Merge pull request #116 from aakhter/pr/cod-35-codex-polish

fix(codex): strip alt-screen + scrollback-erase from the codex byte stream

src/session.ts

@@ -259,6 +259,9 @@ export class Session extends EventEmitter {
   private _messages: ClaudeMessage[] = [];
   private _lineBuffer: string = '';
   private _lineBufferFlushTimer: NodeJS.Timeout | null = null;
+  // Codex only: trailing partial CSI held back so sequences split across PTY
+  // chunks can't slip past the alt-screen/scrollback strip (see _handleTerminalOutput)
+  private _codexSeqCarry: string = '';
   private resolvePromise: ((value: { result: string; cost: number }) => void) | null = null;
   private rejectPromise: ((reason: Error) => void) | null = null;
   private _promptResolved: boolean = false; // Guard against race conditions in runPrompt
@@ -1091,6 +1094,47 @@ export class Session extends EventEmitter {
   }
 
   private _handleTerminalOutput(data: string): void {
+    // Codex emits sequences that wipe xterm.js scrollback, plus mouse-tracking
+    // enables that hijack the scroll wheel so the user can't reach scrollback:
+    //   - \x1b[?1049h / \x1b[?47h / \x1b[?1047h: switch to the alt buffer (no
+    //     scrollback) — \x1b[?...l switches back.
+    //   - \x1b[3J: erase saved lines (scrollback). (\x1b[2J / \x1b[J — erase
+    //     the visible viewport — are left intact; the TUI repaints those rows.)
+    //   - \x1b[?1000h / 1002h / 1003h / 1005h / 1006h / 1007h: mouse-tracking
+    //     modes (X10, button-event, any-event, UTF-8, SGR, alt-scroll). Once on,
+    //     xterm.js forwards wheel events to codex instead of scrolling the
+    //     viewport, so the conversation is in scrollback but unreachable.
+    //     (Focus events at ?1004 are left alone — codeman uses them for
+    //     active-tab detection.)
+    // Strip them at the source so neither the persisted buffer nor the live
+    // SSE/WS stream carries them, keeping everything in the main buffer with
+    // scrollback intact. Codex's cursor-positioned redraws overwrite only the
+    // cells they actually target, so the non-erased rows keep their content.
+    if (this.mode === 'codex') {
+      // Reassemble sequences split across PTY chunk boundaries first: a chunk
+      // ending mid-sequence ('\x1b[?104' now, '9h' next) would slip past the
+      // strip below and leave xterm stuck in the scrollback-less alt buffer
+      // until the next buffer replay. Hold back an incomplete digit-only CSI
+      // tail (≤7 chars — the longest strippable intro is '\x1b[?1049') and
+      // prepend it to the next chunk; complete sequences are never held.
+      data = this._codexSeqCarry + data;
+      this._codexSeqCarry = '';
+      // eslint-disable-next-line no-control-regex
+      const splitTail = data.match(/\x1b(?:\[\??[0-9]{0,4})?$/);
+      if (splitTail) {
+        this._codexSeqCarry = splitTail[0];
+        data = data.slice(0, -splitTail[0].length);
+        if (!data) return;
+      }
+      data = data
+        // eslint-disable-next-line no-control-regex
+        .replace(/\x1b\[\?(?:47|1047|1049)[hl]/g, '')
+        // eslint-disable-next-line no-control-regex
+        .replace(/\x1b\[3J/g, '')
+        // eslint-disable-next-line no-control-regex
+        .replace(/\x1b\[\?(?:1000|1001|1002|1003|1005|1006|1007)[hl]/g, '');
+    }
+
     // BufferAccumulator handles auto-trimming when max size exceeded
     this._terminalBuffer.append(data);
     this._lastActivityAt = Date.now();
@@ -1711,6 +1755,7 @@ export class Session extends EventEmitter {
     this._errorBuffer = '';
     this._messages = [];
     this._lineBuffer = '';
+    this._codexSeqCarry = '';
     this._lastActivityAt = Date.now();
   }
 

src/web/routes/session-routes.ts

@@ -66,6 +66,31 @@ const CLAUDE_BANNER_PATTERN = /\x1b\[1mClaud/;
 const CTRL_L_PATTERN = /\x0c/g;
 const LEADING_WHITESPACE_PATTERN = /^[\s\r\n]+/;
 
+/**
+ * Match xterm alternate-screen mode toggles + the standalone scrollback-erase.
+ *
+ * - DECSET/DECRST 47, 1047, 1049 = enter/exit alternate screen buffer
+ *   (1049 also saves cursor and clears the alt buffer).
+ * - CSI 3 J = erase saved lines (scrollback).
+ *
+ * Codex emits `\x1b[?1049h` and clear-scrollback sequences during startup and
+ * on repaint. xterm.js obeys them by switching to the alt buffer (no native
+ * scrollback) and wiping saved lines, so the user's conversation history
+ * disappears on every tab switch / pane refresh. Stripping these from the
+ * replayed byte stream keeps everything in the main buffer with scrollback
+ * intact. Mirrors the live-stream strip in Session._handleTerminalOutput.
+ */
+// eslint-disable-next-line no-control-regex
+const ALT_SCREEN_TOGGLE_PATTERN = /\x1b\[\?(?:47|1047|1049)[hl]/g;
+// eslint-disable-next-line no-control-regex
+const ERASE_SCROLLBACK_PATTERN = /\x1b\[3J/g;
+// Mouse-tracking enables (X10/button/any-event/UTF-8/SGR/alt-scroll) — once on,
+// xterm.js forwards wheel events to the app instead of scrolling the viewport.
+// Live streams are stripped at the source, but buffers persisted BEFORE that
+// strip existed can still carry them; strip on replay for parity.
+// eslint-disable-next-line no-control-regex
+const MOUSE_TRACKING_PATTERN = /\x1b\[\?(?:1000|1001|1002|1003|1005|1006|1007)[hl]/g;
+
 /**
  * Strip redundant Ink spinner/status-bar redraw frames from the terminal buffer.
  * Ink (Claude Code's TUI) uses absolute cursor positioning (CSI n d = VPA) to animate
@@ -917,7 +942,17 @@ export function registerSessionRoutes(
     // During long thinking phases, Ink rewrites the same rows thousands of times
     // (500KB+). Without stripping, tail mode returns only spinner frames and
     // the terminal appears empty when switching tabs.
-    const strippedBuffer = stripInkRedrawBloat(rawBuffer);
+    let strippedBuffer = stripInkRedrawBloat(rawBuffer);
+
+    // Strip alt-screen toggles and scrollback-erase from codex byte streams.
+    // xterm.js obeys them by switching to its scrollback-less alt buffer and
+    // wiping saved lines, so conversation history disappears on tab switch.
+    if (session.mode === 'codex') {
+      strippedBuffer = strippedBuffer
+        .replace(ALT_SCREEN_TOGGLE_PATTERN, '')
+        .replace(ERASE_SCROLLBACK_PATTERN, '')
+        .replace(MOUSE_TRACKING_PATTERN, '');
+    }
 
     if (tailBytes > 0 && strippedBuffer.length > tailBytes) {
       // Fast path: tail from the end, skip expensive banner search on full 2MB buffer.