---
name: Paste at cursor
type: architecture-map-page
slice: 02-tauri-runtime
last_verified: 2026/05/09
---

# `commands::paste`

> **Where you are:** [Architecture map](../../README.md) → [Tauri runtime](../README.md) → [Commands](README.md) → Paste

**Plain English summary.** Auto-insert-at-cursor: copy the transcript onto the clipboard and synthesise the platform's paste keystroke (Ctrl+V / Cmd+V) so the text lands in whatever app the user was already focused on. Adds a replace-with-raw flow that fires undo first. Skips the keystroke when the focused window is a terminal emulator (terminals duplicate the keystroke through the PTY). Hides the always-on-top preview overlay before the keystroke so a Wayland compositor doesn't accidentally route the paste back into Lumotia. Restores the user's prior clipboard 300 ms after the paste to honour the "never silently clobber the user's clipboard" contract.

## At a glance

- Path: `src-tauri/src/commands/paste.rs`.
- LOC: 790.
- Tauri commands exposed:
  - `paste_text(app, text: String) -> Result<PasteOutcome, String>`. Copy + paste at cursor. Returns a `PasteOutcome { backend, pasted, copied, message }`.
  - `paste_text_replacing(app, text: String) -> Result<PasteOutcome, String>`. Replace flow: undo → 60 ms gap → paste. Same return shape.
  - `detect_paste_backends() -> Vec<String>`. Pure probe used by Settings: returns the names of available backends on the current OS / session.
- Events emitted: none.
- Depends on: `arboard::Clipboard`, `tauri::Manager` (to find and hide the preview window), `std::process::Command` (every backend shells out).
- Called from frontend at: dictation result toast / replace-with-raw button (the two main user-facing actions).

## What's in here

### Constants (`src-tauri/src/commands/paste.rs:29`)

- `CLIPBOARD_RESTORE_MS = 300` — window after paste before restoring the user's prior clipboard.
- `PREVIEW_HIDE_SETTLE_MS = 80` — compositor settle time after hiding the preview overlay.
- `UNDO_PASTE_GAP_MS = 60` — gap between undo and follow-up paste in the replace flow (brief item #17).

### `PasteOutcome` (`src-tauri/src/commands/paste.rs:43`)

Frontend-facing struct: `backend: Option<String>` (e.g. `"wtype"`, `"xdotool"`, `"ydotool"`, `"osascript"`, `"sendkeys"`), `pasted: bool`, `copied: bool`, `message: Option<String>`.

### `paste_text` (`src-tauri/src/commands/paste.rs:67`)

Step-by-step:

1. Snapshot the current clipboard text via `arboard::Clipboard::get_text` (or `None` for non-text content).
2. Write the transcript onto the clipboard. If this fails, return immediately with `copied=false` and the error.
3. Probe the focused window via `detect_focused_terminal()`. If a known terminal class hits, return with a "Terminal detected" message; the user can finish manually with Ctrl+Shift+V or right-click. Note: prior clipboard is intentionally NOT restored here, because the user's recovery path needs the transcript on the clipboard.
4. `hide_preview_overlay_for_paste(&app).await` — find the `transcription-preview` window if it exists and is visible, hide it, sleep 80 ms.
5. `trigger_paste_keystroke()` — per-OS dispatch.
6. If the keystroke fired, schedule `restore_prior_clipboard` 300 ms later via a detached `tokio::spawn`.

### `paste_text_replacing` (`src-tauri/src/commands/paste.rs:185`)

Same shape as `paste_text` but with an extra step: after copying and hiding the preview, fire `trigger_undo_keystroke()`, sleep 60 ms, then paste. The undo removes whatever text Lumotia already inserted (the cleaned-up transcript), the paste inserts the raw text. Used by the "replace with raw" frontend button per brief item #17.

### `detect_paste_backends` (`src-tauri/src/commands/paste.rs:258`)

Pure probe: Linux returns the subset of `["wtype", "xdotool", "ydotool"]` that resolve via `command -v`; macOS always returns `["osascript"]`; Windows always returns `["sendkeys"]`. Settings uses this to tell the user "install wtype" when Linux is empty.

### Terminal classifier

- `KNOWN_TERMINAL_CLASSES` (`src-tauri/src/commands/paste.rs:292`) — substring list ordered longest-first so `windowsterminal` wins over `terminal`. Covers Windows (PowerShell, conhost, console, pwsh, cmd, WindowsTerminal), macOS (Terminal, iTerm, iTerm2), Linux (alacritty, konsole, gnome-terminal-server, kitty, wezterm, foot, st, urxvt, xterm, hyper, tilix).
- `classify_terminal(raw)` (`src-tauri/src/commands/paste.rs:331`) — case-insensitive substring search over the list.
- `detect_focused_window_class()` plus per-OS implementations (`:345`).

