PROCESS

Here is How to Build

Design

Sub

Parts drift

Everything in this volume so far has been done at one moment. The pieces were chosen, cut clean, placed by need, given one result each, and joined at seams that carry only that result. On the day it is finished, the design is sound. But a process does not stand still after it is designed. New work arrives: a new product, a new channel, a new rule. Volumes rise in one place and fall in another. Teams are reorganised, systems replaced, suppliers changed. Every one of those changes lands somewhere in the process, and over time it moves the parts.

It rarely lands where it belongs. A change goes where it is easiest to put: into whichever part is nearest, whichever team is closest to the request, whichever system already touches something similar. A new payment method is added inside the part that handles payments, because that is where payments live, even if its flow is quite different. A new check is added to the end of whatever part runs just before the risk appears. Each addition is reasonable on its own. Nobody decides to blur the parts. But change after change, a part grows a second job, two neighbours start leaning on each other, a part stays in place long after its reason has gone. That slow movement, accumulated rather than chosen, is drift.

So a part is never cut once and for all. A clean cut is right for the work as it was when the cut was made, and the work does not stay as it was. This is not a failure of the first design, and it is not a reason to cut less carefully at the start. It is simply the nature of a living process: the cut that fitted the work will, sooner or later, stop fitting it. The designer's job does not end with the first cut. It continues as the work moves, by noticing when the parts have drifted and cutting them again.

The highest possible standard is to treat every cut as right for the work as it was, not for all time, expecting the parts to drift as changes accumulate in whichever part is nearest, and keeping the design under watch so that drift is noticed and answered rather than left to blur the parts unseen.

Key Takeaway: A clean design is sound on the day it is finished, but the process keeps changing: new work, shifting volumes, new teams and systems. Each change lands somewhere, and rarely where it belongs; it goes into whichever part is nearest. Each addition is reasonable, nobody decides to blur the parts, yet over time a part grows a second job, neighbours lean on each other, and parts outlive their reason. That accumulated movement is drift. A cut is right for the work as it was, and the work moves, so the designer's job continues: notice when the parts have drifted, and cut again.

A clean cut is right for the work as it was; as changes accumulate, the parts drift, and the design must be cut again.

MarvinPro · PROCESS · Here is How to Build · Design · Sub · Discipline 7: Drift · Section: Parts drift

MarvinPro | October 2026

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The signs of drift

Drift is slow, so it is easy to miss. No single change looks like a problem, and by the time the process is plainly struggling, the parts may have drifted a long way from where they were cut. So drift has to be read, not waited for. And the signs to read it by are already in hand, because they are the same signs that told you a cut was clean in the first place. A part that has drifted is a part that now fails the tests it once passed.

Read them one by one. The name: a clean part could be named in one phrase, and a drifted part needs an "and" again, because it has grown a second job. The result: a clean part answered for one checkable result, and a drifted part's result can no longer be stated in one line, or has quietly split into two. The seam: a clean seam carried only the result, and a drifted seam has thickened, with more and more crossing it, the neighbours asking each other questions, passing detail back and forth, leaning on each other's insides. The gaps: work that keeps landing between two parts, handled by whoever notices, is a sign that the parts no longer cover the whole between them. And the leftovers: a part whose result now appears nowhere in the whole, still running, still costing, is a sign that the work moved on and the part did not.

These signs are cheap to check, and they should be checked regularly, not only when something breaks. A short review of each part against its name, its result and its seams, at a steady rhythm or whenever a significant change lands, catches drift while it is still small. It also gives the people who run the process a plain language for what they feel: not "this part is a mess", but "this part needs an 'and' now", or "this seam has thickened". Drift named early is cheap to correct. Drift found late, when the process is struggling, has usually spread into several parts at once.

The highest possible standard is to read drift from the same signs that confirmed the cut, checking each part regularly against its one-phrase name, its one-line result and the thinness of its seams, and watching for gaps and leftovers, so drift is caught while it is small rather than discovered when the process is already struggling.

Key Takeaway: Drift is slow and easy to miss, so it must be read, not waited for. The signs are the ones that confirmed the cut: a part's name needs an "and" again; its result no longer fits in one line; a seam has thickened, with neighbours leaning on each other's insides; work keeps landing in the gap between two parts; a part's result appears nowhere in the whole any more. Check these regularly, and whenever a significant change lands, not only when something breaks. They also give people plain words for what they feel. Drift named early is cheap to correct; drift found late has usually spread.

Read drift from the signs that confirmed the cut: the name, the result, the seam, the gaps and the leftovers, checked regularly, not only when something breaks.

MarvinPro · PROCESS · Here is How to Build · Design · Sub · Discipline 7: Drift · Section: The signs of drift

MarvinPro | October 2026

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Split, merge, retire

When the signs show drift, there are three ways to answer it, and each answers a particular sign. The first is to split. A part that has grown a second job, whose name needs an "and" and whose result has two halves, is cut into two parts, each with its own name and its own result. The split follows the same rule as any clean cut: it goes at the natural joint between the two jobs, where the flows genuinely differ, not wherever is convenient. The second is to merge. Two parts whose seam has thickened, that now talk to each other constantly, are telling you what the thick seam told you in the third discipline: the line between them is in the wrong place, and the things on both sides belong together. So they are joined into one part, with one result. The third is to retire. A part whose result now serves nothing in the whole (a check that outlived its reason, a step for a channel no one uses) is removed, after finding out what it was for and confirming nothing still needs it.

