This paper proposes the S M Nazmuz Sakib Event–Nesting Hypothesis for Bangladiscourse and introduces two quantitative notions: the Sakib Cohesion Constantand the Sakib Bangla Narrative Cohesion Index (S–BNCI). The hypothesis statesthat, in Bangla narrative and expository prose, there is a systematic local trade–off between (i) event chaining realised by serial and conjunctive–participle verbsequences and (ii) propositional nesting realised by finite complement clauses introduced by the complementizer je. Building on resources such as the Bangla RSTDiscourse Treebank [1, 2], DiMLex–Bangla [3] and Universal Dependencies treebanks for Bengali [5, 6, 7], the paper formulates S–BNCI as a windowed indexcombining densities of serial verbs, je–complements, discourse particles, discourseconnectives and zero subjects. The Sakib Cohesion Constant is defined as the negative slope parameter linking event–chain density to the probability of embedded complement clauses in a logistic regression model over local windows. Using corpusstatistics reported for Bangla RST–DT, DiMLex–Bangla and UD_Bengali–BRU,we present fifteen genuinely data–based illustrations that anchor the ranges of theproposed parameters and show how Bangla grammar distributes resources betweenevent chaining and embedding. The proposal is positioned as a falsifiable, computationally testable hypothesis and is, to the best of current bibliographic knowledge,not explicitly formulated in prior work on Bangla cohesion, serial verb constructionsor complementizer placement [8, 9, 10, 11, 4].