Merge pull request #47 from TeigenZhang/fix/mobile-cjk-input-and-layout

fix: mobile CJK input, terminal flicker, and layout overflow

src/web/public/app.js

@@ -886,6 +886,8 @@ class CodemanApp {
     // Server sends this after SSE backpressure clears — terminal data was dropped,
     // so reload the buffer to recover from any display corruption.
     if (!this.activeSessionId || !this.terminal) return;
+    // Skip if buffer load already in progress — avoids competing clear+rewrite cycles
+    if (this._isLoadingBuffer) return;
     try {
       const res = await fetch(`/api/sessions/${this.activeSessionId}/terminal?tail=${TERMINAL_TAIL_SIZE}`);
       const data = await res.json();
@@ -909,6 +911,12 @@ class CodemanApp {
 
   async _onSessionClearTerminal(data) {
     if (data.id === this.activeSessionId) {
+      // Skip if selectSession is already loading the buffer — clearTerminal arriving
+      // during buffer load would clear the terminal mid-write, causing visible flicker
+      // and a race between two concurrent chunkedTerminalWrite calls (especially on mobile
+      // where rAF is slower). selectSession will handle the final buffer state.
+      if (this._isLoadingBuffer) return;
+
       // Fetch buffer, clear terminal, write buffer, resize (no Ctrl+L needed)
       try {
         const res = await fetch(`/api/sessions/${data.id}/terminal`);
@@ -1299,6 +1307,16 @@ class CodemanApp {
     });
   }
 
+  /** Show/hide the CJK input textarea based on user setting or server override */
+  _updateCjkInputState() {
+    const cjkEl = document.getElementById('cjkInput');
+    if (!cjkEl) return;
+    const settings = this.loadAppSettingsFromStorage();
+    const showCjk = this._serverCjkOverride || settings.cjkInputEnabled || false;
+    cjkEl.style.display = showCjk ? 'block' : 'none';
+    if (!showCjk) window.cjkActive = false;
+  }
+
   handleInit(data) {
     // Clear the init fallback timer since we got data
     if (this._initFallbackTimer) {
@@ -1307,12 +1325,9 @@ class CodemanApp {
     }
     const gen = ++this._initGeneration;
 
-    // CJK input form: show/hide based on server env INPUT_CJK_FORM=ON
+    // CJK input form: controlled by user setting (with server env as override)
-    const cjkEl = document.getElementById('cjkInput');
+    this._serverCjkOverride = data.inputCjkForm || false;
-    if (cjkEl) {
+    this._updateCjkInputState();
-      cjkEl.style.display = data.inputCjkForm ? 'block' : 'none';
-      if (!data.inputCjkForm) window.cjkActive = false;
-    }
 
     // Update version displays (header and toolbar)
     if (data.version) {
@@ -1988,6 +2003,12 @@ class CodemanApp {
 
   async selectSession(sessionId) {
     if (this.activeSessionId === sessionId) return;
+    // Focus terminal SYNCHRONOUSLY before any await — iOS Safari only honors
+    // programmatic focus() within the user-gesture call stack (e.g. tab click).
+    // After the first await the gesture context is lost and focus() is silently
+    // ignored, leaving the keyboard unable to send input to the terminal.
+    if (this.terminal) this.terminal.focus();
+
     const _selStart = performance.now();
     const _selName = this.sessions.get(sessionId)?.name || sessionId.slice(0,8);
     _crashDiag.log(`SELECT: ${_selName}`);

src/web/public/index.html

@@ -871,6 +871,16 @@
                   <span class="slider"></span>
                 </label>
               </div>
+              <div class="settings-item settings-item-multiline" title="Show a dedicated input field below the terminal for CJK (Chinese/Japanese/Korean) IME composition. Recommended for mobile devices with Chinese input methods where xterm's native input handling may drop characters.">
+                <div class="settings-item-text">
+                  <span class="settings-item-label">CJK Input</span>
+                  <span class="settings-item-desc">Dedicated IME input field for CJK languages</span>
+                </div>
+                <label class="switch switch-sm">
+                  <input type="checkbox" id="appSettingsCjkInput">
+                  <span class="slider"></span>
+                </label>
+              </div>
 
