Home Assistant Config Flow & Discovery

Use this skill when adding or adjusting setup flows, discovery handlers, options flows, or reauth for this integration.

When to Use

• Creating or refining config_flow.py
• Handling discovery sources (user, dhcp, zeroconf, integration discovery)
• Adding/updating options flow or reauth steps
• Ensuring duplicate prevention and IP-change handling are correct

Core Principles

• UI-first: No new YAML; all setup in the UI.
• Async-only: All I/O must be awaited; use executor only for blocking library work.
• One device, one entry: Abort duplicates; update existing entries when discovery reports a new host/IP.
• Stable identifiers: Use BLE-MAC (or WiFi MAC) for unique IDs; never pivot unique IDs on IP.
• Selectors > raw text: Prefer HA selectors for better UX and validation.

Step Patterns

• async_step_user: show form when user_input is None; on submit, validate connectivity; return errors with keys (cannot_connect, invalid_auth, already_configured).
• async_step_dhcp / async_step_zeroconf / async_step_integration_discovery: deduplicate via MAC/unique ID; if existing entry with new host, update data and abort with already_configured.
• async_step_confirm: for discovery flows, prefill known values and ask user to confirm.
• Unicast Marstek.GetDevice (manual IP/port, Confirm device, repairs) must call get_device_info(..., udp_client=get_udp_client(hass, bind_port_for_host(host, port))). Do not bind a second socket and do not pause for that probe. Pause pooled listeners only around broadcast discover_devices(). Pausing does not unbind; Linux SO_REUSEPORT still delivers the reply to the coordinator.

Reauth Flow Pattern

Reauth handles authentication/connection failures gracefully, allowing users to update credentials or IP addresses without removing the integration.

Implementation Steps

1. Entry point: async_step_reauth(entry_data) - Called when reauth is triggered
2. Confirm step: async_step_reauth_confirm(user_input) - Show form, validate, update entry

Code Pattern

from homeassistant.config_entries import SOURCE_REAUTH

async def async_step_reauth(
    self, entry_data: dict[str, Any]
) -> ConfigFlowResult:
    """Handle reauth when device becomes unreachable."""
    return await self.async_step_reauth_confirm()

async def async_step_reauth_confirm(
    self, user_input: dict[str, Any] | None = None
) -> ConfigFlowResult:
    """Confirm reauth dialog."""
    errors: dict[str, str] = {}
    reauth_entry = self._get_reauth_entry()

    if user_input is not None:
        host = user_input.get(CONF_HOST)
        try:
            device_info = await get_device_info(
                host=host, port=port, udp_client=udp_client
            )
            if device_info:
                # Validate unique ID unchanged
                await self.async_set_unique_id(device_info["ble_mac"])
                self._abort_if_unique_id_mismatch()
                # Preferred: use async_update_reload_and_abort helper
                return self.async_update_reload_and_abort(
                    reauth_entry,
                    data_updates={CONF_HOST: host},
                )
            errors["base"] = "cannot_connect"
        except (OSError, TimeoutError):
            errors["base"] = "cannot_connect"

    return self.async_show_form(
        step_id="reauth_confirm",
        data_schema=vol.Schema({vol.Required(CONF_HOST): cv.string}),
        errors=errors,
        description_placeholders={"host": reauth_entry.data.get(CONF_HOST, "")},
    )

Key Helpers

• self._get_reauth_entry() - Get the config entry being reauthenticated
• self.async_update_reload_and_abort() - Update entry, reload, and abort with reauth_successful (preferred)
• self._abort_if_unique_id_mismatch() - Ensure the same device is being reauthenticated
• Check source: if self.source == SOURCE_REAUTH:

Triggering Reauth

From coordinator or setup when connection fails repeatedly:

entry.async_start_reauth(hass)

Required Translations

Add to strings.json and translations/en.json:

"reauth_confirm": {
  "title": "Reconnect Device",
  "description": "The device at {host} is not responding.",
  "data": {"host": "IP address"}
}

