Scope checks per package in a monorepo

Most of Straitjacket's rules look at one file at a time, so a monorepo is no different to them than a single package. Three rules are cross-file — they compare a file against the rest of the tree — and those need a boundary in a monorepo:

• duplication — otherwise it flags a clone between two independent packages as an error, even though the whole point of the boundary is that they don't share a helper.
• prop-drilling and store-passthrough — otherwise a component named the same in two packages (Button, Card) is conflated, and a forwarding chain can appear to cross a package it never imports.

Declare a project

Drop a .straitjacket.toml file in a package's root directory. Its presence marks that directory as a project: the cross-file rules partition on it and never compare files across the boundary.

packages/web/.straitjacket.toml
packages/admin/.straitjacket.toml

The file can be empty. A name is optional:

# packages/web/.straitjacket.toml
name = "web"

That's it. Run Straitjacket from the repo root as usual — a duplication clone or a forwarding chain is now only ever reported within one package.

straitjacket

How files map to projects

A file belongs to the nearest ancestor directory that holds a .straitjacket.toml. Files above every marker belong to the root project (the rest of the repo), and they still compare against each other. Nested markers work: an inner package carves its own subtree out of the outer one.

A repo with no markers is a single project — the whole scan — so nothing changes until you add the first boundary.

What still fires

Boundaries only stop comparisons across packages. A clone that lives wholly inside one package still fails, and every per-file rule (file-size, slop-prose, deep-nesting, one-component, color, emoji, …) is unchanged. The suppression markers still work for the one-off exceptions a boundary shouldn't cover.