Text truncated after URL/path when submitting prompt - only URL visible, rest of input disappears #208

Describe the bug

When entering a prompt that contains a URL or file path followed by additional text, the text after the URL/path is visible in the input UI while typing. However, when pressing Enter to submit the request, only the URL/path portion is sent - all text after it gets truncated and disappears from the actual request.

The behavior is:

1. Type a URL or path in the input field
2. Type additional text after the URL/path
3. The UI shows the complete text (URL/path + additional text)
4. Press Enter to submit
5. BUG: Only the URL/path is actually submitted - everything typed after it is truncated/lost

Affected version

Version: 0.0.334
Commit: 26896a6

Steps to reproduce the behavior

1. Start Copilot CLI with copilot
2. Type a prompt that includes a URL or path, for example:
   • read https://github.com/github/copilot-cli/issues see if theres any issue about text being truncated when submitted
   • /path/to/file explain what this does
   • @/some/file.ts can you refactor this
3. Observe that the full text is visible in the input field (URL/path + additional text)
4. Press Enter to submit the prompt
5. Observe: Only the URL/path portion is processed - the text after it is truncated

Expected behavior

The entire prompt including both the URL/path and the text after it should be submitted and processed by Copilot CLI. The full input visible in the UI should match what gets sent to the model.

Example:

• Input in UI: https://github.com/github/copilot-cli/issues analyze the recent issues
• Expected submission: https://github.com/github/copilot-cli/issues analyze the recent issues

Additional context

System Information

• OS: macOS (Darwin 24.6.0)
• Architecture: ARM64 (Apple Silicon)
• Terminal: Apple Terminal
• Shell: zsh
• Node version: v23.5.0
• Copilot CLI version: 0.0.334 (Commit: 26896a6)

Impact

This bug makes it impossible to provide context or instructions along with URLs/paths, forcing users to either:

• Submit the URL first, then provide context in a follow-up message
• Avoid using URLs/paths in prompts entirely
• Work around by putting the URL/path at the end of the prompt instead of the beginning

This appears to be an input parsing or submission bug where URLs/paths are being treated as delimiters or causing the subsequent text to be dropped during prompt submission, possibly related to how the CLI handles @ file mentions or URL parsing.