The relevance of the problem is determined by the existing gap between the multicomponent nature of discursive competence (DC) and the insufficient development of tools for its objective assessment at the B1–B2 levels in teaching Russian as a foreign language. Traditional assessment methods often focus on linguistic skills, failing to encompass integrative qualities of speech activity such as coherence, genre adequacy, and pragmatic appropriateness, which complicates the correction and planning of instruction. The aim of the article is to provide a theoretical foundation and develop a structure for a criteria-based assessment matrix for the comprehensive diagnosis of the development of discursive competence among international students. This tool is designed to outline the components of DC, propose a system of detailed descriptors for assessment, ensure unified approaches to testing, and serve as a basis for creating diagnostic tasks. The leading research approaches include the integrative approach and the criterion-referenced approach. The methodological framework synthesizes achievements from both domestic and foreign language pedagogy. The main results of the article are presented as a holistic diagnostic system comprising: a) a theoretical model of DC, structured into four skill groups (analytical-interpretive, productive-genre, interactive-strategic, metalinguistic and regulatory); b) a typology of communicative tasks simulating real student needs; c) a criteria-based assessment matrix with detailed descriptors for each skill; d) a scheme for interpreting the final score to determine the level of DC development. The theoretical and practical significance of the work lies in structuring the theoretical model of DC and creating a diagnostic tool that links theory with the practice of pedagogical measurement. The practical value of the matrix consists in enabling a shift from determining a general language proficiency level to a targeted diagnosis of each learner's strengths and weaknesses, which allows for the individualization of instruction, remedial work, and the development of self- and peer-assessment skills. The tool can be used for formative and summative assessment, and serve as a basis for developing digital diagnostic environments.