               <!-- Header Displays Section -->
               <div class="settings-section-header">Header Displays</div>

src/web/public/input-cjk.js

@@ -3,10 +3,36 @@
  *
  * Always-visible textarea below the terminal (in index.html).
  * The browser handles IME composition natively — we just read
- * textarea.value on Enter and send it to PTY.
+ * textarea.value and send it to PTY.
  * While this textarea has focus, window.cjkActive = true blocks xterm's onData.
  * Arrow keys and function keys are forwarded to PTY directly.
  *
+ * ## Android IME challenge
+ *
+ * Android virtual keyboards (WeChat, Sogou, Gboard in Chinese mode) use
+ * composition for EVERYTHING — including English prediction and punctuation.
+ * This means compositionstart fires even for English text, and compositionend
+ * may not fire until the user explicitly confirms (space, candidate tap).
+ *
+ * We use InputEvent.inputType to distinguish:
+ * - `insertCompositionText`: tentative text, may change (CJK candidates, pinyin)
+ * - `insertText`: final committed text (confirmed word, punctuation, space)
+ *
+ * During composition, `insertText` events are flushed immediately (punctuation,
+ * English words confirmed by IME). `insertCompositionText` waits for
+ * compositionend (CJK candidate selection).
+ *
+ * ## Phantom character for Android backspace
+ *
+ * Android virtual keyboards don't generate key-repeat keydown events for held
+ * keys. When the textarea is empty, backspace produces no `input` event either
+ * (nothing to delete). We keep a zero-width space (U+200B) "phantom" in the
+ * textarea at all times. Backspace deletes the phantom → `input` fires with
+ * `deleteContentBackward` → we send \x7f to PTY and restore the phantom.
+ * Long-press backspace generates rapid deleteContentBackward events, each
+ * handled the same way — giving continuous deletion at the keyboard's native
+ * repeat rate.
+ *
  * @dependency index.html (#cjkInput textarea)
  * @globals {object} CjkInput — window.cjkActive (boolean) signals app.js to block xterm onData
  * @loadorder 5.5 of 15 — loaded after keyboard-accessory.js, before app.js
@@ -17,10 +43,12 @@ const CjkInput = (() => {
   let _textarea = null;
   let _send = null;
   let _initialized = false;
-  let _onMousedown = null;
+  let _composing = false;
-  let _onFocus = null;
+  const _listeners = {};
-  let _onBlur = null;
+
-  let _onKeydown = null;
+  // Zero-width space: always present in textarea so Android backspace has
+  // something to delete, triggering the `input` event we need to detect it.
+  const PHANTOM = '\u200B';
 
   const PASSTHROUGH_KEYS = {
     ArrowUp:    '\x1b[A',
@@ -36,66 +64,176 @@ const CjkInput = (() => {
     c: '\x03', d: '\x04', l: '\x0c', z: '\x1a', a: '\x01', e: '\x05',
   };
 
+  /** Strip phantom characters from a string */
+  function _strip(str) {
+    return str.replace(/\u200B/g, '');
+  }
+
+  /** Reset textarea to phantom-only state with cursor at end */
+  function _resetToPhantom() {
+    _textarea.value = PHANTOM;
+    _textarea.setSelectionRange(1, 1);
+  }
+
+  /** Check if textarea contains only phantom(s) or is empty — no real user text */
+  function _isEffectivelyEmpty() {
+    return !_strip(_textarea.value);
+  }
+
+  /** Flush textarea: send real text to PTY and reset to phantom */
+  function _flush() {
+    const val = _strip(_textarea.value);
+    if (val) {
+      _send(val);
+    }
+    _resetToPhantom();
+  }
+
   return {
     init({ send }) {
-      // Guard against double-init: remove previous listeners
       if (_initialized) this.destroy();
 
       _send = send;
+      _composing = false;
       _textarea = document.getElementById('cjkInput');
       if (!_textarea) return this;
 
-      _onMousedown = (e) => { e.stopPropagation(); };
+      // Seed the phantom character
-      _onFocus = () => { window.cjkActive = true; };
+      _resetToPhantom();
-      _onBlur = () => { window.cjkActive = false; };
-      _textarea.addEventListener('mousedown', _onMousedown);
-      _textarea.addEventListener('focus', _onFocus);
-      _textarea.addEventListener('blur', _onBlur);
 
