Document why cache dir uses ~/.cache/ instead of ~/Library/Caches/ (#4)

The cross-platform path is intentional — SSH paste types it into remote
terminals where ~/Library/Caches/ doesn't exist. Add a FAQ entry and
an inline comment explaining the invariant.

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: andyhtran

README.md

@@ -93,6 +93,10 @@ SSH paste has to use `~/` because the remote home dir is unknown. Your remote us
 
 Each screenshot is sent to every enabled host you've configured. With one host it's just SSH paste; with multiple it broadcasts (fans out) to all of them. Toggle individual hosts on/off in the menu bar to control which ones receive a given screenshot.
 
+**Why does CopyCat use `~/.cache/copycat/` instead of `~/Library/Caches/`?**
+
+So the same path resolves on both your Mac and remote Linux/NixOS hosts. SSH paste types `~/.cache/copycat/screenshot.jpg` into the terminal — that path needs to work on both sides without platform detection or separate configuration. The cache directory is configurable in Settings if you prefer a different location.
+
 **What's the simplest setup?**
 
 Leave SSH off. CopyCat then only intercepts ⌘V locally — no SSH, no remote hosts, no Tailscale needed. Turn SSH on when you want to paste into a remote shell.

Sources/CopyCat/Settings.swift

@@ -38,6 +38,10 @@ enum SettingsDefaults {
     static let broadcastHotkey: BroadcastHotkey = .cmdV
     static let cacheKeepCount = 50
 
+    // ~/.cache/copycat/ on all platforms, not ~/Library/Caches/ on macOS.
+    // SSH paste types this path into the terminal and it must resolve on
+    // both the local Mac and remote Linux hosts. A single cross-platform
+    // path keeps that invariant without platform detection or split config.
     static var cacheDir: URL {
         FileManager.default.homeDirectoryForCurrentUser
             .appendingPathComponent(".cache/copycat", isDirectory: true)