Merge master (PR #112 terminal pane-buffer rework) into v1-readiness-hardening

Conflict in src/web/public/app.js selectSession: combined #112's
_clearTerminalLoadState cleanup on stale select with #113's
{success,data} envelope unwrap of the terminal fetch.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/web/public/terminal-ui.js

@@ -12,6 +12,24 @@
  * @loadorder 7 of 15 — loaded after app.js, before respawn-ui.js
  */
 
+(function (global) {
+  const TERMINAL_QUERY_RESPONSE_PATTERN = /^\x1b\[[\?>=]?[\d;]*[cnR]$/;
+  const TERMINAL_OSC_RESPONSE_PATTERN = /^\x1b\][\d;]*[^\x07\x1b]*(?:\x07|\x1b\\)$/;
+
+  function isTerminalQueryResponse(data) {
+    return TERMINAL_QUERY_RESPONSE_PATTERN.test(data) || TERMINAL_OSC_RESPONSE_PATTERN.test(data);
+  }
+
+  function shouldSuppressTerminalQueryResponse(data) {
+    return isTerminalQueryResponse(data);
+  }
+
+  global.CodemanTerminalInput = {
+    isTerminalQueryResponse,
+    shouldSuppressTerminalQueryResponse,
+  };
+})(window);
+
 Object.assign(CodemanApp.prototype, {
   // ═══════════════════════════════════════════════════════════════
   // Terminal Setup — xterm.js config and input handling
@@ -164,7 +182,24 @@ Object.assign(CodemanApp.prototype, {
           // whitespace) -- if so, xterm handled it and we should not double-send.
           // Use a microtask to check after xterm's own handlers have run.
           const data = e.data;
+          const pendingBefore = this._localEchoOverlay?.pendingText || '';
           Promise.resolve().then(() => {
+            if (
+              this._lastTerminalData?.data === data &&
+              performance.now() - this._lastTerminalData.time < 100
+            ) {
+              xtermTextarea.value = '';
+              return;
+            }
+            const pendingAfter = this._localEchoOverlay?.pendingText || '';
+            if (
+              this._localEchoEnabled &&
+              pendingAfter.length > pendingBefore.length &&
+              pendingAfter.endsWith(data)
+            ) {
+              xtermTextarea.value = '';
+              return;
+            }
             // If xterm cleared the textarea, it processed the input -- skip.
             const val = xtermTextarea.value;
             if (!val || (val.trim() === '' && data !== ' ')) return;
@@ -328,6 +363,7 @@ Object.assign(CodemanApp.prototype, {
         'touchmove',
         (ev) => {
           if (ev.touches.length === 1 && isTouching) {
+            ev.preventDefault();
             didScroll = true;
             const touchY = ev.touches[0].clientY;
             const delta = touchLastY - touchY; // positive = scroll down
@@ -343,7 +379,7 @@ Object.assign(CodemanApp.prototype, {
             }
           }
         },
-        { passive: true }
+        { passive: false }
       );
 
       container.addEventListener(
@@ -382,6 +418,8 @@ Object.assign(CodemanApp.prototype, {
 
     // Generation counter for chunkedTerminalWrite — aborts stale writes on tab switch
     this._chunkedWriteGen = 0;
+    this._bufferLoadSeq = 0;
+    this._bufferLoadOwner = null;
 
     // Handle resize with throttling for performance
     this._resizeTimeout = null;
@@ -498,11 +536,15 @@ Object.assign(CodemanApp.prototype, {
       // CJK input has focus — block xterm from sending to PTY
       if (window.cjkActive || document.activeElement?.id === 'cjkInput') return;
       if (this.activeSessionId) {
-        // Filter out terminal query responses that xterm.js generates automatically.
-        // These are responses to DA (Device Attributes), DSR (Device Status Report), etc.
-        // sent by tmux when attaching. Without this filter, they appear as typed text.
-        // Patterns: \x1b[?...c (DA1), \x1b[>...c (DA2), \x1b[...R (CPR), \x1b[...n (DSR)
-        if (/^\x1b\[[\?>=]?[\d;]*[cnR]$/.test(data)) return;
+        // Filter terminal query replies generated by xterm.js itself.
+        // Forwarding them through the WebSocket injects DA/DSR/CPR replies
+        // into the foreground process as typed input (for example "0;276;0c").
+        if (
+          window.CodemanTerminalInput?.shouldSuppressTerminalQueryResponse(data)
+        ) {
+          return;
+        }
+        this._lastTerminalData = { data, time: performance.now() };
 
         // ── Local Echo Mode ──
         // When enabled, keystrokes are buffered locally in the overlay for
@@ -1594,6 +1636,38 @@ Object.assign(CodemanApp.prototype, {
     }
   },
 
