[BUG] Fullscreen render mode: no scrollbar and scrolling fully broken (arrows/PageUp/PageDown do nothing) once output exceeds one screen

Found 3 possible duplicate issues:

1. https://github.com/anthropics/claude-code/issues/70429
2. https://github.com/anthropics/claude-code/issues/71749
3. https://github.com/anthropics/claude-code/issues/2301

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### What happened In the fullscreen rendering mode (enabled via the in-app Claude Code option), once the terminal output grows past one screen there is no scrollbar rendered, and scrolling does not work at all. Arrow keys and Page Up / Page Down do nothing, so earlier output becomes inaccessible. ### Expected behavior When content exceeds the viewport, a scrollbar should appear and keyboard scrolling (Arrow keys, Page Up / Page Down) should move the viewport to reveal earlier output. ### Steps to reproduce 1. Enable fullscreen rendering mode via the in-app Claude Code option (fullscreen toggle). 2. Run a session that produces enough output to scroll past the visible screen. 3. Observe: no scrollbar appears. 4. Try to scroll up with Arrow keys / Page Up / Page Down — nothing happens. ### Environment Claude Code version: 2.1.195 OS: Windows 11 Pro (10.0.26100) Terminal: PowerShell 7.6.3 (pwsh) Render mode: Fullscreen ### Notes This looks distinct from the existing fullscreen scroll issues, where scrolling still works but is mouse-only or janky: [[BUG] Fullscreen renderer + CLAUDE_CODE_DISABLE_MOUSE=1: mouse wheel navigates prompt history instead of scrolling the viewport #70724](https://github.com/anthropics/claude-code/issues/70724) — mouse wheel navigates prompt history with CLAUDE_CODE_DISABLE_MOUSE=1 v2.1.150: scroll wheel no longer scrolls conversation — sends arrow keys instead #65833 — scroll wheel sends arrow keys instead of scrolling [[BUG] Fullscreen TUI mode has janky/non-smooth scrolling #56546](https://github.com/anthropics/claude-code/issues/56546) — janky / non-smooth scrolling [[BUG] Fullscreen rendering mode: scrolling is laggy/stuttering in VSCode integrated terminal on Windows #53699](https://github.com/anthropics/claude-code/issues/53699) — laggy scrolling in VSCode integrated terminal Here keyboard scrolling (arrows / PageUp / PageDown) is entirely non-functional and no scrollbar is rendered at all — not merely janky or mouse-only

yes, no scroll bar and scrolling is not wokring. it is very very fast while scrolling, feeling drained

its happning with me, not resolving at all

Also seeing this on macOS Terminal.app, Claude Code 2.1.204. Scrolling up through a long conversation is completely dead: mouse wheel, PageUp/PageDown, and arrow keys all do nothing, and no scrollbar renders once output exceeds one screen.

Notes:

• 2.1.203 was supposed to fix scroll ("fixed content jumping when scrolling up"), but the core "cannot scroll at all" behavior is still present on 2.1.203 and 2.1.204.
• Downgrading to 2.1.202 restores working scroll, so this is a regression introduced in 2.1.203.

Environment: macOS, Terminal.app (default), no tmux, Claude Code 2.1.204 (native installer).

Confirming this is still present in v2.1.202 on Windows 11 (10.0.26100) / PowerShell — same environment as the original report, so it's not fixed as of 2.1.202.

Same symptom: in fullscreen render mode, once output grows past one screen the earlier output becomes inaccessible and scrolling doesn't get me back to it.

Clean workaround that fixed it for me: /tui default — relaunches the classic renderer (keeps the current conversation) and native terminal scrolling works again immediately. Launching with CLAUDE_CODE_DISABLE_ALTERNATE_SCREEN=1 does the same persistently.

One related observation in case it helps triage: switching into the fullscreen renderer also silently enabled copy-on-select (text auto-copies on mouse release), which was unexpected. So the fullscreen renderer changes two long-standing terminal behaviors at once — scroll capture and clipboard. (Copy-on-select is separately toggleable via /config.)