Kanban
Scan-based pull replenishment. A kanban card ties an item to a bin, and a signal fires a purchase order, a job, or a stock transfer.
A is a physical pull signal represented by a printed card, QR code, or URL. It links an item, location, storage unit, and reorder quantity. Scanning the signal creates the purchase order, job, or stock transfer needed to refill the bin.
A reordering policy calculates suggestions from on-hand quantity, demand, and reorder points. Kanban replenishment is direct: a signal creates a real document immediately. Use policies for planning-driven replenishment and kanban for shop-floor pull.
What a kanban holds
Each kanban is a small record: an item, where it lives, how much to reorder, and how to reorder it. For a Transfer kanban, the form shows Item, Replenishment System, Location, From Storage Unit, To Storage Unit, Quantity, and Replenishment Level, in that order.
Transfer kanban, this is the quantity moved from the From storage unit.Buy (raise a purchase order), Make (create a job), or Transfer (create a stock transfer between two storage units in the location). See .Buy and Make.)Transfer only.)Transfer only.)Transfer only.)Buy kanbans.Buy only.)Make scan, release the created job to the floor when it passes the release checks, instead of leaving it in draft. (Make only.)Make scan, drop the operator straight into the first operation in MES. Requires Auto Release, and applies only when the job was released. (Make only.)Make only.)The scan flow
Each kanban has scan targets for order, start, and complete. A scan opens a URL, runs the action, and redirects to the resulting document. QR codes are black for order, emerald for start, and blue for complete.
The order scan (the create signal) branches on the replenishment system:
Draft or Planned) purchase order for that supplier and adds a line for the kanban's quantity. If none exists, it creates a new draft PO. It applies the kanban's conversion factor, purchase unit, and storage unit to the line, then drops you on the purchase order.Auto Release can leave the job in Draft
The scan runs the same checks as the job's Release dialog. When one fails, for example a material with no storage unit under strict backflush, the job stays Draft and linked to the card. The scan opens the job page with the reason, so you can fix it and release the job from there. The same happens when the item's method could not be copied onto the job.
Outside operations go on the supplier's newest Draft purchase order, or a new one. Nobody at the card can choose an order, so an existing draft does not stop the release.
Start and complete scans only apply to Make kanbans. They resolve the linked job's active operation and hand off to the MES operation start / complete screens, so an operator can drive the whole build from the same card that created the job.
A Make kanban links to the job it created (jobId). If you scan order again while that job is still open, Carbon doesn't create a duplicate. It routes you to a collision screen that shows the existing job and offers to remove the link so a fresh scan can start over. Once the job is completed or cancelled, the link clears automatically and the card is free to fire again.
Replenishment level
A Transfer kanban with a replenishment level refills its To storage unit without a scan. The projected quantity is the on-hand quantity at the To storage unit plus the outstanding quantity of every stock transfer into it that is not Completed. When the projected quantity is strictly below the level, Carbon creates one Released stock transfer for the fewest whole multiples of the kanban's Quantity that reach the level. With a level of 20, a Quantity of 5 and an empty storage unit, one transfer moves 20.
Three events start the check: a stock movement at the To storage unit, a save of the kanban, and an hourly sweep. Each transfer has a "Kanban replenishment" note and shows Kanban in the Source column. The database sends the signals through the Vault secret inngest_event_url, so without it a level never fires (environment variables).
Output format
How a card is rendered is a per-company setting, Kanban Output, with three modes:
| Mode | What a card is |
|---|---|
| QR code | A scannable QR code (the default), color-coded per action. |
| Label | A printed PDF label, six to a page, with the QR, item thumbnail, name, storage unit, quantity, and supplier. When the kanban has a replenishment level, a MIN: line prints under QTY:. |
| URL | A copyable link that hits the same scan endpoint directly. |
For Make kanbans, the list view also surfaces the start and complete affordances. Buy and Transfer kanbans show only the order signal, since there's no job to start. Two columns are hidden by default: Replenishment Level and Projected (To). Turn them on from the column picker. Projected (To) shows a Below level pill when the projected quantity is under the level.
Kanban vs. reordering policy
Both replenish stock, but they're different tools:
A kanban is a signal, not a plan
A reordering policy is evaluated by the planning engine, which computes suggested orders from on-hand, demand, and reorder points. A kanban skips all of that: a scan creates a real purchase order, job, or stock transfer on the spot. A replenishment level applies only to a Transfer kanban, and it creates a stock transfer. Reach for a kanban when the shop floor pulls material by hand and you want the refill to be one scan away.