ChatGPT’s agent mode does a task inside a session: it browses, clicks, fills forms and reports back while you watch. It is genuinely useful for a one-off. What it does not leave behind is the thing itself: a repository, a running app, a domain, a schedule, a spending limit. An agent that ships produces those, prints the price under each step, and asks you before it does anything you cannot undo.
The question people ask is “which agent is smarter.” The question that decides whether you get value is “what is left when it stops.”
What agent mode is good at
Hand it a task that lives in a browser and it will do it: research a list, compare prices, fill in a form, pull a summary together. It shows its work as it goes, and you can take over. For a task you need done once, today, that is exactly right, and there is no reason to use anything heavier.
Where it ends
The output is a message. If the task was “build me a quote calculator,” you get code in a reply, and now you need somewhere to put it, a way to run it, a domain, and someone to fix it when it breaks next month. The agent did the interesting part and left you the operational part, which is most of the work.
Two other things end with the session. There is no schedule: it cannot run again tomorrow at seven without you starting it. And there is no budget of the kind an accountant would recognise: a subscription is a ceiling on your access, not a ceiling on what a runaway loop can consume inside it.
What an agent that ships leaves behind
- A repository. The code is committed to a git repo you own, with history. Take it anywhere.
- A running thing. Hosting is included; the app is live at a real address, and at your own domain if you have one.
- A schedule. Agents can run on a cadence, and each run reports what it did and what it cost.
- A budget that stops the loop. The limit is checked before the next step, not read off the invoice.
- A price on every answer. Down to the fraction of a cent, per step, per model. Which is how we learned that the cheapest model wins most jobs.
- An approval before anything irreversible. Publishing, sending, charging, deleting: proposed by the agent, decided by you.
Use both, for different things
Agent mode for the one-off you want to watch. An agent that ships for anything you will still want next week. The honest test is to ask, before you start, “will I need this to exist tomorrow?” If yes, pick the tool that leaves something behind.
If you want to see the difference in five minutes, start from a template, tell the agent whose business it is, and open the address it gives you back.
The full comparison What it costs
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Working notes on building with AI, with the measurements and the bills attached. Sent when there is something worth sending, which is not weekly.
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Keep what the agent makes.
A repo, a running app, a domain, a schedule, and a budget. Not a transcript.
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