Rediscovering Architectural Decision Records: How Persistent Design Context Improves LLM Code Generation

[TechRxiv] Shingo Kitayama published a study proposing a tool called sqlew that repurposes architecture decision records (ADRs) — introduced in 2011 but shelved due to the manual burden of maintaining them — as external design memory for LLMs, enabling automatic ADR recording and structured-query selective retrieval via the Model Context Protocol (MCP), and establishing a pattern in which static instructions (CLAUDE.md) and dynamic rationale (ADRs) coexist. The author conducted a three-condition controlled experiment on the development of a 12.5-round TypeScript workflow approval system: no ADR, sqlew adopted from the start, and sqlew adopted retroactively (v2s). The paper reports that the sqlew condition reduced development time by 10.1% (496 minutes versus 552 minutes) and reduced total tool calls by 10.8%; after accounting for the additional round required in the no-ADR condition to add E2E tests (round 12.6, 29 minutes, 21,751K tokens), the time difference widens to 14.6%. Chain-of-thought keyword density analysis shows the reasoning pattern shifting from trial-and-error loops to context-based reasoning, with the density of references to prior decisions diverging at an accelerating rate (+21%→+64%→+137%). The author states that the most prominent finding…