Shared clipboard

Punktfunk can share the clipboard between the machine you are sitting at and the host you are streaming, in both directions — copy a URL on your laptop, paste it on the host, and back.

Two separate switches have to be on:

1. The host operator has to allow it, in the web console under Host → Settings. Off by default.
2. You have to turn it on for that one host, in that host's edit sheet on your client. Off by default on the macOS, Windows and Linux clients — on by default on Android.

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

1. Allow it on the host

Open the web console, go to Host → Settings, and set Shared clipboard to Text or Text and files. It applies to the next stream; no restart.

On a host nobody opens the console on, add a PUNKTFUNK_CLIPBOARD line to its host.env instead — ~/.config/punktfunk/host.env on Linux, %ProgramData%\punktfunk\host.env on Windows. A value set there wins over the console, which then shows the setting as locked.

PUNKTFUNK_CLIPBOARD=files

The accepted values:

Values are trimmed and compared case-insensitively. A value the host doesn't recognise is ignored with a warning in the host log, and the console's setting applies instead.

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, so files and text behave the same in practice — text makes that explicit and keeps 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 — so it lives in the host's edit sheet, deliberately not in a settings preset.

On Android the switch is only in the touch edit dialog. The controller/TV interface — Android TV, and a phone with a controller attached — has its own Edit Host screen with no clipboard row, so it stays on, 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. On an iPad with a hardware keyboard the same combo works, though there is no menu bar to show it in — and only while the pointer is released, as a captured session sends the keys to the host.

tvOS and a Steam Deck in Gaming Mode have no clipboard switch — the Apple TV has no pasteboard to share, and neither the Decky panel nor the client's console home has a host edit sheet — 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, 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 because the lazy path needs Windows delayed rendering, which the client doesn't implement yet; on Android because there is no way to satisfy a paste from the network at all. The macOS and iOS clients are lazy in both directions.

iOS has one deliberate exception. Backgrounding the app ends the session, so if the host copied something you have not pasted yet, those bytes are pulled across as the session ends, up to 8 MiB. That is what makes "copy on the host, switch to Safari, paste" work on an iPad. Nothing is fetched if you never leave the app, or if you already pasted.

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, iOS or Windows client is filtered for secrets: content marked org.nspasteboard.ConcealedType or org.nspasteboard.TransientType on the Apple clients, or ExcludeClipboardContentFromMonitorProcessing on Windows — what password managers set — is never announced and never served. That check exists only in those 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, which needs one of two mechanisms:

• 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. On a Steam Deck in Gaming Mode there is no switch at all — the Decky panel doesn't edit hosts — and since a Deck streams with that same Linux client, a switch there would have nothing to move anyway.

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 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 has nothing to read the desktop's clipboard with: 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 (GTK), Steam Deck 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.