feat: make the clipboard work across tmux, ssh and hosts

tmux copy bindings piped to xclip, which is X11-only and never worked
under Hyprland or over SSH, and set-clipboard was never enabled, so the
vi-mode `y` binding was dead too. Route both through OSC 52 instead.
terminal-features has to name the outer terminal explicitly: tmux skips
OSC 52 silently when the terminfo entry does not claim the capability,
which is the common case for an SSH session on xterm-256color.

Neovim only falls back to OSC 52 when it finds no clipboard tool, but
wl-clipboard is installed on every host, so over SSH it wrote the remote
clipboard. Pin the OSC 52 provider for SSH sessions only.

Moonlight and Sunshine have no clipboard channel in the protocol, so
nothing at the terminal layer can help there. Add kdeconnect on all three
hosts for that, and start its indicator from Hyprland — kdeconnectd is
DBus-activated and nothing else brings it up at login.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

home/common/programs/hyprland/default.nix

@@ -219,6 +219,9 @@ in
           hl.exec_cmd("hyprctl setcursor Nordzy-cursors ${toString cfg.cursorSize}")
           hl.exec_cmd("hyprsunset")
           hl.exec_cmd("noctalia")
+          -- kdeconnectd is only DBus-activated; nothing starts it at login,
+          -- so clipboard sync stays dead until the indicator runs.
+          hl.exec_cmd("kdeconnect-indicator")
         end)
 
         -- layer rules

home/common/programs/neovim/default.nix

@@ -12,5 +12,14 @@
 
   programs.nvchad = {
     enable = true;
+
+    # Neovim only auto-picks OSC 52 when it finds no clipboard tool, but
+    # wl-clipboard is on every host — so over SSH it writes the *remote*
+    # clipboard instead. Locally wl-copy stays: kitty refuses OSC 52 reads.
+    extraConfig = ''
+      if vim.env.SSH_TTY and vim.env.SSH_TTY ~= "" then
+        vim.g.clipboard = "osc52"
+      end
+    '';
   };
 }

home/common/programs/tmux.conf

@@ -101,6 +101,20 @@ setw -g mode-keys vi
 bind -T copy-mode-vi v send -X begin-selection
 bind -T copy-mode-vi y send -X copy-selection-and-cancel
 
+# -------------------------------------------------------------------
+# Clipboard (OSC 52)
+# -------------------------------------------------------------------
+set -g set-clipboard on
+
+# tmux silently skips OSC 52 unless the outer terminal's terminfo claims the
+# capability. kitty's does; SSH sessions usually land on a bare
+# xterm-256color that does not, so declare both.
+set -ag terminal-features ",xterm-kitty:clipboard"
+set -ag terminal-features ",xterm-256color:clipboard"
+
+# Let nvim's OSC 52 provider reach the outer terminal through tmux.
+set -g allow-passthrough on
+
 
 # tmux-resurrect settings
 set -g @resurrect-capture-pane-contents 'on'
@@ -142,7 +156,9 @@ bind-key -T copy-mode-vi WheelDownPane send-keys -X scroll-down
 bind-key -T copy-mode WheelUpPane send-keys -X scroll-up
 bind-key -T copy-mode WheelDownPane send-keys -X scroll-down
 
-# Clipboard integration (drag-to-copy)
-bind-key -T copy-mode-vi MouseDragEnd1Pane send-keys -X copy-pipe-and-cancel "xclip -in -selection clipboard"
-bind-key -T copy-mode MouseDragEnd1Pane send-keys -X copy-pipe-and-cancel "xclip -in -selection clipboard"
+# Clipboard integration (drag-to-copy). No external command: set-clipboard
+# above routes this through OSC 52, which works on Wayland and over SSH.
+# xclip did neither.
+bind-key -T copy-mode-vi MouseDragEnd1Pane send-keys -X copy-pipe-and-cancel
+bind-key -T copy-mode MouseDragEnd1Pane send-keys -X copy-pipe-and-cancel
 # End agent-deck configuration