-      _onKeydown = (e) => {
+      _listeners.mousedown = (e) => { e.stopPropagation(); };
-        if (e.isComposing || e.keyCode === 229) return;
+      _listeners.focus = () => {
+        window.cjkActive = true;
+        // Restore phantom if textarea was emptied while blurred
+        if (!_textarea.value) _resetToPhantom();
+      };
+      _listeners.blur = () => { window.cjkActive = false; };
+      _textarea.addEventListener('mousedown', _listeners.mousedown);
+      _textarea.addEventListener('focus', _listeners.focus);
+      _textarea.addEventListener('blur', _listeners.blur);
 
-        // Enter: send accumulated text (or bare Enter if empty)
+      // ── Composition tracking ──
+      _listeners.compositionstart = () => {
+        _composing = true;
+        // Clear phantom so IME sees a clean textarea — some IMEs include
+        // existing text in the composition region which would corrupt input.
+        if (_textarea.value === PHANTOM) {
+          _textarea.value = '';
+        }
+      };
+      _listeners.compositionend = () => {
+        _composing = false;
+        // Defer flush: some Android IMEs haven't committed text to textarea
+        // when compositionend fires. setTimeout(0) ensures we read the final value.
+        setTimeout(_flush, 0);
+      };
+      _textarea.addEventListener('compositionstart', _listeners.compositionstart);
+      _textarea.addEventListener('compositionend', _listeners.compositionend);
+
+      // ── Keydown: special keys work REGARDLESS of composition state ──
+      _listeners.keydown = (e) => {
+        // Enter: flush accumulated text (or bare Enter if empty).
+        // No isComposing guard — Android IMEs set isComposing=true for English
+        // prediction, but Enter should ALWAYS send. We preventDefault to stop
+        // the IME from also handling Enter (which could double-send or do nothing).
         if (e.key === 'Enter') {
           e.preventDefault();
-          if (_textarea.value) {
+          _composing = false;
-            _send(_textarea.value + '\r');
+          const val = _strip(_textarea.value);
-            _textarea.value = '';
+          if (val) {
+            _send(val + '\r');
           } else {
             _send('\r');
           }
+          _resetToPhantom();
           return;
         }
 
-        // Escape: clear textarea
+        // Escape: clear textarea (always works)
         if (e.key === 'Escape') {
           e.preventDefault();
-          _textarea.value = '';
+          _composing = false;
+          _resetToPhantom();
           return;
         }
 
-        // Ctrl combos: forward to PTY
+        // Ctrl combos: forward to PTY (always works)
         if (e.ctrlKey && CTRL_KEYS[e.key]) {
           e.preventDefault();
           _send(CTRL_KEYS[e.key]);
           return;
         }
 
-        // Backspace: delete from textarea if has text, else forward to PTY
+        // Below: only when NOT composing (composing keystrokes belong to IME)
-        if (e.key === 'Backspace' && !_textarea.value) {
+        if (_composing) return;
+
+        // Backspace: forward to PTY when no real text in textarea
+        // (Desktop path — Android uses the input event + phantom approach)
+        if (e.key === 'Backspace' && _isEffectivelyEmpty()) {
           e.preventDefault();
           _send('\x7f');
+          _resetToPhantom();
           return;
         }
 
