Claude Code CLI chat panel becomes unreadable / Unicode-mangled mid-session

What this error means

chat panel text rendered into garbled / unreadable characters — Unicode or terminal-redraw glitch is a Claude Code failure pattern reported for developers trying to fix claude code rendering corruption when mixing multibyte strings, ansi escapes, and binary blobs in long sessions. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.

Why this happens

Issue #59958 in anthropics/claude-code (opened 2026-05-17): Long-running Claude Code session with mixed encoding (Bahasa Malaysia commit messages, em-dashes, ANSI-color output from railway/gh/vercel, base64/git blobs) causes terminal render to drop into broken state. Model continues processing correctly — only the TUI layer is affected. Verified environment: Claude Code v2.1.143, macOS 26.1, VS Code integrated terminal, Opus 4.7 model. Affects paying users running extended coding sessions. Not covered in covered-errors.md.

Common causes

• Issue #59958 in anthropics/claude-code (opened 2026-05-17): Long-running Claude Code session with mixed encoding (Bahasa Malaysia commit messages, em-dashes, ANSI-color output from railway/gh/vercel, base64/git blobs) causes terminal render to drop into broken state. Model continues processing correctly — only the TUI layer is affected. Verified environment: Claude Code v2.1.143, macOS 26.1, VS Code integrated terminal, Opus 4.7 model. Affects paying users running extended coding sessions. Not covered in covered-errors.md.

Quick fixes

1. Confirm the exact error signature matches chat panel text rendered into garbled / unreadable characters — Unicode or terminal-redraw glitch.
2. Check the Claude Code account, local tool state, and provider configuration involved in the failing workflow.
3. Compare the failing environment with a known working setup, then change one configuration value at a time.

Platform/tool-specific checks

• Verify the command, editor, extension, or API client that produced the error.
• Compare local settings with CI, deployment, or editor-level settings when the error appears in only one environment.
• Avoid deleting credentials, local model data, or project settings until the failing scope is clear.

Step-by-step troubleshooting

1. Capture the exact error message and the command, editor action, or request that triggered it.
2. Check whether the failure is account/auth, quota/rate, model/provider, local runtime, or deployment configuration.
3. Review the source evidence below and compare it with your environment.
4. Apply one change at a time and rerun the smallest failing action.
5. Keep the working fix documented for the team or deployment environment.

How to prevent it

• Keep provider/tool configuration documented.
• Record non-secret diagnostics such as tool version, provider name, model name, and command path.
• Add a lightweight check before CI or production workflows depend on the tool.

Sources checked

• https://github.com/anthropics/claude-code/issues/59958

Evidence note: Issue #59958 in anthropics/claude-code (opened 2026-05-17): Long-running Claude Code session with mixed encoding (Bahasa Malaysia commit messages, em-dashes, ANSI-color output from railway/gh/vercel, base64/git blobs) causes terminal render to drop into broken state. Model continues processing correctly — only the TUI layer is affected. Verified environment: Claude Code v2.1.143, macOS 26.1, VS Code integrated terminal, Opus 4.7 model. Affects paying users running extended coding sessions. Not covered in covered-errors.md.

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FAQ

What should I check first?

Start with the exact chat panel text rendered into garbled / unreadable characters — Unicode or terminal-redraw glitch text and the smallest action that reproduces it.

Can I ignore this error?

No. Treat it as a failed Claude Code workflow until the root cause is understood.

Is this guaranteed to have one fix?

No. The imported evidence supports the troubleshooting path above, but tool behavior can vary by account, plan, version, provider, and local configuration.

How do I know the fix worked?

Rerun the same command, editor action, or request. The fix is working when that action completes without chat panel text rendered into garbled / unreadable characters — Unicode or terminal-redraw glitch.