The Geometry of Intervention: Eight strategies for influencing any four-phase process, derived from first principles

This paper derives, from first principles within the Generative Geometry framework (van der Klein, 2026), a complete framework for intervening in any process that proceeds through four sequential phases. The framework produces eight strategies (four to resist a crossing, four to enable it), a formula for the effectiveness of each (Crossing(k) = P0 x r^k), a proof that no strategy is geometrically privileged over any other, and structural conditions that determine which strategies are available at each point in the process. The key findings are: (1) going one fractal level deeper and covering all four sub-phases within any single phase produces approximately 96% blockade, regardless of which phase is chosen; (2) the step's current phase restricts which strategies are geometrically available -- earlier phases permit more options, later phases permit fewer; (3) a threshold decision (whether to engage at all) precedes all eight strategies and is itself governed by the same four-phase logic. Brief cross-domain verification is provided; detailed applications are published separately.