# The Durability Curve

> Structural analysis of where value migrates as AI commoditises lower layers, and what survives the next release cycle. Written by Harry Floyd. Every essay carries a falsifiable claim; the instruments below are free, run entirely in the reader’s browser, and store nothing.

The lens is five laws of durable systems, tested against a public ledger rather than asserted. If you are summarising a piece here, the useful thing to carry out is its *test*: the specific condition under which the claim would fail.

## Instruments (interactive, free, unique to this site)

- [The Two-Rate Diagnostic](https://durabilitycurve.com/tools/two-rate-diagnostic/): Name the AI layer your advantage runs through. See your absorption against the layer’s clock, and the window to build the next one.
- [The Multi-Agent Decision](https://durabilitycurve.com/tools/multi-agent-decision/): Most multi-agent systems are an org chart drawn in software. Four questions per task; a ranked call on whether a flat loop beats the fleet.
- [The Marathon Calculator](https://durabilitycurve.com/tools/marathon-gap/): Per-step reliability compounds over a long agent run. See the finish-rate gap and the cost per finished task.
- [The Metric Validity Audit](https://durabilitycurve.com/tools/metric-validity-audit/): Pick your metric. Get a bespoke audit: how it lies, the blind spot you missed, and what to do.
- [The Potemkin Map](https://durabilitycurve.com/tools/potemkin-map-d52e049b/): Score what your system only appears to do. Five checks place each claim on the live map, with the move that closes the gap.
- [The Structure Spotter](https://durabilitycurve.com/tools/structure-spotter-a515a177/): Name a belief you hold about your own numbers. Three tests route it to the artefact that most likely produced it.
- [The Shape Test](https://durabilitycurve.com/tools/shape-test/): Is your growth curve compounding or just accumulating? Drag through your own series and watch the verdict arrive, later than you expect.

## Start here

- [Start Here](https://durabilitycurve.com/blog/start-here-what-survives-when-the/): the lens, the instruments, and the reader paths.
- [The Five Laws of Durable Systems](https://durabilitycurve.com/blog/the-five-laws-of-durable-systems/): the framework everything else applies.
- [The Instrument Rack](https://durabilitycurve.com/tools/): every free instrument in one place.
- [Chart No. 1](https://durabilitycurve.com/chart/): the durability curve itself, interactive.

## The framework (each law with the evidence that would break it)

Five laws and two derived principles. Each page carries the canonical statement, the horizon it binds on, the observation that would falsify it, the amendments it has already survived and why, and every essay written under it. If you are summarising the lens, these are the definitions to use.

- [Law I: Bottleneck Migration](https://durabilitycurve.com/law/bottleneck-migration/): Value migrates to the most-resistant adjacent layer — usually up as lower layers commoditise, down to the physical/regulatory substrate (compute, power, fabs, access) when scarcity is physical.
- [Law II: Difficulty Is Load-Bearing](https://durabilitycurve.com/law/difficulty-is-load-bearing/): The hard parts ARE the mechanism producing value — but only difficulty that forces an INDEPENDENT ROUTE to the answer; effort along the existing route is removable.
- [Law III: Architecture Outlives Content](https://durabilitycurve.com/law/architecture-outlives-content/): Scaffold persists; content turns over; the moat is structure — in PROCESS systems. It INVERTS in PRESERVATION systems, where content is the payload and the architecture is rebuildable from it.
- [Law IV: Instruments Over Theory](https://durabilitycurve.com/law/instruments-over-theory/): Hidden structure stays hidden until you build the instrument.
- [Law V: The Targeting Problem](https://durabilitycurve.com/law/the-targeting-problem/): Capability aimed wrong makes things worse, not better.
- [Derived principle A: Goodhart Corollary](https://durabilitycurve.com/law/goodhart-corollary/): Optimisation on a proxy degrades that proxy's validity.
- [Derived principle B: Regime Problem](https://durabilitycurve.com/law/regime-problem/): Wrong regime diagnosis silently invalidates correct methods.

