Add doc comments

rust/tauri-pinch-zoom.md

@@ -18,12 +18,19 @@ the cursor position.
 ```toml
 # src-tauri/Cargo.toml
 
-``[target."cfg(target_os = \"linux\")".dependencies]
+[target."cfg(target_os = \"linux\")".dependencies]
 gtk = "0.18.2"
 ```
 
 ```rust
-``#[cfg(target_os = "linux")]
+// src-tauri/src/lib.rs
+
+/// On Linux, Tauri's WebKitGTK webview intercepts trackpad pinch as page zoom
+/// before JS sees it. This attaches a GTK gesture controller that captures the
+/// pinch in the `Capture` phase and claims it (preventing WebKit from also
+/// handling it), then emits Tauri events that the frontend re-dispatches as
+/// synthetic Ctrl+wheel events.
+#[cfg(target_os = "linux")]
 fn setup_linux_pinch(window: &tauri::WebviewWindow) {
     use gtk::prelude::*;
     use gtk::{EventSequenceState, PropagationPhase};
@@ -80,6 +87,12 @@ fail to initialize.
 ```ts
 // src/tauriPinchAdapter.ts
 
+/**
+ * On Linux, Tauri's WebKitGTK webview intercepts trackpad pinch as page zoom
+ * before JS sees it. The Rust side captures the gesture and emits Tauri events;
+ * this adapter re-dispatches them as synthetic Ctrl+wheel events so frontend
+ * code can handle pinch the same way browsers natively report it.
+ */
 export async function setupTauriPinchAdapter() {
     // Bail out if not running inside Tauri
     if (typeof window === 'undefined' || !('__TAURI_INTERNALS__' in window)) {