Middle Backend-arendaja

• Designed service boundaries and RabbitMQ contracts for HRTech backend decomposition, coordinating and reviewing two developers’ work. Following combined architecture and runtime changes, peak successful HTTP RPS grew from ~1,500 to ~8,000. • Built and shipped a staff activity audit log for an HR platform using Kafka and a transactional outbox. Implemented asynchronous event storage in a separate PostgreSQL database, deduplication by unique UUIDv7 event IDs, a diagnostic dead-letter topic, and role-based access controls. • Replaced a third-party Keycloak integration with an aiohttp client that reduced unnecessary dependencies and eased integration testing. Implemented user and service authorization and user-data updates. • Set up parallel pytest-xdist execution for ~2,000 tests, cutting CI runtime from ~20 to ~1.5 minutes (~13×) with separate test tables per worker. • Extracted ORM-independent Python Use Cases from Django Views/ViewSets (Clean Architecture), cutting module dependencies from ~321 to ~201 (about 37%); consolidated ~13 repeated user retrieval/permission checks and enabled database-free unit tests. • Implemented role-based access with Keycloak OAuth2/OIDC and composite roles, plus time-limited S3 presigned URLs for file access. • Investigated a PostgreSQL candidate-list query after bulk UPSERT with EXPLAIN ANALYZE. Repeated production measurements showed SQL Execution Time falling from ~17 s to ~100 ms and a switch from Seq Scan to an existing Index Scan after autovacuum thresholds were adjusted.

• Developed an NLP term extractor for educational-text complexity analysis (spaCy NER, reference dictionaries): ~5 s automated extraction versus ~20 min manual term search and checking per comparable text; linguists validated the automated results separately. • Developed ruBERT-based genre classification models, achieving an F1 score of 0.83 on the validation dataset. • Developed exam variant management and access rules for a Russian-language examination platform for international students. • Developed a Chromium-based Windows application in Visual Studio, restricted to the exam-platform website; helped avoid a ~RUB 500,000 purchase of a third-party proctoring system. • Helped introduce GitFlow and parallel development in a three-developer team: comparable work took ~2.5 instead of ~5 working days (~2× faster).