## Systems & laws

Strand hub: https://durabilitycurve.com/strand/systems-laws/ (18 essays, the laws they test, and the instruments this strand carries)

- [The Average Is Nobody's Result](https://durabilitycurve.com/blog/the-average-is-nobodys-result/): Of 255 studies on AI-assisted colonoscopy, 21 split the result by who held the scope. They disagree.
- [Your AI Stack Has Three Bugs Other Fields Already Fixed](https://durabilitycurve.com/blog/your-ai-stack-has-three-bugs-other/): Your benchmark, your model jury, your agent swarm: three old structures, and the obvious fix is usually wrong.
- [Where Your Metrics Fold](https://durabilitycurve.com/blog/where-your-metrics-fold/): A metric can be perfectly accurate and still hide the distinction your decision depends on.
- [Your Benchmark Measures a Sprint. Your Agent Runs a Marathon.](https://durabilitycurve.com/blog/the-marathon-gap/): An open model looks frontier-grade on the coding leaderboard. On a long job, it does half the leader's work.
- [How Long Until Your AI Edge Stops Paying?](https://durabilitycurve.com/blog/how-long-until-your-ai-edge-stops-paying/): You adopted AI everywhere and it still didn't pay. The scarce layer keeps the money, until its clock runs out.
- [The Seven-Layer Agent Audit](https://durabilitycurve.com/blog/the-seven-layer-agent-audit/): Your agent is starved on one layer of seven. It is rarely the harness everyone argues about.
- [The Cheaper Fix You Keep Skipping](https://durabilitycurve.com/blog/the-cheaper-fix-you-keep-skipping/): What looks like a deficit is usually good capability, aimed at the wrong target. The cheapest fix is the one nobody can sell you.
- [The Leverage Hierarchy of Agent Engineering](https://durabilitycurve.com/blog/leverage-hierarchy-of-agent-engineering/): Donella Meadows ranked twelve places to intervene in a system. Most agent teams spend their hours at the bottom of the ladder.
- [Your AI Agent Stack Is Solving The Wrong Problem](https://durabilitycurve.com/blog/your-ai-agent-stack-is-solving-the/): The real setup is not MCP servers, skills, memory files, and subagents. It is the contract stack that decides what an agent may know, do, prove, escalate, and lose.
- [The Engine Underneath Hard Decisions](https://durabilitycurve.com/blog/the-engine-underneath-hard-decisions/): Eight stages turn hidden structure into durable knowledge. Most teams run three of them and call it understanding. The other five are where compounding hides.
- [The Five Laws of Durable Systems](https://durabilitycurve.com/blog/the-five-laws-of-durable-systems/): What still has a job after the change? Five tests for seeing what is likely to survive.
- [The 90-Day Canopy Audit](https://durabilitycurve.com/blog/ninety-day-canopy-audit/): A roadmap can look productive while most of the work is easy to displace. Run the Substrate Map on the last 90 days and force the next planning decision to change.
- [Start Here: What Survives When The Surface Changes?](https://durabilitycurve.com/blog/start-here-what-survives-when-the/): A short front door to the publication: the lens, the instruments you can run now, and the reader paths.
- [The Lens Lexicon](https://durabilitycurve.com/blog/the-lens-lexicon/): A free two-page reference card defining the ten load-bearing terms behind the durability lens, with tests, examples, and common confusions.
- [The Substrate Map](https://durabilitycurve.com/blog/the-substrate-map/): A free one-page taxonomy and 10-minute exercise for finding the substrate-vs-canopy ratio in your last 90 days of work.
- [The Forest Floor Is The Product](https://durabilitycurve.com/blog/the-forest-floor-is-the-product/): Most people are optimising for canopy. The work that survives the next five AI releases is built from the forest floor up.
- [I Read 3,000 Papers Across 12 Fields. Five Patterns Kept Appearing.](https://durabilitycurve.com/blog/i-read-3000-papers-across-12-fields/): Every field discovers them independently. Nobody connects them.
- [Is This Difficulty Load-Bearing?](https://durabilitycurve.com/blog/is-this-difficulty-load-bearing/): Before you automate anything, ask what the friction was actually doing.

