feat: improve ov chat UX with rustyline and markdown rendering

[chenjw]

• Use rustyline for proper line editing (no ^[[D characters)
• Add markdown rendering with termimad
• Add command history support (~/.ov_chat_history)
• Add --no-format option to disable markdown
• Add --no-history option to disable command history

Description

Related Issue

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Refactoring (no functional changes)
• Performance improvement
• Test update

Changes Made

Testing

• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• I have tested this on the following platforms:
  • Linux
  • macOS
  • Windows

Checklist

• My code follows the project's coding style
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Any dependent changes have been merged and published

Screenshots (if applicable)

Additional Notes

[github-actions]

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⏱️ Estimated effort to review: 3 🔵🔵🔵⚪⚪

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🔒 No security concerns identified

⚡ Recommended focus areas for review Regression in reasoning output The "reasoning" event output always appends "..." now, even when content is <= 100 characters, which is a change from the old behavior. "reasoning" => { let content = data.as_str().unwrap_or(""); println!( " \x1b[2mThink: {}...\x1b[0m", truncate_utf8(content, 100) ); Missing import check The local truncate_utf8 function is used, but verify that it behaves the same as the removed crate::utils::truncate_utf8 to avoid unintended changes. fn truncate_utf8(s: &str, max_chars: usize) -> &str { if s.chars().count() <= max_chars { return s; } if let Some((idx, _)) = s.char_indices().nth(max_chars) { &s[..idx] } else { s } }

[github-actions]

PR Code Suggestions ✨

Explore these optional code suggestions:

Category	Suggestion	Impact
Possible issue	Fix tool result truncation check The "tool_result" event checks byte length (content.len()) instead of character count to decide truncation. This can incorrectly truncate strings with multi-byte Unicode characters. Use content.chars().count() instead. crates/ov_cli/src/commands/chat.rs [315-323] "tool_result" => { let content = data.as_str().unwrap_or(""); - let truncated = if content.len() > 150 { + let truncated = if content.chars().count() > 150 { format!("{}...", truncate_utf8(content, 150)) } else { content.to_string() }; println!(" \x1b[2m└─ Result: {}\x1b[0m", truncated); } Suggestion importance[1-10]: 6 __ Why: The suggestion addresses a correctness issue where the tool result truncation used byte length instead of character count, which could break with multi-byte Unicode. This is a solid improvement for robustness.	Low
	Fix reasoning event ellipsis logic The "reasoning" event always appends "..." even when the content is not truncated. Check if the content exceeds 100 characters before adding an ellipsis, and only truncate when necessary. crates/ov_cli/src/commands/chat.rs [304-310] "reasoning" => { let content = data.as_str().unwrap_or(""); - println!( - " \x1b[2mThink: {}...\x1b[0m", - truncate_utf8(content, 100) - ); + if content.chars().count() > 100 { + println!( + " \x1b[2mThink: {}...\x1b[0m", + truncate_utf8(content, 100) + ); + } else { + println!(" \x1b[2mThink: {}\x1b[0m", content); + } } Suggestion importance[1-10]: 4 __ Why: The suggestion correctly fixes the minor issue where the reasoning event always appends "..." even when content isn't truncated. This improves output readability without changing core functionality.	Low