Initial commit — CTile Cinnamon extension

Snap layout overlay for Cinnamon 6.6. Drag a window to the top edge
to reveal a picker with 14 tiling presets (halves, quarters, thirds).
Layout previews use the system theme's accent color and update live
when the theme changes.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

README.md

@@ -0,0 +1,81 @@
+# CTile
+
+A Cinnamon desktop extension that brings snap layout overlays to window management — drag any window toward the top of your screen and a layout picker appears, letting you tile it into a preset zone without touching the keyboard.
+
+## How it works
+
+1. Start dragging any window by its titlebar
+2. Move the cursor within ~50px of the top screen edge — the layout picker appears
+3. Hover over the desired zone (the overlay stays visible as long as your cursor is within 20px of it)
+4. Release — the window snaps to that zone
+
+The overlay displays 14 layout presets across three rows:
+
+| Row | Layouts |
+|-----|---------|
+| Basic | Full, Left ½, Right ½, Top ½, Bottom ½ |
+| Quarters | Top-left, Top-right, Bottom-left, Bottom-right |
+| Thirds | Left ⅓, Center ⅓, Right ⅓, Left ⅔, Right ⅔ |
+
+Layout previews are drawn in your system theme's accent color and update automatically when you change themes.
+
+## Installation
+
+Copy (or symlink) the repo directory to Cinnamon's extensions folder under the extension's UUID, then enable it:
+
+```bash
+cp -r /path/to/ctile ~/.local/share/cinnamon/extensions/ctile@ctile
+```
+
+Then open **System Settings → Extensions**, find **CTile**, and enable it. Or via the command line:
+
+```bash
+gsettings set org.cinnamon enabled-extensions "['ctile@ctile']"
+```
+
+Restart Cinnamon (`Alt+F2` → `r` → Enter) if the extension doesn't appear immediately.
+
+## Development
+
+After editing, sync and reload without restarting Cinnamon:
+
+```bash
+cp extension.js stylesheet.css metadata.json ~/.local/share/cinnamon/extensions/ctile@ctile/
+```
+
+Then reload via Looking Glass (`Alt+F2` → `lg`) or with:
+
+```bash
+dbus-send --session --dest=org.Cinnamon /org/Cinnamon org.Cinnamon.Eval \
+  string:'const es = imports.ui.extensionSystem; es.disableExtension("ctile@ctile"); es.enableExtension("ctile@ctile");'
+```
+
+Debug output goes to `~/.xsession-errors` — search for `[ctile]`.
+
+## Tunables
+
+At the top of [extension.js](extension.js):
+
+| Constant | Default | Description |
+|----------|---------|-------------|
+| `TRIGGER_Y` | `50` | Pixels from top edge that triggers the overlay |
+| `POLL_INTERVAL` | `40` | Milliseconds between pointer polls during a drag |
+| `THUMB_W` / `THUMB_H` | `66` / `44` | Layout preview thumbnail dimensions |
+| `SHOW_ANIM_MS` / `HIDE_ANIM_MS` | `120` / `100` | Fade in/out duration |
+
+## Compatibility
+
+Tested on **Cinnamon 6.6.7** / **Muffin 6.6.3**.
+
+> **Note for porters:** Muffin 6.6 passes four arguments to `grab-op-begin` — `(display, screen, window, op)` — unlike older versions which passed three. If you see the overlay never appearing, verify the signal arity with Looking Glass.
+
+## File structure
+
+```
+ctile/
+├── extension.js    — all extension logic (~460 lines)
+├── metadata.json   — UUID, name, supported Cinnamon versions
+├── stylesheet.css  — overlay and button styles
+├── README.md
+└── AGENTS.md
+```