ponytail

Apply a decision ladder before writing anything: check if the feature is needed at all, reuse existing helpers in the codebase, prefer standard library and native platform features, then write the minimum code that works. This keeps diffs small and avoids speculative abstractions.

Prefer the standard library or an already-installed dependency whenever it covers the requirement. Only add a new dependency when a few lines of existing tools genuinely cannot do the job, since each dependency adds maintenance and supply-chain cost.

Lite builds what is asked but names a lazier alternative in one line. Full, the default, enforces the ladder with the shortest working diff. Ultra is YAGNI-extremist, preferring deletion and challenging the requirement itself while shipping a one-liner.

Never simplify away input validation at trust boundaries, error handling that prevents data loss, security measures, accessibility basics, or anything explicitly requested. Hardware-facing code also needs calibration knobs that a minimal model cannot anticipate.

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