-        // Arrow/function keys: forward to PTY when textarea is empty
+        // Arrow/function keys: forward to PTY when no real text
-        if (PASSTHROUGH_KEYS[e.key] && !_textarea.value) {
+        if (PASSTHROUGH_KEYS[e.key] && _isEffectivelyEmpty()) {
           e.preventDefault();
           _send(PASSTHROUGH_KEYS[e.key]);
           return;
         }
+
+        // Single printable character: send immediately to PTY
+        // (Desktop keyboards with physical keys — Android sends 'Unidentified')
+        if (e.key.length === 1 && !e.ctrlKey && !e.altKey && !e.metaKey && _isEffectivelyEmpty()) {
+          e.preventDefault();
+          _send(e.key);
+          return;
+        }
       };
-      _textarea.addEventListener('keydown', _onKeydown);
+      _textarea.addEventListener('keydown', _listeners.keydown);
+
+      // ── Input event: the primary path for Android virtual keyboards ──
+      // Android sends keyCode 229 + key "Unidentified" for virtual key presses,
+      // making keydown unreliable. input fires AFTER character insertion and
+      // carries inputType which tells us whether the text is final or tentative.
+      _listeners.input = (e) => {
+        // ── Backspace / delete detection ──
+        // Android long-press backspace generates rapid deleteContentBackward events.
+        // The phantom character ensures the textarea is never truly empty, so each
+        // press/repeat fires an input event that we can catch here.
+        if (e.inputType === 'deleteContentBackward' || e.inputType === 'deleteWordBackward') {
+          if (_isEffectivelyEmpty()) {
+            // No real text left — forward backspace to PTY
+            _send('\x7f');
+            _resetToPhantom();
+            return;
+          }
+          // User is editing their own text in the textarea — let it be.
+          // Ensure phantom is still present for the NEXT backspace.
+          if (!_textarea.value.startsWith(PHANTOM)) {
+            _textarea.value = PHANTOM + _textarea.value;
+            _textarea.setSelectionRange(1, 1);
+          }
+          return;
+        }
+
+        if (_composing) {
+          // insertText during composition = IME committed final text
+          // (e.g., punctuation key inserts 。directly, or IME confirms a word).
+          // Flush immediately — this text won't change.
+          if (e.inputType === 'insertText') {
+            _flush();
+            return;
+          }
+          // insertCompositionText = IME is still working (pinyin, candidates,
+          // English prediction). Wait for compositionend to flush.
+          return;
+        }
+        // Outside composition: send immediately
+        _flush();
+      };
+      _textarea.addEventListener('input', _listeners.input);
 
       _initialized = true;
       return this;
@@ -103,13 +241,13 @@ const CjkInput = (() => {
 
     destroy() {
       if (_textarea) {
-        if (_onMousedown) _textarea.removeEventListener('mousedown', _onMousedown);
+        for (const [event, handler] of Object.entries(_listeners)) {
-        if (_onFocus) _textarea.removeEventListener('focus', _onFocus);
+          if (handler) _textarea.removeEventListener(event, handler);
-        if (_onBlur) _textarea.removeEventListener('blur', _onBlur);
+        }
-        if (_onKeydown) _textarea.removeEventListener('keydown', _onKeydown);
       }
       window.cjkActive = false;
-      _onMousedown = _onFocus = _onBlur = _onKeydown = null;
+      _composing = false;
+      for (const key of Object.keys(_listeners)) delete _listeners[key];
       _initialized = false;
     },
 

src/web/public/mobile.css

@@ -1147,6 +1147,7 @@ html.mobile-init .file-browser-panel {
 
   /* Compact welcome overlay for mobile */
   .welcome-content {
+    max-width: calc(100vw - 1.5rem);
     padding: 1rem 0.75rem;
   }
 

src/web/public/session-ui.js

@@ -273,6 +273,11 @@ Object.assign(CodemanApp.prototype, {
     this.terminal.clear();
     this.terminal.writeln(`\x1b[1;32m Starting ${tabCount} Claude session(s) in ${caseName}...\x1b[0m`);
     this.terminal.writeln('');
+    // Focus terminal NOW, in the synchronous user-gesture context (button click).
+    // iOS Safari ignores programmatic focus() after any await, so this must happen
+    // before the first async call. The keyboard opens here and stays open through
+    // the session creation flow; selectSession at the end inherits the focus state.
+    this.terminal.focus();
 
     try {
       // Get case path first
@@ -493,6 +498,8 @@ Object.assign(CodemanApp.prototype, {
     this.terminal.clear();
     this.terminal.writeln(`\x1b[1;32m Starting OpenCode session in ${caseName}...\x1b[0m`);
     this.terminal.writeln('');
+    // Focus in sync gesture context (see runClaude comment)
+    this.terminal.focus();
 
