feat: URL command inlines - !@https://url syntax

Summary

Add a command inline syntax that fetches and converts URLs to markdown on-the-fly, complementing the existing !`cmd` syntax with into.md integration.

Proposed Syntax

# Existing command inline (unchanged):
!`git status`

# New URL inline:
!@https://example.com/current-status

# Or explicit into.md call:
!`into https://news.ycombinator.com`

How It Would Work

1. Add new pattern: !@<url> for URL inlines
2. Fetch URL through into.md API
3. Replace inline with converted markdown
4. Process at the same time as !`cmd` inlines in src/imports.ts

Use Cases

• Live Data Agents: !@https://status.example.com for current system status
• Research Workflows: Pull in relevant articles/docs dynamically
• Competitive Analysis: !@https://competitor.com/pricing to inform decisions
• News-Aware Agents: Include current headlines in context

Alternative: CLI Helper

Could also expose as a standalone command:

# Standalone usage
into https://example.com > context.md

# Pipe to agent
into https://example.com | ma ANALYZER.md

Implementation Notes

• Add !@ pattern to src/imports.ts
• Reuse into.md client from URL imports feature
• Consider timeout for slow pages
• Error handling for unreachable URLs

Questions for Discussion

• Is !@url intuitive or confusing? Alternatives: !web(url), !fetch(url)
• Should we support selectors? !@https://example.com#main-content
• Rate limiting / caching between runs?

Related

This is part of exploring into.md integration opportunities.

Start in src/imports.ts and inspect the existing URL imports feature and its into.md client. Trace how !cmd inlines are processed, then determine the scope for handling !@https://url alongside them, including timeout and unreachable-URL behavior. Done means the proposed URL syntax is converted to markdown during processing with the agreed error behavior.