ponytail

Follow a decision ladder: first question whether the feature needs to exist (YAGNI), then check for existing code in the codebase, standard library functions, and native platform features before writing anything new. Stop at the first option that works and skip unrequested abstractions like single-implementation interfaces.

Prefer the standard library first, then native platform features, then dependencies already installed in the project. Never add a new dependency for something a few lines of code can accomplish. When two stdlib options are equal in size, pick the one correct on edge cases.

Lite builds what is asked but names a lazier alternative in one line. Full (the default) enforces the simplification ladder with the shortest working diff. Ultra is YAGNI-extremist: it deletes before adding and challenges the requirement itself while shipping a minimal solution.

Never simplify away input validation at trust boundaries, error handling that prevents data loss, security measures, accessibility basics, or anything explicitly requested. Also never skip understanding the problem — read all affected code fully before choosing a minimal fix.

Before editing, grep every caller of the function you plan to touch. Place one guard in the shared function all callers route through rather than patching only the path named in the bug report, which leaves sibling callers still broken.

Non-trivial logic such as branches, loops, parsers, or money and security paths should leave one runnable check behind — a small assert-based self-check or single test file. Trivial one-liners need no test, and full test frameworks are avoided unless requested.