Technical writing on real-time messaging, WhatsApp Business Platform, Elixir, PostgreSQL, Elasticsearch, AI agents and evals.https://fedme.dev/enhttps://fedme.dev/blog/testing-medical-triage-agents-with-langwatch-scenario/https://fedme.dev/blog/testing-medical-triage-agents-with-langwatch-scenario/How I test a medical triage AI agent with LangWatch Scenario: a simulated user, judge criteria, scripted and free-running conversations, in pytest and CI.Wed, 16 Sep 2026 00:00:00 GMTai-agentsllm-evalspythontestingfederico.meini@gmail.com (Federico Meini)https://fedme.dev/blog/whatsapp-cloud-api-webhooks-at-scale/https://fedme.dev/blog/whatsapp-cloud-api-webhooks-at-scale/How to build a WhatsApp Cloud API webhook receiver that holds up: signature checks on the raw body, fast 200s, dedup, per-contact ordering and media handling.Thu, 03 Sep 2026 00:00:00 GMTwhatsappwebhookselixirphoenixfederico.meini@gmail.com (Federico Meini)https://fedme.dev/blog/backpressure-bulk-whatsapp-sends-elixir/https://fedme.dev/blog/backpressure-bulk-whatsapp-sends-elixir/Designing a bulk WhatsApp send engine in Elixir: demand-driven Broadway pipelines, per-number token buckets, retries with jitter and batched status tracking.Thu, 27 Aug 2026 00:00:00 GMTelixirwhatsappbackpressurebroadwayobanfederico.meini@gmail.com (Federico Meini)https://fedme.dev/blog/partitioning-a-1tb-postgres-table-without-downtime/https://fedme.dev/blog/partitioning-a-1tb-postgres-table-without-downtime/Partition a live 1 TB Postgres table without downtime: attach it as the DEFAULT partition, copy history out with Oban jobs, then swap in one short transaction.Tue, 18 Aug 2026 00:00:00 GMTpostgresqlpartitioningperformanceelixirobanfederico.meini@gmail.com (Federico Meini)https://fedme.dev/blog/postgresql-partitioning-in-practice/https://fedme.dev/blog/postgresql-partitioning-in-practice/How PostgreSQL partitioning behaves in practice: choosing the key and size, checking pruning with EXPLAIN, indexes, keys, retention and the Ecto gotchas.Wed, 12 Aug 2026 00:00:00 GMTpostgresqlpartitioningperformanceelixirfederico.meini@gmail.com (Federico Meini)https://fedme.dev/blog/lua-sandbox-for-ai-agent-tools-in-elixir/https://fedme.dev/blog/lua-sandbox-for-ai-agent-tools-in-elixir/How tv-labs/lua gives AI agents a sandboxed Lua runtime inside Elixir: exposing safe functions, setting limits and wiring code execution into the agent loop.Tue, 04 Aug 2026 00:00:00 GMTelixirai-agentsluasandboxingfederico.meini@gmail.com (Federico Meini)https://fedme.dev/blog/serving-medgemma-27b-on-modal-vllm/https://fedme.dev/blog/serving-medgemma-27b-on-modal-vllm/How I self-host MedGemma 27B as a scale-to-zero, OpenAI-compatible API on Modal: FP8 quantisation, GPU snapshots, two vLLM bugs and Gemma 3 tool calling.Wed, 22 Jul 2026 00:00:00 GMTllmvllmself-hostingmedgemmaai-agentsfederico.meini@gmail.com (Federico Meini)https://fedme.dev/blog/agent-handover-architecture-whatsapp/https://fedme.dev/blog/agent-handover-architecture-whatsapp/A practical architecture for AI agents that hand over safely: multi-agent transfers, a deterministic rules engine for high-risk calls, sandboxed tools, evals.Tue, 14 Jul 2026 00:00:00 GMTai-agentsmulti-agentguardrailsllm-evalswhatsappfederico.meini@gmail.com (Federico Meini)https://fedme.dev/blog/simulation-evals-for-llm-chatbots/https://fedme.dev/blog/simulation-evals-for-llm-chatbots/How to build simulation evals for LLM chatbots: persona-driven simulated users, LLM-as-judge rubrics, error rates for high-stakes flows and a feedback loop.Tue, 30 Jun 2026 00:00:00 GMTai-agentsllm-evalsllm-as-judgepythonfederico.meini@gmail.com (Federico Meini)https://fedme.dev/blog/cpusim-a-cpu-simulator-for-zanichelli/https://fedme.dev/blog/cpusim-a-cpu-simulator-for-zanichelli/I was reminded today of CPUSim, a browser CPU simulator I built for Zanichelli in 2020 to show students how machine code runs, one glowing register at a time.Wed, 17 Jun 2026 00:00:00 GMTfreelanceeducationcomputer-architecturetypescriptfederico.meini@gmail.com (Federico Meini)https://fedme.dev/blog/2021_08_12_ueberauth_state/https://fedme.dev/blog/2021_08_12_ueberauth_state/Überauth now uses the OAuth state parameter for CSRF protection, so custom state gets overwritten. Keep it in the session between request and callback instead.Thu, 12 Aug 2021 00:00:00 GMTelixirueberauthoauthauthenticationfederico.meini@gmail.com (Federico Meini)