Ahmad Shah Khattak - BlogsLong-form writing on product engineering, systems, and AI.https://iahmadshah.me/en-usSecuring Multi-Tenant RAG: Recall Collapse, pgvector Filtering, and PostgreSQL ltreehttps://iahmadshah.me/blogs/authorization-before-retrieval-in-rag/https://iahmadshah.me/blogs/authorization-before-retrieval-in-rag/Why in-memory post-filtering causes recall collapse, how pgvector HNSW scans execute internally, and how to build hierarchical RBAC with PostgreSQL ltree.Fri, 21 Aug 2026 00:00:00 GMTThe Fast Shipping Strategies That Quietly Kill Productshttps://iahmadshah.me/blogs/product-strategy-failures/https://iahmadshah.me/blogs/product-strategy-failures/Most products don't fail because the idea was wrong. They fail because the team never stopped long enough to find out if the idea was right.Sun, 31 May 2026 00:00:00 GMTQuestioning Features Before Users Have Tohttps://iahmadshah.me/blogs/questioning-features-before-users-have-to/https://iahmadshah.me/blogs/questioning-features-before-users-have-to/Buildable features still need to survive pressure from users and the business.Thu, 14 May 2026 00:00:00 GMTRefactoring Is Often Delayed Designhttps://iahmadshah.me/blogs/refactoring-is-delayed-design/https://iahmadshah.me/blogs/refactoring-is-delayed-design/Refactoring is often the cost of assumptions that were never pressured early enough.Wed, 13 May 2026 00:00:00 GMT