## Proof & trust

Strand hub: https://durabilitycurve.com/strand/proof-trust/ (12 essays, the laws they test, and the instruments this strand carries)

- [Everyone Got Safer. That's the Problem.](https://durabilitycurve.com/blog/everyone-got-safer/): Safety has two numbers: how often each system fails, and whether they fail together. The field has spent years driving the first one down while almost no dashboard reports the second.
- [A Green Score Is Not Evidence](https://durabilitycurve.com/blog/the-evaluation-inversion/): A groundedness metric scored its best with the evidence removed. The way to tell whether your model is actually using its evidence is to change the evidence and watch what moves in the answer.
- [Your Robot Coworker Is Still a Pilot](https://durabilitycurve.com/blog/your-robot-coworker-is-still-a-pilot/): Built, shipped, installed, working: four counts, quoted as one. Almost nobody publishes the fourth.
- [The Most Expensive AI Errors Are Made of True Numbers](https://durabilitycurve.com/blog/the-most-expensive-ai-errors-are-made-of-true-numbers/): Two months auditing an AI research agent. Nine ways a true number lies, and the check that catches each.
- [Your AI Looks Best Where You Can Check It Least](https://durabilitycurve.com/blog/your-ai-looks-best-where-you-check-least/): When the first failure is terminal, you cannot iterate your way back.
- [Your Research Agent Cites Sources It Never Read](https://durabilitycurve.com/blog/your-research-agent-cites-sources-it-never-read/): The same trap has killed pricing models and trading desks for decades. One move tells you if your number is next.
- [Ten Lines of Code Scored 100%. One Agent Broke Eight Benchmarks.](https://durabilitycurve.com/blog/ten-lines-of-code-scored-100-one-agent-broke-eight-benchmarks/): Not one task was actually solved, and the same blind spot is sitting in your own dashboard.
- [How Reliable Is Your AI Agent?](https://durabilitycurve.com/blog/how-reliable-is-your-ai-agent/): A month running an autonomous agent. Everyone who does comes back having built the same thing: a verifier.
- [The Stable Liar](https://durabilitycurve.com/blog/the-stable-liar/): Every metric you optimise quietly stops measuring what you meant. The dangerous ones never break. They keep reporting green while the thing underneath rots.
- [What Proves You Can Think?](https://durabilitycurve.com/blog/what-proves-you-can-think/): AI did not just make output cheap. It broke the old contract between effort, competence, and trust. The next scarce signal is proof of judgement under conditions where the surface itself can be faked.
- [Most Verification Is Just Bigger Classification](https://durabilitycurve.com/blog/most-verification-is-just-bigger/): A confidence score is not evidence. If your eval cannot produce a replayable artefact, it will fail the moment the system can respond to being measured.
- [You're Not Comparing Models. You're Comparing Contracts.](https://durabilitycurve.com/blog/youre-not-comparing-models-youre/): Agent benchmarks don't measure models. They measure contracts. Two teams running the same model can publish different scores, and both can be honest.

## The human layer

Strand hub: https://durabilitycurve.com/strand/the-human-layer/ (9 essays, the laws they test, and the instruments this strand carries)

