leanlisted

# Lean Make software fast, light, and smooth — loads quick, responds instantly, holds memory flat, leaves nothing running behind it. Built for the reality that users rarely ask for performance: they ask for a feature, then quietly leave when it eats RAM or takes five seconds to open. **This skill is on from the first line of code.** The default mode is the inline gate below — build the lean version while writing the feature, in the main thread. The full pass is for existing projects and pre-ship checks. ## Governing rules 1. **Measure, then cut.** In a pass, never optimize from vibes: baseline, find the bottleneck, fix it, re-measure. Guessing produces premature optimization — complexity without user-visible gain. In build mode the binding defaults below are pre-paid by platform evidence: apply them without benchmarking. 2. **Fix the shared cause once.** The N+1 belongs in the query layer, not a memo at each call site. Check every caller of the slow path before patching where it hurt. 3. **Optimize user time, not machine time.** What users wait on: startup, first paint, navigation, hot interactions, the nightly job. Micro-tuning code nobody waits for is last, always. 4. **Memory should be flat.** After N cycles of the core loop, committed memory should look like after 1. Sustained growth is a leak until proven otherwise; a sawtooth that returns to baseline is GC, not a leak. 5. **Nothing outlives its job.** Timers, listeners, observers, subscriptions, watchers, child proc