Why your prototype records should be append-only
Editable records lose the thing you need most when debugging hardware: what changed and when. How append-only history works and why it matters for traceability.
Published
Most tools that store engineering data are mutable: when you change a value, the old one is gone. For prototypes that’s a problem, because the most useful information about a board is often what it used to be.
The question behind every debugging session
When a prototype that used to work stops working, the first question is always “what changed?”. Maybe it went to the environmental chamber. Maybe it was reworked to the new regulator. Maybe someone moved it to a different test rig. If your records only hold the current state, all you know is where the board is now.
What “append-only” means
An append-only record never overwrites or deletes history. Every change creates a new entry that says:
- What changed (the field, with its old and new values),
- Who changed it,
- When it happened.
The current state is still easy to see, but the full sequence of states that led there is preserved.
Three properties that make history trustworthy
Plenty of tools have a history feature. Fewer have one you can rely on in a failure investigation or an audit. Look for these properties:
1. It’s automatic
If people have to remember to write a log entry, there will be gaps. History should be a side effect of making the change.
2. It’s atomic
The change and its history entry should be committed together, so it’s impossible for one to exist without the other. Proto Tracker writes both in a single DynamoDB transaction. If the history can’t be written, the change doesn’t happen.
3. It’s immutable
If history can be edited, it’s a draft. Proto Tracker has no mechanism in the application to edit or delete history entries, and deleted prototypes keep their full record, so you can still see what happened to a board after it’s been scrapped.
Labels, not just IDs
A subtle failure mode: history that records “location changed from 7f3a… to 91bc…” becomes unreadable once locations are renamed or deleted. Good history stores the human-readable label at the time of the change (“Lab → EMC test house”) as well as the ID.
Traceability and audits
Quality systems such as ISO 9001 expect organisations to control and retain documented information, including evidence of changes. An append-only, exportable history of your prototypes won’t make you compliant on its own, but it turns “can you show us how this unit changed?” from an afternoon of reconstruction into a CSV export.
Try it
Every Proto Tracker plan, including the free one, includes the full append-only history, per-prototype timelines and CSV/JSON export. See the features or read how we keep that data secure.