feat(ui): add chat font size multiplier setting

[roomote]

Related GitHub Issue

Closes: #8100

Roo Code Task Context (Optional)

This PR was implemented by @roomote per the request in issue #8100 based on feedback from Bruno in PR #8457.

Description

This PR attempts to address Issue #8100 by implementing a chat font size multiplier feature. Feedback and guidance are welcome.

Key implementation details:

• Scoped to ChatView only: Per Bruno's feedback, the font size multiplier only affects the ChatView component, not settings, onboarding, or auto-approve dropdown areas
• UI Settings control: Added a text input with number type (min 0.5, max 2, step 0.1) in the UI Settings section with a reset button
• Commands: Added three commands for keyboard control:
  • roo-cline.increaseChatFontSize - increases by 0.1 (capped at 2)
  • roo-cline.decreaseChatFontSize - decreases by 0.1 (capped at 0.5)
  • roo-cline.resetChatFontSize - resets to default value of 1
• Persistence: The setting is stored in global settings and persists across sessions

Test Procedure

1. Manual testing:

   • Open Roo Code extension
   • Go to Settings > UI section
   • Verify "Chat Font Size Multiplier" input is visible with default value of 1
   • Change the value (e.g., 1.5) and verify text in the chat view scales accordingly
   • Click reset button and verify the value returns to 1
   • Verify settings, onboarding, and auto-approve areas remain unaffected

2. Command testing:

   • Use command palette to run "Roo: Increase Chat Font Size"
   • Verify the chat font size increases by 0.1
   • Use command palette to run "Roo: Decrease Chat Font Size"
   • Verify the chat font size decreases by 0.1
   • Use command palette to run "Roo: Reset Chat Font Size"
   • Verify the chat font size resets to 1

3. Automated tests:

   • cd webview-ui && npx vitest run src/components/settings/__tests__/UISettings.spec.tsx
   • All tests pass

Pre-Submission Checklist

• Issue Linked: This PR is linked to an approved GitHub Issue (see "Related GitHub Issue" above).
• Scope: My changes are focused on the linked issue (one major feature/fix per PR).
• Self-Review: I have performed a thorough self-review of my code.
• Testing: New and/or updated tests have been added to cover my changes (if applicable).
• Documentation Impact: I have considered if my changes require documentation updates (see "Documentation Updates" section below).
• Contribution Guidelines: I have read and agree to the Contributor Guidelines.

Screenshots / Videos

N/A - UI changes are minimal (number input and reset button in settings)

Documentation Updates

• No documentation updates are required.
• Yes, documentation updates may be required to document the new commands and setting.

Additional Notes

This implementation follows Bruno's specific feedback from PR #8457:

1. Font size scaling is scoped to only the ChatView (not settings, onboarding, etc.)
2. Added UI control with text input for multiplier value (0.5-2) plus reset button
3. Added reset command alongside increase/decrease commands

Get in Touch

@roomote (automated assistant)

[roomote]

Rooviewer   See task on Roo Cloud

Review complete. Found 1 minor issue to address:

• Floating point precision in font size increment/decrement commands could display values like "1.2000000000000002"

_{Mention @roomote in a comment to request specific changes to this pull request or fix all unresolved issues.}

[roomote]

Floating point precision issue: using currentMultiplier + 0.1 can produce values like 1.2000000000000002 after repeated increments, which will display in the UI input field. Consider rounding to one decimal place:

Suggested change

	const currentMultiplier = visibleProvider.contextProxy.getValue("chatFontSizeMultiplier") ?? 1
	const newMultiplier = Math.min(2, currentMultiplier + 0.1)
	const currentMultiplier = visibleProvider.contextProxy.getValue("chatFontSizeMultiplier") ?? 1
	const newMultiplier = Math.min(2, Math.round((currentMultiplier + 0.1) * 10) / 10)

The same applies to decreaseChatFontSize below.

_{Fix it with Roo Code or mention @roomote and request a fix.}