[BUG] Windows Terminal input completely frozen starting from v2.1.30 (regression from v2.1.29)

[gongpyung]

Bug Description

Claude Code becomes completely unresponsive to keyboard input on Windows Terminal starting from v2.1.30. The screen appears frozen — no characters can be typed, and the input prompt is non-functional. Downgrading to v2.1.29 immediately resolves the issue.

Environment

• OS: Windows 11
• Terminal: Windows Terminal (native, not WSL)
• Shell: PowerShell / Git Bash (both affected)
• Node.js: v20.11.0
• Installation: npm (@anthropic-ai/claude-code)

Reproduction Steps

1. Install Claude Code v2.1.30: npm install -g @anthropic-ai/claude-code@2.1.30
2. Open Windows Terminal
3. Run claude
4. Attempt to type anything into the prompt
5. Result: No input is accepted. Screen appears completely frozen.

Expected Behavior

The prompt should accept keyboard input normally (as it does in v2.1.29).

Root Cause Analysis

Binary diff analysis of the bundled cli.js between v2.1.29 and v2.1.30 reveals the following significant changes:

1. New useInterval hooks (0 → 5)

v2.1.29 had zero useInterval-based animation hooks. v2.1.30 introduces 5 new useInterval hooks running at 50ms–1000ms intervals:

Hook	Interval	Purpose
Spinner position animation	50ms / 200ms	Glimmer effect calculation
Stalled detection timer	100ms	Tracks request duration
Stalled intensity interpolation	50ms	Smooth animation easing
Team name animation	1000ms	UI counter increment
Elapsed time tracker	100ms	Duration display

Each interval triggers a React state update → full Ink re-render → ANSI escape sequence generation → stdout write.

2. Rewritten spinner component

The spinner component was completely rewritten with new Box layout (flexWrap:"wrap", height:1, width:2), a reducedMotion parameter, and a reversed animation frame array — all adding layout computation overhead per render cycle.

3. Additional reactive state

Metric	v2.1.29	v2.1.30	Diff
useInterval hooks	0	5	+5
useRef	144	153	+9
useState	542	545	+3
setTimeout	302	308	+6
useMemo	83	87	+4
spinner/animation refs	182	204	+22

Why this breaks on Windows Terminal

Ink (React for CLI) re-renders the entire screen buffer on every state change. On macOS/Linux terminals with Synchronized Output (DEC mode 2026), these rapid re-renders are batched and handled efficiently. However, Windows Terminal's ConPTY layer processes ANSI sequences significantly slower, causing:

1. Rapid useInterval callbacks (50–100ms) trigger continuous React re-renders
2. Each re-render writes ANSI sequences to stdout via ConPTY
3. ConPTY cannot drain the output buffer fast enough
4. stdout write() blocks the Node.js event loop
5. Blocked event loop cannot process stdin (keyboard input)
6. Result: Screen appears frozen, input is impossible

prefersReducedMotion does NOT fix this

v2.1.30 added a prefersReducedMotion config option. Testing confirmed it does not resolve the issue — it only changes the visual representation (blinking dot instead of animated spinner) but the underlying useInterval hooks continue firing at the same frequency.

Suggested Fix

• Gate useInterval hooks behind a ConPTY/Windows detection check, or significantly increase their intervals on Windows (e.g., 500ms+ instead of 50ms)
• Make prefersReducedMotion: true actually disable or throttle the interval hooks, not just change visuals
• Consider using requestAnimationFrame or passive rendering instead of aggressive interval-based re-renders

Workaround

Downgrade to v2.1.29:

npm install -g @anthropic-ai/claude-code@2.1.29

Related Issues

• Severe screen flickering in VS Code/Cursor integrated terminal on Windows #18084 — Severe screen flickering in VS Code/Cursor integrated terminal on Windows (same Ink re-rendering root cause)
• [Bug] Windows Terminal Input Stream Loss After Command Execution #10736 — Windows Terminal Input Stream Loss After Command Execution
• [BUG] Windows: cmd (Command Prompt) rendering issue - text overlapping and garbled display since v2.1.3~v2.1.5 #19637 — Windows cmd rendering issue since v2.1.3

[github-actions]

Found 3 possible duplicate issues:

1. Keyboard input not working in v2.1.30 (Windows) #22906
2. [Bug] Claude Code TUI completely freezes on Windows startup without input #22970
3. [BUG] Input freezes on Windows when launching Claude Code from certain directories (native installer) #22997

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🤖 Generated with Claude Code

[jltx]

I'm seeing this too. I can't start any new sessions because I can't type into any of them!

[mimosel]

+1

[codemile]

@gongpyung if you press the ENTER key when Claude first starts, then it will unfreeze the terminal and you can use 2.1.31

I'm still testing this workaround to see if it's stable. While it unfreezes the keyboard for inputs the ANSI animations still seem flaky, but I've been able to by-pass this bug so far. If you forget to hit ENTER, then you're out of luck and have to restart Claude.

[codemile]

@gongpyung another workaround; if your terminal is already frozen, then selecting some text and pressing CTRL+V appears to unfreeze it.

[gongpyung]

@gongpyung if you press the ENTER key when Claude first starts, then it will unfreeze the terminal and you can use 2.1.31

I'm still testing this workaround to see if it's stable. While it unfreezes the keyboard for inputs the ANSI animations still seem flaky, but I've been able to by-pass this bug so far. If you forget to hit ENTER, then you're out of luck and have to restart Claude.

Wow..this actually works perfectly! How did you figure this out? Super impressive 😄
I’ll be using your approach for a while. Thanks a lot!