[BUG] Entire transcript replays verbatim (duplicated output) after window resize — classic renderer, Windows Terminal

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report
• [x] I am using the latest version of Claude Code (2.1.285)

Related but distinct: #83274 reports stale content lingering after a resize.
This report is about the entire transcript being re-emitted verbatim — duplicated
output, not stale output. Same trigger, different failure mode.

What's Wrong?

After manually resizing the Windows Terminal window once during a session, the next
redraw replays the entire transcript verbatim: every previously rendered line is
written a second time, appended below the original. The result is a duplicated /
overlapping view of the whole conversation.

This is reproducible on demand, not intermittent.

Steps to Reproduce

1. Windows Terminal (PowerShell profile), start claude — tui is default

(classic renderer), which is the default on Windows.

1. Send a message, get a reply.
2. While the second turn is streaming, drag the window edge.
3. Observe: the whole scrollback — from the startup banner through the previous

turn — is emitted again, verbatim, below the original.

Expected Behavior

Repaint in place. No duplicate emission.

Evidence

• Reproduced twice; the second time deliberately, by resizing mid-turn-2.
• The duplicated block begins at the status line and ends at the previous user

message; live output continues correctly after it.

• The startup banner is partially duplicated: the Claude Code v2.1.285 and

Sonnet 5 with xhigh effort lines appear twice, but the cwd line appears once
— i.e. the boundary falls between the renderer's on-screen rows and its
recorded history.

Root Cause (from the 2.1.285 bundle)

handleResize(cols, rows) explicitly requests a full replay:

handleResize(o,l){
  if(o===this.cols&&l===this.rows)return"noop";
  ...
  if(d||l<m)                                  // width changed, or height shrank
    return this.buf+=S5+X_+TXe+ey,            // clear/erase sequences
      this.buf+=Ure(1,Math.max(2,p)),
      this.resetTransientState(),
      this.replayPending=!0,                  // <- schedules a full replay
      this.pumpCursor=this.nativeHistory.length>0?0:-1,
      this.lastFrame="",
      this.commitImmediate(),
      "replay";
}

nativeHistory holds everything the classic renderer has committed to the
terminal's native scrollback. tickPump() then re-emits it from index 0.

The intent is "clear the screen, repaint at the new width". On Windows Terminal
this fails: the erase sequences are addressed to the renderer's accounted cursor
position (committedTop / pumpCursor), but Windows Terminal has already reflowed
the scrollback on resize, so the real cursor no longer matches. The erase lands in
the wrong place and the replayed content is appended instead of replacing the
original — hence verbatim duplication rather than a clean repaint.

Consistent with the Windows Terminal maintainer's assessment that resize issues
stem from applications' redraw handling (microsoft/terminal#14448).

Workaround

• /tui fullscreen — the alt-screen renderer does not maintain nativeHistory

and does not go through this path. Verified: the duplication is gone. Side
effect: the static Clawd banner art is not drawn.

• With the classic renderer: avoid resizing the window mid-session. Sizing the

window before starting avoids the trigger entirely.

Not a workaround

• Ctrl+L does nothing. In the Chat context, ctrl+l is bound to

chat:clearInput, and chat:clearScreen maps to the same handler. forceRedraw()
is only invoked internally (resize / stdout backpressure / programmatic prompt
change) — the classic renderer has no user-reachable full-repaint keybinding.

Environment

• Claude Code: 2.1.285
• OS: Windows 11 Home China, 10.0.26200
• Terminal: Windows Terminal (1.24.11911.0; 1.21.10351.0 also installed)
• Shell: PowerShell 5.1.26100.9278 (profile); also observed under pwsh 7.6.6
• tui: default (classic renderer)
• Terminal captured at 80x24