Bug: All previous prompts accumulate and re-appear in the next input (Windows)

Description

After each response completes, all previously entered prompts in the session are automatically populated into the next > input prompt. Each new input adds to the accumulated text, causing every subsequent message to contain the full history of all prior inputs.

Reproduction Steps

1. Start a new Claude Code session: claude
2. Type hello and press Enter
3. Wait for response to complete
4. Observe: > hello appears pre-filled in the next prompt
5. Type test and press Enter (actual sent text: hello\ntest)
6. Wait for response to complete
7. Observe: > hello\ntest appears pre-filled in the next prompt
8. This continues to grow with every input

Expected Behavior

After a response completes, the > prompt should be empty, ready for new input.

Actual Behavior

Every previous input from the session is concatenated and pre-filled into the next > prompt. The accumulated text is sent as part of the next message, causing confusion and token waste.

/clear typed into the prompt is also treated as regular input text (not as a command), because it gets appended to the accumulated buffer.

Environment

• OS: Windows 11 Pro 10.0.26200.8037
• Claude Code: 2.1.97 (native install via claude install)
• Node.js: v24.14.1
• Git: 2.53.0
• Terminal: Windows Terminal (PowerShell) and VS Code integrated terminal
• Shell: PowerShell 5.1

Additional Context

• This issue occurs on only one specific PC. Other PCs with the same Claude Code version do not exhibit this behavior.
• Reproduced in both VS Code terminal and standalone Windows Terminal.
• Reproduced with IME (Japanese input) both enabled and disabled.
• Reproduced after updating from v2.1.71 to v2.1.97.
• Reproduced after switching from npm install to native install (claude install).
• npm global @anthropic-ai/claude-code was also installed; both npm and native versions exhibit the issue.
• Renaming/removing CLAUDE.md did NOT fix the issue.
• Renaming/removing ~/.claude/settings.json did NOT fix the issue.

Screenshots

(Will be attached in a follow-up comment — screenshots show the accumulation behavior across multiple inputs, including Japanese IME input)