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Your AI Model Has a Retirement Date

What survives a model change, what expires with it, and how to split your team’s effort between the model you ship and the one that replaces it.

Joshua McDonald·Sep 24, 2026·9 min read

Latest

Joshua McDonaldSep 22, 2026

Fewer Wrong Exits: The Wayfinding Method Behind DC Metro’s New Signs

How WMATA replaced fifty years of piecemeal signage with decision points, progressive disclosure, and error-targeted design, and how to run the same method on your own product

11 min readpublic-transit

Joshua McDonaldSep 16, 2026

Your First Month Leading a New Team, Week by Week

Read and ask in week one, test what you heard in weeks two and three, set direction by month one. AI compresses about half the work.

7 min readengineering-mangement

Joshua McDonaldSep 13, 2026

Agents Raise the Price of a Big Team

Project Aristotle said how a team works together beats who is on it. Agent-assisted work changes the how. Bigger teams now cost more to coordinate than they used to.

7 min readleadership

Joshua McDonaldSep 8, 2026

The Human in the Loop Is Approving Everything

Routing by risk solves the throughput problem. It does not solve the harder one, which is that reviewers stop reviewing.

10 min readproductivity

Joshua McDonaldSep 3, 2026

Alchemy, Read by Someone Who Manages Engineers

Rory Sutherland’s 2019 book is filed under marketing. The chapter on why the need to look rational makes organizations act dumb belongs on every engineering manager’s desk.

15 min readsoftware-engineering

Joshua McDonaldSep 1, 2026

Four Hours to Build, Five Years to Own

AI cut the cost of building software. It did not cut the cost of owning it, and that is the larger number.

10 min readartificial-intelligence

Joshua McDonaldAug 26, 2026

Everything Says Urgent, So Stop Sorting on Arrival

The research on why the loud task wins, the prompt that scores importance without seeing the urgency markers, and what to do about the…

15 min readDecision Making

Joshua McDonaldAug 25, 2026

A Third of Feedback Makes Performance Worse

Kluger and DeNisi found feedback backfiring in 38 percent of cases. The failures have two things in common: no specific action and distance…

8 min readLeadership & Organizations

Joshua McDonaldAug 20, 2026

The Org Chart, the Tube Map, and Models That Are Wrong on Purpose

Ashby says a manager needs a model of their system. Every model is wrong. The London Tube map explains how both are true.

8 min readLeadership & Organizations

Joshua McDonaldAug 18, 2026

Only Variety Can Absorb Variety

Ashby’s law, the arithmetic of control, and why the manager is now the constraint

11 min readLeadership & Organizations

Joshua McDonaldAug 13, 2026

AI Made Writing Code Nearly Free. Reviewing It Got 91 Percent Slower.

Two and a half years of AI coding, as told by the industry’s own numbers, biases included

9 min readAI & Agents

Joshua McDonaldAug 11, 2026

Being Wrong in Public

Newton, Popper, the AWS Correction of Errors process, and how mistakes made in the open become the shoulders others stand on

8 min readLeadership & Organizations

Joshua McDonaldAug 6, 2026

The cost of changing your mind depends on two things: how fast feedback arrives, and how much got…

Two cases, three shaky sources, and the two things that actually decide the cost of changing your mind

9 min readEngineering

Joshua McDonaldAug 2, 2026

Every Improvement Made No Difference

Theory of Constraints, the lane drop at Clarksburg, and why local wins do not add up

12 min readLeadership & Organizations

Joshua McDonaldJul 30, 2026

Adding People Reduced Output

The Universal Scalability Law, cache coherence, restaurant kitchens, and the size at which an organization starts working against itself

14 min readLeadership & Organizations

Joshua McDonaldJul 27, 2026

Everything Is 90 Percent Done

Little’s Law, Kingman’s formula, and why the sprint board is full while nothing ships.