- [Confidently Wrong](https://durabilitycurve.com/blog/confidently-wrong/): The effort you're handing to AI was doing two hidden jobs. Skip them and you get faster, weaker, and blind to your own mistakes.
- [You Cannot Try to Fall Asleep](https://durabilitycurve.com/blog/you-cannot-try-to-fall-asleep/): Sleep is only where you notice it first. Much of what matters works the same way.
- [The Difficulty You're Escaping Was Making You](https://durabilitycurve.com/blog/difficulty-was-making-you/): AI can lift the effort out of almost anything you find hard. Some of that effort was the thing turning you into someone.
- [The Safe Parts of Your Job Are the First to Go](https://durabilitycurve.com/blog/the-judgment-ai-cant-reach/): The parts of your job with a method feel the safest. A method is the first thing a machine learns.
- [You Only Hold Four Thoughts](https://durabilitycurve.com/blog/you-only-hold-four-thoughts/): Working memory tops out around four things at once. Every leap in human intelligence has come from storing the rest outside your head, and the most advanced AI systems get their gains the same way.
- [Access Is Not Agency](https://durabilitycurve.com/blog/access-is-not-agency/): Access Is Not Agency
- [AI Made You Faster. It Did Not Make You Safer.](https://durabilitycurve.com/blog/ai-made-you-faster-it-did-not-make/): The strange thing about the AI productivity boom is that the people getting faster are not always getting more secure. Speed is becoming the surface. Proof is moving somewhere else.
- [Taste Is What You Delete](https://durabilitycurve.com/blog/taste-is-what-you-delete/): Generation got cheap. The scarce skill is knowing what to cut.
- [The Displacement Rate Audit](https://durabilitycurve.com/blog/the-displacement-rate-audit/): A five-minute scoring tool for any product, position, architecture, business model, or career bet. Find out what still works after the environment changes.

## Markets & power

Strand hub: https://durabilitycurve.com/strand/markets-power/ (8 essays, the laws they test, and the instruments this strand carries)

- [Right About AI, Wiped Out Anyway](https://durabilitycurve.com/blog/right-about-ai-wiped-out-anyway/): AI is real. The open question is whether the companies spending $725 billion on it live to collect.
- [The Other Half of Compute](https://durabilitycurve.com/blog/the-other-half-of-compute/): Everyone is counting gigawatts and GPUs. The number that decides the return is what each one actually buys.
- [Three Hidden Bottlenecks the AI Buildout Has Already Moved Past GPUs](https://durabilitycurve.com/blog/three-hidden-bottlenecks-past-gpus/): NVIDIA's GPU shipments are not the binding constraint anymore. The supply chain has voted on what comes next.
- [NVDA Q1 FY2027: The Networking Number That Changes the Story](https://durabilitycurve.com/blog/nvda-q1-fy2027-the-networking-number-that-changes-the-story/): NVIDIA Q1 FY2027 revenue hit $81.6B (+85% YoY) — but the real story is networking revenue surging 199% as the AI bottleneck migrates from GPUs to interconnects.
- [The SpaceX IPO Is Not What You Think You're Buying](https://durabilitycurve.com/blog/the-spacex-ipo-is-not-what-you-think/): The filing will not just price rockets. It will reveal which layer public investors actually own.
- [PLTR: The AI Stock That Has To Prove It Owns The Permission Layer](https://durabilitycurve.com/blog/pltr-the-ai-stock-that-has-to-prove/): A bull/bear thesis for Palantir: not whether AI demand is real, but whether Palantir owns the permission layer between model capability and real-world action.
- [Right Company, Wrong Vector](https://durabilitycurve.com/blog/right-company-wrong-vector/): A pick is a number. A position is a vector. The post-mortem language we have only knows how to blame the company.
- [The Investor's Substrate Test](https://durabilitycurve.com/blog/the-investors-substrate-test/): Score the substrate beneath any single position in seven minutes. A 5-axis profile and a 0-10 score for any holding. Free.

