Most commerce platforms are pipelines. They take a product from the seller, push it down a one-way pipe to the buyer, and the platform's job is done. Resale, repair, return, renewal — those happen after the platform stops paying attention.
That worked when consumer goods were cheap and the planet was unmetered. It does not work anymore, and a generation of commerce founders has spent the last five years bolting circular flows onto pipeline platforms with varying degrees of success.
Why retrofits fail
The retrofit pattern looks like this: take a pipeline platform, add a "returns" module, add a "refurbishment" workflow, add a "resale" listing type, add a "warranty" tracker. Each one bolts onto the catalog with foreign keys and tries to coordinate with the rest via webhooks.
The result: every circular flow has its own data model, its own ledger entries (or worse, its own off-ledger accounting), and its own integration with the warehouse. By the time you have take-back, repair, resale and return-to-vendor running, you have four semi-independent systems that all need to agree on the same physical inventory.
You can tell circular commerce was retrofitted because the physical inventory is in one column and the state of that inventory is in a JSON blob.
What "first-class" means
In VenduStack, every flow that moves an item between parties is the same kind of object — a Move (see our post on the data model). That includes:
- Initial sale (seller → buyer)
- Return (buyer → seller, reversing entries)
- Take-back (former buyer → platform, valued at trade-in price)
- Refurbishment (platform → repair partner, with a grade update on the Thing)
- Resale (platform → new buyer, at a new grade and a new price)
- Return-to-vendor (platform → original seller, with reverse logistics fees)
Each one is a Move with a state machine, ledger entries and an audit trail. There is no separate "returns module" — there is the workflow library, and "return" is one of the workflows that ships with it.
What this unlocks
Once circular flows are first-class, things that used to be hard become easy:
- Buy-back from day one. The take-back price is part of the product's own model, not a separate program.
- Grade-aware inventory. One physical Thing can be in different grades over its lifetime; the ledger tracks the value at each grade.
- Royalties on resale. If you want the original seller to earn on secondary sales, that is a payout policy on the Thing.
- Honest carbon accounting. Every move has a kind and a counterparty; emissions and impact can be attributed deterministically.
The boring detail
What makes this work is not the model itself but the fact that the model was decided before the catalog had grown to a million SKUs. Retrofits fail because they have to keep the old shape intact. First-class circular only works if you commit to it on day one.
That is the practical reason to pick a platform that ships it as a default, not as a module: by the time you need it, retrofitting it onto your existing stack is going to be a year of work.
What we are still figuring out
Circular flows interact with tax, with depreciation, with insurance and with regulator reporting in ways that vary by jurisdiction. We have the data model right; we are working with three design partners on the regulatory shape across EU, UK and North America.
If your commerce operation depends on getting circular flows right — or if you have tried to retrofit them and learned what we did — we would love to compare notes.
S. Lange is Head of Product at VenduSys. Previously: product at a refurbished-electronics marketplace and a circular-fashion platform. Based in Amsterdam.