Update to fstack

{
  "description": "Apply when sequencing an addition, refactor, or rewrite. Remove dead weight, redundant validators, and stub references first, then build on the simpler base.",
  "included_files": [],
  "name": "principle-subtract-before-you-add",
  "skill_md_contents": "---\r\nname: principle-subtract-before-you-add\r\ndescription: \"Apply when sequencing an addition, refactor, or rewrite. Remove dead weight, redundant validators, and stub references first, then build on the simpler base.\"\r\nuser-invocable: false\r\ndisable-model-invocation: true\r\n---\r\n\r\n# Subtract Before You Add\r\n\r\nWhen evolving a system, remove complexity first, then build. Deletion gives you a simpler base, which makes the next addition smaller and less brittle.\r\n\r\n**Why:** Adding to a complex system compounds complexity. Removing first cuts the surface area, reveals the essential structure, and usually makes the next design obvious. Default to subtraction.\r\n\r\nMake simplification a continual investment. Leave the design slightly simpler and more capable behind the same or smaller surface than you found it.\r\n\r\n**The pattern:**\r\n- Sequence removal before construction\r\n- Cut before you polish (get to the minimum before investing in quality)\r\n- Design for observed usage, not speculative edge cases\r\n- No speculative validators, parsers, or guards beyond what the spec demands\r\n- Out-of-spec features drag validators behind them. Persistence, retry-on-startup, and schema migration each need guards to defend their inputs.\r\n- Simplify prompts (remove redundant instructions, excessive templates)\r\n- When a reference has no novel content, delete it rather than leaving a stub\r\n"
}