### Per-OS focused-window probes

- Linux X11: `xdotool getactivewindow getwindowclassname` (`:365`).
- Linux Wayland: returns `None`. No reliable probe from an unprivileged client. Documented as "by design".
- macOS: `osascript -e 'tell application "System Events" to get name of first application process whose frontmost is true'` (`:386`).
- Windows: PowerShell P/Invoke wrapper around `GetForegroundWindow` + `GetWindowThreadProcessId` + `Get-Process` (`:407`).

### Per-OS paste / undo backends

- Linux: `linux_paste` / `linux_undo` walk `pick_linux_backend_order` (`:502`), which flips the preference order based on session type (`wtype, ydotool, xdotool` for Wayland; `xdotool, ydotool, wtype` for X11). Each tool is invoked via `Command::new`; `wtype` uses `-M ctrl v -m ctrl`, `xdotool` uses `key ctrl+v`, `ydotool` uses raw linux input keycodes (`29:1 47:1 47:0 29:0`). Undo replaces V (47) with Z (44).
- macOS: `osascript -e 'tell ... to keystroke "v" using command down'` (`:594`). Undo swaps in `"z"`.
- Windows: `powershell -Command "(New-Object -ComObject WScript.Shell).SendKeys('^v')"` (`:634`). Undo uses `'^z'`.

### Helpers

- `snapshot_clipboard_text` (`:125`) — wraps arboard.
- `schedule_clipboard_restore` (`:137`) — fires a `tokio::spawn` that sleeps `CLIPBOARD_RESTORE_MS` and calls `restore_prior_clipboard`.
- `restore_prior_clipboard` (`:152`) — reads the current clipboard, calls `should_restore` (`:171`), and writes back the prior content if and only if the clipboard still holds the transcript we wrote (i.e. the user has not copied something else in the interim).
- `hide_preview_overlay_for_paste` (`:240`) — find the preview window, check visibility, hide, sleep 80 ms.

## Data flow

```
frontend invoke('paste_text', { text })
  -> snapshot clipboard
  -> write transcript to clipboard
  -> detect terminal: yes -> early return with "manual paste needed" message
  -> hide preview overlay (Wayland focus quirk)
  -> trigger paste keystroke per OS
  -> spawn 300 ms timer -> restore prior clipboard if clipboard still holds the transcript
  -> return PasteOutcome
```

Replace flow inserts an `undo` keystroke and a 60 ms gap between hide and paste.

## Watch-outs

- **Focus must already be on the target window when the keystroke fires.** The global hotkey flow preserves this naturally; clicking Lumotia's own UI does not. The frontend Settings page surfaces the caveat next to the toggle.
- **Wayland focused-window probe is intentionally absent.** No way to do this from an unprivileged Wayland client. Result: terminal detection on Wayland-Kitty users will miss; they fall back to the manual Ctrl+Shift+V they already use.
- **Clipboard restore is best-effort.** If the user copies something else within the 300 ms window, `should_restore` will (correctly) decline to write back. If a slow Wayland compositor delays the keystroke past 300 ms, we restore too early and the synthesised Ctrl+V pastes the user's old clipboard. Tradeoff documented in Handy #921.
- **Linux backend order is session-aware.** A user with `XDG_SESSION_TYPE=wayland` and only xdotool installed will fall through to xdotool with a warning; their X11-app focus on a Wayland session works fine but Wayland-native apps will not see the keystroke.
- **No backend = clipboard-only.** If `trigger_paste_keystroke` fails on Linux (no tools installed), the user still has the transcript on the clipboard; Settings shows the install-wtype hint via `detect_paste_backends`.
- **PowerShell process spawn cost on Windows.** Each paste spawns a fresh PowerShell. Acceptable for one-off paste invocations; if you ever build a streaming-paste mode, switch to native `SendInput` via the `windows` crate.
- **Permissions.** The macOS path requires the user to have granted Accessibility permissions to Lumotia (System Settings → Privacy → Accessibility). Without that, `osascript` returns success but the keystroke is silently dropped. There is no probe today; flag this in onboarding.

## See also

- [Window management](windows.md) — `transcription-preview` is the window that gets hidden by `hide_preview_overlay_for_paste`.
- [Small commands → clipboard](small-commands.md#clipboardrs) — the bare `copy_to_clipboard` command, used when the user explicitly wants clipboard-only.
- [Live transcription](live.md) — the upstream of the dictation result that gets pasted.
- [Hotkey bridge](hotkey.md) — the global hotkey path that preserves focus on the target window.