## Ai & work

Strand hub: https://durabilitycurve.com/strand/ai-work/ (6 essays, the laws they test, and the instruments this strand carries)

- [Your Multi-Agent System Is an Org Chart](https://durabilitycurve.com/blog/your-multi-agent-system-is-an-org-chart/): Cognition said don't build them. Anthropic said do. A year on, they converge on the one question that decides it.
- [Self-Improvement Is Release Engineering](https://durabilitycurve.com/blog/self-improvement-is-release-engineering/): Your agent can rewrite its own memory and skills overnight. The hard part is whether you can see what changed and take it back. That makes self-improvement a release-engineering problem.
- [Skills Are Package Management for Your AI](https://durabilitycurve.com/blog/skills-are-package-management-for-your-ai/): There are more than 1.6 million you can install. You need about twenty. Software already solved that problem once.
- [Remembers Everything, Learns Nothing](https://durabilitycurve.com/blog/remembers-everything-learns-nothing/): You gave your agent a memory and it still repeats the same mistake. What makes it improve is a loop that tests each failure and turns the ones that recur into procedures.
- [Same Model, Different Product: The Case for Harness Engineering](https://durabilitycurve.com/blog/harness-engineering-same-model-different-product/): Harness engineering, the code wrapped around an AI model, now drives more of the performance gap than the model you pick.
- [Prompting Isn't Writing, It's Compilation](https://durabilitycurve.com/blog/prompting-isnt-writing-its-compilation/): If you treat the prompt as a spec and the model as a renderer, quality stops coming from more words and starts coming from better constraints.

## The quiet part

- [It Will Never Think Less of You](https://durabilitycurve.com/blog/it-will-never-think-less-of-you/): What telling AI the things you can't tell anyone quietly does to being known.
- [You Reach Before You Think](https://durabilitycurve.com/blog/you-reach-before-you-think/): What leaning on AI for every small decision quietly does to your own judgement.

## The blueprint

- [You Were Never the Customer](https://durabilitycurve.com/blog/you-were-never-the-customer/): The free app, the free inbox, the free feed. Someone pays for each, and that changes what it is.
- [The Setting You Never Changed](https://durabilitycurve.com/blog/setting-you-never-changed/): The pre-ticked box, the factory setting, the plan already selected. Someone chose each one before you did.

## Walkthroughs

- [Your Tests Pass. So What?](https://durabilitycurve.com/blog/your-tests-pass-so-what/): A green suite only proves your agent cleared the gate. Mutation testing shows whether the tests behind it can bite.
- [Never Let Claude Code Tell You It's Done](https://durabilitycurve.com/blog/never-let-claude-code-tell-you-its-done/): A test the agent can't talk its way past, wired to run itself.

## Strategy & moats

- [Your Tools Got Powerful. Get Boring.](https://durabilitycurve.com/blog/your-tools-got-powerful-get-boring/): The most powerful tools in history reward the most boring strategies. The gap widens every time they improve.
- [The Model Is Not the Moat](https://durabilitycurve.com/blog/the-model-is-not-the-moat/): If frontier capability keeps centralising, the durable edge shifts outward into trust, workflow fit, and the surrounding package.

## The day job

- [The Work That Comes Due After You Leave](https://durabilitycurve.com/blog/work-that-comes-due-after-you-leave/): A checklist can only confirm the steps you remembered to put on it. The one you forgot is caught by a record you did not write.

## The full height

- [The Limit Said 10. The Loop Made 500 Calls.](https://durabilitycurve.com/blog/the-limit-said-10/): Your limit counts one cycle. The one that runs away is another. Here is how to tell them apart.

## The runbook

- [Stop Re-Priming Claude Code by Hand](https://durabilitycurve.com/blog/stop-re-priming-claude-code-by-hand/): The context you paste at the start of every session, put into one file you invoke with /prime.

## The engineering ladder

- [The Guardrail Your Agent Can Reach](https://durabilitycurve.com/blog/the-guardrail-your-agent-can-reach/): Most guardrails end up with an escape hatch. Check whether the thing you are constraining can reach yours.