10 min readWork & Productivity

Joshua McDonaldJul 23, 2026

Amdahl’s Law for Org Charts

What a three-page paper from 1967 explains about two-pizza teams, monoliths, and why your calendar time refuses to shrink

8 min readLeadership & Organizations

Joshua McDonaldJul 21, 2026

What “Open Weight” Actually Means

A plain explanation of the version of AI you can download, keep, and run without asking anyone.

12 min readAI & Agents

Joshua McDonaldJul 16, 2026

Ask Your Dashboard What It Reads When Nothing Changed

Work metrics move when you do work. Impact metrics move when the work mattered. AI made the first kind free to move, and most dashboards…

12 min readTechnology & Systems

Joshua McDonaldJul 15, 2026

You Can’t Compress What You Can’t Grade

Adding an eval harness to TokenLens, and why it should have come before the compression work. A follow-up to “I Built a Prompt Compressor…

16 min readPersonal Essays

Joshua McDonaldJul 9, 2026

I Built a Prompt Compressor. The Most Useful Thing It Found Was Nothing

We’ve always compressed data to save time and money. What’s new isn’t the instinct. It’s that the codec is now a language model. That arc…

8 min readAI & Agents

Joshua McDonaldJul 8, 2026

You do need pronunciation files across the languages, account for speed variances - but you should…

You do need pronunciation files across the languages, account for speed variances - but you should… You do need pronunciation files across the languages, account for speed variances - but you should use a base file and t

1 min readTechnology & Systems

Joshua McDonaldJul 7, 2026

Let the Expensive Model Write the Instructions

I build dcaudiotours.com, a set of self-guided walking tours for Washington DC. Thirteen themed tours, eight neighborhood walks, each one a…

7 min readPersonal Essays

Joshua McDonaldJul 2, 2026

Who Reviews the Reasoning?

The code coming out of agents runs, and the reviewers shipping today catch the bugs. Nobody is reviewing the decision: was this the right…

6 min readEngineering

Joshua McDonaldJun 28, 2026

Do We Still Need the Sprint?

What incremental delivery means, once the cost of an increment falls through the floor, whether the two-week cadence is still earning its…

11 min readEngineering

Joshua McDonaldJun 18, 2026

The Preflight Check for Distributed Systems

The failure modes that take systems down, and where to look for each one

7 min readTechnology & Systems

Joshua McDonaldJun 16, 2026

What 10²⁶ Actually Means

The number that defines a “frontier model” in US and California law, in terms of time, hardware, money, and the handful of training runs…

9 min readAI & Agents

Joshua McDonaldJun 14, 2026

How an Export Control Rule Reaches an AI Model Running in a US Data Center

What the directive on Fable 5 and Mythos 5 says, how deemed-export law works, and the 1991 precedent. Sourced to primary documents.

9 min readAI & Agents

Joshua McDonaldJun 11, 2026

Claude Skipped Idempotency Because I Never Asked. So I Made Asking Unnecessary.

The code broke on a retry I never mentioned, and even when I ask for the fix, the first version is usually the wrong shape. The answer was…

11 min readEngineering

Joshua McDonaldJun 9, 2026

Why system design matters more as AI makes building faster

What AI still can’t reason about no matter how well you prompt it.

17 min readAI & Agents

Joshua McDonaldJun 4, 2026

robots.txt Told Crawlers Where to Stop. llms.txt Tells Agents Where to Go

What the file does, how to write one, and why retrieval is the part that actually matters.

8 min readAI & Agents

Joshua McDonaldJun 1, 2026

What a Jar of Peanut Butter Teaches About Agent Skill Security

A jar of peanut butter passes through a dozen hands before it reaches your toast, and you trust every one of them without thinking about…

10 min readAI & Agents

Joshua McDonaldMay 27, 2026

What an Agent Skill Is, and How to Write One

If you use an AI assistant for the same kind of task more than a few times, you have probably noticed the tax. Every session starts cold…

8 min readWork & Productivity

Joshua McDonaldMay 25, 2026

EARS, Fifteen Years On: The Requirements Format Built for the Agent Era

In 2009, Alistair Mavin sat with the airworthiness regulations for a Rolls-Royce jet engine control system and found something quietly…

14 min readEngineering

Joshua McDonaldMay 21, 2026

MCP, Plainly

A plain explanation of what MCP changes, and why role-based access is the part that gets hard.

