No Closed FormNo Closed Form — Haochi Zhang's notes on financial model risk, applied AI, and building reliable systems around imperfect models. Developed in public.https://noclosedform.com/Why Most Agent Demos Stop Before the Hard Parthttps://noclosedform.com/notes/why-agent-demos-stop/https://noclosedform.com/notes/why-agent-demos-stop/The gap between doing a task once and operating the same workflow repeatedly.Tue, 14 Jul 2026 00:00:00 GMTai-systemsDon't Write Fallbackshttps://noclosedform.com/notes/dont-write-fallbacks/https://noclosedform.com/notes/dont-write-fallbacks/A fallback postpones an error to where it's harder to diagnose; orthogonal modules remove the class.Fri, 10 Jul 2026 00:00:00 GMTbuildingThe MCP Surface and the Exec Surfacehttps://noclosedform.com/notes/mcp-surface-and-exec-surface/https://noclosedform.com/notes/mcp-surface-and-exec-surface/Why every LLM-generated tool call should cross one audited surface — and what stays in code.Mon, 06 Jul 2026 00:00:00 GMTai-systemsList the Excuses an Agent Will Use to Skip a Stephttps://noclosedform.com/notes/list-the-excuses-agents-use/https://noclosedform.com/notes/list-the-excuses-agents-use/Models don't cut corners; they generate a reason to. Name the rationalizations up front.Thu, 02 Jul 2026 00:00:00 GMTai-systemsFinancial RAG Is Not Just Document Searchhttps://noclosedform.com/notes/financial-rag-is-not-document-search/https://noclosedform.com/notes/financial-rag-is-not-document-search/Filings, market data, calculations, and provenance each want a different system layer.Wed, 24 Jun 2026 00:00:00 GMTfinance-modelsModel Risk as a Knowledge Representation Problemhttps://noclosedform.com/notes/model-risk-knowledge-representation/https://noclosedform.com/notes/model-risk-knowledge-representation/What's lost when a model inventory is treated as a spreadsheet, not a graph.Mon, 15 Jun 2026 00:00:00 GMTfinance-modelsA Standard for Agent-Built Projectshttps://noclosedform.com/notes/a-standard-for-agent-built-projects/https://noclosedform.com/notes/a-standard-for-agent-built-projects/Separate project facts, agent behavior, rules, and execution — before implementation begins.Sat, 06 Jun 2026 00:00:00 GMTbuildingEvidence That Can Be Tracedhttps://noclosedform.com/notes/evidence-that-can-be-traced/https://noclosedform.com/notes/evidence-that-can-be-traced/Traceability isn't a source column; it's every number reaching back to its raw fact.Thu, 28 May 2026 00:00:00 GMTfinance-models