Scan a markdown vault and return concepts mentioned in multiple notes but without their own dedicated note. Applies fuzzy canonicalization and noise filtering.

Return gaps ranked by priority: frequency × diversity × novelty (higher = fill first).

[Pro] Generate prioritized research questions for the top N gaps. Each question comes with a priority score and factor breakdown.

[Pro] Sortition sampling — pick n random gaps from the LOW-priority long tail. Breaks confirmation bias by surfacing topics you'd never pick yourself.

[Pro] Export a CSV of top-priority gap concepts for Anki or other spaced-repetition tools. Writes to output_csv and returns the row count.