The changelog is the asset, not the output
An agent's value compounds only when what it did is recorded in a form a later causal read can actually use. The changelog outlives both the agent and the vendor.
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By Joris van Huët, Founder & CEOUpdated 2 min read
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The listings are replaceable. The record of what changed and when is not. That record is what any later measurement depends on.
Why the record is the durable part
A batch of rewritten listings is worth whatever it earns this quarter. The log of which products changed, when, and what was left alone is what lets you answer the same question next quarter and the one after.
Swap the agent, swap the vendor, swap the platform: the log still works, because it describes your catalogue rather than their tooling.
What a usable log contains
| Field | Used for |
|---|---|
| Batch timestamp, to the hour | Before and after boundary |
| Product ids changed | Defining the treated set |
| Product ids deliberately excluded | Defining the control |
| Field-level description of the change | Knowing which lever moved |
| External events in the window | Ruling out confounds |
Field-level matters. "Updated listings" is not a lever. "Rewrote the first paragraph of the description, left titles and images alone" is.
Where teams lose it
The log lives in the agent's transcript, the transcript lives in a session, and the session is gone in a month. Or it lives in a chat thread nobody exports. Either way the information existed and was not kept.
Write it to something you own, at the moment of the change. A row in your own database beats a perfect account that has been deleted.
The connection to ROAS
Without the log, every later read is a before-and-after across a period where an unknown set of things changed, which is the weakest design there is.
Related answers
Frequently asked questions
Why is the changelog more valuable than the changes?
The listings earn what they earn this quarter. The record of what changed, when, and what was left alone is what lets you answer the same question in later quarters, and it survives changing agent, vendor or platform.What level of detail does a changelog need?
Field level. Updated listings is not a lever. Rewrote the first paragraph of the description and left titles and images alone is, because it names which thing could have caused the effect.Where should the changelog live?
Somewhere you own, written at the moment of the change. Agent transcripts and chat threads disappear, and a perfect record that has been deleted is worth less than a rough row in your own database.
Go deeper: Causal attribution, explained.
Sixty-second versions of these ideas: Causality Engine on YouTube Shorts.
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Terms in this article
- AttributionAttribution identifies user actions that contribute to a desired outcome and assigns value to each. It reveals which marketing touchpoints drive conversions.
- IncrementalityIncrementality is the part of an outcome, such as orders or revenue, that a marketing activity caused: the extra results compared with what would have happened without it. It is a causal effect, not the number of conversions credited to a channel.
- ROASROAS: Return on Ad Spend measures the revenue generated for each dollar spent on advertising. Causal attribution calculates an accurate ROAS by showing the true impact of ad campaigns.
- SessionA Session is a group of user interactions with your website within a given timeframe. It can include multiple page views, events, and transactions.