Shared clipboard

Punktfunk can share the clipboard between the machine you are sitting at and the host you are streaming. Copy a URL on your laptop, paste it into a browser on the host. Copy an error message on the host, paste it into a chat app on your laptop.

Two separate switches have to be on:

1. The host operator has to allow it, with a line in host.env and a host restart. This one is off by default.
2. You have to turn it on for that one host, in that host's edit sheet on your client. This one is off by default on the macOS, Windows and Linux clients — but on by default on Android.

Flipping one and not the other looks exactly like the feature not existing. So check both.

1. Allow it on the host

Add a PUNKTFUNK_CLIPBOARD line to the host's host.env — ~/.config/punktfunk/host.env on Linux, %ProgramData%\punktfunk\host.env on Windows.

PUNKTFUNK_CLIPBOARD=on

The accepted values:

Values are trimmed and compared case-insensitively. Anything the host doesn't recognise is treated as on — a typo like PUNKTFUNK_CLIPBOARD=yes or no-file enables the permissive policy rather than failing, so check the spelling if you meant text-only.

The file is only read at startup, so restart the host. On Linux:

systemctl --user restart punktfunk-host

On Windows, from an Administrator prompt:

punktfunk-host service restart

See Configuration for the rest of host.env.

About the file mode. No client shipping today asks for file transfer, and no host clipboard backend offers file formats yet. on and text-only therefore behave the same in practice — text-only is how you make that explicit and keep it that way.

2. Turn it on for that host, in your client

The client switch is per saved host, not global: handing a machine your clipboard is a decision about that machine. You set it in the host's edit sheet, and it is deliberately not something a settings profile can carry.

On Android the switch is only in the touch edit dialog. The controller/TV interface — what you get on Android TV, and on a phone when a controller is attached — has its own Edit Host screen with no clipboard row, so there is nowhere to change it there. It stays on, which is the Android default.

The setting is read when a session starts, so if you change it while streaming, reconnect.

macOS can also flip it mid-session: Stream ▸ Share Clipboard (⌃⌥⇧C), which becomes Stop Sharing Clipboard once the host has acknowledged it.

iOS, iPadOS, tvOS and the Steam Deck Decky plugin have no clipboard switch — see what each client does below.

Nothing crosses until something pastes

A copy costs nothing. When you copy, your machine announces only the list of formats it now holds — no bytes. The bytes are pulled across on a separate transfer, and only when an application on the other end actually pastes. Copying a large image and never pasting it transfers nothing.

That holds for everything you copy on your own machine, and for both directions on the host. It does not hold for a host copy arriving at a Windows or Android client: those two fetch the content straight away and put it on your local clipboard, whether or not you ever paste. On Windows that is because the lazy path needs Windows delayed rendering, which the client doesn't implement yet; on Android there is no way to satisfy a paste from the network at all. The macOS client is lazy in both directions.

A single transfer is capped at 64 MiB. Nothing else limits size, so a very large host-side copy can cross to a Windows or Android client for a paste that never happens.

What you copy on the macOS or Windows client is filtered for secrets: content marked org.nspasteboard.ConcealedType or org.nspasteboard.TransientType on macOS, or ExcludeClipboardContentFromMonitorProcessing on Windows — what password managers set — is never announced and never served. That check exists only in those two clients. The Android client has no equivalent, and neither does the host, so a password copied on the host is announced to your client like anything else.

The clipboard rides the native Punktfunk protocol's control channel, so it only exists in sessions from a Punktfunk client. A Moonlight client has no clipboard.

Which hosts and clients support it

Hosts. The host runs on Linux and Windows, and both have a clipboard backend — but on Linux it depends on the desktop session.

On Linux the host needs one of two mechanisms in the session it is streaming:

• ext-data-control-v1 — KWin, wlroots/Sway and Hyprland. Tried first.
• GNOME's own org.gnome.Mutter.RemoteDesktop.Session clipboard, used directly. Tried second.

The older zwlr-data-control-unstable-v1 is not implemented, so a compositor that offers only that has no backend. Neither does a gamescope session.

On Windows the host uses the Win32 clipboard, with delayed rendering so your content is only read when a host application pastes.

Clients, and what each one actually moves:

The Linux client has the switch but no working clipboard bridge: it enables the plane and then has no code to read or write the desktop's own clipboard, so nothing is announced and nothing is pasted. Turning it on there is harmless but has no effect today. The Decky plugin on the Steam Deck has no switch at all.

When you copy on the Windows client, images cross only if the copying application publishes the registered PNG clipboard format. Many Windows apps publish only a bitmap, and those copies aren't announced yet. The other direction is fine: an image copied on the host reaches the Windows client either way.

The host side is richer than any client: it can offer and accept text, HTML, RTF, PNG, JPEG and GIF. What you get is therefore whatever your client supports.

Why the toggle does nothing (or is greyed out)

On macOS, Stream ▸ Share Clipboard is greyed out whenever you are not streaming, or the connected host did not advertise a clipboard. On the other clients there is nothing to grey out — the per-host switch always looks available, and a host that can't do it simply does nothing. Work through these in order:

• The host has it off. The default. Nothing was added to host.env, or the value is off, 0, false or empty. Fix it with step 1 above.
• host.env was edited but the host wasn't restarted. The file is read once, at startup.
• The switch is off for this host in your client. It is per saved host, and off by default everywhere except Android. Check the host's Edit… sheet — step 2 above.
• The host's session has no supported backend. The host allows the clipboard, so it still advertises the capability, but it has nothing to read the desktop's clipboard with. This is a gamescope session, a compositor with only the old zwlr-data-control-unstable-v1, or a GNOME session whose Mutter doesn't expose the direct RemoteDesktop clipboard. Nothing on screen tells you this apart — the host log does.
• The host is older than the feature. A host from before clipboard sync never advertises it.
• Your client doesn't implement it — Linux, Steam Deck, iOS, iPadOS or tvOS. Nothing crosses regardless of what the host allows.
• You changed the switch while connected. Reconnect, or use ⌃⌥⇧C on macOS.
• The copy was a secret, or a format nobody handles. Concealed content is skipped on purpose on the macOS and Windows clients, and an image copied on Windows as a bare bitmap isn't announced.

Still stuck? The host log records what it decided on each session — a clipboard control line with the resolved state, and a clipboard backend unavailable line when the session had nothing to bind to. That is the fastest way to tell "off by policy" from "no backend" — see Troubleshooting.