fix(mobile): add tap threshold to terminal touch handler

touchmove fires on any 1px finger drift, marking didScroll=true and
skipping the tap handler (which refocuses terminal/CJK input). On
iPad's large touch surface and phones with imprecise taps, this makes
terminal tap unreliable — cjkActive gets stuck true, blocking all
input (CJK and paste).

Add 8px TAP_THRESHOLD: finger movement under 8px is still a tap.
Also add touch-action:none on .touch-device .terminal-container
so the browser doesn't consume touch events before our JS handler.

src/web/public/input-cjk.js

@@ -162,6 +162,10 @@ const CjkInput = (() => {
         if (!_textarea.classList.contains('cjk-input-visible')) {
           window.cjkActive = false;
         }
+        // Reset composing state — some IMEs fire compositionstart without a
+        // matching compositionend, leaving _composing stuck true and blocking
+        // all subsequent input events.
+        _composing = false;
       };
       _textarea.addEventListener('mousedown', _listeners.mousedown);
       _textarea.addEventListener('focus', _listeners.focus);
@@ -214,8 +218,10 @@ const CjkInput = (() => {
           return;
         }
 
-        // Below: only when NOT composing (composing keystrokes belong to IME)
-        if (_composing) return;
+        // Below: only when NOT composing (composing keystrokes belong to IME).
+        // Also check isComposing/keyCode 229 — the first keydown of a CJK
+        // sequence arrives BEFORE compositionstart, so _composing is still false.
+        if (_composing || e.isComposing || e.keyCode === 229) return;
 
         // Backspace: forward to PTY when no real text in textarea
         if (e.key === 'Backspace' && _isEffectivelyEmpty()) {

src/web/public/styles.css

@@ -996,6 +996,12 @@ body {
   display: none !important;
 }
 
+/* Redraw terminal header button: hidden by default (opt-in via App Settings →
+   Display → "Header Displays"). Pure client-side toggle. */
+.btn-redraw-terminal--hidden {
+  display: none !important;
+}
+
 .btn-icon-header.btn-settings {
   width: 30px;
   height: 30px;
@@ -2229,8 +2235,10 @@ body.solo-mode .btn-lifecycle-log {
   background: transparent !important;
 }
 
-/* Touch devices: JS touch handler owns scroll/tap — prevent browser
-   from consuming touch events before touchmove preventDefault fires. */
+/* Touch devices: prevent browser from claiming the touch gesture before
+   our JS touchmove handler fires. Without this, the browser starts native
+   scrolling during the first few px of finger travel and ignores our
+   subsequent preventDefault() — breaking custom terminal scroll. */
 .touch-device .terminal-container,
 .touch-device .terminal-container .xterm,
 .touch-device .terminal-container .xterm-viewport,

src/web/public/terminal-ui.js

@@ -365,11 +365,14 @@ Object.assign(CodemanApp.prototype, {
       let pixelAccum = 0;
 
       let didScroll = false; // track whether touchmove fired (tap vs scroll)
+      let touchStartY = 0;
+      const TAP_THRESHOLD = 8; // px — ignore micro-drift to distinguish tap from scroll
       container.addEventListener(
         'touchstart',
         (ev) => {
           if (ev.touches.length === 1) {
             touchLastY = ev.touches[0].clientY;
+            touchStartY = touchLastY;
             velocity = 0;
             pixelAccum = 0;
             isTouching = true;
@@ -388,9 +391,15 @@ Object.assign(CodemanApp.prototype, {
         'touchmove',
         (ev) => {
           if (ev.touches.length === 1 && isTouching) {
-            ev.preventDefault();
-            didScroll = true;
             const touchY = ev.touches[0].clientY;
+            if (!didScroll && Math.abs(touchY - touchStartY) >= TAP_THRESHOLD) {
+              didScroll = true;
+            }
+            // Only preventDefault once it's a real scroll — preventing micro-drift
+            // touchmove kills click synthesis, which iOS needs to show the keyboard.
+            if (didScroll) {
+              ev.preventDefault();
+            }
             const delta = touchLastY - touchY; // positive = scroll down
             pixelAccum += delta;
             velocity = delta * 1.2;
@@ -410,19 +419,21 @@ Object.assign(CodemanApp.prototype, {
 
       container.addEventListener(
         'touchend',
-        () => {
+        (ev) => {
           isTouching = false;
           if (!scrollFrame && Math.abs(velocity) > 0.3) {
             scrollFrame = requestAnimationFrame(scrollLoop);
           }
-          // Tap (no scroll): refocus xterm's hidden textarea so keyboard input
-          // routes back to the terminal. Without this, a tap on the terminal area
-          // consumes the touch event but xterm's textarea never regains focus.
           if (!didScroll && this.terminal) {
             const cjkInput = document.getElementById('cjkInput');
             if (cjkInput?.classList.contains('cjk-input-visible')) {
               cjkInput.focus();
             } else {
+              // Don't synthesize mousedown — the browser does it naturally
+              // because we don't preventDefault() for taps (< TAP_THRESHOLD).
+              // touch-action:none blocks native scroll but NOT click synthesis.
+              // The browser's mousedown carries detail:1 + correct coordinates,
+              // so xterm's SelectionService._handleSingleClick picks it up.
               this._syncMobileHelperTextareaToCursor();
               this.terminal.focus();
             }