7 min readTechnology & Systems

Joshua McDonaldMay 19, 2026

Teaching Probability Through Soccer: Built With Claude Code

A statistics site for middle and high school students, built around the math pro analysts actually use.

5 min readPersonal Essays

Joshua McDonaldMay 14, 2026

The Quiet Repricing of AI Coding Tools

Copilot, Cursor, Codex, and Claude Code all moved to usage-based billing inside twelve months. The driver is the same.

11 min readEngineering

Joshua McDonaldMay 12, 2026

Coordinating Parallel Engineering Work With Claude

I have written before about decomposing specs against team shape, and about the specific Claude Code primitives that make the decomposition…

34 min readEngineering

Joshua McDonaldMay 6, 2026

Just the Road: Notes on perspective in an industry being rebuilt under our feet.

My dad lives in southern Alabama near the ocean and I stay a few miles away near a beautiful community set on a golf course. I go every…

10 min readPersonal Essays

Joshua McDonaldMay 5, 2026

The Little Blue Menu and What It Already Knows About AI

There’s a Chick-fil-A in College Park, Maryland, that doesn’t look like a Chick-fil-A. They painted it blue instead of red. The menu…

6 min readEngineering

Joshua McDonaldApr 30, 2026

Six Prompts for Reading an Engineering Roadmap

When you need to come up to speed quickly on a project, a team, or some piece of work, you can have Claude analyze the documents and ask…

9 min readAI & Agents

Joshua McDonaldApr 28, 2026

Running a Small Team on a Big Project: Spec-Driven Development with Claude Code

Monday morning. Four engineers in the standup, a Q4 roadmap with fourteen features on it, a PM who already promised half of those to…

41 min readAI & Agents

Joshua McDonaldApr 23, 2026

I Used AI to Audit 7,200 Hospital Price Files. It Found Something the Code Missed.

The story of a real data quality bug, how it got caught, and what it means for data engineering.

14 min readTechnology & Systems

Joshua McDonaldApr 21, 2026

The Prototype Got Cheap. The Product Didn’t.

On the widening distance between a working prototype and a production system.

11 min readTechnology & Systems

Joshua McDonaldApr 16, 2026

A Spring Break Commute, Five Dollars, and the State of Multilingual Text-to-Speech

Most people’s mental model of AI stops at the chat window. Type a question, get an answer, move on. That framing made sense in 2023 when a…

13 min readTechnology & Systems

Joshua McDonaldApr 13, 2026

You Don’t Have to Write Code to Need a CLAUDE.md

Setting Up Claude’s Memory for Writers, PMs, Researchers, and Everyone Else

16 min readAI & Agents

Joshua McDonaldApr 9, 2026

Day 1

The First Morning

13 min readEngineering

Joshua McDonaldApr 7, 2026

When You Can Build Anything, How Do You Decide What to Build?

Every engineering team eventually faces this question, and fifty years of business theory offer some guidance on how to answer it.

13 min readLeadership & Organizations

Joshua McDonaldApr 2, 2026

Spec Driven Development and Managing software projects in 2026 using AI development tools

Bottom Line Up Front: AI tools now generate code faster than teams can review it, and the old process of catching mistakes in pull requests…

18 min readEngineering

Joshua McDonaldMar 31, 2026

Building a Local AI Coding Assistant: VS Code + Ollama + Small Language Models

Why Build This (And Why You Probably Shouldn’t)

20 min readEngineering

Joshua McDonaldMar 26, 2026

Nudge Theory Revisited: Writing Tickets for Humans and Machines

Using ideas from behavioral economics to improve ticket writing, especially now that large language models are reading your tickets as…

10 min readWriting & Communication

Joshua McDonaldMar 23, 2026

Your Team Doesn’t Need Well-Rounded Engineers. It Needs a Well-Rounded Team.

