storage-engine-playground/tools/plan-viewer/README.md

## Query Plan Viewer

A static HTML viewer for `plan-runner` JSON files (the fixtures).
It evaluates a fixture in the browser and renders the plan DAG, the input facts, the relation computed at every plan node, and a per-row comparison against `expected_bindings`.

### Usage

Open [`index.html`](index.html) in a browser, then drop a fixture from `crates/plan-runner/fixtures/` onto the page or pick one with the file input.

When the repository is served over HTTP (`make viewer`), a fixture can also be loaded through a query parameter:

```text
http://localhost:8000/tools/plan-viewer/index.html?fixture=../../crates/plan-runner/fixtures/two_atom_join.json
```

### Scope

The viewer re-implements the operator semantics of `crates/query-ops` and `crates/plan-runner` in JavaScript, for display only.
The Rust crates and their tests remain the correctness oracle; if the two ever disagree, the Rust behavior wins and the viewer has a bug.
Only `scan` and `join` actions are supported.