Guide

Keeping what you learn

The costly part of working in a large codebase is rarely writing the code. It is the hours spent discovering why something is the way it is — and the fact that the discovery evaporates when the session ends. capture_concept is where it goes instead.

1 · Notice the moment

The signal is a specific feeling: I wish I had known that three hours ago. A platform behaving unlike its documentation, a constraint with no visible cause, a fix that looks arbitrary until you know what it prevents. Capture it before moving on — you will not come back.

2 · Reduce it to one sentence

The invariant is the whole thing. If it needs “and” to be stated, it is two concepts and should be captured as two. Everything else — the mechanism, the stakes, the case that makes it click — goes in the fields underneath, where it does not dilute the claim.

3 · Say where it applies

Relevance is a set of URI globs, and it is what makes a concept useful rather than merely stored: anyone who opens a matching file is handed it, without having to know it exists or go looking.

capture_concept( name="CloudRunCpuIsPerRequest", category="rule", invariant="Background work after the response crawls on Cloud Run.", why="CPU is allocated per request, so a task started after the" "response returns runs at a fraction of a core.", relevance="file:///src/cloud/**", isUniversal=false)

4 · Give it evidence, if it can have any

A claim about code should point at the code that proves it. Anchor the verification at the symbol rather than the line — #symbol=Name keeps resolving as the file moves under it — and set a ttlDays for how long that evidence stays trusted before it is checked again.

5 · Read what is already there

Before solving something that feels hard, ask whether it has been solved. Concepts answer to the same addresses as everything else.

read("file:///src/cloud/** => concepts") read("concept:///rule/cloud/** => structure")

Written this way, the lesson stops being something a person remembers and starts being something the repository knows.

This page names what exists. The depth behind every name — the bounds, the failure modes, how they compose — ships inside the binary at help:///, and answers to explore and read exactly like your code does. Install it, and your agent has the manual.