     try {
       // Check if OpenCode is available

src/web/public/settings-ui.js

@@ -364,6 +364,7 @@ Object.assign(CodemanApp.prototype, {
     document.getElementById('appSettingsTunnelEnabled').checked = settings.tunnelEnabled ?? false;
     this.loadTunnelStatus();
     document.getElementById('appSettingsLocalEcho').checked = settings.localEchoEnabled ?? MobileDetection.isTouchDevice();
+    document.getElementById('appSettingsCjkInput').checked = settings.cjkInputEnabled ?? false;
     document.getElementById('appSettingsTabTwoRows').checked = settings.tabTwoRows ?? defaults.tabTwoRows ?? false;
     // Claude CLI settings
     const claudeModeSelect = document.getElementById('appSettingsClaudeMode');
@@ -1180,6 +1181,7 @@ Object.assign(CodemanApp.prototype, {
       imageWatcherEnabled: document.getElementById('appSettingsImageWatcherEnabled').checked,
       tunnelEnabled: document.getElementById('appSettingsTunnelEnabled').checked,
       localEchoEnabled: document.getElementById('appSettingsLocalEcho').checked,
+      cjkInputEnabled: document.getElementById('appSettingsCjkInput').checked,
       tabTwoRows: document.getElementById('appSettingsTabTwoRows').checked,
       // Claude CLI settings
       claudeMode: document.getElementById('appSettingsClaudeMode').value,
@@ -1296,9 +1298,12 @@ Object.assign(CodemanApp.prototype, {
     this.renderProjectInsightsPanel();  // Re-render to apply visibility setting
     this.updateSubagentWindowVisibility();  // Apply subagent window visibility setting
 
+    // Apply CJK input visibility immediately
+    this._updateCjkInputState();
+
     // Save to server (includes notification prefs for cross-browser persistence)
-    // Strip device-specific keys — localEchoEnabled is per-platform (touch default differs)
+    // Strip device-specific keys — localEchoEnabled/cjkInputEnabled are per-platform
-    const { localEchoEnabled: _leo, ...serverSettings } = settings;
+    const { localEchoEnabled: _leo, cjkInputEnabled: _cjk, ...serverSettings } = settings;
     try {
       await this._apiPut('/api/settings', { ...serverSettings, notificationPreferences: notifPrefsToSave, voiceSettings });
 
@@ -1682,7 +1687,7 @@ Object.assign(CodemanApp.prototype, {
         const displayKeys = new Set([
           'showFontControls', 'showSystemStats', 'showTokenCount', 'showCost',
           'showMonitor', 'showProjectInsights', 'showFileBrowser', 'showSubagents',
-          'subagentActiveTabOnly', 'tabTwoRows', 'localEchoEnabled',
+          'subagentActiveTabOnly', 'tabTwoRows', 'localEchoEnabled', 'cjkInputEnabled',
         ]);
         // Merge settings: non-display keys always sync from server,
         // display keys only seed from server when localStorage has no value

src/web/public/styles.css

@@ -94,7 +94,11 @@ textarea:focus-visible {
   outline: none;
 }
 
-/* xterm.js hidden textarea — must never show focus ring or caret */
+/* xterm.js hidden textarea — must never show focus ring or caret.
+ * On mobile (touch devices), override xterm.css defaults that position the
+ * textarea at left:-9999em with width/height:0. iOS Safari ignores keyboard
+ * input to off-screen zero-size textareas, so we move it on-screen with a
+ * minimal size while keeping it visually invisible. */
 .xterm-helper-textarea {
   border: none !important;
   box-shadow: none !important;
@@ -102,6 +106,14 @@ textarea:focus-visible {
   opacity: 0 !important;
   caret-color: transparent !important;
 }
+.touch-device .xterm .xterm-helper-textarea {
+  left: 0 !important;
+  top: 0 !important;
+  width: 1px !important;
+  height: 1px !important;
+  z-index: -1 !important;
+  font-size: 16px !important; /* prevent iOS auto-zoom on focus */
+}
 
 /* Session tab focus */
 .session-tab:focus-visible {

src/web/public/terminal-ui.js

@@ -174,12 +174,14 @@ Object.assign(CodemanApp.prototype, {
       // Accumulate sub-line pixel deltas so slow swipes still scroll
       let pixelAccum = 0;
 
