We present a macroscopic theory of capillary condensation in slits formed by parallel walls of unequal length. Using the concept of an edge contact angle, we identify four distinct condensation states and derive Kelvin-like relations for their onset. The resulting phase diagrams, expressed in terms of wall geometry and contact angle, reveal two central organizing features: a geometric separatrix that divides distinct condensation regimes, and the wedge-filling threshold at $\theta =\pi /4$, which separates a rich four-state scenario from a simpler two-state one. These results demonstrate how geometry dictates the onset and suppression of condensation in confined systems.

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• Capillary interactions
• Collective effects in atomic physics
• Confinement
• Interface & surface thermodynamics
• Phase diagrams
• Phase transitions
• Surface states
• Wetting