Local Mode
Normally Homecast reaches your accessories through your relay: the app on your phone talks to homecast.cloud, which talks to the Mac running Homecast, which talks to Apple Home. That chain is what lets you control your home from anywhere — and it means that if the relay stops, everything stops with it.
Local Mode removes that dependency when it doesn't need to be there. If the device you're holding has access to the home in Apple Home, Homecast talks to Apple Home directly from that device instead.
It turns on by itself in two situations:
- Your relay is offline. Rather than showing you an error, Homecast carries on using the Apple Home access this device already has.
- You haven't set up a relay yet. Install Homecast on an iPhone, sign in, and your home is there straight away — nothing to configure first.
How you know it's on
A Local Mode badge appears next to the search icon and stays there for as long as it's active. Tap it to see which device is serving, why, and what is and isn't available.
The dot on the badge is green when your accessories have been matched to your Homecast layout, and amber when they haven't yet — see Names and layout below.
Requirements
Local Mode needs a device that can talk to Apple Home itself, which means:
| Device | Local Mode |
|---|---|
| iPhone or iPad running the Homecast app | Yes |
| A Mac running Homecast that isn't the relay | Yes |
| The relay Mac itself | Not needed — it already talks to Apple Home directly |
| Any web browser | No — browsers have no access to Apple Home |
The device must be signed in to an Apple Account that has been invited to the home in Apple's Home app, and must have granted Homecast permission to use it (Settings → Privacy & Security → Home). A home that isn't on this device's Apple Account can't be served locally.
You also need to be on the same network as your accessories, or have a home hub (HomePod or Apple TV) set up — this is Apple's requirement for remote access, and it's the same one the Apple Home app follows.
What works, and what doesn't
Local Mode covers everything that is a direct conversation with your accessories:
- Lights, switches, plugs, blinds and locks
- Sensors and thermostats
- Scenes, rooms and service groups
These stay with the relay and resume when it's back:
| Not available | Why |
|---|---|
| Automations | They run on the relay so they run once, for the whole household. A phone running them too would fire every automation more than once. |
| Notifications | Sent by Homecast's servers in response to relay-side automations. |
| Analytics recording | Recorded centrally. Charts you already have stay readable; the period the relay was down will show a gap. |
| MQTT and Home Assistant | Served by the relay and the cloud. |
| Sharing | Other people reach your home through the cloud, not through your phone. |
Automations you've set up in Apple's Home app are unaffected — those run on your home hub, not on Homecast.
Names and layout
Your Homecast layout — custom names, rooms, collections, ordering — is stored in your account, and Apple Home identifies the same accessory differently on every device. So when Local Mode starts, Homecast matches what this device can see against what your account already knows, and your home looks the way you arranged it.
Matching happens quietly in the background while you're online, so it's ready before you ever need it. It never changes anything in your account; it only looks things up.
If an accessory can't be matched it still works — it just shows its Apple Home name rather than the one you gave it. If Homecast can't reach its servers at all and has never matched this device before, everything works but shows Apple Home's names and arrangement until the device is next online. The badge turns amber when that's the case.
Choosing when it's used
Local Mode manages itself, and most people never need to touch it — it takes over when the relay can't be reached and steps back when it returns.
If you want to pin it on or off, turn on Developer Mode (Settings → Display), then open Settings → Local Mode:
| Setting | Behaviour |
|---|---|
| Automatic (default) | Takes over when the relay can't be reached, and steps back when it returns. |
| Always on | Always control Apple Home from this device, even when the relay is fine. |
| Off | Never — this device only ever goes through the relay. |
The same screen shows whether Local Mode is currently active and why, whether Homecast has permission to use Apple Home on this device, and how many of your accessories have been matched — with a Sync now button if you've just renamed or added something.
Turning Developer Mode back off only hides the screen; whatever you set stays in effect, and Local Mode keeps working either way.
Things worth knowing
On iPhone and iPad it works while the app is open. iOS suspends apps in the background, so Local Mode is a way to keep using your home, not a replacement for a relay. A relay is a Mac that stays awake precisely so something is always listening.
It doesn't switch back and forth. Homecast waits a few seconds before taking over and rather longer before handing back, so a relay that drops briefly won't make the interface flicker.
Other people aren't affected. Local Mode serves the device it's running on. Anyone else in the household still needs the relay, which is why it's worth getting the relay healthy rather than leaving Local Mode to cover for it — see Relay offline.
Next: Relay offline