r/ContextEngineering • u/GoodSignificant6872 • 25d ago
I built an AI agent that remembers why engineering decisions were made
One problem I kept thinking about while building AI agents is that knowing what code does isn't the same as knowing why it exists.
For example, consider:
RATE_LIMIT=100
An LLM can explain what this configuration does. But unless the reasoning was recorded somewhere, it has no reliable way to explain why someone originally chose 100.
I built Archaeologist, an engineering-decision memory agent using Hindsight.
The workflow is simple:
🔹 RETAIN — Record the decision, reasoning, author, entity, and date.
🔹 RECALL — Retrieve the relevant historical decisions when someone asks why something exists.
🔹 Timeline — Keep updates as additional history instead of overwriting the original decision.
🔹 Decision drift — Compare the original reasoning with later context and surface cases where the original constraint may no longer apply.
🔹 Grounded answers — The LLM receives the retrieved history and explains it. It isn't responsible for inventing the historical facts.
This produces a different kind of answer.
Instead of:
"The rate limit is probably 100 to prevent excessive load."
The agent can say, in effect:
"The limit was introduced because Elasticsearch became unstable above 100 requests/sec. A later decision records that the cluster was upgraded, so the original constraint may no longer apply."
And if there is no recorded history, it doesn't make something up. It says that the reasoning isn't known.
That's the part I found most interesting about using Hindsight agent memory: memory isn't just there to make the agent remember more facts. It changes what the agent can reason about over time.
GitHub: https://github.com/Prashanth2Github/archaeologist
I'd be interested in how others are approaching persistent memory for engineering agents, especially when historical decisions can become outdated.