[Bug]: Terminal background flickers on every redraw when background transparency is enabled

Operating system

macOS

Orca version

v1.4.102

Details

Summary

During AI-driven development, every time an agent runs (i.e., the terminal screen updates/redraws), the terminal background flickers for an instant.
Through further investigation, the flicker turns out to be tied to the background transparency setting (see Investigation below).

Steps to Reproduce

1. Open a project in Orca ADE
2. Make sure background transparency is enabled (opacity < 1)
3. Start an agent in the terminal (e.g., Claude Code, Kimi Code)
4. Have the agent continuously stream/update its output
5. Observe the background flicker for an instant on every screen update (see attached recording)

Expected Behavior

The background stays stable and does not flicker on redraw, regardless of the transparency setting.

Actual Behavior

With background transparency enabled, the background flashes/flickers for an instant on every output update (redraw).

Frequency

Always — reproduced with at least both Kimi Code and Claude Code.

Investigation / Findings

• Setting background opacity to 1 (fully opaque) makes the problem disappear. ← strongest clue
• With transparency enabled, typing single characters in the terminal changes the background brightness step by step:
  • 1st character → background gets slightly darker
  • 2nd character → gets brighter
  • 3rd character onward → darker again
  • Pressing Delete → gets brighter
• This brightness change synchronized with each keystroke/redraw suggests the semi-transparent background layer is being re-composited (alpha being stacked / re-blended) on every screen update, rather than drawn once.

Environment

• Orca ADE version: v1.4.102
• OS: macOS 15.6.1
• Agents / CLIs: Claude Code, Kimi Code (reproduced with both)
• Theme: Dark (terminal theme: Kanagawa)
• Background transparency: enabled (opacity < 1) — problem disappears at opacity = 1
• Display: [ external monitor? / refresh rate / HiDPI — fill in if relevant ]

Additional Context

• Reproduced across multiple agents (Claude Code, Kimi Code), so it appears to be independent of the specific agent — pointing to the rendering/compositing layer.