Most engineering managers follow a familiar routine during performance reviews. You meet with a team member, recognize some things they do…

9 min readLeadership & Organizations

Joshua McDonaldMar 19, 2026

Purpose Is Everything

How to Set a North Star and Then Actually Deliver on It

17 min readWork & Productivity

Joshua McDonaldMar 17, 2026

I Built a DC Transit Companion with AI on My Commute using my iPhone. Here’s what I learned.

I built a DC Metro companion app called “What’s Up Metro DC” in nine days, using only my iPhone during my commute from Shady Grove to…

30 min readPersonal Essays

Joshua McDonaldMar 12, 2026

The Best Engineering Leaders I’ve Seen All Have One Thing in Common: They’re Calm When Everything…

There’s a moment in every engineer’s career when the pager goes off, and the world feels like it’s ending. The dashboard is a wall of red…

6 min readLeadership & Organizations

Joshua McDonaldMar 10, 2026

How AI Dev Tools Can Turn Your Cloud Bill Into Useful Insights

You manage a service team that owns a few services running in your organization. It’s Tuesday morning. A budget alert lands in your inbox…

10 min readTechnology & Systems

Joshua McDonaldMar 4, 2026

When Every Engineer Is a Manager

Every new engineering manager experiences what I call The Backseat Driver moment. You know the feeling: someone else is driving, and you…

22 min readAI & Agents

Joshua McDonaldMar 2, 2026

n(n−1)/2

Why Your Team Is Drowning in Conversation and How Math Explains Everything

28 min readEngineering

Joshua McDonaldFeb 26, 2026

If Your Career Were a Product, Would Anyone Invest?

Most people never use 1:1 meetings, running documentation, and a skills matrix until it’s too late.

7 min readLeadership & Organizations

Joshua McDonaldFeb 23, 2026

Why Every Engineering Team Needs a Monthly Business Review

Imagine it’s the end of the quarter. Leadership is preparing the board deck, and someone asks, “What did engineering actually ship this…

7 min readLeadership & Organizations

Joshua McDonaldFeb 19, 2026

Understanding Directed Acyclic Graphs (DAGs) with a Baseball Analogy

Stop struggling with complex tech jargon, Learn what a Directed Acyclic Graph (DAG) is through the lens of a high stakes baseball play.

9 min readTechnology & Systems

Joshua McDonaldFeb 16, 2026

The Efficiency Illusion: Why Your AI Strategy is Accelerating Inefficiency, and How to Pivot to…

Stop making your inefficiencies faster. Automating a broken workflow doesn’t create value; it just accumulates technical debt at machine…

6 min readAI & Agents

Joshua McDonaldFeb 11, 2026

What a 15th-century lawsuit and a lead letter ‘A’ can teach us about the age of AI

The revolution of the 15th century wasn’t defined by the scent of old paper or libraries. Instead, it was shaped by the strong, industrial…

7 min readCulture & Ideas

Joshua McDonaldFeb 5, 2026

Build Your Own AI General Contractor: A Practical Simulation Implementing Deterministic Guardrails…

In my previous article, I explained why the time of the “Handyman AI”, one model trying to do everything, is over. I suggested that…

13 min readAI & Agents

Joshua McDonaldJan 22, 2026

Stop Hiring “Handyman” AI: Why Production Requires a General Contractor

If you want to go from basic prototypes to systems that work at scale, you need more than better prompts. You also need a new way to…

6 min readAI & Agents

Joshua McDonaldJan 19, 2026

What the Longest Escalator in the Western Hemisphere Teaches Us About AI

If you live in the DC area, you know about the Wheaton Metro station. It’s home to the longest single-span escalator in the Western…

4 min readAI & Agents

Joshua McDonaldJan 18, 2026

Why Your AI Sounds Like a Corporate HR Department (And How to Fix It)

Note: This is an excerpt from my new book, THE ART OF WHISPERING TO MACHINES, available now on Amazon.

