The build-exit CTO experiment
One new term, one definition, and a dated prediction about whether answer engines name its author.
The answer first. On 2026-10-09 Stefan Coetzee defined a new term, build-exit CTO, on machinebehavior.io/your-next-cto. Before that page went live he wrote and hashed a prediction: on 2026-11-30, at least 2 of ChatGPT search, Perplexity and Google AI Overviews name Stefan Coetzee for the term. A control query predicts the opposite result for a term other providers already hold. The result goes on this page whichever way it lands.
The term
A build-exit CTO builds the platform and the practice to run it, hands both to a named owner inside the company, and leaves on a date set at the start.
On 2026-10-09 no page used or defined the term. Searches for "build-exit CTO" and "build exit CTO" through a self-hosted SearXNG instance returned pages about building a company for a sale and none that uses the term; that day the instance had yandex, mojeek and zapmeta answering, and google cse, brave, gmx and duckduckgo unavailable. The exact-match domains buildexitcto.com, buildexitcto.io and buildexitcto.de were unregistered (whois, 2026-10-09).
The prediction
The full text is predictions/build-exit-cto-aeo-2026-10-09.txt, sha256 b990c08bcf47c3b8a09d79da894201e07b3e22bcc3b4afa2830098e876bcea74, listed in predictions/HASHES.txt. The deploy gate checks that hash on every push, so the file cannot change without a failed run.
- P1. On 2026-11-30, at least 2 of the 3 engines name Stefan Coetzee for the term.
- P2. On 2026-11-30, at least 1 of the 3 engines cites a machinebehavior.io URL for the term.
- P3, control. On 2026-11-30, none of the 3 engines names Stefan Coetzee for the query "fractional CTO Germany".
Why these numbers
An answer engine that retrieves from a live web index can only return pages that exist for a query. For an empty term, the first clear definition is most of what there is to return. That mechanism is what P1 tests. The bar is 2 engines out of 3 because Google shows AI Overviews for some queries and not others, and a new low-volume phrase may get none. The date, 2026-11-30, is seven weeks after publication, which covers several crawl cycles for a site that publishes a sitemap and allows every crawler in robots.txt.
P3 separates filling an empty query from standing on a contested one. "fractional CTO Germany" has established providers. If an engine names Stefan Coetzee there, the result goes on this page with an explanation, and it does not count toward P1.
Probe plan
| Item | Setting |
|---|---|
| Engines | ChatGPT search, Perplexity, Google AI Overviews |
| Queries | Q1 "build-exit CTO"; Q2 "What is a build-exit CTO?"; control "fractional CTO Germany" |
| Run | One query in a fresh session, logged out or on a measurement account with no history, English, from Germany; three runs per engine and query on each probe date |
| Names him | The answer text to Q1 or Q2 contains "Stefan Coetzee" in at least 2 of the 3 runs |
| Cites the site | At least one run lists a machinebehavior.io URL as a source |
| No AI Overview | Counts as not naming him on that date |
| Dates | Weekly on Mondays from 2026-10-12, final reading on 2026-11-30 |
| Log | Each probe date added to this page: engine, query, runs that name him, URLs cited |
Baseline, 2026-10-09
| Probe | Result |
|---|---|
| Web search for "build-exit CTO" and "build exit CTO" (SearXNG; yandex, mojeek, zapmeta answering) | No page uses or defines the term |
| Exact-match domains buildexitcto.com, .io, .de | Unregistered |
| ChatGPT search, Perplexity, Google AI Overviews | Not probed before publication. No manual run was made and no reading from Search Console or Bing was recorded, so there is no pre-publication reading for the three engines |
Measurement status
Google Search Console and Bing Webmaster Tools are set up for machinebehavior.io. The Search Console verification record is in DNS (checked 2026-10-09), the sitemap was submitted on 2026-10-07, and Bing imported the site from Search Console. No reading from Search Console's Generative AI report or from Bing's AI Performance report is recorded for this experiment yet. A Perplexity API probe is not set up; that is Stefan Coetzee's decision. Neither report records answer text or covers ChatGPT search, so those readings are taken by hand in a browser and logged on this page. What each report counts and leaves out is on AIEO measurement.
Correction, 2026-10-09. The prediction file says the measurement accounts were not set up. That sentence was wrong when it was written: Search Console and Bing were set up on 2026-10-07. The file stays as hashed, and this page carries the correction.
What the experiment does not do
- No paid press releases and no invented events.
- No exact-match domains.
- No hidden text and no text addressed to models.
- No claim that the term is in wide use. It has one source, this site, and the page says so.
The inputs are the pages under /your-next-cto/, the article "Who should your next CTO be?" once it is published, and links Stefan Coetzee adds from his own profiles.
What refutes it
P1 is refuted if fewer than 2 engines name Stefan Coetzee for the term on 2026-11-30. P2 is refuted if no engine cites a machinebehavior.io URL for it. A refuted prediction stays on this page next to its hash.