+  scrollToLastNonEmptyLine() {
+    if (!this.terminal?.buffer?.active) {
+      this.terminal?.scrollToBottom?.();
+      return;
+    }
+
+    const buffer = this.terminal.buffer.active;
+    const totalLines = buffer.baseY + buffer.length;
+    let lastNonEmptyLine = -1;
+
+    for (let lineIndex = totalLines - 1; lineIndex >= 0; lineIndex--) {
+      const line = buffer.getLine(lineIndex);
+      if (line?.translateToString(true).trim()) {
+        lastNonEmptyLine = lineIndex;
+        break;
+      }
+    }
+
+    if (lastNonEmptyLine >= 0 && typeof this.terminal.scrollToLine === 'function') {
+      let targetLine = Math.max(0, lastNonEmptyLine - this.terminal.rows + 2);
+      const maxTargetLine = Math.max(0, lastNonEmptyLine);
+      while (targetLine < maxTargetLine) {
+        const line = buffer.getLine(targetLine);
+        if (line?.translateToString(true).trim()) break;
+        targetLine++;
+      }
+      this.terminal.scrollToLine(targetLine);
+    } else {
+      this.terminal.scrollToBottom();
+    }
+  },
+
   /**
    * Write large buffer to terminal in chunks to avoid UI jank.
    * Uses _safeYield to spread work across frames; falls back to setTimeout
@@ -1602,22 +1676,19 @@ Object.assign(CodemanApp.prototype, {
    * @param {number} chunkSize - Size of each chunk (default 128KB for smooth 60fps)
    * @returns {Promise<void>} - Resolves when all chunks written
    */
-  chunkedTerminalWrite(buffer, chunkSize = TERMINAL_CHUNK_SIZE) {
+  chunkedTerminalWrite(buffer, chunkSize = TERMINAL_CHUNK_SIZE, loadOwner) {
     // Generation counter: if a newer chunkedTerminalWrite starts (tab switch),
     // older writes abort instead of continuing to push stale data into the terminal.
     const writeGen = ++this._chunkedWriteGen;
+    const bufferLoadOwner = this._beginBufferLoad(loadOwner);
 
     return new Promise((resolve) => {
       if (!buffer || buffer.length === 0) {
-        this._finishBufferLoad();
+        this._finishBufferLoad(bufferLoadOwner);
         resolve();
         return;
       }
 
-      // Block live SSE writes during buffer load to prevent interleaving
-      this._isLoadingBuffer = true;
-      this._loadBufferQueue = [];
-
       // Strip any DEC 2026 markers that might be in the buffer
       // (from historical SSE data that was stored with markers)
       const cleanBuffer = buffer.replace(DEC_SYNC_STRIP_RE, '');
@@ -1625,15 +1696,14 @@ Object.assign(CodemanApp.prototype, {
       const finish = () => {
         // Only finish if we're still the active write — a newer write owns buffer load state
         if (this._chunkedWriteGen === writeGen) {
-          this._finishBufferLoad();
+          this._finishBufferLoad(bufferLoadOwner);
         }
         resolve();
       };
 
       // For small buffers, write directly — single-frame render is fast enough
       if (cleanBuffer.length <= chunkSize) {
-        this.terminal.write(cleanBuffer);
-        finish();
+        this.terminal.write(cleanBuffer, finish);
         return;
       }
 
@@ -1691,9 +1761,23 @@ Object.assign(CodemanApp.prototype, {
    * (especially Ink cursor-up redraws), corrupting the terminal display.
    * After unblocking, new SSE/WS events deliver subsequent output normally.
    */
-  _finishBufferLoad() {
+  _beginBufferLoad(owner) {
+    if (this._bufferLoadSeq === undefined) this._bufferLoadSeq = 0;
+    const loadOwner = owner === undefined ? `buffer-${++this._bufferLoadSeq}` : owner;
+    this._bufferLoadOwner = loadOwner;
+    this._isLoadingBuffer = true;
+    this._loadBufferQueue = [];
+    return loadOwner;
+  },
+
+  _finishBufferLoad(owner) {
+    if (owner !== undefined && this._bufferLoadOwner !== owner) {
+      return false;
+    }
     this._isLoadingBuffer = false;
     this._loadBufferQueue = null;
+    this._bufferLoadOwner = null;
+    return true;
   },
 
   // ═══════════════════════════════════════════════════════════════
@@ -1814,23 +1898,30 @@ Object.assign(CodemanApp.prototype, {
   /**
    * Send resize to a session with minimum dimension enforcement.
    * @param {string} sessionId
+   * @param {{ forceHttp?: boolean }} [options]
    * @returns {Promise<void>}
    */
-  async sendResize(sessionId) {
+  async sendResize(sessionId, options = {}) {
     // Fit terminal to container before reading dimensions — ensures local
     // terminal size matches what we report to the server PTY.
     if (this.fitAddon) this.fitAddon.fit();
     const dims = this.getTerminalDimensions();
-    if (!dims) return;
+    if (!dims) return false;
+    // Did the dimensions actually change since the last resize we sent? Callers
+    // use this to skip work (e.g. the post-resize TUI-redraw settle) when no
+    // real SIGWINCH was triggered — switching tabs at the same browser size is
+    // a no-op on the server and needs no redraw grace.
+    const prev = this._lastResizeDims;
+    const changed = !prev || prev.cols !== dims.cols || prev.rows !== dims.rows;
     // 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) {
+    if (!options.forceHttp && this._wsReady && this._wsSessionId === sessionId) {
       try {
         this._ws.send(JSON.stringify({ t: 'z', c: dims.cols, r: dims.rows }));
-        return;
+        return changed;
       } catch {
         // Fall through to HTTP POST
       }
@@ -1840,6 +1931,7 @@ Object.assign(CodemanApp.prototype, {
       headers: { 'Content-Type': 'application/json' },
       body: JSON.stringify(dims),
     });
+    return changed;
   },
 
   /**