Automating screenshots with Claude Code

-- https://quobix.com/articles/screenshots-with-claude-code/
-- ============================================================================
-- Screenshot to Claude Code
-- ============================================================================
-- Captures a screen selection and automatically pastes it into Claude Code
-- running in Ghostty terminal. Press Cmd+Shift+6 from any application.
--
-- State: prevents multiple screenshots from running simultaneously
local screenshotInProgress = false

-- State: tracks the most recently focused Ghostty window so we can paste
-- to the correct window even when triggering from another application
local lastGhosttyWindow = nil

-- Resets the in-progress flag. Centralized to ensure all code paths
-- properly release the lock, preventing the hotkey from getting stuck.
local function resetFlag()
    screenshotInProgress = false
end

-- Finds the Ghostty application by name or bundle ID.
-- Tries common name first, falls back to bundle ID for reliability.
local function findGhostty()
    return hs.application.find("Ghostty") or
           hs.application.find("com.mitchellh.ghostty")
end

-- Validates that a window reference is still valid and usable.
-- Windows can be closed between when we capture a reference and when
-- we try to use it, so we must validate before each operation.
local function isValidWindow(window)
    return window and window:application() and window:isStandard()
end

-- Window Tracking
local windowFilter = hs.window.filter.new("Ghostty")

-- Track when a Ghostty window gains focus
windowFilter:subscribe(hs.window.filter.windowFocused, function(window)
    if isValidWindow(window) then
        lastGhosttyWindow = window
    end
end)

-- Clean up stale references when windows are closed.
-- This prevents memory leaks from holding references to destroyed windows.
windowFilter:subscribe(hs.window.filter.windowDestroyed, function(window)
    if lastGhosttyWindow == window then
        lastGhosttyWindow = nil
    end
end)

-- Pastes the clipboard contents into the target Ghostty window.
-- Called after screenshot capture completes successfully.
local function pasteToGhostty()
    local targetWindow = lastGhosttyWindow

    -- If tracked window is no longer valid, find any valid Ghostty window
    if not isValidWindow(targetWindow) then
        local ghostty = findGhostty()
        if ghostty then
            local windows = ghostty:allWindows()
            for _, win in ipairs(windows) do
                if isValidWindow(win) then
                    targetWindow = win
                    break
                end
            end
        end
    end

    -- Bail out if no valid Ghostty window exists
    if not isValidWindow(targetWindow) then
        resetFlag()
        return
    end

    -- Focus the window; bail if focus fails
    local focusSuccess = targetWindow:focus()
    if not focusSuccess then
        resetFlag()
        return
    end

    -- Wait for window to fully activate, then send Ctrl+V to paste.
    -- The delay is necessary because macOS window focus is asynchronous.
    hs.timer.doAfter(0.2, function()
        -- Re-validate window hasn't been closed during the delay
        if isValidWindow(targetWindow) then
            hs.eventtap.keyStroke({"ctrl"}, "v")
        end
        resetFlag()
    end)
end

-- Callback invoked when screencapture command completes.
-- Exit code 0 = success, non-zero = user cancelled or error.
local function onScreenshotComplete(exitCode)
    if exitCode ~= 0 then
        resetFlag()
        return
    end

    -- Small delay to ensure clipboard is populated before pasting
    hs.timer.doAfter(0.1, pasteToGhostty)
end

-- ----------------------------------------------------------------------------
-- Hotkey Binding
-- ----------------------------------------------------------------------------
-- Cmd+Shift+6: Trigger screenshot selection, auto-paste to Ghostty
--
-- We use screencapture with these flags:
--   -c : Send capture to clipboard (not file)
--   -s : Interactive selection mode (like Cmd+Shift+4)
--   -x : Disable capture sound

hs.hotkey.bind({"cmd", "shift"}, "6", function()
    -- Prevent concurrent captures
    if screenshotInProgress then return end
    screenshotInProgress = true

    -- Launch macOS screencapture tool
    local task = hs.task.new("/usr/sbin/screencapture", onScreenshotComplete, {"-c", "-s", "-x"})
    if not task:start() then
        resetFlag()
    end
end)