And abort reason:

"abort": {
  "reauth_successful": "Device reconnected successfully"
}

Form Patterns

Grouping Input Fields (sections)

Use section() to group related fields into collapsible sections:

from homeassistant.data_entry_flow import section

data_schema = {
    vol.Required("host"): str,
    vol.Required("advanced_options"): section(
        vol.Schema({
            vol.Optional("timeout", default=30): int,
            vol.Optional("retry_count", default=3): int,
        }),
        {"collapsed": True},  # Initially collapsed
    )
}

Pre-filling Forms with Suggested Values

from homeassistant.helpers.schema_config_entry_flow import add_suggested_values_to_schema

return self.async_show_form(
    data_schema=add_suggested_values_to_schema(
        OPTIONS_SCHEMA, self.config_entry.options
    )
)

Browser Autofill

Use recognized keys (username, password) or TextSelector with autocomplete:

vol.Required(CONF_USERNAME): TextSelector(
    TextSelectorConfig(type=TextSelectorType.EMAIL, autocomplete="username")
),

Read-only Fields in Options

For frozen configuration shown in options:

vol.Optional(CONF_DEVICE_ID): EntitySelector(
    EntitySelectorConfig(read_only=True)
),

Navigation Menu

return self.async_show_menu(
    step_id="user",
    menu_options=["discovery", "manual"],
    description_placeholders={"model": "Venus A"},
)

Long-running Tasks (Show Progress)

if not self.task:
    self.task = self.hass.async_create_task(long_running_operation())
if not self.task.done():
    return self.async_show_progress(
        progress_action="connecting",
        progress_task=self.task,
    )
return self.async_show_progress_done(next_step_id="finish")

Options Flow

• Implement async_get_options_flow to return an OptionsFlowHandler.
• Store runtime preferences in entry.options; keep credentials in entry.data.
• Register entry.add_update_listener in __init__.py to reload on options change.
• Use selectors for numeric intervals, toggles, enums, and text fields where helpful.
• Use add_suggested_values_to_schema() to pre-fill current options.

Discovery Handling

• Manifest-driven discovery (dhcp/zeroconf/ssdp) should land in dedicated steps.
• The scanner handles IP changes; do not add fallback discovery inside coordinator updates.
• On discovery, set unique ID early and call self._abort_if_unique_id_configured().
• If the device is known but host changed, update the entry data and abort with already_configured.

Error Keys & Translations

• Define user-facing errors in strings.json and mirror to translations/en.json.
• Preferred keys: cannot_connect, invalid_auth, already_configured, unknown.
• Provide helpful description_placeholders when useful (e.g., {ip_address}).

Form Translation Structure

Config flow forms are translated via strings.json:

{
  "config": {
    "step": {
      "user": {
        "title": "Set up Marstek",
        "description": "Connect to your {model} device.",
        "data": {
          "host": "Hostname or IP",
          "port": "Port"
        },
        "data_description": {
          "host": "The IP address of your Marstek device on the local network"
        },
        "sections": {
          "advanced_options": {
            "name": "Advanced Options",
            "description": "Optional configuration"
          }
        }
      }
    },
    "error": {
      "cannot_connect": "Cannot connect to device",
      "invalid_auth": "Invalid authentication"
    },
    "abort": {
      "already_configured": "Device is already configured",
      "reauth_successful": "Reauthentication successful"
    }
  }
}

Form translation keys:

• title - Form title
• description - Form description (supports placeholders via description_placeholders)
• data - Field labels (keyed by field name)
• data_description - Field help text (shown below field)
• sections - Section names and descriptions (for section() fields)

Validation Checklist

• Unique ID set from BLE-MAC/WiFi MAC; duplicates abort
• User step validates connectivity asynchronously
• Discovery steps update existing entry on host/IP change
• Options flow reloads entry on change
• Reauth asks only for the changed credential
• Selectors used where appropriate; translations updated