Your editor shows every line the same.
doloop shows you where to look.

Doesn't Cursor or VS Code already do this?

The honest answer is no, and it is worth being precise about why, because the three things that look like this are each doing something else.

1. Syntax highlighting, the minimap, the outline. This is the novice's panel. It colors by universal category: every function the same in every file, every comment greyed by one rule, every symbol in the outline at equal weight. Everything lit by a fixed rule means nothing is ranked. It cannot tell you which file matters in this codebase, because it does not read this codebase. It reads the language.
2. CodeLens reference counts. The closest thing any editor ships, and it points the wrong way. "N references" is raw fan-in, the most-imported file, which is the connective tissue. That is the file you should read last, not first. The one place the IDE tries to surface importance, it surfaces the plumbing.
3. "Explain this repo" from an AI assistant. The real overlap, and we will not wave it away. An assistant reading your code is a comprehension tool. But it tells, in a wall of prose, instead of showing a ranked map. It is different every time you ask. It costs tokens. And on a large repo it reads a slice through the context window, not the whole.

The empty quadrant

IDEs render the novice's gaze: universal rules, equal weight, you crawl it yourself. AI assistants render a prose summary: stochastic, token-costly, bound to a keyhole. The deterministic, whole-repo, codebase-relative expert's gaze, greying the connective tissue, lighting the code that carries the work, naming the doors in this repo, is in neither box.

What it paints

• dims the line ranges that are connective tissue, so your eye skips them
• lights the units that carry the decisions, the muscle of the file
• a gutter mark on the doors, the files an expert opens first
• a ranked "where to look" list in the sidebar
• a band on the overview ruler beside the scrollbar, this repo's red line through the file

All deterministic, all local, zero tokens. It rides VS Code's and Cursor's own decoration surface, so there is nothing new to learn and nothing leaves your machine.

Where the line is

doloop decorations is complementary, not a replacement. It will not answer your specific question or explain the semantics in prose. That is the assistant's job, and the read view hands off to it: read the map here, ask for the story there. What doloop does that nothing else is set up to do is play a deterministic, whole-codebase, show-don't-tell game. We are not claiming to have settled how a person comes to understand a codebase. We are the only ones standing in the place where that question gets a reproducible answer.

It runs unmodified in VS Code and Cursor (same extension API). Bring nothing but the editor you already use.