Terminal output corruption: Garbled characters (ГöÇ patterns) displayed during CLI operation

[misterpeople]

Description

When using happy-cli with the Opus 4.5 model, the terminal displays excessive garbled/corrupted text characters instead of clean output. The corrupted characters appear as repeated sequences like ГöÇГöÇГöÇ throughout the terminal, making it difficult to read the actual responses.

Environment

• happy-cli version: rust 2-feature-4 (feature-4)
• Model: Opus 4.5
• OS: Windows
• Terminal: Default terminal

Steps to Reproduce

1. Start happy-cli with Opus 4.5 model
2. Interact with the CLI (e.g., use MCP tools like change_title)
3. Observe the terminal output

Expected Behavior

Clean, readable text output without encoding artifacts.

Actual Behavior

The terminal displays corrupted characters (appears to be encoding issues) such as:

• ГöÇГöÇГöÇ repeated patterns filling most of the screen
• ГùÅ prefixes before actual content
• Гö£ and Гö┤ appearing in place of box-drawing characters or formatting

The actual responses (e.g., "Successfully changed chat title to: SOL Trading Bot Chat" and "Hey! How can I help you with the SOL Trading Bot today?") are visible but buried within the garbled output.

Additional Context

This appears to be a character encoding mismatch, possibly:

• UTF-8 box-drawing characters being rendered incorrectly in a terminal expecting a different encoding
• ANSI escape sequences not being properly handled
• Spinner/progress indicator characters not rendering correctly

The issue makes the CLI nearly unusable as most of the screen is filled with corrupted characters during the "thinking" phase.

[agokak]

Facing the same problem on windows. Also noticed that happy launches claude code from cmd.exe not powershell (correct me if i'm wrong). Can we configure that?