+      let didScroll = false; // track whether touchmove fired (tap vs scroll)
       container.addEventListener('touchstart', (ev) => {
         if (ev.touches.length === 1) {
           touchLastY = ev.touches[0].clientY;
           velocity = 0;
           pixelAccum = 0;
           isTouching = true;
+          didScroll = false;
           lastTime = 0;
           if (scrollFrame) { cancelAnimationFrame(scrollFrame); scrollFrame = null; }
         }
@@ -187,6 +189,7 @@ Object.assign(CodemanApp.prototype, {
 
       container.addEventListener('touchmove', (ev) => {
         if (ev.touches.length === 1 && isTouching) {
+          didScroll = true;
           const touchY = ev.touches[0].clientY;
           const delta = touchLastY - touchY; // positive = scroll down
           pixelAccum += delta;
@@ -207,6 +210,12 @@ Object.assign(CodemanApp.prototype, {
         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) {
+          this.terminal.focus();
+        }
       }, { passive: true });
 
       container.addEventListener('touchcancel', () => {
@@ -260,17 +269,6 @@ Object.assign(CodemanApp.prototype, {
           }
           this.flushFlickerBuffer();
         }
-        // Clear viewport + scrollback for Ink-based sessions before sending SIGWINCH.
-        // fitAddon.fit() reflows content: lines at old width may wrap to more rows,
-        // pushing overflow into scrollback. Ink's cursor-up count is based on the
-        // pre-reflow line count, so ghost renders accumulate in scrollback.
-        // Fix: \x1b[3J (Erase Saved Lines) clears scrollback reflow debris,
-        // then \x1b[H\x1b[2J clears the viewport for a clean Ink redraw.
-        const activeResizeSession = this.activeSessionId ? this.sessions.get(this.activeSessionId) : null;
-        if (activeResizeSession && activeResizeSession.mode !== 'shell' && !activeResizeSession._ended
-            && this.terminal && this.isTerminalAtBottom()) {
-          this.terminal.write('\x1b[3J\x1b[H\x1b[2J');
-        }
         // Skip server resize while mobile keyboard is visible — sending SIGWINCH
         // causes Ink to re-render at the new row count, garbling terminal output.
         // Local fit() still runs so xterm knows the viewport size for scrolling.
@@ -284,6 +282,19 @@ Object.assign(CodemanApp.prototype, {
           if (!this._lastResizeDims ||
               cols !== this._lastResizeDims.cols ||
               rows !== this._lastResizeDims.rows) {
+            // Clear viewport + scrollback ONLY when dimensions actually change.
+            // fitAddon.fit() reflows content: lines at old width may wrap to more rows,
+            // pushing overflow into scrollback. Ink's cursor-up count is based on the
+            // pre-reflow line count, so ghost renders accumulate in scrollback.
+            // Fix: \x1b[3J (Erase Saved Lines) clears scrollback reflow debris,
+            // then \x1b[H\x1b[2J clears the viewport for a clean Ink redraw.
+            // IMPORTANT: Only clear when we're actually sending SIGWINCH (dims changed).
+            // Clearing without a subsequent Ink redraw leaves the terminal blank.
+            const activeResizeSession = this.activeSessionId ? this.sessions.get(this.activeSessionId) : null;
+            if (activeResizeSession && activeResizeSession.mode !== 'shell' && !activeResizeSession._ended
+                && this.terminal && this.isTerminalAtBottom()) {
+              this.terminal.write('\x1b[3J\x1b[H\x1b[2J');
+            }
             this._lastResizeDims = { cols, rows };
             fetch(`/api/sessions/${this.activeSessionId}/resize`, {
               method: 'POST',
@@ -1261,6 +1272,10 @@ Object.assign(CodemanApp.prototype, {
     if (this.fitAddon) this.fitAddon.fit();
     const dims = this.getTerminalDimensions();
     if (!dims) return;
+    // Update _lastResizeDims so the throttledResize handler won't redundantly
+    // clear the terminal for the same dimensions (which would blank the screen
+    // without a subsequent Ink redraw to repaint it).
+    this._lastResizeDims = { cols: dims.cols, rows: dims.rows };
     // Fast path: WebSocket resize
     if (this._wsReady && this._wsSessionId === sessionId) {
       try {