked startup
* No relevant helper setup error was found
* No Something is blocking Home Assistant from wrapping up the start up phase message was present

There are unrelated warnings/errors from custom integrations, but no error referring to the YAML helper setup itself.

---

## A/B test

### Core 2026.9.1

With the configuration above:

YAML accepted: yes
Entity Registry entry: yes
Entity disabled: no
Entity hidden: no
Runtime state: no
Entity available: no

### Core 2026.8.3

I downgraded Core from 2026.9.1 to 2026.8.3 and did **not change the YAML configuration**.

After loading Home Assistant again:

input_boolean.visu_direkt_test: available
package input_booleans: available
package input_numbers: available
package input_texts: available

All previously unavailable YAML helpers immediately worked again.

This appears to be a regression introduced in the **2026.9.x Core series**.

### What version of Home Assistant Core has the issue?

2026.9.1

### What was the last working version of Home Assistant Core?

2026.8.3

### What type of installation are you running?
Home Assistant OS
### Integration causing the issue
_No response_
### Link to integration documentation on our website
_No response_
### Diagnostics information
_No response_
### Example YAML snippet
yaml
### Anything in the logs that might be useful for us?
### Additional information
_No response_

Start with the minimal input_boolean in configuration.yaml on Core 2026.9.1, run ha core check, and fully restart Home Assistant. Compare the entity registry and Developer Tools → States behavior with Core 2026.8.3, then trace the YAML helper setup path responsible for creating runtime state. Done means direct and package-defined input_boolean, input_number, and input_text helpers are available at runtime again without configuration changes.

Written by the indexing model from the issue text.