v4.0.0

4.0.0 (2026-07-07)

• feat!: isolate every engine by default and add first-class system prompt override (20a9fe0)

Bug Fixes

• site: tighten hero CTA layout (e0380da)

BREAKING CHANGES

• flows on claude/codex/gemini/copilot/opencode that
  implicitly relied on ambient skills, MCP servers, or CLAUDE.md/AGENTS.md
  memory now run isolated by default. Add _isolated: false to restore
  the previous behavior, or declare the needed context explicitly in
  frontmatter.

Co-Authored-By: Claude Fable 5 noreply@anthropic.com