Each of these is a real change, and none is free. A split creates a new seam to design and a new part to own. A merge brings two teams, or two sets of habits, into one part. A retirement takes away something people may still believe is protecting them. And every re-cut changes the map that the people who run the process carry in their heads. So re-cutting is done deliberately, not continuously. A single flicker of a sign (one odd case crossing a seam, one week of extra traffic) is not drift; it is noise. Re-cut when the sign is clear and lasting: when the "and" has become permanent, when the seam has been thick for a while, when the leftover has been confirmed to serve nothing.

And re-cut so that what the parts around depend on holds. When a part is split, the parts around it should still be able to rely on the same result they relied on before; the split happens inside, and the outside barely notices. When two parts are merged, their combined result should be exactly what the two results made together. When a part is retired, whatever it was still quietly doing must be found and placed somewhere, or confirmed to be needed by no one. Done this way, a re-cut restores the design to sound without breaking what was working around it.

The highest possible standard is to answer drift with the response its sign calls for, splitting a part with two jobs at its natural joint, merging parts whose seam has thickened, and retiring parts whose result serves nothing, doing so deliberately when the signs are clear and lasting, and in a way that keeps the results the surrounding parts rely on intact.

Key Takeaway: Drift has three answers, each matched to a sign. Split a part with two jobs (an "and" in its name, two halves to its result), at the natural joint between them. Merge parts whose seam has thickened, because their constant talk means they belong on one side of the line. Retire a part whose result serves nothing, after confirming nothing still needs it. None is free: new seams, merged teams, a changed map in people's heads. So re-cut deliberately, when the sign is clear and lasting, not at every flicker. And re-cut so the results the surrounding parts rely on still hold.

Answer drift with the cut its sign calls for (split, merge or retire), deliberately and only when the signs are clear, keeping intact what the parts around rely on.

MarvinPro · PROCESS · Here is How to Build · Design · Sub · Discipline 7: Drift · Section: Split, merge, retire

MarvinPro | October 2026

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A real example

Return to activate and follow it through a few years of change. When it was designed, settling the payment handled card payments, and its cut was clean: one name, one result, a payment settled, or declined and the customer told. Then the company added digital wallets. They went inside settling, because that is where payments lived. Then bank transfers, which settle days later rather than in seconds. Then instalments, which settle a little at a time. Each addition was reasonable, and each landed in the nearest part. Nobody decided to blur settling. But now its name needs an "and" three times, its inside is four quite different flows, and the person fixing card retries has to load all four to change one.

The signs are clear and lasting, so settling is split inside itself. Not into arbitrary pieces, but at the natural joints, where the flows genuinely differ: card and wallet payments, which settle at once and fail the same way, stay together; bank transfers, with their days of waiting, become their own part within settling; instalments, settled over months, become another. And the split happens so the outside barely notices. Opening the account still relies on one result: a payment settled, or declined and the customer told. It does not need to know which of the payment parts inside settling produced it.

Two other signs have appeared in the same years. Recording the entitlement, once a single step, has grown with every change to the way plans are sold, and now it and opening the account talk constantly: every plan change touches both, details cross the seam back and forth, and neither can be changed without the other. The thick seam says they belong together, so they are merged into one part, with one result: an account open, with the entitlement recorded against it. And a manual fraud review, added during the launch of a new market and placed just before settling, is still running, still costing, still delaying a few customers each day, although the payment provider has since taken over that check entirely. Its result appears nowhere in the whole any more. Once it is confirmed that nothing else relies on it, it is retired. A split, a merge, a retirement: and activate, years on, is cut clean again for the work as it now is.

Settling had drifted into four jobs and was split inside itself at its natural joints; opening the account and recording the entitlement had drifted together and were merged; a fraud review had outlived its reason and was retired.

MarvinPro · PROCESS · Here is How to Build · Design · Sub · Discipline 7: Drift · A real example

MarvinPro | October 2026

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Drift

A clean design is sound on the day it is finished, but a process does not stand still. New work arrives, volumes shift, teams and systems change, and each change lands somewhere, usually not where it belongs but in whichever part is nearest. Each addition is reasonable; nobody decides to blur the parts. Yet over time a part grows a second job, neighbours start leaning on each other, and parts outlive their reason. That accumulated movement is drift, and it means a cut is right for the work as it was, not for all time.

Drift is slow, so it has to be read, not waited for, and the signs are the ones that confirmed the cut in the first place. A part's name needs an "and" again. Its result no longer fits in one line. A seam has thickened. Work keeps landing in the gap between two parts. A part's result appears nowhere in the whole. Check these regularly, and whenever a significant change lands, so drift is caught while it is small and cheap to correct.

And drift has three answers, each matched to its sign. Split a part with two jobs at the natural joint between them. Merge parts whose seam has thickened, because they belong on one side of the line. Retire a part whose result serves nothing, once it is confirmed that nothing still needs it. Each re-cut has a cost, so it is made deliberately, when the sign is clear and lasting, not at every flicker; and it is made so that the results the surrounding parts rely on still hold.

So the discipline is this: treat every cut as right for the work as it was, read drift from the signs that confirmed the cut, and answer it with a split, a merge or a retirement when the signs are clear. Done this way, the parts do not slowly blur into a process nobody can work on alone; they are kept cut clean for the work as it is now, change after change. That leaves one thing for the last discipline of this volume: to bring all of it together.

Expect the parts to drift; read the signs that confirmed the cut, and when they are clear, split, merge or retire, so the process stays cut clean for the work as it is now.

MarvinPro · PROCESS · Here is How to Build · Design · Sub · Discipline 7: Drift · Chapter Outcome

MarvinPro | October 2026

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