(feat) New skill: sell it agent

[wkoszek]

Summary

Adds /sellit — a first-10-sales skill for solo founders and small teams. When a founder says "find me customers" or "help me sell this," the skill:

• Reads the repo silently to form a product hypothesis and ICP (ideal customer profile)
• Challenges the founder's ICP before spending search budget — forces specificity ("that's a category, not a person")
• Hunts 10 real named buyers via web search, collecting name, title, company, hook, and contact channel
• Outputs sellit-hitlist.html — a plain HTML file with every prospect, pre-written messages, and mailto buttons that open the email client with subject and body pre-filled
• Ends with a 48-hour assignment — 3 concrete numbered actions, not suggestions

The skill is intentionally anti-sycophantic: no "great answer!", no market analysis, no strategy sections. Hit list and assignment only.

Files added

• sellit/SKILL.md.tmpl — skill template (source of truth)
• sellit/SKILL.md — generated skill file
• docs/superpowers/specs/2026-03-28-sellit-design.md — design spec
• docs/superpowers/plans/2026-03-28-sellit.md — implementation plan

Test plan

• Run /sellit on a repo with a README — verify it reads silently, challenges ICP, and produces a hit list
• Verify sellit-hitlist.html renders in a browser with working mailto buttons
• Test skip flow — say "just find buyers" during Phase 2 and confirm it skips to ICP challenge
• Confirm skill triggers on natural language ("find me customers", "who should I sell to")