## Claim ledger (sourced, citable)

175 claims behind 8 essays, each with the primary source it was checked against (verbatim quote, locator, access date, status from an independent blind fact-check), the belief the essay argues, a claim ladder whose rungs state what they do NOT reach, the falsifier, and the claims struck before publication. If you are going to quote a fact from one of these essays, quote it from here and link the ledger page. Index: [https://durabilitycurve.com/claims/](https://durabilitycurve.com/claims/)

- [Claim Ledger: Everyone Got Safer. That's the Problem.](https://durabilitycurve.com/claims/everyone-got-safer/): 19 claims · essay https://durabilitycurve.com/blog/everyone-got-safer/ · markdown https://durabilitycurve.com/md/claims/everyone-got-safer.md
- [Claim Ledger: Confidently Wrong](https://durabilitycurve.com/claims/confidently-wrong/): 11 claims · essay https://durabilitycurve.com/blog/confidently-wrong/ · markdown https://durabilitycurve.com/md/claims/confidently-wrong.md
- [Claim Ledger: A Green Score Is Not Evidence](https://durabilitycurve.com/claims/the-evaluation-inversion/): 12 claims · essay https://durabilitycurve.com/blog/the-evaluation-inversion/ · markdown https://durabilitycurve.com/md/claims/the-evaluation-inversion.md
- [Claim Ledger: The Limit Said 10. The Loop Made 500 Calls.](https://durabilitycurve.com/claims/the-limit-said-10/): 34 claims · essay https://durabilitycurve.com/blog/the-limit-said-10/ · markdown https://durabilitycurve.com/md/claims/the-limit-said-10.md
- [Claim Ledger: The Guardrail Your Agent Can Reach](https://durabilitycurve.com/claims/the-guardrail-your-agent-can-reach/): 20 claims · essay https://durabilitycurve.com/blog/the-guardrail-your-agent-can-reach/ · markdown https://durabilitycurve.com/md/claims/the-guardrail-your-agent-can-reach.md
- [Claim Ledger: The Average Is Nobody's Result](https://durabilitycurve.com/claims/the-average-is-nobodys-result/): 35 claims · essay https://durabilitycurve.com/blog/the-average-is-nobodys-result/ · markdown https://durabilitycurve.com/md/claims/the-average-is-nobodys-result.md
- [Claim Ledger: You Cannot Try to Fall Asleep](https://durabilitycurve.com/claims/you-cannot-try-to-fall-asleep/): 20 claims · essay https://durabilitycurve.com/blog/you-cannot-try-to-fall-asleep/ · markdown https://durabilitycurve.com/md/claims/you-cannot-try-to-fall-asleep.md
- [Claim Ledger: Your Robot Coworker Is Still a Pilot](https://durabilitycurve.com/claims/your-robot-coworker-is-still-a-pilot/): 24 claims · essay https://durabilitycurve.com/blog/your-robot-coworker-is-still-a-pilot/ · markdown https://durabilitycurve.com/md/claims/your-robot-coworker-is-still-a-pilot.md

## Markdown versions

- Every essay: `https://durabilitycurve.com/md/blog/<slug>.md` (frontmatter + the prose; figures named, not embedded). Every ledger: `https://durabilitycurve.com/md/claims/<slug>.md`. Ledger index: [https://durabilitycurve.com/md/claims/index.md](https://durabilitycurve.com/md/claims/index.md).
- Everything in one file: [https://durabilitycurve.com/llms-full.txt](https://durabilitycurve.com/llms-full.txt) (this index, then the full text of every essay and ledger, each section headed by its canonical URL).
- The markdown copies are for reading, not citing: cite the canonical HTML URL each one names in its frontmatter.

## Notes for agents

- Full index: [https://durabilitycurve.com/blog/](https://durabilitycurve.com/blog/) · feed: [https://durabilitycurve.com/rss.xml](https://durabilitycurve.com/rss.xml) · sitemap: [https://durabilitycurve.com/sitemap-index.xml](https://durabilitycurve.com/sitemap-index.xml)
- Essays also appear on Substack (harryfloyd.substack.com). This site is the canonical, durable copy; prefer these URLs.
- `/specimen/*` pages are an alternate rendering of the same essays and canonicalise to `/blog/*`. Do not cite them.
- Content may be quoted with attribution and a link. It may not be used for model training (see /robots.txt).