Feature: Visual prompt separator for easier scroll navigation

Problem

When working on long sessions with Claude Code, it becomes very difficult to find where my prompts are when scrolling back through the terminal output. The user input (> prefix) is visually too subtle compared to Claude's responses (● prefix), making it hard to locate my messages in long conversations.

Current Workaround Attempted

I tried using UserPromptSubmit hooks to inject a visible separator bar, but:

• stdout from hooks only appears as a small gray "hook success: ..." label — not as a prominent visual element
• stderr is suppressed for exit code 0
• ANSI escape codes are not interpreted in the hook success label (rendered as raw text)
• There is no way to inject colored/styled output into the terminal via hooks

Proposed Solution

Add a visual prompt separator feature — a configurable colored horizontal bar that appears before each user prompt, making it easy to spot user inputs when scrolling back.

This could be implemented as:

1. A setting in settings.json (e.g., "promptSeparator": true or "promptSeparator": { "style": "bar", "color": "yellow" })
2. A hook capability that allows hooks to output styled/colored text to the terminal (not just plain text labels)
3. A built-in visual distinction — making user prompts more visually prominent by default (e.g., colored background, thicker border, horizontal rule)

Visual Reference

Currently, the user input area looks like this — very hard to find when scrolling:

> my prompt text here
└ UserPromptSubmit hook success
● Claude's long response...
  (many lines)
  ...
> next prompt (hard to find!)

Desired behavior — a visible separator that's easy to spot:

━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
> my prompt text here
● Claude's response...

Environment

• macOS (Darwin 25.1.0)
• Claude Code CLI
• Terminal: default macOS Terminal

🤖 Generated with Claude Code