--- title: "Echoes" canonical: "https://current.tinyfish.ai/issue/48/echoes" publication: "TinyFish" publisher: "TinyFish" language: "en-US" guide: "https://current.tinyfish.ai/llms.txt" permalink: "https://current.tinyfish.ai/issue/48/echoes" issue: 48 section: "echoes" description: "Past infrastructure decisions echoing in today's production realities" authors: ["Sable Whitford","Sevda Polat"] published: 2026-09-28 updated: 2026-09-25 articles: 15 --- # TinyFish > CURRENT is a journal about AI agents in production, for the engineering and product leaders who have to make them work. Drawing on experience building enterprise web agents, it explains why the demo succeeded and the deployment didn't, and what that means for choosing vendors, briefing the board, and avoiding mistakes others have already made. [Read on the website]() ## Issue 48 — Echoes Past infrastructure decisions echoing in today's production realities ### Historical Anchor - [XCON and the Maintenance Paradox]() — By [Sable Whitford]() · Published 2026-09-24 · Format: Historical Anchor XCON configured VAX computers for Digital Equipment Corporation through the 1980s, hundreds of orders a day, and it worked. Start there. Early on, maintaining it meant teaching it: find the gap, add the knowledge. Years and contributors later, developers were uncertain what some rules did and reluctant to touch them. Digital started a redesign not because the system was failing but because it was getting hard to change. That transition has less to do with expert systems than with what happens whenever encoded knowledge becomes the thing you can't turn off. ### Scale in Numbers - [Twenty Thousand Parts]() — By [Sable Whitford]() · Published 2026-09-24 XCON was an expert system that configured Digital Equipment Corporation's computer orders — matching components, checking compatibility, generating floor plans. It went into production in 1980 with about 700 rules. By 1987 it had grown to [6,200 rules](https://cdn.aaai.org/AAAI/1987/AAAI87-148.pdf) drawing on roughly 20,000 parts, and it worked: DEC's engineers reported "no problem with XCON's performance." ### Practitioner Voice - [The Bot Graveyard Still Has Live Permissions]() — Published 2026-09-24 *Nora Keepwell does not exist. Or rather, she exists the way a composite sketch exists: assembled from documented experiences, peer-reviewed interviews, audit findings, and the accumulated scar tissue of enterprise automation programs that scaled well past the point where anyone remembered the original business case.* ### Parallel Failure Modes - [When the List Broke]() — By [Sable Whitford]() · Published 2026-09-24 · Format: Parallel Failure Modes Anti-virus software started with a simple bet: name every known threat, update the list weekly, scan for matches. It worked fine when there were a few hundred viruses. Then new malware samples hit hundreds of thousands a day, and the list became impossible to keep current. The industry had to surround signatures with behavioral detection, reputation scoring, and heuristics — layers that could characterize threats nobody had named yet. A story about what happens when the thing you maintain grows faster than you can update it. - [When the Combinations Outgrew the Room]() — By [Sable Whitford]() · Published 2026-09-24 · Format: Parallel Failure Modes After deregulation, American Airlines carried over 500,000 fares in its reservation system. Every rule made sense on its own. But nobody could predict what the system would do when you changed one, because the interactions between fare classes, routing constraints, and capacity controls across a flight network had outgrown any person's ability to hold them. The fix wasn't better rules. It was a statistical layer that absorbed combinations no human could work through by hand. A different kind of maintenance failure than the one next door, with a similar ending. ### Source Trails - **Assessing the Maintainability of XCON-in-RIME** — [Source]() — Published 2026-09-24 Documents how XCON's 6,200-rule expert system worked well operationally while quietly becoming unmaintainable. - **Yield Management at American Airlines** — [Source]() — Published 2026-09-24 The Edelman Award paper that defined airline revenue management — and its permanent dependency on human recalibration. - **Revenue Management Systems as Symbiotic Analytics Systems** — [Source]() — Published 2026-09-24 Field study showing airline pricing systems can't function without analysts routinely overriding their automated decisions. - **AV-TEST Institute Malware Statistics and Trends** — [Source]() — Published 2026-09-24 Live data tracking the growth from thousands of annual malware samples to over 450,000 new ones daily. - **GSA Should Strengthen Security of Its Robotic Process Automation Program** — [Source]() — Published 2026-09-24 Audit found 55 of 56 decommissioned-bot custodians still had access past policy deadlines. A governance case study. - **Improving Revenue Management Decision Making by Evaluating Analyst-Adjusted Forecasts** — [Source]() — Published 2026-09-24 Examines how human analysts override automated demand forecasts and how hard it is to measure whether that helps. ### Past Articles - [The Chart That Cannot Be Unwritten]() — By [Sevda Polat]() · Published 2026-09-17 · Format: Never Erase A chiropractor recopied a patient's chart after a malpractice complaint arrived. The rewritten version described a patient who had improved and was satisfied. The original, which the patient happened to have copied, described neither. Healthcare learned case by case, and expensively, that altering a clinical record does more than revise the past. It cuts the reasoning out from under decisions other people already made on the strength of it. - [The Ledger That Never Forgets]() — By [Sevda Polat]() · Published 2026-09-17 · Format: Never Erase In 1494, a Franciscan friar wrote down what to do when you post the wrong number: don't erase it. Add a second entry explaining the mistake, then record the correction. Three entries where one scratch-out would do. Venetian merchants had already settled on the slower method, and eventually federal law agreed with them. The wrong entry still belongs in the book. Any system that overwrites what was there before faces the question they answered. - [What Stays Behind]() — By [Sevda Polat]() · Published 2026-09-17 · Format: Conservation Framework In 1987, a conservation scientist soaked treated ceramics in solvent for eight hours. Roughly half the resin stayed behind. The treatment was considered reversible. Barbara Appelbaum argued that her profession needed a better question than whether something could be undone, and proposed asking instead what any intervention leaves available to whoever has to work on the object next. Nearly four decades later, the W3C is working out when software agents should be allowed to commit users to transactions they cannot fully reverse — arriving at the same problem, apparently without knowing it had already been formalized. - [The Deputy Who Couldn't Tell Its Authorities Apart]() — By [Sable Whitford]() · Published 2026-09-10 · Format: Competing Lineages A 1960s proposal held that authority should travel with each request rather than pool under the caller's identity. It lost to identity-based access control — the model the companion piece traces. Then a compiler destroyed a billing file because the operating system couldn't tell the compiler's own permissions apart from its user's, and that failure got a name: the confused deputy. Agent systems are now rediscovering what capability-based security proposed before Unix existed. ## Other sections in Issue 48 - [Daily Brief]() - [Market Pulse]() - [Foundations]() - [Practitioner's Corner]() - [Vision]() ## More - [Publication guide]() - [Issue archive]()