4 min readAI & Agents

Joshua McDonaldJan 17, 2026

Why Your AI Feels Slow: The “Baggage Claim” Theory of Latency

When Houston Airport first opened, executives faced a big problem. Passengers were upset about how long they had to wait for their bags…

5 min readAI & Agents

Joshua McDonaldJan 16, 2026

Why AI Forgot Your Name: The “Vanishing Whiteboard” Theory

AI doesn’t have a brain. It has a sliding window. Here is how to stop it from losing your data.

3 min readAI & Agents

Joshua McDonaldJan 16, 2026

How to Stop AI Hallucinations by Teaching It to Say “I Don’t Know”

Your AI isn’t lying to deceive you. It’s lying to please you. Here is the engineering fix.

3 min readAI & Agents

Joshua McDonaldJan 15, 2026

Why Most AI Models Can't Count the Letter "R" in Strawberry

A non-technical guide to Tokenization: why AI fails at simple math and spelling.

3 min readAI & Agents

Joshua McDonaldJan 13, 2026

Stop Treating AI Like a Brain. Treat It Like a Stadium.

Why your prompts are failing and the single mental shift that fixes them.

4 min readAI & Agents

Joshua McDonaldNov 20, 2025

What a trip to the supermarket can teach you about writing security tickets that engineers actually…

This is a story about connecting threads and combining ideas from different experiences, as much as it is about engineering, security, or…

11 min readWriting & Communication

Joshua McDonaldOct 16, 2025

Engineering Teams in the Age of Agentic AI

For years, the default approach to building ML products that solved business problems was to establish a research-heavy organization, with…

7 min readTechnology & Systems

Joshua McDonaldJun 22, 2021

Reading list

1 min readEssays

Joshua McDonaldMay 14, 2021

Crockpot Pumpkin and Chorizo Chili

This easy to make slow cooker chili combines the spices of India and Mexico to create a truly unique taste.

3 min readFood & Home

Joshua McDonaldApr 25, 2021

Three things to avoid and three things to do to foster open communication in teams

Perhaps the most important thing you can learn to be both a more effective team member and leader is to learn the art of asking questions…

7 min readLeadership & Organizations

Joshua McDonaldApr 19, 2021

On testing software

I’ve taught some college courses and have always been asked to provide a teaching philosophy as a guide to both students, but also the…

8 min readEngineering

Joshua McDonaldAug 3, 2020

Money can’t buy loyalty — intrinsic and extrinsic motivation

There are two two types of motivation, intrinsic and extrinsic. Intrinsic motivation comes from within. It’s something you do for the love…

5 min readLeadership & Organizations

Joshua McDonaldJun 29, 2020

Laid Off — What to Do When You Don’t Know What to Do

Practical tips for anyone looking for work

8 min readPersonal Essays

Joshua McDonaldJun 25, 2020

What matters now?

How to use Objectives and Key Results to narrow your focus on what matters and overcome your fear of failure.

4 min readWork & Productivity

Joshua McDonaldJan 6, 2020

Complected

I just finished reading a book that was recommended to me by a coworker. The book, titled the Unicorn Project by Gene Kim, outlines…

12 min readLeadership & Organizations

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Your AI Model Has a Retirement Date

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Latest

Fewer Wrong Exits: The Wayfinding Method Behind DC Metro’s New Signs

Your First Month Leading a New Team, Week by Week

Agents Raise the Price of a Big Team

The Human in the Loop Is Approving Everything

Alchemy, Read by Someone Who Manages Engineers

Four Hours to Build, Five Years to Own

Everything Says Urgent, So Stop Sorting on Arrival

A Third of Feedback Makes Performance Worse

The Org Chart, the Tube Map, and Models That Are Wrong on Purpose

Only Variety Can Absorb Variety

AI Made Writing Code Nearly Free. Reviewing It Got 91 Percent Slower.

