LeanFrontier: the fork was the test (Field Note 10)

Field Note 10 — “The Fork Was the Test” — records the first submission to arrive from another person’s fork: PR #167 defines the Tribonacci sequence and proves that every term past zero is positive and that finite partial sums satisfy a telescoping identity — a genuine recurrence-sequence result, not a re-labelled Fibonacci or Padovan one. A Mathlib base bump moved underneath the PR mid-flight, a clean rebase put it back at the boundary, and the receiver — not a mathematical reviewer — decided whether it could cross. The corpus is at carlok.github.io/LeanFrontier.