Long-form engineering notes on distributed systems, multi-tenant architecture, delivery guarantees, AI pipelines and release automation.https://musfiqdehan.comen-us© 2026 Md. Musfiqur Rahamanhttps://musfiqdehan.com/og/blog.pnghttps://musfiqdehan.com/https://musfiqdehan.com/blog/offline-first-pos-tauri-sync-outboxhttps://musfiqdehan.com/blog/offline-first-pos-tauri-sync-outboxA till that stops working when the internet does is a till that loses money. Here is the outbox-plus-idempotency contract that lets a Tauri desktop POS sell offline and replay safely into a Django backend - without double-charging anyone.Wed, 29 Jul 2026 00:00:00 GMTTauriReactSQLiteDjangoOffline-FirstIdempotencyPostgreSQLmusfiqdehan@gmail.com (Md. Musfiqur Rahaman)https://musfiqdehan.com/blog/decomposing-a-monolith-without-a-rewritehttps://musfiqdehan.com/blog/decomposing-a-monolith-without-a-rewriteSeams before services. How to extract modular services from a legacy monolith incrementally - with the data ownership rule, the strangler pattern, and an honest list of what you give up the moment a function call becomes a network call.Wed, 08 Jul 2026 00:00:00 GMTArchitectureMicroservicesDjangoRefactoringLeadershipDockermusfiqdehan@gmail.com (Md. Musfiqur Rahaman)https://musfiqdehan.com/blog/lease-based-url-frontier-postgreshttps://musfiqdehan.com/blog/lease-based-url-frontier-postgresHow FOR UPDATE SKIP LOCKED plus expiring leases gives you a distributed, crash-safe work queue without adding a broker to your architecture - with the reaper, backoff and priority scheduling that make it production-grade.Thu, 18 Jun 2026 00:00:00 GMTPostgreSQLDistributed SystemsQueuesPythonConcurrencymusfiqdehan@gmail.com (Md. Musfiqur Rahaman)https://musfiqdehan.com/blog/four-stage-deduplication-pipelinehttps://musfiqdehan.com/blog/four-stage-deduplication-pipelineA cost-ordered cascade - URL hash, content hash, SimHash banding, then BGE-M3 semantic comparison - that kills the vast majority of duplicates with an index lookup and reserves embeddings for genuinely ambiguous pairs.Wed, 27 May 2026 00:00:00 GMTDeduplicationSimHashEmbeddingspgvectorMultilingual NLPPostgreSQLmusfiqdehan@gmail.com (Md. Musfiqur Rahaman)https://musfiqdehan.com/blog/at-least-once-redis-streamshttps://musfiqdehan.com/blog/at-least-once-redis-streamsRedis Streams consumer groups give you delivery guarantees; they do not give you correctness. What idempotent handlers, delayed retries, dead-letter streams and stale-message reclaim actually look like in production.Wed, 06 May 2026 00:00:00 GMTRedisStreamsReliabilityPythonIdempotencyQueuesmusfiqdehan@gmail.com (Md. Musfiqur Rahaman)https://musfiqdehan.com/blog/schema-per-tenant-django-multi-tenancyhttps://musfiqdehan.com/blog/schema-per-tenant-django-multi-tenancyRow-level tenancy is one missing WHERE clause away from a data breach. Schema-per-tenant moves isolation from something developers remember into something the database enforces - and here is what it costs.Tue, 14 Apr 2026 00:00:00 GMTDjangoPostgreSQLMulti-TenancySaaSRBACArchitecturemusfiqdehan@gmail.com (Md. Musfiqur Rahaman)https://musfiqdehan.com/blog/holding-10k-dau-before-you-scale-uphttps://musfiqdehan.com/blog/holding-10k-dau-before-you-scale-upConnection exhaustion, N+1 queries, missing composite indexes and recomputed dashboards - the four things that actually limited a Django SaaS, and why PgBouncer came before hardware.Thu, 19 Mar 2026 00:00:00 GMTPostgreSQLPgBouncerDjangoPerformanceRedisDeploymentmusfiqdehan@gmail.com (Md. Musfiqur Rahaman)https://musfiqdehan.com/blog/one-api-three-clientshttps://musfiqdehan.com/blog/one-api-three-clientsWhat changes when the same backend has to serve a React dashboard, a React Native app and a biometric device on a gym LAN - untrusted clocks, offline buffers, and why the hardware client reshaped the API contract.Tue, 24 Feb 2026 00:00:00 GMTAPI DesignDjangoReact NativeIoTOffline SyncWebSocketmusfiqdehan@gmail.com (Md. Musfiqur Rahaman)https://musfiqdehan.com/blog/let-the-agent-propose-not-writehttps://musfiqdehan.com/blog/let-the-agent-propose-not-writeThe single boundary that separates an LLM feature you can point at production data from a demo you cannot - plus schema-validated extraction, provider fallback and cost accounting as engineering concerns rather than prompt concerns.Thu, 29 Jan 2026 00:00:00 GMTLLMAgentsGeminiLangChainReliabilityArchitecturemusfiqdehan@gmail.com (Md. Musfiqur Rahaman)https://musfiqdehan.com/blog/tag-driven-python-releaseshttps://musfiqdehan.com/blog/tag-driven-python-releasesEvery manual step in a release is a step someone will skip at 11pm. How tag-driven CI, generated changelogs, semantic versioning and Poetry lockfiles turned publishing a Python package into a single command.Thu, 11 Dec 2025 00:00:00 GMTPythonPoetryGitHub ActionsCI/CDOpen SourceVersioningmusfiqdehan@gmail.com (Md. Musfiqur Rahaman)