Can't scroll back through terminal history on macOS trackpad (Claude sessions, 1.3.0) #154

Environment

• Codeman: 1.3.0 (self-hosted, git install)
• Claude Code CLI: 2.1.204
• Browser: Chrome on macOS (desktop)
• Input device: MacBook trackpad — no external mouse tested (see caveat below)

Problem

In a Claude session I can no longer scroll back through the terminal output. Scrolling up with a two-finger swipe only reaches roughly one screen (~34–36 lines); as new output arrives, older lines disappear and I can't scroll back to them. This used to work normally around 1.2.x — a plain two-finger scroll reached the terminal's scrollback.

Caveat: I use a MacBook trackpad and have not tested with a physical mouse wheel, so I can't confirm whether Shift+wheel behaves differently there. This report is specifically about the trackpad experience.

Steps to reproduce

1. Open a Claude session in the web UI on macOS/Chrome with a trackpad.
2. Produce more output than fits on screen (e.g. ask Claude to print 1–50).
3. Two-finger scroll up.

Expected: reach the top of the output (line 1).
Actual: only reach ~line 34–36; earlier lines are gone and can't be scrolled back to.

What I found while digging (may help narrow it down)

• I captured ~54 KB of the live PTY stream from a Claude session. It is entirely full-frame repaints: synchronized-update markers (CSI ?2026h/l, ~2130 of them) and absolute cursor addressing (CSI <row>;<col>H, ~2130), with 0 newlines in the whole stream. So Claude Code (≥ 2.1.187) repaints the viewport in place and never scrolls output into the terminal's scrollback. tmux confirms the pane is in the alternate screen with history_size=0.
• _shouldForwardWheelToApp (from feat(web): restore tap/click/wheel mouse interaction when server strips mouse DECSETs #144) forwards the plain wheel to the CLI for claude ≥ 2.1.187 (so Claude scrolls its own transcript), and moves the local xterm scrollback onto Shift+wheel.
• On a macOS trackpad, holding Shift while two-finger scrolling is interpreted by the browser as horizontal scroll (deltaY ≈ 0), so the Shift+wheel branch of the container wheel handler never fires. Combined with the point above, there doesn't seem to be a working gesture for a trackpad user to page back through a Claude session's history.

Expected behavior

A macOS trackpad user should be able to scroll back through a Claude session's history the way it worked in ~1.2.x.

Possible directions (just suggestions)

• An opt-out / setting to keep the plain wheel on local scrollback for users who prefer it, or
• A trackpad-friendly gesture for local scrollback that doesn't rely on Shift (horizontal on macOS trackpads), or
• Ensuring the forwarded-wheel path reliably reaches Claude's own transcript on trackpads.

Happy to test patches or provide more captures.