This paper presents CSL (Causal Specification Language), the first programming and interaction formalism built entirely from the principles of Causal Theory (CT). Instead of describing computations through instructions, variables, memory, or control flow, CSL expresses systems as causal geometries composed of identities, relations, boundaries, flows, and dissipation fields. Each primitive corresponds exactly to one of the five CT constants: π (identity), √2 (relation), √3 (curvature), φ (growth/action), and ln 5 (dissipation). CSL programs specify shapes rather than sequences. A program consists of nodes, edges, surfaces, flows, and decay rules—constraints that the Causal Kernel evolves into a stable configuration. Because the kernel enforces the four Patriarch Theorems (contraction, orthogonal decomposition, curvature–growth inequality, and entropy–dissipation), CSL guarantees safety properties that conventional languages can only approximate: no deadlocks, no race conditions, no invalid states, and no temporal anomalies. This document defines the full grammar, semantics, invariants, execution rules, and supracausal operators of the language. It includes examples illustrating how computation emerges from geometric stabilization rather than algorithmic steps. CSL establishes the foundation for causal-native programming across the CT computing stack (Kernel → CVM → CSL → CAL → CAR → CT-UNIX), enabling systems where code and geometry are the same mathematical object. From the same author: causality theory CT united https://zenodo.org/records/17366521 10.5281/zenodo.17366521 causality united v2 https://zenodo.org/records/17564091 10.5281/zenodo.17564091