Path Composition in Biological-Information Syntax: Repair Interfaces, Evidence Downgrading, and Failure Propagation Conditions

This paper defines the composition layer for repair-interface paths in biological-information syntax. It introduces Comp_RI = (P_R, Seq_R, Join_R, Grade_R, Obs_R, Transfer_R, Fail_R) as a formal structure for determining when repair-interface paths already admitted under prior criteria may be composed into larger biological-information sequences. The analysis is positioned after the domain-independent definition of lawhood, the formal declaration of nucleic-acid-like syntax, Harmonic Operator Grammar, operator-family classification, and multi-layer repair-interface admissibility. Its central admissibility condition states that a composed sequence is admitted only where each component path is already admissible, each junction is declared, directionality or cyclicity is typed, observable classes remain distinguished, evidence grades are preserved or restricted, comparative-transfer status is explicit where relevant, and failure propagation is specified. The paper uses experimental and methodological evidence from adult wound healing, neuroimmune repair, organ regeneration, comparative regeneration, fetal scarless healing, single-cell and spatial mapping, and wound-related regulatory-program analysis. It assigns formal composition status to paths involving neural, immune, cellular, genomic-regulatory, and tissue-level repair layers, while preserving the evidential status of perturbation-defined relations, mapping studies, comparative-regeneration dependencies, developmental boundary cases, and methodological gates. The main contribution is a formal evidence-control layer for biological-information syntax. Repair-interface admissibility is treated as a condition on component paths, while repair-interface composition is treated as a second-order admissibility condition over the relations among admitted paths. The framework prevents evidence-grade inflation, observable-class collapse, unsupported comparative transfer, unresolved-intermediate erasure, and premature causal closure. It also distinguishes composition status from downstream thresholds such as mechanism closure, target-regime transfer, coordinate-level biological syntax, intervention design, therapeutic interpretation, and external biological realization.