Being Wrong in Public

The cost of changing your mind depends on two things: how fast feedback arrives, and how much got…

Every Improvement Made No Difference

Adding People Reduced Output

Everything Is 90 Percent Done

Amdahl’s Law for Org Charts

What “Open Weight” Actually Means

Ask Your Dashboard What It Reads When Nothing Changed

You Can’t Compress What You Can’t Grade

I Built a Prompt Compressor. The Most Useful Thing It Found Was Nothing

You do need pronunciation files across the languages, account for speed variances - but you should…

Let the Expensive Model Write the Instructions

Who Reviews the Reasoning?

Do We Still Need the Sprint?

The Preflight Check for Distributed Systems

What 10²⁶ Actually Means

How an Export Control Rule Reaches an AI Model Running in a US Data Center

Claude Skipped Idempotency Because I Never Asked. So I Made Asking Unnecessary.

Why system design matters more as AI makes building faster

robots.txt Told Crawlers Where to Stop. llms.txt Tells Agents Where to Go

What a Jar of Peanut Butter Teaches About Agent Skill Security

What an Agent Skill Is, and How to Write One

EARS, Fifteen Years On: The Requirements Format Built for the Agent Era

MCP, Plainly

Teaching Probability Through Soccer: Built With Claude Code

The Quiet Repricing of AI Coding Tools

Coordinating Parallel Engineering Work With Claude

Just the Road: Notes on perspective in an industry being rebuilt under our feet.

The Little Blue Menu and What It Already Knows About AI

Six Prompts for Reading an Engineering Roadmap

Running a Small Team on a Big Project: Spec-Driven Development with Claude Code

I Used AI to Audit 7,200 Hospital Price Files. It Found Something the Code Missed.

The Prototype Got Cheap. The Product Didn’t.

A Spring Break Commute, Five Dollars, and the State of Multilingual Text-to-Speech

You Don’t Have to Write Code to Need a CLAUDE.md

Day 1

When You Can Build Anything, How Do You Decide What to Build?

Spec Driven Development and Managing software projects in 2026 using AI development tools

Building a Local AI Coding Assistant: VS Code + Ollama + Small Language Models

Nudge Theory Revisited: Writing Tickets for Humans and Machines

Your Team Doesn’t Need Well-Rounded Engineers. It Needs a Well-Rounded Team.

Purpose Is Everything

I Built a DC Transit Companion with AI on My Commute using my iPhone. Here’s what I learned.

The Best Engineering Leaders I’ve Seen All Have One Thing in Common: They’re Calm When Everything…

How AI Dev Tools Can Turn Your Cloud Bill Into Useful Insights

When Every Engineer Is a Manager

n(n−1)/2

If Your Career Were a Product, Would Anyone Invest?

Why Every Engineering Team Needs a Monthly Business Review

Understanding Directed Acyclic Graphs (DAGs) with a Baseball Analogy

The Efficiency Illusion: Why Your AI Strategy is Accelerating Inefficiency, and How to Pivot to…

What a 15th-century lawsuit and a lead letter ‘A’ can teach us about the age of AI

Build Your Own AI General Contractor: A Practical Simulation Implementing Deterministic Guardrails…

Stop Hiring “Handyman” AI: Why Production Requires a General Contractor

What the Longest Escalator in the Western Hemisphere Teaches Us About AI

Why Your AI Sounds Like a Corporate HR Department (And How to Fix It)

Why Your AI Feels Slow: The “Baggage Claim” Theory of Latency

Why AI Forgot Your Name: The “Vanishing Whiteboard” Theory

How to Stop AI Hallucinations by Teaching It to Say “I Don’t Know”

Why Most AI Models Can't Count the Letter "R" in Strawberry

Stop Treating AI Like a Brain. Treat It Like a Stadium.

What a trip to the supermarket can teach you about writing security tickets that engineers actually…

Engineering Teams in the Age of Agentic AI

Reading list

Crockpot Pumpkin and Chorizo Chili